JP7500318B2 - Anodizing Equipment - Google Patents

Description

An embodiment of the present invention relates to an anodizing apparatus.

A technology is known that uses anodization to form a porous layer on the silicon surface.

JP 2004-111491 A

We provide an anodizing device that can form multiple porous layers with different film properties on the surface of a substrate.

The anodizing apparatus according to the embodiment includes a cylindrical first treatment tank capable of anodizing a substrate, a cylindrical second treatment tank capable of anodizing a substrate, a second treatment tank having an inner diameter smaller than that of the first treatment tank, and arranged concentrically inside the first treatment tank, a first electrolytic solution supply unit capable of supplying a first electrolytic solution to the first treatment tank, a second electrolytic solution supply unit capable of supplying a second electrolytic solution to the second treatment tank , a first electrode provided above at least the first treatment tank , a second electrode provided below the first treatment tank and the second treatment tank and in contact with lower ends of the first treatment tank and the second treatment tank , and a holding section capable of holding a substrate between the first electrode and the first treatment tank and the second treatment tank such that a first surface of the substrate faces the first electrode, a second surface opposing the first surface of the substrate faces the second electrode, and the second surface is in contact with the first electrolytic solution supplied to the first treatment tank and the second electrolytic solution supplied to the second treatment tank .

FIG. 1 is a block diagram of an anodizing apparatus according to the first embodiment. FIG. 2 is a perspective view of an anodizing unit included in the anodizing apparatus according to the first embodiment. FIG. 3 is a cross-sectional view of an anodizing unit included in the anodizing apparatus according to the first embodiment. FIG. 4 is a graph showing the results of monitoring the concentration of the electrolyte during anodizing in the anodizing apparatus according to the first embodiment. FIG. 5 is a diagram showing a semiconductor substrate that has been anodized using the anodizing apparatus according to the first embodiment. FIG. 6 is a diagram showing a method for manufacturing a semiconductor device using a semiconductor substrate that has been anodized using the anodizing apparatus according to the first embodiment. FIG. 7 is a perspective view of an anodizing unit included in an anodizing apparatus according to a first example of the second embodiment. FIG. 8 is a cross-sectional view of an anodizing unit included in an anodizing apparatus according to a first example of the second embodiment. FIG. 9 is a block diagram of an anodizing apparatus according to a second example of the second embodiment. FIG. 10 is a perspective view of an anodizing unit included in an anodizing apparatus according to a second example of the second embodiment. FIG. 11 is a cross-sectional view of an anodizing unit included in an anodizing apparatus according to a second example of the second embodiment. FIG. 12 is a perspective view of an anodizing unit included in an anodizing apparatus according to a third example of the second embodiment. FIG. 13 is a cross-sectional view of an anodizing unit included in an anodizing apparatus according to a third example of the second embodiment. FIG. 14 is a flowchart of anodizing in the anodizing apparatus according to the first example of the third embodiment. FIG. 15 is a flowchart of anodizing in an anodizing apparatus according to a second example of the third embodiment. FIG. 16 is a flowchart of anodizing in an anodizing apparatus according to a third example of the third embodiment. FIG. 17 is a flowchart of anodizing in an anodizing apparatus according to a fourth example of the third embodiment. FIG. 18 is a flowchart of anodizing in an anodizing apparatus according to a fifth example of the third embodiment. FIG. 19 is a flowchart of anodizing in an anodizing apparatus according to a sixth example of the third embodiment. FIG. 20 is a block diagram of an anodizing apparatus according to a first example of the fourth embodiment. FIG. 21 is a block diagram of an anodizing apparatus according to a second example of the fourth embodiment. FIG. 22 is a block diagram of an anodizing apparatus according to a third example of the fourth embodiment. FIG. 23 is a block diagram of an anodizing apparatus according to a fourth example of the fourth embodiment. FIG. 24 is a block diagram of an anodizing apparatus according to a first example of the fifth embodiment. FIG. 25 is a cross-sectional view of an anodizing processor included in an anodizing apparatus according to a first example of the fifth embodiment. FIG. 26 is a top view of a holding portion and a fixing portion of an anode correction processing portion provided in an anodizing apparatus according to a first example of the fifth embodiment. FIG. 27 is a cross-sectional view of an anodizing processor included in an anodizing apparatus according to a second example of the fifth embodiment. FIG. 28 is a block diagram of an anodizing apparatus according to a third example of the fifth embodiment. FIG. 29 is a cross-sectional view of an anodizing processor included in an anodizing apparatus according to a third example of the fifth embodiment. FIG. 30 is a cross-sectional view of an anodizing processor included in an anodizing apparatus according to a fourth example of the fifth embodiment. FIG. 31 is a block diagram of an anodizing apparatus according to the sixth embodiment. FIG. 32 is a block diagram of an anodizing apparatus according to a first example of the seventh embodiment. FIG. 33 is a cross-sectional view of an anodizing processor included in an anodizing apparatus according to a first example of the seventh embodiment. FIG. 34 is a cross-sectional view of an anodizing processor included in an anodizing apparatus according to a second example of the seventh embodiment. FIG. 35 is a block diagram of an anodizing apparatus according to a third example of the seventh embodiment. FIG. 36 is a cross-sectional view of an anodizing processor included in an anodizing apparatus according to a third example of the seventh embodiment. FIG. 37 is a cross-sectional view of an anodizing processor included in an anodizing apparatus according to a fourth example of the seventh embodiment. FIG. 38 is a block diagram of an anodizing apparatus according to a first example of the eighth embodiment. FIG. 39 is a block diagram of an anodizing apparatus according to a second example of the eighth embodiment. FIG. 40 is a block diagram of an anodizing apparatus according to a third example of the eighth embodiment. FIG. 41 is a block diagram of an anodizing apparatus according to a fourth example of the eighth embodiment. FIG. 42 is a cross-sectional view of an anodizing processor included in an anodizing apparatus according to a first example of the ninth embodiment. FIG. 43 is a top view of a holding portion and a fixing portion of an anode correction processing portion provided in an anodizing apparatus according to a first example of the ninth embodiment. FIG. 44 is an enlarged view of the region RA in FIG. FIG. 45 is an enlarged view of region RA in FIG. FIG. 46 is a cross-sectional view of a holding portion and a fixing portion of an anode repair processing portion provided in an anodizing apparatus according to a second example of the ninth embodiment.

The embodiments are described below with reference to the drawings. In the following description, components having substantially the same functions and configurations are given the same reference numerals, and repeated explanations are given only when necessary. Furthermore, each embodiment shown below is an example of an apparatus or method for embodying the technical idea of the embodiment, and the technical idea of the embodiment does not specify the material, shape, structure, arrangement, etc. of the components as described below. The technical idea of the embodiment may be modified in various ways within the scope of the claims.

1. First Embodiment An anodizing apparatus according to a first embodiment will be described.

1.1 Overall Configuration First, an example of the overall configuration of an anodizing apparatus will be described with reference to Fig. 1. Fig. 1 is a block diagram of the anodizing apparatus.

As shown in FIG. 1, the anodizing device 1 includes an anodizing processing section 10, an electrolyte A supply unit 11, an electrolyte B supply unit 12, a current supply unit 13, and a control circuit 14.

The anodizing unit 10 includes a treatment tank and electrodes (anode and cathode) corresponding to the treatment tank, and performs anodizing on the surface of the semiconductor substrate. The configuration of the anodizing unit 10 will be described later.

The electrolyte A supply unit 11 supplies electrolyte A to a treatment tank provided in the anodizing treatment unit 10. The electrolyte A supply unit 11 has a mechanism (e.g., a pump, etc.) not shown for adjusting the liquid pressure of the electrolyte A supplied to the treatment tank. The electrolyte A is a treatment liquid used in the anodizing treatment. For example, a liquid containing hydrofluoric acid (HF) is used as the electrolyte A. The electrolyte A supply unit 11 of this embodiment does not have a function for circulating the liquid (electrolyte A) between the anodizing treatment unit 10 and the electrolyte A mixing tank 20. That is, the electrolyte A supply unit 11 supplies unused (new) electrolyte A to the anodizing treatment unit 10.

The electrolyte A supply unit 11 includes an electrolyte A mixing tank 20, a supply control unit 21, a plurality of liquid supply units 22 (three liquid supply units 22a to 22c in the example of FIG. 1), and a concentration sensor 23.

The electrolyte A mixing tank 20 is a tank for mixing multiple liquids to produce electrolyte A. The electrolyte A supply unit 11 produces electrolyte A by mixing, for example, three liquids A to C as raw materials. The three liquids A to C may be, for example, an HF solution, DIW (deionized water), and alcohol. The liquids used to produce electrolyte A are not limited to three types. Materials other than liquids may also be used to produce electrolyte A. The produced electrolyte A is supplied to the treatment tank in the anodizing treatment unit 10 through the pipe 17.

The supply control unit 21 controls the supply amounts of liquids A to C supplied to the electrolyte A mixing tank 20 under the control of the control circuit 14. For example, the supply control unit 21 includes valves and flow meters provided in the supply lines of each liquid.

The liquid supply units 22a to 22c are each connected to the electrolyte A mixing tank 20 by a supply line (piping). The liquid supply units 22a to 22c supply the electrolyte A mixing tank 20 with the liquids A to C, respectively, via the supply line. The liquid supply units 22a to 22c may each have a mechanism for pumping the liquids A to C from the containers of the liquids A to C, for example.

The concentration sensor 23 monitors the concentration of electrolyte A (e.g., F concentration) in the electrolyte A mixing tank 20 and transmits the result to the control circuit 14. The control circuit 14 controls the supply control unit 21 based on the result of the concentration monitoring to adjust the concentration of electrolyte A.

The electrolyte B supply unit 12 supplies electrolyte B to a treatment tank different from the treatment tank to which electrolyte A is supplied, which is provided in the anodizing treatment unit 10. The electrolyte B supply unit 12 has a mechanism (e.g., a pump, etc.) not shown for adjusting the liquid pressure of the electrolyte B supplied to the treatment tank. The electrolyte B is a treatment liquid used in the anodizing treatment. The electrolyte B may be the same as the electrolyte A, or may be different. In the following, the electrolyte B has a different concentration (F concentration) from the electrolyte A. A liquid containing HF is used for the electrolyte B. The electrolyte B supply unit 12 of this embodiment has a function for circulating the electrolyte B between the anodizing treatment unit 10 and the electrolyte B mixing tank 30. That is, the electrolyte B supply unit 12 adjusts the components of the liquid recovered from the anodizing treatment unit 10 and can supply it again to the anodizing treatment unit 10.

The electrolyte B supply unit 12 includes an electrolyte B mixing tank 30, a supply control unit 31, a plurality of liquid supply units 32 (three liquid supply units 32a to 32c in the example of FIG. 1), and a concentration sensor 33.

The electrolyte B mixing tank 30 is a tank for mixing multiple liquids to generate electrolyte B. The electrolyte B supply unit 12 can generate electrolyte B and adjust its concentration by mixing the liquid recovered from the anodizing treatment unit 10 via the pipe 16 as a raw material with three liquids D to F. The three liquids D to F may be, for example, an HF solution, DIW, and alcohol. The liquids used to generate electrolyte B are not limited to three types. Materials other than liquids may also be used to generate electrolyte B. The generated electrolyte B is supplied to one of the treatment tanks of the anodizing treatment unit 10 through the pipe 15. The electrolyte B mixing tank 30 also has an overflow pipe for draining the liquid in the tank when the liquid in the tank overflows.

The supply control unit 31 controls the supply amounts of liquids D to F supplied to the electrolyte B mixing tank 30 under the control of the control circuit 14. For example, the supply control unit 31 includes valves and flow meters provided in the supply lines of each liquid.

The liquid supply units 32a to 32c are each connected to the electrolyte B mixing tank 30 by a supply line. The liquid supply units 32a to 32c supply liquids D to F to the electrolyte B mixing tank 30 via the supply line. The liquid supply units 32a to 32c may each have a mechanism for pumping liquids D to F from the containers of liquids D to F, for example.

The concentration sensor 33 monitors the concentration of electrolyte B (e.g., F concentration) in the electrolyte B mixing tank 30 and transmits the result to the control circuit 14. The control circuit 14 controls the supply control unit 31 based on the result of the concentration monitoring to adjust the concentration of electrolyte B.

The current supply unit 13 supplies current to the electrodes provided within the anodizing treatment unit 10 under the control of the control circuit 14.

The control circuit 14 controls the entire anodizing device 1.

1.2 Detailed configuration of the anodizing unit Next, an example of the detailed configuration of the anodizing unit 10 will be described with reference to Figs. 2 and 3. Fig. 2 is a perspective view of the anodizing unit 10. Fig. 3 is a cross-sectional view of the anodizing unit 10 in a state in which electrolytic solutions A and B are being supplied. The examples of Figs. 2 and 3 show a case in which the anodizing unit 10 includes two upper electrodes connected to different current sources, and two treatment tanks. Hereinafter, this configuration will also be referred to as "split electrodes, multiple power sources, split treatment tanks".

As shown in FIG. 2, the anodization treatment unit 10 includes treatment tanks 101 and 103, a bath 102, upper electrodes 104 and 106, an insulator 105, and a lower electrode 107. The insulator 105 may be omitted. In this case, for example, an air gap may be provided between the upper electrodes 104 and 106. In other words, it is sufficient that the upper electrodes 104 and 106 are not electrically connected.

The treatment tank 101 has, for example, a cylindrical shape. The inner diameter of the treatment tank 101 is, for example, approximately the same as the inner diameter of the semiconductor substrate 1000 to be anodized. In the following, a case where the semiconductor substrate 1000 is a single crystal silicon (Si) substrate will be described. The bottom surface of the treatment tank 101 contacts the lower electrode 107. During anodization, the upper end of the treatment tank 101 is located near the surface of the semiconductor substrate 1000. In other words, the upper end of the treatment tank 101 does not contact the lower surface (the surface to be anodized) of the semiconductor substrate 1000. The treatment tank 101 is made of, for example, an insulating material that is resistant to the electrolytes A and B. Pipes 15 and 18 are connected to the treatment tank 101. Pipe 15 is a liquid supply line to the treatment tank 101. Pipe 18 is a liquid discharge line from the treatment tank 101.

The vat 102 is provided to collect the liquid overflowing from the upper end of the treatment tank 101. The vat 102 has, for example, a cylindrical shape. The inner diameter of the vat 102 is larger than the outer diameter of the treatment tank 101, the upper electrode 104, and the semiconductor substrate 1000. The vat 102 is arranged, for example, concentrically with the treatment tank 101. The bottom surface of the vat 102 contacts, for example, the upper end of the treatment tank 101 or the outer periphery near the upper end. The height position of the upper end of the vat is higher than the upper end of the treatment tank 101. The vat 102 is made of, for example, an insulating material that is resistant to the electrolytes A and B. The vat 102 may be made of the same material as the treatment tank 101. A pipe 16 is connected to the vat 102. The pipe 16 is a liquid discharge line from the vat 102.

The treatment tank 103 has, for example, a cylindrical shape. The inner diameter of the treatment tank 103 is smaller than the inner diameter of the treatment tank 101. The bottom surface of the treatment tank 103 is in contact with the lower electrode 107, and the treatment tank 103 is arranged, for example, concentrically with the treatment tank 101. The height position of the upper end of the treatment tank 103 is approximately the same as that of the treatment tank 101. The upper end of the treatment tank 103 is not in contact with the lower surface of the semiconductor substrate 1000, as with the treatment tank 101. The treatment tank 103 is made of, for example, an insulating material that is resistant to the electrolytes A and B. The treatment tank 103 may be made of the same material as the treatment tank 101. Pipes 17 and 19 are connected to the treatment tank 103. Pipe 17 is a liquid supply line to the treatment tank 103. Pipe 19 is a liquid discharge line from the treatment tank 103.

The upper electrode 104 functions as an anode in the anodization process using the treatment tank 101. Therefore, the upper electrode 104 faces the treatment tank 101. The upper electrode 106 functions as an anode in the anodization process using the treatment tank 103. Therefore, the upper electrode 106 faces the treatment tank 103. Above the treatment tanks 101 and 103, the insulator 105 and the upper electrode 104 are provided concentrically with the upper electrode 106 at the center. That is, the upper electrodes 106 and 104 are provided concentrically, and the insulator 105 is provided between the upper electrodes 106 and 104. As a result, the upper electrodes 106 and 104 are not electrically connected.

The outer diameter of the upper electrode 106 is approximately the same as the outer diameter of the processing tank 103. The outer diameter of the upper electrode 104 is approximately the same as the outer diameter of the processing tank 101. In other words, the outer diameter of the upper electrode 104 is approximately the same as the semiconductor substrate 1000. In addition, the inner diameter of the upper electrode 104 is approximately the same as the outer diameter of the processing tank 103.

In this embodiment, different currents are supplied to the upper electrodes 104 and 106 from the current supply unit 13. More specifically, the current supply unit 13 includes current sources 40 and 41. The current source 40 is connected to the upper electrode 104 and the lower electrode 107, and supplies an arbitrary current to the upper electrode 104 during anodizing. The current source 41 is connected to the upper electrode 106 and the lower electrode 107, and supplies an arbitrary current to the upper electrode 106 during anodizing.

The lower electrode 107 faces the upper electrodes 104 and 106 and functions as a cathode in the anodization process. The upper electrodes 104 and 106 and the lower electrode 107 are made of a conductive material.

In addition, multiple pipes 15 to 19 may be provided for each of the treatment tanks 101 and 103 and the vat 102.

As shown in FIG. 3, the anodization processing unit 10 includes a holding unit 108. The semiconductor substrate 1000 is placed by the holding unit 108 so that its back surface contacts the bottom surfaces of the upper electrodes 104 and 106 and its front surface (the surface to be anodized) faces downward (toward the processing tanks 101 and 103). A gap GP1 is provided between the upper end of the processing tank 101 and the semiconductor substrate 1000. A gap GP2 is provided between the upper end of the processing tank 103 and the semiconductor substrate 1000.

In this embodiment, when electrolytes A and B are supplied simultaneously to the anodizing treatment unit 10, the liquid pressure of electrolyte A supplied to the treatment tank 103 is set higher than the liquid pressure of electrolyte B supplied to the treatment tank 101 (liquid pressure of electrolyte A > liquid pressure of electrolyte B). In addition, during anodizing treatment, the pipes 18 and 19 are closed. As a result, electrolyte A flows from the treatment tank 103 to the treatment tank 101 through the gap GP2. At this time, since the liquid pressure of electrolyte A is higher than the liquid pressure of electrolyte B, electrolyte B does not flow from the treatment tank 101 to the treatment tank 103. In addition, the excess electrolyte B in the treatment tank 101 (electrolyte B mixed with electrolyte A) flows into the vat 102 through the gap GP1.

3, the outer diameter of the processing tank 101 is smaller than the inner diameter of the semiconductor substrate 1000. For this reason, a gap GP1 is provided between the upper end of the processing tank 101 and the semiconductor substrate 1000, but this is not limited thereto. For example, the inner diameter of the processing tank 101 may be larger than the outer diameter of the semiconductor substrate 1000 including the holding portion 108, and the upper end of the processing tank may be located higher than the surface (lower surface) of the semiconductor substrate 1000 to be anodized. In this case, a gap GP1 is provided between the inside of the upper end of the processing tank 101 and the holding portion 108 (and the outer diameter of the semiconductor substrate 1000).

1.3 Example of Adjustment of Concentration of Electrolyte Next, an example of adjustment of the concentration of the electrolyte will be described with reference to Fig. 4. Fig. 4 is a graph showing the monitoring results of the concentration sensor 33 in the electrolyte B supply unit 12.

As shown in FIG. 4, first, at time t0, the electrolyte B supply unit 12 generates electrolyte B having a preset adjustment target concentration in the electrolyte B mixing tank 30. Then, the electrolyte B supply unit 12 supplies the generated electrolyte B to the treatment tank 101.

At time t1, anodization begins. The anodization is carried out during the period from time t0 to t6. During this period, electrolyte B is circulated between the treatment tank 101 and the electrolyte B mixing tank 30.

During the period from time t1 to t2, the concentration of electrolyte B gradually decreases due to the anodization process.

At time t2, when the concentration of electrolyte B falls to a preset lower limit concentration at which anodization can be performed, the electrolyte B supply unit 12 adds at least one of liquids D to F to the electrolyte B mixing tank 30 to start adjusting the concentration of electrolyte B.

During the period from time t2 to t3, the electrolyte B supply unit 12 adjusts the concentration of electrolyte B.

At time t3, when the concentration of electrolyte B reaches the adjustment target concentration, the electrolyte B supply unit 12 ends the adjustment of the concentration of electrolyte B.

During the period from time t3 to t4, the concentration of electrolyte B gradually decreases due to the anodization process.

At time t4, when the concentration of electrolyte B falls to a preset lower limit concentration at which anodization can be performed, the electrolyte B supply unit 12 starts adjusting the concentration of electrolyte B again.

During the period from time t4 to t5, the electrolyte B supply unit 12 adjusts the concentration of electrolyte B.

At time t5, when the concentration of electrolyte B reaches the adjustment target concentration, the electrolyte B supply unit 12 ends the adjustment of the concentration of electrolyte B.

At time t6, the anodization process is completed. Note that, in the example of FIG. 4, after the anodization process is completed at time t6, the electrolyte B supply unit 12 adjusts the concentration of the electrolyte B again in preparation for the next process, but this is not limited to the above. The electrolyte B may be discharged.

1.4 Surface State of Semiconductor Substrate After Anodizing Treatment Next, the surface state of the semiconductor substrate 1000 after anodizing treatment will be described with reference to Fig. 5. The example of Fig. 5 is a diagram showing the surface and cross section of the semiconductor substrate 1000 after anodizing treatment.

As shown in FIG. 5, by using the anodizing apparatus 1 of this embodiment, a porous layer (e.g., a porous Si layer) having different characteristics is formed concentrically on the surface of the semiconductor substrate 1000 (the surface to be anodized).

More specifically, a porous layer 1100 corresponding to the upper electrode 106 and the treatment tank 103 (electrolyte A) is formed in the center of the surface of the semiconductor substrate 1000. A porous layer 1200 corresponding to the upper electrode 104 and the treatment tank 101 (electrolyte B) is formed in the outer periphery of the surface of the semiconductor substrate 1000. The porous layers 1100 and 1200 have different anodization conditions. Specifically, the anodization conditions are, for example, the amount of current (the amount of current per unit area of the upper electrodes 104 and 106) supplied to the upper electrodes 104 and 106, and/or the concentrations of the electrolytes A and B. As a result, the anodization device 1 can form the porous layers 1100 and 1200 with different film qualities (mechanical strength). The porous layers 1100 and 1200 differ in, for example, hardness, average particle size of the porous particles, density, or layer thickness. For example, the hardness of the porous layer 1100 may be higher or lower than that of the porous layer 1200. For example, the hardness can be measured by a Vickers hardness tester. The average particle size can be measured by a gas adsorption method.

1.5 Specific Example of a Method for Manufacturing a Semiconductor Device Using a Semiconductor Substrate that has been Anodized Next, a specific example of a method for manufacturing a semiconductor device using a semiconductor substrate 1000 that has been anodized will be described with reference to FIG. 6. FIG. 6 is a flow chart showing an example of a method for bonding semiconductor substrates. As one method for manufacturing a semiconductor device, there is a method for forming a semiconductor device by bonding a first (semiconductor) substrate on which a device layer 1 is formed and a second (semiconductor) substrate on which a device layer 2 is formed. The device layers 1 and 2 are provided with various circuits including elements such as transistors. In this case, after the first substrate and the second substrate, i.e., the device layer 1 and the device layer 2, are bonded together, the first substrate is removed. In the example of FIG. 6, a case will be described in which a semiconductor substrate having a porous layer formed using the anodization apparatus 1 according to this embodiment is used as the first substrate.

As shown in FIG. 6, first, the anodizing apparatus 1 of this embodiment is used to perform anodizing treatment on the first substrate 1000a, forming porous layers 1100 and 1200 on the surface (a).

Next, device layer 1 is formed on the surface of the first substrate on which the porous layers 1100 and 1200 are formed (b). Also, device layer 2 is formed on the second substrate 1000b (c).

Next, the first substrate 1000a and the second substrate 1000b are bonded together so that the device layer 1 and the device layer 2 face each other and are electrically connected to each other (d).

Next, the first substrate 1000a is peeled off from the device layer 1 (second substrate 1000b) using the porous layers 1100 and 1200 as peeling layers (e). The surface of the peeled first substrate 1000a is polished to remove the remaining porous layers 1100 and 1200 (f). This allows the first substrate 1000a with its surface polished to be reused.

Next, the porous layers 1100 and 1200 on the surface of the second substrate are removed (g). This results in the formation of the second substrate 1000b on which the device layers 1 and 2 are provided.

Here, the porous layers 1100 and 1200 have a hardness such that the porous layer does not peel off from the first substrate 1000a or break during the manufacturing process of the device layer 1 and the bonding process (d) of the first substrate 1000a and the second substrate 1000b. Furthermore, the porous layers 1100 and 1200 have a hardness such that they function as a peeling layer during the peeling process (e) of the first substrate 1000a and the second substrate 1000b. For example, in order to prevent peeling during the manufacturing process and bonding process of the device layer 1, it is preferable that the hardness of the porous layer 1200 (periphery) is higher than the hardness of the porous layer 1100 (center).

1.6 Effects of the present embodiment For example, in a semiconductor substrate lamination method, which is one of the methods for manufacturing a semiconductor device, if a semiconductor substrate without a porous layer is used, the mechanical strength of the semiconductor substrate is high, so peeling between the semiconductor substrate and the device layer formed thereon is difficult. Therefore, semiconductor substrates that are no longer needed are often removed by grinding or the like. In this case, the semiconductor substrate removed by grinding is discarded and cannot be reused. In addition, if a single layer of porous layer is provided between the semiconductor substrate and the device layer, the mechanical strength of the porous layer is low, so there is a high possibility that peeling or breakage of the porous layer will occur in the manufacturing process of the device layer or the lamination process of the semiconductor substrate.

In contrast, with the configuration according to this embodiment, the anodizing apparatus 1 can supply electrolytes A and B with different concentrations to the center and outer periphery of the semiconductor substrate surface. The anodizing apparatus 1 also has two upper electrodes 106 and 104 that correspond to the center and outer periphery of the semiconductor substrate surface, respectively, and can supply different amounts of current to each. Therefore, the anodizing apparatus 1 can form porous layers 1100 and 1200 with different film properties in the center and outer periphery of the semiconductor substrate surface.

By using the anodizing apparatus 1 of this embodiment to form porous layers 1100 and 1200 with different film properties at the center and periphery of the semiconductor substrate surface, for example, in a semiconductor substrate bonding method, it is possible to form porous layers 1100 and 1200 that function as peeling layers in a semiconductor substrate peeling process without peeling occurring in the device layer manufacturing process or the semiconductor substrate bonding process. This makes it possible to reuse the semiconductor substrate separated at the position of the porous layer.

2. Second embodiment Next, a second embodiment will be described. In the second embodiment, three examples of the configuration of the anodizing apparatus 1 that differs from the first embodiment will be described. The following description will focus on the differences from the first embodiment.

2.1 First Example First, an anodizing apparatus 1 according to a first example will be described. In the first example, a case will be described in which the upper electrode of the anodizing unit 10 is not divided. The overall configuration of the anodizing apparatus 1 of the first example is the same as that of the first embodiment shown in FIG.

Next, an example of the detailed configuration of the anodizing treatment unit 10 will be described with reference to Figures 7 and 8. Figure 7 is a perspective view of the anodizing treatment unit 10. Figure 8 is a cross-sectional view of the anodizing treatment unit 10 with electrolytes A and B being supplied. The examples of Figures 7 and 8 show a case in which the anodizing treatment unit 10 includes one upper electrode connected to one current source and two treatment tanks. Hereinafter, this configuration will also be referred to as "same electrode, single power source, split treatment tanks."

As shown in Figures 7 and 8, the anodizing treatment unit 10 includes treatment tanks 101 and 103, a vat 102, an upper electrode 104, a lower electrode 107, and a holding unit 108. That is, the anodizing treatment unit 10 of this example has a configuration in which the upper electrode is not divided, unlike Figures 2 and 3 of the first embodiment.

The upper electrode 104 functions as an anode in the anodization process using the treatment tanks 101 and 103. Therefore, the upper electrode 104 faces the treatment tanks 101 and 103. The outer diameter of the upper electrode 104 is approximately the same as the outer diameter of the treatment tank 101. In other words, the outer diameter of the upper electrode 104 is approximately the same as the semiconductor substrate 1000. The height position of the upper surface of the upper electrode 104 is higher than the upper end of the bath 102.

In this embodiment, the current supply unit 13 includes a current source 40. The current source 40 is connected to the upper electrode 104 and the lower electrode 107, and supplies a given current to the upper electrode 104 during anodization.

The other configurations, i.e., the configurations of the treatment tanks 101 and 103, the vat 102, etc., are the same as those in Figures 2 and 3 of the first embodiment.

2.2 Second Example Next, a description will be given of an anodizing apparatus 1 according to a second example. In the second example, a case will be described in which the treatment tank 103 of the anodizing unit 10 is omitted.

First, an example of the overall configuration of the anodizing apparatus 1 will be described with reference to FIG. 9. FIG. 9 is a block diagram of the anodizing apparatus 1.

As shown in FIG. 9, in the anodizing apparatus 1 of this embodiment, the electrolyte B supply unit 12 is eliminated. And, like the electrolyte B supply unit 12 in FIG. 1 of the first embodiment, the electrolyte A supply unit 11 has a circulation mechanism for circulating the electrolyte A between the electrolyte A mixing tank 20 and the anodizing treatment unit 10. More specifically, in the electrolyte A mixing tank 20, the liquid recovered from the anodizing treatment unit 10 through the pipe 16 is mixed with the three liquids A to C to generate the electrolyte A and adjust the concentration. The generated electrolyte A is supplied to the anodizing treatment unit 10 through the pipe 15. In addition, the electrolyte A mixing tank 20 has an overflow pipe for performing a drainage treatment when the liquid in the tank overflows. The electrolyte A supply unit 11 does not have to have a circulation mechanism for the electrolyte A. That is, it may have the same configuration as FIG. 1 of the first embodiment.

Next, an example of the detailed configuration of the anodizing unit 10 will be described with reference to Figures 10 and 11. Figure 10 is a perspective view of the anodizing unit 10. Figure 11 is a cross-sectional view of the anodizing unit 10 with electrolytic solution A being supplied. The example of Figures 10 and 11 shows a case where the anodizing unit 10 includes two upper electrodes 104 and 106 connected to one current source, and one treatment tank 101. Hereinafter, this configuration will also be referred to as "split electrodes, single power source, same treatment tank."

As shown in Figures 10 and 11, the anodizing treatment unit 10 includes a treatment tank 101, a vat 102, upper electrodes 104 and 106, an insulator 105, a lower electrode 107, and a holding unit 108. That is, the anodizing treatment unit 10 of this example is configured such that the treatment tank 103 is eliminated from the first embodiment shown in Figures 2 and 3. In this example, the pipes 17 and 19 that were connected to the treatment tank 103 are also eliminated.

The upper electrode 104 functions as an anode when forming the porous layer 1200 in the anodizing process. The upper electrode 106 functions as an anode when forming the porous layer 1100 in the anodizing process.

In this example, the upper electrode 104 is connected to the current source 40 via switch SW1. The upper electrode 106 is connected to the current source 40 via switch SW2.

As shown in FIG. 11, in this example, the treatment tank 103 is not used, so there is no gap GP2. During anodization, the pipe 18 is closed. Therefore, the excess electrolyte A in the treatment tank 101 flows through the gap GP1 into the vat 102.

The other configurations, i.e., the configurations relating to the treatment tank 101, the vat 102, and the upper electrodes 104 and 106, are the same as those in Figures 2 and 3 of the first embodiment.

2.3 Third Example Next, an anodizing apparatus 1 according to a third example will be described. In the third example, unlike the second example of the second embodiment, a current source is provided for each of the upper electrodes 104 and 106. The overall configuration of the anodizing apparatus 1 of the third example is the same as that of the second example of the second embodiment shown in FIG. 9.

Next, an example of the detailed configuration of the anodizing treatment unit 10 will be described with reference to Figures 12 and 13. Figure 12 is a perspective view of the anodizing treatment unit 10. Figure 13 is a cross-sectional view of the anodizing treatment unit 10 when electrolytic solution A is being supplied. The examples of Figures 12 and 13 show a case in which the anodizing treatment unit 10 includes two upper electrodes connected to different current sources, and one treatment tank. Hereinafter, this configuration will also be referred to as "split electrodes, multiple power sources, same treatment tank."

As shown in Figures 12 and 13, the configuration of the anodizing treatment unit 10 is similar to that of the second example of the second embodiment shown in Figures 10 and 11.

In this example, as in Figures 2 and 3 of the first embodiment, the upper electrode 104 is connected to a current source 40. Also, the upper electrode 106 is connected to a current source 41.

2.4 Effects of this embodiment With the configuration of this embodiment, the same effects as in the first embodiment can be obtained.

3. Third embodiment Next, a third embodiment will be described. In the third embodiment, six examples of anodizing methods using the anodizing apparatus 1 will be described. The following description will focus on the differences from the first and second embodiments.

3.1 First Example First, the method of anodizing according to the first example will be described with reference to Fig. 14. Fig. 14 is a flow chart showing the method of anodizing according to the first example. In the first example, an example of forming the porous layer 1100 and the porous layer 1200 at different timings using the anodizing apparatus 1 described in the first example of the first embodiment or the second embodiment will be described.

As shown in FIG. 14, the semiconductor substrate 1000 that has been brought into the anodizing apparatus 1 is fixed by the holding portion 108 (step S10).

Next, the electrolyte A supply unit 11 generates electrolyte A and supplies it to the treatment tank 103 (step S11).

Next, the control circuit 14 performs anodization of the center of the semiconductor substrate 1000 (step S12). That is, the control circuit 14 forms a porous layer 1100. More specifically, for example, in the case of the anodization apparatus 1 according to the first embodiment, a current is supplied from the current source 41 to the upper electrode 106, and anodization is performed. Also, for example, in the case of the anodization apparatus 1 according to the first example of the second embodiment, a current is supplied from the current source 40 to the upper electrode 104. At this time, the electrolyte B is not supplied to the treatment tank 101. Therefore, the porous layer 1100 is formed, and the porous layer 1200 is not formed.

Next, the control circuit 14 discharges the electrolyte A from the treatment tank 103 via the pipe 19 (step S13).

Next, the electrolyte B supply unit 12 generates electrolyte B and supplies it to the treatment tank 101 (step S14).

Next, the control circuit 14 performs anodization of the outer periphery of the semiconductor substrate 1000 (step S15). That is, the control circuit 14 forms a porous layer 1200. More specifically, for example, in the case of the anodization apparatus 1 according to the first embodiment, a current is supplied from the current source 40 to the upper electrode 104, and anodization is performed. Also, for example, in the case of the anodization apparatus 1 according to the first example of the second embodiment, a current is supplied from the current source 40 to the upper electrode 104. At this time, the electrolyte A is not supplied to the treatment tank 103. Therefore, the porous layer 1200 is formed, and the porous layer 1100 is not formed.

Next, the control circuit 14 discharges the electrolyte B from the treatment tank 101 via the pipe 18 (step S16).

The semiconductor substrate 1000 is removed from the anodizing device 1, and the anodizing process is completed (step S17).

In this example, the case where the porous layer 1200 is formed after the porous layer 1100 is formed has been described, but the porous layer 1200 may be formed before the porous layer 1100 is formed.

3.2 Second Example Next, a method of anodizing according to a second example will be described with reference to Fig. 15. Fig. 15 is a flow chart showing a method of anodizing according to the second example. In the second example, an example of forming the porous layer 1100 and the porous layer 1200 at the same time using the anodizing apparatus 1 described in the first example of the first embodiment or the second embodiment will be described.

As shown in FIG. 15, the semiconductor substrate 1000 is carried into the anodizing apparatus 1 and fixed by the holding portion 108 (step S10).

Next, the electrolyte A supply unit 11 generates electrolyte A and supplies it to the treatment tank 103. The electrolyte B supply unit 12 generates electrolyte B and supplies it to the treatment tank 101 (step S21).

Next, the control circuit 14 performs anodization of the semiconductor substrate 1000 (step S22). That is, the control circuit 14 forms the porous layers 1100 and 1200. More specifically, for example, in the case of the anodization apparatus 1 according to the first embodiment, the current source 40 supplies a current to the upper electrode 104, and the current source 41 supplies a current to the upper electrode 106. Also, for example, in the case of the anodization apparatus 1 according to the first example of the second embodiment, a current is supplied from the current source 40 to the upper electrode 104. As a result, the porous layers 1100 and 1200 are formed at the same time.

Next, the control circuit 14 discharges the electrolyte A from the treatment tank 103 via the pipe 19. The control circuit 14 also discharges the electrolyte B from the treatment tank 101 via the pipe 18 (step S23).

The semiconductor substrate 1000 is removed from the anodizing device 1, and the anodizing process is completed (step S17).

3.3 Third Example Next, a method of anodizing according to a third example will be described with reference to Fig. 16. Fig. 16 is a flow chart showing a method of anodizing according to the third example. In the third example, an example of forming the porous layer 1100 and the porous layer 1200 at different timings using the anodizing apparatus 1 described in the second example of the second embodiment will be described.

As shown in FIG. 16, the semiconductor substrate 1000 that has been brought into the anodizing apparatus 1 is fixed by the holding portion 108 (step S10).

Next, the electrolyte A supply unit 11 generates electrolyte A and supplies it to the treatment tank 101 (step S31).

Next, the control circuit 14 turns on one of the switches SW1 and SW2 to perform anodization (step S32). When the control circuit 14 turns on the switch SW2, a current is supplied from the current source 40 to the upper electrode 106, and the porous layer 1100 is formed. Alternatively, when the control circuit 14 turns on the switch SW1, a current is supplied from the current source 40 to the upper electrode 104, and the porous layer 1200 is formed.

Next, the control circuit 14 turns on the other of the switches SW1 and SW2 that were not turned on in step S32, and performs anodization (step S33). This forms either the porous layer 1100 or the porous layer 1200 that was not formed in step S32.

Next, the control circuit 14 discharges the electrolyte A from the treatment tank 101 through the pipe 18 (step S34).

The semiconductor substrate 1000 is removed from the anodizing device 1, and the anodizing process is completed (step S17).

In this example, the order in which the porous layers 1100 and 1200 are formed can be set arbitrarily.

3.4 Fourth Example Next, a method of anodizing according to a fourth example will be described with reference to Fig. 17. Fig. 17 is a flow chart showing a method of anodizing according to the fourth example. In the fourth example, an example of forming the porous layer 1100 and the porous layer 1200 at different timings using the anodizing apparatus 1 described in the third example of the second embodiment will be described.

As shown in FIG. 17, the semiconductor substrate 1000 that has been brought into the anodizing apparatus 1 is fixed by the holding portion 108 (step S10).

Next, the electrolyte A supply unit 11 generates electrolyte A and supplies it to the treatment tank 101 (step S41).

Next, the control circuit 14 supplies current from one of the current sources 40 and 41 to the corresponding upper electrode to perform anodization on one of the central and peripheral portions of the semiconductor substrate 1000 (step S42). When a current is supplied from the current source 41 to the upper electrode 106, a porous layer 1100 is formed. Alternatively, when a current is supplied from the current source 40 to the upper electrode 104, a porous layer 1200 is formed.

Next, the control circuit 14 supplies current from the other of the current sources 40 and 41 that were not used in step S42 to the corresponding upper electrode, and performs anodization on the other of the central and peripheral parts of the semiconductor substrate 1000 (step S43). This forms either the porous layer 1100 or the porous layer 1200 that was not formed in step S42.

Next, the control circuit 14 discharges the electrolyte A from the treatment tank 101 via the pipe 18 (step S44).

The semiconductor substrate 1000 is removed from the anodizing device 1, and the anodizing process is completed (step S17).

In this example, the order in which the porous layers 1100 and 1200 are formed can be set arbitrarily.

3.5 Fifth Example Next, a method of anodizing according to a fifth example will be described with reference to Fig. 18. Fig. 18 is a flow chart showing a method of anodizing according to the fifth example. In the fifth example, an example of forming the porous layer 1100 and the porous layer 1200 at the same time using the anodizing apparatus 1 described in the third example of the second embodiment will be described.

As shown in FIG. 18, the semiconductor substrate 1000 that has been brought into the anodizing apparatus 1 is fixed by the holding portion 108 (step S10).

Next, the electrolyte A supply unit 11 generates electrolyte A and supplies it to the treatment tank 101 (step S51).

Next, the control circuit 14 supplies currents of different magnitudes from the current sources 40 and 41 to the corresponding upper electrodes 104 and 106 to perform anodization (step S52). This results in the porous layers 1100 and 1200 being formed simultaneously.

Next, the control circuit 14 discharges the electrolyte A from the treatment tank 101 through the pipe 18 (step S53).

The semiconductor substrate 1000 is removed from the anodizing device 1, and the anodizing process is completed (step S17).

3.6 Sixth Example Next, a method of anodizing according to a sixth example will be described with reference to Fig. 19. Fig. 19 is a flow chart showing a method of anodizing according to the sixth example. In the sixth example, an example of forming the porous layer 1100 and the porous layer 1200 at the same time using the anodizing apparatus 1 described in the first embodiment will be described.

As shown in FIG. 19, the semiconductor substrate 1000 that has been brought into the anodizing apparatus 1 is fixed by the holding portion 108 (step S10).

Next, the electrolyte B supply unit 12 generates electrolyte B and supplies it to the treatment tank 101. In addition, the electrolyte A supply unit 11 generates electrolyte A, which has a different concentration from electrolyte B, and supplies it to the treatment tank 103 (step S61).

Next, the control circuit 14 supplies currents of different magnitudes from the current sources 40 and 41 to the corresponding upper electrodes 104 and 106 to perform anodization (step S62). That is, in this example, the control circuit 14 performs anodization under conditions of different electrolyte concentrations and current amounts. As a result, the porous layers 1100 and 1200 are formed at the same time.

Next, the control circuit 14 discharges the electrolyte A from the treatment tank 103 via the pipe 19. The control circuit 14 also discharges the electrolyte B from the treatment tank 101 via the pipe 18 (step S63).

The semiconductor substrate 1000 is removed from the anodizing device 1, and the anodizing process is completed (step S17).

3.7 Effects of this embodiment The first to sixth examples of this embodiment can be implemented by the anodizing apparatus 1 described in the first and second embodiments.

4. Fourth embodiment Next, a fourth embodiment will be described. In the fourth embodiment, four examples of the configuration of the electrolyte A supply unit 11 and the electrolyte B supply unit 12 that are different from those of the first embodiment will be described. The following description will focus on the differences from the first to third embodiments.

4.1 First Example First, an anodizing apparatus 1 according to a first example will be described with reference to Fig. 20. Fig. 20 is a block diagram of the anodizing apparatus 1. In the first example, unlike the first embodiment, a case will be described in which the electrolytic solution B supply unit 12 does not have a circulation mechanism for the electrolytic solution B.

As shown in FIG. 20, the anodizing device 1 of this example includes an anodizing processing section 10, an electrolyte A supply unit 11, an electrolyte B supply unit 12, a current supply unit 13, a control circuit 14, and a concentration sensor 50.

The configuration of the electrolyte A supply unit 11 is similar to that of the electrolyte A supply unit 11 in FIG. 1 of the first embodiment.

Like the electrolyte A supply unit 11, the electrolyte B supply unit 12 does not have a circulation mechanism and supplies unused electrolyte B to the anodization processing unit 10. That is, the electrolyte B supply unit 12 mixes three liquids D to F in the electrolyte B mixing tank 30 to produce electrolyte B.

The pipe 16 is not connected to the electrolyte B mixing tank 30, and the liquid used in the anodizing treatment unit 10 (i.e., the liquid recovered from the vat 102) is discharged as wastewater.

The concentration sensor 50 monitors the concentration of the wastewater (mixture of electrolyte A and electrolyte B) in the pipe 16 and transmits the result to the control circuit 14. For example, in the anodizing device 1 of this example, the supply of new electrolytes A and B and the wastewater treatment are repeated for each anodizing treatment. However, if the result of the concentration monitoring of the wastewater by the concentration sensor 50 determines that the electrolytes A and B in the treatment tanks 101 and 103 can be reused in the next anodizing treatment, all or part of the electrolytes A and B in the treatment tanks 101 and 103 can be reused. When part of the electrolytes A and B are reused, the shortage of electrolytes A and B is supplied from the electrolyte A supply unit 11 and the electrolyte B supply unit 12, respectively.

4.2 Second Example Next, an anodizing apparatus 1 according to a second example will be described with reference to Fig. 21. Fig. 21 is a block diagram of the anodizing apparatus 1. In the second example, a case will be described in which the electrolytic solution A supply unit 11 and the electrolytic solution B supply unit 12 have a circulation mechanism for the electrolytic solutions.

As shown in FIG. 21, the anodizing device 1 of this example includes an anodizing processing section 10, an electrolyte A supply unit 11, an electrolyte B supply unit 12, a current supply unit 13, and a control circuit 14.

The configuration of the electrolyte B supply unit 12 is the same as that of the electrolyte B supply unit 12 in FIG. 1 of the first embodiment. In other words, electrolyte B is collected from the treatment tank 101 via the pipe 16.

The electrolyte A supply unit 11, like the electrolyte B supply unit 12, adjusts the composition of the liquid (a mixture of electrolyte A and electrolyte B) recovered from the vat 102 in the anodizing treatment unit 10 via the piping 16, and supplies it again to the treatment tank 103 of the anodizing treatment unit 10.

4.3 Third Example Next, an anodizing apparatus 1 according to a third example will be described with reference to Fig. 22. Fig. 22 is a block diagram of the anodizing apparatus 1. Unlike the second example, the third example will be described in which the electrolytic solution A supply unit 11 recovers the electrolytic solution A from the treatment tank 103 via the pipe 19.

As shown in FIG. 22, the anodizing device 1 of this example includes an anodizing processing section 10, an electrolyte A supply unit 11, an electrolyte B supply unit 12, a current supply unit 13, and a control circuit 14.

The electrolyte A mixing tank 20 of the electrolyte A supply unit 11 in this example is connected to the treatment tank 103 of the anodizing unit 10 via piping 19. That is, the electrolyte A supply unit 11 adjusts the components of the electrolyte A recovered from the treatment tank 103 and supplies it again to the treatment tank 103 of the anodizing unit 10. The other configuration is the same as that of the second example of the fourth embodiment shown in FIG. 21.

4.4 Fourth Example Next, an anodizing apparatus 1 according to a fourth example will be described with reference to Fig. 23. Fig. 23 is a block diagram of the anodizing apparatus 1. In the fourth example, unlike the first embodiment, the electrolytic solution A supplying unit 11 has a circulation mechanism, and the electrolytic solution B supplying unit 12 does not have a circulation mechanism.

As shown in FIG. 23, the anodizing device 1 of this example includes an anodizing processing section 10, an electrolyte A supply unit 11, an electrolyte B supply unit 12, a current supply unit 13, and a control circuit 14.

The electrolyte A mixing tank 20 of the electrolyte A supply unit 11 in this example, as in FIG. 21 of the second example of the fourth embodiment, adjusts the components of the liquid (a mixture of electrolyte A and electrolyte B) recovered from the vat 102 in the anodizing treatment unit 10 via the piping 16, and supplies it again to the treatment tank 103 of the anodizing treatment unit 10.

The electrolyte B supply unit 12, like the first example of the fourth embodiment shown in FIG. 20, does not have a circulation mechanism and supplies unused electrolyte B to the anodization processing unit 10. That is, the electrolyte B supply unit 12 mixes three liquids D to F in the electrolyte B mixing tank 30 to produce electrolyte B.

4.5 Effects of this embodiment With the configuration of this embodiment, the same effects as those of the first to third embodiments can be obtained.

The anodizing treatment unit 10 described in the first and second examples of the second embodiment can be applied to the first to fourth examples of this embodiment. Also, the anodizing treatment method described in the first, second, and sixth examples of the third embodiment can be performed in the first to fourth examples of this embodiment.

5. Fifth embodiment Next, a fifth embodiment will be described. In the fifth embodiment, four examples of the configuration of the anodizing apparatus 1 different from the first to fourth embodiments will be described. The anodizing apparatus 1 of this embodiment has a mechanism for supplying an electrolyte between the upper electrode and the upper surface (surface not anodized) of the semiconductor substrate 1000. The following description will focus on the differences from the first to fourth embodiments.

5.1 First Example 5.1.1 Overall Configuration First, the overall configuration of the anodizing apparatus 1 of the first example will be described with reference to Fig. 24. Fig. 24 is a block diagram of the anodizing apparatus. Note that the electrolytic solution A supply unit 11 and the electrolytic solution B supply unit 12 of this embodiment have the same configuration as those of the first embodiment. Therefore, in the example of Fig. 24, details of the components of the electrolytic solution A supply unit 11 and the electrolytic solution B supply unit 12 are omitted.

As shown in FIG. 24, the anodizing device 1 includes an anodizing processing section 10, an electrolyte A supply unit 11, an electrolyte B supply unit 12, an electrolyte C supply unit 61, a current supply unit 13, and a control circuit 14.

The anodizing unit 10 includes multiple treatment tanks and multiple electrodes, and performs anodizing on the surface of the semiconductor substrate. The configuration of the anodizing unit 10 will be described later.

The electrolyte A supply unit 11, electrolyte B supply unit 12, and current supply unit 13 are the same as those in FIG. 1 of the first embodiment.

The electrolyte C supply unit 61 supplies electrolyte C to a treatment tank provided between the upper electrode in the anodizing treatment unit 10 and the upper surface (surface not anodized) of the semiconductor substrate 1000. The electrolyte C supply unit 61 has a mechanism (e.g., a pump, etc.) not shown for adjusting the liquid pressure of the electrolyte C supplied to the treatment tank. For example, a solution that hardly reacts with the semiconductor substrate 1000 (does not dissolve Si) during anodizing treatment is used as the electrolyte C. In order to suppress metal contamination of the semiconductor substrate 1000, it is preferable that the electrolyte C does not contain metal elements. The electrolyte C supply unit 61 of this embodiment has a function for circulating the electrolyte C between the anodizing treatment unit 10 and the electrolyte C mixing tank 70. That is, the electrolyte C supply unit 61 adjusts the components of the liquid recovered from the anodizing treatment unit 10 via the piping 64 and supplies it again to the anodizing treatment unit 10.

The electrolyte C supply unit 61 includes an electrolyte C mixing tank 70, a supply control unit 71, multiple liquid supply units 72 (three liquid supply units 72a to 72c in the example of FIG. 24), and a concentration sensor 73.

The electrolyte C mixing tank 70 is a tank for mixing a plurality of liquids to generate the electrolyte C. The electrolyte C supply unit 61 generates the electrolyte C by mixing, for example, three liquids G to I as raw materials. The liquids used to generate the electrolyte C are not limited to three types. In addition, materials other than liquids may be used to generate the electrolyte C. For example, the electrolyte C may be a diluted HF aqueous solution that hardly reacts with the semiconductor substrate 1000 during anodization, a diluted HCl aqueous solution, or a non-aqueous organic electrolyte. For example, at least one of acetonitrile, propylene carbonate, or dimethylformamide, which are non-aqueous electrolytes, may be selected as the raw material for the electrolyte C. In addition, at least one of anhydrous HF, tetrafluoroborate, or lithium fluoroborate, which are fluoride sources, may be selected as the raw material for the electrolyte C. The generated electrolyte C is supplied to the treatment tank in the anodizing unit 10 through the pipe 63. The electrolyte C mixing tank 70 also has an overflow pipe for draining the liquid in the tank if the liquid overflows.

The supply control unit 71 controls the supply amounts of liquids G to I supplied to the electrolyte C mixing tank 70 under the control of the control circuit 14. For example, the supply control unit 71 includes valves and flow meters provided in the supply lines of each liquid.

The liquid supply units 72a to 72c are each connected to the electrolyte C mixing tank 70 by a supply line (piping). The liquid supply units 72a to 72c each supply liquids G to I to the electrolyte C mixing tank 70 via the supply line. The liquid supply units 72a to 72c may each have a mechanism for pumping the liquids G to I from the containers of the liquids G to I, for example.

The concentration sensor 73 monitors the concentration of the electrolyte C in the electrolyte C mixing tank 70 and transmits the result to the control circuit 14. Based on the result of the concentration monitoring, the control circuit 14 controls the supply control unit 71 to adjust the concentration of the electrolyte C. The concentration sensor 73 may also measure the resistance value of the electrolyte C.

The control circuit 14 controls the entire anodizing apparatus 1. More specifically, the control circuit 14 controls the anodizing processing section 10, the electrolyte A supply unit 11, the electrolyte B supply unit 12, the electrolyte C supply unit 61, and the current supply unit 13.

5.1.2 Detailed Configuration of Anodizing Unit Next, an example of the detailed configuration of the anodizing unit 10 will be described with reference to Fig. 25. Fig. 25 is a cross-sectional view of the anodizing unit 10 in a state in which electrolytic solutions A to C are being supplied. The example of Fig. 25 shows a case in which the anodizing apparatus 1 has a "split electrode, multiple power sources, and split treatment tank" configuration, as in the first embodiment.

As shown in FIG. 25, the anodization treatment unit 10 includes treatment tanks 101, 103, and 111, a vat 102, upper electrodes 104 and 106, an insulator 105, a lower electrode 107, and a holding unit 108. The configurations of the treatment tanks 101 and 103, the vat 102, upper electrodes 104 and 106, the insulator 105, and the lower electrode 107 are the same as those in FIG. 2 of the first embodiment. As in the first embodiment, a current source 40 is connected to the upper electrode 104. A current source 41 is connected to the upper electrode 106.

The treatment tank 111 has, for example, a cylindrical shape. The upper end of the treatment tank 111 is located on the lower surface of the upper electrodes 104 and 106. During anodization, the lower end of the treatment tank 111 is located on the upper surface of the semiconductor substrate 1000 (the surface that is not anodized). The outer periphery of the treatment tank 111 is surrounded by the side of the holding part 108. That is, the area surrounded by the lower surfaces of the upper electrodes 104 and 106, the upper surface of the semiconductor substrate 1000, and the side of the holding part 108 corresponds to the treatment tank 111. In other words, the treatment tank 111 is provided between the upper electrodes 104 and 106 and the treatment tanks 101 and 103. Pipes 63 and 64 are connected to the treatment tank 111. Pipe 63 is a liquid supply line to the treatment tank 111. Pipe 64 is a liquid discharge line from the treatment tank 111. In this embodiment, pipe 63 is connected to the liquid supply line of the electrolyte C mixing tank 70. Pipe 64 is connected to the liquid recovery line of electrolyte C mixing tank 70. Note that multiple pipes 63 and 64 may be provided. Furthermore, a waste liquid discharge pipe used to discharge the liquid in treatment tank 111 as waste liquid may be connected to treatment tank 111.

The holding portion 108 in this embodiment has, for example, a cylindrical shape. The upper electrode 104 contacts the inner surface of the holding portion 108 near the upper end. In the first and second embodiments, an L-shaped hook portion that contacts the lower surface of the semiconductor substrate 1000 is provided at the lower end of the holding portion 108. In this case, the semiconductor substrate 1000 is fixed by being sandwiched between the upper electrode and the hook portion. In contrast, in this example, the hook portion that contacts the lower surface of the semiconductor substrate 1000 is eliminated. The holding portion 108 includes a fixing portion 113. The fixing portion 113 is provided on the side of the holding portion 108. During anodization, the semiconductor substrate 1000 is pressed against the fixing portion 113 from below by the liquid pressure of the electrolytes A and B. The holding portion 108 and the fixing portion 113 are made of an insulating material that is resistant to the electrolyte C. For example, an elastic material may be used for the holding portion 108 and the fixing portion 113 to improve the sealing property with the semiconductor substrate 1000. The cross-sectional shape of the fixing part 113 is arbitrary. For example, the cross-sectional shape of the fixing part 113 may be semicircular or rectangular.

In this embodiment, the liquid pressure of electrolytes A and B is set higher than the liquid pressure of electrolyte C. Therefore, during anodization, the liquid pressure of electrolytes A and B presses the upper surface of the semiconductor substrate 1000 against the fixing portion 113.

There is no fixing portion 113 between the lower surface of the semiconductor substrate 1000 (the surface to be anodized) and the lower electrode 107. In other words, the lower surface of the semiconductor substrate 1000 is not in contact with the holding portion 108. Therefore, during anodization, no area that is not anodized (hereinafter also referred to as "edge cut area") is provided on the outer periphery of the lower surface of the semiconductor substrate 1000. Therefore, porous layers 1100 and 1200 are formed over the entire lower surface of the semiconductor substrate 1000.

5.1.3 Configuration of Contact Portion Next, an example of the configuration of the fixed portion 113 will be described with reference to Fig. 26. Fig. 26 is a top view of the fixed portion 113.

As shown in FIG. 26, the fixing portion 113 in this embodiment has a ring shape. During anodization, the entire outer periphery (edge) of the upper surface of the semiconductor substrate 1000 contacts the fixing portion 113. This prevents liquid from seeping out from the treatment tank 101 into the treatment tank 111.

5.2 Second Example Next, a second example will be described. In the second example, the configuration of the anodizing unit 10, which is different from that of the first example, will be described with reference to FIG. 27. FIG. 27 is a cross-sectional view of the anodizing unit 10 in a state in which electrolytic solutions A to C are being supplied. The example of FIG. 27 shows a case in which the anodizing apparatus 1 has a "same electrode, single power source, divided treatment tank" configuration, similar to the first example of the second embodiment.

The overall configuration of the anodizing apparatus 1 in this example is the same as that shown in FIG. 24 of the first example of the fifth embodiment.

As shown in FIG. 27, the anodization processing unit 10 includes processing tanks 101, 103, and 111, a vat 102, an upper electrode 104, a lower electrode 107, and a holding unit 108.

The treatment tanks 101 and 103, the vat 102, the upper electrode 104, and the lower electrode 107 are the same as those in the first example of the second embodiment shown in FIG. 8. As in the first example of the second embodiment, the current supply unit 13 (current source 40) is connected to the upper electrode 104.

In this example, the area surrounded by the lower surface of the upper electrode 104, the upper surface of the semiconductor substrate 1000, and the side surface of the holding portion 108 corresponds to the processing tank 111. In other words, the processing tank 111 is provided between the upper electrode 104 and the processing tanks 101 and 103.

5.3 Third Example Next, a third example will be described. In the third example, the configuration of the anodizing apparatus 1, which is different from the first and second examples, will be described with reference to Figs. 28 and 29. Fig. 28 is a block diagram of the anodizing apparatus. Fig. 29 is a cross-sectional view of the anodizing processing section 10 in a state in which electrolytic solutions A and C are being supplied. The example of Fig. 29 shows a case in which the anodizing apparatus 1 has a "split electrode, single power source, same processing tank" configuration, similar to the second example of the second embodiment.

As shown in FIG. 28, the anodizing apparatus 1 of this example has a configuration in which the electrolyte B supply unit 12 and the pipes 16 and 17 have been eliminated from the configuration of the first example of the fifth embodiment (FIG. 24). The electrolyte A mixing tank 20 of the electrolyte A supply unit 11 is connected to the treatment tank 101 in the anodizing treatment unit 10 via the pipe 15.

As shown in FIG. 29, the anodization treatment unit 10 includes treatment tanks 101 and 111, a bath 102, upper electrodes 104 and 106, an insulator 105, a lower electrode 107, and a holding unit 108.

The treatment tank 101, the vat 102, the upper electrodes 104 and 106, the insulator 105, and the lower electrode 107 are the same as those in FIG. 11 of the second example of the second embodiment. As in the second example of the second embodiment, in this example, the upper electrode 104 is connected to the current source 40 via the switch SW1. Also, the upper electrode 106 is connected to the current source 40 via the switch SW2.

In this example, the area surrounded by the lower surfaces of the upper electrodes 104 and 106, the upper surface of the semiconductor substrate 1000, and the side surface of the holding portion 108 corresponds to the processing tank 111. In other words, the processing tank 111 is provided between the upper electrodes 104 and 106 and the processing tank 101.

5.4 Fourth Example Next, a fourth example will be described. In the fourth example, the configuration of the anodizing unit 10, which is different from that of the third example, will be described with reference to FIG. 30. FIG. 30 is a cross-sectional view of the anodizing unit 10 in a state in which electrolytic solutions A to C are being supplied. The example of FIG. 30 shows a case in which the anodizing apparatus 1 has a "split electrode, multiple power sources, and the same treatment tank" configuration, similar to the third example of the second embodiment.

The overall configuration of the anodizing apparatus 1 in this example is similar to that of the third example of the fifth embodiment shown in FIG. 28.

As shown in FIG. 30, the anodization treatment unit 10 includes treatment tanks 101 and 111, a bath 102, upper electrodes 104 and 106, an insulator 105, a lower electrode 107, and a holding unit 108.

The treatment tank 101, the vat 102, the upper electrodes 104 and 106, the insulator 105, and the lower electrode 107 are the same as those in the third example of the second embodiment shown in FIG. 13. As in the third example of the second embodiment, the upper electrode 104 is connected to a current source 40. The upper electrode 106 is connected to a current source 41.

The configuration of the treatment tank 111 is similar to that of the third example of the fifth embodiment shown in Figure 29.

5.5 Effects of this embodiment With the configuration of this embodiment, the same effects as those of the first to fourth embodiments can be obtained.

Furthermore, with the configuration according to this embodiment, the anodizing apparatus can supply an electrolyte between the upper electrode and the semiconductor substrate. This can reduce the contact area between the upper electrode and the semiconductor substrate. This can reduce metal contamination of the semiconductor substrate by the upper electrode.

Furthermore, with the configuration according to this embodiment, poor electrical continuity between the upper electrode and the semiconductor substrate can be suppressed by supplying an electrolyte between the upper electrode and the semiconductor substrate.

6. Sixth embodiment Next, a sixth embodiment will be described. In the sixth embodiment, a configuration of an electrolytic solution C supply unit 61 different from that of the first example of the fifth embodiment will be described.

6.1 Overall Configuration The overall configuration of the anodizing apparatus 1 will be described with reference to Fig. 31. Fig. 31 is a block diagram of the anodizing apparatus 1.

As shown in FIG. 31, the anodizing apparatus 1 of this example includes an anodizing processing section 10, an electrolyte A supply unit 11, an electrolyte B supply unit 12, an electrolyte C supply unit 61, a current supply unit 13, a control circuit 14, and a concentration sensor 91.

The anodizing unit 10, electrolyte A supply unit 11, electrolyte B supply unit 12, current supply unit 13, and control circuit 14 are the same as those in the first example of the fifth embodiment shown in FIG. 24.

The electrolyte C supply unit 61 does not have a circulation mechanism and supplies unused electrolyte C to the anodization processing unit 10. That is, the electrolyte C supply unit 61 mixes three liquids G to I in the electrolyte C mixing tank 70 to produce electrolyte C.

The pipe 64 is not connected to the electrolyte C mixing tank 70, and the liquid used in the treatment tank 111 is discharged as waste liquid.

The concentration sensor 91 monitors the concentration of the wastewater in the pipe 64 and transmits the result to the control circuit 14. For example, in the anodizing device 1 of this embodiment, the supply of new electrolyte C and the wastewater treatment are repeated for each anodizing treatment. However, if the monitoring result of the concentration sensor 91 determines that the electrolyte C in the treatment tank 111 can be reused in the next anodizing treatment, the anodizing device 1 can reuse all or a portion of the electrolyte C in the treatment tank 111. When a portion of the electrolyte C is reused, the shortage of electrolyte C is supplied from the electrolyte C supply unit 61.

6.2 Effects of this embodiment This embodiment can be applied to the fifth embodiment.

7. Seventh embodiment Next, the seventh embodiment will be described. In the seventh embodiment, four examples will be described in which two types of electrolyte solutions are supplied between the upper electrode and the upper surface of the semiconductor substrate. The following description will focus on the differences from the fifth and sixth embodiments.

7.1 First Example 7.1.1 Overall Configuration First, the overall configuration of the anodizing apparatus 1 of the first example will be described with reference to Fig. 32. Fig. 32 is a block diagram of the anodizing apparatus. Note that in the example of Fig. 32, details of the components of the electrolytic solution A supply unit 11 and the electrolytic solution B supply unit 12 are omitted.

As shown in FIG. 32, the anodizing device 1 includes an anodizing processing section 10, an electrolyte A supply unit 11, an electrolyte B supply unit 12, an electrolyte C supply unit 61, an electrolyte D supply unit 62, a current supply unit 13, and a control circuit 14.

The anodizing treatment unit 10 has two treatment tanks between the upper electrode and the semiconductor substrate 1000. Details of the anodizing treatment unit 10 will be described later.

The electrolyte A supply unit 11, electrolyte B supply unit 12, and current supply unit 13 are the same as those in FIG. 1 of the first embodiment.

The configuration of the electrolyte C supply unit 61 is the same as that of the first example of the fifth embodiment shown in FIG. 24. The electrolyte C mixing tank 70 is connected to the anodizing treatment unit 10 via pipes 65 and 66. That is, the electrolyte C supply unit 61 supplies electrolyte C to the anodizing treatment unit 10 via pipe 65 and recovers liquid from the anodizing treatment unit 10 via pipe 66.

The electrolyte D supply unit 62 supplies electrolyte D to a treatment tank provided between the upper electrode in the anodizing treatment unit 10 and the upper surface (surface not anodized) of the semiconductor substrate 1000. The electrolyte D supply unit 62 has a mechanism (e.g., a pump, etc.) not shown for adjusting the liquid pressure of the electrolyte D supplied to the treatment tank. For example, a solution that hardly reacts with the semiconductor substrate 1000 during anodizing is used as the electrolyte D. In order to suppress metal contamination of the semiconductor substrate 1000, it is preferable that the electrolyte D does not contain metal elements. The electrolyte D may be the same as the electrolyte C or may be different. In the following, a case will be described in which the electrolyte D has a different concentration (resistance value) from the electrolyte C. The resistance value of the electrolyte D may be higher or lower than that of the electrolyte C. The resistance values of the electrolytes C and D are adjusted taking into consideration the material of the upper electrodes 104 and 106, the effect on the anodizing treatment by the combination of the electrolytes A to D (influence on the electric field), and the like. The electrolyte D supply unit 62 of this embodiment has the function of circulating electrolyte D between the anodizing treatment unit 10 and the electrolyte D mixing tank 80. In other words, the electrolyte D supply unit 62 adjusts the components of the liquid recovered from the anodizing treatment unit 10 and supplies it again to the anodizing treatment unit 10.

The electrolyte D supply unit 62 includes an electrolyte D mixing tank 80, a supply control unit 81, multiple liquid supply units 82 (three liquid supply units 82a to 82c in the example of FIG. 24), and a concentration sensor 83.

The electrolyte D mixing tank 80 is a tank for mixing a plurality of liquids to generate the electrolyte D. The electrolyte D supply unit 62 can generate and adjust the concentration of the electrolyte D by mixing the liquid recovered from the anodization processing unit 10 via the pipe 64 as a raw material with the three liquids J to L. The liquids used to generate the electrolyte D are not limited to three types. In addition, materials other than liquids may be used to generate the electrolyte D. As with the electrolyte C, the electrolyte D may be, for example, a diluted HF aqueous solution that hardly reacts with the semiconductor substrate 1000 during the anodization process, a diluted HCl aqueous solution, or a non-water-soluble organic electrolyte. For example, at least one of acetonitrile, propylene carbonate, or dimethylformamide, which are non-water-soluble electrolytes, may be selected as the raw material for the electrolyte D. In addition, at least one of anhydrous HF, tetrafluoroborate, or lithium fluoroborate, which are fluoride sources, may be selected as the raw material for electrolyte D. The generated electrolyte D is supplied to one of the treatment tanks of the anodization treatment unit 10 through piping 63. In addition, the electrolyte D mixing tank 80 has an overflow pipe for draining the liquid when the liquid in the tank overflows.

The supply control unit 81 controls the supply amounts of liquids J to L supplied to the electrolyte D mixing tank 80 under the control of the control circuit 14. For example, the supply control unit 81 includes valves and flow meters provided in the supply lines of each liquid.

The liquid supply units 82a to 82c are each connected to the electrolyte D mixing tank 80 by a supply line. The liquid supply units 82a to 82c each supply liquids J to L to the electrolyte D mixing tank 80 via the supply line. The liquid supply units 82a to 82c may each have a mechanism for pumping the liquids J to L from their containers, for example.

The concentration sensor 83 monitors the concentration of the electrolyte D in the electrolyte D mixing tank 80 and transmits the result to the control circuit 14. Based on the result of the concentration monitoring, the control circuit 14 controls the supply control unit 81 to adjust the concentration of the electrolyte D. The concentration sensor 83 may also measure the resistance value of the electrolyte D.

The control circuit 14 controls the entire anodizing apparatus 1. More specifically, the control circuit 14 controls the anodizing processing section 10, the electrolyte A supply unit 11, the electrolyte B supply unit 12, the electrolyte C supply unit 61, the electrolyte D supply unit 62, and the current supply unit 13.

7.1.2 Detailed Configuration of Anodizing Unit Next, an example of the detailed configuration of the anodizing unit 10 will be described with reference to Fig. 33. Fig. 33 is a cross-sectional view of the anodizing unit 10 in a state in which electrolytic solutions A to D are being supplied. The example of Fig. 33 shows a case in which the anodizing apparatus 1 has a "split electrode, multiple power sources, and split treatment tank" configuration, as in the first embodiment.

As shown in FIG. 33, the anodization treatment unit 10 includes treatment tanks 101, 103, 111, and 112, a bat 102, upper electrodes 104 and 106, an insulator 105, a lower electrode 107, and a holding unit 108. The configurations of the treatment tanks 101 and 103, the bat 102, upper electrodes 104 and 106, an insulator 105, and the lower electrode 107 are the same as those in FIG. 2 of the first embodiment. As in the first embodiment, a current source 40 is connected to the upper electrode 104. A current source 41 is connected to the upper electrode 106.

In this example, the upper end of the processing tank 111 is located on the lower surface of the upper electrode 104. The area surrounded by the lower surface of the upper electrode 104, the upper surface of the semiconductor substrate 1000, the side of the holding portion 108, and the side of the processing tank 112 corresponds to the processing tank 111. In other words, the processing tank 111 is provided between the upper electrode 104 and the processing tank 101.

The treatment tank 112 has, for example, a cylindrical shape. The treatment tank 112 is arranged, for example, concentrically with the treatment tank 111. The inner diameter of the treatment tank 112 is smaller than that of the treatment tank 111. For example, the inner diameter of the treatment tank 112 is approximately the same as that of the upper electrode 106. The treatment tank 112 corresponds to the formation of the porous layer 1100. The upper end of the treatment tank 112 contacts the lower surface of the upper electrode 106. The lower end of the treatment tank 112 is located near the upper surface of the semiconductor substrate 1000 and does not contact the upper surface of the semiconductor substrate 1000. The area surrounded by the lower surface of the upper electrode 106, the upper surface of the semiconductor substrate 1000, and the side surface of the treatment tank 112 corresponds to the treatment tank 112. In other words, the treatment tank 112 is provided between the upper electrode 106 and the treatment tank 103. A gap GP3 is provided between the lower end of the treatment tank 112 and the semiconductor substrate 1000. The side of the treatment tank 112 is made of, for example, an insulating material that is resistant to the electrolytes C and D. The treatment tank 112 may be made of the same material as the holding unit 108. Pipes 65 and 66 are connected to the treatment tank 103. Pipe 65 is a liquid supply line to the treatment tank 112. Pipe 66 is a liquid discharge line from the treatment tank 112. In this embodiment, pipe 65 is connected to a liquid supply line of the electrolyte C mixing tank 70. Pipe 66 is connected to a liquid recovery line of the electrolyte C mixing tank 70. Pipes 65 and 66 may be provided in multiple numbers. Furthermore, a waste liquid discharge pipe used when discharging the liquid in the treatment tank 112 as waste liquid may be connected to the treatment tank 112.

In this embodiment, the liquid pressure of electrolytes A and B is set higher than the liquid pressure of electrolytes C and D (liquid pressure of electrolyte A+B > liquid pressure of electrolyte C+D). Therefore, during anodization, the liquid pressure of electrolytes A and B presses the upper surface of the semiconductor substrate 1000 against the fixing portion 113.

The liquid pressure of electrolyte C is set higher than the liquid pressure of electrolyte D (liquid pressure of electrolyte C > liquid pressure of electrolyte D). As a result, during anodization, electrolyte C flows from treatment tank 112 toward treatment tank 111 through gap GP3. For example, when electrolytes A to D are supplied, the liquid pressures of electrolytes A to D may be in the following relationship: electrolyte A > electrolyte B > electrolyte C > electrolyte D.

7.2 Second Example Next, a second example will be described. In the second example, the configuration of the anodizing unit 10, which is different from that of the first example, will be described with reference to FIG. 34. FIG. 34 is a cross-sectional view of the anodizing unit 10 in a state in which electrolytic solutions A to D are being supplied. The example of FIG. 34 shows a case in which the anodizing apparatus 1 has a "same electrode, single power source, divided treatment tank" configuration, similar to the first example of the second embodiment.

The overall configuration of the anodizing apparatus 1 in this example is similar to that of the first example of the seventh embodiment shown in FIG. 32.

As shown in FIG. 34, the anodizing treatment unit 10 includes treatment tanks 101, 103, 111, and 112, a vat 102, an upper electrode 104, a lower electrode 107, and a holding unit 108.

The treatment tanks 101 and 103, the vat 102, the upper electrode 104, and the lower electrode 107 are the same as those in the first example of the second embodiment shown in FIG. 8. As in the first example of the second embodiment, a current is supplied to the upper electrode 104 from the current supply unit 13 (current source 40).

In this example, for example, the inner diameter of the treatment tank 111 is approximately the same as the inner diameter of the treatment tank 103. In other words, the treatment tank 111 is provided between the treatment tank 101 and the region of the upper electrode 104 that faces the treatment tank 101. The treatment tank 112 is provided between the treatment tank 103 and the region of the upper electrode 104 that faces the treatment tank 103.

7.3 Third Example Next, a third example will be described. In the third example, the configuration of the anodizing apparatus 1, which is different from the first and second examples, will be described with reference to Figs. 35 and 36. Fig. 35 is a block diagram of the anodizing apparatus. Fig. 36 is a cross-sectional view of the anodizing processing section 10 in a state in which electrolytic solutions A, C, and D are being supplied. The example of Fig. 36 shows a case in which the anodizing apparatus 1 has a "split electrode, single power source, and same processing tank" configuration, similar to the second example of the second embodiment.

As shown in FIG. 35, the anodizing apparatus 1 of this example has a configuration in which the electrolyte B supply unit 12 and the pipes 16 and 17 are eliminated from the configuration of the first example of the seventh embodiment (FIG. 32). The electrolyte A mixing tank 20 of the electrolyte A supply unit 11 is connected to the treatment tank 101 via the pipe 15.

As shown in FIG. 36, the anodization treatment unit 10 includes treatment tanks 101, 111, and 112, a bath 102, upper electrodes 104 and 106, an insulator 105, a lower electrode 107, and a holding unit 108.

The treatment tank 101, the vat 102, the upper electrodes 104 and 106, the insulator 105, and the lower electrode 107 are the same as those in FIG. 11 of the second example of the second embodiment. As in the second example of the second embodiment, in this example, the upper electrode 104 is connected to the current source 40 via the switch SW1. Also, the upper electrode 106 is connected to the current source 40 via the switch SW2.

In this example, the upper end of the treatment tank 111 is located on the lower surface of the upper electrode 104. The area surrounded by the lower surface of the upper electrode 104, the upper surface of the semiconductor substrate 1000, the side of the holding portion 108, and the side of the treatment tank 112 corresponds to the treatment tank 111. The upper end of the treatment tank 112 is located on the lower surface of the upper electrode 106. The area surrounded by the lower surface of the upper electrode 106, the upper surface of the semiconductor substrate 1000, and the side of the treatment tank 112 corresponds to the treatment tank 112. In other words, the treatment tank 111 is provided between the upper electrode 104 and the area of the treatment tank 101 facing the upper electrode 104. The treatment tank 112 is provided between the upper electrode 106 and the area of the treatment tank 101 facing the upper electrode 106.

7.4 Fourth Example Next, a fourth example will be described. In the fourth example, the configuration of the anodizing unit 10, which is different from that of the third example, will be described with reference to FIG. 37. FIG. 37 is a cross-sectional view of the anodizing unit 10 in a state in which electrolytic solutions A, C, and D are being supplied. The example of FIG. 37 shows a case in which the anodizing apparatus 1 has a "split electrode, multiple power sources, and the same treatment tank" configuration, similar to the third example of the second embodiment.

The overall configuration of the anodizing apparatus 1 in this example is similar to that of the third example of the seventh embodiment shown in FIG. 35.

As shown in FIG. 37, the anodization processing unit 10 includes processing tanks 101, 111, and 112, a bath 102, upper electrodes 104 and 106, an insulator 105, a lower electrode 107, and a holding unit 108.

The treatment tank 101, the vat 102, the upper electrodes 104 and 106, the insulator 105, and the lower electrode 107 are the same as those in the third example of the second embodiment shown in FIG. 13. As in the third example of the second embodiment, the upper electrode 104 is connected to a current source 40. The upper electrode 106 is connected to a current source 41.

The configuration of the treatment tanks 111 and 112 is the same as that of the third example of the seventh embodiment shown in Figure 36.

7.5 Effects of this embodiment With the configuration of this embodiment, the same effects as in the sixth embodiment can be obtained.

Furthermore, with the configuration according to this embodiment, between the upper electrode and the semiconductor substrate, electrolytes C and D with different resistance values can be supplied to the center and outer periphery of the upper surface of the semiconductor substrate. Furthermore, in the first, third, and fourth examples, electrolytes C and D can be supplied according to the amount of current supplied to the two upper electrodes 106 and 104, respectively. This improves the controllability of the formation of the porous layers 1100 and 1200 in the anodization process. Furthermore, the range of voltage control of the upper electrode can be made wider. Furthermore, power consumption can be reduced by adjusting the resistance values of electrolytes C and D.

8. Eighth embodiment Next, an eighth embodiment will be described. In the eighth embodiment, four examples of the configurations of the electrolytic solution C supply unit 61 and the electrolytic solution D supply unit 62 that are different from the first example of the seventh embodiment will be described. The following description will focus on the differences from the first example of the seventh embodiment.

8.1 First Example First, a first example of the anodizing apparatus 1 will be described with reference to Fig. 38. Fig. 38 is a block diagram of the anodizing apparatus 1. In the first example, unlike the first embodiment, a case will be described in which the electrolytic solution C supply unit 61 and the electrolytic solution D supply unit 62 do not have a circulation mechanism.

As shown in FIG. 38, the anodizing apparatus 1 of this example includes an anodizing processing section 10, an electrolyte A supply unit 11, an electrolyte B supply unit 12, an electrolyte C supply unit 61, an electrolyte D supply unit 62, a current supply unit 13, a control circuit 14, and concentration sensors 91 and 92.

The anodizing unit 10, electrolyte A supply unit 11, electrolyte B supply unit 12, current supply unit 13, and control circuit 14 are the same as those in the first example of the seventh embodiment shown in FIG. 32.

The electrolyte C supply unit 61 does not have a circulation mechanism and supplies unused electrolyte C to the anodization processing unit 10. That is, the electrolyte C supply unit 61 mixes three liquids G to I in the electrolyte C mixing tank 70 to produce electrolyte C.

Like the electrolyte C supply unit 61, the electrolyte D supply unit 62 does not have a circulation mechanism and supplies unused electrolyte D to the anodization processing unit 10. That is, the electrolyte D supply unit 62 mixes three liquids J to L in the electrolyte D mixing tank 80 to produce electrolyte D.

The pipe 64 is not connected to the electrolyte D mixing tank 80, and the liquid used in the treatment tank 111 is discharged as waste liquid.

The pipe 66 is not connected to the electrolyte C mixing tank 70, and the liquid used in the treatment tank 112 is discharged as waste liquid.

The concentration sensor 91 monitors the concentration of the wastewater in the pipe 66 and transmits the result to the control circuit 14. The concentration sensor 92 monitors the concentration of the wastewater in the pipe 64 and transmits the result to the control circuit 14. For example, in the anodizing device 1 of this example, the supply of new electrolytes C and D and the wastewater treatment are repeated for each anodizing treatment. However, if the monitoring result of the concentration sensor 91 determines that the electrolyte C in the treatment tank 112 can be reused in the next anodizing treatment, the anodizing device 1 can reuse all or a part of the electrolyte C in the treatment tank 112. Similarly, if the monitoring result of the concentration sensor 92 determines that the electrolyte D in the treatment tank 111 can be reused in the next anodizing treatment, the anodizing device 1 can reuse all or a part of the electrolyte D in the treatment tank 111. When a part of the electrolyte D is reused, the shortage of electrolytes C and D is supplied from the electrolyte C supply unit 61 and the electrolyte D supply unit 62, respectively.

8.2 Second Example Next, a second example of the anodizing apparatus 1 will be described with reference to Fig. 39. Fig. 39 is a block diagram of the anodizing apparatus 1. In the second example, a case will be described in which the electrolytic solution C supply unit 61 and the electrolytic solution D supply unit 62 circulate the wastewater from the treatment tank 111.

As shown in FIG. 39, the anodizing device 1 of this example includes an anodizing processing section 10, an electrolyte A supply unit 11, an electrolyte B supply unit 12, an electrolyte C supply unit 61, an electrolyte D supply unit 62, a current supply unit 13, and a control circuit 14.

The anodizing unit 10, electrolyte A supply unit 11, electrolyte B supply unit 12, current supply unit 13, and control circuit 14 are the same as those in the first example of the seventh embodiment shown in FIG. 32.

The electrolyte C supply unit 61 is the same as that shown in FIG. 32 of the first example of the seventh embodiment. In this example, the electrolyte C supply unit 61 collects liquid from the treatment tank 111 via piping 64. The electrolyte C supply unit 61 can mix the liquid (a mixture of electrolyte C and electrolyte D) collected from the treatment tank 111 via piping 64 with three liquids G to I to generate electrolyte C and adjust its concentration. Note that in this example, piping 66 is omitted, but piping 66 may be discarded or may be used as a line for discharging waste liquid from the treatment tank 112.

The electrolyte D supply unit 62 is the same as that shown in FIG. 32 of the first example of the seventh embodiment. The electrolyte D supply unit 62, like the electrolyte C supply unit 61, collects liquid from the treatment tank 111 via the pipe 64.

8.3 Third Example Next, a third example of the anodizing apparatus 1 will be described with reference to Fig. 40. Fig. 40 is a block diagram of the anodizing apparatus 1. In the third example, a case will be described in which the electrolytic solution C supply unit 61 does not have a circulation mechanism, and the electrolytic solution D supply unit 62 has a circulation mechanism.

As shown in FIG. 40, the anodizing apparatus 1 of this example includes an anodizing processing section 10, an electrolyte A supply unit 11, an electrolyte B supply unit 12, an electrolyte C supply unit 61, an electrolyte D supply unit 62, a current supply unit 13, a control circuit 14, and a concentration sensor 91.

The anodizing unit 10, electrolyte A supply unit 11, electrolyte B supply unit 12, electrolyte D supply unit 62, current supply unit 13, and control circuit 14 are the same as those in the first example of the seventh embodiment shown in FIG. 32.

The electrolyte C supply unit 61 and the concentration sensor 91 are the same as those in the first example of the eighth embodiment shown in FIG. 38.

8.4 Fourth Example Next, a fourth example of the anodizing apparatus 1 will be described with reference to Fig. 41. Fig. 41 is a block diagram of the anodizing apparatus 1. In the fourth example, a case will be described in which the electrolytic solution C supplying unit 61 has a circulation mechanism and the electrolytic solution D supplying unit 62 does not have a circulation mechanism.

As shown in FIG. 41, the anodizing device 1 of this example includes an anodizing processing section 10, an electrolyte A supply unit 11, an electrolyte B supply unit 12, an electrolyte C supply unit 61, an electrolyte D supply unit 62, a current supply unit 13, and a control circuit 14.

The anodizing unit 10, electrolyte A supply unit 11, electrolyte B supply unit 12, current supply unit 13, and control circuit 14 are the same as those in the first example of the seventh embodiment shown in FIG. 32.

The electrolyte C supply unit 61 is the same as that shown in FIG. 39 of the second example of the eighth embodiment. In this example, the electrolyte C supply unit 61 recovers liquid from the treatment tank 111 via the pipe 64. Note that, in this example, the electrolyte C supply unit 61 recovers liquid (a mixture of electrolyte C and electrolyte D) from the treatment tank 111 via the pipe 64, but the electrolyte C supply unit 61 may recover liquid (electrolyte C) from the treatment tank 112 via the pipe 66. In this case, for example, the pipe 64 connected to the treatment tank 111 is used as a waste liquid discharge line for the treatment tank 111.

The electrolyte D supply unit 62 is the same as that shown in FIG. 38 of the first example of the eighth embodiment. When the electrolyte C supply unit 61 recovers the liquid (electrolyte C) from the treatment tank 112 through the piping 66, that is, when the piping 66 is used as a waste liquid discharge line, the anodizing device 1 may have the concentration sensor 92 described in the first example of the sixth embodiment. When it is determined from the monitoring result of the concentration sensor 92 that the electrolyte D in the treatment tank 111 is reusable in the next anodizing process, the anodizing device 1 can reuse all or a part of the electrolyte D in the treatment tank 111.

8.5 Effects of this embodiment The configuration of this embodiment can be applied to the seventh embodiment.

9. Ninth embodiment Next, a ninth embodiment will be described. In the ninth embodiment, two examples of the configuration of the holding portion 108 that differs from the fifth and seventh embodiments will be described. The following description will focus on the differences from the fifth and seventh embodiments.

9.1 First Example First, the first example will be described. In the first example, a case where the holding part 108 has two fixed parts 113a and 113b arranged above and below will be described with reference to Figs. 42 to 45. Fig. 42 is a cross-sectional view of the anodizing unit 10 in a state in which the electrolytic solutions A to C are being supplied. Fig. 43 is a top view of the fixed part 113a. Figs. 44 and 45 are enlarged views of the region RA in Fig. 42. Fig. 44 shows the positions of the fixed parts 113a and 113b when the semiconductor substrate 1000 is set in the anodizing apparatus 1. Fig. 45 shows the positions of the fixed parts 113a and 113b during the anodizing process.

As shown in FIG. 42, the anodizing treatment unit 10 includes treatment tanks 101, 103, and 111, a vat 102, upper electrodes 104 and 106, an insulator 105, a lower electrode 107, and a holding unit 108. The treatment tanks 101, 103, and 111, the vat 102, upper electrodes 104 and 106, an insulator 105, and a lower electrode 107 are the same as those in the first example of the seventh embodiment. The configuration of the anodizing treatment unit 10 may be any of the configurations described in the fifth and seventh embodiments.

The holding portion 108 includes a plurality of fixing portions 113a and 113b. The cross-sectional shape of the fixing portions 113a and 113b may be, for example, triangular. The shape of the fixing portions 113a and 113b is arbitrary. It is preferable that the cross-sectional shape of the fixing portions 113a and 113b is capable of holding the semiconductor substrate 1000 and has a smaller contact surface with the semiconductor substrate 1000.

Fixed portion 113a and fixed portion 113b are arranged at different height positions on the side surface of holding portion 108. For example, fixed portion 113a is arranged closer to the upper end of holding portion 108 (closer to upper electrode 104) than fixed portion 113b. Fixed portions 113a and 113b are movable between a state in which they protrude from the inner surface of holding portion 108 (hereinafter referred to as the "protruding state") and a state in which they are recessed into holding portion 108 (hereinafter referred to as the "retracted state").

As shown in FIG. 43, for example, the three fixing portions 113a are arranged at positions rotated 120° with respect to the center of the holding portion 108. Note that the example in FIG. 43 shows a case where the fixing portions 113a are in a protruding state. The fixing portions 113a have, for example, a triangular shape when viewed from above. Therefore, the fixing portions 113a may have, for example, a cone or a pyramid shape. Note that the number of fixing portions 113a is arbitrary. It is sufficient that at least three or more fixing portions 113a are arranged so that the semiconductor substrate 1000 can be fixed during anodization.

The fixed portion 113b is similar to the fixed portion 113a. Note that the shape, number, and arrangement of the fixed portion 113b may be different from those of the fixed portion 113a.

Next, the operation of the fixed portions 113a and 113b will be described.
44, for example, when the semiconductor substrate 1000 is set inside the holding portion 108, the fixing portion 113a is retracted and the fixing portion 113b is protruding. As a result, when the semiconductor substrate 1000 is set from above, the fixing portion 113b holds the lower surface of the semiconductor substrate 1000, preventing the semiconductor substrate 1000 from falling.

As shown in FIG. 45, for example, during anodization, the fixing portion 113a is in a protruding state and the fixing portion 113b is in a retracted state. As a result, the semiconductor substrate 1000 is pressed against the fixing portion 113a from below, and its position is fixed.

9.2 Second Example Next, a second example will be described. In the second example, an elastic material is used for the holding portion 108, which will be described with reference to Fig. 46. Fig. 46 is a conceptual diagram showing the arrangement of the holding portion 108 and the semiconductor substrate 1000.

As shown in FIG. 46, when an elastic material is used for the holding portion 108, when the tip of the semiconductor substrate 1000 is pressed against the holding portion 108, the sealing performance between the holding portion 108 and the semiconductor substrate 1000 is improved. Note that the holding portion 108 may be in contact with the entire outer periphery of the semiconductor substrate 1000, or may be in contact with only a part of the outer periphery.

9.3 Effects of this Embodiment The configuration of this embodiment can be applied to the fifth to eighth embodiments.

The first and second examples of this embodiment may be combined.

10. Modified Examples The anodizing apparatus according to the above embodiment includes a first treatment tank (101) capable of performing anodizing treatment on a substrate, a second treatment tank (103) provided inside the first treatment tank and capable of performing anodizing treatment on a substrate, a first electrolytic solution supply unit (12) capable of supplying a first electrolytic solution to the first treatment tank, a second electrolytic solution supply unit (11) capable of supplying a second electrolytic solution to the second treatment tank, a holding section (108) capable of holding a substrate, a first electrode (104) provided above the first treatment tank or the second treatment tank, and a second electrode (107) provided below the first treatment tank and the second treatment tank.

By applying the above embodiment, multiple porous layers with different film properties can be formed on the substrate surface.

Note that the embodiment is not limited to the above-described form, and various modifications are possible.

For example, in the above embodiment, an anodization apparatus capable of forming porous layers of two different film qualities at the center and outer periphery of the semiconductor substrate surface has been described, but an anodization apparatus capable of forming porous layers of three or more different film qualities may also be used. More specifically, in the anodization apparatus 1, three or more upper electrodes may be provided, for example, in a concentric pattern, and three or more treatment tanks may be provided, for example, in a concentric pattern.

In addition, "connected" in the above embodiment also includes a state in which something else is interposed and indirectly connected.

In addition, "substantially the same" in the above embodiment includes an error in performing the anodizing process that does not affect the formation of the porous layer.

Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the gist of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are included in the scope of the invention and its equivalents described in the claims.

1...Anodizing apparatus 10...Anodizing processing section 11...Electrolyte A supply unit 12...Electrolyte B supply unit 13...Current supply section 14...Control circuit 15-19, 63-66...Pipes 20...Electrolyte A mixing tank 21, 31, 71, 81...Supply control section 22a-22c, 32a-32c, 72a-72c, 82a-82c...Liquid supply section 23, 33, 50, 73, 83, 91, 92...Concentration sensor 30...Electrolyte B mixing tank 40, 41...Current source 61...Electrolyte C supply unit 62...Electrolyte D supply unit 70...Electrolyte C mixing tank 80...Electrolyte D mixing tank 101, 103, 111, 112...Treatment tank 102...Bath 104, 106...Upper electrode 105...Insulator 107...Lower electrode 108: Holding portion 113, 113a, 113b: Fixed portion 1000, 1000a, 1000b: Semiconductor substrate 1100, 1200: Porous layer SW1, SW2: Switch

Claims (16)

a cylindrical first treatment tank capable of performing anodizing on a substrate;
a second treatment tank capable of performing anodizing treatment on the substrate, having a cylindrical shape with an inner diameter smaller than that of the first treatment tank, and disposed concentrically inside the first treatment tank ;
a first electrolytic solution supply unit capable of supplying a first electrolytic solution to the first treatment tank;
a second electrolytic solution supply unit capable of supplying a second electrolytic solution to the second treatment tank ;
a first electrode provided above at least the first treatment tank ;
a second electrode provided below the first treatment tank and the second treatment tank and in contact with a lower end of the first treatment tank and the second treatment tank ;
a holding section between the first electrode and the first treatment tank and between the first electrode and the second treatment tank, the holding section being capable of holding the substrate such that a first surface of the substrate faces the first electrode, a second surface of the substrate opposed to the first surface faces the second electrode, and the second surface is in contact with the first electrolytic solution supplied to the first treatment tank and the second electrolytic solution supplied to the second treatment tank;
Equipped with
Anodizing equipment. The piezoelectric element further includes a third electrode disposed concentrically around the first electrode on the inner side of the first electrode,
the first electrode faces the first treatment tank, and the third electrode faces the second treatment tank;
The anodizing apparatus according to claim 1 . The first electrolytic solution supply unit is capable of generating the first electrolytic solution using at least a first liquid,
The first electrolytic solution supply unit is
A first mixing tank capable of storing the first electrolytic solution;
a first concentration sensor capable of monitoring a concentration of the first electrolytic solution in the first mixing tank;
a first supply control unit capable of controlling the supply of the first liquid to the first mixing tank based on a result of the first concentration sensor.
The anodizing apparatus according to claim 1 or 2. The first electrolytic solution supply unit is capable of generating the first electrolytic solution by further using a second liquid recovered from the first treatment tank.
The anodizing apparatus according to claim 3 . The second electrolytic solution supply unit is capable of generating the second electrolytic solution using at least a third liquid,
The second electrolytic solution supply unit is
A second mixing tank capable of storing the second electrolytic solution;
a second concentration sensor capable of monitoring a concentration of the second electrolytic solution in the second mixing tank;
and a second supply control unit capable of controlling the supply of the third liquid to the second mixing tank based on a result of the second concentration sensor.
The anodizing apparatus according to claim 1 . The second electrolytic solution supply unit is capable of generating the second electrolytic solution by further using a fourth liquid recovered from the first treatment tank.
The anodizing apparatus according to claim 5 . The second electrolytic solution supply unit is capable of generating the second electrolytic solution by further using a fifth liquid recovered from the second treatment tank.
The anodizing apparatus according to claim 5 . a first current source capable of supplying a first current to the first electrode;
a second current source capable of supplying a second current different from the first current to the third electrode.
The anodizing apparatus according to claim 2 . A third current source;
a first switch capable of electrically connecting the third current source and the first electrode;
a second switch capable of electrically connecting the third current source and the third electrode.
The anodizing apparatus according to claim 2 . a third processing tank provided between the substrate held by the holder and the first electrode , the third processing tank having a cylindrical shape and an upper end in contact with the first electrode ;
and a third electrolytic solution supply unit capable of supplying a third electrolytic solution to the third treatment tank ,
the first surface of the substrate held by the holding unit is in contact with the third electrolytic solution supplied to the third treatment tank;
The anodizing apparatus according to claim 1 . a third treatment tank provided between the substrate held by the holder and the first electrode, facing the first treatment tank, having a cylindrical shape, and an upper end of the third treatment tank being in contact with the first electrode;
a fourth treatment tank provided between the substrate held by the holder and the third electrode , facing the second treatment tank, having a cylindrical shape with an inner diameter smaller than that of the third treatment tank, and arranged concentrically with the third treatment tank, the upper end of which is in contact with the third electrode ;
a third electrolytic solution supply unit capable of supplying a third electrolytic solution to the third treatment tank ;
and a fourth electrolytic solution supply unit capable of supplying a fourth electrolytic solution to the fourth treatment tank ,
the first surface of the substrate held by the holding unit is in contact with the third electrolytic solution supplied to the third treatment tank and the fourth electrolytic solution supplied to the fourth treatment tank;
The anodizing apparatus according to claim 2 . The third electrolytic solution supply unit is capable of generating the third electrolytic solution using at least a sixth liquid,
The third electrolytic solution supply unit is
a third mixing tank capable of storing the third electrolytic solution;
a third concentration sensor capable of monitoring a concentration of the third electrolytic solution in the third mixing tank;
and a third supply control unit capable of controlling the supply of the sixth liquid to the third mixing tank based on a result of the third concentration sensor.
The anodizing apparatus according to claim 10 or 11 . The third electrolytic solution supply unit is capable of generating the third electrolytic solution by further using a seventh liquid recovered from the third treatment tank.
The anodizing apparatus according to claim 12 . a cylindrical first treatment tank capable of performing anodizing on a substrate;
a first electrolytic solution supply unit capable of supplying a first electrolytic solution to the first treatment tank ;
a first electrode provided above the first treatment tank and supplied with a first current ;
a second electrode disposed concentrically around the first electrode and inside the first electrode, the second electrode being supplied with a second current different from the first current ;
a third electrode facing the first electrode and the second electrode , provided below the first treatment tank , and in contact with a lower end of the first treatment tank ;
a second treatment tank provided between the first treatment tank and the first electrode, the second treatment tank having a cylindrical shape and an upper end contacting the first electrode;
a third treatment tank provided between the first treatment tank and the second electrode, having a cylindrical shape with an inner diameter smaller than that of the second treatment tank, and arranged concentrically with the second treatment tank inside the second treatment tank, with an upper end of the third treatment tank being in contact with the second electrode;
a second electrolytic solution supply unit capable of supplying a second electrolytic solution to the second treatment tank;
a third electrolytic solution supply unit capable of supplying a third electrolytic solution to the third treatment tank;
a cylindrical holder between the second and third treatment tanks and the first treatment tank, the holder being capable of holding the substrate such that a first surface of the substrate faces the first electrode and the second electrode, a second surface of the substrate opposed to the first surface faces the third electrode, the first surface comes into contact with the second electrolytic solution supplied to the second treatment tank and the third electrolytic solution supplied to the third treatment tank, and the second surface comes into contact with the first electrolytic solution supplied to the first treatment tank;
Equipped with
Anodizing equipment. a first current source capable of supplying the first current to the first electrode;
and a second current source capable of supplying the second current to the second electrode.
The anodizing apparatus according to claim 14. A third current source;
a first switch capable of electrically connecting the third current source and the first electrode;
a second switch capable of electrically connecting the third current source and the second electrode.
The anodizing apparatus according to claim 14.