JPS6059315B2 - Method of forming patterned aluminum layer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of forming a patterned aluminum layer on an insulating substrate, and is particularly applicable and suitable for forming a wiring layer of a semiconductor integrated circuit device. .

The wiring layer of a semiconductor integrated circuit device is usually made of an aluminum layer for various reasons. To form a wiring layer made of an aluminum layer for a semiconductor integrated circuit device, conventionally, an aluminum layer to be patterned is formed on a semiconductor substrate, and then a patterned photoresist mask is placed on the aluminum layer. It was common practice to form a patterned aluminum layer as a wiring layer by chemically etching the aluminum layer to be patterned using the above mask as a mask. . However, in the case of such a conventional method, in the step of chemically etching the aluminum layer to be patterned using the patterned mask layer as a mask, the patterned aluminum layer is etched from the side. There is no choice but to obtain a so-called side-etched material. Therefore, the patterned aluminum layer is formed to have a pattern that is one size smaller than the pattern of the mask layer by an amount that is side-etched. Incidentally, it is desirable that the patterned aluminum layer be obtained in the same pattern as the pattern of the mask layer.

The reason is that by simply forming a mask layer in the same pattern as the patterned aluminum layer to be formed, the patterned aluminum layer can be formed with the desired pattern. It's because you can do it. However, even if the patterned aluminum layer is formed with a pattern that is one size smaller than the pattern of the mask layer by the amount side-etched, the amount side-etched will be smaller in the chemical etching process described above. , if expected, the pattern in the mask layer, allowing for the amount to be side-etched, saw around the desired pattern of the patterned aluminum layer to a larger pattern;
By forming the aluminum layer in advance, the patterned aluminum layer can be formed to have a desired pattern. However, in the case of the above-mentioned conventional method, in the above-mentioned chemical etching step,
It was extremely difficult to predict the amount of side etching mentioned above.

For this reason, the conventional method described above has drawbacks such as the fact that it is extremely difficult to form a patterned aluminum layer with a desired pattern in a fine and highly accurate manner. Ta. The invention therefore seeks to propose a new method for forming patterned aluminum layers that does not suffer from the drawbacks mentioned above. The inventor first
As shown in FIG. On the layer 2, as shown in FIG. 1B, an aluminum layer 4 to be patterned is formed, as is known per se, for example by vapor deposition, and then on the aluminum layer 4 to be patterned. As shown in FIG. 1C, a patterned mask layer 5 made of, for example, photoresist is formed on the aluminum layer 4 on the insulating substrate 3, and a photomask is applied to the photoresist layer. The aluminum layer 4 to be patterned is formed on the insulating substrate 3, and the aluminum layer 4 to be patterned is formed on the insulating substrate 3. A substrate body 6 on which a patterned mask layer 5 was formed was obtained.

Then, as shown in FIG.
The aluminum layer 4 is immersed in a tank 12 containing an electrolytic solution 11 consisting of an aqueous solution mainly containing H3PO4) and nitric acid (HNO3C) as solutes, so that the aluminum layer 4 extends substantially vertically, and An electrode 13 made of, for example, platinum is immersed in the bath 12 so as to face the aluminum layer 4 of the substrate 6, and the aluminum layer 4 to be patterned on the substrate 6 is covered with the mask layer 5. The electrode 13 is connected to the positive electrode side of the DC power source 14 in the unmasked region, and the electrode 13 is connected to the negative electrode side of the DC power source 14, and the mask layer 5 is used as a mask against the aluminum layer 4, and the phosphoric acid Electrolytic etching was performed using an electrolytic solution consisting of an aqueous solution containing nitric acid as the main solute.

However, in this case, the electrolytic solution 11, which is an aqueous solution containing phosphoric acid and nitric acid as solutes, is mixed with a phosphoric acid solution with a concentration of 50 to 85%.
A nitric acid solution with a concentration of ~60% is used as a solute.
4 parts by volume of an aqueous solution.

In that case, the area of the aluminum layer 4 not masked by the mask layer 5 acts as an anode, and
On the anode side, a chemical reaction expressed by occurs, and in the electrolyte 11, a chemical reaction mainly occurs, and furthermore, the electrode 13 acts as a cathode, and on the cathode side, a chemical reaction expressed as 3A, the area of the aluminum layer 4 that is not masked by the mask layer 5 is
from the unetched state shown in FIG. 3B, through the surface-etched state shown generally in FIG. It has now been confirmed that an etched and patterned aluminum layer 7 is formed under the mask layer 5.

However, in this case, the electrode 13 was made of platinum. Further, the present inventor has discovered that even when the above-mentioned electrolytic etching gate is performed by adding acetic acid (CH3COOH) as a solute to the electrolytic solution 11 which is an aqueous solution mainly containing phosphoric acid and nitric acid as solutes, In the same manner as above, it was confirmed that a patterned aluminum layer 7 was formed under the mask layer 5.

However, in this case, acetic acid is added as a solute to the electrolytic solution 11 which is an aqueous solution containing phosphoric acid (consisting of a phosphoric acid solution with a concentration of 50 to 85%) and nitric acid (consisting of a nitric acid solution with a concentration of 30 to 60%) as solutes. , an acetic acid solution with a concentration of 70 to 100%, and the acetic acid solution is 1 to 4 parts by volume per 15 to 2 parts by volume of the phosphoric acid solution and 1 to 4 parts by volume of the nitric acid solution. did.

Furthermore, the present inventor carried out the above-mentioned electrolytic etching by using the DC power supply 14 connected between the aluminum layer 4 to be patterned and the electrode 13 as a DC constant current source, and using the mask layer of the aluminum layer 4 as a DC constant current source. The voltage V (volts) between the area not masked by 5 and the electrode 13 is
The test was carried out while being measured using a voltmeter 15.

In such a case, the relationship between the voltage ■ and the time t (minutes) is as shown in FIG.
It was obtained that the voltage V increases slightly with time t, but the voltage V suddenly increases from time Ta.

Furthermore, as a result of investigating the relationship of the voltage V with respect to the time t mentioned above and the state of etching of the region of the aluminum layer 4 that is not masked by the mask layer 5, the inventor found that the voltage V changes with time t. Time point T8 when it is rising slightly
Until then, the mask layer 5 of the aluminum layer 4
The areas not masked by the mask layer 5 are etched from the surface over time t, but once time t1 is reached, the areas of the aluminum layer 4 that are not masked by the mask layer 5 have been etched over their entire thickness. Figure 3C
It has now been confirmed that a patterned aluminum layer 7 is obtained, as generally shown in FIG.

Furthermore, the present inventor has proposed that the above-mentioned electrolytic etching,
The point in time when the voltage V mentioned above suddenly increases. The above-described patterned aluminum layer 7 is etched up to the point where the regions of the Ta or aluminum layer 4 not masked by the mask layer 5 are etched over their entire thickness.
When forming ., the patterned aluminum layer 7 is . It has been found that, in general, the side surfaces are obtained as side etched, as shown in FIG. 3C as being inside the side surfaces of the mask layer 5.

Further, the present inventor carried out the above-mentioned electrolytic etching by using the DC power supply 14 connected between the aluminum layer 4 to be patterned and the electrode 13 as a DC constant voltage source, and from the DC constant voltage source. The current 1 (MA) flowing through the aluminum layer 4 was measured using an ammeter 16.

In such a case, the relationship between current 1 and time t (minutes) is as shown in FIG. The current 1 was obtained as rapidly decreasing. Furthermore, as a result of investigating the relationship of the current 1 to the time t mentioned above and the state of etching in the area of the aluminum layer 4 that is not masked by the mask layer 5, the inventor found that the current 1 changes with the time t. Until the time t1'' when the aluminum layer 4 gradually decreases, the area of the aluminum layer 4 that is not masked by the mask layer 5 is etched from the surface with time t, but when time T8'' is reached, The area of the aluminum layer 4 not masked by the mask layer 5 is etched over its entire thickness, as shown in FIG. 3C.
It has now been confirmed that a patterned aluminum layer 7 is obtained, as generally shown in FIG. Furthermore, the present inventors carried out the above-mentioned electrolytic etching at a point Ta'' when the above-mentioned current 1 suddenly decreases, that is, when the region of the aluminum layer 4 that is not masked by the mask layer 5 reaches its full thickness. When etched to the point where it is etched to form the patterned aluminum layer 7 described above, the patterned aluminum layer 7 will generally have its sides exposed to the mask layer 5 in FIG. 3C. We have now confirmed that the material is side-etched, as indicated by the fact that it is on the inside of the side surface.

Further, the present inventor carried out the above-mentioned electrolytic etching by setting the temperature TCC of the electrolytic solution 11 at a constant temperature Te (° C.), and passing the electrolytic solution 11 from the DC power supply 14 through the aluminum layer and the electrode 13 in the substrate body 6. Therefore, the current density J (MA/
If the DC power source 14 is a DC low current source by changing Cli), the time T. If the DC power supply 14 is a DC constant voltage source, the current 1 described above is until the time t1'' when it suddenly decreases, that is, the area of the aluminum layer 4 that is not masked by the mask layer 5 is , until the entire thickness of the aluminum layer 7 is etched to form the above-described patterned aluminum layer 7, and then the amount by which the aluminum layer 7 is side etched, that is, the side etching amount Y (μm
) was measured.

In such a case, the relationship between the side etching amount Y and the current density J with the temperature T of the electrolytic solution as a parameter is as follows.
The result was obtained as shown in FIG.

However, in FIG. 6, the electrolyte 11 is an aqueous solution containing as solutes phosphoric acid consisting of 1 volume part of a 85% concentration phosphoric acid solution and nitric acid consisting of 1 volume part of a 65% concentration nitric acid solution. , and the measurement results were obtained when the temperature TeCC) of the electrolytic solution 11 was -33.0°C and the aluminum layer 4 had a thickness of 1 μm. Furthermore, even when the above-mentioned measurement was carried out by adding acetic acid, which is 1 volume part of a 96% acetic acid solution, to the electrolytic solution 11, similar measurement results were obtained as shown in FIG. . Therefore, from the measurement results shown in FIG. 6, when the temperature T of the electrolytic solution 11 is a constant temperature TeCC), if the current density J is increased, the side etching amount Y described above is
We have come to the conclusion that it becomes small.

Furthermore, if the current flowing through the electrolytic solution 11 is increased so that the current density J becomes large, the side etching amount Y
is obtained when the current density J is large, the electric field strength between the aluminum layer 4 and the electrode 13 is mainly related to the direction connecting the aluminum layer 4 and the electrode 13, This increases the etching speed in the thickness direction of the region of the aluminum layer 4 that is not masked by the mask layer 5.
We have also confirmed that this is because the ratio to the etching speed in the planar direction is large. Furthermore, it has been confirmed that when the current density J is kept constant, if the temperature T of the electrolytic solution 11 is lowered, the above-mentioned side etching amount Y becomes smaller. Furthermore, it has been confirmed that in order to obtain the same amount of side etching Y as described above, if the temperature T of the electrolytic solution 11 is increased, the current density J can be increased accordingly. Furthermore, from the measurement results shown in FIG. 6, the relationship between the current density J and the temperature T of the electrolytic solution 11 when the value of the side etching amount Y becomes zero can be obtained as shown in FIG. , and as described above, when the temperature T of the electrolytic solution 11 is constant, the side etching amount Y described above decreases as the current density J increases. If the temperature T is set to the temperature TeCC) and the current density J is set to a current density equal to or higher than the current density e(MA/ClL) given by
As shown in the figure, it has also been confirmed that the side etching amount Y mentioned above is approximately zero.

Furthermore, the relationship between the current density J and the temperature of the electrolytic solution 11 is obtained as shown in FIG.
), if the temperature T of the electrolytic solution 11 is lowered, the side etching amount Y mentioned above becomes smaller.
lf) and the temperature T of the electrolytic solution 11 is set to a temperature below the temperature TeCC) given by , the patterned aluminum layer 7 described above will be etched by the side etching amount as shown in FIG. It has also been confirmed that Y is formed as being substantially zero.

Therefore, the present inventor has come to propose the claimed invention as an invention according to the present invention.The method for forming a patterned aluminum layer according to the present invention has been clarified above. Ta.

According to the method according to the present invention, in the step of electrolytically etching the aluminum layer to be patterned using the patterned mask layer as a mask, the side of the patterned aluminum layer to be formed is As is clear from the above description in FIG. 6, the etching amount Y is determined by the temperature T of the electrolytic solution and the current density J.
You can make predictions. Therefore, in the step of forming a patterned mask layer on the aluminum layer to be patterned, the patterned mask is
By taking into account the expected amount of side etching Y, the patterned aluminum layer can be easily formed with the desired pattern finely and with high precision. have

In addition, in the electrolytic etching process described above, the electrolytic etching is performed by changing the temperature T of the electrolytic solution to a temperature Te (°C).
If the current density J is set to be equal to or higher than the current density Je(MA/Cli) given by equations (1a) to (1c) above, or the current density J is changed to the current density Je(
MA/Cw and the temperature T of the electrolyte was as described above (2a
) to (2c), the patterned aluminum layer is formed with a side etching amount Y of approximately zero.

For this reason, in the process of forming a patterned mask layer, the mask layer is formed in the same pattern as the intended pattern of the patterned aluminum layer to be formed, and also in the electrolytic etching process described above. When the temperature T of the electrolytic solution is the temperature Te, the current density J is given by the above equations (1a) to (1c).
When the current density is equal to or higher than e, or when the current density J is the current density Je, the temperature T of the electrolytic solution is set to the above (2a) to
(2c) Make the temperature higher than the temperature Te given by the equation.
Accordingly, a patterned aluminum layer having a desired pattern can be easily formed finely and with high precision.

Furthermore, the above-mentioned electrolytic etching can be performed using a current source! When performing electrolytic etching using a direct current constant current source, the end point of the electrolytic etching process is such that the voltage between the aluminum layer to be patterned as an anode and the cathode electrode relative to it is abrupt. The electrolytic etching described above must be carried out until the voltage between the aluminum layer to be patterned as an anode and the cathode electrode relative thereto suddenly increases. Accordingly, a patterned aluminum layer having a desired pattern 4 can be easily formed with good reproducibility, finely, and with high precision.

Furthermore, when electrolytic etching is performed using a DC constant current source as a DC power source, the voltage between the aluminum layer to be patterned as an anode and the cathode electrode relative to the aluminum layer described above increases suddenly. This can be easily detected by various voltage detectors, and
Depending on the output of the voltage detector, the DC constant current source connected between the aluminum layer as an anode and the corresponding cathode electrode can be turned off, or the DC constant current source and the aluminum layer as an anode or By a simple method such as cutting the line between the cathode and the cathode, the electrolytic etching described above can be carried out by rapidly increasing the voltage between the aluminum layer to be patterned as an anode and the cathode. It can be terminated immediately and easily when it reaches a certain size.

In addition, when the above-mentioned electrolytic etching is performed using a DC constant voltage source as a DC power source, the end point of the electrolytic etching in the electrolytic etching process is determined by the DC constant voltage source patterned as an anode. This corresponds to the point at which the current flowing through the aluminum layer to be patterned becomes suddenly smaller, so the electrolytic etching described above is carried out from a direct current constant voltage source through the aluminum layer to be patterned as an anode. The patterned aluminum layer is made to have the desired pattern with good reproducibility by repeating the process until the current suddenly decreases.
It has the characteristics of being able to be formed finely, with high precision, and easily.

Furthermore, when electrolytic etching is carried out using a DC constant voltage source as the DC power source, the point at which the current flowing from the DC constant voltage source through the aluminum layer to be patterned as an anode suddenly decreases. This can be easily detected by various current detectors, and the output of the current detector can be used to connect the aluminum layer as an anode to the cathode electrode. The electrolytic etching described above can be performed with a constant DC voltage by simple means such as turning off the constant DC voltage source in the It can be terminated immediately and easily at the point at which the current flowing from the voltage source through the aluminum layer to be patterned as anode drops off sharply.

Therefore, the above-mentioned features of the present invention can be reliably and easily exhibited. It is also formed by the method of forming a patterned aluminum layer according to the present invention. The patterned aluminum layer functions as a wiring layer. Therefore, the present invention solves this by
The present invention is characterized in that it is extremely suitable for application to forming wiring layers of semiconductor integrated circuit devices.

Next, an example of the present invention will be described.

Example 1 In the same manner as described above with reference to FIG. 1A, an insulating substrate 3 having an insulating layer 2 formed on the substrate 1 was prepared in advance.

However, in this case, the substrate 1 was made of silicon and had a surface area of about 40.0 d. Further, the insulating layer 2 was made of silicon oxide (SiO2). Thus, on the insulating layer 2 of the insulating substrate 3, an aluminum layer 4 to be patterned was formed in the same manner as described above with reference to FIG. 1B. however,
In this case, the aluminum layer 4 was formed by vapor deposition to have a thickness of 1 μm. Next, a patterned mask layer 5 was formed on the aluminum layer 4 in the same manner as described above in FIG. 1C.

However, in this case, the mask layer 5 can be made of a photoresist by forming a photoresist layer on the aluminum layer 4, exposing the photoresist layer to light using a photomask, and subsequently developing it. Formed as. In this way, an aluminum layer 4 to be patterned on an insulating substrate 3, similar to that described above in FIG. 1C.
A substrate body 6 was obtained in which a patterned mask layer 5 was formed on the aluminum layer 4.

Next, the substrate body 6 is heated to 85% as described above in FIG.
An aluminum layer 4 is placed in a tank 12 containing an electrolytic solution 11 made of an aqueous solution with phosphoric acid having a concentration of 1 volume part of a phosphoric acid solution and nitric acid having a concentration of 1 volume part of a 60% nitric acid solution as solutes. is immersed so that it extends substantially on a vertical plane, and
An electrode 13 made of platinum is immersed in the bath 12 so as to face the aluminum layer 4 of the substrate 6, and the aluminum layer 4 to be patterned on the substrate 6 is immersed.
is connected to the positive electrode side of a DC power source 14 consisting of a DC constant current source in a region not masked by the mask layer 5, and the electrode 13 is connected to the negative electrode side of the DC power source 14, so that the aluminum layer 4, electrolytic etching using the electrolytic solution 11, which is an aqueous solution containing phosphoric acid and nitric acid as solutes, is performed at a voltage V between the aluminum layer 4 and the electrode 13.
The patterned aluminum layer 7 was obtained until the point where the value suddenly increased.

In this case, the temperature of the electrolyte 11 is 33.0°C, the current passed through the electrolyte 11 is 240.0rr1A, and the current density passed through the aluminum layer 4 is 6.0 (=
240.0rr1A/40.0clt) MA/Clt.

In that case, the patterned aluminum layer 7 was formed with approximately zero side etching amount. Example 2 As in Example 1 of the present invention described above, an aluminum layer 4 to be patterned is formed on an insulating substrate 3, similar to that described above in FIG. A substrate body 6 was obtained, on which a patterned mask layer 5 was formed.

Next, the electrolytic solution 11 in the case of Example 1 of the present invention described above was mixed with phosphoric acid consisting of 1 part of phosphoric acid solution at a concentration of 85%,
The present invention as described above, except that the aqueous solution was changed to an aqueous solution in which the solutes were nitric acid consisting of 1 part by volume of a 60% concentration nitric acid solution and acetic acid consisting of 1 volume part of a 96% concentration acetic acid solution. The same electrolytic etching as in Example 1 of the present invention was performed in the same manner as in Example 1 of the present invention described above to obtain a patterned aluminum layer 7. In that case, as in the case of Example 1 of the present invention described above, the patterned aluminum layer 7'' was formed with a side etching amount of approximately zero.

Embodiment 3 DC power supply 14 in the case of Embodiment 1 of the present invention described above
is a DC constant voltage source, and the voltage is changed accordingly. The same process as in Example 1 of the present invention described above was carried out, except that the etching was carried out from a DC constant voltage source until the point where the current 1 flowing through the aluminum layer suddenly decreased. As a result, a patterned aluminum layer 7 was obtained.

In that case, the patterned aluminum layer 7 was formed so that the amount of side etching was approximately zero, as in the case of Example 1 of the present invention described above.

Example 4 DC power supply 14 in the case of Example 2 of the present invention described above
was used as a DC constant voltage source, and the electrolytic etching was carried out accordingly until the current 1 flowing through the aluminum layer suddenly decreased from the DC constant voltage source. A patterned aluminum layer 7 was obtained using the same steps as in Example 2 of the invention.

In this case, as in the case of Example 2 of the present invention described above, the patterned aluminum layer 7 was formed with a side etching amount of approximately zero.

[Brief explanation of the drawing]

1A, B and C illustrate the sequence of forming a patterned mask layer 5 on the aluminum layer to be patterned, serving to illustrate the method of forming a patterned aluminum layer according to the invention. It is a line sectional view in a process. FIG. 2 likewise illustrates the process of forming a patterned aluminum layer by electrolytic etching on the aluminum layer to be patterned, illustrating the method of forming a patterned aluminum layer according to the invention. It is a route map showing. FIG. 3 shows the formation of a patterned aluminum layer by electrolytic etching on the aluminum layer to be patterned, likewise illustrating the method of forming a patterned aluminum layer according to the invention. It is a line sectional view in a process. FIG. 4 likewise serves to explain the method of forming a patterned aluminum layer according to the invention by electrolytic etching of the aluminum layer to be patterned using a direct current power source consisting of a direct current constant current source. , the voltage V. between the aluminum layer as anode on the substrate body and the cathode electrode therewith over time t (minutes) in the process of forming a patterned aluminum layer.
This diagram shows the relationship between (bolts). Similarly, FIG.
To explain the method of forming a patterned aluminum layer according to the present invention, a patterned aluminum layer is formed by electrolytic etching of the aluminum layer to be patterned using a DC power supply consisting of a DC constant voltage source. FIG. 3 is a diagram showing the relationship of current 1 (MA) flowing from a DC constant voltage source through an aluminum layer as an anode in a substrate body with respect to time t (minutes) in a forming step. FIG. 6 also shows the formation of a patterned aluminum layer by electrolytic etching on the aluminum layer to be patterned, illustrating the method of forming a patterned aluminum layer according to the invention. In the process, the temperature of the electrolyte is used as a parameter,
FIG. 2 is a diagram showing the relationship between the side etching amount Y (μm) of a patterned aluminum layer formed according to the present invention and the current density J (MA/Clt). FIG. 7 also illustrates the method of forming a patterned aluminum layer according to the invention by electrolytic etching on the aluminum layer to be patterned.
In the step of forming a patterned aluminum layer, the temperature TCC) of the electrolytic solution when the side etching amount Y of the patterned aluminum layer formed according to the present invention becomes zero. Current density J (MA/Cl
It is a figure showing the relationship of (t)). FIG. 8 is a cross-sectional view showing an example of a patterned aluminum layer obtained by the method of forming a patterned aluminum layer according to the present invention. 1・
... Substrate, 2... Insulating layer, 3... Insulating substrate, 4...
... Aluminum layer to be patterned, 5... Patterned mask layer, 6... Substrate body, 7... Patterned aluminum layer, 11... Electrolyte, 1
2... Tank, 13... Electrode, 14... DC power supply, 1
5...Voltmeter, 16...Ammeter.

Claims (1)

[Claims] 1. An aluminum layer to be patterned is formed on an insulating substrate, a patterned mask layer is formed on the aluminum layer, and then the mask layer is applied to the aluminum layer. A patterned aluminum layer characterized by forming a patterned aluminum layer by performing electrolytic etching using a mask and an electrolytic solution consisting of an aqueous solution containing phosphoric acid and nitric acid as main solutes. Method of forming an aluminum layer. 2. In the method for forming a patterned aluminum layer according to claim 1, the electrolytic etching is performed at a temperature T (°C) of the electrolytic solution at a current density J (mA/cm ^2), Te=a・Je+ba
= 2.6 (1 ± 0.1) b = 17.5 (1 ± 0.1) Patterned aluminum characterized by carrying out at a current density equal to or higher than Je (mA/cm^2) given by b = 17.5 (1 ± 0.1) How to form layers. 3. In the method for forming a patterned aluminum layer according to claim 1, the electrolytic etching is performed at a current density J (mA/cm^2) of Je (mA/cm^2).
m^2), and the temperature T (℃) of the electrolyte is Te=a
・Je + b a=2.6 (1±0.1) b=17.5 (1±0.1) A patterned aluminum layer characterized by being formed at a temperature below Te (℃) given by a=2.6 (1±0.1) How to form. 4 Forming an aluminum layer to be patterned on an insulating substrate, forming a patterned mask layer on the aluminum layer, and then applying phosphoric acid to the aluminum layer using the mask layer as a mask. Electrolytic etching is performed using an electrolytic solution consisting of an aqueous solution containing nitric acid and nitric acid as main solutes, using the aluminum layer to be patterned as the anode, and the aluminum layer to be patterned as the anode and the cathode electrode corresponding thereto. patterned aluminum by connecting a direct current constant current source between the electrodes and increasing the voltage between the aluminum layer to be patterned as anode and the cathode electrode to a point where it suddenly becomes large. A method of forming a patterned aluminum layer comprising forming a layer. 5. In the method for forming a patterned aluminum layer according to claim 4, the electrolytic etching is performed at a temperature T (°C) of the electrolytic solution at Te (°C) and a current density J (mA/°C).
cm^2), Te=a・Je+ba=2.6(1±0
．． 1) A method for forming a patterned aluminum layer, characterized in that it is carried out at a current density equal to or higher than Je (mA/cm^2) given by b=17.5 (1±0.1). 6. In the method for forming a patterned aluminum layer according to claim 4, the electrolytic etching is performed at a current density J (mA/cm^2) of Je (mA/cm^2).
m^2), and the temperature T (℃) of the electrolyte is Te=a
・Je + b a=2.6 (1±0.1) b=17.5 (1±0.1) A patterned aluminum layer characterized by being formed at a temperature below Te (℃) given by a=2.6 (1±0.1) How to form. 7 Forming an aluminum layer to be patterned on an insulating substrate, forming a patterned mask layer on the aluminum layer, and then applying phosphoric acid to the aluminum layer using the mask layer as a mask. Electrolytic etching is performed using an electrolytic solution consisting of an aqueous solution containing nitric acid and nitric acid as main solutes, using the aluminum layer to be patterned as the anode, and the aluminum layer to be patterned as the anode and the cathode electrode corresponding thereto. A constant DC voltage source is connected between the lines, and the current flowing from the constant DC voltage source through the aluminum layer to be patterned as the anode suddenly becomes small. 1. A method of forming a patterned aluminum layer, the method comprising: forming a patterned aluminum layer. 8. In the method of forming a patterned aluminum layer according to claim 7, the electrolytic etching comprises:
The temperature T (°C) of the above electrolyte is Te (°C), and the current density J (mA/cm^2) is Te=a・Je+ba=2
．． 6(1±0.1)b=17.5(1±0.1) Forming a patterned aluminum layer characterized by carrying out at a current density of Je(mA/cm^2) or higher given by b=17.5(1±0.1) how to. 9 In the method for forming a patterned aluminum layer according to claim 7, the electrolytic etching is performed at a current density J (mA/cm^2) of Je (mA/cm^2).
m^2), and the temperature T (℃) of the electrolyte is Te=a
・Je + b a=2.6 (1±0.1) b=17.5 (1±0.1) A patterned aluminum layer characterized by being formed at a temperature below Te (℃) given by a=2.6 (1±0.1) How to form.