JP6696441B2 - Wet etching equipment - Google Patents

Description

  The present invention relates to a wet etching apparatus.

  Patent Document 1 discloses a wet etching apparatus for processing a silicon wafer by wet etching. Wet etching of a silicon wafer is generally performed with an etching solution at a high temperature. At this time, the vapor generated from the etching solution enters a gap or the like formed in the operating part of the wet etching apparatus.

  The vapor that enters the gap is liquefied and remains there. Every time wet etching is performed a plurality of times, this residual liquid is concentrated and becomes high in concentration. As described above, the residual etching solution remaining in the gap may adhere to an operator when the wet etching apparatus is disassembled and maintenance work is performed, which may damage clothes. In addition, there is a possibility of damaging equipment around the wet etching apparatus. However, it is difficult to remove the residual etching solution that has entered such a gap only by washing with running water.

JP, 2013-55302, A

  The present invention has been made in view of the above problems, and an object thereof is to provide a wet etching apparatus capable of reliably removing a high-concentration residual etching solution.

The wet etching apparatus (1) of the present invention has an accommodation space (30) capable of accommodating an object to be processed (14), and an etching tank (15) capable of wet etching the object to be processed accommodated in the accommodation space. ), An etching liquid tank (50) capable of storing the etching liquid and allowing the etching liquid to flow into the etching tank, and a cleaning liquid tank (40) capable of storing the cleaning liquid and allowing the cleaning liquid to flow into the etching tank. Prepare
Further, a discharge pipe (72, 84) for discharging the cleaning liquid or the etching liquid to the outside of the etching tank, and a vapor of the cleaning liquid generated in the accommodation space provided in the etching tank , or a steam is introduced into the accommodation space from the outside. And a steam generating part (60) capable of operating.
The cleaning liquid is introduced into the cleaning liquid tank, and the cleaning liquid is vaporized by the steam generator. The vaporized cleaning liquid enters the gap of the etching tank and is liquefied there. As a result, the high-concentration residual etching solution remaining in the gap is neutralized and removed.

It is explanatory drawing of the wet etching apparatus which concerns on 1st embodiment of this invention. 6 is a flowchart showing an operation during wet etching of a silicon wafer using the wet etching apparatus according to the first embodiment of the present invention. 6 is a flowchart showing a pre-maintenance cleaning operation of the wet etching apparatus according to the first embodiment of the present invention. It is a characteristic view of a pre-maintenance cleaning operation and a normal cleaning operation according to the first embodiment of the present invention. It is explanatory drawing of the wet etching apparatus which concerns on 2nd embodiment of this invention. It is a flowchart which shows the cleaning operation before maintenance of the wet etching apparatus which concerns on 2nd embodiment of this invention. It is explanatory drawing of the wet etching apparatus which concerns on 3rd embodiment of this invention. It is a flowchart which shows the cleaning operation before maintenance of the wet etching apparatus which concerns on 3rd embodiment of this invention. It is explanatory drawing of the wet etching apparatus which concerns on 4th embodiment of this invention. It is a flowchart which shows the cleaning operation before maintenance of the wet etching apparatus which concerns on 4th embodiment of this invention. It is explanatory drawing of the wet etching apparatus which concerns on 5th embodiment of this invention. It is a flowchart which shows the cleaning operation before maintenance of the wet etching apparatus which concerns on 5th embodiment of this invention.

Hereinafter, a wet etching apparatus according to an embodiment of the present invention will be described with reference to the drawings. Note that, in the following plural embodiments, the same reference numerals are given to the same components, and the description thereof will be omitted.
(First embodiment)
FIG. 1 shows a wet etching apparatus 1 according to the first embodiment of the present invention. The wet etching apparatus 1 is applied to wet etching of a silicon wafer 14 as a “processed object”. Hereinafter, the direction of gravity is defined as downward and the opposite direction is defined as upward.

  The wet etching apparatus 1 includes an upper unit 10 and a lower unit 20 which are vertically separable. The upper unit 10 includes an etching bath 15 made of fluororesin. The lower unit 20 includes a lower unit structure 25. The O-ring 12 is fitted between the etching bath 15 and the lower unit structure 25 to ensure water tightness. The upper and lower parts are separated by lifting the etching tank 15 upward by an operating device (not shown).

The O-ring 16 is fitted between the silicon wafer 14 and the lower unit structure 25 to ensure water tightness. The O-ring 18 is fitted between the silicon wafer 14 and the etching bath 15 to ensure watertightness. These two O-rings not only serve to ensure watertightness, but also serve to sandwich and fix the silicon wafer 14 from above and below.
The etching tank 15 forms an upper wall and a side wall of the accommodation space 30, and the silicon wafer 14 is a material to be etched and simultaneously forms a bottom wall of the accommodation space 30.

  The lower unit 20 includes a push-up rod 22 made of a fluororesin that lifts the silicon wafer 14 after the etching operation is completed. The push-up rod 22 is moved upward by a cylinder (not shown), hits the lower surface of the silicon wafer 14, and can move the silicon wafer 14 upward.

  The upper unit 10 includes a cleaning liquid tank 40, an etching liquid tank 50, a cleaning liquid discharge port 70, a discharge tank 80, a first receiving portion 44, a second receiving portion 54, a heater 60, an electrode 66, a stirring rod 94 and a stirring blade 96. ..

  The cleaning liquid tank 40 is located above the etching tank 15 and includes a first pipe 46 that is a cleaning liquid inflow pipe. The first pipe 46 includes a first valve 48 and a cleaning liquid inlet 42. When the first valve 48 is open, the cleaning liquid tank 40 communicates with the accommodation space 30, and when the first valve 48 is closed, the cleaning liquid tank 40 is separated from the accommodation space 30. The first receiving portion 44 is located below the cleaning liquid inlet 42, temporarily receives the cleaning liquid falling from the cleaning liquid tank 40, and weakens the falling force of the cleaning liquid. If the first receiving portion 44 is not provided, the force of the cleaning liquid dropping becomes too strong, and the silicon wafer 14 may be damaged by the pressure of the falling cleaning liquid.

  The etching liquid tank 50 is located above the etching tank 15 and includes a second pipe 56 that is an etching liquid inflow pipe. The second pipe 56 includes a second valve 58 and an etching solution inlet 52. When the second valve 58 is open, the etching solution tank 50 communicates with the accommodation space 30, and when the second valve 58 is closed, the etching solution tank 50 is separated from the accommodation space 30. The second receiving portion 54 is located below the etching liquid inlet 52, and temporarily receives the etching liquid falling from the etching liquid tank 50, and weakens the force of the etching liquid dropping. If the second receiving portion 54 is not provided, the momentum of the dropping of the etching solution becomes too strong, and the silicon wafer 14 may be damaged by the pressure of the dropping etching solution.

  The cleaning liquid discharge port 70 is located on the side surface of the etching tank 15 and includes a third pipe 72 as a “discharge pipe”. The third pipe 72 includes a third valve 74. When the third valve 74 is open, the cleaning liquid discharge port 70 communicates with the outside (not shown), and the liquid in the storage space 30 is discharged. When the third valve 74 is closed, the cleaning liquid discharge port 70 is disconnected from the outside. Be done.

  The discharge tank 80 is located on the lower side surface of the etching tank 15 and includes a fourth pipe 84 as a “discharge pipe”. The discharge tank 80 is connected to a vacuum pump (not shown) so that the inside of the discharge tank 80 can be evacuated. The fourth pipe 84 includes a fourth valve 86 and an etching solution discharge port 82. When the fourth valve 86 is open, the discharge tank 80 communicates with the accommodation space 30. Since the inside of the discharge tank 80 is vacuum, the liquid in the storage space 30 is sucked into the discharge tank 80 and discharged. When the fourth valve 86 is closed, the discharge tank 80 is separated from the accommodation space 30. Six discharge tanks 80 are formed in the wet etching apparatus 1.

  The heater 60 is located below the etching bath 15. The heater 60 is a spiral heating wire 62 made of nichrome. Since the heating wire 62 corrodes when it comes into contact with the etching solution, a coating 64 of a fluororesin covers the heating wire 62. The heater 60 is electrically connected to a power source (not shown) and can heat the etching liquid and the cleaning liquid.

The stirring blade 96 is located below the etching tank 15 and has a propeller shape, and is joined to one end of a cylindrical stirring rod 94. The other end of the stirring rod 94 is connected to the motor 90. When the motor 90 applies a rotating motion to the stirring rod 94, the stirring blade 96 also rotates to stir the etching liquid and the cleaning liquid.
The stirring rod 94 penetrates the etching bath 15 through the opening 98 opened in the etching bath 15, and is connected to the motor 90. The O-ring 92 is fitted between the stirring rod 94 and the etching tank 15 in order to prevent the etching liquid from leaking. Therefore, the etching tank 15 and the stirring rod 94 do not come into close contact with each other, and a minute space S exists between the upper unit 10 and the stirring rod 94.

  The electrode 66 is an electrode made of Pt (platinum) and is provided below the etching bath 15 at a position close to the silicon wafer. The electrode 66 is used for passing a current through the etching solution when the silicon wafer 14 is processed by electrochemical wet etching.

Next, the operation of the wet etching apparatus 1 during wet etching will be described with reference to FIG.
The upper unit raising process of step S1 will be described.
The upper unit 10 is separated from the lower unit 20 and lifted by a driving unit (not shown).

The silicon wafer loading process of step S2 will be described.
The silicon wafer 14 to be processed is placed on the O-ring 16. The work of mounting the silicon wafer may be performed by an operator or may be performed by a mechanical device such as a robot.

The step of lowering the upper unit 10 in step S3 will be described.
The upper unit 10 is lowered by a driving unit (not shown). The O-ring 12 is fitted between the etching tank 15 and the lower unit structure 25, and the etching tank 15 and the lower unit structure 25 are integrated.
Further, the O-ring 18 is fitted between the etching tank 15 and the silicon wafer 14. Therefore, the silicon wafer 14 is sandwiched and fixed between the O-ring 16 and the O-ring 18 from above and below. As a result, the silicon wafer 14 forms the bottom wall of the accommodation space 30.

The step of adding the etching liquid in step S4 will be described.
The composition of the etching solution is a 20% aqueous solution of TMAH (tetramethylammonium hydroxide), which has strong alkalinity.
When the second valve 58 is opened, the etching liquid is introduced into the accommodation space 30 from the etching liquid tank 50 through the second pipe 56. When the amount of the etching liquid becomes constant, the second valve 58 is closed and the supply of the etching liquid is stopped. The etching liquid once falls into the accommodation space 30 after the momentum of the fall on the second receiving portion 54 is attenuated.

The etching process in step S5 will be described.
When the supply of the etching liquid is stopped, the power of the heater 60 is turned on. When the heater 60 is energized, the heating wire 62 generates heat to heat the etching solution. The target temperature of the etching solution is 90 ° C. A controller (not shown) that works in conjunction with a liquid thermometer (not shown) that measures the temperature of the etching solution controls the amount of current supplied to the heater 60.
The stirring rod 94 and the stirring blade 96 are rotated to generate convection in the etching solution so that no temperature distribution is generated in the etching solution.

The silicon in the silicon wafer is dissolved in the etching solution by the reaction of the following formula (1), and gradually becomes thin.
Si ten 2OH ^- ten _{2H 2 O → Si (OH 2} ) O 2 2- ten 2H ₂ ··· (1)

At this time, a negative voltage is applied to the electrode 66, and a positive voltage is applied to the back side of the surface to be etched of the silicon wafer 14. When the silicon wafer has a certain thickness, an electric current flows from the back side of the surface to be etched of the silicon wafer to the etching solution. When a current flows, an oxide film SiO ₂ is formed on the silicon wafer according to the following formula (2).
Si + 2OH ⁻ + 2e ⁻ → SiO ₂ + H ₂ (2)
The etching solution does not dissolve the oxide film SiO ₂ .

Here, there is a correlation between the amount of current flowing between the electrode 66, the silicon wafer 14 and the etching solution, and the thickness of the oxide film SiO ₂ . Therefore, by adjusting the voltage applied to the electrode 66 and the back side of the surface to be etched of the silicon wafer 14, the silicon wafer 14 can be etched to a target thickness.
When the etched portion of the silicon wafer 14 has been etched to the target thickness, the energization of the heater 60 and the voltage application to the electrode 66 and the back side of the etched surface of the silicon wafer are stopped. Further, the rotation of the stirring rod 94 and the stirring blade 96 is stopped.

The etching liquid discharging step of step S6 will be described.
The fourth valve 86 is opened. The discharge tank 80 is evacuated by a vacuum pump (not shown). Therefore, the etching liquid held in the accommodation space 30 is discharged to the discharge tank 80 through the fourth pipe 84. Then, when the etching liquid remaining in the accommodation space 30 is completely discharged, the fourth valve 86 is closed.

The cleaning process of step S7 will be described.
The cleaning liquid used in this embodiment is ultrapure water. The cleaning liquid has a role of cleaning the silicon wafer 14 and the etching bath 15.
When the first valve 48 is opened, the cleaning liquid is introduced into the accommodation space 30 from the cleaning liquid tank 40 through the first pipe 46. When the amount of the cleaning liquid reaches a certain level, the first valve 48 is closed and the injection of the cleaning liquid is stopped. The cleaning liquid once falls on the first receiving portion 44, and then the momentum of the fall is attenuated, and then the cleaning liquid falls into the accommodation space 30. After that, it is left for about 5 minutes until the etching liquid remaining at the bottom of the accommodation space 30 and the cleaning liquid are sufficiently mixed.

After that, the third valve 74 is opened, and the cleaning liquid is discharged to the outside from the cleaning liquid discharge port 70 through the third pipe 72.
The cleaning liquid below the lower limit L2 of the cleaning liquid outlet 70 does not flow out from the cleaning liquid outlet 70. Therefore, the fourth valve 86 is opened and the cleaning liquid is discharged to the discharge tank 80.
When the cleaning liquid remaining in the storage space 30 is completely discharged, the fourth valve 86 is closed.
The cleaning operation of step S7 may be repeated a plurality of times as necessary.

The upper unit raising process of step S8 will be described.
Similar to step S1, the upper unit 10 is separated from the lower unit 20 and lifted by a drive unit (not shown).

The silicon wafer unloading step of step S9 will be described.
The push-up rod 22 is driven upward by a cylinder (not shown). As a result, the silicon wafer 14 is supported by the push-up bar 22. Then, the silicon wafer 14 is carried out outside. The work of unloading the silicon wafer may be performed by an operator or may be performed by a mechanical device such as a robot.
After carrying out the silicon wafer 14, the push-up bar 22 is returned to the original position.

When another silicon wafer is to be continuously etched after the silicon wafer unloading process is completed, the process proceeds to step S2, the other silicon wafer is placed on the O-ring 16, and the etching operation is continued.
If another silicon wafer is not etched, the etching operation ends.

Next, the maintenance work of the wet etching apparatus 1 will be described.
The wet etching apparatus 1 is a single wafer type, and the upper unit 10 and the lower unit 20 are separated each time the silicon wafer 14 is replaced. Therefore, a load is applied to the O-ring 16 and the O-ring 18 that hold down the silicon wafer 14 that forms the bottom wall, and the O-ring 12 that is between the etching tank 15 and the lower unit structure 25. If this is done, the O-ring will deteriorate. The deteriorated O-ring cannot ensure water tightness and causes liquid leakage.

In this way, if the upper unit 10 and the lower unit 20 are configured so that they are separated each time one silicon wafer 14 is etched, the O-ring deteriorates quickly and the replacement cycle becomes frequent.
In addition, if mechanical parts or the like are deteriorated or the silicon wafer is damaged during etching, it is necessary to disassemble the wet etching apparatus 1 and perform maintenance work.
Workers perform O-ring replacement work and maintenance work after disassembling the device.

The wet etching apparatus 1 performs wet etching in a state where the TMAH aqueous solution has a high temperature. Therefore, the vapor generated from the TMAH aqueous solution having a high temperature fills the inside of the apparatus during etching.
When such vapor enters a place where the cleaning liquid does not reach, such as the upper surface 45 of the first receiving portion 44, the upper surface 55 of the second receiving portion 54, or a narrow gap such as the space S, it is liquefied again. Every time etching is performed a plurality of times, the remaining etching liquid is concentrated and becomes high in concentration.
Such an area where the cleaning liquid does not reach or the etching liquid that has entered the narrow gap cannot be removed by the cleaning work during etching as shown in step S7, and remains in the gap.

Therefore, when the operator tries to replace the O-ring, the etching solution that remains in the gap leaks. The leaked etching solution may adhere to the worker's clothes and damage the clothes. Alternatively, the leaked etchant may damage the wet etching apparatus 1 and the mechanical equipment and electric equipment around the wet etching apparatus 1 and damage the equipment.
Therefore, before the maintenance work, it is necessary to clean the wet etching apparatus 1 to remove the etching liquid that remains in the gap.

Next, the pre-maintenance cleaning will be described.
FIG. 3 shows a flowchart of the pre-maintenance cleaning operation of the wet etching apparatus 1.
The cleaning liquid introducing step of step S11 will be described.
Ultrapure water is used as the cleaning liquid.
When the first valve 48 is opened, the cleaning liquid is introduced into the accommodation space 30 from the cleaning liquid tank 40 through the first pipe 46. When the amount of the cleaning liquid reaches a certain amount (in the present embodiment, the liquid level exceeds the upper limit L1 of the cleaning liquid discharge port 70), the first valve 48 is closed and the injection of the cleaning liquid is stopped.

The cleaning liquid heating step of step S12 will be described.
The heater 60 is energized to heat the cleaning liquid. The target temperature of the cleaning liquid is 100 ° C. A controller (not shown) that works in conjunction with a liquid thermometer (not shown) that measures the temperature of the cleaning liquid controls the amount of current supplied to the heater 60.
The stirring rod 94 and the stirring blade 96 are rotated to generate convection in the cleaning liquid so that no temperature distribution is generated in the cleaning liquid.

The steam neutralization step of step S13 will be described.
The cleaning liquid heated by the heater 60 boils to generate the cleaning liquid vapor. The generated vapor of the cleaning liquid fills the accommodation space 30, enters the narrow gaps such as the upper surface 45 of the first receiving portion 44, the upper surface 55 of the second receiving portion 54, and the space S, and is liquefied again there. The liquefied cleaning liquid is mixed with the remaining etching liquid to dilute the concentration of the etching liquid and neutralize it. 15 minutes after the temperature of the cleaning liquid reaches 100 ° C., the heater 60 is energized and the rotation of the stirring rod 94 and the stirring blade 96 is stopped.

The cleaning liquid discharging step of step S14 will be described.
The third valve 74 is opened, and the cleaning liquid is discharged to the outside from the cleaning liquid discharge port 70 through the third pipe 72. Since the cleaning liquid below the lower limit L2 of the cleaning liquid discharge port 70 does not flow outside, the fourth valve 86 is opened and the cleaning liquid is discharged to the discharge tank 80.
When the cleaning liquid remaining in the storage space 30 is completely discharged, the fourth valve 86 is closed.
In this way, the pre-maintenance cleaning operation is completed.

  After the pre-maintenance cleaning operation is completed, the upper unit 10 is moved upward, and the worker performs maintenance work such as replacement of the O-ring.

The effects of this embodiment will be described.
FIG. 4 shows a characteristic diagram in which the pH of the etching liquid remaining in the gap is compared between the cleaning before maintenance and the normal cleaning work.
The PH of the remaining etching liquid was measured by sucking the liquid remaining in the gap with a dropper or the like and using a PH meter.

As shown in FIG. 4A, the pH of the liquid remaining in the space S between the stirring rod 94 and the etching tank 15 is the strong alkalinity of PH14 after the cleaning process of step S7, but After passing through the vapor neutralization step of step S13 in the pre-cleaning, PH8 is weakly alkaline.
As shown in FIG. 4B, the liquid PH remaining on the upper surface 55 of the second receiving portion 54 is the strong alkaline of PH13 of step S7, but the vapor neutralization step of step S13 in the cleaning before maintenance is performed. After a while, it has become weak alkaline of PH8.
Thus, it can be seen that the etching liquid remaining in the gap is sufficiently neutralized by the vapor of the cleaning liquid generated by heating the cleaning liquid.

  If the cleaning liquid discharge port 70 is further arranged above the accommodation space 30 and a large amount of cleaning liquid is introduced, the cleaning liquid reaches the upper surface 55 of the second receiving portion 54. Therefore, it is possible to remove the high-concentration residual etching solution by the cleaning process in step S7. However, in the space S, the cleaning liquid does not reach the space S because air is trapped. Therefore, the cleaning liquid is heated to generate steam and a steam neutralization process is performed.

As described above, as the pre-maintenance cleaning, the pH of the etching liquid remaining in the gap can be significantly reduced by heating the cleaning liquid to generate steam and performing the steam neutralization treatment for neutralizing the etching liquid. it can.
As a result, even if the residual etching solution leaks out during the maintenance work after the worker disassembles the wet etching apparatus 1, it is not a strong alkali, so that it does not damage the clothes even if it adheres to the clothes. , Even if it adheres to external equipment, it will not damage the equipment.

(Second embodiment)
A wet etching apparatus 100 according to the second embodiment of the present invention will be described. As shown in FIG. 5, the wet etching apparatus 100 further includes an ultrasonic vibrator 105 made of piezoelectric ceramics.
The operation of the wet etching apparatus 100 during etching is the same as in the first embodiment.

Next, maintenance work using the wet etching apparatus 100 according to this embodiment will be described. In this embodiment, only the pre-maintenance cleaning operation is different from the first embodiment, and only that point will be described in detail.
FIG. 6 shows a flowchart of the pre-maintenance cleaning operation of the wet etching apparatus 100.
The cleaning liquid introducing step of step S21 will be described. Step S21 is the same as step S11 according to the first embodiment.

The steam neutralization step of step S22 will be described.
A high frequency AC voltage is applied to the ultrasonic transducer 105. The vibration energy of the generated ultrasonic waves is transmitted to the water surface and a part of the water surface rises, and fine cleaning liquid vapor is generated. The generated cleaning liquid vapor enters the narrow gaps such as the upper surface 45 of the first receiving portion 44, the upper surface 55 of the second receiving portion 54, and the space S, and is liquefied again there. Then, it is mixed with the remaining etching liquid, and the concentration of the etching liquid is thinned and neutralized. After 15 minutes, the application of the high frequency AC voltage to the ultrasonic transducer is stopped.

The cleaning liquid discharging step of step S23 will be described.
The third valve 74 is opened, and the cleaning liquid is discharged to the outside from the cleaning liquid discharge port 70 through the third pipe 72. Since the cleaning liquid below the lower limit L2 of the cleaning liquid discharge port 70 does not flow out of the cleaning liquid discharge port 70, the fourth valve 86 is opened and the cleaning liquid is discharged to the discharge tank 80. When the cleaning liquid remaining in the storage space 30 is completely discharged, the fourth valve 86 is closed. This completes the pre-maintenance cleaning.

In this embodiment, the ultrasonic transducer 105 is used to generate steam. The ultrasonic vibrator 105 can generate the cleaning liquid vapor more efficiently with lower power than the heater.
Therefore, in this embodiment, in addition to the effects of the first embodiment, the electric power required for steam neutralization can be reduced.

(Third embodiment)
A wet etching apparatus 200 according to the third embodiment of the present invention will be described. As shown in FIG. 7, the wet etching apparatus 200 further includes a vapor introducing pipe 205. One of the steam introducing pipes 205 is connected to the outside boiler 207 and the other is connected to the accommodation space 30. The boiler 207 can generate a large amount of steam.
When the fifth valve 206 is open, the storage space 30 communicates with the boiler 207, and when the fifth valve 206 is closed, the storage space 30 and the boiler 207 are shut off.
The operation of the wet etching apparatus 200 during etching is the same as in the first embodiment.

Next, maintenance work using the wet etching apparatus 200 according to the present embodiment will be described. In this embodiment, only the pre-maintenance cleaning operation is different from the first embodiment, and only that point will be described in detail.
FIG. 8 shows a flowchart of the pre-maintenance cleaning operation of the wet etching apparatus 200. The steam neutralization step of step S31 will be described.
The fifth valve 206 of the steam introducing pipe 205 is opened and the steam generated by the boiler 207 is introduced into the wet etching apparatus 200.

  The introduced water vapor enters the narrow gaps such as the upper surface 45 of the first receiving portion 44, the upper surface 55 of the second receiving portion 54, and the space S, and is liquefied again there. Then, it is mixed with the remaining etching liquid, and the concentration of the etching liquid is thinned and neutralized. After 15 minutes, the fifth valve 206 is closed to stop the introduction of steam.

The discharging step of step S32 will be described.
The fourth valve 86 is opened and the liquefied vapor is discharged to the discharge tank 80.
When the liquid remaining in the storage space 30 is completely discharged, the fourth valve 86 is closed.
This completes the pre-maintenance cleaning.

In this embodiment, water vapor is introduced from the outside. Therefore, a large amount of steam generated outside can be sent in, and the time required for steam neutralization can be reduced. For example, surplus steam generated in a boiler facility of a factory can be used.
Therefore, the wet etching apparatus 200 of this embodiment can reduce the power and time required for vapor neutralization more than the first and second embodiments.

(Fourth embodiment)
A wet etching apparatus 300 according to the fourth embodiment of the present invention will be described. As shown in FIG. 9, the wet etching apparatus 300 further includes a vacuum decompression tube 305 as a “decompression unit”. One of the vacuum decompression pipe 305 is connected to the vacuum pump 307 and the other is connected to the accommodation space 30.
When the sixth valve 306 is in the open state, the accommodation space 30 communicates with the external vacuum pump 307, and when the sixth valve 306 is in the closed state, the accommodation space 30 and the external vacuum pump 307 are shut off.
The operation of the wet etching apparatus 300 during etching is the same as in the first embodiment.

Next, maintenance work using the wet etching apparatus 300 according to the present embodiment will be described. In this embodiment, only the pre-maintenance cleaning operation is different from the first embodiment, and only that point will be described in detail.
FIG. 10 shows a flowchart of the pre-maintenance cleaning operation of the wet etching apparatus 300.
The cleaning liquid introducing step of step S41 will be described. Step S41 is the same as step S11 according to the first embodiment.

The etching tank pressure reducing step of step S42 will be described.
The sixth valve 306 is opened, the accommodation space 30 and the vacuum pump 307 are communicated with each other, and the accommodation space 30 is depressurized below atmospheric pressure. When the pressure has been reduced to some extent, the sixth valve 306 is closed and the accommodation space 30 and the vacuum pump 307 are shut off. The accommodation space 30 is maintained at a pressure lower than the atmospheric pressure.

The cleaning liquid heating step of step S43 will be described. Step S43 is the same as step S12 according to the first embodiment.
The steam neutralization step of step S44 will be described. Step S43 is the same as step S13 according to the first embodiment.
The cleaning liquid discharging step of step S45 will be described. Step S45 is the same as step S14 according to the first embodiment.

In this embodiment, since the accommodation space 30 is in a depressurized state, the boiling point of the cleaning liquid is lowered. Since the cleaning liquid boils at a lower temperature than when the pressure is not reduced, it is possible to reduce the electric power for heating the cleaning liquid.
Therefore, in this embodiment, in addition to the effects of the first embodiment, the electric power required for steam neutralization can be reduced.

(Fifth embodiment)
A wet etching apparatus 400 according to the fifth embodiment of the present invention will be described. As shown in FIG. 11, the wet etching apparatus 400 further includes a cleaning liquid heating heater 405 as a heating unit in the cleaning liquid tank 40.
The operation of the wet etching apparatus 400 during etching is the same as in the first embodiment.

Next, maintenance work using the wet etching apparatus 400 according to this embodiment will be described. In this embodiment, only the pre-maintenance cleaning operation is different from the first embodiment, and only that point will be described in detail.
FIG. 12 shows a flowchart of the pre-maintenance cleaning operation of the wet etching apparatus 400.
The cleaning liquid preheating step of step S51 will be described. The cleaning liquid heating heater 405 provided in the cleaning liquid tank 40 heats the cleaning liquid. When heated to a temperature above the boiling point, the tank is damaged by pressure, so the heating temperature is 90 ° C.

The cleaning liquid introducing step of step S52 will be described. Step S52 is the same as step S11 according to the first embodiment.
The cleaning liquid heating step of step S53 will be described. Step S53 is the same as step S12 according to the first embodiment.
The steam neutralization step of step S54 will be described. Step S54 is the same as step S13 according to the first embodiment.
The cleaning liquid discharging step of step S55 will be described. Step S55 is the same as step S14 according to the first embodiment.

Since the preheated cleaning liquid is introduced into the accommodation space 30, it is possible to reduce the time and power required to heat the cleaning liquid and generate the vapor of the cleaning liquid in step S53.
Therefore, in the present embodiment, in addition to the effect of the first embodiment, the steam neutralization can be performed in a shorter time and power.

(Sixth embodiment)
A wet etching apparatus according to the sixth embodiment of the present invention will be described. The wet etching apparatus according to the present embodiment is an apparatus for etching a glass wafer using HF (hydrofluoric acid), instead of an apparatus for etching a silicon wafer using TMAH.
The operation of the wet etching apparatus during etching and the operation during maintenance are the same as in the above embodiment.

  Even if the etching liquid is HF instead of TMAH, the pH of the liquid remaining in the gap can be brought close to 7 by performing the pre-maintenance cleaning, and the same effect as in the above embodiment can be obtained.

(Other embodiments)
(A) As an etching solution used for wet etching of silicon wafers and glass wafers, for example, KOH (potassium hydroxide), NH ₄ (ammonia), HNO ₃ (nitric acid), H ₂ SO ₄ (sulfuric acid), HCl ( There are various types such as hydrochloric acid) and KI (potassium iodide). The wet etching apparatus of the present invention can be applied to all the above-mentioned etching solutions and their mixed solutions.
(B) The present invention can also be applied to a wet etching apparatus that processes silicon wafers and glass wafers in a batch process.
(C) The present invention can also be applied to a wet processing apparatus that processes an object to be processed by using an organic solvent such as alcohol in place of the acid or alkaline liquid.
The present invention may be implemented by the above embodiments alone or in combination. Further, the present invention is not limited to the above-described embodiment, but can be implemented in various forms without departing from the spirit of the invention.

1, 100, 200, 300, 400 Wet etching device 14 Silicon wafer (processing target)
15 etching tank 30 accommodation space 40 cleaning liquid tank 50 etching liquid tank 72 third pipe (discharge pipe), 84 fourth pipe (discharge pipe)
60 heater, 105 ultrasonic transducer, 205 vapor introduction pipe 305 vacuum decompression pipe, 405 cleaning liquid heating heater

Claims (8)

An etching tank (15) having a storage space (30) capable of storing the object to be processed (14) and capable of wet etching the object to be processed housed in the accommodation space;
An etching liquid tank (50) capable of storing the etching liquid and allowing the etching liquid to flow into the accommodation space;
A cleaning liquid tank (40) capable of storing a cleaning liquid for cleaning the etching tank and allowing the cleaning liquid to flow into the accommodation space;
A discharge pipe (72, 84) for discharging the cleaning liquid or the etching liquid to the outside of the accommodation space;
A steam generation unit (60, 105, 205) provided in the etching tank for generating steam of the cleaning liquid in the storage space or capable of introducing steam from the outside into the storage space ;
The wet etching apparatus (1, 100, 200, 300, 400) provided with.   The wet etching apparatus according to claim 1, wherein the vapor generating unit is a heater (60) provided in the etching tank.   The wet etching apparatus according to claim 1, wherein the vapor generating unit is an ultrasonic vibrator (105) provided in the etching tank. The steam generating unit, a wet etching apparatus according to claim 1, wherein the steam inlet pipe for introducing steam (205) or outside et before Symbol accommodating space of the wet etching apparatus.   The wet etching apparatus according to claim 1, further comprising a decompression unit (305) capable of lowering the pressure of the accommodation space below atmospheric pressure.   The wet etching apparatus according to claim 1, further comprising a heating unit (405) capable of heating the cleaning liquid in the cleaning liquid tank.   The wet etching apparatus according to claim 1, wherein the discharge pipe communicates with a discharge tank (80) capable of lowering an internal pressure thereof below atmospheric pressure.   The wet etching apparatus according to claim 1, wherein a bottom wall of the accommodation space is formed of the object to be processed.

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