JP3525791B2 - Surface treatment equipment - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface treatment apparatus for performing etching treatment, plating treatment, etc. on the surface of a semiconductor wafer, which is suitable for use in manufacturing a semiconductor pressure sensor, a semiconductor acceleration sensor, etc. It is a thing.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 6, several hundreds to several thousands of recesses 72 are formed on a semiconductor wafer 70 using an etching solution such as potassium hydroxide (KOH aqueous solution), and pressure sensors and Manufactures semiconductor sensors such as acceleration sensors.

In these manufacturing processes, various jigs 75 as shown in FIG. 7 are used for masking them from the processing liquid in order to protect semiconductor circuits and power supply electrodes. For example, in the etching process, each chip 71 on the semiconductor wafer 70 of FIG. 6 has an island-shaped bulge in the center and an anisotropic etching solution such as potassium hydroxide around the chip 71 as shown in detail in FIG. Then, the concave portion 72 is made by melting it and the acceleration sensor is manufactured.

In this processing step, as shown in FIG. 8, a mask 76 is formed on the wafer 70 and the surface to be etched is dipped in a strong alkali such as potassium hydroxide at a high temperature.
The recess 72 is formed by anisotropic etching.

As the etching method, a dipping method has been generally used. For example, as shown in FIG. 7, the circuit surface and the edge surface of the wafer 70 are masked with a wax 74 on a plate 73 having high corrosion resistance such as ceramic so that only the surface to be etched is dissolved in the etching solution. And
As shown in FIG. 9, masking jigs 75 for masking the wafer 70 are arranged side by side in the carrier 80, and are immersed in the etching liquid 82 contained in the etching bath 81 until a desired etching amount is reached, and then not shown. Etching is stopped by transferring the wafer to a washing tank 83 with a transport device and immersing it in pure water 84. After sufficiently washing with water, the carrier 80 is taken out from the washing tank 83. After the pure water used for cleaning was dried, the wax 74 of FIG. 7 was dissolved by a solvent cleaning device (not shown) or the like, and the wafer 70 was removed from the plate 73.

In the dipping method consisting of such steps, since the entire masking jig 75 is dipped in the treatment liquid, impurities adhering during the masking work contaminate the treatment liquid, or the treatment liquid of a masking material such as wax is treated. This is a problem that leads to chronic quality defects in the wafer manufacturing process using high-purity chemicals.

In recent years, a sensor aiming at further miniaturization and high function has been developed, and as shown in FIG. 10, a square pyramidal cavity 8 is formed by directly etching the semiconductor circuit side surface.
5 is formed. In such a sensor, an etching solution containing an alkali metal such as potassium hydroxide which adversely affects the semiconductor circuit cannot be used. Therefore, an alkali solution such as an aqueous solution of tetramethylammonium hydroxide (hereinafter referred to as TMAH) is used. Has been. The etching process is carried out by setting a plurality of wafers on a carrier and using an etching apparatus similar to the conventional one, though the circuit surface is not masked.

TMAH is 10 times higher than KOH
CO in the atmosphere with a cheap etching solution ₂Has the property of absorbing
is there. Such an expensive and unstable etching solution
When used in the same etching equipment as
CO in addition to pollution₂Absorbs the liquid and decomposes the liquid,
The etching conditions become unstable, so the etching solution is frequently updated.
And stable production will be extremely difficult.
There was a problem.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and an object thereof is a surface treatment apparatus capable of effectively utilizing a treatment liquid while suppressing deterioration of the quality of the treatment liquid. To provide.

[0010]

According to the invention described in claim 1, the surface of the semiconductor wafer to be processed is surface-treated with the processing liquid in the surface processing bath, and the processing liquid after the surface treatment is a predetermined amount, excluding a part is drained. On the other hand, a part of the treatment liquid after the surface treatment is transferred to the regeneration treatment tank through the communication pipe. Then, in the regeneration treatment tank, the treatment liquid transferred through the communication pipe and a predetermined amount of new treatment liquid are mixed to regenerate the treatment liquid. The treatment liquid after the regeneration treatment in this regeneration treatment tank is transferred to the surface treatment tank through the communication pipe. The surface to be processed of the newly installed semiconductor wafer is surface-treated with this treatment liquid in the surface treatment tank. In this way, the treatment liquid is repeatedly used.

In this way, it is possible to effectively use the processing liquid while suppressing the deterioration of the quality of the processing liquid. According to the inventions of claims 4 and 5, the treatment liquid is transferred between the tanks by using a gas that does not contaminate the treatment liquid, the treatment liquid does not come into contact with air, and contamination of the liquid by air can be avoided.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows the overall configuration of the etching apparatus of this embodiment. In this etching apparatus, an etching unit 2 and an etching liquid management unit 3 are mounted on a table 1. Etching unit 2
Is for etching a silicon wafer 4 as a semiconductor wafer. The etching unit 2 closes an etching pot 5 for containing an etching solution, an etching base 6 on which the etching pot 5 is placed, and an upper opening of the etching pot 5. It is composed of an etching head 7. That is, by arranging the etching pot 5 so as to be sandwiched between the etching base 6 and the etching head 7, the airtightness inside the etching pot 5 can be maintained. Further, the etching liquid management unit 3 includes a sub pot 4 for preparing and circulating the etching liquid.
Has 0. The sub pot 40 is also used as a closed container like the etching pot 5.

FIG. 2 is an enlarged sectional view of the etching pot 5 in the etching unit 2, FIG. 3 is an enlarged sectional view of the etching base 6, and FIG. 4 is an etching head 7.
The expanded sectional view of is shown. Further, FIG. 5 shows an enlarged sectional view of the etching liquid management unit 3.

In FIG. 2, the etching pot 5 includes a plate-shaped wafer base 8 and a cylindrical wafer ring 9. Through hole 1 is formed in the center of wafer base 8.
0 is provided, and the wafer plate 11 is provided in the upper opening.
Are arranged so as to close the opening. The wafer plate 11 is made of, for example, stainless steel (SUS304).
It consists of a thin metal plate. The wafer plate 11 functions as a heat transfer plate for preheating and an electrode for electrochemical stop. A silicon wafer 4 can be placed on the upper surface of the wafer plate 11, and a wafer ring 9 is placed on the upper surface of the wafer plate 11 with one opening facing down. That is, the silicon wafer 4 is arranged so as to close the lower surface opening of the cylindrical wafer ring 9. In this way, the silicon wafer 4 is placed on the wafer base 8 at the center thereof. At this time, the wafer 4 is arranged so that the surface to be etched (the surface opposite to the circuit formation surface in the case of the sensor of FIG. 8 and the circuit formation surface in the case of the sensor of FIG. 10) faces upward. Also, the wafer base 8
A concave portion 12 is formed in an annular shape on the outer peripheral side of the wafer mounting portion in, and the projection 13 of the wafer ring 9 is fitted into the concave portion 12. In this way, the recess 12 has a function of alignment. Further, a flat seal surface S1 is formed in an annular shape on the outer peripheral side of the recess 12 in the wafer base 8 (around the wafer mounting portion), and the recess 14 is formed in an annular shape on the seal surface S1 to function as a vacuum pocket. To do.

A wafer-type seal packing 15 is fixed to the inner peripheral portion of the lower surface of the wafer ring 9, and the packing 15 is formed into a wafer shape so as to seal the upper surface of the edge portion of the silicon wafer 4. The wafer type seal packing 15 can seal against the etching liquid filled in the wafer ring 9. That is, the seal packing 15 is for liquid-tightly sealing the lower surface of the wafer ring 9 and the outer peripheral portion of the wafer 4 with the silicon wafer 4 placed on the wafer base 8. Further, a flat seal surface S2 is formed on the outer peripheral portion of the lower surface of the wafer ring 9.
Is formed in an annular shape, and the recess 16 is formed in an annular shape in the sealing surface S2, and functions as a vacuum pocket.

An annular X-shaped packing 17 is arranged between the sealing surface S1 of the wafer base 8 and the sealing surface S2 of the wafer ring 9. The X-shaped packing 17 having an X-shaped cross section is provided with connecting holes 17a so as to connect the upper and lower vacuum chambers at several locations (8 locations in the embodiment) on the circumference.
The vacuum pump 18 shown in FIG. 1 discharges the air in the recesses (vacuum pockets) 14 and 16 shown in FIG. 2 so that the vacuum pump 18 elastically deforms due to the differential pressure between the internal vacuum and the atmospheric pressure (X-shaped packing 17 The wafer base 8 and the wafer ring 9 are pulled together (when contracted), and are fixed in a state where the outer periphery of the silicon wafer 4 is sealed by the seal packing 15. This driving force (about 40 kg in the embodiment) acts as a sealing force for the wafer 4, but in the present embodiment, a sealing force of 1.4 kg / cm is obtained for the sealing length of the wafer 4.

As described above, the etching pot 5 is filled with the etching liquid as a processing liquid, and the bottom of the wafer 4 supports the wafer 4 with its outer peripheral portion sealed, and the surface to be etched of the wafer 4 contacts the etching liquid. It is composed.

In the etching base 6 of FIG. 3, a heater 21 for preheating is arranged on the base material 20,
The heater 21 is provided with a temperature sensor 22.
Further, an electrode 23 is provided on the base material 20. In the state of FIG. 1 in which the etching pot 5 is mounted on the etching base 6, the heater 21 and the wafer plate 11 are in contact with each other and thermally connected, and the heat generated by the heater 21 is etched through the wafer plate 11. The outer peripheral portion of the wafer 4 in the pot 5 can be heated. At this time, only the outer peripheral portion of the wafer 4 is heated, and the heat radiation amount at the outer peripheral portion of the etching pot 5 can be supplemented to perform a uniform heating operation. Further, in the state shown in FIG. 1, the electrode 23 of the etching base 6 contacts the wafer plate 11 and is electrically connected thereto.

The etching head 7 of FIG. 4 has a cap material 30 for closing the upper opening of the etching pot 5 . A pot packing 31 is provided on the lower surface of the cap member 30. The pot packing 31 closes the upper opening of the etching pot 5 in an airtight state. In this way, the airtightness inside the etching pot 5 is maintained.

A stirring blade 32 is suspended from the cap member 30, and the stirring blade 32 is rotated by driving a motor 33 to stir the etching solution. Further, a diffusion plate 34 is hung on the cap material 30, and the diffusion plate 34 is arranged so as to face the wafer 4 in the etching liquid. When the etching solution is stirred by the diffusion plate 34, the same solution is diffused and the diffusion plate 3
4 functions as an electrode for the electrochemical stop of the wafer. Further, a temperature sensor 35 is hung on the cap member 30, and the temperature of the etching solution is detected by the temperature sensor 35. Furthermore, the cap member 30 is provided with an air supply port 36, and an inert gas (here, nitrogen gas) as a gas that does not contaminate the etching liquid can be pressed into the etching pot 5 through the air supply port 36. Further, the cap member 30 is provided with a drainage port 37, and the liquid in the etching pot 5 can be drained to the outside through the drainage port 37. A liquid supply / drainage nozzle 38 hangs down from the cap member 30 so as to be movable up and down, and liquid can be supplied to and discharged from the etching pot 5 through the liquid supply / drainage nozzle 38.

The temperature controller 39 shown in FIG.
5 and the heater 21 are connected to each other, and the temperature controller 39 controls energization of the heater 21 so that the heater temperature and the etching solution temperature become predetermined temperatures.

In the etching liquid management unit 3 of FIG. 5, the sub-pot 40 is for stably heating and holding the etching liquid, and is supported by the base material 41. The etching solution 42 is injected into the sub pot 40. The etching liquid management unit 3 is provided with a stirrer 43, and the rotor 43 a of the stirrer 43 is attached to the sub pot 40.
The rotor 43a in the etching liquid 42 is rotated as the magnet 43b is rotated by the motor 43c, and the etching liquid 42 is agitated.

Here, the volume of the etching solution in the sub pot 40 is 1000 cc, and the etching pot 5 described above is used.
Is equal to the volume of the etching solution. The sub pot 40
The volume of the etching solution may be larger than the volume of the etching solution in the etching pot 5.

A heater 44 is provided around the sub pot 40.
Are arranged. Further, the upper opening of the sub pot 40 is closed by the cap member 45 in an airtight state, and the cap member 4 is closed.
5 is provided with a drainage port 46, a supply / drainage nozzle 47, and an air supply pipe 48. Further, the temperature sensor 4 is attached to the cap member 45.
9 is hanging. Further, a temperature sensor 49 and a heater 44 are connected to the temperature controller 50, and the temperature controller 50 controls energization of the heater 44 so that the temperature of the etching solution by the temperature sensor 49 becomes a predetermined temperature.

In FIG. 1, a communication pipe 60 is provided between the etching unit 2 and the etching liquid management unit 3, and a supply / discharge liquid nozzle 38 and a supply / discharge liquid nozzle 47 are connected to each other.
Connected by 0. The communication pipe 60 is provided with an electromagnetic opening / closing valve C. Further, a communication pipe 61 is provided between the unit 2 and the unit 3, and the drainage port 37 and the drainage port 46 are connected by the communication pipe 61. Communication pipe 61
Is provided with electromagnetic opening / closing valves E1 and E2 in series, and a branch point a between the valves E1 and E2 is connected to a suction port of the ejector 62. Pure water is supplied to the ejector 62 through the electromagnetic opening / closing valve S3, and the pure water is supplied to the ejector 62, so that the ejector 62 performs a suction operation. Pure water can be supplied to the air supply port 36 of the etching unit 2 through the electromagnetic open / close valve S4. On the other hand, nitrogen gas can be supplied to the air supply port 36 of the etching unit 2 through the electromagnetic open / close valve S2 and can be supplied to the air supply pipe 48 of the etching liquid management unit 3 through the electromagnetic open / close valve S1.

Then, the etching solution can be circulated by opening the valve C and appropriately operating the nitrogen pressure feeding valves S1 and S2 and the evacuation valves E1 and E2.

Further, the diffusion plate 34 of the etching unit 2 and the electrode 23 are connected to the anodizing power supply device 63 of FIG. 1, and the voltage between the diffusion plate 34 and the wafer plate 11 is controlled by the anodizing power supply device 63. , The start / stop of etching on the wafer 4 is controlled by the anodic oxidation action.
Further, a liquid supply pump (not shown) for quantitatively supplying the etching liquid is provided as an incidental facility.

As described above, the etching pot 5 serving as an etching tank supports the wafer 4 serving as a bottom plate by arranging the surface to be etched of the wafer 4 upward in the wafer base 8 and supporting the wafer 4 by the cylindrical wafer ring 9. The face is masked. The pot 5 has an airtight structure, the subpot 40 heats and agitates the etching liquid while keeping the airtightness, and the two pots 5 and 40 are connected by using the communication pipe 60, and the insides of the pots 5 and 40 are connected. Nitrogen gas, which is an inert gas, can be used for scavenging (purging), and by pressurizing with the same gas, the etching solution can be pressure-fed to transfer the etching solution between the pots.

Regarding the wafer plate 11 built in the etching pot 5, the plate 11 protects the wafer 4 from deformation when the inside of the etching pot 5 is pressurized by an inert gas.

The etching apparatus is provided with a controller as a production control apparatus, and the controller controls the valves S1 to S4, E1, E2, C and the like.

In this embodiment, the etching pot 5 and the etching head 7 constitute a surface treatment bath, and the sub pot 40 and the cap material 45 constitute a regeneration treatment bath.

Next, the operation of the thus constructed etching apparatus (procedure of etching work) will be described. As a preparation before starting the etching process, the valve C provided in the communication pipe 60 of FIG. 1 is closed, the valves E1 and S1 are opened, the inside of the sub pot 40 is scavenged with nitrogen gas, and then the etching is performed by a chemical supply pump (not shown). The liquid is supplied and stored (for example, 1000 cc). After supply, valve E1
And the valve S1 is closed. In this state, the sub pot 40
The inside is kept airtight, and the etching solution does not come into contact with the outside air.

The etching solution stored in the subpot 40 is temperature-controlled by the heater 44 and the stirrer 43 to an etching temperature (for example, 90 ° C.). Further, since the sub-pot 40 has a closed structure, the pressure inside the sub-pot 40 rises due to the temperature rise of the etching liquid, and the evaporation of the etching liquid is suppressed. Therefore, a stable composition can be maintained even after storage for a long period of time.

In the etching operation, the wafer 4 is set on the wafer base 8 of FIG. 2, the wafer ring 9 is placed, and the X-type packing 17 is operated by the vacuum pump 18 (see FIG. 1) to assemble the etching pot 5. Then, the etching base 8 is mounted on the etching base 6 by a loader (not shown) as shown in FIG. 1, and the etching head 7 is lowered to the opening on the upper surface of the etching pot 5.
The upper circumference of the etching pot 5 is hermetically sealed by the pot packing 31 (see FIG. 4) of the etching head 7.

In this state, the wafer 4 is moved to the wafer plate 1 by the heater 21 as preheating before etching.
1 to the etching temperature (for example, 90 ° C.). Then, the valves S2 and E2 are opened to supply nitrogen gas to the etching pot 5, and the inside of the etching pot 5 being heated is scavenged with nitrogen gas (all other valves are closed). As a result, the atmosphere is replaced with a nitrogen gas atmosphere.

When the temperature of the wafer 4 is raised to the etching temperature and the etching conditions such as the temperature are adjusted, a voltage is applied to the wafer 4 from the anodizing power supply 63 so that the wafer 4 is not etched even if it is exposed to the etching solution. To do. That is,
Preparations for electrochemically stopping the wafer 4 are made.

Thereafter, the valve S2 is closed and the sub pot 4
Stop driving of the 0-side heater 44 and the rotor 43a,
The valves C and S1 are opened, and nitrogen gas is supplied to the sub pot 40 from the air supply pipe 48. As a result, the pressure in the sub pot 40 rises, and the etching liquid in the pot 40 is supplied into the etching pot 5 from the supply / discharge liquid nozzle 38 through the communication pipe 60 by the pressure of nitrogen gas. At this time, since the voltage is applied to the wafer 4 from the anodizing power supply 63 during the inflow of the etching solution, the wafer 4 is not etched even if the etching solution is touched.

After the required amount of etching liquid is transferred from the sub pot 40 to the etching pot 5, the valve S1 is closed to stop the supply of nitrogen gas, the valves C and E2 are closed, and the etching pot 5 is sealed. Then, the stirring blade 32 of the etching head 7 is rotated.

The etching liquid in the etching pot 5 is
When the wafer 4 is heated by the heater 21 provided in the etching base 6 through the wafer 4 and the wafer 4 is heated to the etching temperature and the etching conditions are satisfied, the voltage application by the anodizing power supply device 63 is stopped to perform the etching. Start. Since the etching pot 5 has a closed structure like the sub pot 40 during the etching, the pressure inside the etching pot 5 rises due to the temperature rise of the etching liquid, and the evaporation of the etching liquid is suppressed. Therefore, a stable composition can be maintained.

During the etching, the etching liquid is stirred by the stirring blade 32 provided in the etching pot 5, and the diffusion plate 34 provided so as to face the wafer 4 uniformly stirs the entire surface of the wafer 4. The etching proceeds with a highly accurate in-plane distribution.

When the etching time obtained from the previously confirmed etching rate has elapsed, a voltage is again applied to the wafer 4 by the anodizing power supply device 63 to stop the etching.

Then, the stirring blade 32 of the etching head 7
Further, the heater 21 of the etching base 6 is stopped, and the liquid supply / drainage nozzle 38 provided in the etching head 7 is lowered to stop at a position where the distance from the surface of the wafer 4 becomes a predetermined value. A predetermined amount (for example, 30 cc) of etching liquid exists below the tip of the supply / drainage liquid nozzle 38. This liquid amount (for example, 30 cc) is the drainage amount (for example, 30 cc) of the etching liquid after etching in the etching pot 5 that is necessary for preventing contamination of the etching liquid, and the remaining amount (for example, 1000 cc-30 cc = 970 c).
c) is for reproduction.

After that, the valves C, E1 and S2 are opened, and nitrogen gas is supplied from the air supply port 36 on the etching pot 5 side. As a result, the etching pot 5
The internal pressure rises, and a part of the etching liquid after the etching is performed (for example, 1000 cc-30 cc = 970 c
c) is transferred from the supply / drainage liquid nozzle 38 through the communication pipe 60 into the sub pot 40 by the pressure of the nitrogen gas.

At this time, since the constant remaining amount (for example, 30 cc) is maintained even if the level of the etching solution is lowered, the wafer 4
Energization is maintained and an etching stop effect is secured. Then, when the etching liquid returns to the sub pot 40, the supply / drainage liquid nozzle 38 is returned to the original height, and the valves E1 and C are used.
And the valve S2 is closed. Furthermore, an etching liquid supply pump (not shown) supplies the same amount of the etching liquid left on the etching pot 5 side (for example, a drainage amount of 30 cc) to the sub-pot 40, and the liquid amount in the sub-pot 40 is set to the initial state. Make the liquid volume (for example, 1000 cc).

Again, in preparation for the etching work in the next cycle, the stored etching solution is heated and stirred while keeping the subpot 40 airtight so that the etching solution does not come into contact with the outside air. In this way, a part of the etching liquid after the etching is performed (for example, 970
cc) and a new etching solution (for example, 30 cc) are mixed, and the etching solution is regenerated.

On the other hand, in the etching pot 5, after returning the etching liquid to the sub pot 40, the valves E2, S3 and S4 are opened to open the etching pot 5
Inject pure water into it. Further, the stirring blade 32 provided on the etching head 7 is activated to dilute and wash the etching liquid. Further, by opening the valve S3, the ejector 62 operates, and the cleaning water can be efficiently drained, and the cleaning effect can be enhanced.

After thorough cleaning, the driving of the stirring blade 32 is stopped, the valve S4 and the valve E2 are closed to stop the water supply, and the ejector 62 is connected to the drain pipe (not shown) in the etching pot 5. Then, the cleaning water in the etching pot 5 is drained. Further, after draining the cleaning water in the etching pot 5 in this way, the valve S3 is closed and the valves E2 and S2 are opened to blow the inside of the pipe and the inside of the etching pot 5 to prevent the pure water from remaining. .

Subsequently, the etching operation is completed by performing the operation opposite to that at the start of etching, taking out the etching pot 5 from the etching unit 2, releasing the vacuum in the X-type packing 17 and taking out the wafer 4.

The etching of the next cycle is performed in the same procedure as described above. That is, the silicon wafer 4 is newly set in the etching pot 5, and the etching liquid adjusted to a predetermined temperature in the sub-pot 40 (the etching liquid after the regeneration treatment) is transferred to the etching pot 5 through the communication pipe 60. The silicon wafer 4 is etched in the etching pot 5, and the etching liquid in the etching pot 5 is transferred to the sub-pot 40 while leaving a predetermined amount (for example, 30 cc) in the etching pot 5, and a new etching liquid is predetermined in the sub-pot 40 (for example, 30 cc). In addition, the etching solution in the etching pot 5 after etching is discharged, and the wafer 4 is taken out. After that, this is repeated.

When such etching is repeated, the contamination concentration of the etching solution becomes a constant concentration and does not become higher than that. In other words, the cleanliness of the etching liquid remains in the etching pot 5 to the minimum necessary for one etching, and is drained by washing with water, and at the same time, the subpot 40 is replenished with a new liquid corresponding to the drained amount. With this configuration, the contamination of the etching solution does not progress beyond a certain level and the stable state can be always maintained without renewing the etching solution.

Here, the amount of the etching liquid left in the etching pot 5 after etching (30 cc was given as an example), that is, the amount of drainage liquid required to prevent contamination of the etching liquid in the etching liquid after etching is defined. This is the amount for keeping a small amount of liquid contamination and using a small amount of chemicals for a long period of time. By processing one wafer, the amount of contamination commensurate with Si dissolved in the etching liquid is drained from the etching liquid every time. By newly adding this amount, the amount of Si dissolved in the etching solution can be kept constant, and the cleanliness of the solution is stabilized for a long time.

In the conventional method of immersing in a water tank (see FIG. 9), the amount of Si dissolved increases in proportion to the number of processed wafers, and eventually the etching quality is adversely affected (the etching rate decreases, the etching surface becomes rough, etc.). ), So before that, we have adopted a method to update all the etching solution as a preventive maintenance. On the other hand, in the present embodiment, since the concentration is stable when the amount of dissolved Si is slightly increased from the state of the new liquid and the concentration is kept constant for a long period of time, the same conditions can be set for each etching rate and quality each time.

As described above, the sub-pot 40 is prepared separately from the etching pot 5, and the etching pot 5 and the sub-pot 40 are connected by the communication pipe 60.
Since a part of the etching liquid after etching at 0 was mixed with a new etching liquid and a regeneration treatment was performed to return it to the etching pot 5, the etching liquid is repeatedly used and the deterioration of the etching liquid quality is suppressed. It is possible to effectively use the etching solution while doing so. Further, since the etching solution is transferred without a pump by pressurizing the inside of both pots (containers) 5 and 40 with nitrogen gas (inert gas), the solution comes into contact with air. It is possible to avoid contamination of the liquid with air.
In this way, a resource-saving surface treatment device that has never existed can be achieved by controlling the amount of liquid to a minimum and by circulating the etching liquid without touching the atmosphere that decomposes or contaminates liquid such as air. You can

Further, by updating the etching solution little by little for each processing, there is an effect that the contamination of the etching solution can be minimized and the processing conditions can be stabilized for a long period of time. Further, since the etching method to be replenished for each etching can be selected by the management method optimum for storing the etching solution at room temperature or the like, the life of these solutions can be greatly extended.

Further, in the etching pot 5, the wafer 4 is placed on the bottom surface, and the surface to be etched is directed upward with respect to the etching liquid, so that the bubbles adhered during the supply of the etching liquid and the reaction gas generated during the etching. Can be easily removed, and unprocessed chips and defective shapes due to these bubbles can be eliminated. In addition, since the processing liquid can be processed in a small amount (internal volume of the etching pot), significant resource saving can be realized, and the etching pot 5 to the wafer 4 can be realized.
It is possible to continuously carry out washing with water on the spot without taking out the wafer, and it is also possible to reduce the thickness variation in the wafer surface caused by the reaction progressing during the transfer as in the conventional case. Further, the etching solution is kept at the etching temperature in the etching pot 5 which is kept airtight during the etching and in the subpot 40 during the non-etching, and is always isolated from the outside air by the nitrogen gas (inert gas). Therefore, even under a high temperature condition, the decomposition and evaporation are small and the etching conditions can be kept stable.

Further, since the liquid contact part is limited to the etching pot 5 and the sub pot 40, the etching pot 5
Even if the contamination due to the handling of occurs on the outer surface of the etching pot 5, the etching liquid is not contaminated at all,
Work can be done safely.

Further, since the etching in the etching pot 5 and the regeneration treatment in the sub-pot 40 are performed in the pots 5 and 40 having an airtight structure, the composition change of the etching solution can be prevented. Further, the etching pot 5 serves as a wafer jig, and the wafer is detachably supported, which is advantageous. Further, in the etching pot 5, a heater 2 that preheats the lower side of the wafer before etching
Since No. 1 is provided, it is preferable. Further, the electrodes 34 and 11 are arranged in the etching pot 5 so as to stop the wafer electrochemically, which is preferable.

Although the electrochemical stop etching mechanism (control of the start / stop of etching by the anodizing power supply device 63) is used in the above-described embodiment, this function is an auxiliary function and is provided as necessary. Just do it.

Further, the heater 21 is used for heating the etching liquid in the etching pot 5. This is effective for preheating the etching pot 5, and at the same time, the highest temperature is on the wafer surface. Therefore, it is very effective in keeping the stability of the liquid having high thermal decomposability for a long period of time. However, in the case of using a processing liquid that is not thermally decomposable or causes no problem, a heater may be arranged in the etching pot 5 to directly heat the liquid. Further, by using the heaters inside and outside the pot together, higher etching quality (in-plane etching amount distribution) can be obtained.

A magnetic coupling type stirring mechanism 43 was used for stirring the liquid in the sub pot 40.
The structure takes into consideration the fact that it works well for sealing, but when contamination by foreign matter in the etching solution is a problem, a stirring method with a shaft (impeller type) similar to the etching head
May be

Needless to say, the same effect can be obtained by heating the sub-pot 40 by the internal heater. The Bernoulli type (fluid driven type) ejector 62 is used to increase the drainage speed, but it may be omitted or other means may be used in consideration of the washing time.

Further, although the etching liquid was transferred from the etching pot 5 to the sub-pot 40 and the etching liquid was transferred from the sub-pot 40 to the etching pot 5 through the communication pipe 60 of FIG. 1, the etching pot 5 was moved to the sub-pot 40. There may be provided a communicating pipe for transporting the etching liquid and a communicating pipe for transporting the etching liquid from the sub pot 40 to the etching pot 5.

This embodiment has been described with respect to Si etching. However, the present invention can be applied to a wafer surface treatment process using a treatment liquid such as gold plating which is expensive and has a problem of liquid contamination. Needless to say.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram showing an etching apparatus of an embodiment.

FIG. 2 is an enlarged sectional view of an etching pot.

FIG. 3 is an enlarged cross-sectional view of an etching base.

FIG. 4 is an enlarged sectional view of an etching head.

FIG. 5 is an enlarged cross-sectional view of an etching liquid management unit.

FIG. 6 is a view showing a wafer.

FIG. 7 is a view showing a masking jig.

FIG. 8 is a diagram showing an acceleration sensor.

FIG. 9 is a process drawing for explaining an etching process.

FIG. 10 is a diagram showing a pressure sensor.

[Explanation of symbols]

2 ... Etching unit, 3 ... Etching solution management unit, 4 ... Silicon wafer, 5 ... Etching pot, 11
... Wafer plate, 15 ... Seal packing, 21 ... Heater, 31 ... Pot packing, 34 ... Diffusion plate, 40 ...
Sub pot, 60 ... Communication pipe, 61 ... Communication pipe.

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Claims (9)

(57) [Claims] 1. A surface treatment tank in which a treatment liquid is filled inside, a semiconductor wafer is supported at a bottom portion in a state where an outer peripheral portion of the semiconductor wafer is sealed, and a surface to be treated of the semiconductor wafer is immersed in the treatment liquid, and a surface treatment is performed. After treatment, a mechanism for discharging a predetermined amount of the treatment liquid except a part thereof, a part of the treatment liquid after the surface treatment, and a predetermined amount of a new treatment liquid are mixed to form a treatment liquid. Regeneration treatment tank for regeneration treatment, and a treatment after performing a regeneration treatment in the regeneration treatment tank while transferring a part of the treatment liquid after the surface treatment from the surface treatment tank to the regeneration treatment tank A surface treatment apparatus, comprising: a communication pipe for transferring the liquid from the regeneration treatment tank to the surface treatment tank. 2. The surface treatment apparatus according to claim 1, wherein the volume of the treatment liquid in the regeneration treatment tank is not less than the volume of the treatment liquid in the surface treatment tank. 3. A surface treatment tank and a surface treatment apparatus according to reproduction processing tank to claim 1 or 2, characterized in that a gas-tight structure. 4. The surface treatment apparatus according to claim 3, wherein the treatment liquid is transferred between the tanks by pressure-feeding the treatment liquid using a gas that does not contaminate the treatment liquid. 5. The surface treatment apparatus according to claim 3, wherein the inside of the bath is scavenged with a gas that does not contaminate the treatment liquid. 6. A wafer is detachably supported in the surface treatment bath, according to any one of claims 1 to 5.
The surface treatment apparatus as described in 1 above. 7. A surface treatment tank, one of the claim 1-6, characterized in that a means for preheating before surface treatment
The surface treatment apparatus as described in 1 above. 8. The surface treatment bath is provided with means for electrochemically stopping the wafer.
Surface treatment apparatus according to any one of to 7. 9. The surface treatment apparatus according to claim 7, wherein the preheating means heats from the lower surface side of the wafer.