JP2003338486A - Treating device and manufacturing method of semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a treating device which facilitates automation of changing the old phosphoric acid to new phosphoric acid, when its reproducing treatment has exceeded an upper limit, and which reduces impurities in the phosphoric acid or maintains the same at a given level. <P>SOLUTION: The treating device is provided with an etching tank 3 with an overflow section 3a for effecting the etching treatment of a semiconductor wafer 1 with hot phosphoric acid; a route section 5 of circulation and filtration which guides the phosphoric acid, overflowed into the overflow section 3a, to the outside of the etching tank 3 and returning the same into the etching tank 3 after filtrating, heating and adding pure water; a phosphoric acid reproducing device 6 for recovering the phosphoric acid which has finished the etching treatment and effecting heating treatment, by adding the phosphoric acid and hydrofluoric acid; a supplementing pipe 140a for supplementing the phosphoric acid, reproduced in the phosphoric acid reproducing device 6, into the etching tank 3; and an interchanging means for interchanging fresh phosphoric acid for the phosphoric acid in the etching tank 3, based on the number of times of the reproducing treatment. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a silicon nitride film (hereinafter, abbreviated as "nitride film") such as a semiconductor wafer (for example, a silicon wafer, hereinafter referred to as "wafer") with hot phosphoric acid (hereinafter, referred to as "nitride film"). The present invention relates to a processing apparatus that performs etching processing with "phosphoric acid" (sometimes abbreviated as "phosphoric acid"), and more particularly to a processing apparatus having a regenerating unit that recovers and reuses phosphoric acid that has contributed to etching processing.

[0002]

2. Description of the Related Art In wafer processing in semiconductor manufacturing or the like, a fine nitride film pattern may be formed on a wafer by etching. Although dry etching is mainly used in this etching, the formed nitride film is used as an oxidation mask to selectively form the oxide film, and the nitride film and the oxide film are removed by etching when the unnecessary nitride film mask is removed. The method of treating with hot phosphoric acid having a large selection ratio is still widely used today. In this wafer processing, if the etching is performed under the condition that the etching selection ratio of the nitride film and the oxide film is large, the nitride film of the wafer reacts with water to decompose into silicon oxide and ammonia, so that the etching is appropriately performed. In this reaction, phosphoric acid acts as a catalyst, and it is known that it can be used as a catalyst permanently by simply supplying water without being consumed, and efficient etching is possible.

[0003]

However, in actual wafer processing, in order to increase the etching selection ratio, the decomposed silicon oxide must be used in a state of being dissolved in hot phosphoric acid at a high concentration. However, when used under these conditions, the amount of dissolution reaches the saturated amount of dissolution and the silicon oxide is deposited as fine particles, which become fine particles to contaminate the wafer or re-etch the etching solution. It causes various obstacles such as clogging the circulating filtration filter for utilization. Therefore, before the dissolved amount of silicon oxide reaches the saturated dissolved amount, for example, the etching solution must be replaced with new phosphoric acid or the concentration of silicon oxide in phosphoric acid must be lowered. Phosphoric acid containing a large amount of silicon oxide cannot be used as an etching solution and must be disposed of as a waste solution, which may adversely affect the environment.

The etching rate of the nitride film mask is
If the phosphoric acid temperature is constant, it is constant regardless of the silicon oxide concentration, but the etching rate of the oxide film is inversely proportional to the silicon oxide concentration in phosphoric acid, and decreases as the silicon oxide concentration increases. As described above, the etching selection ratio between the nitride film and the oxide film changes depending on the silicon oxide film concentration, which causes variations in the oxide film thickness between processing lots, resulting in deterioration in quality. Therefore, it is necessary to increase the design of the wafer processing apparatus used and the processing margin by that amount, but the allowable margin is becoming smaller with the progress of miniaturization and high integration of IC. From such a background, it is desired to realize a wafer processing apparatus having a large selection ratio, a small variation among processing lots, and a phosphoric acid waste liquid which is not discharged.

In view of the above circumstances, the applicants of the present invention have been aware of the above-mentioned problems.
We have developed a wafer processing apparatus structure and a recycling method such as -293479 and JP-A-9-45660. The present invention is a further improvement of them, and in particular, the regeneration treatment facilitates the automation of exchanging phosphoric acid exceeding the upper limit with fresh phosphoric acid, and enables impurities in phosphoric acid to be reduced or kept constant. Is intended. Then, the etching selectivity between the nitride film and the oxide film is kept high, and the nitride film can be etched with phosphoric acid having the same selectivity.

[0006]

A processing apparatus according to the present invention introduces an etching tank with an overflow portion for etching a semiconductor wafer with hot phosphoric acid and a phosphoric acid overflowing the overflow portion to the outside of the etching tank. A circulation filtration passage part for returning filtration and heating and pure water to the inside of the etching tank, and a regeneration treatment for recovering phosphoric acid subjected to the etching treatment and adding hydrofluoric acid to the phosphoric acid for heat treatment are performed. In a wafer processing apparatus provided with a phosphoric acid regenerator and a replenishing pipe for replenishing the phosphoric acid regenerated by the phosphoric acid regenerator to the etching tank, based on the number of times the regenerating process is performed,
It has means for exchanging phosphoric acid in the etching bath with fresh phosphoric acid.

According to the treatment apparatus of the present invention, the phosphoric acid which has been subjected to the regeneration treatment a predetermined number of times is exchanged for new phosphoric acid, so that it is possible to prevent the increase of particles and the like in the phosphoric acid. The processing apparatus of the present invention can have the following aspects.

(A) In the processing apparatus of the present invention, the phosphoric acid regenerator comprises a receiving tank for temporarily containing the recovered phosphoric acid, and a processing tank for heating the phosphoric acid introduced from the receiving tank by adding hydrofluoric acid. And a storage tank for temporarily storing the phosphoric acid regenerated in the processing tank, wherein the processing tank cools and liquefies the vapor evaporated from the processing tank, and the storage tank is liquefied by the cooler. It is possible to have a constant temperature bath for adjusting the liquid to a constant temperature, and a measuring unit including a fluorine measuring instrument for measuring the fluorine concentration in the liquid adjusted in the constant temperature bath.

(B) In the treatment apparatus of the present invention, the circulation filtration route section has a branch pipe before the filtration section for filtering phosphoric acid, and the phosphoric acid is supplied in accordance with the circulating fluid pressure of phosphoric acid flowing to the filtration section. A means for controlling the amount of phosphoric acid introduced to the regenerator side can be provided.

(C) In the treatment apparatus of the present invention, the treatment tank has a circulation path for circulating the phosphoric acid in the tank, and the circulation path can have a filtration section.

(D) In the processing apparatus of the present invention, the storage tank has a heating means for controlling the regenerated phosphoric acid introduced from the processing tank to a predetermined temperature, and the storage tank and the overflow. The flow section can be connected by the supply pipe.

(E) In the processing apparatus of the present invention, the storage tank has a heating means for controlling the regenerated phosphoric acid introduced from the processing tank to a predetermined temperature. The replenishment pipe can be connected to the filtration path portion.

(F) In the processing apparatus of the present invention, the heating means can be controlled by the timing of supplying the regenerated phosphoric acid from the storage tank to the etching tank.

(G) In the processing apparatus of the present invention, the storage tank may have a pure water supply means for supplying pure water to the regenerated phosphoric acid in the tank.

(H) In the processing apparatus of the present invention, the replenishment pipe has a path for sending the regenerated phosphoric acid taken out from the storage tank to the etching tank or the overflow portion, and a circulation path for returning it to the storage tank again. Can be configured to be switchable.

The processing apparatus of the present invention can be used in a method of manufacturing a semiconductor device.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings showing the embodiments. FIG. 1 is a block diagram mainly showing an etching tank and a circulation filtration path portion in the apparatus of the present invention, and FIG. 2 is a block diagram mainly showing a phosphoric acid regenerating apparatus in the apparatus. In the following description, each part of the device of the present invention will be described, and then an example of device operation will be described. (Device Structure) This wafer processing device has an etching unit 4
The circulating filtration path portion 5 and the phosphoric acid regeneration device 6 are mainly configured. The etching part 4 is a part for immersing a plurality of wafers 1 in a wafer cassette 2 in hot phosphoric acid (etching solution) to etch the nitride film of the wafers 1. The circulation filtration path portion 5 is a portion where the phosphoric acid overflowing from the etching tank 3 is returned to the etching tank 3 again through the steps of filtering, heating and adding pure water. The phosphoric acid regenerator 6 collects phosphoric acid directly from the etching tank 3 or by branching it from the circulation filtration passage portion 5, lowers the silicon oxide concentration in the recovered phosphoric acid, and reduces the silicon oxide concentration to a certain level that can be used in the etching solution. This is a portion where the phosphoric acid is regenerated and returned to the overflow portion 3a of the etching tank 3. a. Etching Unit In this etching unit 4, an automatic transfer robot (not shown), a belt conveyor, and the like are arranged together with the etching tank 3, and the wafer 1 is put into and taken out of the tank body of the etching tank 3 for etching. The etching bath 3 has a chamber body defined by an inner peripheral wall 30 and a bottom wall 31, and an overflow portion 3a for receiving phosphoric acid overflowing from the upper end of the inner peripheral wall 30 is formed on the outer periphery. The inner peripheral wall 30 and the bottom wall 31 are internally provided with surface heaters, which are heating elements (not shown). A mesh 32, which is a dispersion plate, is provided inside the bottom of the tank body, and the wafer cassette 2 is held on the mesh 32.

The liquid introducing / discharging structure is provided on the upper side of the overflow portion 3a and is a replenishing port 3 for replenishing phosphoric acid (mainly regenerated phosphoric acid).
3, a discharge port 34 provided on the bottom wall of the overflow portion 3a for discharging the overflowed phosphoric acid to the circulation filtration passage portion 5, and a phosphoric acid provided on the bottom wall 31 and treated by the circulation filtration passage portion 5 A supply port 35 to be introduced into the bath main body, and a discharge port 36 which is also provided on the bottom wall for exhausting the entire amount of phosphoric acid in the etching bath 3.
And are provided.

As a control system, a liquid level sensor 37 for measuring the liquid level of phosphoric acid in the etching bath 3, a temperature sensor 38 for detecting the liquid temperature of phosphoric acid in the bath main body, and a temperature detected by the temperature sensor 38 are used as a basis. And a heater controller 39 for controlling the above surface heater to maintain the phosphoric acid at a predetermined temperature.
And are provided. The liquid level sensor 37 detects the amount of phosphoric acid in the tank and transmits the detection result to the control circuit 300. b. Circulation filtration route unit The circulation filtration route unit 5 is provided with a pump 50 and a filter 51 which is a filtering unit. Outlet 3 of overflow 3a
The phosphoric acid discharged from No. 4 is supplied by the pump 50 to the supply port 35.
Is returned to the tank body of the etching tank 3 and is filtered by passing through the filter 51. The circulation filtration route section 5 includes a line heater 52, a temperature sensor 53, a heater controller 54, and a metering pump 5 for supplying pure water.
It is equipped with 5. The line heater 52 keeps the filtered phosphoric acid at a predetermined temperature and is controlled by a temperature sensor 53 and a heater controller 54. Then, the metering pump 55 adds a predetermined amount of pure water to the phosphoric acid heated to the constant temperature. That is, here, the etching solution discharged from the overflow portion 3a, that is, phosphoric acid, is filtered by the filter 51.
Then, after being heated to a constant temperature by the line heater 52, pure water is added by the metering pump 55 to adjust the phosphoric acid concentration so as to be kept constant and then returned into the tank body. c. Phosphoric Acid Regenerating Device The phosphoric acid regenerating device 6 is mainly composed of a receiving tank 70, a processing tank 100, and a storage tank 130. The phosphoric acid that has been subjected to the etching treatment is regenerated, and the regenerated phosphoric acid is fed to the etching unit 4. It is the point of supply.

A discharge pipe 60 is connected between the receiving tank 70 of the phosphoric acid regenerator 6 and the discharge port 36 of the etching tank 3. The discharge pipe 60 is provided with an automatic valve 61, and by opening the automatic valve 61, phosphoric acid in the tank is discharged. A waste pipe 62 is branched from the discharge pipe 60. The waste pipe 62 is provided with an automatic valve 63, and when the automatic valve 63 is open, the phosphoric acid in the etching tank 3 is discarded.

Further, a branch pipe 64 is provided between the pump 50 and the filter 51 of the circulation filtration route section 5. The branch pipe 64 is provided with a pressure gauge 65, a needle valve 66 and an automatic valve 67. Here, the pressure gauge 65
Measures the fluid pressure (circulating fluid pressure or filtration pressure) in front of the piping portion between the pump 50 and the filter 51, that is, the filter 51. The needle valve 66 is a flow rate adjusting valve, and by appropriately adjusting the valve opening degree of the needle valve 66,
The flow rate of phosphoric acid branched from the branch pipe 64 is automatically controlled in accordance with the circulating fluid pressure. The automatic valve 67 is an open / close valve. Then, when the automatic valve 67 is open, the phosphoric acid branched from the branch pipe 64 is collected in the receiving tank 70.

The receiving tank 70 has a plurality of liquid level sensors 71 and constantly measures the amount of recovery. The measured data is transmitted to the control circuit 300 described later, and the control circuit 30
0 controls the opening and closing of the automatic valve 101 based on the recovery amount. That is, when the amount of phosphoric acid in the receiving tank 70 reaches a predetermined amount, the automatic valve 101 is opened, and phosphoric acid is introduced into the processing tank 100 through the bottom outlet 72.

The processing tank 100 is constructed in combination with the measuring section 7. The processing tank 100 includes a liquid level sensor 102, a surface heater 103, a surface heater 104, etc., and a temperature sensor 10.
5 and a heater controller 106 are provided.
The phosphoric acid in the bath is detected by the heater controller 106 based on the temperature detected by the temperature sensor 105.
It is adjusted by controlling 4 etc. Also, processing tank 1
Reference numeral 00 denotes a metering pump 107 which is pure water supply means for adding pure water into the tank, a replenishment pipe 108 in the tank, and a chemical liquid supply means for supplying a necessary amount of HF (hydrofluoric acid, that is, hydrogen fluoride). An HF tank 109 and a metering pump 110 are provided.

As the structure for introducing and discharging the liquid, the treatment tank 10 is used.
At the upper part of 0, a supply port 112 for supplying HF, a supply port 114 for introducing phosphoric acid from the receiving tank 70, and a vapor outlet 1 for taking out vapor necessary for the measuring unit 7.
And 13 are provided. A discharge port 115 for discharging phosphoric acid is provided at the bottom of the processing tank 100.

The discharge port 115 is provided with a filtration pipe 116, and the filtration pipe 116 is provided with an automatic valve 117, a pump 118, a filter 119 as a filtration section, and a heater 120. That is, the phosphoric acid discharged from the discharge port 115 is supplied to the supply port 11 by the pump 118.
2 is returned to the processing tank 100, and the filter 119
It is filtered by passing through and is heated by the heater 120. A branch pipe 121 is provided in the filtration pipe 116. The branch pipe 121 is provided with an automatic valve 122, and the phosphoric acid that has been regenerated is supplied to the branch valve 121 through the automatic valve 122.
It is discharged to the storage tank 130.

In this way, the filter 1 is attached to the filtration pipe 116.
By providing 19, foreign particles and particles in the regenerated phosphoric acid can be removed.

The measuring section 7 is a section for detecting the current concentration of hydrofluoric acid added to the phosphoric acid in the treatment tank 100 for regeneration and determining the progress and end point of regeneration. In this embodiment, a cooler 200 for cooling the vapor in the processing bath 100, a constant temperature bath 201 including a spiral tube for adjusting the liquid cooled here to a constant temperature and its temperature controller 202, and a liquid from the constant temperature bath 201 The heat-retaining container 203 that receives the heat and the conductivity sensor 204 that measures the conductivity of the liquid in the heat-retaining container 203 in order to calculate the fluorine concentration of phosphoric acid in the processing tank 100.
And a conductivity meter 205 having Since the heat insulation container 203 here uses the conductivity sensor 204, a container having a certain depth is used. Further, the concentration of fluorine in the phosphoric acid in the processing bath 100 is based on the conductivity data measured by the conductivity meter 205 and is a control circuit (microcomputer or the like) 300 which is the main control means of the apparatus.
Is calculated and calculated. The control circuit 300 is
The amount of hydrofluoric acid and pure water added according to the amount of phosphoric acid in the treatment tank 100 is calculated, and the metering pump 1 is used so as to satisfy each calculated amount.
10, 107, notifies the end of regeneration when the fluorine concentration falls below a predetermined value, controls the above-mentioned automatic valves, needle valves, metering pumps, etc. of each part as necessary, and controls each part. The entire wafer processing apparatus is controlled by exchanging necessary signals with a heater controller or the like.

The storage tank 130 stores the phosphoric acid regenerated in the processing tank 100 in a batch manner through the branch pipe 121, and supplies the regenerated phosphoric acid to the overflow portion 3a through the replenishment pipe 140a. is there.

The storage tank 130 includes a surface heater 131, a surface heater 132, a liquid level sensor 133, and a temperature sensor 13.
4 and a heater controller 135. The surface heater 131 and the surface heater 132 heat the stored regenerated phosphoric acid to a predetermined temperature, the temperature sensor 134 detects the temperature of the phosphoric acid in the bath, and the heater controller 135 uses the surface heater based on the detected temperature. 131 and 132 are controlled.
Further, the storage tank 130 can be provided with a metering pump 136 which is a pure water supply means for adding pure water into the tank, and a supply pipe 137 inside the tank.

Conventionally, phosphoric acid, which has been subjected to the regeneration treatment, is introduced into the etching tank 3 without adjusting the concentration and temperature. Therefore, it is necessary to adjust the concentration and temperature after being introduced into the etching tank 3. However, there is a problem that the stop time of the device becomes long. However, according to the present invention, since the storage tank 130 is provided with the heating means and the pure water supply means, the temperature and the concentration of the storage tank 130 are set to the conditions suitable for the process in advance before being introduced into the etching tank 3. Adjusted. The phosphoric acid thus adjusted can be processed immediately after being supplied to the etching bath 3.
The down time of the device can be shortened.

The heating means is controlled by the etching tank 3
It can be performed at the timing of supplying the regenerated phosphoric acid to. For example, when the heating means is used only immediately before supplying the regenerated phosphoric acid to the etching tank 3, unnecessary power consumption can be prevented.

The storage tank 130 and the overflow portion 3a are connected by a replenishment pipe 140a provided with an automatic valve 143 and a needle valve 144 on the overflow portion 3a side. Supply pipe 140a
The circulation pipe 14 branched upstream from the automatic valve 143.
0b is provided. That is, when the automatic valve 143 is closed, phosphoric acid is supplied to the supply pipe 140a and the supply pipe 140b.
It is returned to the storage tank 130 via and is circulated. Then, based on the measurement result of the liquid level sensor 37 of the etching tank 3 described above, signals are transmitted from the control circuit 300 to the pump 141 and the needle valve 144, whereby the regenerated phosphoric acid in the storage tank 130 is It is supplied to the overflow portion 3a. Also,
The fresh liquid supply unit 8 is provided in the supply pipe 140a. Specifically, in the supply pipe 140 a, a new liquid supply pipe 150 is provided between the supply port 33 of the etching tank 3 and the needle valve 144, and the new liquid supply pipe 150
Connects the supply pipe 140a and a new phosphoric acid tank 153. The fresh solution supply pipe 150 is provided with a pump 152 and an automatic valve 151, and new phosphoric acid solution is supplied through the fresh solution supply pipe 150 as needed. (Device Operation) Next, an example of the operation or operation of the wafer processing device described above will be described by way of an example in which batch processing is performed.

First, when the wafer 1 coated with the nitride film is placed in the etching bath 3 filled with heated phosphoric acid in the state of being housed in the wafer cassette 2, the nitride film on the wafer 1 is removed by the hot phosphoric acid. Etched. In this process, hot phosphoric acid overflowing from the main body of the etching tank 3 is collected in the overflow portion 3a and is discharged from the discharge port 34 to the circulation filtration path portion 5 and is sent to the filter 51 side by the pump 50. The phosphoric acid that has passed through the filter 51 has a desired temperature at the line heater 52 (for example, the temperature immediately before the boiling point of phosphoric acid).
The temperature is increased to 55 ° C and the measuring pump 55
A predetermined amount of deionized water is added through the supply port 35 and is sent from the supply port 35 into the main body of the etching tank 3 for circulation. In this way, the phosphoric acid is circulated in the etching bath 3, so that the wafer 1
The nitride film is properly etched.

In this etching process, the automatic valve 61 is opened by a signal from the control circuit 300 when the wafer cassette 2 is unloaded from the etching tank 3 after a predetermined number of batches of etching processing. The total amount of phosphoric acid in the tank is discharged from the discharge port 36 and collected in the receiving tank 70 via the discharge pipe 60. The control circuit 300 closes the automatic valve 61 and then controls the automatic valve 14 of the supply pipe 140a.
3 is opened, and regenerated phosphoric acid in a storage tank 130 described later is supplied to the etching tank 3. The liquid level sensor 37 of the etching tank 3 measures the amount of phosphoric acid supplied into the tank, and the automatic valve 143 is measured according to the measurement result of the liquid level sensor 37.
Is closed. At this time, if the amount of the regenerated phosphoric acid supplied is less than the predetermined amount in the etching tank 3, the automatic valve 151 of the new solution supply unit 8 is opened and new phosphoric acid is supplied via the new solution supply pipe 150. Is supplied.

When exchanging the phosphoric acid which has been subjected to the etching treatment as described above, if the number of times the phosphoric acid in the etching tank 3 is regenerated exceeds the upper limit, the control circuit 300 discards the branch from the discharge pipe 60. The automatic valve 63 provided in the pipe 62 is opened. The phosphoric acid in the tank is discharged from the outlet 36
And is discarded through the waste pipe 62. After the phosphoric acid in the tank is discarded, the control circuit 300 sets the automatic valve 61
And the automatic valve 63 is closed, and the automatic valve 151 of the new liquid supply unit 8 is opened. Fresh phosphoric acid is supplied to the etching bath 3 through a new liquid supply pipe 150. The liquid level sensor 37 of the etching tank 3 measures the supply amount of new phosphoric acid, and the automatic valve 15 is measured based on the measurement result of the liquid level sensor 37.
1 is in the closed state.

Further, in the circulation filtration route portion 5, in order to maintain the concentration of phosphoric acid suitable for the process treatment until the next exchange of the etching solution during the etching treatment, phosphoric acid having a high silicon oxide concentration is maintained. A branch pipe 64 for discharging a part of the above is provided. The branch pipe 64 is provided with a pressure gauge 65, and the pressure gauge 65 measures the circulating fluid pressure in front of the filter 51. When the concentration of silicon oxide in phosphoric acid increases, the silicon oxide deposition on the filter 51 increases and the circulating fluid pressure increases. That is, by measuring the circulating fluid pressure, the silicon oxide concentration of phosphoric acid can be predicted. Pressure value measured by pressure gauge 65 (circulating fluid pressure)
Is transmitted to the control circuit 300, and the control circuit 300 opens the automatic valve 66 if the measurement result is equal to or more than a predetermined value, and a part of phosphoric acid flowing through the circulation filtration path unit 5 is branched. It is collected in the receiving tank 70 via 64.

In the etching bath 3, the liquid level sensor 37 constantly measures the liquid level in the bath, and the result is transmitted to the control circuit 300. As described above, the circulation filtration path unit 5
When a part of the phosphoric acid is recovered from the etching tank 3 and the phosphoric acid in the etching tank 3 decreases, the control circuit 300 opens the automatic valve 143 of the supply pipe 140a to replenish the phosphoric acid having a low silicon oxide concentration.

In this case, since the regenerated phosphoric acid in the storage tank 130 is regenerated in the processing tank 100 and has a low silicon oxide concentration, the silicon oxide concentration in the phosphoric acid in the etching tank 3 is also maintained at a low value accordingly. to enable. Further, in the circulation filtration passage portion 5, the phosphoric acid having a low silicon oxide concentration is sent from the pump 50 to the filter 51 side, so that the deposited silicon oxide of the filter 51 is redissolved and removed. The advantage is that when the phosphoric acid has a low silicon oxide concentration, the deposited silicon oxide of the filter 51 is redissolved and the filter 51 can be used for a long period of time.

In this way, by discarding phosphoric acid whose number of regeneration treatments exceeds the upper limit and replacing it with new phosphoric acid,
It is possible to exchange phosphoric acid that has accumulated foreign substances, contaminants, etc., that were brought in when the wafer was loaded. Further, in the etching process until the next exchange of phosphoric acid, a part of phosphoric acid having a silicon oxide concentration higher than a predetermined concentration is discharged and phosphoric acid having a low silicon oxide concentration is replenished, so The concentration can be maintained in an optimal state.

In the receiving tank 70, the data measured by the liquid level sensor 71 is transmitted to the control circuit 300, and the control circuit 300
Controls the automatic valve 101 based on the measured data.
That is, when the phosphoric acid in the receiving tank 70 reaches a predetermined amount, the automatic valve 101 is opened and the phosphoric acid in the receiving tank 70 is collected in the processing tank 100.

The phosphoric acid recovered in the processing tank 100 is discharged from the discharge port 115 and circulated through the filtration pipe 116 during the regeneration process. A filter 119 is provided in this circulation path to remove impurities in phosphoric acid.

As described above, the phosphoric acid in the processing tank 100 is circulated through the filtering pipe 116 and passes through the filter 119 which is a filtering section, so that impurities and particles in the phosphoric acid can be removed.

In this regeneration process, the HF tank 10
An appropriate amount of hydrofluoric acid of 9 is supplied into the processing tank 100 by the measuring pump 110, and an appropriate amount of pure water is supplied into the processing tank 100 by the measuring pump 107 through the supply pipe 108. The amount of hydrofluoric acid and pure water supplied is, for example,
See the relevant parts of JP-A-11-293479. Then, in this regeneration processing, the surface heaters 103, 10
4 is controlled to raise the temperature of the liquid in the processing bath 100, and the vaporized vapor is taken out from the vapor outlet 113 through the cooler 2
00 to cool and return to liquid. This liquid passes through the spiral tube in the constant temperature bath 201 and is poured into the heat retaining container 203 while being adjusted to a constant temperature. In addition, heat insulation container 2
A new liquid is always flowed into 03 to prevent old liquid from being accumulated. The liquid flowing out from the heat insulation container 203 is subjected to necessary processing.

Subsequently, the conductivity of the liquid in the heat retaining container 203 is measured by the conductivity meter 205 (conductivity sensor 204), and the measured data is stored in the storage section of the control circuit 300.
In the control circuit 300, the data is arithmetically processed to calculate the fluorine concentration, the time when the fluorine concentration becomes a conductivity corresponding to a desired value is determined, and the silicon oxide concentration in the phosphoric acid in the processing bath 100 is set to a predetermined value. Determine when it is lower. In addition,
For the phosphoric acid in the processing bath 100, the concentration of silicon oxide in phosphoric acid is reduced by adding the above-mentioned hydrofluoric acid and adding pure water, and this phosphoric acid has a low silicon oxide concentration that can be used for etching the nitride film of the wafer 1. Then, in response to a command from the control circuit 300, the automatic valve 122 is opened and the automatic valve 122 is discharged to the storage tank 130. The amount of phosphoric acid in the storage tank 130 is measured by the liquid level sensor 133, and the opening time of the automatic valve 122 is controlled by the detection result.

In this regeneration process, the number of times each etching solution is regenerated is stored in the control circuit 300. As described above, the phosphoric acid having the number of times of regeneration exceeding the upper limit is introduced into the etching tank 3 and is discarded after the etching process of a predetermined number of batches is completed. The number of times of regeneration is measured by, for example, introducing the liquid from the receiving tank 70 into the processing tank 100, the number of times the automatic valve 101 is opened, or introducing phosphoric acid after regeneration into the storage tank 130. Automatic valve 12
This is done by measuring the number of times 2 has been opened.

The phosphoric acid in the storage tank 130 is supplied to the surface heater 13.
1,132 keeps a predetermined temperature (for example, a temperature just before the boiling point), and when it is replenished to the overflow portion 3a, the temperature of phosphoric acid in the circulation filtration passage portion 5 and the main body of the etching tank 3 does not decrease. Is processed. And the overflow portion 3a
When replenishing the storage tank 1, the automatic valve 143 is opened and the storage tank 1
The phosphoric acid in 30 is supplied through the pump 141, the automatic valve 143, and the needle valve 144. The phosphoric acid in the storage tank 130 is normally supplied from the replenishment pipe 140a to the needle valve 142.
And is circulated through the circulation pipe 140b. The needle valve 142 is controlled so that the valve opening is minimized only when the overflow portion 3a is replenished. This is the storage tank 130
This is to keep the phosphoric acid temperature in the inside as constant as possible.

The phosphoric acid in the storage tank 130 can be heated in addition to being heated as described above, for example, in accordance with the timing of supplying the liquid to the etching tank 3. In this method, in particular, when the etching treatment is performed a predetermined number of times in the etching tank 3 and the total amount of the etching liquid is exchanged, the timing of supplying the etching liquid to the etching tank 3 is known in advance. It is possible to prevent unnecessary heating and reduce power consumption.

Further, in the storage tank 130, the measuring pump 13
6, the concentration and temperature of phosphoric acid in the tank can be adjusted by adding pure water through 6 and the replenishment pipe 137, and the same state as the phosphoric acid used for the process can be obtained. As a result, the process treatment can be started immediately after being supplied to the etching bath 3.

For the phosphoric acid in the storage tank 130 whose concentration and temperature have been adjusted as described above, the automatic valve 143 is opened based on the measurement result of the liquid level sensor 37, and the phosphoric acid in the storage tank 130 is pumped. 141, automatic valve 143 and needle valve 1
Supplied via 44. The phosphoric acid in the storage tank 130 is supplied from the supply pipe 140a to the needle valve 142 and the circulation pipe 140b when the automatic valve 143 is closed.
Is circulated through. The needle valve 142 is controlled so that the valve opening is minimized only when the overflow portion 3a is replenished. This is to keep the phosphoric acid temperature in the storage tank 130 as constant as possible.

The replenishment pipe 140a is connected to the storage tank 130.
If the phosphoric acid in the inside is insufficient or cannot be supplied to the etching tank 3 because of the inability to adjust the temperature or the concentration, the automatic valve 151 of the new liquid supply pipe 150 of the new liquid supply unit 8 It is opened and new phosphoric acid solution is supplied to the etching bath 3.

As described above, in this structure, the processing tank 10 is
The fluorine concentration in phosphoric acid in 0 is measured without being affected by temperature changes and carbon dioxide in the air.
The concentration of fluorine remaining in the phosphoric acid regenerated at 00 can be measured with high accuracy, and the concentration of silicon oxide in phosphoric acid can be estimated with high accuracy from the measured value of fluorine concentration. Further, in the phosphoric acid solution regenerator 6, the waste solution phosphoric acid can be suppressed as much as possible, and not only the cost reduction but also the adverse effect on the environment can be suppressed.

The present invention is not limited to the above embodiment, and various modifications and developments are possible within the scope of the gist of the present invention.
The following modes can be adopted. Note that FIG. 3 shows an example of the modification.

The regenerated phosphoric acid in the storage tank 130 may be supplied not to the overflow section 3a but to the circulation filtration path section 5 or the main body of the etching tank 3. This case will be described with reference to FIG. When supplying to the circulation filtration route section 5, as shown in FIG.
A branch replenishment pipe 160 can be provided in the. The branch replenishment pipe 160 can be connected to the upstream side of the filter 51 of the circulation filtration path unit 5 and has an automatic valve 161. When the automatic valve 161 is opened, the regenerated phosphoric acid is supplied via the branch supply pipe 160 to the front of the filter section (filter 51) of the circulation filtration path section 5. With such a structure, the supplied phosphoric acid passes through the filter 51 and the line heater 52 of the circulation filtration path portion 5 and the like, and is supplied to the etching tank 3 from the supply port 35 while adjusting the temperature and the concentration. Will be done. In addition, since it passes through the filter 51,
If the phosphoric acid after regeneration contains particles, there is an advantage that such particles can be removed.

When the capacity of the etching tank 3 is large, the processing tanks 100 may be provided in pairs, and the phosphoric acid recovered in the receiving tank 70 may be introduced into both processing tanks 100 in a switching manner to perform a regeneration process. .

A flow meter is provided in the discharge pipe 60 and the branch pipe 64 to measure the amount of recovered phosphoric acid, and the phosphoric acid regenerated or new phosphoric acid is supplied to the etching tank 3 based on the measured amount. Good.

In order to maintain the concentration of phosphoric acid suitable for the process treatment until the next etching solution exchange, in addition to the method of appropriately recovering phosphoric acid according to the circulation pressure of the circulation filtration section as described above, The following method can be used.

In order to carry out the etching process under appropriate conditions, when a part of the phosphoric acid is discharged from the circulation filtration path portion 5, the whole amount of phosphoric acid overflowed when the wafer cassette 2 is put into the etching tank 3 is directly received in the tank. 70 can be collected.
In this case, when the wafer cassette 2 is loaded into the etching tank 3, the control circuit 300 controls the automatic valve 67 of the branch pipe 64.
To open. As a result, the phosphoric acid overflowing the overflow portion 3a is directly recovered in the receiving tank 70 via the branch pipe 64,
It is possible to reliably discharge a part of phosphoric acid having a high silicon oxide concentration.

The pure water supplied to the circulation filtration path section 5 and the processing tank 100 can actually be supplied from the same pure water reservoir section through the illustrated pipes.

As a structure for discharging phosphoric acid from the etching tank 3, a mode in which the discharge port 36 is not provided in the bottom wall 31 will be described with reference to FIG. As shown in FIG. 3, a discharge pump 170 can be provided in the branch pipe 64. In this case, the bottom wall 31 of the etching bath 3
It is not necessary to provide the discharge port 36 of. When the phosphoric acid is discharged from the etching tank 3, the discharge pump 170 provided in the branch pipe 64 is operated. First, the phosphoric acid in the circulation filtration path portion 5 is passed through the backflow branch pipe 64 to receive the phosphoric acid. 70
Will be collected. Further, the phosphoric acid in the etching tank 3 is discharged from the supply port 35, flows back through the circulation filtration path portion 5, and is collected in the receiving tank 70 via the branch pipe 64. In this way, phosphoric acid in the etching bath 3 can be discharged.

The branch pipe 64 can be provided by branching the waste pipe 69. The waste pipe 69 is provided with an automatic valve 68. When the phosphoric acid whose number of regenerations has reached the upper limit is discarded, the automatic valve 67 of the branch pipe 64 is closed and the automatic valve 68 of the waste pipe 69 is opened, and the discharge pump 170 is operated to circulate the circulation filtration path. By backflowing the portion 5, the phosphoric acid in the etching tank 3 can be discarded.

When the discharge pump 170 is not used, the gravity drop method is used for collection, so that it takes time to collect the liquid, and there is a problem in that the arrangement of the apparatus is limited. As described above, by providing the discharge pump 170, the liquid recovery time can be shortened and the restrictions on the arrangement of the device can be reduced. Further, in the present embodiment, the supply port 35 and the discharge port 36 are provided in the bottom wall 31 of the etching tank 3. However, by providing the discharge pump in the branch pipe 64, the supply port 35 becomes the circulation filtration path part. 5 can serve as a supply port when supplying phosphoric acid and as a discharge port when discharging phosphoric acid in the etching bath 3. for that reason,
It is not necessary to newly provide the discharge port 36 in the etching tank 3.

Further, for example, as shown in FIGS. 1 and 2, even when the discharge port 36 is provided and the discharge pipe 60 is provided, the discharge pump is provided in the discharge pipe 60 to collect the liquid. The time can be shortened and the restrictions on the arrangement of the device can be reduced.

This discharge pump is provided in the branch pipe 64, and in addition to the pipe connecting the receiving tank 70 and the processing tank 100,
In addition, it can be used as a pipe used when inflowing phosphoric acid, such as a pipe connecting the processing tank 100 and the storage tank 130.

In the present embodiment, the case where the batch processing is performed has been described for the apparatus operation example, but it can also be used in the case of continuous processing.

As described above, in the wafer processing apparatus of the present invention, it is easy to automate the replacement of phosphoric acid whose regeneration processing exceeds the upper limit with new phosphoric acid, and, if necessary, to increase the temperature from the branch pipe. A part of phosphoric acid having a silicon oxide concentration is discharged. As a result, impurities of phosphoric acid can be reduced, the concentration can be maintained constant, and variations in wafer etching accuracy between lots can be suppressed.

[Brief description of drawings]

FIG. 1 is a configuration diagram mainly including an etching unit and a circulation filtration route unit of a processing apparatus according to the present embodiment.

FIG. 2 is a configuration diagram mainly including a phosphoric acid regenerating unit of the processing apparatus according to the present embodiment.

FIG. 3 is a configuration diagram mainly including an etching unit and a circulation filtration route unit of a processing apparatus according to a modified example of the present embodiment.

[Explanation of symbols]

1 Semiconductor wafer (wafer) 3 etching tank 3a Overflow part 4 Etching part 5 Circulation filtration route section 6 Phosphoric acid regeneration equipment 7 Measuring section 8 New liquid supply section 51 Filter (filter unit) 60 discharge pipe 64 branch piping 70 receiving tank 100 processing tanks 109 Hydrofluoric acid tank (HF tank) 116 Filtration piping 119 Filter (filter unit) 130 storage tank 140a Supply pipe 140b circulation piping 150 New liquid supply piping 200 cooler 201 Constant temperature bath (including spiral tube) 203 Insulated container 204 conductivity sensor 205 Conductivity meter (fluorine measuring instrument) 300 control circuit (control means)

Continued front page    (72) Inventor Naoto Kubota             Seiko, 3-3-3 Yamato, Suwa City, Nagano Prefecture             -In Epson Corporation (72) Inventor Akinori Shindo             Seiko, 3-3-3 Yamato, Suwa City, Nagano Prefecture             -In Epson Corporation (72) Inventor Nobuhiko Izuda             1-1-6 Kanda-Jinbocho, Chiyoda-ku, Tokyo               Within Nisso Engineering Co., Ltd. (72) Inventor Koji Ueda             1-1-6 Kanda-Jinbocho, Chiyoda-ku, Tokyo               Within Nisso Engineering Co., Ltd. F-term (reference) 5F043 AA35 BB23 EE40

Claims (10)

[Claims] 1. An etching tank with an overflow portion for etching a semiconductor wafer with hot phosphoric acid, and the phosphoric acid overflowing in the overflow portion is guided outside the etching tank to be filtered, heated, and added with pure water for etching. A circulation filtration route part returning to the inside of the tank, a phosphoric acid regenerator for recovering phosphoric acid subjected to the etching treatment, and a heating treatment by adding hydrofluoric acid to the phosphoric acid, and a regenerated by the phosphoric acid regenerator. A wafer processing apparatus comprising: a supply pipe for supplying the generated phosphoric acid to the etching tank, having means for exchanging the phosphoric acid in the etching tank with a new phosphoric acid based on the number of times of the regenerating process. , Processing equipment. 2. The phosphoric acid regenerator according to claim 1, wherein the recovered phosphoric acid is temporarily put into the receiving tank, a treatment tank is added with hydrofluoric acid to heat the phosphoric acid introduced from the receiving tank, and the treatment is performed. A storage tank for temporarily storing phosphoric acid regenerated in the tank, wherein the processing tank cools and liquefies the vapor evaporated from the inside of the processing tank; and a liquid liquefied by the cooler. A processing apparatus comprising: a constant temperature bath for adjusting the temperature to a constant temperature; and a measuring unit including a fluorine measuring unit for measuring the fluorine concentration in the liquid adjusted in the constant temperature bath. 3. The circulation filtration path section according to claim 1, wherein the circulation filtration path section has a branch pipe in front of the filtration section for filtering phosphoric acid, and phosphoric acid regeneration is performed according to the circulating fluid pressure of phosphoric acid flowing to the filtration section. A processing device having means for controlling the amount of phosphoric acid introduced to the device side. 4. The processing apparatus according to claim 2, wherein the processing tank has a circulation path for circulating the phosphoric acid in the tank, and the circulation path has a filtering section. 5. The storage tank according to any one of claims 2 to 4, wherein the storage tank has heating means for controlling the regenerated phosphoric acid introduced from the processing tank to a predetermined temperature,
The processing device, wherein the replenishment pipe is connected to the overflow portion. 6. The storage tank according to claim 2, wherein the storage tank has heating means for controlling the regenerated phosphoric acid introduced from the processing tank to a predetermined temperature,
A processing device, which is connected to the circulation filtration path portion by the supply pipe. 7. The processing apparatus according to claim 5, wherein the heating unit is controlled by the timing of supplying the regenerated phosphoric acid from the storage tank to the etching tank. 8. The processing apparatus according to claim 2, wherein the storage tank has a pure water supply unit that supplies pure water to the regenerated phosphoric acid in the tank. 9. The replenishment pipe according to any one of claims 2 to 8, wherein the replenishment pipe is a route for sending the regenerated phosphoric acid taken out from the storage tank to the etching tank or the overflow portion, and a circulation for returning it to the storage tank again. It is configured to be switchable with the route,
Processing equipment. 10. A method of manufacturing a semiconductor device, which uses the processing apparatus according to claim 1.