JP2003338487A - Treating device and manufacturing method of semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a treating device, easily controlling the surface of the phosphoric acid in an etching tank at a constant level. <P>SOLUTION: The treating device comprises an etching tank 3 with an overflow section 3a for effecting the etching treatment of a semiconductor wafer 1 with hot phosphoric acid; a circulating and filtrating route section 5 for guiding 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 adding filtration, heating and pure water; a phosphoric acid reproducing device 6 for applying a heating treatment on the phosphoric acid taken out of the circulation and filtration route section 5 by adding hydrofluoric acid; a supplementing pipeline 140a for supplementing the phosphoric acid, reproduced in the phosphoric acid reproducing device 6, into the etching tank 3; and a fresh solution supplying section 8 for supplying new phosphoric acid. <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 wafer processing apparatus that performs an etching process with "phosphoric acid" (abbreviated as "phosphoric acid"), and more particularly to a processing apparatus that has a recycling unit that recovers and reuses the phosphoric acid used in the etching process.

[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. The mainstream of this etching is dry etching, but an oxide film is selectively formed using the formed nitride film as a mask for oxidation, and a nitride film is used to remove the unnecessary nitride film mask. A method of using hot phosphoric acid, which has a large etching selection ratio of an oxide film, is used. 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. When used under this condition, the dissolved amount reaches the saturated dissolved amount and the silicon oxide is deposited as fine particles, which become fine particles to contaminate the wafer or reuse the etching solution. It causes various troubles such as clogging of the circulation filtration filter. 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 of the nitride film and the oxide film changes depending on the silicon oxide film concentration, so that the oxide film thickness varies between the processing lots, resulting in deterioration of 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, in an etching bath,
The purpose is to facilitate the control for keeping the liquid level of phosphoric acid constant.

[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. Filtering, heating and a circulation filtration route part which adds pure water and returns to the inside of the etching tank, and a phosphoric acid regenerator which performs hydrothermal treatment by adding hydrofluoric acid to phosphoric acid taken out from the circulation filtration route part through a branch pipe, A replenishment pipe for replenishing the etching tank with phosphoric acid regenerated by the phosphoric acid regenerator, and a new solution supply unit for supplying a new phosphoric acid solution to the etching tank in accordance with the amount of regenerated phosphoric acid in the phosphoric acid regenerator. ,including.

According to the processing apparatus of the present invention, when the phosphoric acid regenerated in the storage tank is insufficient when the phosphoric acid is supplied to the etching tank, new phosphoric acid is supplied to the etching tank from the new solution supply unit. Can be supplied. That is, phosphoric acid can be stably supplied to the etching tank regardless of the liquid amount and liquid state of the phosphoric acid regenerated in the phosphoric acid regenerator. The wafer processing apparatus of the present invention can have the following aspects.

(A) In the treatment apparatus of the present invention, the phosphoric acid regenerator adds a hydrofluoric acid to the phosphoric acid introduced from the receptive tank, and a receptive tank into which the phosphoric acid taken out from the circulation filtration passage is once put. A treatment tank for heating, and a storage tank for temporarily storing the phosphoric acid regenerated in the treatment tank, wherein the treatment tank cools and liquefies the vapor evaporated from the inside of the treatment tank; A constant temperature bath for adjusting the liquid liquefied by the cooler to a constant temperature, and a measuring unit including a fluorine measuring means for measuring the fluorine concentration in the liquid adjusted by the constant temperature bath,
Can be included.

(B) In the processing apparatus of the present invention, the branch pipe is provided in front of the filtration section of the circulation filtration path section and has means for causing phosphoric acid overflowing in the overflow section to flow into the receiving tank. be able to.

(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 may have a heating means for controlling the regenerated phosphoric acid introduced from the processing tank to a predetermined temperature, and further, the storage tank, The supply pipe can be connected to the overflow portion.

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

(F) In the processing apparatus of the present invention, the heating means is 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 include 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.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram mainly showing an etching tank and a circulation filtration route part in the wafer processing apparatus of the present invention, and FIG. 2 is a block diagram mainly showing a phosphoric acid reclaiming apparatus in the apparatus. In the following description, each part of the wafer processing apparatus of the present invention will be described, and then an operation example will be described. (Device Structure) This wafer processing device has an etching unit 4
The circulating filtration path portion 5 and the phosphoric acid regenerating device 6 are mainly configured. The etching unit 4 includes a plurality of wafers 1.
Is a portion where the nitride film of the wafer 1 is etched by being immersed in hot phosphoric acid (etching liquid) while being accommodated in the wafer cassette 2. 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 branches the phosphoric acid from the circulation filtration path unit 5 to reduce the silicon oxide concentration in the phosphoric acid, regenerates the phosphoric acid into usable phosphoric acid having a constant silicon oxide concentration, and overflows the etching tank 3. It is a place to return to the portion 3a. 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 structure for introducing and discharging the liquid has an overflow portion 3a.
A replenishment port 33 provided on the upper side of the replenishment unit for replenishing phosphoric acid (mainly regenerated phosphoric acid), and a discharge port 34 provided on the bottom wall of the overflow unit 3a for discharging the overflowed phosphoric acid to the circulation filtration route unit 5. Bottom wall 3
1 and a supply port 35 for introducing the phosphoric acid treated in the circulation filtration passage portion 5 into the tank main body.

As the control system, a plurality of liquid level sensors 36 for measuring the phosphoric acid liquid level in the overflow 3a, a temperature sensor 37 for detecting the phosphoric acid liquid temperature in the tank body, and a temperature detected by the temperature sensor 37 are used. A heater controller 38 for controlling the surface heater to maintain the phosphoric acid at a predetermined temperature is provided. b. Circulation filtration path section This circulation filtration path section 5 is provided with a pump 50 and a filter 51 as a filtering section. The phosphoric acid discharged from the discharge port 34 is returned from the supply port 35 to the tank main body of the etching tank 3 by the pump 50, and is filtered by passing through the filter 51. The circulation filtration path unit 5 is additionally provided with a line heater 52, a temperature sensor 53, a heater controller 54, and a metering pump 55 for supplying pure water. 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. And the metering pump 55
As a result, a predetermined amount of pure water is added to the phosphoric acid heated to the constant temperature. That is, here, with respect to the etching liquid discharged from the overflow portion 3a, that is, phosphoric acid, the phosphoric acid is first filtered by the filter 51. Next, the phosphoric acid is heated to a constant temperature by the line heater 52, and then the metering pump 55.
Then, pure water is added to adjust the phosphoric acid concentration so as to be kept constant, and the phosphoric acid concentration is returned into the tank body. c. Phosphoric Acid Regeneration Device The phosphoric acid regeneration device 6 is mainly composed of a receiving tank 70, a processing tank 100, and a storage tank 130. The receiving tank 70 is
The phosphoric acid recovered from the circulation filtration path portion 5 is a place where the phosphoric acid is stored, and the treatment tank 100 is a place where regeneration treatment is performed.
The storage tank 130 is a place for storing the regenerated phosphoric acid.

In the phosphoric acid regenerator 6, as shown in FIG. 1, a first branch pipe 60 is provided between the pump 50 and the filter 51 of the circulation filtration passage section 5. The first branch pipe 60 connects the circulation filtration route portion 5 and the receiving tank 70, and is provided with an automatic valve 61 and a flow meter 62. The flow meter 62 is
It is an integrating type, and measures the amount of phosphoric acid recovered from the circulation filtration route section 5 to the receiving tank 70. Phosphoric acid in the circulation filtration path portion 5 is directly recovered in the receiving tank 70 via the first branch pipe 60 when the automatic valve 61 is in the open state.

In the etching bath 3, in order to carry out the etching under the optimum conditions, it is necessary to discharge the phosphoric acid having a high silicon oxide concentration. By taking such a structure,
The phosphoric acid overflowed when the wafer cassette 2 is loaded is reliably collected in the receiving tank 70. That is, part of the phosphoric acid having a high silicon oxide concentration in the etching bath 3 can be reliably discharged.

Between the pump 50 and the filter 51,
The second branch pipe 63 and the flow rate adjusting means (the pressure gauge 65, the needle valve 67, etc.) can be provided on the downstream side of the location where the first branch pipe 60 is provided. That is, the second
The branch pipe 63 is provided with a pressure gauge 65, a flowmeter 66, a needle valve 67, and an automatic valve 68. The pressure gauge 65 measures the fluid pressure (circulating fluid pressure or filtration pressure) in front of the filter 51, and the flowmeter 66 is an integrating type, and phosphoric acid branched through the branch pipe 63 (target of regeneration treatment). Flow rate of phosphoric acid). The needle valve 67 is a flow rate adjusting valve, and the valve opening of the needle valve 67 is automatically controlled according to the circulating fluid pressure described above. The automatic valve 68 is an opening / closing valve, and when the automatic valve 68 is open, the second branch pipe 63
The phosphoric acid branched from 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 phosphoric acid recovered. The measured data is transmitted to the control circuit 300 described later, and the control circuit 300 controls opening / closing of the automatic valve 101 based on the collected 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 a pure water supply means for adding pure water into the tank, a pure water supply pipe 108 inside the tank, and HF.
An HF tank 109 and a metering pump 110, which are chemical liquid supply means for supplying a necessary amount of (hydrofluoric acid, that is, hydrogen fluoride) 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.

A filter pipe 116 is provided at the outlet 115, and the filter pipe 116 includes an automatic valve 117, a pump 118, a filter 119 (filter section), and a heater 12.
0 is a circulation path for circulating the phosphoric acid in the processing tank 100. That is, the phosphoric acid discharged from the discharge port 115 is returned to the processing tank 100 from the supply port 112 by the pump 118, filtered through the filter 119, and heated by the heater 120. By thus providing the filter 119,
It is possible to remove foreign matters and particles in the regenerated phosphoric acid.

The filter pipe 116 is provided with a branch pipe 121. The branch pipe 121 is provided with an automatic valve 122, and the phosphoric acid that has been regenerated is discharged to the storage tank 130 via the automatic valve 122.

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. The concentration of fluorine in the phosphoric acid in the processing tank 100 is calculated based on the conductivity data measured by the conductivity meter by arithmetic processing in the control circuit (microcomputer etc.) 300 which is the main control means of the apparatus. To be done. The control circuit 300 calculates the amounts of hydrofluoric acid and pure water added according to the amount of phosphoric acid in the treatment tank 100, and the metering pumps 110, 110 so as to satisfy each calculated amount.
107, notifying the end of regeneration when the fluorine concentration falls below a predetermined value, controlling the above-mentioned automatic valves, needle valves, metering pumps, etc. of each part as necessary, and the heater controller of each part. Necessary signals are exchanged between the wafer processing apparatus and the like to control the entire wafer processing apparatus.

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.

In the storage tank 130, a surface heater 131 and a surface heater 132, which are heating means, and a liquid level sensor 133.
, A temperature sensor 134, and a heater controller 135. The surface heater 131 and the surface heater 132 are
The stored regenerated phosphoric acid is heated to a predetermined temperature, and the temperature sensor 1
34 detects the temperature of phosphoric acid in the tank, and the heater controller 135 controls the surface heater 131 and the surface heater 132 based on the detected temperature. In addition, the storage tank 130
Can be equipped with a metering pump 136, which is a pure water supply means for adding pure water into the tank, and a pure water 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. Such adjusted phosphoric acid 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 results of the flowmeters 62 and 66 described above, the control circuit 300 causes the pump 141 and the needle valve 14 to operate.
By transmitting the signal to the storage tank 4, the regenerated phosphoric acid in the storage tank 130 is supplied to the overflow portion 3a. Further, the replenishment pipe 140a is provided with the new liquid supply unit 8. Specifically, in the supply pipe 140a, the needle valve 14
4 and the supply port 33 of the etching tank 3
0 is provided, and the branch pipe 150 is connected to the supply pipe 14
0a and a new phosphoric acid tank 153 are connected. A pump 152 and an automatic valve 151 are provided in the branch pipe 150, and new phosphoric acid solution is supplied through the branch pipe 150 as needed. (Device Operation) Next, an example of the operation or operation of the above wafer processing device will be outlined. First, a wafer 1 having a nitride film
Is stored in the wafer cassette 2, and is placed in the etching tank 3 filled with heated phosphoric acid, the nitride film of the wafer 1 is etched by the hot phosphoric acid. 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 is heated to a desired temperature (for example, the temperature immediately before the boiling point of phosphoric acid) by the line heater 52. A predetermined amount of pure water is added to the heated phosphoric acid through the metering pump 55, and the phosphoric acid is sent from the supply port 35 into the main body of the etching tank 3 and circulated. In this way, since phosphoric acid is circulated in the etching bath 3,
The nitride film on the wafer 1 is appropriately etched.

A part of the phosphoric acid circulated in the circulation filtration path portion 5 flows into the receiving tank 70 via the first branch pipe 60. For example, when loading the wafer cassette 2,
By opening the automatic valve 61, the phosphoric acid that overflows when the wafer cassette 2 is loaded can be collected in the tank 70. In the wafer processing apparatus of the present invention, in order to maintain the phosphoric acid in the etching tank 3 suitable for the process,
It is necessary to discharge at least part of the phosphoric acid having a high silicon oxide concentration. When the above control is performed, the overflowing phosphoric acid when the wafer cassette 2 is loaded can be recovered, and thus the phosphoric acid can be reliably discharged.

At this time, the flow meter 62 measures the amount of phosphoric acid collected in the receiving tank 70 from the circulation filtration passage portion 5, and the detection result is transmitted to the control circuit 300.

As a method of recovering phosphoric acid from the circulation filtration passage portion 5, in addition to the method of performing it through the above-mentioned first branch pipe 60, the filtration pressure of the filter 51 is measured and various valves are operated according to the filtration pressure. There is a method of adjusting and collecting. Specifically, in the treatment process, when the concentration of silicon oxide in phosphoric acid becomes high, the amount of silicon oxide deposited on the filter 51 increases, and the filtration pressure of the filter 51, that is, the circulating fluid pressure in front of the filter 51 in the circulation filtration path portion 5, increases. Get higher In this case, if the pressure value (circulating fluid pressure) measured by the pressure gauge 65 is a predetermined value or more, the automatic valve 68 is closed, and if the pressure value exceeds the predetermined value, the automatic valve 68 is opened. And receive phosphoric acid 70
To collect. At this time, the flow meter 66 measures the amount of phosphoric acid recovered from the circulation filtration path unit 5 into the receiving tank 70, and the detection result is transmitted to the control circuit 300.

When the phosphoric acid in the circulating filtration passage 5 is recovered in the receiving tank 70 by the control as described above, the amount of phosphoric acid in the receiving tank 70 increases accordingly, and the etching tank 3
Reduces the amount of phosphoric acid.

In the etching tank 3, phosphoric acid is replenished based on the liquid amount measured by the flowmeters 62 and 66. First, the control circuit 300 opens the automatic valve 143 of the supply pipe 140a. The regenerated phosphoric acid in the storage tank 130 is supplied to the overflow portion 3a from the supply port 33 of the etching tank 3 via the needle valve 144. Then, the amount of phosphoric acid supplied to the overflow portion 3 a is measured by the liquid level sensor 36, and the detection result is transmitted to the control circuit 300. The control circuit 300 closes the automatic valve 143 when an appropriate amount is supplied. The phosphoric acid supplied to the overflow portion 3 a is discharged from the discharge port 34 and is supplied to the etching tank 3 via the circulation filtration path portion 5.

At this time, the control circuit 300 controls the storage tank 13
Based on the detection result of the liquid level sensor 133 of 0 or the detection result of the temperature sensor 134, it is determined whether the amount of phosphoric acid in the storage tank 130 is sufficient. Then, when the amount of regenerated phosphoric acid in the storage tank 130 is insufficient, the automatic valve 151 of the branch pipe 150 is opened to supply new phosphoric acid in the new liquid supply unit 8. In this way, the liquid level in the etching tank 3 can be kept constant.

In this case, since the regenerated phosphoric acid in the storage tank 130 is regenerated in the treatment 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.

Therefore, in this structure, not only the increase of the circulating fluid pressure (filtration pressure) due to the clogging of the filter 51 is eliminated but also the concentration of silicon oxide in the phosphoric acid in the etching tank 3 is lowered, so that the etching tank 3 Phosphoric acid has a silicon oxide concentration of a desired etching rate ratio, that is, phosphoric acid having a high etching selection ratio between a nitride film and an oxide film and a constant ratio is obtained, and the silicon oxide does not reach a saturated dissolution value.

The receiving tank 70 transmits the data measured by the liquid level sensor 71 to the control circuit 300, and the control circuit 300
The automatic valve 101 is controlled 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. In this way, the processing tank 1
The phosphoric acid in 00 is circulated through the filter pipe 116 and passed through the filter 119, so that impurities and particles in phosphoric acid can be removed.

In the regenerating process, an appropriate amount of hydrofluoric acid in the HF tank 109 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 pure water supply pipe 108. Supplied. For the amounts of hydrofluoric acid and pure water to be supplied, refer to, for example, the relevant portions of JP-A No. 11-293479.
In this regeneration process, the surface heaters 103 and 104 are controlled to raise the temperature of the liquid in the processing tank 100, and the vaporized vapor is guided from the vapor outlet 113 to the cooler 200 to be cooled and returned to the liquid. This liquid is stored in a constant temperature bath 201.
It is poured into the heat insulation container 203 while being adjusted to a constant temperature through the spiral tube inside. It should be noted that new liquid is always flowed into the heat retaining container 203 so that old liquid does not collect. 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, the automatic valve 1 of the filtration pipe 116
17 is in a closed state, the automatic valve 122 of the branch pipe 121 is in an open state, and the branch pipe 121 is discharged to the storage tank 130. The storage tank 130 measures the liquid level by the liquid level sensor 133, and the opening time of the automatic valve 122 is controlled by the measurement result.

The phosphoric acid in the storage tank 130 is supplied to the surface heater 13.
The temperature is maintained at a predetermined temperature (for example, a temperature just before the boiling point) by 1,132, and the pure water supply pipe 137 and the metering pump 1
Pure water is supplied by 36, and the concentration and temperature are adjusted.

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 concentration of phosphoric acid in the tank is adjusted by adding pure water through the metering pump 136 and the pure water supply pipe 137, and the temperature is adjusted to adjust the phosphoric acid used in the process. It can be in the same state as. As a result, the process treatment can be started immediately after being supplied to the etching bath 3.

The phosphoric acid in the storage tank 130 whose concentration and temperature have been adjusted as described above is stored by opening the automatic valve 143 based on the measurement results of the flowmeters 62 and 66 as described above. The phosphoric acid in the tank 130 is supplied via the pump 141, the automatic valve 143, and the needle valve 144. The phosphoric acid in the storage tank 130 is supplied from the replenishment pipe 140a to the needle valve 1 when the automatic valve 143 is closed.
It circulates through 42 and circulation piping 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 1
This is to keep the phosphoric acid temperature in 30 as constant as possible.

The supply pipe 140a is connected to the storage tank 130.
When the phosphoric acid in the inside is insufficient or cannot be supplied to the etching tank 3 due to the fact that the temperature and the concentration cannot be adjusted, the automatic valve 151 of the branch pipe 150 is opened and new phosphoric acid is added. The liquid 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 regenerator 6, the phosphoric acid which is the waste liquid can be suppressed as much as possible, and not only the cost can be reduced but also the adverse effect on the environment can be suppressed.

The present invention is not limited to the above embodiments, and various modifications and developments are possible within the scope of the gist of the present invention. For example, the following modes can be adopted. it can.

In the circulation filtration route section 5, in order to recover the phosphoric acid in the receiving tank 70, two branch pipes are not provided.
One branch pipe can play a role of collecting depending on the circulating pressure and a role of collecting overflowed phosphoric acid.

The regenerated phosphoric acid in the storage tank 130 may be supplied not to the overflow portion 3a but to the circulation filtration path portion 5 as shown in FIG. 1 or to the main body of the etching tank 3. When supplying to the circulation filtration route section 5, the supply pipe 1
A branch supply pipe 160 can be provided at 40a. The branch supply pipe 160 is used for the filter 51 of the circulation filtration path unit 5.
It can be connected to the more upstream side 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. Further, since the particles pass through the filter 51, when the phosphoric acid after regeneration contains particles, there is an advantage that such particles can be removed.

Further, when the etching tank 3 has a large capacity, the processing tanks 100 are provided in pairs, and the recovered phosphoric acid in the receiving tank 70 is introduced into both processing tanks 100 by a switching method for regeneration processing. Good.

The new solution supply unit 8 can be directly installed in the inlet 33 of the etching tank 3 without being installed in the replenishment pipe 140a.

Regarding the replenishment of phosphoric acid to the etching bath 3, a liquid level sensor for measuring the amount of phosphoric acid in the bath is provided in the etching bath 3, and the automatic valve 143 is provided based on the detection result.
Can be controlled to replenish the phosphoric acid.

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 method of discharging phosphoric acid from the circulation filtration passage portion 5, in addition to the above, a discharge pump can be provided in the first branch pipe 60 or the second branch pipe 63.
When the discharge pump 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 there is a limitation in the arrangement of the device. In this case, by operating the pump, the phosphoric acid in the etching tank 3 can flow back into the receiving tank 70 while flowing backward through the circulation filtration path portion 5. For example, in the case of recovering the entire amount of phosphoric acid in the etching tank 3, the discharge pump can be used to recover phosphoric acid in the etching tank 3 in a short time. Further, when the discharge pump is not used, the container into which phosphoric acid is introduced must be installed at the lower side, and the arrangement of the device is limited. However, such a problem can be solved by using a pump for discharge. The pump for discharging is provided in the first branch pipe 60 and the second branch pipe 63, and in addition to the receiving tank 70 and the processing tank 10.
A pipe connecting 0 and the processing tank 100 and the storage tank 1
It can be used for a pipe used when inflowing phosphoric acid, such as a pipe connecting with 30.

As described above, in the wafer processing apparatus of the present invention, when the amount of phosphoric acid in the etching tank 3 is insufficient, regenerated phosphoric acid or new phosphoric acid is automatically supplied. As a result, the liquid level of phosphoric acid in the etching tank 3 can be kept constant, and stable etching processing can be performed.

[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.

[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 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 branch 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 EE22 EE24 EE25                       EE28 EE29 EE33

Claims (10)

[Claims] 1. An etching tank with an overflow portion for etching a semiconductor wafer with hot phosphoric acid, and 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 that returns to the inside of the tank, a phosphoric acid regenerator that heat-treats by adding hydrofluoric acid to phosphoric acid taken out from the circulation filtration route part through a branch pipe, and a phosphoric acid regenerated by the phosphoric acid regeneration device A replenishment pipe for replenishing the etching tank, and a new solution supply unit for supplying a new phosphoric acid solution to the etching tank in accordance with the amount of regenerated phosphoric acid in the phosphoric acid regenerator,
Processing equipment including. 2. The phosphoric acid regenerator according to claim 1, wherein the phosphoric acid taken out from the circulation filtration path is temporarily put in a receiving tank, and the phosphoric acid introduced from the receiving tank is hydrofluoric acid-added and heated. A tank and a storage tank for temporarily storing the phosphoric acid regenerated in the processing tank, wherein the processing tank includes a cooler for cooling and liquefying vapor evaporated from the processing tank, and the cooler. A processing apparatus comprising: a constant temperature bath for adjusting the liquefied liquid 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 means according to claim 1 or 2, wherein the branch pipe is provided in front of a filtration unit that performs filtration in the circulation filtration path unit, and causes phosphoric acid overflowing in the overflow unit to flow into the receiving tank. A processing device. 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.