JP2004179310A - Etching solution, processing method and processing apparatus using this etching solution, and method of manufacturing semiconductor device - Google Patents

Abstract

An etching solution capable of reducing a processing time, a processing method using the etching solution, a processing apparatus, and a method for manufacturing a semiconductor device are provided.
The etching solution of the present invention is an etching solution for selectively etching a nitride film, and the etching solution is a phosphoric acid solution to which hydrofluoric acid is added. The processing method of the present invention includes selectively etching the nitride film using an etching solution comprising a phosphoric acid solution to which hydrofluoric acid has been added, detecting the content of hydrofluoric acid in the etching solution, Means for controlling the concentration of hydrofluoric acid in the etching solution based on the content.
[Selection diagram] Fig. 1

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
In the present invention, a silicon nitride film (hereinafter, abbreviated as "nitride film") such as a semiconductor wafer (for example, a Si wafer, hereinafter, abbreviated as "wafer") is referred to as a phosphoric acid solution (hereinafter, abbreviated as "phosphoric acid"). Liquid), a wafer processing method and a wafer processing apparatus using the etching liquid.
[0002]
BACKGROUND ART AND PROBLEMS TO BE SOLVED BY THE INVENTION
2. Description of the Related Art In wafer processing in the manufacture of semiconductor devices and the like, a process of forming a nitride film pattern on a wafer and selectively forming an oxide film, so-called LOCOS (Local Oxidation Of Silicon), using this nitride film as an oxidation-resistant mask is widely used. Has been. In the LOCOS process, a method of performing etching using a phosphoric acid solution having a large etching selectivity between a nitride film and an oxide film is widely used today to remove an unnecessary nitride film mask.
[0003]
However, the above-described etching process requires a long time, and is one of the processes with a large load in a semiconductor process. By setting the temperature of the phosphoric acid solution and the concentration of the phosphoric acid to optimal conditions, the etching rate of the nitride film can be increased. However, even if such control is performed, there is a limit to the reduction of the processing time.
[0004]
An object of the present invention is to provide an etching solution capable of further reducing the processing time, a processing method and a processing apparatus using the etching solution.
[0005]
[Means for Solving the Problems]
The etching solution of the present invention is an etching solution for selectively etching a nitride film, and the etching solution is a phosphoric acid solution to which hydrofluoric acid is added.
[0006]
According to the etching solution of the present invention, the etching rate of the nitride film can be increased, and the processing time can be greatly reduced.
[0007]
In the etching solution of the present invention, the content of the hydrofluoric acid is determined based on a selectivity between an etching rate of the nitride film and an etching rate of the oxide film (an etching rate of the nitride film / an etching rate of the oxide film), The selectivity is preferably 1 to 10.
[0008]
According to this aspect, the content of hydrofluoric acid is determined by the ratio of the etching rates of the nitride film and the oxide film, and the smaller the selectivity, the higher the content of hydrofluoric acid and the faster the etching rate of the nitride film. be able to. In addition, by setting the selection ratio appropriately according to each film thickness, efficient etching can be performed.
[0009]
The processing method of the present invention includes selectively etching the nitride film using an etching solution comprising a phosphoric acid solution to which hydrofluoric acid has been added,
Means for detecting the content of hydrofluoric acid in the etching solution and controlling the concentration of hydrofluoric acid in the etching solution based on the content.
[0010]
According to the present invention, the content of hydrofluoric acid in the etching solution can be maintained at a desired amount. As a result, stable etching can be performed.
[0011]
The present invention can take the following aspects.
[0012]
(A) In the treatment method of the present invention, the etching may include performing a plurality of treatments with etching solutions having different concentrations of hydrofluoric acid. According to this aspect, the processing is performed a plurality of times according to the thickness of the nitride film, and efficient etching can be performed.
[0013]
(B) In the processing method of the present invention, after the etching is performed using the first etching solution, the etching is performed using a second etching solution having a lower hydrofluoric acid content than the first etching solution. be able to.
[0014]
According to this aspect, the processing time for etching the nitride film can be shortened by using the first etchant, and thereafter, by using the second etchant, the oxide film is not etched more than necessary. The etching process of the nitride film can be completed while controlling. In other words, by using the first and second etching solutions, it is possible to achieve both a reduction in processing time and prevention of overetching of the oxide film.
[0015]
The processing method of the present invention includes selectively etching a nitride film using an etching solution composed of a phosphoric acid solution to which hydrofluoric acid has been added, wherein the etching is performed after the treatment with the first etching solution. The processing is performed using a second etchant having a smaller hydrofluoric acid content than the first etchant.
[0016]
According to the present invention, first, the processing time with which the nitride film is etched can be shortened by processing with the first etchant, and then the oxide film can be etched more than necessary by using the second etchant. The etching process of the nitride film can be completed while controlling so as not to be performed. As a result, it is possible to achieve both a reduction in processing time and prevention of overetching of the oxide film.
[0017]
The present invention can take the following aspects.
[0018]
(A) In the processing method of the present invention, the content of hydrofluoric acid in the first and second etching solutions is determined by selecting ratio of etching rate of nitride film to etching rate of oxide film (etching rate of nitride film / The first etchant may have the selectivity of 1 to 5, and the second etchant may have the selectivity of 1 to 10. .
[0019]
(B) In the processing method of the present invention, in the etching, the content of hydrofluoric acid in the first and second etching solutions is detected, and based on the content, the content of the first and second etching solutions is reduced. Means for respectively controlling the concentration of hydrofluoric acid can be included.
[0020]
According to this aspect, the concentration of hydrofluoric acid in the first and second etching solutions can be maintained at a desired concentration. As a result, stable etching can be performed.
[0021]
The processing apparatus of the present invention includes an etching tank in which an etching liquid is stored, the etching tank detecting a content of hydrofluoric acid in the etching liquid, and a detection unit based on a result detected by the detection unit. A hydrofluoric acid supply unit for supplying a predetermined amount of hydrofluoric acid. The etching solution of the present invention is stored in the etching tank.
[0022]
According to the present invention, to detect the content of hydrofluoric acid in the etching solution, based on the detection result, to have a hydrofluoric acid supply unit for supplying hydrofluoric acid necessary to maintain the desired etching solution, The concentration of hydrofluoric acid in the etching solution can be made constant.
[0023]
The present invention can take the following aspects.
[0024]
In the processing apparatus of the present invention, the etching tank may have a plurality of etching tanks. Further, the etching bath has a first etching bath in which a first etching solution is stored, and a second etching bath in which a content of hydrofluoric acid is smaller than that of the first etching solution and a second etching solution is stored. And two etching baths.
[0025]
According to this aspect, it is possible to have a plurality of etching tanks in which etching solutions having different contents of hydrofluoric acid are stored. Therefore, the etchant to be used can be appropriately switched according to the thickness of the nitride film. Therefore, efficient etching can be performed.
[0026]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described.
[0027]
(First Embodiment)
The etching solution according to the present embodiment is a phosphoric acid solution containing hydrofluoric acid. The amount of hydrofluoric acid contained in the etchant is determined based on the selectivity between the etching rate of the nitride film and the etching rate of the oxide film (the etching rate of the nitride film / the etching rate of the oxide film). The selectivity is preferably from 1 to 10.
[0028]
The effect of the etchant of this embodiment will be described with reference to FIG. FIG. 1 is a graph in which the content of hydrofluoric acid contained in the etching solution is plotted on the horizontal axis and the etching rate of the nitride film is plotted on the vertical axis. In this experiment, a semiconductor wafer having a nitride film having a thickness of 160 nm was prepared, immersed in the etching solution of this embodiment for 20 minutes, and the remaining film thickness was measured to determine the etching rate. Things.
[0029]
As is clear from FIG. 1, it was confirmed that the etching rate of the nitride film increased with the increase of the concentration of hydrofluoric acid. The increase in the etching rate of the nitride film can be considered as follows.
[0030]
In the etching of the nitride film with the phosphoric acid solution, the phosphoric acid acts as a catalyst, and the nitride film and the water are actually etched by causing a reaction represented by the formula (1).
[0031]
SiN ₄ + 6H ₂ O → 3SiO ₂ + 4NH ₃ (1)
And SiO ₂ The reason is considered to be that the reaction of the formula (1) is promoted rightward due to the reaction with hydrofluoric acid in the etching solution, and the etching rate of the nitride film is increased.
[0032]
As described above, the etchant of the present embodiment is effective, for example, for etching a nitride film used as a mask when forming a selective oxide film. In this case, the processing time can be significantly reduced. For example, it takes about 40 minutes to etch a nitride film having a thickness of 200 nm using phosphoric acid that does not contain hydrofluoric acid. However, according to the etchant according to the present embodiment, it is possible to obtain a desired selective oxide film. It was confirmed that the film could be formed in about 28 minutes after the film thickness was secured.
[0033]
(Second embodiment)
1. Wafer processing equipment
The structure of the wafer processing apparatus (processing apparatus) according to the present embodiment will be described with reference to FIG. FIG. 2 is a schematic diagram schematically showing the structure of the wafer processing apparatus according to the present embodiment. In this embodiment, the case where the etching solution according to the first embodiment is used will be described.
[0034]
The wafer processing apparatus 1000 mainly includes an etching unit 100 that can accommodate the semiconductor wafer 1 and a circulation filtration path unit 200.
[0035]
In the etching unit 100, an etching tank 10, an automatic transfer robot (not shown), a belt conveyor and the like (not shown) are arranged together with the etching tank 10, and the wafer 1 is put into and taken out of the tank main body of the etching tank 10 and subjected to etching processing.
[0036]
The etching tank 10 has a tank body defined by an inner peripheral wall 12 and a bottom wall 14, and an overflow portion 10a for receiving phosphoric acid overflowing from the upper end of the inner peripheral wall 12 is formed on the outer periphery. A throw heater, which is a heating element (not shown), is provided inside the inner peripheral wall 12 and the bottom wall 14. A mesh 16 serving as a dispersion plate is provided on the bottom inside of the tank body, and the wafer cassette 2 is held on the mesh 16. The liquid introduction / discharge structure includes a discharge port 18 provided on the bottom wall of the overflow portion 10a and a supply port 20 provided on the bottom wall 14 of the etching tank 10.
[0037]
The control system includes a plurality of liquid level sensors 24 for measuring the level of the phosphoric acid in the overflow section 10a, a temperature sensor 26 for detecting the temperature of the phosphoric acid in the tank body, and a temperature detected by the temperature sensor 26. A heater controller 28 for controlling the heater (not shown) to maintain phosphoric acid at a predetermined temperature is provided.
[0038]
The etching unit 100 has a detection unit 110 for detecting the concentration of hydrofluoric acid in the etching solution. Based on the concentration of hydrofluoric acid detected by the detection unit 110, control for keeping the concentration of the etching solution constant is performed.
[0039]
The detection unit 110 includes a heat exchanger 50 for cooling the steam taken out from the outlet 22 above the overflow unit 10a of the etching tank 10, a cooling water circulating device 52 for circulating the cooling water to the heat exchanger 50, A conductivity meter 56 for calculating the fluorine concentration of phosphoric acid in the container 54 for receiving the liquid that has passed through the heat exchanger 50 is provided. The conductivity meter 56 has a conductivity sensor 58 that measures the conductivity of the liquid in the container 54.
[0040]
The fluorine concentration in the etching solution in the etching tank 10 is calculated by a control circuit (microcomputer or the like) 300 which is the main control means of the apparatus based on the conductivity data measured by the conductivity meter 56. Is done. Further, the control circuit 300 calculates the amount of phosphoric acid, water, hydrofluoric acid, or the like necessary to make the etching solution in the etching tank 10 a desired concentration based on the detected concentration, and sends the calculated amount to the hydrofluoric acid supply unit 120. Send the calculated data. The hydrofluoric acid supply unit 120 includes a supply unit (not shown) of phosphoric acid, hydrofluoric acid, water, and the like, and adjusts the concentration of the phosphoric acid solution so as to be optimal for supplying the etching bath 10. The hydrofluoric acid supply unit 120 and the circulation filtration path unit 200 are connected by a pipe 122. The phosphoric acid solution adjusted by the hydrofluoric acid supply unit 120 is first supplied to the circulation filtration path unit 200 and then supplied to the etching bath 10.
[0041]
The control circuit 300 controls the entire wafer processing apparatus in addition to the control for keeping the content of hydrofluoric acid constant as described above. For example, based on data from the liquid level sensor 24 in the etching tank 10, the amounts of phosphoric acid, hydrofluoric acid, and pure water to be supplied are calculated so that the liquid amount in the etching tank 10 can be maintained at a predetermined amount. Then, various pumps are controlled so as to satisfy each calculated input amount. The automatic valves, needle valves, metering pumps, and the like of the above-described units are controlled as necessary, and necessary signals are exchanged with heater controllers and the like of the units.
[0042]
The circulation filtration path section 200 includes a pump 30 for returning phosphoric acid discharged from the etching tank 10 from the supply port 20 to the tank body of the etching tank 10, a filter 32 for filtering the phosphoric acid, and a filter for filtering the phosphoric acid. The apparatus includes a line heater 34 for setting a predetermined temperature, a temperature sensor 36, a temperature controller 38, and a metering pump 40 for adding a predetermined amount of pure water to phosphoric acid heated to the predetermined temperature. The temperature controller 38 controls the line heater 34 based on data from the temperature sensor 36.
[0043]
That is, in the circulating filtration path section 200, first, the phosphoric acid is filtered by the filter 32 with respect to the etching solution, that is, the phosphoric acid discharged from the overflow section 10a. Next, after the phosphoric acid is heated to a certain temperature by the line heater 34, pure water is added by the metering pump 40 so that the phosphoric acid concentration is adjusted to be constant, and the phosphoric acid is returned into the tank body.
[0044]
In the wafer processing apparatus 1000 of the present embodiment, a detection unit 110 that detects the content of hydrofluoric acid in an etching solution is provided in the etching bath 10. Therefore, by adding hydrofluoric acid or phosphoric acid according to the value to be detected, the content of hydrofluoric acid in the etching solution can be kept constant. As a result, etching with a stable etching rate can be performed.
[0045]
2. Operation method of wafer processing equipment
Next, a wafer processing method using the above-described wafer processing apparatus 1000 will be described. First, the wafer 1 provided with the nitride film is placed in a heated etching tank 10 filled with the phosphoric acid of the present invention in a state of being housed in the wafer cassette 2, and the nitride film of the wafer 1 is subjected to an etching treatment with an etching solution. Is done.
[0046]
In this process, the phosphoric acid solution overflowing from the main body of the etching tank 10 is collected in the overflow section 10a, discharged to the circulation filtration path section 200 from the discharge port 18, and sent to the filter 32 side by the pump 30. The phosphoric acid that has passed through the filter 32 is heated to a desired temperature (for example, a temperature immediately before the boiling point of phosphoric acid) by a line heater 34, and a predetermined amount of pure water is added to the heated phosphoric acid via a metering pump 40. Then, it is sent from the supply port 20 into the main body of the etching tank 10 and circulated. In this way, since the phosphoric acid is circulated to the etching bath 10, the nitride film on the wafer 1 is appropriately etched.
[0047]
In this process, the etching liquid is maintained at about 160 ° C. by a heater (not shown), and the evaporated vapor is taken out from the outlet 22. The removed steam is returned to the liquid in the heat exchanger 50. In the heat exchanger 50, cooling water is circulated by a cooling water circulation device 52. This liquid is poured into the container 54. It is to be noted that new liquid always flows into the container 54 so that old liquid does not accumulate.
[0048]
Subsequently, the conductivity of the liquid in the container 54 is measured by the conductivity meter 56 (conductivity sensor 58), and the measured data is stored in the storage unit of the control circuit 300. The control circuit 300 computes the data to calculate the current fluorine concentration in the etching solution, and adds a chemical solution added to the etching bath so that the content of hydrofluoric acid in the etching bath 10 is maintained at a desired amount. Is calculated.
[0049]
The hydrofluoric acid supply unit 120 prepares necessary amounts of hydrofluoric acid, phosphoric acid, and water to be supplied based on a command from the control circuit 300. Here, a process of diluting a necessary amount of hydrofluoric acid with phosphoric acid and water is performed. This is because the addition amount can be controlled more easily than the method of supplying hydrofluoric acid as it is.
[0050]
Then, the mixed chemical solution adjusted to the optimum concentration is supplied to the circulation filtration path section 200 via the supply pipe 122. The supplied phosphoric acid passes through the filter 32, is heated by the line heater 34, and is supplied from the supply port 20 to the etching bath 10.
[0051]
In the processing method of this embodiment, etching is performed using an etching solution to which hydrofluoric acid is added, so that the etching time can be reduced. Furthermore, control is performed to detect the content of hydrofluoric acid in the etching solution and to keep the content constant. Therefore, etching can be performed while maintaining predetermined conditions, and stable etching can be performed. In addition, the content of hydrofluoric acid in the etchant can be increased or decreased according to the thickness of the nitride film, so that efficient etching can be performed.
[0052]
Since the nitride film serving as a mask for forming the selective oxide film undergoes a heat treatment step, an oxide film is formed on the surface thereof. In this case, before etching the nitride film, the oxide film is etched with hydrofluoric acid, and then the nitride film is etched with a phosphoric acid solution. However, in the processing method of this embodiment, since the processing is performed using a phosphoric acid solution containing hydrofluoric acid, the etching of the oxide film can be performed in the same processing step as the etching of the nitride film. As a result, the processing time can be reduced.
[0053]
When etching the nitride film, as shown in the above equation (1), ₂ Is produced as a reaction product. For this reason, it is difficult to maintain the etching solution under predetermined conditions, and this may cause clogging of various filters. However, in this embodiment, since the hydrofluoric acid is added to the etching solution, the hydrofluoric acid is SiO 2 ₂ Reacts with SiO ₂ Is removed. As a result, particles in the etching solution can be reduced, and a stable etching process can be performed.
[0054]
(Third embodiment)
1. Wafer processing equipment
In the third embodiment, a case will be described in which there are two etching tanks in which etching solutions having different contents of hydrofluoric acid are stored. FIG. 3 is a schematic diagram schematically showing a wafer processing apparatus 2000 according to the third embodiment. Portions having the same functions as those of the wafer processing apparatus 1000 according to the second embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.
[0055]
Wafer processing apparatus 2000 includes etching units 100A and 100B, and transport unit 400 including means for moving a wafer from etching unit 100A to etching unit 100B. Etching units 100A and 100B include etching tanks 10A and 10B, respectively. For example, the first etching liquid can be stored in the etching tank 10A, and the second etching liquid having a lower content of hydrofluoric acid than the first etching liquid can be stored in the etching tank 10B. The specific structures of the etching tanks 10A and 10B can be the same as those of the etching tank 10 described in the second embodiment.
[0056]
And the etching part 100A has the circulation filtration path | pass part 200A, the detection part 110A, and the hydrofluoric acid supply part 120A. The specific configuration, connection relationship, and the like of the circulation filtration path unit 200A, the detection unit 110A, and the hydrofluoric acid supply unit 120A can be the same as those described in the second embodiment. The same applies to the etched part 100B as to the etched part 100A.
[0057]
The control circuit 300 transmits necessary signals to the hydrofluoric acid supply units 120A and 120B based on the detection results of the detection units 110A and 110B. In addition, the control circuit 300 transmits signals to various pumps and valves to control the entire wafer processing apparatus 2000.
[0058]
According to wafer processing apparatus 2000 of the present embodiment, since a plurality of etching tanks filled with phosphoric acid having different contents of hydrofluoric acid are provided, the etching tanks can be switched according to the film to be etched. Thus, efficient etching can be realized.
[0059]
2. Operation method of wafer processing equipment
A wafer processing method using the above-described wafer processing apparatus 2000 will be described.
[0060]
First, the wafer 1 on which the nitride film has been formed is placed in an etching tank 10A filled with heated phosphoric acid while being housed in a wafer cassette 2, and an etching process is performed. In the etching tank 10A, the content of hydrofluoric acid is adjusted so that the selectivity between the etching rate of the nitride film and the etching rate of the oxide film (the etching rate of the nitride film / the etching rate of the oxide film) is 1 to 5. The removed first etching liquid is stored.
[0061]
Subsequently, after the etching in the etching tank 10A is completed, the wafer 1 is taken out in a state of being stored in the wafer cassette 2 by the transfer unit 400, and is placed in the etching tank 10B. The etching bath 10B stores a second etching solution in which the content of hydrofluoric acid is adjusted so that the selectivity (etching rate of the silicon nitride film / etching rate of the silicon oxide film) is 1 to 10. I have.
[0062]
During this treatment process, in the circulation filtration route sections 200A and 200B, similarly to the first embodiment, the phosphoric acid overflowing from each tank is recovered, and filtration with a filter, heating, addition of pure water, and the like are performed. Are supplied again to the etching tanks 10A and 10B and circulated. Similarly to the first embodiment, the detectors 110A and 110B collect the vapor discharged from each tank, cool the vapor and return it to the liquid, and then measure the conductivity of the liquid. This result is transmitted to the control circuit 300, and the control circuit 300 calculates the amount of the chemical solution to be added in order to maintain the current content of hydrofluoric acid in each tank and a predetermined content of hydrofluoric acid. The calculated result is transmitted to the respective hydrofluoric acid supply units 120A and 120B. The hydrofluoric acid supply units 120A and 120B prepare the required amounts of hydrofluoric acid, phosphoric acid, and water to supply the respective tanks based on the information.
[0063]
The transition to the etching bath 10B is preferably performed when the oxide film formed on the surface of the nitride film is removed.
[0064]
Next, a case where the processing method of the present embodiment is applied to a LOCOS forming step will be described with reference to FIG.
[0065]
First, as shown in FIG. 4A, an oxidation resistant mask 6 is formed on a semiconductor substrate (wafer) 1. The oxidation-resistant mask 6 is a film including a nitride film 6b, and preferably has a laminated structure of an oxide film 6a and a nitride film 6b formed thereon. By providing oxide film 6a, stress between semiconductor substrate 1 and nitride film 6b can be reduced.
[0066]
Next, as shown in FIG. 4B, a heat treatment is performed on the semiconductor substrate 1 to form a selective oxide film 5.
[0067]
Thereafter, the semiconductor substrate 1 is carried into an etching tank 10A (see FIG. 3) in which the first etching solution is stored, and the nitride film 6b of the oxidation resistant mask 6 is etched. After a predetermined time, the wafer 1 is taken out of the etching bath 10A, the wafer 1 is carried into the etching bath 10B (see FIG. 3) storing the second etching solution, and the nitride film 6b is subsequently etched. Thus, the LOCOS forming step on the semiconductor substrate 1 is completed.
[0068]
According to the present embodiment, first, the nitride film 6b is etched using the first etchant having a high content of hydrofluoric acid and a high etching rate of the nitride film. Is achieved. Then, by using a second etchant having a lower content of hydrofluoric acid than the first etchant and a lower etch rate of the nitride film, the nitride film is prevented from being over-etched while the selective oxide film is not over-etched. Removal can be completed.
[0069]
Further, in the LOCOS forming step, an oxide film may be formed on the nitride film serving as the oxidation-resistant mask due to the heat treatment for forming the selective oxide film 5. Therefore, usually, a step of removing this oxide film by hydrofluoric acid treatment is necessary as a pretreatment of the nitride film etching step using a phosphoric acid solution. However, in this embodiment, since the phosphoric acid solution containing hydrofluoric acid is used, the oxide film can be removed at the same time as the etching of the nitride film. Thereby, the hydrofluoric acid treatment step can be omitted.
[0070]
Note that the present invention is not limited to the above-described embodiment, and can be modified within the scope of the present invention. For example, the concentration of hydrofluoric acid in the etching solution can be measured by using a known method such as an ion concentration meter instead of the conductivity meter. Further, the present invention can be used not only in the LOCOS forming step but also in all the nitride film etching steps such as the etching step of patterning the nitride film.
[Brief description of the drawings]
FIG. 1 is a diagram showing an experimental result on a first embodiment.
FIG. 2 is a schematic view schematically showing a wafer processing apparatus according to a second embodiment.
FIG. 3 is a schematic view schematically showing a wafer processing apparatus according to a third embodiment.
FIG. 4 is a cross-sectional view schematically showing a manufacturing process of LOCOS formation performed by applying the present invention.
[Explanation of symbols]
1 wafer, 2 wafer cassette, 10, 10A, 10B etching tank, 12 inner wall, 14 bottom wall, 16 mesh, 18 discharge port, 20 supply port, 22 discharge port, 24 liquid level sensor, 26 temperature sensor, 28 heater controller, Reference Signs List 30 pump, 32 filter, 34 line heater, 36 temperature sensor, 38 heater controller, 40 metering pump, 50 heat exchanger, 52 cooling water circulation device, 54 container, 56 conductivity meter, 58 conductivity sensor, 100, 100A, 100B Etching unit, 110, 110A, 110B Detecting unit, 120, 120A, 120B Hydrofluoric acid supply unit, 200, 200A, 200B Circulation filtration path unit, 300 Control circuit, 400 Transport unit, 1000, 2000 Processing device

Claims (13)

An etching solution for selectively etching a nitride film, wherein the etching solution is a phosphoric acid solution to which hydrofluoric acid is added. In claim 1,
The content of the hydrofluoric acid is determined based on a selection ratio between an etching rate of the nitride film and an etching rate of the oxide film (etching rate of the nitride film / etching rate of the oxide film). 10. An etchant. Selectively etching the nitride film using an etching solution comprising a phosphoric acid solution to which hydrofluoric acid has been added,
A processing method, comprising: detecting the content of hydrofluoric acid in the etching solution, and controlling the concentration of hydrofluoric acid in the etching solution based on the content. In claim 3,
A processing method, wherein the etching includes performing a plurality of processes with etching solutions having different hydrofluoric acid contents. In claim 4,
The processing method, wherein the etching is performed using a first etchant, and is then performed using a second etchant having a lower content of hydrofluoric acid than the first etchant. In claim 5,
The content of hydrofluoric acid in the first and second etching solutions is determined based on the selectivity between the etching rate of the nitride film and the etching rate of the oxide film (the etching rate of the nitride film / the etching rate of the oxide film). And
The first etchant has the selectivity of 1 to 5,
The processing method, wherein the second etchant has the selectivity of 1 to 10. Selectively etching the nitride film using an etching solution comprising a phosphoric acid solution to which hydrofluoric acid has been added,
A processing method comprising: performing the etching with a first etchant, and then performing a process with a second etchant having a lower content of hydrofluoric acid than the first etchant. In claim 7,
The content of hydrofluoric acid in the first and second etching solutions is determined based on the selectivity between the etching rate of the nitride film and the etching rate of the oxide film (the etching rate of the nitride film / the etching rate of the oxide film). And
The first etchant has the selectivity of 1 to 5,
The processing method, wherein the second etchant has the selectivity of 1 to 10. In claim 7 or 8,
In the etching, a means for detecting the content of hydrofluoric acid in the first and second etching solutions and controlling the concentrations of hydrofluoric acid in the first and second etching solutions based on the contents is provided. Including, processing method. An etching tank for storing the etching solution according to claim 1 or 2,
A detecting unit that detects the content of hydrofluoric acid in the etching solution in the etching tank; and a hydrofluoric acid supply unit that supplies a predetermined amount of hydrofluoric acid based on a result detected by the detecting unit. , Processing equipment. In claim 10,
The processing apparatus, wherein the etching tank includes a plurality of etching tanks. In claim 11,
The etching bath,
A first etching tank in which a first etching solution is stored;
A second etching tank that stores a second etching solution and has a lower content of hydrofluoric acid than the first etching solution. A method for manufacturing a semiconductor device, comprising using the processing method according to claim 3.

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