TW201802917A - Substrate processing apparatus and substrate processing method - Google Patents

Abstract

By efficiently generating nitrous acid, the present invention can generate an etching solution having a nitrous acid concentration suitable for etching, thereby improving the efficiency of etching. The substrate processing apparatus of the present invention processes semiconductor wafers using an etching solution containing hydrofluoric acid and nitric acid, which includes: a storage tank to store an etching solution; a concentration sensor to measure a nitrous acid concentration in the etching solution; an alcohol supply unit Supplying isopropyl alcohol to the etching solution to maintain the nitrous acid concentration above a predetermined value; and a substrate processing unit supplying the etching solution in the storage tank to the semiconductor wafer.

Description

Substrate processing device and substrate processing method

TECHNICAL FIELD The present invention relates to a substrate processing apparatus and a substrate processing method in which a processing liquid is supplied to a substrate such as a semiconductor wafer to process the substrate.

BACKGROUND ART A substrate processing apparatus used in a wet etching process of an electronic component such as a semiconductor device or a liquid crystal display device is known (for example, refer to Patent Document 1). As a method for removing a strain layer on a substrate surface or a heavy metal existing on the substrate surface in a manufacturing process of a substrate such as a semiconductor wafer, the substrate processing device is a method of etching a substrate surface with a chemical solution.

As an etching method, for example, a method of supplying an etching solution obtained by mixing hydrofluoric acid (HF), nitric acid (HNO ₃ ), and pure water at a predetermined mixing ratio to a semiconductor wafer has been used. It is known that nitrite (HNO ₂ ) contributes to the etching in the etchant. Therefore, a silicon substrate (semiconductor wafer, etc.) is dissolved in a solution containing hydrofluoric acid and nitric acid to generate nitrous acid, and an etching solution is further generated. Advance technical literature

Patent Literature [Patent Literature 1] Japanese Patent Application Laid-Open No. 11-26425

SUMMARY OF THE INVENTION Problems to be Solved by the Invention In the substrate processing apparatus described above, if the nitrous acid concentration in the etchant is low, the etching processing time of the semiconductor wafer becomes longer. Therefore, although it is necessary to dissolve a sufficient amount of the silicon substrate, dissolution of the silicon substrate takes time, and there is a problem that productivity is reduced.

Here, an object of the present invention is to provide a substrate processing apparatus and a substrate processing method, which can efficiently generate an etching solution having a nitrous acid concentration suitable for etching, and can improve the efficiency of etching. Means to solve the problem

In order to solve the aforementioned problems and achieve an object, a substrate processing apparatus and a substrate processing method of the present invention are configured as follows.

A substrate processing apparatus for processing a substrate using a processing liquid containing hydrofluoric acid and nitric acid. The substrate processing apparatus includes a storage tank that stores the processing liquid, an alcohol supply unit that supplies alcohol to the processing liquid, and a supply unit that The processing liquid to which the alcohol has been supplied is supplied to the substrate.

A substrate processing method for processing a substrate using a processing solution containing hydrofluoric acid and nitric acid. The substrate processing method is to store the aforementioned processing solution in a storage tank, and supply alcohol to the aforementioned processing solution, and supply the aforementioned alcohol. The processing solution is supplied to the aforementioned substrate. Invention effect

According to the present invention, an etching solution having a nitrous acid concentration suitable for etching can be efficiently generated, and the etching efficiency can be improved.

Best Mode for Carrying Out the Invention FIG. 1 is an explanatory diagram schematically showing a substrate processing apparatus 10 according to an embodiment of the present invention, FIG. 2 is an explanatory diagram showing a nitrite generation amount of the substrate processing apparatus 10, and FIG. 3 is a diagram showing An explanatory diagram of an operation flow of the substrate processing apparatus 10. Moreover, W in FIG. 1 shows a semiconductor wafer (substrate).

The substrate processing apparatus 10 includes a substrate processing unit 100, an etching solution supply unit 200 that supplies the etching solution L to the substrate processing unit 100, and a control unit 300 that controls the substrate processing unit 100 and the etching solution supply unit 200.

The substrate processing unit 100 has a structure in which a wafer chuck 102 that supports a semiconductor wafer W in a cup 101 is rotated by a motor 103. Then, as described later, the etching treatment liquid supplied from the etching liquid supply unit 200 is supplied to the semiconductor wafer W from a nozzle (supply unit) 104 disposed above the semiconductor wafer W. An etching process is performed on the surface of the semiconductor wafer W which is rotated in accordance with the rotation of the wafer chuck 102 with the etching solution.

The etching supply unit 200 includes a storage tank 210 containing an etching solution, a recovery tank 220 containing a used etching solution, and a new liquid supply tank 230 containing a mixture of hydrofluoric acid, nitric acid, and acetic acid (CH ₃ COOH) and the new chemical pure water; and the alcohol supply tank 240, receiving as an example of the alcohol of isopropanol (isopropyl alcohol, IPA). An etching solution supply line 250 and a recovery line 260 are respectively provided between the storage tank 210 and the substrate processing unit 100. A recovery tank 220 is interposed in the middle of the recovery line 260. A fresh liquid supply line 270 is provided between the fresh liquid supply tank 230 and the storage tank 210. An alcohol supply line 280 is provided between the alcohol supply tank 240 and the storage tank 210.

The storage tank 210 includes a closed tank body 211 and an open valve 212 provided on an upper portion of the tank body 211.

The recovery tank 220 includes a tank body 221 having a closed structure. The fresh liquid supply tank 230 includes a tank body 231 having a closed structure. The alcohol supply tank 240 includes a tank body 241 having a closed structure.

The new liquid supply tank 230 is connected to a hydrofluoric acid supply pipe 232, a nitric acid supply pipe 233, an acetic acid supply pipe 234, and a pure water supply pipe 235. These are provided with on-off valves 232a, 233a, 234a, and 235a, respectively. A predetermined amount is supplied from each of the supply pipes 232 to 235 to enable mixing at a predetermined ratio as described above.

The etching solution supply line 250 includes a main line 251, the inlet end of which is provided at the bottom of the tank body 211, and the outlet end of which is connected to the nozzle 104 of the substrate processing unit 100; 254 is provided between the pump 252 and the nozzle 104; and a return line 255 is returned from the branch portion 254 to the tank body 211. A concentration sensor 256 and an on-off valve 257 for measuring the nitrous acid concentration are provided in the middle of the return line 255. The density sensor 256 may be provided in the middle of the main line 251.

The recycling line 260 has a main line 261. An inlet end thereof is provided at the bottom of the substrate processing unit 100, and an outlet end thereof is provided in the tank body 211. A groove body 221 and a pump 262 are provided on the main line 261.

The fresh liquid supply line 270 includes a main line 271 having an inlet end provided at the bottom of the tank body 231 and an outlet end provided at the top of the tank body 211; an on-off valve 272 provided on the way of the main line 271; and a pump 273.

The alcohol supply line 280 includes: a main line 281 whose inlet end is provided at the bottom of the tank body 241 and whose outlet end is connected to the tank body 211; a pump 282 is provided on the way of the main line 281; and an on-off valve 284 and a check valve 285 are provided. Between the pump 282 and the tank body 211.

The outlet end of the main line 281 is connected to the tank body 211 at a position below the liquid level of the etching solution L supplied from the tank body 211. That is, as shown in FIG. 1, the configuration is such that isopropyl alcohol is directly supplied to the etching solution L in a state where a certain amount of the etching solution L is accumulated in the tank body 211. In addition, if the liquid level of the etching solution L is considered to be changed, or the specific gravity of isopropyl alcohol is lighter than that of the etching solution L, in order to make the isopropyl alcohol only react near the liquid level of the etching solution L, The exit end of the main line 281 is preferably closer to the bottom wall even if the side wall below the groove body 211 is provided, or is preferably disposed on the bottom wall.

In the present embodiment, the alcohol supply tank 240, the alcohol supply line 280, the main line 281, the pump 282, the on-off valve 284, and the check valve 285 constitute an alcohol supply unit 310.

The on-off valves and pumps are controlled by the control unit 300. The preset nitrous acid concentration (a predetermined value of the nitrous acid concentration) is set by the control unit 300, for example. The control unit 300 controls the substrate processing apparatus 10 as described below.

In this embodiment, an example in which a semiconductor wafer is used as a substrate and an oxide film formed on the surface of the semiconductor wafer is removed by etching will be described.

First, preparations before the process starts will be described. All valves were closed before the process began. Next, the on-off valves 232a, 233a, 234a, and 235a of the hydrofluoric acid supply pipe 232, nitric acid supply pipe 233, acetic acid supply pipe 234, and pure water supply pipe 235 connected to the tank body 231 are opened and closed, Each of the supply pipes 232 to 235 supplies a predetermined amount so that hydrofluoric acid, nitric acid, acetic acid, and pure water can be mixed at a predetermined ratio that has been set in advance, thereby generating a new etching solution L. Next, the open valve 212 and the on-off valve 272 are opened, the pump 273 is operated, and a new etching solution L is supplied into the tank body 211 of the storage tank 210. When a predetermined amount of new etching solution L is accumulated in the tank body 211, the on-off valve 272 is closed, and the supply is stopped. Next, the open valve 212 is closed, the on-off valve 257 is opened, the pump 252 is driven, and the etching liquid L is circulated. Here, the nitrite concentration in the etching solution L is detected by the etching solution L passing through the concentration sensor 256. Although nitric acid itself decomposes to generate nitrous acid, the nitrous acid concentration in the etching solution L is initially low.

Next, the open valve 212 and the on-off valve 284 of the main line 281 of the alcohol supply line 280 are opened, and the pump 282 is driven to supply isopropyl alcohol to the tank body 211. Here, in the tank body 211, nitric acid in the etching solution L is decomposed to generate nitrous acid and nitric acid gas. As a result, the nitrous acid concentration in the etching solution L increases until the nitrous acid concentration detected by the concentration sensor 256 reaches a predetermined value, and the alcohol supply unit 310 continues to supply isopropyl alcohol to the tank body 211. At a time point when the nitrous acid concentration has reached a predetermined value, the open valve 212 and the on-off valve 284 are closed. Then, the pump 282 is stopped to stop the supply of isopropanol. In addition to determining the supply amount of isopropanol by the concentration sensor 256, the necessary supply amount of isopropanol can also be calculated based on conditions such as a predetermined processing time and a predetermined number of processed wafers of a semiconductor wafer.

Fig. 2 is an explanatory diagram comparing the concentration of nitrous acid in a case where a mixture of hydrofluoric acid, nitric acid, acetic acid, and pure water was 100 cc (a nitric acid concentration of 23.8%), and the concentration of nitrous acid was compared with that when 5 µL of isopropyl alcohol was added. It was 224 ppm when left to stand, compared with 1377 ppm when isopropyl alcohol was added, and a 6-fold concentration was achieved.

Returning to FIG. 1, when the amount of the etching solution L in the tank body 211 and the nitrous acid concentration thereof have reached a predetermined value, the pump 252 is stopped to stop the circulation of the etching solution L.

Next, an etching process will be described with reference to FIG. 3. When the etching process is started (ST1), the open valve 212 and the on-off valve 253 are opened, the on-off valve 257 is closed, and the pump 252 is driven. Thereby, the etching liquid L in the tank body 211 is supplied to the nozzle 104 of the substrate processing unit 100 through the main line 251. Then, the etching liquid L is supplied from the nozzle 104 to the surface of the semiconductor wafer W rotated by the driving of the motor 103. The etching liquid L is recovered through the cup 101 and stored in the tank body 221 of the recovery tank 220. The pump 262 is driven to return the stored etching solution L to the tank body 211 in a timely manner. When the etching process of the predetermined number of semiconductor wafers W is completed, the etching process is ended (ST2).

Next, the open valve 212 and the on-off valve 253 are closed, the on-off valve 257 is opened, the pump 252 is driven, and the etching liquid L is circulated. At this time, the concentration of nitrous acid in the etching solution L is detected by the concentration sensor 256. Determine whether the nitrous acid concentration is greater than a predetermined value (ST3). When the nitrous acid concentration is less than a predetermined value, open the on-off valve 284 of the alcohol supply line 280 and drive the pump 282 to supply isopropyl alcohol to the tank body 211 (ST4), and further This produces nitrous acid. As a result, the nitrous acid concentration in the etching solution L increases. Until the nitrous acid concentration detected by the concentration sensor 256 reaches a predetermined value or more, the alcohol supply unit 310 continues to supply isopropyl alcohol to the tank body 211. When the control unit 300 detects from the output value of the concentration sensor 256 that the nitrous acid concentration has reached a predetermined value, the open valve 212, the on-off valve 257, and the on-off valve 284 are closed. Then, the next etching process is started (ST5).

In the etching process of supplying the etching liquid L from the nozzle 104 to the surface of the semiconductor wafer W, the on-off valve 257 may be opened, and the etching liquid L supplied by the pump 252 may be branched to the substrate processing unit by the branching portion 254. 100 与 槽 体 211. At this time, the etching solution supplied from the branching portion 254 to the tank body 211 through the return line 255 detects the nitrous acid concentration in the etching solution L with the concentration sensor 256. That is, while the etching solution L is supplied from the nozzle 104 to the semiconductor wafer W to perform an etching process, the nitrous acid concentration of the etching solution L supplied from the nozzle 104 is detected. At this time, when the detected nitrous acid concentration is equal to or less than a predetermined value, the on-off valve 253 may be closed at this point in time, but it is desirable to close the on-off valve 253 at a point in time when the processing of the semiconductor wafer W in the etching process has ended. , The supply of the etching liquid L to the nozzle 104 is stopped. This is because defective products can be prevented from being caused by stopping the etching process in the middle. Thereafter, as described above, isopropyl alcohol is supplied to the tank body 211 to adjust the nitrous acid concentration in the etching solution L.

Accordingly, according to the substrate processing apparatus 10 of this embodiment, if the nitrous acid concentration of the etching solution L is lower than a predetermined value, nitrous acid can be generated by adding isopropyl alcohol, thereby improving the efficiency of the etching process. Therefore, the production efficiency of the semiconductor wafer W is improved.

FIG. 4 is an explanatory diagram of a main part of a substrate processing apparatus 10A showing a modified example of the substrate processing apparatus 10. In FIG. 4, the same function parts as those in FIG. 1 are assigned the same symbols, and detailed descriptions thereof are omitted.

In the substrate processing apparatus 10A, a nozzle 290 such as a fluid nozzle or the like that sprays isopropyl alcohol in a mist form is provided at an outlet end of the main line 281 constituting the alcohol supply section 310 in the tank body 211. The position of the nozzle 290 is lower than the liquid level of the etching liquid L. Because the isopropyl alcohol is supplied from the nozzle 290, the etching liquid L does not flow back to the main line 281 side. Moreover, the contact area with the etching liquid L is increased by spraying in a mist state, which is larger than the isopropyl liquid supply. Alcohol, it is easier to promote the reaction. The order and effect of the etching process are the same as those of the substrate processing apparatus 10 described above.

FIG. 5 is an explanatory diagram showing a main part of a substrate processing apparatus 10B according to another modification of the substrate processing apparatus 10. In FIG. 5, the same functional parts as those in FIG. 1 are assigned the same symbols, and detailed descriptions thereof are omitted.

The substrate processing apparatus 10B has a configuration in which an outlet end of a main line 281 constituting the alcohol supply unit 310 is connected to a main line 251 of the etchant supply line 250.

In the substrate processing apparatus 10B configured as described above, the etching process of the substrate W is performed as follows. Before the processing is started, a predetermined amount of a new etching solution L is accumulated in the tank body 211 of the storage tank 210 similarly to the substrate processing apparatus 10. Next, the open valve 212 is closed, the on-off valve 257 is opened, and the pump 252 is driven to circulate the etching liquid L. By passing the etching solution L through the concentration sensor 256, the nitrous acid concentration in the etching solution L can be detected.

In addition, the open valve 212 and the on-off valve 284 of the main line 281 are opened, and the pump 282 is driven to supply isopropyl alcohol to the main line 251.

On the other hand, in the tank body 211, nitric acid in the etching solution L is decomposed to generate nitrous acid and nitric acid gas. As a result, the nitrous acid concentration in the etching solution L increases until the nitrous acid concentration detected by the concentration sensor 256 reaches a predetermined value, and the alcohol supply unit 310 continues to supply isopropyl alcohol to the main line 251. At a time point when the nitrous acid concentration has reached a predetermined value, the open valve 212 and the on-off valve 284 are closed. Then, the pump 282 is stopped to stop the supply of isopropanol.

With this configuration, since isopropanol is added to the circulation path of the etching solution L, the mixing of the etching solution L and isopropanol can be promoted. The order and effect of the etching process are the same as those of the substrate processing apparatus 10 described above.

In addition, although the exit end of the main line 281 is connected to the main line 251 of the etching solution supply line 250, it may be connected between the branch portion 254 and the nozzle 104.

In the above examples, although isopropyl alcohol is exemplified as the alcohol, the same effect can be obtained by using ethanol. Gas alcohols and solid alcohols can also be used. In addition to the time when the etching solution L is circulated, the nitrous acid concentration can also be measured during the etching process.

In addition, as a method of supplying the etching liquid L to the semiconductor wafer W, although a substrate processing unit that rotates a substrate to perform processing is used as an example, the etching liquid L may be stored in a processing tank and a plurality of semiconductor crystals may be used. A batch-type in which the circle W is immersed for processing.

When a batch type is adopted, a batch type processing tank may be used instead of the substrate processing unit 100. The storage tank 210 of the etchant supply unit 200 may be replaced with a batch processing tank. In this case, it may be configured such that the alcohol supply line is directly connected to the batch-type processing tank to add isopropyl alcohol.

The substrate is not limited to a semiconductor wafer, and may be a glass substrate such as a liquid crystal substrate or a photomask substrate. The process is not limited to the etching process.

Although several embodiments of the present invention have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. These new embodiments can be implemented in various other forms, and various omissions, substitutions, and changes can be made without departing from the gist of the invention. These embodiments or their modifications are included in the scope or gist of the invention, and are included in the invention described in the scope of patent application and its equivalent scope.

10, 10A, 10B‧‧‧ substrate processing equipment
100‧‧‧ substrate processing unit
101‧‧‧ cup body
102‧‧‧wafer chuck
103‧‧‧ Motor
104‧‧‧Nozzle
200‧‧‧ Etching liquid supply unit
210‧‧‧Storage tank
211, 221, 231, 241‧‧‧ tank body
212‧‧‧Open valve
220‧‧‧ Recovery tank
230‧‧‧ new liquid supply tank
232, 233, 234, 235‧‧‧ supply pipe
232a, 233a, 234a, 235a, 253, 257, 272, 284‧‧‧ on / off valve
240‧‧‧ alcohol supply tank
250‧‧‧ Etching liquid supply line
251, 261, 271, 281‧‧‧ main line
252, 262, 273, 282‧‧‧ pump
254‧‧‧Division
255‧‧‧Return line
256‧‧‧Concentration sensor
260‧‧‧Recycling line
270‧‧‧new liquid supply line
280‧‧‧ alcohol supply line
285‧‧‧Check valve
290‧‧‧Nozzle
300‧‧‧ Control Department
310‧‧‧ Alcohol Supply Department
ST1, ST2, ST3, ST4, ST5 ‧‧‧ steps
L‧‧‧etching solution
W‧‧‧Semiconductor wafer

FIG. 1 is an explanatory diagram schematically showing a substrate processing apparatus according to an embodiment of the present invention. FIG. 2 is an explanatory diagram showing the amount of nitrous acid produced in the substrate processing apparatus. FIG. 3 is an explanatory diagram showing an operation flow of the substrate processing apparatus. FIG. 4 is an explanatory diagram showing a modification of the substrate processing apparatus. FIG. 5 is an explanatory diagram showing another modified example of the substrate processing apparatus.

10‧‧‧ substrate processing equipment

100‧‧‧ substrate processing unit

101‧‧‧ cup body

102‧‧‧wafer chuck

103‧‧‧ Motor

104‧‧‧Nozzle

200‧‧‧ Etching liquid supply unit

210‧‧‧Storage tank

211, 221, 231, 241‧‧‧ tank body

212‧‧‧Open valve

220‧‧‧ Recovery tank

230‧‧‧ new liquid supply tank

232, 233, 234, 235‧‧‧ supply tube

232a, 233a, 234a, 235a, 253, 257, 272, 284‧‧‧ on / off valve

240‧‧‧ alcohol supply tank

250‧‧‧ Etching liquid supply line

251, 261, 271, 281‧‧‧ main line

252, 262, 273, 282‧‧‧ pump

254‧‧‧Division

255‧‧‧Return line

256‧‧‧Concentration sensor

260‧‧‧Recycling line

270‧‧‧new liquid supply line

280‧‧‧ alcohol supply line

285‧‧‧Check valve

300‧‧‧ Control Department

310‧‧‧ Alcohol Supply Department

L‧‧‧etching solution

W‧‧‧Semiconductor wafer

Claims (10)

A substrate processing apparatus for processing a substrate using a processing liquid containing hydrofluoric acid and nitric acid, comprising: a storage tank that stores the processing liquid; an alcohol supply unit that supplies alcohol to the processing liquid; and a supply unit that supplies the processed liquid The processing liquid supplied with the alcohol is supplied to the substrate. The substrate processing apparatus according to claim 1, wherein the alcohol supply unit supplies the alcohol to a position lower than a liquid level of the processing liquid stored in the storage tank. For example, the substrate processing apparatus of claim 1 includes: a main line connecting the supply unit and the storage tank; a branch unit provided on the way of the main line; and a return line connected to the storage tank from the branch unit. For example, the substrate processing apparatus of claim 3 further includes a concentration sensor that detects a nitrous acid concentration in the processing solution supplied by the supply unit, and the nitrous acid concentration detected by the concentration sensor is a predetermined value. In the following, the alcohol supply unit supplies alcohol to the processing liquid. For example, the substrate processing apparatus of claim 4, further comprising a control unit, which stops the supply of the processing solution by the supply unit when the nitrous acid concentration in the processing solution detected by the concentration detector is lower than a predetermined value; When the control unit detects that the nitrous acid concentration in the processing liquid is lower than a predetermined value by the concentration sensor during the processing of the substrate, after the processing of the substrate is completed, the supply unit stops supplying the processing. liquid. The substrate processing apparatus according to claim 3, wherein the alcohol supply section supplies the alcohol to the storage tank and the branching section in the main line. A substrate processing method for processing a substrate using a processing liquid containing hydrofluoric acid and nitric acid, characterized in that the processing liquid is stored in a storage tank, alcohol is supplied to the processing liquid, and a processing liquid that has been supplied with the alcohol It is supplied to the aforementioned substrate. The substrate processing method according to claim 7, wherein when the alcohol is supplied into the storage tank, the alcohol is supplied at a position lower than a liquid level of the processing liquid stored in the storage tank. The substrate processing method according to claim 7, wherein a part of the nitrous acid concentration of the processing liquid supplied from the storage tank to the substrate is returned to the storage tank while the substrate is detected. If the substrate processing method of claim 9 is used, in the processing of the substrate, if the nitrous acid concentration in the processing liquid is lower than a predetermined value, the supply of the processing liquid is stopped after the processing of the substrate is completed.