JPH09270407A - Method for manufacturing semiconductor device - Google Patents

Abstract

(57) Abstract: A resist residue is completely removed during wet etching of a silicon oxide film using buffered hydrofluoric acid. A silicon oxide film 2 is etched with buffered hydrofluoric acid using a photoresist 3 as a mask, the photoresist 3 is removed by ashing, and then an etching product 2a is removed by washing with dilute hydrofluoric acid water. After that, the resist residue 5 is removed by washing with sulfuric acid and hydrogen peroxide.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a semiconductor device, and more particularly to a method for removing or preventing a resist residue generated during wet etching of a silicon oxide film.

[0002]

2. Description of the Related Art In the manufacture of semiconductor devices, for example, buffered hydrofluoric acid (Buffered Hydrofluoric Acid) is used as a method for finely processing a silicon oxide film used for element isolation and insulating films between wirings.
There is a wet etching method using ydrogen Fluoride (BHF).

For example, in a well forming process or the like, FIG.
As shown in (a), a silicon oxide film 32 covering a large area is formed on the semiconductor substrate 31, and the silicon oxide film 32 is formed.
After applying the photoresist 33 thereon, the photoresist 33 is patterned into a predetermined pattern. Next, FIG.
As shown in (b), BHF is used to form the photoresist 33.
Is used as a mask to wet-etch the silicon oxide film 32. Note that FIG. 3B shows a state in the middle of etching. Next, as shown in FIG. 3C, the photoresist 33 is removed by ashing.

[0004]

However, in the above-mentioned conventional method, as shown in FIG. 3 (b), the etching product 32a is generated during the wet etching of the silicon oxide film 32 by BHF, and the etching product 32a is generated. Thing 3
2a adheres to the patterned photoresist 33. Then, as shown in FIG. 3C, in the subsequent step of removing the photoresist 33 by ashing,
The above-mentioned etching product 32a serves as a mask, and a part of the photoresist 33 is not removed so that the silicon oxide film 3 is not removed.
2 will remain on top. There is a problem in that the photoresist 33 covered with the etching product 32a cannot be removed even if a subsequent organic substance removal treatment such as a sulfuric acid / hydrogen peroxide cleaning is performed.

Further, if a semiconductor wafer is put in a high temperature diffusion furnace while leaving the photoresist residue as described above, organic contamination in the furnace is caused,
For example, there is a problem that the breakdown voltage of a silicon oxide film formed in a furnace is deteriorated.

Therefore, it is an object of the present invention to provide a method of manufacturing a semiconductor device which is capable of surely removing the etching product and the photoresist on the surface layer of the photoresist and which has a high throughput.

[0007]

According to a method of manufacturing a semiconductor device of the present invention, a resist pattern is formed on a silicon oxide film formed on a semiconductor substrate, and the silicon oxide film is formed using the resist pattern as a mask. A first step of etching with buffered hydrofluoric acid; a second step of cleaning the semiconductor substrate with dilute hydrofluoric acid water after the first step; and a resist of the second step after the second step. A third step of performing an ashing process for removing the pattern.

According to another aspect of the present invention, there is provided a method of manufacturing a semiconductor device, wherein a resist pattern is formed on a silicon oxide film formed on a semiconductor substrate, and the resist pattern is used as a mask to buffer the silicon oxide film. A first step of etching with hydrofluoric acid, a second step of performing an ashing process for removing the resist pattern after the first step, and a dilute hydrofluoric acid solution after the second step. And a third step of cleaning the semiconductor substrate using the same.

In one aspect of the present invention, after the third step,
The method further includes a fourth step of cleaning the semiconductor substrate with sulfuric acid.

[0010]

FIG. 1 is a process sectional view of a method for manufacturing a semiconductor device according to a first embodiment of the present invention.

First, as shown in FIG. 1A, a silicon thermal oxide film 2 having a film thickness of about 1000 Å is grown on a silicon semiconductor substrate 1, and a resist pattern 3 is formed on the silicon thermal oxide film 2 by photolithography. To form.

Next, as shown in FIG. 1B, wet etching is performed on the silicon thermal oxide film 2 using a BHF chemical solution (not shown). The wet etching conditions at this time are, for example, a BHF chemical solution temperature of about 23 ° C. and a wet etching time of about 4 minutes. As a result of this treatment, a desired etching shape of the silicon thermal oxide film 2 is obtained, but during the process, a large amount of etching products (not shown) are generated in the BHF chemical solution, and a part of the etching products is generated. Etching products 2a of the above adhere to the resist pattern 3.

Next, as shown in FIG. 1C, a substrate temperature of, for example, 200 is measured by a resist removing device (not shown).
℃, microwave frequency 2.45GHz, output 800W, O
_{2 The} resist pattern 3 is removed under the conditions of a gas flow rate of 200 ccm, a processing pressure of 1.0 Torr, and a processing time of 130 seconds. Then, as shown in the figure, the resist residue 5 covered with the etching product 2a remains on the silicon thermal oxide film 2.

Then, next, as shown in FIG.
The silicon semiconductor substrate 1 is washed with diluted hydrofluoric acid water having a volume ratio of approximately BHF: pure water = 1: 100. The dilute hydrofluoric acid water cleaning conditions at this time are, for example, a dilute hydrofluoric acid chemical temperature of 23 ° C. and a treatment time of about 3 minutes. By performing this process, the etching product 2a is removed and the resist residue 5 is exposed. By the way, the etching rate of the dilute hydrofluoric acid water used for this treatment with respect to the silicon thermal oxide film 2 is 10 Å / min or less.

Next, as shown in FIG. 1 (e), the silicon semiconductor substrate 1 is washed with sulfuric acid / hydrogen peroxide mixture, for example, sulfuric acid / hydrogen peroxide mixture having a volume ratio of about sulfuric acid: hydrogen peroxide water = 5.5: 1. 1
By performing the treatment at 30 ° C. for 15 minutes, a good state without the resist residue 5 can be obtained.

2A to 2D are sectional views showing steps of a method of manufacturing a semiconductor device according to the second embodiment of the present invention.

In the second embodiment, the diluted hydrofluoric acid cleaning treatment performed in the first embodiment is performed immediately after the wet etching step, not after the resist pattern removing step.

First, as shown in FIG. 2A, a silicon thermal oxide film 22 having a film thickness of about 1000 Å is grown on a silicon semiconductor substrate 21, and a resist pattern 23 is formed on the silicon thermal oxide film 22 by photolithography. To form.

Next, as shown in FIG. 2B, wet etching is performed on the silicon thermal oxide film 22 using a BHF chemical solution (not shown). The wet etching conditions at this time are, for example, a BHF chemical solution temperature of about 23 ° C. and a wet etching time of about 4 minutes. As a result of this treatment, a desired etching shape of the silicon thermal oxide film 22 is obtained, but during the process, a large amount of etching products (not shown) are generated in the BHF chemical solution, and a part of the etching products is generated. Etching product 22a of the above adheres to the resist pattern 23.

Then, next, as shown in FIG.
The silicon semiconductor substrate 21 is washed with diluted hydrofluoric acid water having a volume ratio of approximately BHF: pure water = 1: 100. The dilute hydrofluoric acid water cleaning conditions at this time are, for example, a dilute hydrofluoric acid chemical temperature of 23 ° C. and a treatment time of about 3 minutes. By performing this treatment, the etching product 22a is substantially completely removed. By the way, the silicon thermal oxide film 22 of the diluted hydrofluoric acid water used for this treatment is used.
Since the etching rate is less than 10 Å / min, the etching shape of the silicon thermal oxide film 22 is hardly affected.

After this, as shown in FIG. 2D, a substrate temperature of 200, for example, is set by a resist removing device (not shown).
℃, microwave frequency 2.45GHz, output 800W, O
_{2 The} resist pattern 23 is removed under the conditions of a gas flow rate of 200 ccm, a processing pressure of 1.0 Torr, and a processing time of 130 seconds. This makes it possible to obtain a good state in which there are no resist residues.

[0022]

According to the present invention, for example, by adding a step of wet-etching a silicon oxide film covering a large area with BHF and then cleaning the silicon substrate with diluted hydrofluoric acid water, Moreover, etching products can be removed, and a high-throughput semiconductor device manufacturing method can be realized.

[Brief description of drawings]

FIG. 1 is a process sectional view showing a method for manufacturing a semiconductor device according to a first embodiment of the present invention.

FIG. 2 is a process sectional view showing the method of manufacturing the semiconductor device according to the second embodiment of the present invention.

FIG. 3 is a process sectional view showing a conventional method for manufacturing a semiconductor device.

[Explanation of symbols]

 1, 21 Silicon semiconductor substrate 2, 22 Silicon thermal oxide film 2a, 22a Etching product 3, 23 Resist pattern 5 Resist residue

Claims (3)

[Claims] 1. A first step of forming a resist pattern on a silicon oxide film formed on a semiconductor substrate, and etching the silicon oxide film with buffered hydrofluoric acid using the resist pattern as a mask. A second step of cleaning the semiconductor substrate with diluted hydrofluoric acid water after the first step, and a third step of performing an ashing process for removing the resist pattern after the second step A method of manufacturing a semiconductor device, comprising: 2. A first step of forming a resist pattern on a silicon oxide film formed on a semiconductor substrate, and etching the silicon oxide film with buffered hydrofluoric acid using the resist pattern as a mask. A second step of performing an ashing process for removing the resist pattern after the first step, and a third step of cleaning the semiconductor substrate with dilute hydrofluoric acid water after the second step A method of manufacturing a semiconductor device, comprising: 3. The method of manufacturing a semiconductor device according to claim 2, further comprising a fourth step of cleaning the semiconductor substrate with sulfuric acid after the third step.