JPH07297199A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To obtain an aluminum wiring layer in a correct size by a method wherein a resist pattern containing a light absorbent is used as a mask and a nitride film under it and an aluminum layer are etched and removed. CONSTITUTION:A nitride film 12 is formed on an aluminum layer 11, a resist film 13 containing a light absorbent is formed on the nitride film 12, a desired region in the resist film 13 containing the light absorbent is exposed and then developed, and a resist pattern 13A is formed. By making use of the resist pattern 13A as a mask, the nitride film 12 and the aluminum layer 11 are etched and removed, and a wiring layer 11A is formed. As a result, when the film thickness of the nitride film 12 as a substratum film for the resist film 13 containing the light absorbent is set to a proper film thickness, the reflectance on the surface of the substratum film is reduced considerably. Thereby, the bad influence of a halation, in the exposure process of the resist film 13 containing the light absorbent, which is caused mainly by reflected light from the substratum film can be suppressed to a considerable extent.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a semiconductor device, and more particularly to an improvement of a method of forming a wiring used in a semiconductor device which has been highly miniaturized.

[0002]

2. Description of the Related Art A conventional method of manufacturing a semiconductor device will be described below with reference to FIGS. First, as shown in FIG. 7, LOCOS is formed on the Si substrate (1).
After forming a selective oxide film (2) for element isolation by (Local Oxidation of Silicon) method, polysilicon is selectively formed on the selective oxide film (2) to form a polysilicon gate (3).
And BPSG [Boro-P
After forming the hoso Silicate Glass] film (4), an aluminum layer (5) is formed on the entire surface.

Next, a resist is applied on the entire surface to form a resist film (6), and the photomask (7) is used as a mask to expose the resist film (6) using a g-line having a wavelength λ = 435 nm. . Next, the resist film (6) is developed to remove the exposed area, and a resist pattern (6A) is formed as shown in FIG.

After that, the aluminum layer (5) was etched and removed and patterned by using the resist pattern (6A) as a mask to form a wiring layer made of aluminum.

[0005]

However, the above-mentioned conventional method has the following problems. That is, when the resist film (6) is exposed, a step is formed in the aluminum layer (5) due to the selective oxide film (2) and the polysilicon gate (3) being formed. This step difference becomes relatively large with miniaturization.

Due to this step, the resist pattern (6
In the exposure step for forming A), as shown in FIG. 8, due to diffuse reflection of exposure light on the surface of the aluminum layer (5) (this phenomenon is referred to as halation below), exposure in the resist film (6) is performed. Since the state becomes non-uniform, the shape of the resist pattern (6A) becomes non-uniform so that a desired shape as an etching mask cannot be obtained, as shown in FIG.

Therefore, by etching the aluminum layer (5) using the resist pattern (6A) having such a nonuniform shape as a mask, the nonuniform pattern is transferred onto the aluminum layer (5). The problem is that it is not possible to form an aluminum wiring having the correct size, or in some cases, a disconnection or a state close to that occurs, which causes a great problem in reliability of the aluminum wiring.

Therefore, countermeasures against halation such as exposure using a resist containing a light absorber have been taken, but this alone is still insufficient, and the adverse effects of halation cannot be completely suppressed. . Also, Ti
The anti-reflection film such as N film or amorphous silicon film was formed on the aluminum layer to suppress the effect of halation, but a sputtering device for film deposition is required to do this. As it requires special equipment, it was not easy to implement.

[0009]

The present invention has been made in view of the above-mentioned conventional drawbacks. As shown in FIGS. 1 to 4, a selective oxide film (10B), a wiring layer ( 10
C) is sequentially formed, and then an interlayer insulating film (10
D), a step of sequentially forming an aluminum layer (11),
Forming a nitride film (12) on the aluminum layer (11) and then forming a light absorber containing resist film (13) on the nitride film (12); and the light absorber containing resist film (13). ), Exposing the desired region of the above) to form a resist pattern (13A) by development, and etching the nitride film (12) and the aluminum layer (11) using the resist pattern (13A) as a mask. By removing and forming the wiring layer (11A), the adverse effect of halation due to the step of the highly reflective film such as an aluminum film can be suppressed and the desired shape can be easily obtained by using the existing equipment. The present invention provides a method of manufacturing a semiconductor device, which enables the formation of the wiring layer.

[0010]

[Operation] According to the method for manufacturing a semiconductor device of the present invention, as shown in FIGS.
After forming a nitride film (12) on the
2) A light absorber containing resist film (13) is formed on the resist film, and a desired region of the light absorber containing resist film (13) is exposed and then developed to form a resist pattern (13A). ) As a mask and the nitride film (1
2) and the aluminum layer (11) are etched and removed to form a wiring layer (11A).

Therefore, the light-absorbing agent-containing resist film (13)
By setting the film thickness of the nitride film (12) which is the underlayer film to an appropriate film thickness, the reflectance on the surface of the underlayer film is considerably reduced, so that the reflected light of the underlayer film is the main cause. It is possible to suppress the adverse effect of halation in the exposure step of the light absorber-containing resist film (13) to a considerable extent.

Thereby, the resist pattern (13A)
Has a slightly non-uniform shape due to the effect of slight halation, but the effect is slight and the nitride film (12
A pattern having a high processing dimension is transferred to the aluminum layer (11) of the base film in A) so that the wiring layer (11A) has a good shape and a high processing dimension accuracy.
Can be formed.

Further, unlike the measures for forming the antireflection film such as the TiN film and the amorphous silicon film on the aluminum layer, the above effect can be obtained without requiring special equipment such as a sputtering device for film deposition. Therefore, there is also an advantage that it can be easily implemented with existing equipment.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method of manufacturing a semiconductor device according to an embodiment of the present invention will be described below with reference to the drawings. First,
As shown in FIG. 1, after a selective oxide film (10B) for element isolation is formed on a Si substrate (10A) by a LOCOS method, a polysilicon layer is formed thereon and patterned to form a polysilicon gate ( 10C), and a BPSG film (10D) to be an interlayer insulating film is formed thereon, and then an aluminum layer (1
1) is formed by the sputtering method.

Next, a nitride film (12) having a film thickness of 400 Å is formed on the aluminum layer (11) with an HF (High Frequency) power of 0.32 kW and an LF (Low Frequency) power of 0.
Under the conditions of 48 kW, pressure of 2.6 Torr, and temperature of 400 ° C, SiH4 with a flow rate of 300 cc / min and N with a flow rate of 1000 cc / min.
2, plasma CVD using NH3 with a flow rate of 1900cc / min
And a photoresist film containing a light absorbing agent is applied to the entire surface by a method including a light absorbing agent of about 1 μm.
3) is formed.

Then, as shown in FIG. 2, the photomask (14) is used as a mask to expose a desired region of the light-absorbing agent-containing resist film (13) using g-line having a wavelength λ = 435 nm. Next, the light-absorbing agent-containing resist film (13) is developed and the exposed region is removed to form a resist pattern (13A) as shown in FIG.

In the above-mentioned exposure step, the reflectance of the base film of the light-absorbing agent-containing resist film (13) is reduced to 74% because the nitride film (12) having a film thickness of 400 Å is formed. FIG. 5 and FIG. 6 show the basis of this fact, that is, the nitride film (1
2) An example of computer simulation results showing the relationship between the reflectance on the surface and the film thickness of the nitride film (12) is shown. Here, the exposure light uses the i-line (λ = 356 nm) and the g-line (λ = 435 nm), respectively.

In the exposure using the g-line, when the nitride film (12) was not present (film thickness = 0), the reflectance was about 92%, which was considerably high. For example 400Å
It is shown in FIG. 6 that it can be reduced to about 74% by setting it to about 1450Å.
Further, in the exposure using the i-line, when the nitride film (12) was not present (film thickness = 0), the reflectance was about 92%, and the film thickness of the nitride film (12) was 300 Å. It is shown in FIG. 7 that it can be reduced to about 74% by setting it to about 1150Å.

As described above, the reflectance on the surface can be reduced by adjusting the film thickness of the nitride film (12). Therefore, the resist film containing a light absorber due to halation caused by reflected light. The adverse effect on exposure of (13) can be reduced to a considerable extent. Then, as shown in FIG. 3, using the resist pattern (13A) formed through the above steps as a mask, the flow rate of 180 SCCM of SiCl
4 gas, Cl2 gas with a flow rate of 23 SCCM, and He gas with a flow rate of 20 SCCM are used to etch and remove the nitride film 12 under the conditions of RF power of 1.3 kW and pressure of 15 Pa to perform patterning.

Next, as shown in FIG. 4, etching is continued under the above conditions, the aluminum layer (11) is etched and removed, and patterning is performed, whereby the wiring layer (1
1A) is formed. In the above-mentioned etching process, the resist pattern (13A) made of the light-absorbing agent-containing resist film (13) whose adverse effect on exposure due to halation has been reduced as much as possible is used as a mask for etching. Since the pattern defect due to is slight, the nitride film (12A)
On the aluminum layer (11) of the underlayer film, a pattern having a high processing dimension is transferred to the extent that there is no actual damage,
Wiring layer (11A) with good shape and high processing dimension accuracy
Can be formed.

Further, unlike the measures for forming the antireflection film such as the TiN film and the amorphous silicon film on the aluminum layer, the above effects can be obtained without requiring special equipment such as a sputtering device for film deposition. Therefore, there is also an advantage that it can be easily implemented with existing equipment. The above computer simulation method will be briefly described. In this method, the refractive index, the absorption coefficient and the film thickness of the nitride film (12), the aluminum layer (11) and the like are taken into consideration, and it is based on the simulation model described in detail in the following documents.

By PH Berning: “Theory and calculati
on of Optical Thin Films ”, Physics of Thin Films,
Vol-1, George Hass ed., New York; Academic Press (196
3) pp.69-121: In this embodiment, g-line is used as the exposure light of the light-absorbing agent-containing resist film (13), but the present invention is not limited to this, and i-line, excimer laser, etc. Even if used, the same effect can be obtained.

Furthermore, in the present embodiment, the nitride film (12) and the aluminum layer (11) are simultaneously etched under the same etching conditions using the resist pattern (13A) as a mask, but the present invention is not limited to this, and for example, After patterning the nitride film (12), the resist pattern (13A) and the patterned nitride film (12) are used as masks to etch the aluminum layer (11) under different conditions to perform patterning. Produce the effect of.

[0024]

As described above, after the nitride film (12) is formed on the aluminum layer (11), the light absorber-containing resist film (13) is formed on the nitride film (12). After exposing a desired region of the light absorbing agent-containing resist film (13), it is developed to form a resist pattern (13A), and the resist pattern (13A) is used as a mask to form a nitride film (12) and an aluminum layer (11). Etching
After removal, the wiring layer (11A) is formed.

Therefore, the light-absorbing agent-containing resist film (13)
By adjusting the film thickness of the nitride film (12) which is the underlayer film of (1) to an appropriate film thickness, the aluminum layer (1) below the nitride film (12) in the exposure step of the resist film containing a light absorber (13) is
The adverse effect of halation due to the reflected light from 1) can be suppressed to a large extent. As a result, a pattern having a high processing dimension is transferred to the aluminum layer (11) so as not to cause actual damage, so that the wiring layer (11A) having a good shape and a high processing dimension accuracy can be formed. .

Further, like the measures for forming the antireflection film such as the TiN film and the amorphous silicon film on the aluminum layer, the above effect can be obtained without requiring special equipment such as a sputtering device for film deposition. Therefore, there is also an advantage that it can be easily implemented with existing equipment.

[Brief description of drawings]

FIG. 1 is a first cross-sectional view illustrating a method of manufacturing a semiconductor device according to an embodiment of the invention.

FIG. 2 is a second cross-sectional view illustrating the method for manufacturing the semiconductor device according to the embodiment of the invention.

FIG. 3 is a third cross-sectional view illustrating the method for manufacturing the semiconductor device according to the embodiment of the invention.

FIG. 4 is a fourth sectional view illustrating the method for manufacturing the semiconductor device according to the embodiment of the invention.

FIG. 5 is a first graph showing a result of a computer simulation for explaining the function and effect of the present invention.

FIG. 6 is a second graph showing the result of a computer simulation for explaining the function and effect of the present invention.

FIG. 7 is a first cross-sectional view illustrating the method for manufacturing the semiconductor device according to the conventional example.

FIG. 8 is a second cross-sectional view illustrating the method for manufacturing the semiconductor device according to the conventional example.

Claims (2)

[Claims] 1. A selective oxide film (10) on a substrate (10A).
B), a wiring layer (10C) are sequentially formed, and then an interlayer insulating film (10D) and an aluminum layer (11) are sequentially formed thereon, and a nitride film (12) is formed on the aluminum layer (11). ) Is formed, and then a light absorber-containing resist film (13) is formed on the nitride film (12), and a desired region of the light absorber-containing resist film (13) is exposed and then developed. Forming a resist pattern (13A) by etching, and using the resist pattern (13A) as a mask, the nitride film (12) and the aluminum layer (11) are etched and removed to form a wiring layer (11A). A method of manufacturing a semiconductor device, comprising: 2. A selective oxide film (10) on a substrate (10A).
B), a wiring layer (10C) are sequentially formed, and then an interlayer insulating film (10D) and an aluminum layer (11) are sequentially formed thereon, and a nitride film (12) is formed on the aluminum layer (11). ) Is formed, and then a light absorber-containing resist film (13) is formed on the nitride film (12), and a desired region of the light absorber-containing resist film (13) is exposed and then developed. Forming a resist pattern (13A) using the resist pattern (13A) as a mask and etching and removing the nitride film (12) to perform patterning; and the resist pattern (13A) and the patterned nitride film. The aluminum layer (11) is etched and removed using (12A) as a mask to form a wiring layer (11
A) is formed, and the manufacturing method of the semiconductor device characterized by the above-mentioned.