JPH0831710A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To prevent the generation of particles due to the peeling of a film from the peripheral section of a wafer, and to obviate heavy-metal contamination and the generation of a crystal defect in the wafer. CONSTITUTION:The upper section of a first silicon oxide film 2 formed on a silicon substrate 1 is coated with a first positive type photo-resist film 6, the first positive type photo-resist film 6 is developed through pattern exposure and peripheral exposure to form a pattern, the first silicon oxide film 2 is etched selectively, and the end section of the first silicon oxide film 2 is formed so as to be separated from the end section of the silicon substrate 1 by W1. The first positive type photo-resist film 6 is removed. The same process is carried out regarding a tungsten polycide film 3 and a second positive type photo-resist film 7, a second silicon oxide film 4 and a third positive type photo- resist film 8, and a polysilicon film 5 and a fourth positive type photo-resist film 9, and the end sections of each film 3, 4, 5 are formed so as to be separated from the end section of the silicon substrate 1 by W2, W3, W4 in succession. Films having inferior adhesion are not brought into contact mutually and directly in the peripheral region of a wafer.

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 manufacturing a semiconductor device including a photoresist process for processing an end portion of a film formed on a peripheral portion of a wafer.

[0002]

2. Description of the Related Art A conventional photoresist process for a semiconductor device will be described with reference to FIG. FIG. 2A is a plan view of a wafer for explaining a film peeling phenomenon that occurs in a conventional photoresist process, and FIG. 2B is an enlarged plan view of a portion E of FIG. 2A.

As shown in FIG. 2, in the conventional etching process of the peripheral portion A of the wafer D and the like, it is prevented that the photoresist film on the peripheral portion A of the wafer D is peeled off by contact with a clamp such as an etching device to become particles. In order to
Before the development process in the photolithography process, exposure for removing the peripheral portion A of the wafer is performed, and the photoresist film on the peripheral portion A of the wafer is removed by the development.

Normally, in the manufacturing process of a semiconductor device, the photolithography process and the etching process are repeated ten times or more.
In performing the peripheral exposure of the wafer peripheral portion A, since the positional accuracy is about several tens of μm, the edge shifts in a number of steps as shown in FIG. 2B.

Further, in the method of manufacturing a semiconductor device described in Japanese Patent Application Laid-Open No. 2-142115, in which each of a plurality of films is edge-peeled through a photoresist process,
In the photoresist process, the edge peel width of the film formed in the next step is narrower than the edge peel width of the film formed in the previous step, and the edge of the film formed in the previous step is formed in the next step. The exposure width was changed so as to cover the edge of the film.

[0006]

Conventionally, due to the deviation of the edge position of the peripheral exposure, the films having poor adhesion are contacted with each other in a width of 10 μm or more at the peripheral portion of the wafer, and film peeling occurs to generate particles. There was a problem.

For example, FIG. 2A shows an LSI on a wafer D.
It shows how the chip array is patterned. In FIG. 2A, what is arranged in the LSI chip area B in a grid pattern is an LSI chip. The line immediately inside the edge of the wafer D is the edge area A.
Further, FIG. 2B is an enlarged plan view of the E portion of the edge area A.

In FIG. 2A, the LSI chip area B
In the region between the edge region A and the edge region A, the photoresist film is always entirely left before etching. Therefore, the film formed in that region is not etched and the film is finally left. Further, the peripheral exposure is performed at a certain distance from the edge of the wafer D. For example, if the wafer diameter is 15
If it is 0 mm, the area outside the circle having a diameter of 144 mm centering on the wafer center is peripherally exposed. However,
Since the positional accuracy of the exposure accompanying this peripheral exposure is on the order of several tens of μm, as shown in FIG. 2B, the position of the edge of each film remaining after each etching step differs depending on each film. come.

In the conventional method of manufacturing a semiconductor device, as shown in the longitudinal sectional view of the main part of FIG. 3, each layer (first silicon oxide film 2, tungsten polycide 2) formed on the silicon substrate 1 is formed. Film 3, second silicon oxide film 4,
In the photoresist process of the polysilicon film 5), unnecessary resist is likely to remain in the peripheral portion of the wafer. The exposure is performed with high strength and a constant width so that unnecessary resist does not remain in the peripheral portion of the wafer. At that time, the tungsten polycide film 3 and the polysilicon film 5 may come into contact with each other in the peripheral portion of the wafer due to an error in peripheral exposure.

According to an experiment conducted by the present inventor, when the polysilicon film 5 is formed on the tungsten polycide film 3 and brought into contact with it, it is 10 μm × 10 μm or more in one region.
It was found that the polysilicon film 5 on the tungsten polycide film 3 was easily peeled off. There is a problem in that the region C of the polysilicon film 5 on the tungsten polycide film 3 shown in FIG. 3 is peeled off and scattered in the wafer to form particles, which in turn lowers the yield of LSI manufacturing.

Further, in the one disclosed in Japanese Patent Laid-Open No. 2-142115, the photoresist process is sequentially performed so that the film of the previous process is covered with the film of the next process. However, when a metal film such as a tungsten film or a tungsten silicon film or an insulating film such as a silicon nitride film is brought into contact with the semiconductor substrate, there is a problem that heavy metal contamination or crystal defect occurs in the semiconductor substrate, which results in a leakage current. was there.

Therefore, an object of the present invention is to provide a method of manufacturing a semiconductor device capable of preventing the generation of particles from the peripheral portion of a wafer by controlling the edge of peripheral exposure of the wafer. A further object of the present invention is to provide a method for manufacturing a semiconductor device in which heavy metal contamination and crystal defects do not occur in a semiconductor substrate due to peripheral exposure of a wafer.

[0013]

In order to achieve the above object, the present invention provides a method of manufacturing a semiconductor device including a step of depositing a plurality of films on a peripheral region of a wafer, at least on the peripheral region of the wafer. After forming the first film, a first step of removing the first film from the edge of the wafer toward the inside of the wafer to a first predetermined position; and, after the first step,
After forming the second film on at least the first film, the second film is formed from the edge of the wafer toward the inside of the wafer to a second predetermined position inside the first position. And a second step of removing.

[0014]

In the method of manufacturing a semiconductor device in which each of a plurality of films is edge-peeled through the photoresist process, in the photoresist process, the edge width of the film formed in the preceding process (from the edge of the wafer to the preceding process is formed). The width of the edge of the film formed in the next step (the width from the edge of the wafer to the edge of the film formed in the next step) should be wider than the width of the film formed in the next step). The peripheral exposure width of the wafer in each of the previous step and the next step is changed. Therefore, the edge of, for example, an oxide film formed on the tungsten polycide film is recessed inward from the edge of, for example, the tungsten polycide film in the previous step, and the edge of, for example, a polysilicon film formed on the oxide film is an oxide film. Since it is formed so as to be recessed inward from the edge, contamination of heavy metals such as tungsten and crystal defects due to a nitride film do not occur in the peripheral portion of the wafer. Further, there is no large area where the films having poor adhesion are in direct contact with each other. As a result, film peeling does not occur, which leads to LSI
It is possible to prevent the generation of particles that cause a decrease in yield during manufacturing.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a wafer edge exposure method according to the present invention will be described with reference to FIG. FIG. 1 is a vertical cross-sectional view of an essential part for explaining a wafer peripheral exposure method in this embodiment.

In FIG. 1A, a first silicon oxide film 2 is formed on a silicon substrate 1 by a thermal oxidation method to have a film thickness of 3000Å. Photolithography process or first
A first positive type photoresist film 6 is applied on the silicon oxide film 2 and the pattern exposure and the peripheral exposure are performed. afterwards,
The first positive photoresist film 6 is developed to form a pattern on the first positive photoresist film 6. afterwards,
The first silicon oxide film 2 is selectively etched. As a result, the end portion of the first silicon oxide film 2 is formed so as to be separated from the end portion of the silicon substrate 1 by W1. Then, the first positive photoresist film 6 is removed. Since the edge position accuracy of the peripheral exposure is ± 30 μm in the peripheral exposure method of the first positive type photoresist film 6, in order to sequentially expand the peripheral exposure region setting by 100 μm as the peripheral exposure is performed, Exposure is performed up to 2600 μm from the edge of the wafer.

Next, in FIG. 1B, a polysilicon film having a thickness of 1500 Å is formed on the silicon substrate 1 by the CVD method.
Then, the tungsten polycide film 3 having a total thickness of 3000 Å is formed by forming a tungsten silicide film having a thickness of 1500 Å on the first silicon oxide film 2 by sputtering. Silicon substrate 1,
After the second positive photoresist film 7 is applied on the first silicon oxide film 2 and the tungsten polycide film 3, pattern exposure, peripheral exposure is performed, and development is performed, the tungsten polycide film 3 is selectively etched. To do. as a result,
The end portion of the tungsten polycide film 3 is formed so as to be separated from the end portion of the silicon substrate 1 by a distance W2 which is further separated from W1. After the selective etching is completed, the second positive photoresist film 7 is removed. The peripheral exposure of the second positive photoresist film 7 is performed from the edge of the wafer to 2800 μm.

Next, in FIG. 1C, a second silicon oxide film 4 having a film thickness of 5000Å is formed on the tungsten polycide film 3 by the CVD method. Silicon substrate 1,
First silicon oxide film 2, tungsten polycide film 3
Then, a third positive photoresist film 8 is applied on the second silicon oxide film 4, pattern exposure and peripheral exposure are performed, and then development is performed. Then, the second silicon oxide film 4 is selectively etched. As a result, the second silicon oxide film 4
Is formed to be separated from the end of the silicon substrate 1 by a distance W3 which is farther than W2. After completion of the selective etching, the third positive type photoresist film 8 is removed. The peripheral exposure is performed up to 3000 μm from the edge of the wafer.

Next, as shown in FIG. 1D, a polysilicon film 5 having a thickness of 3000 Å is formed on the second silicon oxide film 4 by the CVD method. A fourth positive photoresist film 9 is applied on the silicon substrate 1, the first silicon oxide film 2, the tungsten polycide film 3, the second silicon oxide film 4 and the polysilicon film 5, and pattern exposure and peripheral exposure are performed. I do. Then, the fourth positive photoresist film 9 is developed to form a photoresist pattern. Then, the polysilicon film 5 is selectively etched. As a result, the end portion of the polysilicon film 5 is formed so as to be separated from the end portion of the silicon substrate 1 by a distance W4 which is farther than W3. After the selective etching is completed, the fourth positive photoresist film 9 is removed as shown in FIG. The peripheral exposure is performed up to 3200 μm from the edge of the wafer.

In the peripheral exposure method described above, the edge position accuracy of the peripheral exposure is ± 30 μm. Therefore, as the peripheral exposure is performed, the peripheral exposure region is sequentially set to 100 μm.
It was spread by m. That is, the peripheral exposure when patterning the first silicon oxide film 2 is performed 260 times from the wafer edge.
Set up to 0 μm. Subsequent peripheral exposure is performed by sequentially applying 2800 μm to the tungsten polycide film 3, and then performing second exposure.
The silicon oxide film 4 was set to 3000 μm, and the polysilicon film 5 was set to 3200 μm.

As a result, as shown in FIG. 1, the edges of the films 2, 3, 4, and 5 near the wafer edge are formed so as to be gradually separated from the wafer edge. The tungsten polycide film 3 and the polysilicon film 5 do not come into contact with each other in the peripheral region (edge region) of the wafer, and therefore, undesirable film peeling does not occur in the peripheral region of the wafer.

Further, in the above embodiment, the first silicon oxide film 2 and the second silicon oxide film 4 are replaced by a nitride film and an ONO film (a laminated film of an oxide film, a nitride film and an oxide film). May be.

In the above embodiment, the peripheral exposure is sequentially expanded from the wafer edge, and the manufacturing method in which the polysilicon film does not cover the tungsten polycide film has been described.
The manufacturing method of the present invention is not limited to the above film. Further, in the photoresist process, the case of using the positive type photoresist film is shown, but also in the case of using the negative type photoresist film, if the width relationship of the exposure width of the previous process and the next process is reversed, It is clear that the invention applies.

[0024]

As described above, according to the present invention,
Since it is possible to prevent unintentional contact between the films having poor adhesion at the peripheral exposure edge portion of the wafer, it is possible to suppress the generation of particles due to film peeling, and to prevent the occurrence of heavy metal contamination and crystal defects. And then L
It is possible to greatly improve the production yield of SI and the like.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a main part for explaining a wafer peripheral exposure method according to an embodiment of the present invention.

FIG. 2 illustrates a conventional wafer edge exposure method,
(A) is a plan view of a wafer, (b) is an enlarged plan view of an E portion of (a).

FIG. 3 is a vertical cross-sectional view of a main part for explaining a conventional method for manufacturing a semiconductor device.

[Explanation of symbols]

 1 Silicon Substrate 2 First Silicon Oxide Film 3 Tungsten Polycide Film 4 Second Silicon Oxide Film 5 Polysilicon Film 6 First Positive Photoresist Film 7 Second Positive Photoresist Film 8 Third Positive Type Photoresist film 9 Fourth positive photoresist film

Claims (1)

[Claims] 1. A method of manufacturing a semiconductor device, comprising: depositing a plurality of films on a peripheral region of a wafer; forming a first film on at least a peripheral region of the wafer; A first step of removing the first film toward a first predetermined position toward the inside, and after forming the second film at least on the first film after the first step, A second step of removing the second film from the end portion toward the inside of the wafer to a second predetermined position inside the first position, the second step of removing the second film. Production method.