JP2003027228A - Semiconductor device manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technology capable of preventing any abnormal discharge occurring during a sputtering process in manufacturing a semiconductor device, and reducing the generation of foreign matters. SOLUTION: A chamfered part of an outer peripheral part of a sputter target used in the sputtering process in manufacturing the semiconductor device is formed into a smoothly curved surface.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique effectively applied to a sputtering process in a semiconductor device manufacturing method.

[0002]

2. Description of the Related Art In a sputtering process in a method of manufacturing a semiconductor device, heavy charged particles such as Ar cations are applied to a sputter target, and the particles ejected from the sputter target due to the impact thereof are attached to a facing sample. It is a thing.

As shown in FIG. 5, the conventional sputter target has a chamfered outer peripheral edge.

[0004]

[Problems to be Solved by the Invention] The sputtering process is
As described above, the cations of Ar or the like are irradiated to the sputter target, and the particles ejected from the sputter target by the impact are attached to the facing sample, but not all the particles ejected from the sputter target. However, it does not adhere to the sample, but some particles return to the sputter target and adhere again to form a film.

Further, heat is generated in the sputter target by irradiating Ar cations, and this heat causes stress in the sputter target due to thermal expansion.

This stress is concentrated especially in the angular portion of the chamfered portion of the sputter target. Therefore, if the film of particles described above is formed in the angular portion, the film peels off, flips up, and abnormal discharge occurs. Induce.

Due to this abnormal discharge, there is a problem in that particles (hereinafter referred to as "foreign matter") having a size different from that of sputtered particles are generated.

An object of the present invention is to provide a technique capable of preventing abnormal discharge that occurs during a sputtering process in manufacturing semiconductor devices and reducing the generation of foreign matter.

The above and other objects and novel features of the present invention will be apparent from the description of this specification and the accompanying drawings.

[0010]

Among the inventions disclosed in the present application, a brief description will be given to the outline of typical ones.
It is as follows.

According to the present invention, a sputter target including a sputter material having a first main surface and a second main surface and a backing plate joined to the first main surface of the sputter material is prepared. A method of manufacturing a semiconductor device, comprising the steps of placing semiconductor wafers facing each other and adhering particles of a sputter target to the main surface of the semiconductor wafer, wherein the sputtered material has the first main surface exposed at its outer peripheral portion. So that the reattachment particles to the sputter target are not separated by stress on the outer peripheral side surface between the first main surface and the second main surface. It is characterized by being applied.

The present invention also provides a step of preparing a sputter target including a sputter material having a first main surface and a second main surface, and a backing plate bonded to the first main surface of the sputter material, and a sputtering apparatus. Inside, and a step of forming a thin film on the semiconductor wafer by placing a semiconductor wafer facing the second main surface of the sputter target, wherein the sputter material has an outer periphery thereof. Part of the outer surface of the outer peripheral portion between the first main surface and the second main surface is adhered to the backing plate so that the first main surface of the sputter target is not exposed. In the step of forming the thin film, a direct-current electric field or a high-frequency electric field is applied to the sputter target so that the surface is processed so as not to peel. It is characterized in that the sputtering process.

(Operation) According to the above-mentioned means, the chamfered portion of the outer peripheral portion of the sputtering target used in the sputtering process is processed into a smooth curve, and a DC electric field or a high frequency electric field is applied to the processed sputtering target, Since sputtering is performed, particles that fly out due to the application of an electric field are reattached to the chamfered portion of the outer peripheral portion of the sputter target, and even if a film is formed, the chamfered portion of the outer peripheral portion of the sputter target is processed into a smooth curve. It is possible to prevent concentration of stress generated by thermal expansion of the sputter target.

Therefore, it is possible to prevent film peeling and reduce the generation of foreign matter that occur during the sputtering process.

The structure of the present invention will be described below together with the embodiments.

In all the drawings for explaining the embodiments, parts having the same function are designated by the same reference numerals, and the repeated description thereof will be omitted.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (Embodiment) FIG. 1 is an enlarged view of an outer peripheral portion of a sputter target, which is a reference example of the present invention, to show characteristics of the outer peripheral portion. In FIG. 1, 1 is a sputter target and 2 is a backing plate. The material of the sputter target 1 is, for example, TiW, and its dimensions are as follows. D1 shown in FIG.
Is preferably set to a value that does not exceed 9 mm from the outer circumference, and is 8 mm here. D2 is 6.35 ± 0.
1 mm and D3 is 324 ± 0.2 mm. R1
Is a curved surface processing with a radius such that there is no angular portion and smoothly connecting, and R2 is a curved surface processing with a radius of 2.0 mm.

Next, an embodiment of the present invention is shown in FIG.
FIG. 2 is an enlarged view of the outer peripheral portion for showing the characteristics of the outer peripheral portion of the sputter target according to the embodiment of the present invention.
As is apparent from the drawing, the sputter target in FIG. 2 is formed by joining the sputter material to a backing plate so that the first main surface (lower surface) of the outer peripheral portion of the sputter material is not exposed.
The first main surface and the second main surface (upper surface opposite to the first main surface)
In the side surface of the outer peripheral portion between and, the surface processing is performed so as to prevent reattachment particles to the sputter target from being separated by stress, that is, processed into a fan shape. Is 8 mm, D2 is 6.35 ± 0.1 mm, D3 is 324 ± 0.2 m
m. According to the present embodiment, as is apparent from the figure, since the first main surface (lower surface) is joined to the backing plate so as not to be exposed, the outer peripheral side that is in contact with the second main surface (upper surface) side is gentle. In order to prevent re-adhesion particles on the sputter target from peeling due to stress.

FIG. 3 shows an example of a processing method for forming a curved surface into the shape of the sputter target of each embodiment. In FIG. 3, 1 indicates a sputter target and 3 indicates a grindstone. In the processing method shown in FIG. 3, the grindstone 3 is rotated to move the sputter target up and down to smooth the outer peripheral portion.

The processing method for processing the shape of the sputter target is not limited to this, and the sputter target material may be fitted into the mold to obtain a sputter target having a smooth outer peripheral portion.

Next, a method for forming a conductive film on a semiconductor wafer using the sputter target of the present invention will be briefly described.

First, TiW is used as a sputter target material for forming a conductive film, and the chamfered portion of the outer peripheral portion is curved to be the shape of the sputter target of the present embodiment shown in FIG. 1 using a grindstone 3 shown in FIG. To do.

Then, the curved sputter target is placed on the cathode, and the semiconductor wafer to be sputtered is placed on the anode so as to face each other. Ar cations are injected between the cathode and the anode, and a DC voltage is applied to the cathode. Apply.

As a result, plasma is generated between the pair of electrodes, the sputtering target placed on the cathode is repelled by the ions in the plasma, and a conductive film is formed on the semiconductor wafer placed on the opposing anode.

Next, the numbers of foreign substances when the sputtering target of the present embodiment shown in FIG. 1 and the conventional sputtering target are mounted and sputtering is performed will be compared.

FIG. 4 is a diagram showing the number of foreign particles per power consumption when the sputtering target of the present embodiment and the conventional sputtering target are mounted in a sputtering apparatus and sputtering is performed. In this test, a known sputtering device was used, and TiW was used as the sputtering target material. In FIG. 4, the horizontal axis represents cumulative power consumption (KWH), and the vertical axis represents the number of foreign matters. Further, the broken line in FIG. 4 indicates the conventional sputter target, and the solid line indicates the sputter target of the present embodiment.

In the conventional sputter target shown by the broken line in FIG. 4, a sudden increase in the number of foreign particles was observed,
There is evidence of abnormal discharge.

On the other hand, the sputter target of this embodiment has a small number of foreign matters in general and is stable, and no sudden increase in the number of foreign matters is observed until the cumulative power consumption exceeds 200 KWH.

That is, it is understood from FIG. 4 that the sputtering target of the present embodiment can prevent abnormal discharge during the sputtering process and reduce the number of foreign matters.

As described above, by eliminating and smoothing the chamfered portion of the chamfered portion of the outer peripheral portion of the sputter target, there is no chamfered portion even if stress due to thermal expansion is generated by heat generated in the sputter target. There is no place where stress concentrates.

Therefore, even if particles that have jumped out of the sputter target during the sputter process in the manufacture of a semiconductor device adhere to the sputter target again to form a film, there is no place where stress concentrates, so the film peels off. It does not turn up, abnormal discharge can be prevented, and foreign matter can be reduced.

The inventions made by the present inventors are as follows.
Although the specific description has been given based on the above-described embodiment, the present invention is not limited to the above-described embodiment, and it goes without saying that various modifications can be made without departing from the scope of the invention.

[0033]

The effects obtained by the typical ones of the inventions disclosed in the present application will be briefly described as follows.

By eliminating the angular portion of the chamfered portion on the outer peripheral portion of the sputter target and making it smooth,
Even if stress due to thermal expansion is generated by the heat generated in the sputter target, there is no angular portion, so there is no place where the stress concentrates. Even if a film is formed by adhering to the film, there is no place where stress is concentrated, so that the film does not peel off and flip up, abnormal discharge can be prevented, and the generation of foreign matter can be reduced.

[Brief description of drawings]

FIG. 1 is an enlarged view of an outer peripheral portion for explaining a shape of an outer peripheral portion of a sputter target which is a reference example of the present invention.

FIG. 2 is an enlarged view of the outer peripheral portion for explaining the shape of the outer peripheral portion of the sputter target according to the embodiment of the present invention.

FIG. 3 is a diagram showing an example of a processing method for processing the outer peripheral portion of the sputter target into a curved surface.

FIG. 4 is a diagram showing the number of foreign particles per power consumption when the sputtering target is mounted on each of the sputtering target of the present embodiment and the conventional sputtering target.

FIG. 5 is an enlarged view of an outer peripheral portion for explaining the shape of the outer peripheral portion of a conventional sputter target.

[Explanation of symbols]

1 ... Sputter target, 2 ... Backing plate, 3
… Whetstone.

Claims (3)

[Claims] 1. A sputter target including a sputter material having a first main surface and a second main surface and a backing plate bonded to the first main surface of the sputter material is prepared and is opposed to the second main surface. A semiconductor wafer, and a method of manufacturing a semiconductor device, comprising the steps of depositing particles of a sputtering target on a main surface of the semiconductor wafer, wherein the sputtered material does not expose the first main surface in an outer peripheral portion thereof. Is joined to the backing plate, and the outer peripheral side surface between the first main surface and the second main surface is provided with an inclined surface processing so that reattachment particles to the sputter target are not separated by stress. A method of manufacturing a semiconductor device, comprising: 2. A step of preparing a sputter target including a sputter material having a first main surface and a second main surface, and a backing plate bonded to the first main surface of the sputter material; A semiconductor wafer is placed facing the second main surface of the sputter target,
A method of manufacturing a semiconductor device, comprising: forming a thin film on the semiconductor wafer, wherein the sputtered material is bonded to the backing plate so that the first main surface at an outer peripheral portion of the sputtered material is not exposed. In the step of forming the thin film, the outer peripheral side surface between the first main surface and the second main surface is subjected to surface processing with an inclination so that reattachment particles to the sputtering target are not separated by stress. A method of manufacturing a semiconductor device, which comprises applying a DC electric field or a high frequency electric field to the sputtering target to perform sputtering. 3. The method of manufacturing a semiconductor device according to claim 1, wherein the backing plate has a thin portion separated from the first main surface of the sputter material.