JP2556205B2 - Method of manufacturing semiconductor device related to sputtering - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sputtering process used for manufacturing a semiconductor device, and more particularly to suppressing peeling of a film adhered to a shield provided around a sputtering space.

Those skilled in the art are familiar with the principles or embodiments of the sputtering process used in the manufacture of semiconductor devices. In the sputtering process, if the spatter material scattered from the target adheres to the inner wall of the processing equipment,
Since it becomes difficult to remove it, it is also a normal specification of the device configuration to provide an isolation wall called a shield for the purpose of preventing adhesion to the inner wall.

[0003]

2. Description of the Related Art FIG. 3 is a diagram schematically showing a sectional structure of a plasma sputtering apparatus provided with a shield. Hereinafter, this drawing will be referred to.

Reference numeral 1 denotes an airtight chamber, and when plasma generated in the plasma generation space 2 collides with the target 3, the target constituent material is smashed into fine droplets and is ejected. (Usually a semiconductor wafer)
Deposited on top of.

At this time, since the directions of the splashes are all in the direction of the target surface side, a considerable amount will also come to the inner wall surface of the chamber. If this is adhered to the inner wall surface as it is, the maintenance work of the apparatus becomes difficult. Therefore, as shown in the figure, the shield 5 is provided to prevent sputtering deposition on the inner wall surface of the chamber. Since the shield can be removed, the deposit can be removed relatively easily. Reference numeral 6 is a clamper for fixing the wafer, and here the shield has a structure which also serves as a wafer support.

[0006]

In the manufacture of semiconductor devices, the physical characteristics of the film deposited by sputtering are often severe due to the requirements of device design. Therefore, the processing conditions for sputtering are set with the film quality of the formed film as the top priority.

For example, titanium nitride (TiN) used as a barrier film for Al / Ti wiring is usually formed by sputtering. At that time, FIG. 2 shows how the internal stress and composition of the deposited layer change depending on the processing conditions.

This graph shows N ₂ which is a plasma source gas.
It expresses the stress and composition of the generated film with respect to the supply rate of
Tensile stress is positive and compressive stress is negative. Gas pressure is N
_{2 When the} feed rate is 120 sccm or less, it is 4 mTorr, and when it is higher than that, it increases in proportion to the feed rate. At 200 sccm, it is 6 mTorr and 300 sccm.
It is 8 mTorr.

If the TiN film is used as a barrier film for a metal wiring film, it is desirable that its resistivity be as low as possible, and for that purpose, the composition must be brought close to the stoichiometric ratio. Therefore, according to the data in FIG. 2, the N ₂ supply rate is set to 150 sccm to 200 sccm. However, under this condition, the compressive stress exceeding 10 ¹⁰ dyne / cm ² is included in the sedimentary layer.

Although it is not preferable that the coatings formed on the wafer contain either compressive or tensile stress, the coatings may be subdivided by patterning,
As a result of being subjected to a treatment such as being laminated with a coating film containing different kinds of stress, the internal stress is often relaxed as a whole to such an extent that it does not matter.

However, the situation is different from that of the processing device. In a normal sputtering apparatus, wafers are processed one by one, so even if only one lot of wafers is processed, sputtering is performed 20 to 40 times, and a thick sputtering film is deposited on the shield. When the film thickness increases and the stress of the film increases and exceeds the adhesive force to the shield, the adhered film may peel off and the fragments may scatter into the processing space. The peeled pieces thus generated are dust and adhere to the surface of the wafer, which hinders the good formation of elements.

An object of the present invention is to provide a sputtering treatment method in which the generation of peeled pieces of this kind is suppressed.
Accordingly, it is to provide a method for manufacturing a semiconductor device with an improved manufacturing yield.

[0013]

To achieve the above object, according to an aspect of, the present invention, the method of manufacturing a semiconductor device performed by using a scan sputtering apparatus shield surrounds the space where sputtering processing is performed are provided In the first test under the condition that a deposited layer having a desired film quality is deposited and formed on the sample surface.
After performing the first sputtering treatment on the material,
Removing the first sample from the processing space ;
The sample is loaded into the processing space and is placed in front of the second sample.
Note First sputtering treatment or the first sputtering
Deposited layer containing the same stress as the deposited layer by the ring process
And a step of performing a second sputtering treatment to form
Seen, before loading the second sample to the processing space, before
The film deposited by the first sputtering process is included.
A film containing a stress whose direction of action is opposite to that of the stress
Includes a step of performing a third sputtering treatment under the condition that is attached to the shield surface .

In a typical embodiment of the present invention,
The film attached to the shield surface by the first sputtering contains a compressive stress, and the film attached to the shield surface by the second sputtering contains a tensile stress.

FIG. 1 is a flow chart showing the above-mentioned process which is a feature of the present invention. After the sputtering of a predetermined number of wafers is performed, the sputtering of the regular wafer is interrupted and the strain relaxation sputtering using the dummy wafer is performed. I do. The deposited layer formed by the strain relaxation sputtering contains a stress having an action direction opposite to the stress contained in the deposited layer formed by the original sputtering process, and cancels the internal stress of the shield surface adhesion film. Then, the sputtering of the regular wafer is started again.

[0016]

By the sputtering performed for the purpose of forming the deposited layer on the wafer, the adhered film containing the compressive stress is formed on the shield surface.
Since a layer with tensile stress is deposited and formed subsequently,
The internal stress of the film that adheres to the shield cancels each other out and becomes weak.

If the internal stress is reduced, peeling due to it is less likely to occur, and the generation of dust that hinders element formation is eliminated. It should be noted from the graph of FIG. 2 that when the sputtering is performed by the same apparatus, the stresses contained in the deposited layer can be made different by selecting the processing conditions.

[0018]

EXAMPLE It is common practice to form the structure shown schematically in FIG. 4 in the device region within an integrated circuit,
The formation of the TiN film included in the figure will be described as an example. In the figure, 10 is a Si substrate, 11 is an insulating film such as SiO ₂ , 12 is a Ti film of 100 to 500Å, 13 is Ti of 1000 to 2000Å.
N film, 14 is an Al layer of 3000 to 10000Å.

The sputtering apparatus used is that shown in FIG. 3, and the gas containing 40 to 60% of N ₂ in Ar is 1.
It is supplied at a pressure of 0 to 4.0 mTorr, and this is turned into plasma and T
The i target is hit to perform sputtering. After the TiN film having a predetermined thickness is deposited on the Si wafer on which the integrated circuit is formed, the wafer is replaced and the same process is performed. By this sputtering, a TiN film containing a compressive stress adheres to the shield.

After performing sputtering on several wafers to one lot of Si wafers, dummy wafers are set and N ₂ 100
%, The pressure is 10 mTorr, and the processing conditions are changed to perform sputtering. The processing time is set to several times to ten times that for depositing a TiN film on a regular wafer, and a TiN film containing a tensile stress is formed on the shield to a sufficient thickness.

When the processing on the dummy wafer is completed, a regular wafer is set again, the processing conditions are returned to the original state, and the Ti
The sputtering formation of the N film is continued. Since the internal stress of the TiN film attached to the shield is weakened, it does not peel off and become dust.

The sputtered deposited layer often contains a compressive or tensile stress, and its action direction is generally reversed by changing the treatment conditions. Therefore, the sputtered deposited layer is not limited to the above TiN, but other types of coatings. The present invention can be applied to the sputtering formation of to prevent peeling of the adhered film.

[0023]

As described above, according to the present invention, compression is performed.
After advancing the formation of a film containing (or tensile) stress to some extent, a film containing tensile (or compression) stress is formed on the shield to relieve the internal stress of the shield surface adhesion film, so the adhesion film peels off. Scattering is significantly reduced, and it does not fall as dust on the wafer. Therefore, the generation of defective elements in the integrated circuit is suppressed, and the manufacturing yield of the integrated circuit device is improved.

[Brief description of drawings]

FIG. 1 is a process diagram showing a processing order of the present invention.

FIG. 2 is a diagram showing a relationship between processing conditions and stress in a formed film.

FIG. 3 is a schematic diagram showing the structure of a sputtering apparatus.

FIG. 4 is a diagram showing a structure of an element formed in an example.

[Explanation of symbols]

1 chamber 2 plasma generation space 3 target 4 sample (wafer) 5 shield 6 clamper 10 Si substrate 11 insulating film (SiO ₂ ) 12 Ti film 13 TiN film 14 Al layer

Claims (2)

(57) [Claims] 1. A method for manufacturing a semiconductor device, which is performed by using a sputtering apparatus having a shield surrounding a space where a sputtering process is performed, wherein a deposition layer having a desired film quality is deposited and formed on a sample surface. The first sputtering process is performed on the first sample under the conditions
And then removing the first sample from the processing space
Then, the second sample is loaded into the processing space, and the second sample is
The first sputtering treatment or the first sputtering treatment.
Includes the same kind of stress as the deposited layer by the putting process
A step of performing a second sputtering process for forming a deposited layer
And before loading the second sample into the processing space.
The film deposited by the sputtering process of No. 1 is included
The direction of action is opposite to that of stress.
The third sputtering treatment is performed under the condition that it adheres to the shield surface.
A method of manufacturing a semiconductor device, comprising: 2. The method for manufacturing a semiconductor device according to claim 1, wherein the film deposited on the shield surface by the first sputtering contains compressive stress, and the film deposited on the shield surface by the third sputtering is A method of manufacturing a semiconductor device, which comprises a tensile stress.