JPH04286112A - Manufacture of sputtering-related semiconductor device - Google Patents

Abstract

PURPOSE:To prevent a sputtering film deposited on a shield laid out in such a fashion to surround a processing space of a sputtering device from being separated and dispersed due to internal stress and enhance manufacturing yield of IC or the like. CONSTITUTION:When sputtering is carried out for a wafer which forms an IC and a deposited to a shield involves internal stress, sputtering processing is placed between for a dummy wafer under the condition that an internal stress-involved film be formed. Two types of internal stresses of the film are canceled so that no deposited film may be separated, which inhibits the generation of dust and dirt.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to sputtering processing used in the manufacture of semiconductor devices, and particularly to suppressing peeling of a film adhering to a shield provided surrounding a sputtering space.

The principles and practices of sputtering processes used in the manufacture of semiconductor devices are well known to those skilled in the art. During sputtering processing, if sputtering material scattered from the target adheres to the inner wall of the processing equipment,
Since it becomes difficult to remove it, it is a standard specification for equipment configurations to provide a separation wall called a shield to prevent it from adhering to the inner walls.

0003

2. Description of the Related Art FIG. 3 is a diagram schematically showing a cross-sectional structure of a plasma sputtering apparatus provided with a shield. Reference will be made to this drawing below.

Reference numeral 1 denotes a chamber with an airtight structure, and when the plasma generated in the plasma generation space 2 collides with the target 3, the constituent substances of the target are thrown out in the form of fine droplets, and the sample 4 ( usually deposited on a semiconductor wafer).

[0005] At this time, since the droplets are scattered in all directions toward the target surface, a considerable amount of the droplets will also fly onto the inner wall surface of the chamber. If it were to adhere to the inner wall surface as it was, maintenance work on the apparatus would be difficult, so as shown in the figure, a shield 5 is provided to prevent sputtering deposition from occurring on the inner wall surface of the chamber. Since the shield can be removed, deposits can be removed relatively easily. Note that 6 is a clamper for fixing the wafer, and here the shield has a structure that also serves as a wafer support stand.

[0006]

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

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

[0008] This graph shows the plasma raw material gas N2.
It expresses the stress and composition of the produced film with respect to the supply rate, with tensile stress being positive and compressive stress being negative. The gas pressure is 4 mTorr when the N2 supply rate is 120 sccm or less.
, above that, it increases in proportion to the supply speed, 200sc
cm is 6 mTorr, and 300 sccm is 8 mTorr.

[0009] If a TiN film is to be used as a barrier film for a metal wiring film, it is desirable that its resistivity be as low as possible, and for this purpose it is required that the composition be close to the stoichiometric ratio. Therefore, according to the data in FIG. 2, the N2 supply rate is set at 150 sccm to 200 sccm. However, under this condition, 1010dyne
A compressive stress exceeding /cm2 is included in the deposited layer.

[0010] Although it is not preferable that the films deposited on the wafer contain either compressive or tensile stress, the films may be subdivided by patterning or
As a result of being subjected to treatments such as being laminated with films containing different types of stress, the internal stress is often alleviated to the extent that it does not become a problem overall.

However, on the processing device side, the situation is different. In a normal sputtering apparatus, wafers are processed one by one, so sputtering is performed 20 to 40 times just to process one lot of wafers, resulting in a thick sputtered film deposited on the shield. As the film thickness increases, the stress of the film also increases, and when the adhesion force to the shield is exceeded, the adhered film may peel off and fragments thereof may be scattered into the processing space. The peeled off pieces generated in this way are dust, which adhere to the wafer surface and impede good formation of elements.

[0012] An object of the present invention is to provide a sputtering treatment method that suppresses the generation of this kind of peeled pieces.
It is an object of the present invention to provide a method for manufacturing a semiconductor device with improved manufacturing yield.

[0013]

[Means for Solving the Problems] In order to achieve the above object, the semiconductor device method of the present invention uses a sputtering apparatus in which a shield is provided surrounding a space in which sputtering processing is performed. In manufacturing a semiconductor device, following the first sputtering, which is performed under conditions such that a deposited layer with desired film quality is deposited on the sample surface,
The second sputtering is performed under the condition that a film containing stress whose acting direction is opposite to the stress contained in the film attached to the shield surface by the sputtering is attached to the shield surface, and then the first sputtering or The method includes a step of performing sputtering to form a deposited layer containing the same type of stress as the deposited layer formed by the sputtering.

[0014] Also, in a typical embodiment of the present invention,
The film attached to the shield surface by the first sputtering includes compressive stress, and the film attached to the shield surface by the second sputtering includes tensile stress.

FIG. 1 is a flowchart showing the above-mentioned process, which is a feature of the present invention. After sputtering has been performed on a predetermined number of wafers, sputtering on regular wafers is interrupted, and strain relaxation sputtering using a dummy wafer is performed. I do. The layer deposited by this strain-relaxing sputtering contains stress whose acting direction is opposite to the stress contained in the layer deposited by the original sputtering process, and cancels out the internal stress of the film deposited on the shield surface. After that, sputtering is started again on the regular wafer.

[0016]

[Operation] Sputtering performed for the purpose of forming a deposited layer on a wafer forms a deposited film containing, for example, compressive stress on the shield surface, but according to the present invention,
Subsequently, a layer with tensile stress is deposited, so
The internal stress of the film attached to the shield cancels out and becomes weak.

[0017] If the internal stress is reduced, peeling due to it becomes less likely to occur, and the generation of dust that inhibits element formation is also eliminated. It is also clear from the graph of FIG. 2 that when sputtering is performed using the same apparatus, the stress contained in the deposited layer can be made to be of different types by selecting the processing conditions.

[0018]

[Example] It is common practice to form a structure schematically shown in FIG. 4 in an element 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 SiO2, 12 is a Ti film with a thickness of 100 to 500 Å, and 13 is 1
000-2000 Å TiN film, 14 is 3000-10
000 Å thick Al layer.

The sputtering apparatus used is shown in FIG. 3, and it supplies a gas containing 40 to 60% N2 in Ar at a pressure of 1.0 to 4.0 mTorr, turns it into plasma, and sputters the Ti target. to perform sputtering. Once a TiN film of a predetermined thickness has been deposited on a Si wafer on which an integrated circuit will be formed, the wafer is replaced and the same process is performed. Through this sputtering, a TiN film containing compressive stress is attached to the shield.

After sputtering several to one lot of Si wafers, dummy wafers are set and N2 1
Sputtering is performed by changing the processing conditions to 00% and 10 mTorr pressure. The processing time is several times to ten times that of depositing a TiN film on a regular wafer, and T
An iN film is formed on the shield to a sufficient thickness.

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

Sputtering deposited layers often contain compressive or tensile stress, and it is common for the direction of action to be reversed by changing the processing conditions. The present invention can also be applied to sputtering formation to prevent the attached film from peeling off.

[0023]

[Effects of the Invention] As explained above, in the present invention, compression (
After the formation of a film containing tensile (or tensile) stress has progressed to a certain extent, a film containing tensile (or compressive) stress is formed on the shield to relieve the internal stress of the film attached to the shield surface, so that the attached film does not peel off and scatter. This significantly reduces the amount of dust falling onto the wafer. Therefore, the occurrence of defective elements in the integrated circuit is suppressed, and the manufacturing yield of integrated circuit devices is improved.

[Brief explanation of the drawing]

[Figure 1] Process diagram showing the processing order of the present invention

[Figure 2]
Diagram showing the relationship between processing conditions and stress in the produced film

[Figure 3]
Schematic diagram showing the structure of sputtering equipment

[Figure 4] Diagram showing the 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 (SiO2) 12 Ti film 13 TiN film 14 Al layer

Claims (2)

[Claims] 1. Conditions for forming a deposited layer with a desired film quality on a sample surface in the manufacture of a semiconductor device using a sputtering apparatus in which a shield is provided surrounding a space in which sputtering processing is performed. Following the first sputtering treatment carried out in , a second sputtering treatment is performed under the condition that a film containing stress whose acting direction is opposite to the stress contained in the film adhered to the shield surface by the sputtering is attached to the shield surface. A method for manufacturing a semiconductor device, comprising the steps of performing sputtering, and then performing sputtering to form a deposited layer containing the same type of stress as the first sputtering or the deposited layer resulting from the sputtering. 2. The method of manufacturing a semiconductor device according to claim 1, wherein the film adhered to the shield surface by the first sputtering includes compressive stress, and the film adhered to the shield surface by the second sputtering includes compressive stress. A method for manufacturing a semiconductor device, characterized in that it contains tensile stress.