JPS62133724A - Formation of thin film by bias sputtering - Google Patents

Abstract

PURPOSE:To obtain a thin film having a uniform thickness, by arranging a substrate formed of a semiconductor larger than a semiconductor sample between or around the semiconductor sample and an electrode holding the same and thus performing the sputtering process. CONSTITUTION:An auxiliary semiconductor substrate 12 larger in size than a semiconductor substrate 11 serving as the sample on which a film is to be deposited is provided between or around the semiconductor substrate 11 and an electrode 12 holding the substrate 11. The substrate 12 has a thickness larger than that of the substrate 11. The substrate 12 is provided with a recess at the center thereof. Accordingly, the boundary variation between glow and dark sections is decreased near the substrate 11 and therefore the sputtering effect is relatively uniformized over the surface of the substrate 11. Thus, a difference in thickness between the central and peripheral sections is decreased and a thin film having a uniform thickness can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a method for producing a bias-sputtered thin film in which a bias-sputtered thin film is deposited on the surface of a semiconductor sample using high-frequency discharge plasma.

[Technical background of the invention and its problems]

Recently, in the process technology of semiconductor integrated circuits, metal or 810! Bias sputtering techniques for forming thin films are being actively developed. Conventionally, a metal plate or one coated with a silicon thin film on the surface of the metal plate has been used as the flat plate electrode on which the semiconductor substrate as the sample on which the thin film is to be deposited is placed, but the problem is that spatial fluctuations at the boundary between the glow and the dark area have been avoided. Therefore, the thickness of the thin film deposited on the semiconductor substrate as a sample is extremely unrestricted, which poses a problem in the manufacture of integrated circuits.

[Purpose of the invention]

The present invention has been made in view of the above points, and reduces the spatial fluctuation of the boundary between the glow and dark areas on the surface of a semiconductor substrate as a sample on which a thin film is to be deposited, thereby obtaining a thin film of uniform thickness. An object of the present invention is to provide a method for manufacturing a bias sputtered thin film.

[Summary of the invention]

The present invention involves depositing a thin film using a bias batter device, as shown in FIG.
A substrate 42 made of a semiconductor and having a diameter larger than that of the sample 41 is placed between or around the sample 41, for example. In this case, the thickness of the substrate made of semiconductor is preferably equal to or greater than the thickness of the semiconductor sample on which the thin film is deposited, and the electrode 43 is hollowed out or provided with a recess 45 in the center.
The height from the contact surface to the surface is made equal between the semiconductor sample 41 and the substrate 42 made of a semiconductor.

〔Effect of the invention〕

When a conventional bias sputtering device is used, as shown in FIG.
4 and the dark area 35 change at the outer peripheral position of the sample 31. Therefore, the sputtering action at the outer periphery is more intense than at the center, resulting in a thinner film at the outer periphery. On the other hand, by installing the substrate 42 made of a semiconductor as in the present invention, the change in the boundary between the glow 45 and the dark area 46 is small in the vicinity of the semiconductor sample 41 as shown in FIG. The sputtering action within the plane of the film 41 becomes relatively uniform, and the difference in film thickness between the central portion and the outer peripheral portion is reduced.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of a bias sputtering apparatus used in the same embodiment, and FIG. 2 is an enlarged view of the main parts thereof.

In the figure, 11 is a semiconductor substrate as a sample on which a thin film is deposited, 12 is an auxiliary semiconductor substrate, 13 is a substrate support and electrode, 14 is a target material, 15 is a target electrode,
16.17 is a high frequency oscillator, 18 is an exhaust system, 19 is A
r is a gas supply device, 9.10 is a capacitor, and l is a vacuum container.

The feature here is that an auxiliary semiconductor substrate 12 larger than the semiconductor substrate 11 is placed between or around the semiconductor substrate 11 as a sample on which a thin film is to be deposited and the electrode 13 on which the semiconductor substrate 11 is placed. In this case, the thickness of the semiconductor substrate 12 can be adjusted by hollowing out the center or providing a recess 20 using a material that is greater than or equal to the thickness of the semiconductor substrate 11 as a sample, so that the thickness of the semiconductor substrate 12 can be adjusted from the contact surface with the electrode 13 to the surface as shown in FIG. It is important that the semiconductor substrate 11 and the semiconductor board 12 have the same height. The semiconductor substrate 11 may be an SO8 substrate, a three-dimensional IC substrate, or the like as a sample, and the semiconductor substrate 12 may be one in which a silicon layer is formed on the surface of an insulating substrate.

Actually, using the apparatus shown in Fig. 1, a 5R film with a thickness of 2 μm at the center was placed on a Si substrate with a diameter of 4 inches as a sample.
An experiment was conducted to deposit an OA film. The discharge conditions were Ar gas pressure IQm'l'orr and high frequency power 1.5 kW.

8i0. The target DC bias was 800V, and the substrate side DC bias was 130V. As shown in FIG. 2, the auxiliary Si substrate was placed on a 6-inch St substrate 12 with a 4-inch diameter hollowed out in the center so that the heights were the same. As a result, as shown in Fig. 5, in the conventional bias sputtering method, as shown in (a), 15 to 16%
In the method of the present invention, the variation in film thickness was reduced to about 11 to 12%, as shown in (b). Here, the variation was measured at 5 points within the surface of a 4-inch wafer, and the film thickness of each was set as TI (1=1 to 5), and the variation D was determined by the following formula.

[Other embodiments of the invention]

According to the above embodiment, the material of the target 14 is 8i0! was used, but similar effects can be obtained with metals such as titanium and tungsten. Further, the positional relationship of the two electrodes 13.15 for generating high-frequency discharge does not have to be parallel, they can be upside down, and the same effect can be obtained even if they are not horizontal.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of a bias sputtering apparatus used in an embodiment of the present invention, and FIG. 2 is a cross-sectional view showing an enlarged view of its main parts.
FIGS. 3 and 4 are explanatory diagrams showing the state of the boundary between a dark area and a glow according to the conventional method and the method of the present invention, and FIG. 5 is a characteristic diagram showing the difference in effect between the conventional method and the method of the present invention. DESCRIPTION OF SYMBOLS 11... Semiconductor substrate (sample), 12... Semiconductor substrate, 13... Substrate support stand and electrode, 14... Target material, 15... Target electrode, 16.17... High frequency oscillator, 18... Exhaust device, 19... Ar gas supply device, 8.9... Capacitor, 1... Vacuum container. Agent Patent Attorney Noriyuki Ken Yudo Takehana Kikuo Figure 1 Figure 2 Rinsaya's I〈Rakki D (Saki) (α) No. 1 Bakutsuki D (Bow) Figure 5

Claims (3)

[Claims] (1) When depositing a bias-sputtered thin film on the surface of a semiconductor sample using high-frequency discharge plasma, a substrate made of a semiconductor larger than the conductor sample is installed between or around the semiconductor sample and the electrode that holds it. A method for manufacturing a bias sputtered thin film. (2) Claim 1, characterized in that a recess or hole having a diameter and height substantially equal to that of the semiconductor sample is formed in the substrate made of semiconductor so that the semiconductor sample is accommodated within the substrate made of semiconductor. A method for producing bias sputtered thin films. (3) A method for producing a bias sputtered thin film according to claim 2, characterized in that the semiconductor sample is positioned at the center of a substrate made of a semiconductor.