JPH02205666A - Formation of sputtered film - Google Patents

Abstract

PURPOSE:To prevent cracking due to the internal stress of a sputtered film and to form a thick sputtered film on a substrate by applying reverse bias electric power to a substrate 2 and increasing the above bias electric power according to sputtering time. CONSTITUTION:A substrate 2 is disposed in a manner to be opposed to a target 1. The target 1 is sputtered toward the substrate 2 to form a sputtered film 3. Reverse bias electric power is applied to the substrate 2 from a high-frequency electric power source 4 via a substrate fixture 8. Further, the reverse bias electric power is increased by means of a power controller 41 with the growth of the sputtered film 3. By this method, a difference in the internal stress of the sputtered film 3 can be removed and, as a result, the thick sputtered film 3 can be formed without causing cracking.

Description

[Detailed Description of the Invention] [Summary] A method for forming a sputtered film on a substrate surface by sputtering, which eliminates the occurrence of cracks due to internal stress in the sputtered film.
The purpose of the present invention is to provide a method for forming a sputtered film that can form a thick sputtered film on a substrate, and a method for forming a sputtered film by sputtering the target on the surface of a substrate that is placed facing the target. The method is characterized in that reverse bias power is applied to the substrate from a power source and the bias power is increased with sputtering time.

[Industrial application field]

The present invention relates to a method for forming a sputtered film on a substrate surface by sputtering.

In various electronic devices, for example, substrates with a sputtered film of a high-melting point metal such as molybdenum, tungsten, or titanium-tungsten alloy formed on the surface are used, but if the sputtered film is formed too thick, cracks will occur due to internal stress, so the thickness is less than 3μ. A sputtered film is formed to a thickness of .

Under these circumstances, for substrates where electrical resistance is a problem, it is necessary to form a thick sputtered film to reduce the electrical resistance as much as possible. There is a need for a method of forming a thick sputtered film.

[Conventional technology]

Conventionally, in the method of forming a sputtered film, in order to control the tensile stress generated in the sputtered film that acts in the direction of peeling the sputtered film from the substrate, stress in the sputtered film is reduced by applying a constant reverse bias power to the substrate. A sputtered film forming method has been used in which the sputtered film is changed to a compressive side (stress acting in the opposite direction to the tensile stress) to prevent cracks from occurring due to the tensile stress of the sputtered film itself.

This is because when the sputtered film is peeled off from the substrate, the sputtered film curls toward the front surface in the opposite direction to the substrate, so there is a stress distribution inside the sputtered film as shown by C in Figure 2. Since there is a stress difference corresponding to T2-TI, this stress difference causes cranking even under compressive stress.

The present invention has been made to solve the above-mentioned drawbacks, and is designed to prevent the occurrence of cranks due to the internal stress of the sputtered film.
However, it is an object of the present invention to provide a method for forming a sputtered film that can form a thick sputtered film on a substrate.

[Problem to be solved by the invention]

However, when forming a sputtered film thicker than 3μ, a constant reverse bias power (power with a potential opposite to that of + ions, i.e., power with a potential on one side) that changes the pressure of the sputtered film to the compression side is required. ) to the substrate, it was not possible to prevent the occurrence of cranking, and it was difficult to form a thick sputtered film.

[Means for solving the problem] When the sputtered film is peeled off from the substrate, the sputtered film curls toward the surface side in the opposite direction to the substrate, so there is a stress distribution inside the sputtered film as shown by C in Figure 2. This is because there is a stress difference corresponding to T2-Tl between the front side and the back side, and this stress difference causes cracks to occur even under compressive stress.

In order to achieve the above object, in an apparatus for forming a sputtered film on the surface of a substrate 2 placed facing a target 1 as shown in FIG. 3, when applying reverse bias power to the substrate 2 from a power source 4, , the bias power is increased with sputtering time so as to reduce the internal stress difference in the sputtered film 3.

[Effect]

In the present invention, the output of the power source 4 is increased with respect to the sputtering time as shown in B in FIG. 1 according to a program set to reduce the internal stress difference between the front side and the back side of the sputtered film 3. By doing this, the sputtered film is formed so that the internal stress of the sputtered film becomes constant at each film thickness position, as shown in FIG. 2D.

Therefore, even if the sputtered film is formed to be thick, there is no stress difference between the front side and the back side, and it is possible to prevent cranking due to the stress difference.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 3 is a sectional view of a sputtering apparatus implementing the present invention. The target 1 is made of a high melting point metal such as molybdenum (MO), and is installed in a vacuum container 5 in an insulated state.

A substrate 2 on which a sputtered film 3 is formed is arranged to face a target 1, and a sputtering gas 6 such as argon (A r ) is introduced between the target 1 and the substrate 2 at a set pressure. ing.

A DC power supply 7 is connected to the target 1, and sputtering power is applied thereto. Then, the sputtering gas 6 ionized in the vacuum chamber 5 collides with the target 1, and the target 1 is blown against the substrate 2 to form a sputtered film 3.

At this time, the sputtered film 3 formed generally has tensile stress, but in order to change this tensile stress to a compressive side,
Reverse bias power is applied to the substrate 2 by a high frequency power source 4 via a substrate fixing jig 8 using a vacuum pump.

Further, the high frequency power source 4 is connected to a power controller 4 so as to increase the reverse bias power as the sputtered film 3 grows.
1.

Here, to explain the reverse bias power in a little more detail, when the output (bias power) of a high frequency power source is applied in a state where the vacuum container 5 is filled with a gas 6 such as argon (Ar), the filled gas Due to the discharging action of 6 itself, it becomes as if the applied bias power was rectified to the negative side. In the present application, this negative bias power is applied to the substrate as reverse bias power.

Furthermore, the control of the reverse bias power is carried out by programming the power controller 41 in advance to apply a reverse bias power such that the internal stress of the sputtered film 3 is constant with respect to the growth time of the sputtered film 3, that is, the sputtering time. It will be done. The amount of reverse bias power appropriate for the film thickness is programmed to increase continuously or stepwise with reference to values obtained from experimental data and the like.

FIG. 4 shows an example in more detail.

When forming a sputtered film 3 with a thickness of 3 μm using molybdenum as the target 1 and argon as the sputtering gas 6, the substrate 2 is inverted as shown in FIG. Apply bias power in increasing steps. As a result,
The sputtered film was formed without any cracks.

Although the present embodiment has been described using a high frequency power source, it goes without saying that a DC power source may also be used.

[Effects of the Invention] As is clear from the above description, according to the present invention, by eliminating the difference in internal stress of the sputtered film, it is possible to form a thick sputtered film without generating cracks, and the sputtered film can be formed thickly without cracking. By forming a thick film, electrical resistance can be reduced and performance can be improved.

[Brief explanation of the drawing]

Fig. 1 is a diagram explaining the principle of the present invention, Fig. 2 is a diagram showing the relationship between film thickness and stress, Fig. 3 is a sectional view of an apparatus for carrying out the invention, and Fig. 4 is an embodiment of the invention. It is a diagram. In the figure, is the target, is the substrate, is the sputtered film, and is the high-frequency power source.

Claims (1)

[Claims] In the method of sputtering the target (1) to form a sputtered film (3) on the surface of a substrate (2) disposed facing the target (1), the substrate (2) is connected to a power source (4). A method for forming a sputtered film, characterized by applying reverse bias power and increasing the bias power as the sputtering time increases.