JPH0499270A - Sputtering target and film formation by sputtering - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Summary] Regarding the sputtering method for forming a film on a substrate, high-speed film formation is possible in order to make the film formed into a high quality film, and the film formation is stable. With the aim of making it possible to perform sputtering, a sputter target is used, which has a protective film made of a material that is more corrosion resistant and harder than the material to be sputtered, on the cooling surface of the target body made of the material to be sputtered. The sputter target is cooled by bringing cooling water into direct contact with the protective film, and the sputter target has a metal material between the target body and the protective film that is softer than the metal of the protective film. In addition, the structure is such that an adhesive layer made of a material having a higher melting point than the material to be sputtered may be present.

[Industrial application field]

The present invention relates to a sputtering method for forming a film on a substrate, and particularly to a sputter target and a sputtering film forming method.

Sputtering is a technology that deposits sputter target material on the surface of a substrate, and is mainly used for semiconductor devices,
It is used for forming non-magnetic or magnetic metal films and insulating films in the manufacturing of magnetic devices and optical devices.

For example, in the manufacture of semiconductor devices, aluminum or aluminum alloy (e.g.
Pure AI, Al1%Si, Al-1%5i-0,5%
Films of Cu, etc.) are formed by sputtering, and it is desired to improve the film quality.

[Conventional technology]

It is well known that the quality of an aluminum film formed by sputtering is sensitively affected by sputtering conditions. In order to obtain a high quality film as a wiring layer,
It is necessary to suppress the contamination of impurities during film formation, and for this purpose,
It is required to reduce residual gas in the vacuum atmosphere during sputtering and to perform film formation at high speed.

Speeding up film formation can be achieved by increasing the power input to the sputter target (hereinafter referred to as target), but as the power increases, the aluminum of the target material (sputtered material) begins to melt and stable sputtering is maintained. become unable. Therefore, it is necessary to cool the target as much as possible, and various cooling methods have been considered for high-speed film formation.

FIG. 3 is a schematic sectional view of a target portion for explaining the conventional example, and this conventional example is the most popular method.

In the figure, a support plate 13 made of a metal with high thermal conductivity (for example, copper or a copper alloy), on which a target 11 is attached, is used, and cooling water I
2 for cooling. The surface of the support plate 13 faces the vacuum atmosphere, and the target 11 is attached using a low melting point (approximately 2
This is done through the solder material 14 at a temperature of about 0.0°C.

In this case, if a large amount of power is applied, the solder material 14 will begin to melt and the target 11 will easily peel off, and the solder material 14 will contaminate the vacuum atmosphere and deteriorate the quality of the aluminum film being formed. .

As a method that does not use the solder material 14, a support frame (in which the peripheral edge of the target 11 is fitted and inserted instead of the support plate 13) is used.
The inside of the target 11 is water-cooled), and the peripheral side of the target 11 is brought into close contact with the support frame due to target MlO thermal expansion.
There is something that supports 1. In this case, target l
The dimensional accuracy between the I and the support frame is extremely important, and it is quite difficult to achieve stable cooling.

FIG. 4 is a schematic sectional view of a target portion for explaining another conventional example, and this conventional example is a method in which the target can be reliably cooled without using solder material.

In the figure, a target 21 is airtightly fixed to a support frame 23 via a gasket 24 (for example, an O-ring) at the peripheral edge of the back surface to maintain a vacuum atmosphere, and is cooled by direct contact with cooling water 22 from the back surface. Since no solder material is used as in the conventional example, a large amount of electric power can be input. This method is generally called a direct cooling type because the target 21 is directly cooled by the cooling water 22.

[Problem to be solved by the invention]

However, in the above-mentioned conventional example of the direct cooling type, the target 21
Since the back surface is also made of aluminum or aluminum alloy, which is the material to be sputtered, ■ Corrosion is likely to occur in the parts that are in direct contact with the cooling water 22, and the corrosion becomes moss-like, so that the target 21 may be damaged during long-term use. Cooling efficiency decreases, ■ Target 21
The target 21 is easily damaged during handling such as removal, and if the scratches are on the periphery of the back surface, the target 21
■ When the corroded target 21 is removed and used again, the target 2 may be damaged due to misalignment of the installation.
However, it is difficult to form a high-quality aluminum film as a wiring layer in a stable manner.

Therefore, the present invention aims to provide a sputtering method for forming a film on a substrate, which enables high-speed film formation and stable film formation in order to obtain a high quality film. With the goal.

[Means to solve the problem]

FIG. 1 is a diagram explaining the principle of the present invention.

In order to achieve the above object, the sputtering method according to the present invention is a direct cooling type sputtering method using the target 1 of the present invention.

That is, the target 1 is characterized by having a protective film 1b made of a material with higher corrosion resistance (and harder) than the material to be sputtered, on the cooling surface of the target main body 1a made of the material to be sputtered. Target body 1
An adhesion layer 1c made of a material that is softer than the metal of the protective film ib and has a higher melting point than the material to be sputtered may be interposed between the protective film a and the protective film 1b.

In addition, in the film forming method, using the target l,
The target 1 is cooled by bringing the cooling water 2 into direct contact with the protective film 1a.

[For production]

The sputtering method according to the present invention is a direct cooling type in which the target 1 is cooled by bringing the cooling water 2 into direct contact with the protective film 1b provided on the target 1. The protective film 1b is chemically stable and insoluble in the cooling water 2 due to its corrosion resistance, and is also harder than the material to be sputtered.

From this, it is possible to increase the power input to target 1 and achieve high-speed film formation, and the above-mentioned problems ① to ③ are resolved, and high-quality films can be stably formed. can do.

The interposition of the adhesive layer 1c is a measure against the possibility that the protective film 1b easily peels off from the target body 1a (sputtered material) due to poor conformability at the bonding surface, and the softness of the adhesive layer 1c prevents the protective film 1b from peeling off. To prevent. The adhesive layer 1c does not melt unlike conventional solder materials due to its melting point.

〔Example〕

Embodiments of the present invention will be described below with reference to the cross-sectional view of the target portion shown in FIG.

This embodiment takes as an example the case where the material to be sputtered is aluminum or an aluminum alloy, in accordance with the conventional example.

In the figure, 1 is a target, 2 is cooling water, 3 is a support frame, and 4 is a packing (O-ring).

The target 1 has an outer diameter of 280 mmφ including the support part,
The target body 1a is made of aluminum or an aluminum alloy, and a region of 250 mmφ in the center of the upper surface (front surface) in the figure is the sputtering surface, and a 1.
Adhesion layer 1c made of copper of ~100 μm and thickness 10~
A protective film 1b made of titanium nitride with a thickness of about 100 μm is sequentially deposited. The copper film used as the adhesive layer IC is ion- and
The titanium nitride film serving as the protective film 1b can be formed by reactive ion blating. Further, the adhesive layer 1c can be formed by a wet plating method or a sputtering method, and the protective film 1b can be formed by a reactive thermal spraying method or a sputtering method. Due to the interposition of the adhesive layer 1c, the protective film 1b does not peel off from the target body 1a during temperature fluctuations of the target 1 or during handling.

The support frame 3 is shaped like a box and has a flange 3a on its opening side, and an electromagnet 5 is disposed inside, so that the target 1 faces the protective film 1b toward the box to airtightly cover the box. It is fixed to the flange 3a via the packing 4. Further, the flange 3a is hermetically fixed to a vacuum chamber (not shown), so that the sputtering surface of the target I faces the vacuum atmosphere.

The electromagnet 5 is used to confine plasma near the sputtering surface of the target 1 by its magnetic field, thereby increasing sputtering efficiency.

A cooling water outlet 6a and a cooling water outlet 6b are provided on the bottom of the box between the protective film 1b, the inner surface of the box, and the electromagnet 5.
The cooling water 2 flowing through the cooling water flow path 6 cools the target J by directly contacting the protective film 1b. The gap between the protective film 1b and the electromagnet 5 is about 10 mm.

By doing this, the target 1 will not be corroded by the cooling water 2, and the maximum power that can be input to the target 1 can be maintained at 18 to 20 KW for a long period of time, and the film forming rate Compared to the conventional example shown in the figure, an increase of about 50 to 60% could always be secured. However, the installation of Target 1 prevents scratches on the back side of the target during handling such as removal.
Target 1 can now be reliably fixed airtight even when used repeatedly.

Incidentally, in the conventional film forming method described in FIG. 4, the above film forming speed could be obtained in the initial stage, but as the period of use of the target 21 becomes longer, the target 21 becomes overheated and it becomes difficult to maintain stable sputtering. was becoming difficult.

According to an example of the embodiment, a target 1 whose target body 1a is made of an aluminum/I% silicon alloy is used, the sputtering pressure is 1 to 100 mTorr, the argon flow rate is 10 to 150 sec, the input power is about 18 KW, and the substrate temperature is By heating the temperature to 350 to 450°C, an aluminum-silicon alloy film can be formed to a thickness of 1 μm in about 30 seconds, and the throughput is improved by about 30% compared to the conventional example shown in Figure 3. .

However, in this high-speed film formation, even if the substrate temperature is low as mentioned above, the aluminum being formed has excellent fluidity, and even if there are steps on the substrate surface, the film forming surface is flat, making it possible to form fine wiring. Very favorable results are obtained for the formation. The wiring obtained by patterning the aluminum-silicon alloy film formed to a thickness of 1 μm has a lifespan of about 1 μm with respect to current density, compared to the conventional example shown in FIG.
It was also confirmed that there was an order of magnitude improvement.

The above-mentioned embodiment has been explained by taking as an example the case of forming an aluminum film as a wiring layer of a semiconductor device, but in the sputtering method of the present invention, aluminum, titanium, zirconium, tungsten can be used as the sputtered material of the target body la. , molybdenum, gold, tantalum, niobium, palladium, silver, zinc, ruthenium, tellurium, alloys based on these metals, magnetic metals such as chromium, nickel, permalloy, titanium, tanksten, molybdenum silicides, It is possible to form films of various materials stably and at high speed using silicon, the above-mentioned oxides (quartz, alumina, etc.), or mixtures thereof, thereby reducing contamination of impurities during film formation. This allows the film to be of high quality.

The material of the protective film 1b at that time is titanium, zirconium,
hafnium, molybdenum, chromium, tungsten nitride, carbide, or boride, titanium, aluminum,
Vanadium alloy or a combination thereof is selected as appropriate, and the material of the adhesive layer IC is copper, molybdenum,
It is preferable to appropriately select from chromium, an alloy containing one or more of the above-mentioned copper and chromium as a main component, or a combination thereof. If there is no risk of peeling off of the protective film 1b even without the interposition of the adhesive layer 1c, the adhesive layer 1c
may be omitted.

〔Effect of the invention〕

As explained above, according to the present invention, high-speed film formation can be performed stably with respect to the sputtering method for forming a film on a substrate, and it is possible to stably form a high-quality film. For example, it can be applied to wiring layers of semiconductor devices to improve their quality.

[Brief explanation of drawings]

Fig. 1 is a diagram explaining the principle of the present invention, Fig. 2 is a cross-sectional view of a target part for explaining an embodiment, Fig. 3 is a schematic cross-sectional view of a target part for explaining a conventional example, and Fig. 4 is a cross-sectional view of a target part for explaining a conventional example. FIG. 2 is a schematic cross-sectional view of a target portion for explaining a conventional example. In the figure: 1. 11.21 is the target, la is the target body, 1b is the protective film, lc is the adhesive layer, 2, 12.22 is the cooling water, 3.23 is the support frame, 13 is the support plate, 4.24 is the packing, 14 is It is solder material. 1°Kuget Mouse Target Body S'f Magnet 6 (L ''/9i Ikegi Entrance 6 Akane Wa Trap Approximately 6b > Reio P Tree Exit Embodiment F Description : Protection Group 2: '/94 Squad 7a' Targeted wood body 1c' Fake, explanatory diagram of the principle of attaching to the layered wood No. 1 Figure 11゛Tarke Soto 12') Replaced p water I3. Support plate 14: Solder material Figure 21 Target 23, supporting shaft 22 Cooling water 24 Parahen et al.'s target cross-sectional view for explaining conventional PJE No. 4

Claims (1)

[Scope of Claims] 1) A protective film (1b) made of a material having higher corrosion resistance and harder than the material to be sputtered is provided on the cooling surface of the target body (1a) made of the material to be sputtered. Features sputter target. 2) The target body (1a) and the protective film (1b)
In between, an adhesive layer (made of a material that is softer than the metal of the protective film (1b) and has a higher melting point than the material to be sputtered) is formed.
Sputter target according to claim 1, characterized in that 1c) is present. 3) When performing sputtering to form a film on a substrate, the sputter target (1) according to claim 1 or 2.
A sputter film forming method, characterized in that the sputter target (1) is cooled by bringing cooling water (2) into direct contact with the protective film (1b).