JPS5992995A - Method for forming silicide film of high-melting metal - Google Patents

Abstract

PURPOSE:To form a silicide film of high quality, by introducing an etching gas together with a plasma generating gas into a reaction chamber in manufacturing a silicide film of a high-melting metal by the sputtering of the plasma electric discharge method. CONSTITUTION:Substrates 7 mounted on a pallet 6 are placed in a high-vacuum vessel 4, and a high voltage is applied to a cathode part (numeral 9 indicates a shielding plate) consisting of a target 2, e.g. molybdenum silicide plate, a supporting plate 3 and permanent magnets 1. On the other hand, a plasma generating gas, e.g. argon, is introduced from a gas supply port 8 to generate a plasma in a region (b). The silicide of the target 2 formed by the resultant plasma is then applied to the substrate 7 (numeral 5 indicates a gas discharge duct port and numeral 10 indicates a shutter). In the above-mentioned method, the plasma generating gas and an etching gas, e.g. a halogenated hydrocarbon, in an amount of about 0.1-10% based on the plasma generating gas together are introduced from a supply port 11 into the vessel 4.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a technology for forming a high melting point metal silicide film.

(Structure of a conventional example and its problems) FIG. 1 is a vertical sectional view schematically showing the structure of a sputtering apparatus for explaining a conventional method of forming a high melting point metal silicide film. 1 is a magnet, which is provided to generate a magnetic field parallel to the target 2; 3 is a target support plate having a water cooling mechanism; these magnets 1, the target 2,
The target support plate 3 constitutes a cathode section.

This cathode portion is fixed in a vacuum container 4, and the vacuum container 4 can be maintained at a high vacuum by an exhaust port 5 of a vacuum system.

On the other hand, a pallet 6 is installed facing the surface of the target 20, and a wafer 7 is fixed to the pallet 6. The distance between the target 20 surface and the well huff is several tens of meters.

First, after setting the wafer 7 in the node 6, the inside of the vacuum container 4 is evacuated to a high degree of vacuum on the order of 10-7 Torr, and then argon gas is supplied from the gas supply port 8 to increase the inside of the vacuum container 4 to 10". Maintaining a vacuum on the order of Torr, and with the vacuum container 4 grounded, apply a voltage of -50 to the cathode.
When a negative voltage of approximately 0 volts is applied, a discharge occurs within the vacuum container 4. Here, in the area where the magnetic field near the target surface and the electric field caused by the applied voltage are perpendicular to each other, a high-density plasma is generated due to the magnetism and tron motion of the electrons ionized by the discharge, which nips the target and destroys the target molecules. It is attached to the surface of Waeno 7. In the high plasma region where the magnetic field and electric field are perpendicular to each other, collisions of gas molecules generate secondary electrons, which are accelerated along the electric field and collide with Waeno 7. The temperature of the way... rises, causing damage to the functional elements embedded in the way. It is connected to the same ground potential as the outer container 4.In order to prevent contaminants on the surface of the target 2 from adhering to the surface of the wafer 7 at the same time in the initial stage of sputtering, the sputterer 10 is After soaking in preliminary snow for 8 nights in a sheltered trench, high-purity target material was exposed to water...7
coated on top.

By the way, one of the problems when using this interstitial method to remove high melting point metal silicide as a ditarget material is that the purity of the film deposited on the wafer is low, making it difficult to manufacture semiconductor devices. It cannot be applied to

The cause of this is that heavy metal impurities, alkali metal impurities, etc. contained in the high-melting point metal silicide target itself are sludged, and a portion of the shield plate and shutter are slightly sludged.

(Object of the Invention) The present invention was made to solve the above-mentioned problems, and an object of the present invention is to provide an improved formation method for obtaining a high-melting point solicide film with high purity and high density. That is.

(Structure of the Invention) In the method of the present invention, when attaching target molecules to a wafer by sputtering using argon gas plasma discharge, an etching gas such as p-type gas is introduced into a vacuum chamber using fnI etching gas. The target molecules in the plasma region are thereby exposed to the etching atmosphere and react with the heavy metals being sputtered at the same time. The heavy metals that have reacted with the etching gas are vaporized and discharged out of the vacuum container by the vacuum system. At this time, the silicide target molecules will still react with the etching gas, but by appropriately controlling the ratio of the etching gas flow rate to the argon gas flow rate, the reaction can be...
It is possible to form a silicide film on a wafer without significantly reducing the formation rate of the sputtered film deposited thereon. As a result, the high melting point metal silicide film deposited on the wafer can be a highly pure film.

(Description of Embodiments) FIG. 2 is a cross-sectional view schematically showing the structure of a sputtering apparatus for explaining the present invention in detail. Except for the points shown in FIG. 1, the other parts 1 to 10 are the same as shown in FIG.

The magnetic field generated by the magnet 1 is generated in a direction parallel to the surface of the target 2, as shown by the dotted line a, and its average value can be expressed as B. Unfortunately, the electric field E generated by the voltage applied between the cathode section and the vacuum vessel 4 is generated in a direction perpendicular to the magnetic field.

Therefore, the argon gas plasma has a maximum density in the entire region, and the electrons ionized by this discharge perform a magnetic movement at a speed of v=E/100, which strikes the target. The argon gas flow rate at this time is usually about 80 to 11005 CC.

Here, the present invention is characterized in that, for example, a halogen-based etching gas is supplied through the inlet 11. The etching gas flow rate is allowed in a range of 0.1% to 10% of the argon gas flow rate. This etching gas reacts with the sputtered molecules primarily in the region, and the reaction products are evacuated through a vacuum system and the remaining sputtered molecules are deposited on the wafer. The balance between the amount of etching and the amount of sputtering changes depending on the applied power, the pressure inside the vacuum chamber, etc., and it becomes necessary to change the ratio of the etching gas flow rate. For example, power 71<w.

At a pressure of 8 mTorr, an argon gas flow rate of 100 SC
For CM, the most favorable results were obtained when the etching gas flow rate was 0.2% to 0.3%j.

An example of chemical analysis of impurities in a film formed by sputtering from molybdenum silicide tercerate shows that in the conventional method, alkali metals are 5 ppm to 8 ppm, heavy metals such as iron and nickel are 100 ppb to 1 ppm.
However, when the film was formed by the method of the present invention, the alkali content was 100 ppb and the heavy metal content was 10 ppb or less.

(Effects of the Invention) As explained above, according to the method of the present invention, impurities in a high melting point metal silicide film can be reduced and stable film formation can be achieved. Furthermore, when a high melting point metal silicide film is formed by the method of the present invention, the stress remaining in the film is significantly reduced compared to conventional methods, and the growth rate of the silicide particles can be controlled very easily. I also understood.

When the method according to the present invention is applied to the manufacture of semiconductor devices, it exhibits a remarkable effect on stabilizing the electrical characteristics thereof.

[Brief explanation of drawings]

FIG. 1 is a vertical cross-sectional view schematically showing the configuration of a sputtering apparatus for explaining a conventional method for forming a high-melting-point metal silicide film, and FIG. 2 is a schematic diagram of the configuration of a sputtering apparatus for explaining the present invention in detail. FIG. 1......Magnet, 2...Target, 3...Target support plate,
4... Vacuum container, 5... Vacuum system exhaust port, 6... Four pallets, 7...
... Wafer, 8 ...--Mountain/Gas supply port, 9
・・・・・・・・・ Shield plate for capturing secondary electrons,
1o...river...shutter, 11.m mountain/etching gas supply port. Patent applicant Matsushita Electronics Co., Ltd.

Claims (3)

[Claims] (1) A method for forming a high melting point metal silicide film, which comprises introducing a gas having an etching property to at least the silicide into a reaction chamber during deposition and formation of the high melting point metal silicide film. (2) A method for forming a high melting point metal silicide film according to claim (1), characterized in that a gas having etching properties is introduced intermittently. (3) The high melting point metal silicide according to claim (1), wherein the concentration of the gas having etching properties introduced is 0.1% to 10.0% with respect to the total gas flow rate. Film formation, method.