JPS60145376A - Growing method of tungsten silicide film - Google Patents

Abstract

PURPOSE:To flatten the surface of a film at one stage by covering a silicon substrate with an insulating film formed with an aperture, embedding the aperture with a W layer under specific conditions and forming further W-Si on the insulating film and the W layer under specific conditions. CONSTITUTION:An insulating film (PSG, etc.) 2 is formed on the surface of a silicon substrate 1 and an aperture 4 is formed to the point where contact is taken. Gaseous WF6 and N2 are then supplied as gaseous raw material and the temp. of a reactor is maintained at 300-350 deg.C to grow a W layer 6 on the surface of the substrate 1 in the aperture 4 in chemical vapor phase under the reduced pressure. The W layer 6 having good adhesion is thus obtd. with decrease penetration 5. WF4 and SiH4 are then supplied and W-Si is uniformly grown on the film 2 and on the W layer 6 in the aperture 4 at 350-450 deg.C under the reduced pressure with good adhesion. The step (h) in the aperture 4 is thereby considerably decreased to about 0-3,000Angstrom .

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a method for forming a tungsten silicide film on an insulating film formed on a silicon substrate and in a window portion of the insulating film.

Prior art As shown in FIG.
When forming the tungsten silicide film 3, a step is formed on the surface of the tungsten silicide film 3 due to the step structure between the insulating film 2 and the silicon substrate 1. In order to use the tungsten silicide film as a wiring, it is desirable that this step be as small as possible and flattened. Wiring with steps may cause problems such as breakage at the steps.

OBJECTS OF THE INVENTION The object of the present invention is to continuously grow a tungsten film and a tungsten silicide film so that hole filling and wiring can be performed in a single process, thereby achieving planarization.

Structure and operation of the invention Hereinafter, the present invention will be described in detail along with examples.

In FIG. 2A, an insulating film (for example, PSG, etc.) 2 is formed on the surface of a silicon substrate 1, an opening 4 is formed at a contact point, and ringsten (W) is formed by low pressure CVD.
Layer 6 is formed and then tungsten silicide layer 7 is formed successively as shown in Figure B.

Low-pressure CVD is suitable for mass production by supplying raw material gas 8 to a diffusion furnace type reactor 9 shown in FIG. 5 and depositing pw or W-Si on silicon substrate 1 through a thermal decomposition reaction. Further, a parallel plate type reactor as shown in FIG. 4 can also be used. The silicon substrate 1 is placed on the base 11 and the source gas 8
A film is formed on the silicon substrate 1 by supplying -trA decomposition. In the present invention, the selective growth of W and the growth of W-St are performed multiple times in succession by switching the source gas and controlling the temperature of the reactor. This continuous process is detailed below: (1) Selective growth of W on the surface of the silicon substrate 10 in the opening 4 WF and nitrogen gas N2 are supplied as source gases, and the temperature of the reactor is set at 600 to 550°C. Grow W under reduced pressure. Although N2 can be added in addition to N2, the selectivity of W growth decreases when N2 is added. WF during the growth of W
Because 6 reacts with the underlying silicon, the silicon surface is eaten away to some extent.

The reaction occurs as follows: WF6 +St→W+SiF4, and W is deposited on the silicon surface. The formed W layer has a thickness of several hundred to several thousand λ
Can be formed to a certain extent. If the temperature of the reactor is raised to 350°C or higher, the aforementioned silicon surface will be etched into a large amount υ, making it unsuitable as a contact for the element, and
Below °C, problems arise in terms of adhesion. 300°C~
At 350° C., a W film with good adhesion and little biting into the underlying silicon is selectively formed, and the opening 4 is filled.

(It) Switch the WSt growth source gas to WF6 and S-H4, and heat at 350°C to 4.
W-8t was applied to the insulating film 2 and the W inside the opening under reduced pressure at 50°C.
Grows uniformly upwards. It is also possible to mix N2 into the raw material gas, and by mixing N2, W-Si containing a large amount of W is formed.

The reason why the temperature is set to 350° C. to 450° C. is that W-8i having good adhesion to the insulating film 2 is formed within this range.

Next, to explain the pressure inside the reactor in low pressure CVD, in the present invention, growth is performed under a reduced pressure of 1 torr or less, and the practical range is 0.1 to 1 torr, particularly 0.1 to 1 torr. At 0.4 torr, the grown layer does not become cloudy (large particles that occur when the reaction is intense or those grown in the gas phase adhere), and the formed film does not contain hydrogen or fluorine, resulting in a film with good adhesion. (H'p
If F is included, the film will peel off easily).

Next, to give an example of specific values for the raw material gas supply when the reactor is a parallel plate, in (1) selective growth of W, WF
6 is 1-10 ”7'g4.rLHN2 is 200 ”1
gain position.

N2 is 100C ring 14th, and in (11) W St growth, WF6 is 1 to 10"/n5iBr 5tH4
Is it 10~”00”/1rot? Do it with L.

As can be seen from the effects of the invention, according to the present invention, good contacts can be continuously formed using one CVD device, and flattened W −
For example, in the case of an insulating layer with a thickness of 1μ, which can be used for Si wiring, a step of nearly 1μ was created in the conventional method, but according to the present invention, the step is 0~3000! can be significantly reduced.

[Brief explanation of drawings]

Figure 1 is an explanatory diagram showing the film formation of conventional W-S.
FIGS. A and B are process diagrams for explaining the growth method of the present invention, FIG. 3 is an explanatory diagram of a low pressure CVD apparatus used in the present invention, and FIG. 4 is an explanatory diagram of another low pressure CVD apparatus used in the present invention. In FIGS. 2 to 4, main symbols 1... silicon substrate, 2... insulating film, 4... opening (placement), 5... biting, 6... tungsten layer,
7... Tungsten silicide layer, 8... Raw material gas, 9... Diffusion furnace type reactor Patent applicant Fujitsu Ltd. Representative Patent Attorney Gobe Tamamushi (one other person) Figure 1 Figure 2 Figure 3 Figure 4

Claims (1)

Claims: hfcD for forming a tungsten silicide film on the surface of an insulating film that covers a silicon substrate and has an opening partially formed therein, and on the surface of the silicon substrate within the opening. Tungsten is grown by chemical vapor deposition on the silicon substrate surface of the opening under reduced pressure at 300 to 350°C using WF as a source gas, and then tungsten silicide is grown at 650 to 4506C using WF6 and S t H4 as source gas. A method for growing a tungsten silicide film, which is characterized by continuous chemical vapor deposition under reduced pressure on an insulating film and tungsten in an opening.