JPS62293728A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To increase a growth rate in the direct thermal nitriding of an Si substrate by conducting the direct thermal nitriding of the Si substrate after the thermal oxidation of the Si substrate, the nitriding treatment of a thermal oxide film and the etching removal of the thermal oxide film. CONSTITUTION:When an Si substrate 1 is thermally oxidized and an oxide film is formed and the oxide film is nitrified and treated in ammonia or nitrogen/hydrogen gas, a layer in which there is interstitial Si in high concentration is shaped near the surface of the Si substrate 1. The layer 3 is left even by removing (etching) a thermal oxide film 2 to be nitrified at a low temperature, and the rate of nitriding is increased when the direct thermal nitriding of the Si substrate is performed in pure ammonia or nitrogen/hydrogen gas. The direct thermal nitriding film 4 of the Si substrate acquired through such treatment is used as an insulating film or an anti-oxidizing film for selective oxidation. Accordingly, the rate of direct thermal nitriding of the Si substrate can be increased by simple treatment.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention Industrial Application Field The present invention is directed to the use of a rapidly grown Si (silicon) direct thermal nitride film for selective oxidation of gate insulating films of MISFETs or various semiconductor devices. The present invention relates to a method of manufacturing a semiconductor device used as an anti-oxidation film.

Prior Art In conventional direct thermal nitridation of Si substrates, the growth rate of the nitride film is slow, so the film thickness that can be obtained within a practical growth time is
There were only a few dozen people, and semiconductor devices using this technology were not mainstream.

Problems to be Solved by the Invention As described above, in the prior art, there has been a problem that the growth rate of the nitride film is slow when directly thermally nitriding a Si substrate.

The present invention addresses this slow growth rate in direct thermal nitridation of Si substrates.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention provides direct thermal nitridation of the Si substrate following thermal oxidation of the Si substrate, nitridation treatment of the thermal oxide film, and etching removal thereof. It is something to do.

Operation The present invention improves the direct thermal nitridation rate of Si substrates by taking the above steps.

When Si is thermally oxidized and this thermal oxide film is further nitrided, interstitial S1 increases near the surface of the Si substrate. This interstitial Si remains even after the nitrided thermal oxide film formed on the surface is removed at low temperature. Furthermore, the direct thermal nitridation rate of the Si substrate is increased by the presence of this interstitial Si. Therefore, when the 31 surface is thermally oxidized, this thermal oxide film is nitrided, and the nitrided thermal oxide film is removed to expose the Si substrate surface, the Si substrate surface can be directly oxidized at a high nitriding rate. thermally nitrided.

EXAMPLE Hereinafter, an example of the present invention will be described with reference to the drawings.

After thermally oxidizing the Si substrate 1 to form an oxide film, when the oxide film is nitrided in ammonia or nitrogen/hydrogen gas, a layer containing a high concentration of interstitial Si is formed near the surface of the Si substrate 10. can. This layer 3 remains even if the thermal oxide film 2 to be nitrided is removed (etched) at a low temperature (
Figure 2). Direct thermal nitriding of the Si substrate in clean ammonia or nitrogen/hydrogen gas then increases the nitriding rate (Figure 3). Si obtained through such treatment
The direct thermal nitride film 4 on the substrate is used as an insulating film or an oxidation prevention film for selective oxidation.

FIG. 4 shows an example in which the Si thermal nitride film 4 grown in this manner is applied to a MISFET using a separation method using Si substrate selective oxidation (LC)005. is used as an oxidation prevention film for selective oxidation when forming LOGO3 isolation, and also as a gate insulating film of MISFET. Here, 5 in Figure 4 is L
Element isolation oxide film for OGO5 isolation, 6 in the same figure is Po1y-
5i gate electrode, FIG. 7 is an S/D impurity implantation region, FIG. 8 is an interlayer insulating film, and 9 is an aluminum wiring.

Effects of the Invention According to the present invention, it is possible to improve the direct thermal nitridation rate of a Si substrate by an extremely simple process, and it is a practical method for forming an insulating film and a substrate oxidation prevention film used in semiconductor devices. extremely useful.

[Brief explanation of drawings]

1 to 3 are cross-sectional views for explaining the treatment process in one embodiment of the present invention, and FIG. 4 is a cross-sectional view of a MISFET manufactured using the method of this embodiment. 1... Si substrate, 2... Nitrided thermal oxide film, 3... Interstitial Si high concentration layer, 4
...Si, thermal nitride film grown at an accelerated rate. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2 Figure 3

Claims (1)

[Claims] A method for manufacturing a semiconductor device, in which the surface of a silicon substrate is thermally oxidized to form an oxide film, the oxide film is nitrided, the nitrided oxide film is etched away, and the silicon substrate is directly thermally nitrided. .