Fishing – trapping – and vermin destroying
Patent
1991-10-18
1994-05-24
Chaudhuri, Olik
Fishing, trapping, and vermin destroying
437247, H01L 2102
Patent
active
053148479
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a method of processing a semiconductor substrate surface and a device therefor, and, in particular, to various methods of improving the quality of a semiconductor substrate surface, performed partway during the process of manufacturing an LSI or the like.
BACKGROUND ART
In addition to basic processes such as photolithography, etching, and film growth during the sequence of steps in the manufacture of an LSI, processing that improves the quality of the surface of the semiconductor substrate material is required. There are many different types of such processing, depending on purpose and method--typical examples are described below.
(1) Density Increase Process
An isolating substance such as a silicon oxide layer deposited on a semiconductor substrate by chemical vapor deposition (CVD) has insufficient film properties, not just because the linkages between atoms are insufficient but also because a water component is included. Therefore it is necessary to increase the densities of such films by high-temperature heating. This annealing step is usually done by using a tubular-shaped kiln to heat the substrate in a variety of gas environments, depending on the application.
(2) Interface Reaction Promotion Process
During the process of forming an LSI, a large number of structures where different materials are in direct contact with each other are used, and thermal processing is also used to promote interface reactions between such substances. For example, in order to make contact with a silicon substrate, aluminum or an aluminum alloy is placed in contact with the silicon semiconductor substrate. In order to ensure an electrical path between the two substances, it is known to perform heating to sinter the aluminum using the reducing characteristics of aluminium in a hot environment on a thin silicon oxide film formed on the silicon surface.
In addition, after a thin titanium layer is deposited on a silicon semiconductor substrate by sputtering, titanium silicide (TiSi.sub.2) is formed from the reaction between titanium and silicon by thermal processing at about approximately 600.degree. C., and the surface resistance of the silicon semiconductor substrate that is being processed can be reduced thereby. This reaction is usually achieved by heating the silicon semiconductor substrate that is being processed to over approximately 600.degree. C. in a kiln maintained in a nitrogen atmosphere or a vacuum, in order to prevent oxidation of the titanium.
(3) Activation Process
Thermal processing at a high temperature is performed in order to activate impurities inserted into a semiconductor substrate by a method such as ion implantation.
(4) Surface Oxidation Process
In processes such as photolithography, when a film of an organic substance such as resist is formed on a semiconductor substrate surface, a liquid consisting of the resist dissolved in a solvent is coated onto the surface and dried. In this case, particularly when the substrate surface is of aluminum or an aluminum alloy, the liquid of the photoresist coated onto the surface can easily be repelled thereby, and it often happens that the adhesion thereof is insufficient. Therefore, surface oxidation is performed by oxygen plasma processing, to convert the substrate surface into a hydrophilic surface.
(5) Ashing Process
To remove an organic substance such as a resist from a substrate surface, ashing is often used conventionally to oxidize the organic substance into carbon monoxide and carbon dioxide by a discharge plasma of a gas whose main component is oxygen.
(6) Crystallization
With a liquid-crystal substrate, a step that deposits an amorphous layer on a glass plate is used. From the characteristics point of view, single-crystal silicon would be ideal as a silicon layer on this substrate, but in practice this is not possible, so the formation of a polycrystalline silicon layer is preferred. However, since the substrate glass has a low heat resistance, it cannot be heated to the high temper
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Okumura Katsuya
Watanabe Tohru
Chaudhuri Olik
Kabushiki Kaisha Toshiba
Pham Long
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