Semiconductor device manufacturing: process – Coating of substrate containing semiconductor region or of... – Insulative material deposited upon semiconductive substrate
Reexamination Certificate
1999-08-25
2002-06-18
Ghyka, Alexander G. (Department: 2812)
Semiconductor device manufacturing: process
Coating of substrate containing semiconductor region or of...
Insulative material deposited upon semiconductive substrate
C438S789000
Reexamination Certificate
active
06407012
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method for manufacturing a silicon oxide film of good quality by a vapor deposition method. This silicon oxide film is suitable for an underlying layer-protecting film, a gate insulating film, an inter-layer insulating film, etc. The present invention also relates to a method for manufacturing a micro-semiconductor device of good quality (for example, metal/oxide film/semiconductor field effect transistor (MOSFET)) wherein a semiconductor surface is oxidized at a relatively low temperature of, e.g., about 800° C. or less and an extra-thin silicon oxide film (having less than about 10 nm in film thickness) of good quality is then formed. The present invention also relates to a method for manufacturing a semiconductor device (for instance, a thin film transistor) of high performance and reliability at a relatively low temperature such as around 600° C. or below. Moreover, the present invention relates to a semiconductor device of high performance and reliability manufactured thereby, and a display device (such as a liquid crystal display device) of high performance and reliability equipped with this semiconductor device. Furthermore, the present invention relates to an infrared light irradiating device for manufacturing a silicon oxide film of good quality.
2. Description of Related Art
Silicon oxide films are widely used for gate insulating films of polycrystalline silicon thin-film transistors (p-Si TFT) and gate insulating films of micro-semiconductor devices, such as VLSI having an extra-thin oxide film and the like, etc. The quality of these silicon oxide films has important effects on the electric characteristics of these semiconductor devices.
When a silicon oxide film is used for a gate insulating film of low temperature p-Si TFT, it is necessary to form a silicon oxide film at a relatively low temperature such as around 600° C. or below at which a general glass substrate can be used. Thus, a chemical vapor deposition method (CVD method) and a physical vapor deposition method (PVD method) have been conventionally applied.
Moreover, in manufacturing a micro-semiconductor device such as VLSI having an ultra thin oxide film, an ultra-thin silicon oxide film is provided by thermally oxidizing silicon at a relatively low temperature of e.g., 800° C. or below under an atmosphere containing oxygen and hydrochloric acid, or by irradiating a silicon substrate with oxygen plasma, etc.
However, these conventional silicon oxide films have a problem in that the film quality is extremely low since electric charge trapped in oxide films is large, and the like.
As a result, if a conventional silicon oxide film is used as a gate insulating film of p-Si TFT, there is a problem in that only a p-Si TFT of low quality and reliability can be provided. This is because it is easy to vary flat band voltage (Vfb) of a semiconductor device since silicon oxide films have a large amount of fixed electric charge of an oxide film, to enlarge threshold voltage (Vth) since a surface trapping level is high, and to introduce electric charge into oxide films since an oxide film trapping level is large, etc. In other words, conventional semiconductor devices such as p-Si TFT have many problems because the quality of silicon oxide films is low.
The same problems are found in a micro-semiconductor device such as VLSI with an ultra-thin silicon oxide film. Ultra-thin silicon oxide films are generally formed at a relatively low temperature of around 800° C. or below, so that they have all the problems of low temperature oxidation. More specifically, the problems are that a surface level and an oxide film trapping level are extremely high and the current of an oxide film is large. These problems are the main causes in limiting the properties of a superintegrated circuit and shortening its life.
SUMMARY OF THE INVENTION
Thus, the present invention solves the above-mentioned problems, and its objectives are to present a method for manufacturing a silicon oxide film of high quality by a vapor deposition method, to present a method for manufacturing a micro-semiconductor device such as VLSI having an ultra-thin oxide film of high quality by applying a silicon oxide film formed at a relatively low temperature such as about 800° C. or below, to present a method for manufacturing a semiconductor device (for instance, a thin film transistor) of high performance and reliability at a relatively low temperature of e.g., 600° C. or below, to present such a semiconductor device of high performance and reliability and a display device, and to present a device for manufacturing a silicon oxide film of high quality.
The present invention, first as a step of forming a silicon oxide film, deposits a silicon oxide film on various substrates such as an insulating substrate (for example, quartz glass substrate, popular non-alkali glass substrate, and the like), a semiconductor substrate (for instance, monocrystalline silicon substrate, compound semiconductor substrate, etc.) and a metal substrate by a vapor deposition method (for instance, chemical vapor deposition method (CVD) method), physical vapor deposition method (PVD method), and the like). A silicon oxide film is also formed by the oxidation of a semiconducting material surface such as by heat treatment (thermal oxidization) of a semiconducting material surface under an oxidizing atmosphere, the plasma irradiation (plasma oxidization) of an oxide material (such as oxygen and dinitrogen monoxide) to a semiconducting material surface, the supply of ozone(O
3
) (ozone oxidization), the supply of active oxygen (active oxygen oxidization) generated by a heated metal catalyst, or the like.
In the step of forming a silicon oxide film, a silicon oxide film is formed directly on a semiconductor substrate or a glass substrate as a field oxide film, a gate insulating film, an inter-layer insulating film, an underlying layer-protecting film, or the like. Furthermore, a silicon oxide film is formed on a semiconductor film, which is a pure silicon or the semiconductor having silicon as a main substance. This semiconductor film is formed in the step of forming a semiconductor film on an insulating material such as an oxide film formed on the surface of a glass substrate or a monocrystalline silicon substrate.
The semiconductor film having silicon as a main substance contains a mixture of silicon and other elements such as germanium in the film, and contains silicon at about 80% or above in percentage. Also, the pure silicon semiconductor films include silicon semiconductor films containing impurities such as P, B, Al, As and the like. Therefore, the silicon oxide films in the present invention mean not only pure silicon oxide films (SiOx films wherein x is roughly 2) but also silicon oxide films containing these elements and the oxides thereof. Silicon materials are in a monocrystalline state, polycrystalline state, amorphous state, mixed crystal state that is polycrystalline and amorphous, and the like.
The oxide film deposition step by a vapor deposition method is carried out at a relatively low temperature, around 600° C. or below. A PVD method contains a sputtering method, evaporation method, and the like. Also, a CVD method can contain an atmospheric pressure chemical vapor deposition method (APCVD method), low pressure chemical vapor deposition method (LPCVD method), plasma chemical vapor deposition method (PECVD method), and the like.
The step of forming an oxide film by thermal oxidation is carried out by treating a semiconducting material in the temperature range from around 600 to 1,000° C. under an oxidizing atmosphere containing oxygen, water vapor, hydrochloric acid, etc. In forming an ultra-thin oxide film at less than about 10 nm in film thickness, thermal oxidation is often carried out under the temperature around 800° C. or below. Also, in the step of forming an oxide film by plasma oxidation, ozone oxidation, active oxygen oxidation or the like, a semiconducting material is treated u
Miyasaka Mitsutoshi
Sakamoto Takao
Ghyka Alexander G.
Oliff & Berridg,e PLC
Seiko Epson Corporation
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