Cleaning and liquid contact with solids – Processes – Including application of electrical radiant or wave energy...
Reexamination Certificate
2001-04-20
2002-09-24
Gulakowski, Randy (Department: 1746)
Cleaning and liquid contact with solids
Processes
Including application of electrical radiant or wave energy...
C134S018000, C134S019000, C134S030000, C134S036000, C134S022100, C134S902000, C216S059000, C216S064000, C216S067000, C438S905000
Reexamination Certificate
active
06453913
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of cleaning a film deposition apparatus or a vacuum processing apparatus, a method of dry etching such an apparatus, and an article production method including a process based on the cleaning or dry etching method. More particularly, the present invention relates to a method of cleaning a film deposition apparatus or a vacuum processing apparatus for forming a deposition film on a substrate to produce an electrophotographic photoreceptor or a semiconductor device such as a solar cell, a line sensor for inputting an image, an imaging device, or a TFT, a method of dry etching such an apparatus, and an article production method including a process based on either one of such methods.
2. Description of the Related Art
Various deposition films have been proposed for use in an electrophotographic photoreceptor and a semiconductor device such as a solar cell, a line sensor for inputting an image, an imaging device, and a TFT. An example is a film of amorphous silicon such as that compensated with hydrogen and/or halogen (such as fluorine or chlorine) (hereinafter referred to as “a-Si(H, X)”). Some of them are practically used. Various apparatuses and methods for depositing a film such as a-Si(H, X) are known. Specific examples of film deposition methods include vacuum evaporation, ion plating, sputtering, thermal CVD, plasma CVD, and optical CVD. Of these film deposition methods, a low-pressure method such as plasma CVD is widely used.
When a deposition film is formed on a desired substrate using one of the above methods, the film or a polymer (polysilane) in the form of particles is also deposited on some parts of a film deposition chamber. For example, when a deposition film is formed by means of the plasma CVD method using glow discharge decomposition, the deposition film is formed not only on the substrate but also on various parts other than the substrate, such as the susceptor and the opposite electrode, in the film deposition apparatus (hereinafter also referred to as a “reactor chamber”) and on the inner wall of the reactor chamber. The deposition film or polysilane is incorporated as an impurity into a film formed in the next deposition process. Such incorporation of an impurity can cause degradation of the quality of the film. Polysilane deposited on the substrate can cause the film to have a defect. As the film deposition process is repeated, the production yield greatly decreases.
One known technique to avoid the above problem is to clean the inside of the reactor chamber every one or more film deposition cycles to remove the film or polysilane deposited on parts other than where the film should be deposited. One known cleaning method is to use a chemical vapor reaction to reduce the deposited film or elements forming polysilane by means of vapor molecules. In this cleaning method, a gas such as CF
4
, NF
3
, or SF
6
is used as a cleaning gas and is supplied into the reactor chamber. The cleaning gas supplied into the reactor chamber is excited by energy of plasma, heat, or light so that the gas in the excited state reacts with elements forming the deposited film or particles, thereby converting them into vapor molecules, which are then removed by vacuum pumping means.
In recent years, ClF
3
has attracted large attention as an etching gas. ClF
3
is decomposed by low energy and is very active. The etching rate of ClF
3
is extremely high compared with the etching rates of conventional etching gases.
Various cleaning methods by means of dry etching using ClF
3
have been proposed. For example, Japanese Patent No. 2720966 discloses a cleaning method using a gas containing at least one of ClF, ClF
3
, and ClF
5
. Those methods using ClF
3
allow the cleaning to be performed in a highly efficient manner.
In recent years, there has been a need for a further improvement in image quality of electrophotographic apparatuses. In order to meet the above requirement, the resolution of developing a latent image on an electrophotographic photoreceptor has been increasingly improved.
An increase in the speed of copying machines has been also achieved. As a result, the charging process has become critical, that is, charging is needed to be performed in a shorter time. This produces a problem that when no voltage is applied to a certain portion of the surface of the photoreceptor, that portion can have a large influence upon the voltage in neighboring portions, and thus an image defect is produced in that portion.
In conventional electrophotographic apparatuses, the main purpose is to make a copy (line copy) of a document including only character information, and thus an image defect does not practically result in a significant problem. However, in recent more sophisticated copying apparatuses, it is needed to make a high-quality copy of a document including halftone information such as a picture, and an image defect which is not a significant problem in a line copy can result in a significant problem. As a result, an electrophotographic photoreceptor containing a lesser number of defects is needed for use in an electrophotographic photosensitive drum. In particular, in a certain type of electrophotographic copying machine, an image defect is visually prominent, and thus the electrophotographic photosensitive drum needs to includes a still smaller number of defects.
Thus, there has arisen a need to effectively produce an electrophotographic photoreceptor having extremely high quality with a high production yield.
However, the above-described conventional cleaning techniques for removing the undesired deposition film or polysilane remaining in the reactor chamber after forming the desired deposition film have the following problems to be solved to meet the requirements in terms of the characteristics of the articles such as a photoreceptor (photosensitive drum with a very large size).
That is, in the conventional techniques in which polysilane is removed by reacting polysilane with ClF
3
gas, the cleaning process needs a long time to remove polysilane to a sufficient degree, and thus it is needed to supply a large amount of ClF
3
and a large amount of electric power. Furthermore, the vacuum pumping means, in particular, the rotary pump, needs to continuously suck ClF
3
gas for a long time, and a large load is imposed upon the vacuum pumping means. If the removal of polysilane is not sufficient, particles remain mainly on the inner wall of the reactor chamber. It is known that the remaining particles can fly off during a subsequent film deposition process and can form defects in a deposited film.
When a large-sized product which is long in one direction (as with an electrophotographic photosensitive drum) is produced, the remaining deposition film or polysilane is nonuniformly distributed in the reactor chamber, and thus the cleaning process can become nonuniform. This can cause insufficient removal of polysilane and thus can cause the produced electrophotographic photosensitive drum to have a small image defect. Although the size and the density of defects are sufficiently low for use in conventional applications, the defects cannot be neglected in recent sophisticated apparatuses in which high resolution and high image quality are required.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide methods of cleaning and dry etching a film deposition apparatus, capable of effectively removing by-products from the inside of a reactor chamber, sufficiently to make it possible to form high-quality deposition films, and in particular, high-quality electrophotographic photosensitive drums, at a satisfactory speed.
One aspect of the present invention is a method of cleaning a film deposition apparatus for depositing a film on a substrate placed in a reactor chamber which can be evacuated to a low pressure, wherein the cleaning is performed by applying a cleaning gas and high-frequency power, and in which the application of high-frequency power is temporarily stopped in the mi
Hitsuishi Koji
Karaki Tetsuya
Katagiri Hiroyuki
Matsuoka Hideaki
Seqi Yoshio
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Kornakov M
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