Semiconductor device manufacturing: process – Coating with electrically or thermally conductive material – To form ohmic contact to semiconductive material
Reexamination Certificate
1999-06-16
2002-01-01
Smith, Matthew (Department: 2825)
Semiconductor device manufacturing: process
Coating with electrically or thermally conductive material
To form ohmic contact to semiconductive material
C438S681000, C438S758000, C438S799000
Reexamination Certificate
active
06335281
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a deposited film forming process and a deposited film forming apparatus. More particularly, it relates to a deposited film forming process and a deposited film forming apparatus which are suited for stably forming light-receiving members having a sensitivity to electromagnetic waves such as light (which herein refers to light in a broad sense and indicates ultraviolet rays, visible rays, infrared rays, X-rays, &ggr;-rays, etc.).
2. Related Background Art
Materials that form photoconductive layers in solid-state image pick-up devices or in electrophotographic light-receiving members in the field of image formation or in character readers are required to have properties as follows: They are highly sensitive, have a high SN ratio (photocurrent (Ip)/(Id)), have absorption spectra suited to spectral characteristics of electromagnetic waves to be radiated, have a high response to light, have the desired dark resistance and are harmless to human bodies when used; and also, in the solid-state image pick-up devices, the materials are required to have properties that enable easy erasure of the lag in a prescribed time. In particular, in the case of light-receiving members of electrophotographic apparatus used as business machines in offices, the harmlessness in their use is important.
Materials that attract notice from such viewpoints include amorphous silicon (hereinafter “a-Si) whose dangling bonds have been modified with monovalent elements such as hydrogen or halogen atoms, and its application to electrophotographic light-receiving members is disclosed in, e.g., Japanese Patent Application Laid-Open No. 54-86341.
Electrophotographic light-receiving members are known to have various forms. Those having the form of what is called a drum are commonly used. In this case, the desired layers such as photoconductive layers, i.e., light-receiving layers are formed on the surfaces of cylindrical substrates to form light-receiving members.
When light-receiving layers comprised of a-Si are formed on cylindrical substrates, many processes are known in the art, as exemplified by sputtering, a process in which material gases are decomposed by heat (thermal CVD), a process in which material gases are decomposed by light (photo-assisted CVD) and a process in which material gases are decomposed by plasma (plasma-assisted CVD). In particular, one having been put into practical use in a very advanced state is plasma CVD (chemical vapor deposition), i.e., a process in which material gases are decomposed by direct-current or high-frequency or microwave glow discharging to form deposited films on the cylindrical substrate.
FIG. 1
is a cross-sectional schematic view showing an example of a plasma CVD system. In
FIG. 1
, reference numeral
6100
denotes the whole of a vacuum reactor;
6111
a cathode electrode serving also as the sidewall of the vacuum reactor;
6123
a gate that forms the top wall of the vacuum reactor; and
6121
the bottom wall of the vacuum reactor. The cathode electrode
6111
the top wall
6123
and the bottom wall
6121
are each insulated with an insulator
6122
Reference numeral
6112
denotes a cylindrical, film-forming substrate (herein meant to be a target substrate on which the deposited film is to be formed) set on an auxiliary substrate
6113
-
a
made of a metal such as aluminum, and disposed in the vacuum reactor. The film-forming substrate
6112
is fitted with an auxiliary-substrate cap
6113
-
b
at the top end thereof. The film-forming substrate
6112
is grounded to serve as the anode electrode. In the auxiliary substrate
6113
-
a,
a substrate heater
6114
is disposed so as to be used to maintain the film-forming substrate at a prescribed temperature during film formation or to anneal the film-forming substrate after film formation.
Reference numeral
6115
denotes a deposited film forming material gas feed pipe, and is provided with a large number of gas release holes (not shown) through which material gases are released into the vacuum reaction space. At the other end of the material gas feed pipe
6115
, the pipe communicates with a deposited film forming material gas feed system
6200
via a gas feed pipe
6117
and a valve
6260
.
Reference numeral
6124
is an exhaust pipe through which the inside of the vacuum reactor is evacuated, and communicates with a vacuum exhaust system (not shown) via an exhaust valve
6119
. A vacuum gauge
6120
is connected to the exhaust pipe
6124
, and a reactor leak valve
6118
used when, e.g., the inside of the vacuum reactor is set open to the atmosphere is also connected to the exhaust pipe
6124
. Reference numeral
6111
denotes a means for applying electric power to the cathode electrode
6111
.
The deposited film forming material gas feed system
6200
has material gas cylinders
6221
to
6226
holding the desired material gases. The gas cylinders
6221
to
6226
are connected to their piping via valves
6231
to
6236
so that material gases can be flowed into mass flow controllers
6211
to
6216
via flow-in valves
6241
to
6146
, respectively. From the mass flow controllers
6211
to
6216
, the piping is so connected as to come to meet in the valve
6240
via flow-out valves
6251
to
6256
. Pressure controllers
6261
to
6266
are connected between the material gas cylinders
6221
to
6226
and the flow-in valves
6241
to
6146
, respectively, in the piping.
Such a deposited film forming apparatus employing plasma CVD is operated in the following way.
The inside of the vacuum reactor is evacuated through the exhaust pipe
6124
, and also the film-forming substrate
6112
is heated to and kept at a prescribed temperature by means of the heater
6114
. Next, through the material gas feed pipe
6115
, when, e.g., a-Si deposited films are formed, material gases such as silane are introduced into the vacuum reactor. The material gases are released from the material gas release holes (not shown) of the gas feed pipe into the vacuum reactor. Concurrently therewith, from a voltage applying means
6116
, for example a high frequency power is applied across the cathode electrode
6111
and the film-forming substrate (anode electrode)
6112
to cause plasma discharge to take place. Thus, the material gas inside the vacuum reactor is excited into excited species, where radical particles, electrons and ionic particles of Si* and SiH* (the mark * indicates an excited state) are produced and a deposited film is formed on the film-forming substrate surface by chemical mutual action between these particles themselves or between these particles and the film-forming substrate surface.
In such an instance where an electrophotographic light-receiving member comprised of, e.g., a-Si, an auxiliary substrate is inserted into the film-forming cylindrical substrate because the film-forming cylindrical substrate must be transported into the vacuum reactor and held there. Such an auxiliary substrate is also commonly inserted into the film-forming cylindrical substrate because, as disclosed in, e.g., Japanese Patent Application Laid-Open No. 60-86276, auxiliary substrates must be provided at the upper and lower part of a film-forming substrate so that its characteristics can be made uniform. Still also, e.g., Japanese Patent Application Laid-Open No. 7-181700 discloses a technique in which, for the purpose of preventing faulty images, achieving an improvement in electrophotographic performance and obtaining much uniform and high-quality images, the auxiliary substrate is basically so constituted that a material having a great thermal conductivity is used at its part facing the film-forming substrate and a material having a small coefficient of thermal expansion and a small thermal conductivity is used at the upper part and/or lower part of the auxiliary substrate.
As another example, Japanese Patent Application Laid-Open No. 7-230178 discloses a technique in which, for the purpose of preventing faulty images, achieving an improvement in electrophotogr
Katagiri Hiroyuki
Matsuoka Hideaki
Segi Yoshio
Takai Yasuyoshi
Smith Matthew
Yevsikov V.
LandOfFree
Deposited film forming process does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Deposited film forming process, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Deposited film forming process will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2819470