U.S. patent application number 10/970172 was filed with the patent office on 2005-03-17 for cold wall chemical vapor deposition apparatus and cleaning method of a chamber for the same.
Invention is credited to Choi, Kyu-Jin, Lee, Tae-Wan, Lee, Yong-Ho.
Application Number | 20050056223 10/970172 |
Document ID | / |
Family ID | 19708424 |
Filed Date | 2005-03-17 |
United States Patent
Application |
20050056223 |
Kind Code |
A1 |
Lee, Tae-Wan ; et
al. |
March 17, 2005 |
Cold wall chemical vapor deposition apparatus and cleaning method
of a chamber for the same
Abstract
A cold wall chemical vapor deposition apparatus includes: a
chamber; a susceptor movable up and down in the chamber by a
driving means, the susceptor including a heater and an internal
electrode; a heat reflector over the susceptor, the heat reflector
reflecting a heat emitted from the heater back to a wafer on the
susceptor and serving as an correspondent electrode to the internal
electrode; a heater control unit connected to the wafer, the heater
and the driving means, the heater control unit sensing a
temperature of the wafer, the susceptor moving according to the
temperature; a gas supply unit supplying gases to the chamber; and
a power source applying a voltage to the chamber.
Inventors: |
Lee, Tae-Wan; (Seoul,
KR) ; Choi, Kyu-Jin; (Seoul, KR) ; Lee,
Yong-Ho; (Gyeonggi-do, KR) |
Correspondence
Address: |
DUANE MORRIS LLP
P. O. BOX 1003
305 NORTH FRONT STREET, 5TH FLOOR
HARRISBURG
PA
17108-1003
US
|
Family ID: |
19708424 |
Appl. No.: |
10/970172 |
Filed: |
October 21, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10970172 |
Oct 21, 2004 |
|
|
|
10124252 |
Apr 17, 2002 |
|
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Current U.S.
Class: |
118/729 ;
118/725 |
Current CPC
Class: |
C23C 16/4404 20130101;
C23C 16/4405 20130101; C23C 16/46 20130101 |
Class at
Publication: |
118/729 ;
118/725 |
International
Class: |
C23C 016/00 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 18, 2001 |
KR |
2001-20847 |
Claims
1.-5. (Cancelled)
6. A cleaning method of a chamber for a cold wall chemical vapor
deposition apparatus, which includes a susceptor having an internal
electrode, a heat reflector, a driving means for the susceptor, a
power source selectively applying a voltage to the heat reflector
or to the internal electrode and a gas supply unit, comprising:
supplying cleaning gas from the gas supply unit to the chamber;
applying the voltage to the heat reflector and simultaneously
grounding the internal electrode; applying the voltage to the
internal electrode and simultaneously grounding the heat reflector;
and moving the susceptor up and down by the driving means while the
voltage is applied to the heat reflector or to the internal
electrode.
7. The method according to claim 6, wherein the driving means is a
motor.
8. The method according to claim 6, wherein the cold wall chemical
vapor deposition apparatus further includes a switch selectively
applying the voltage to the heat reflector or to the internal
electrode.
9. A cleaning method of a chamber for a cold wall chemical vapor
deposition apparatus, which includes a susceptor having an internal
electrode, a heat reflector, a power source selectively applying a
voltage to the heat reflector or to the internal electrode and a
gas supply unit, comprising: supplying cleaning gas from the gas
supply unit to the chamber; and applying the voltage to the heat
reflector.
10. The method according to claim 9, further comprising grounding
the internal electrode simultaneously with applying the voltage to
the heat reflector.
11. The method according to claim 9, wherein the cold wall chemical
vapor deposition apparatus further includes a driving means for the
susceptor.
12. The method according to claim 11, wherein the driving means is
a motor.
13. The method according to claim 11, further comprising grounding
the internal electrode simultaneously with applying the voltage to
the heat reflector.
14. The method according to claim 6, wherein the cold wall chemical
vapor deposition apparatus further includes a switch selectively
applying the voltage to one of the heat reflector and the internal
electrode.
Description
[0001] This application claims the benefit of Korean Patent
Application No. 2001-20847, filed on Apr. 18, 2001 in Korea, which
is hereby incorporated by reference for all purposes as if fully
set forth herein.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to an apparatus for
manufacturing semi-conductor and more particularly, to a cold wall
chemical vapor deposition apparatus and a cleaning method of a
chamber for the same.
[0004] 2. Discussion of the Related Art
[0005] A development for a new material has been actively performed
in the field and diverse large-scale integrated circuit (LSI) such
as ultra large-scale integrated circuit (ULSI) has been developed
thanks to a rapid growth of the new material development. That is,
because the new material for forming thin films such as an
insulating layer, a semi-conductor layer and a conductor layer,
which constitute a semi-conductor device, has been developed widely
in the field, the large-scale integrated circuit (LSI) such as the
ultra large-scale integrated (ULSI) circuit is available now. As
the society proceeds to the information age, an electric goods,
which has a low weight, a small size and a thin dimension, has been
required in the field. Because structural elements of the
semi-conductor device requires a high reliability, a thin film
forming method, which satisfies conditions such as a uniform
deposition, a superior step coverage and a complete removal of
particles, is required. Accordingly, many thin film deposition
methods such as a chemical vapor deposition (CVD) method and a
physical vapor deposition (PVD) method have been developed in the
field.
[0006] Because the chemical vapor deposition method has many
advantages compared with other deposition methods, it has usually
been used for a manufacturing method of the semi-conductor device.
A selective epitaxial growth (SEG) method in which a thin film is
formed by growing a crystal grain selectively on a particular
region of a substrate using the chemical vapor deposition method,
is used in a manufacturing process for an integrated circuit such
as the large-scale integrated circuit (LSI) or above the large
scale integrated circuit (LSI). The selective epitaxial growth
method is now used particularly in the integrated circuit
manufacturing process in which an insulating film such as silicon
oxide (SiO.sub.2) or silicon nitride (Si.sub.3N.sub.4) is formed in
line patterns on a silicon substrate and a silicon film is
selectively accumulated in an exposed region of the silicon
substrate.
[0007] FIG. 1 is a schematic plan view of a conventional hot wall
chemical vapor deposition apparatus. The hot wall chemical vapor
deposition apparatus 2 is one of apparatuses that perform the
selective epitaxial growth process of the silicon. The hot wall
chemical vapor deposition apparatus 2 includes a chamber 4 and a
wall of the chamber 4 is heated by three-zone resistance heater 6.
A forming process of the silicon thin film on a wafer in the hot
wall chemical vapor deposition apparatus is as follows. First, a
wafer is loaded into the chamber 4 of the hot wall chemical vapor
deposition apparatus 2 and subsequently source gas, which will grow
into the thin film, is supplied into the chamber 4. The chamber 4
is then heated by the three-zone resistance heater 6. The silicon
thin film is subsequently formed on the wafer by growing silicon
crystals on the wafer under high temperature condition in the
chamber 4. At this time, because the wall of the chamber 4 is
heated to a high temperature, the source gas is undesirably
deposited thin on an inner surface of the chamber wall. The
deposition of the source gas on the inner surface of the chamber 4
has disadvantages as followings. First, it increases a loss of
material due to an unintentional deposition. Second, a rupture of
the chamber 4 may occur when the chamber 4 is cooled down after a
completion of the depositing process because of a contraction ratio
difference between the chamber wall and the thin film deposited on
the chamber wall. Third, because interior condition of the chamber
4 is under high temperature, the source gas such as silane
(SiH.sub.4) or disilane (Si.sub.2H.sub.6), which is deposited on
the chamber inner wall, is actively gasified and thus decreases a
growing speed of the silicon crystal on the insulating film such as
silicon oxide (SiO.sub.2) or silicon nitride (Si.sub.3N.sub.4). For
this reason, it is difficult to grow the silicon crystal over 500
.ANG. under the condition like this. Therefore, a cold wall
chemical vapor deposition apparatus has been suggested to overcome
these problems.
[0008] The cold wall chemical vapor deposition apparatus includes a
chamber and a susceptor in the chamber. The susceptor includes a
heater in it. After an interior of the chamber is vacuumed, the
heater of the susceptor is turned on to heat up the susceptor. When
the susceptor is heated by the heater, the wafer on the susceptor
is also heated indirectly.
[0009] FIG. 2 is a cross-sectional view illustrating a conventional
cold wall chemical vapor deposition apparatus. The conventional
cold wall chemical vapor deposition apparatus 20 includes a chamber
22, exhaust units 28 and 30 and a gas supply unit 24. The chamber
22 is a place where the thin film deposition is performed and is
electrically grounded. The susceptor 36 is positioned in the
chamber 22 and the wafer 34, which is formed of silicon material,
is loaded on the susceptor 36. The exhaust units 28 and 30 are for
exhausting the air in the chamber 22. The gas supply unit 24 is for
storing the source gas and providing the source gas into the
chamber 22. The exhaust units 28 and 30 consist of a first exhaust
unit 30 and a second exhaust unit 28. The first exhaust unit 30 is
for whole region of the interior of the chamber 22 and the second
exhaust unit 28 is mainly for a surrounding of the susceptor 36. An
ultra-high vacuum (UHV) exhaust system, which uses a turbo
molecular pump, is included in the exhaust units 28 and 30 and thus
the interior of the chamber 22, particularly the surrounding of the
susceptor 36 where the thin film deposition process is performed,
comes to be in ultra high vacuum state. The susceptor 36 is fixed
to a bottom of the chamber 22 and the wafer 34 on which the thin
film is to be deposited is put on the susceptor 36. The susceptor
36 is generally made of silicon material, which is also a material
for the wafer, such as graphite or silicon carbide (SiC), for
example, not to damage the wafer 34. The susceptor 36 includes the
heater 37 and an internal electrode 38. A heat reflector 32 is
formed over the susceptor 36 with same material as the thin film on
the wafer 34. The heat reflector 36 reflects a radiant heat that is
emitted from the wafer 34 and the susceptor 36 back to the wafer 34
to improve a heating efficiency for the wafer 34 in the chamber 22.
The thin film material is undesirably deposited on the heat
reflector 32 as well as on the wafer during the thin film
depositing process, and accordingly the heat reflector 32 is formed
of the same material as the thin film material on the wafer 34 to
prevent the thin film material deposited on the heat reflector 32
from being easily separated away from the heat reflector 32. A
radio-frequency (RF) electrode 33, which serves to form an electric
field between the radio-frequency (RF) electrode 33 and the
internal electrode 38 by a radio-frequency (RF) power supply 35, is
formed in the heat reflector 32. The cold wall chemical vapor
deposition apparatus 20 may further include a refrigerating device
to cool down the wall of the chamber 22.
[0010] The thin film deposition process in the cold wall chemical
vapor deposition apparatus will be described hereinafter with
reference to FIG. 2 and FIG. 3. The wafer 34 is carried into the
chamber 22 from outside through a slot valve 26 and then is loaded
onto the susceptor 36. The interior state of the chamber 22
subsequently becomes an ultra high vacuum state of 10.sup.-8 Torr
by the first exhaust unit 30 and the second exhaust unit 28.
Because the susceptor 36 was already heated by the heater 37 before
the loading of the wafer on the susceptor 36, the wafer 34 is
heated up to a certain temperature, usually about 700.degree. C.,
and then the source gas is supplied into the chamber 22 through the
gas supply unit 24. At this time, the interior of the chamber 22 is
under the ultra high vacuum state and accordingly the source gas
reaches the wafer 34 by being scattered in the chamber 22. Because
the wafer 34 was heated up by the heater 37 in the susceptor 36,
the source gas is resolved into its components as it reaches a
surface of the wafer 34 and then deposited on the wafer 34. A line
pattern is usually formed on the surface of the wafer 34 using the
insulating film such as silicon oxide (SiO.sub.2) film or silicon
nitride (Si.sub.3N.sub.4) film, for example. The surface of the
wafer 34 includes a surface region where the silicon, which is the
material for the wafer 34, is exposed to the air and a surface
region where the insulating film such as silicon oxide (SiO.sub.2)
film or silicon nitride (Si.sub.3N.sub.4) film is exposed to the
air. Because the reaction rate on the silicon surface is much
faster than the reaction rate on the silicon oxide (SiO.sub.2) film
surface or the silicon nitride (Si.sub.3N.sub.4) film surface, the
silicon is selectively accumulated only on the silicon surface of
the wafer 34.
[0011] The cold wall chemical vapor deposition apparatus 20 in
which the silicon crystals are selectively grown on the surface of
the wafer 34, has a few disadvantages as followings. First, the
thin film may not be formed on the surface of the wafer uniformly
due to an irregular heating of the wafer 34. That is, the cold wall
chemical vapor deposition apparatus includes only the heater 37 in
the susceptor 36 for its heating source and accordingly there
occurs a temperature difference between a top surface of the wafer
34 and a bottom surface of the wafer 34. This temperature
difference between the top surface and the bottom surface causes an
irregular temperature distribution through the whole wafer 34 and
thus causes a different silicon crystal growth depending on a
region of the wafer 34. Because a deposition speed of the source
gas on the wafer surface is in proportion to the temperature of the
wafer 34, the different temperature distribution of the wafer 34
causes that the thin film is not formed uniformly on the wafer 34.
If other elements are already formed on the wafer 34, the irregular
deposition phenomenon becomes more serious because of a step of
other elements. For example, a deposition speed of polysilicon
shows a 2.0 to 2.5 percent difference when there is a temperature
difference of 1.degree. C. FIG. 3 is a graph illustrating a
temperature difference between the wafer 34 and a cold wall in a
conventional cold wall chemical vapor deposition apparatus 20. As
shown in the figure, a temperature of the cold wall is usually
maintained at about 20.degree. C. and a temperature of the
susceptor 36 is usually maintained at about 700.degree. C.
Accordingly, there is a temperature difference of 25.degree. C.
between the top surface and the bottom surface of the wafer 34,
which contacts the susceptor 36.
[0012] Another disadvantage of the cold wall chemical vapor
deposition apparatus 20 is that the thin film may also be formed
undesirably on the heat reflector 32 and then separated away from
the heat reflector 32 serving as a contaminating material. That is,
if a thickness of the thin, which is deposited on the heated
reflector 32 during a repeated deposition process, becomes thick,
the deposited thin film on the heat reflector 32 comes to be
separated away from the heat reflector 32 due to its weight and
floats around as particles in a shape of dust in the chamber 22. If
these particles of the separated thin film sticks to the elements
on the wafer 34, they act as impurities and thus lower a
reliability of the elements of the wafer 34.
SUMMARY OF THE INVENTION
[0013] Accordingly, the present invention is directed to a cold
wall chemical vapor deposition apparatus and a cleaning method of a
chamber for the same that substantially obviates one or more of
problems due to limitations and disadvantages of the related
art.
[0014] An advantage of the present invention is to provide a cold
wall chemical vapor deposition apparatus in which a susceptor can
move up and down during thin film deposition process to overcome
irregular thin film deposition on a wafer and to provide a heat
reflector on which a window that is coated or formed with quartz or
silicon oxide (SiO.sub.2) is formed.
[0015] Another advantage of the present invention is to provide a
cleaning method of a chamber of a cold wall chemical vapor
deposition apparatus in which a susceptor moves up and down and a
movement direction of cleaning gas such as sulfur hexafluoride
(SF.sub.6) plasma gas is changed by a switching operation of
electrodes to clean the chamber more efficiently than a
conventional cleaning method.
[0016] Additional features and advantages of the invention will be
set forth in the description which follows, and in part will be
apparent from the description, or may be learned by practice of the
invention. The objectives and other advantages of the invention
will be realized and attained by the structure particularly pointed
out in the written description and claims hereof as well as the
appended drawings.
[0017] To achieve these and other advantages and in accordance with
the purpose of the present invention, as embodied and broadly
described, a cold wall chemical vapor deposition apparatus
includes: a chamber; a susceptor movable up and down in the chamber
by a driving means, the susceptor including a heater and an
internal electrode; a heat reflector over the susceptor, the heat
reflector reflecting a heat emitted from the heater back to a wafer
on the susceptor and serving as an correspondent electrode to the
internal electrode; a heater control unit connected to the wafer,
the heater and the driving means, the heater control unit sensing a
temperature of the wafer, the susceptor moving according to the
temperature; a gas supply unit supplying gases to the chamber; and
a power source applying a voltage to the chamber.
[0018] In another aspect, a cleaning method of a chamber for a cold
wall chemical vapor deposition apparatus, which includes a
susceptor having an internal electrode, a heat reflector, a driving
means for the susceptor, a power source selectively applying a
voltage to the heat reflector or to the internal electrode and a
gas supply unit includes: supplying cleaning gas from the gas
supply unit to the chamber; applying the voltage to the heat
reflector and simultaneously grounding the internal electrode;
applying the voltage to the internal electrode and simultaneously
grounding the heat reflector; and moving the susceptor up and down
by the driving means while the voltage is applied to the heat
reflector or to the internal electrode.
[0019] It is to be understood that both the foregoing general
description and the following detailed description are exemplary
and explanatory and are intended to provide further explanation of
the invention as claimed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] The accompanying drawings, which are included to provide a
further understanding of the invention and are incorporated in and
constitute a part of this specification, illustrate embodiments of
the invention and together with the description serve to explain
the principles of the invention.
[0021] In the drawings:
[0022] FIG. 1 is a schematic plan view of a conventional hot wall
chemical vapor deposition apparatus;
[0023] FIG. 2 is a cross-sectional view illustrating a conventional
cold wall chemical vapor deposition apparatus;
[0024] FIG. 3 is a graph illustrating a temperature difference
between a wafer and a cold wall in a conventional cold wall
chemical vapor deposition apparatus; and
[0025] FIG. 4 is a cross-sectional view illustrating a cold wall
chemical vapor deposition apparatus according to the present
invention.
DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS
[0026] Reference will now be made in detail to the illustrated
embodiment of the present invention, which is illustrated in the
accompanying drawings.
[0027] The characteristic of the present invention is that a cold
wall chemical vapor deposition apparatus includes a movable
susceptor, a heat reflector that has a window on it and a heater
control unit. The susceptor of the present invention can move up
and down to reduce a temperature difference between a top surface
and a bottom surface of a wafer. The window of the heat reflector
is formed on the heat reflector to control thin film material not
to be deposited on the heat reflector. The heater control unit
controls a temperature of the heater and a movement of the
susceptor.
[0028] FIG. 4 is a cross-sectional view illustrating a cold wall
chemical vapor deposition apparatus according to the present
invention. As shown in the figure, the cold wall chemical vapor
deposition apparatus 50 includes a chamber 52, exhaust units 58 and
60 and a gas supply unit 54. The chamber 52 is electrically
grounded. The exhaust units 58 and 60 are for exhausting the air in
the chamber 52. The gas supply unit 54 is for supplying source gas
material into the chamber 52. The exhaust units consist of a first
exhaust unit 60 and a second exhaust unit 58. The first exhaust
unit 30 is for whole region of an interior of the chamber 52 and
the second exhaust unit 58 is mainly for a surrounding of the
susceptor 66. An ultra-high vacuum (UHV) exhaust system, which uses
a turbo molecular pump, is included in the exhaust units 58 and 60
and thus the interior of the chamber 52, particularly the
surrounding of the susceptor 66 where the thin film deposition
process is performed, becomes an ultra high vacuum state. The
susceptor 66 is positioned in the chamber 52 and supported by a
supporter 68. A wafer 64 on which the thin film is deposited is put
on the susceptor 66. The susceptor 66 is desirably made of silicon
material, which is a material for the wafer, such as graphite or
silicon carbide (SiC), for example, not to damage the wafer 64. The
susceptor 66 has a heater 67, which is for heating the wafer 64 on
the susceptor 66, and an internal electrode 69, which serves as one
of electrodes to form an electric filed in the chamber 52. The
susceptor 66 can move up and down and the movement of the susceptor
66 is driven by a motor 70 that is connected to the supporter 68. A
heat reflector 62 is positioned over the susceptor 66 in the
chamber 52 to increase a heating efficiency for the wafer 64 by
reflecting a radiant heat that is emitted from the wafer 64 and the
susceptor 66 back to the wafer 64. The heat reflector 62 is formed
of metal material and serves as another electrode to which a
radio-frequency (RF) voltage is applied to form the electric field
in the chamber 52. The window 63 is coated or formed with material
such as quartz or silicon oxide (SiO.sub.2) on the heat reflector
62 to prevent the thin film material from being accumulated on the
heat reflector 62. The cold wall chemical vapor deposition
apparatus of the present invention further includes a heater
control unit 65, which controls a temperature of the heater 67 and
the movement of the susceptor 66 upward or downward after sensing a
temperature of the wafer 64. The heater control unit 65 may be
disposed in the chamber 52 but it is preferable to dispose it
outside of the chamber 52.
[0029] The electrical structure of the cold wall chemical vapor
deposition apparatus will be described hereinafter. The internal
electrode 69 of the susceptor 66 and the heat reflector, i.e., an
external electrode, are connected to a radio-frequency (RF) power
source 82 that is controlled by a switch 80. The switch 80
selectively applies the radio-frequency (RF) voltage to one of
electrodes, i.e., the internal electrode 69 or the heat reflector
62, and simultaneously ground the other electrode left. That is, if
the radio-frequency voltage is applied to the internal electrode
69, then the heat reflector 62 is grounded and if the
radio-frequency voltage is applied to the heat reflector 62, the
internal electrode 69 is grounded. A selective application of the
radio-frequency (RF) voltage and the grounding is controlled by the
switch 80.
[0030] A thin film depositing process of the present invention will
be described hereinafter with reference to FIG. 4. The wafer 64 is
carried into the chamber 52 from outside through a slot valve 56
and then is loaded onto the susceptor 66. The interior state of the
chamber 52 subsequently becomes an ultra high vacuum state of
10.sup.-8 Torr by the first exhaust unit 60 and the second exhaust
unit 58. Because the susceptor 66 was already heated by the heater
67 before the wafer is loaded on the susceptor 66, the wafer 64 is
heated up to a certain temperature, usually about 700.degree. C.,
and then the source gas is supplied into the chamber 52 through a
gas supply unit 54. The source gas can reach the wafer 64 by being
scattered in the chamber 52 because the interior of the chamber 52
is under the ultra high vacuum state. At this time because the
wafer 64 was already heated up by the heater 67 in the susceptor 66
as mentioned above, the source gas is resolved into its components
as it reaches a surface of the wafer 64 and then deposited on the
wafer 64. A line pattern is usually formed on a surface of the
wafer 64 using the insulating film such as silicon oxide
(SiO.sub.2) film or silicon nitride (Si.sub.3N.sub.4) film, for
example. The surface of the wafer 64 includes a surface region
where the silicon, which is a material for the wafer 64, is exposed
to the air and a surface region where the insulating film such as
silicon oxide (SiO.sub.2) film or silicon nitride (Si.sub.3N.sub.4)
film is exposed to the air. Because the reaction rate on the
silicon surface is much faster than the reaction rate on the
silicon oxide (SiO.sub.2) film surface or the silicon nitride
(Si.sub.3N.sub.4) film surface, the silicon is selectively
accumulated only on the silicon surface of the wafer 64.
[0031] The cold wall chemical vapor deposition apparatus 50
includes the movable susceptor 66, which moves up and down by the
motor 70, and the heater control unit 65, which controls an
operation of the motor 70. If a big temperature difference between
a top surface of the wafer 64 and a bottom surface of the wafer 64
is sensed by the heater control unit 65, the heater control unit 65
controls the motor 70 to move up the susceptor 66 toward the heat
reflector 62 and controls a temperature of the heater 67 to reduce
the temperature difference between the top surface of the wafer 64
and the bottom surface of the wafer 64.
[0032] On the other hand, if a temperature of the wafer 64 becomes
too high, the heater control unit 65 senses this and then controls
the motor 70 to move the susceptor 66 down. The heater control unit
65 simultaneously controls the temperature of the heater 67 to let
the wafer maintain a proper temperature. That is, the temperature
of the wafer 64 can be controlled by the movement of the susceptor
66 and the temperature control of the heater 67 and thus the
temperature control of the wafer is much more effective in the
present invention compared with the conventional cold wall chemical
vapor deposition apparatus in which the temperature control of the
wafer is done only by the heater. In addition, because the heat
reflector 62 has the window 63 on it and the window 63 is coated or
formed using quartz or silicon oxide (SiO.sub.2), an undesirable
thin film deposition phenomenon on the heat reflector 62 can be
decreased remarkably.
[0033] A cleaning process of the chamber 52 is performed after the
thin film deposition process. The cold wall chemical vapor
deposition apparatus of the present invention is also superior in a
cleaning-process of the chamber. The cleaning process of the
chamber 52 according to the present invention will be described
hereinafter. The cleaning process of the chamber in the
conventional cold wall chemical vapor deposition apparatus is
generally performed in a way that an electric field is formed in
the chamber by applying the radio-frequency (RF) voltage to the
heat reflector and then cleaning gas such as sulfur hexafluoride
(SF.sub.6) plasma gas is supplied into the chamber. The cleaning
process of the present invention is also performed using the
cleaning gas such as sulfur hexafluoride (SF.sub.6) plasma gas.
However, because the susceptor 66 of the present invention is
movable up and down, a density and a distribution of the cleaning
gas such as sulfur hexafluoride (SF.sub.6) plasma gas, which is
between the heat reflector 62 and the susceptor 66, can be
controlled by the movement of the susceptor 66. Accordingly, the
cleaning of the chamber 52 can be performed more efficiently in the
present invention than the conventional cold wall chemical vapor
deposition apparatus that has a fixed susceptor 66.
[0034] As described before, the cold wall chemical vapor deposition
apparatus 50 includes two electrodes to form electric field in the
chamber, one is the heat reflector 62 and the other is the internal
electrode 69. Besides the cold wall chemical vapor deposition
apparatus 50 further includes the switch 80. The switch 80
selectively applies the radio-frequency (RF) voltage to one of two
electrodes and simultaneously grounds the other electrode left.
That is, if the radio-frequency voltage is applied to the internal
electrode 69, then the heat reflector 62 is grounded and if the
radio-frequency voltage is applied to the heat reflector 62, the
internal electrode 69 is grounded. The selective application of the
radio-frequency (RF) voltage and the grounding is controlled in
this manner by the switch 80. Accordingly, if the switching
operation of the electrodes is performed during the cleaning
process of the chamber 52, a movement direction of the plasma gas
is changed into an opposite direction. If the switching operation
of the electrodes is performed repeatedly, the plasma gas, which
has an opposite movement direction, can be generated repeatedly in
the chamber and accordingly the cleaning of the chamber 52 can be
performed more efficiently than a conventional cleaning method that
uses a plasma gas moving in a single direction.
[0035] It will be apparent to those skilled in the art that various
modifications and variation can be made in the fabrication and
application of the present invention without departing from the
spirit or scope of the invention. Thus, it is intended that the
present invention cover the modifications and variations of this
invention provided they come within the scope of the appended
claims and their equivalents.
* * * * *