Coating apparatus – Gas or vapor deposition
Reexamination Certificate
1999-05-18
2001-05-15
Lund, Jeffrie R. (Department: 1763)
Coating apparatus
Gas or vapor deposition
C204S298070
Reexamination Certificate
active
06231672
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an apparatus for depositing thin films on a wafer such as semiconductor substrate by continuous gas injection.
2. Description of the Related Art
Referring to
FIG. 1
, a conventional thin film deposition apparatus comprises a reaction gas transfer portion
100
for transferring a reaction gas into a reactor
200
, and an exhaust portion
300
for exhausting the gas out of the reactor
200
.
The reaction gas supply portion
100
comprises a first reaction gas supply portion
110
for supplying a first reaction gas to the reactor
200
, a second reaction gas supply portion
120
for supplying a second reaction gas to the reactor
200
, and an inert gas supply portion
130
for supplying an inert gas to the reactor
200
. The exhaust portion
300
has an exhaust pump
310
for discharging the gas out of the reactor
200
.
The gas supply portions
110
,
120
and
130
and the exhaust pump
310
are connected by pipe lines having a plurality of on/off valves
111
,
112
,
113
,
114
,
115
,
121
,
122
,
123
,
124
,
125
,
131
,
132
,
133
and
134
which are controlled by a connector (not shown) connected to each of the valves.
The first reaction gas supply portion
110
includes a first source container
116
filled with a first liquid material as a source of the first reaction gas, and a mass flow controller (MFC) for controlling the flow of a transfer gas for transferring the first reaction gas to the reactor
200
. The second reaction gas supply portion
120
includes a second source container
126
filled with a second liquid material as a source of the second reaction gas, and an MFC for controlling the flow of the transfer gas for transferring the second reaction gas to the reactor
200
. The inert gas supply portion
130
comprises an inert gas container
136
for supplying the inert gas and an MFC for controlling the flow of the inert gas to the reactor
200
.
In the thin film deposition apparatus having the above structure, for example, the valves
111
,
112
and
113
are open, the transfer gas provided through a first supply line
11
and the valve
111
enters the reactor
200
together with the first reaction gas contained in the first source container
116
through the valves
112
and
113
and a first reactor pipe line
21
.
Then, when the valves
114
and
115
are open, the transfer gas provided through the first supply line
11
is discharged through the valves
114
and
115
, a first exhaust line
71
and the exhaust pump
310
.
Then, when the valves
131
,
132
and
134
are open, the inert gas flows into the reactor
200
through the first reactor pipe line
21
and a third reactor pipe line
23
, so that the reaction gas remaining in the first reactor pipe line
21
and the reactor
200
is discharged.
Then, when the valves
132
and
134
are closed an) the valves
121
,
122
and
123
are open, the transfer gas provided through a second supply line
12
and the valve
121
enters the reactor
200
together with the second reaction gas contained in the second source container
126
through the valves
122
and
123
and a second reactor pipe line
22
.
However, when the valve
134
is closed in order to transfer another reaction gas to the reactor
200
, the inert gas cannot be provided to the first reactor pipe line any more. Thus, the reaction gas remaining in the first reactor pipe line
21
, not being discharged, is mixed with the next reaction gas. Also, when the valve
132
is closed, the reaction gas in a part of the reactor
200
near the exhaust line is not discharged, so that the remaining reaction gas is mixed with the next reaction gas.
On the other hand, when the valves are turned on/off in order to transfer another reaction gas, the internal pressure of the lines connected to the corresponding valves changes. Such a change in pressure means that a stable supply of the reaction gas is not certain and causes cavitation to the supply lines, so that the transfer of the reaction gas becomes difficult.
SUMMARY OF THE INVENTION
It,is an object of the present invention to provide an apparatus for depositing thin films on a semiconductor wafer, in which the gas flow through a reactor or an exhaust pump is controlled to be constant such that different reaction gases are not mixed in the reactor.
To achieve the object of the present invention, there is provided an apparatus for depositing thin films on a semiconductor wafer, comprising: a reactor maintained at a constant pressure; at least two reaction gas supply portions for supplying reaction gases to the reactor; an exhaust pump for discharging the gases out of the reaction gas supply portions and/or the reactor; first flow control valves installed between each reaction gas supply portion and the reactor, for controlling the amount of gases flowing between the reaction gas supply portions and the reactor; second flow control valves installed between each reaction gas supply portion and the exhaust pump, for controlling the amount of gases flowing between the reaction gas supply portions and the exhaust pump; an inert gas supply portion for supplying an inert gas into the reactor; reaction gas pipe lines, wherein the reaction gases provided from the reaction gas supply portions flow through the reaction gas pipe lines to the reactor and/or the exhaust pump; an inert gas pipe line, wherein the inert gas provided from the inert gas supply portion flows through the inert gas pipe line to the reactor; and a plurality of valves installed in the reaction gas pipe lines and/or the inert gas pipe lines, for controlling the amount of reaction gases and inert gas flowing into the reactor and/or the exhaust pump.
Preferably, the first and second flow control valves are metering valves or control valves installed before the valves between the reaction gas supply portions and the reactor, and between the reaction gas supply portions and the exhaust pump. Preferably, the bypass lines have an inner diameter of 0.1~0.5 mm, and the bypass lines have a length of 15~25 mm.
REFERENCES:
patent: 4388342 (1983-06-01), Suzuki et al.
patent: 5288029 (1994-02-01), Ishibashi et al.
patent: 5575854 (1996-11-01), Jinnouchi et al.
patent: 1-140712 (1989-06-01), None
patent: 5-94949 (1993-07-01), None
Choi Won-sung
Lee Sang-Jin
IPS Ltd.
Lund Jeffrie R.
MacArthur Sylvia R.
Nixon & Vanderhye PC
Presta Frank P.
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