Heat exchange – With timer – programmer – time delay – or condition responsive... – Having heating and cooling capability
Reexamination Certificate
2000-05-03
2002-09-24
Bueker, Richard (Department: 1763)
Heat exchange
With timer, programmer, time delay, or condition responsive...
Having heating and cooling capability
C165S218000, C165S048100, C165S050000, C118S715000, C118S724000, C118S725000, C118S666000, C239S132100, C239S132300, C239S135000, C239S139000
Reexamination Certificate
active
06453992
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an apparatus for processing a substrate for a semiconductor wafer or a LCD(Liquid Crystal Display), and in particular to a gas distributor for the above-described apparatus.
2. Description of the Background Art
A semiconductor device or LCD is fabricated by repeatedly performing a process for forming a thin film on a semiconductor wafer or LCD substrate and etching a part of the thin film.
Therefore, the thin film formation process and etching process are important processes for fabricating the semiconductor device and LCD. As a representative method for forming the above-described thin film, a CVD(Chemical Vapor Deposition) method is known, and as a process for etching the thin film, a RIE(Reactive Ion Etching) method is known.
In the chemical vapor deposition process and active ion etching process, a certain gas is filled in the process chamber. A chemical reaction between gases or a chemical reaction between a wafer in the reaction furnace or a substrate material and the gas is performed. Therefore, in the chemical vapor deposition apparatus or active ion etching apparatus, a gas distributor which is capable of uniformly distributing in the direction of a certain destination, namely, the wafer or the substrate at a certain speed and under a pressure is used. The present invention relates to the above-described gas distributor.
In particular, in the chemical vapor deposition apparatus, the gas distributor is an important element for obtaining a good quality thin film which has a uniform thickness on the semiconductor wafer or LCD substrate and does not contain particles. The following conditions are required.
Namely, first, gas must be uniformly distributed over the wafer or substrate, and second, a chemical reaction should be stably performed in the interior of the gas distributor or on the outer surface by obtaining or maintaining an activated energy of the gas before the gas is distributed in the direction of a work stand, on which the wafer is placed, from the gas distributor or after the gas is distributed. Namely, the reaction is guided to occur on a destination material, namely, on the wafer.
In particular, in the MOCVD(Metal Organic Chemical Vapor Deposition) method for depositing the organic metal thin film which is widely used, the temperature stability and uniformity of a source gas are affected by the characteristic of the thin film. However, in the gas distributor of the chemical vapor deposition apparatus which is widely used, it is difficult to obtain a good quality film.
FIG. 1
is a cross-sectional view illustrating the interior of a reaction furnace of the conventional chemical vapor deposition apparatus. As shown therein, the reaction furnace is surrounded by a cylindrical outer wall
10
, and a gas distributor
11
is installed at an upper portion of the cylindrical outer wall
10
, and a gas outlet tube
15
is provided at the bottom. A gas inlet tube
12
is provided on the upper surface of the gas distributor
11
through which gas is introduced. A work stand
13
is placed in the interior of the reaction furnace surrounded by the outer wall
10
and below the gas distributor
11
. A wafer W is placed on the upper surface of the work stand
13
, and a heating apparatus
14
is installed below the work stand. A gas outlet portion
15
is connected at the lower surface of the reaction furnace outer wall
10
for exhausting gas after the reaction is completed.
The principle for forming a thin film on the wafer W using the chemical vapor deposition apparatus of
FIG. 1
will be explained. Namely, a source gas or process source is flown into a vaporizer(not shown) in a fluid state for forming a thin film. The thusly flown source gas or process source is mixed with a carry gas formed of N
2
, O
2
, Ar, etc. in the vaporizer and is vaporized. Next, the vaporized process source is flown into the gas distributor
11
via the gas inlet port
12
in a gas state and reaches at the wafer via a plurality of nozzles
11
a
formed at the gas distributor
11
and is chemically reacted based on a heat energy generated by the heating apparatus
14
, so that a thin film is formed on the wafer W. At this time, if a heat environment is not proper in the interior of the gas distributor
11
, the process gases may be abnormally reacted or the vaporized gas may be liquefied, so that the thin film formed on the wafer W includes particles, whereby the quality of the film may be decreased, and it is impossible to obtain a certain deposition ratio. Therefore, in order to prevent the above-described problems, the temperature in the gas distributor is maintained at a certain degree.
The structure of the conventional gas distributor and the temperature control method will be explained.
FIG. 2B
is a cross-sectional view illustrating a conventional first type gas distributor
20
. As shown therein, the gas distributor
20
includes an upper plate
21
and a multiple-hole plate
23
having a plurality of holes or nozzles
22
. A gas inlet tube
24
is connected to a center portion of the upper plate
21
. The upper plate
21
and the multiple-hole plate
23
are engaged by a plurality of screws
26
along an edge portion. In addition, a heater
25
is installed at an edge portion of the upper plate at an angle of 90°.
FIG. 2A
is a plan view illustrating the upper surface of the first type gas distributor of FIG.
2
B. As shown therein, four heaters
25
are installed at an edge portion of the upper plate
21
, and a gas inlet tube
24
is connected to a center portion of the upper plate
24
.
FIG. 3A
is a vertical cross-sectional view illustrating a conventional second type gas distributor. As shown therein, a gas distributor
30
includes an upper plate
31
, and a multiple-hole plate
33
having a plurality of holes or nozzles
32
. A gas inlet tube
34
is connected to a center portion of the upper plate
31
, and the upper plate
31
and the multiple-hole plate
33
are engaged by a plurality of screws
36
along an edge portion. Four heaters
35
are installed at a center portion of the upper plate
31
near the gas inlet tube
34
at a certain interval. The position of the heater is different compared to the first type gas distributor. Namely, the first type heater is formed at an edge portion of the upper plate, and the second type heater is formed at a center portion of the upper plate.
FIG. 3B
is a plan view illustrating a second type gas distributor of FIG.
3
A. The same elements as
FIG. 3A
are given the same reference numerals. A gas inlet tube
34
is installed at a center of the upper plate
31
, and a heater
35
is installed around the gas inlet tube
34
.
FIG. 3C
is a plan view illustrating a multiple-hole plate
33
of the second type gas distributor of
FIG. 3A. A
plurality of nozzles
32
each having a diameter of 1~2 mm are installed at a certain distance from one another. A plurality of screw holes
36
a
are formed at an edge portion of the multiple-hole plate
33
for receiving the screws therein.
FIG. 4A
is a vertical cross-sectional view illustrating a third type gas distributor
40
. As shown therein, the third type gas distributor
40
includes an upper plate
41
, a multiple-hole plate
43
having a plurality of nozzles
42
, a gas inlet tube
44
, and a flat plate heater
45
. The upper plate
41
and the multiple-hole plate
43
are engaged by the screws
46
. The plate heater
45
is installed on the entire upper portion of the upper plate
41
. The multiple-hole plate
43
is formed in a dish shape and has a distributing function capable of distributing a certain gas to an outer portion in the chamber. The multiple-hole plate
43
includes a lower portion
43
a
and a slant portion
43
b.
FIG. 4B
is a plan view illustrating a third type gas distributor of FIG.
4
A. The same elements as
FIG. 4A
are given the same reference numerals.
FIG. 4C
illustrates a multiple-hole plate
43
. In
FIG. 4C
, the same reference numerals of
FIG. 4C
as
FIG. 4A
corre
Bueker Richard
Fleshner & Kim LLP
Hyundai Electronics Industries Co,. Ltd.
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