Combustion – Flame holder having protective flame enclosing or flame...
Reexamination Certificate
2000-10-11
2001-08-21
Yeung, James C. (Department: 3743)
Combustion
Flame holder having protective flame enclosing or flame...
C431S119000, C431S354000
Reexamination Certificate
active
06276926
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATION
This application claims the priority benefit of Taiwan application serial no. 89119320, filed Sep. 20, 2000.
BACKGROUND OF THE INVENTION
1. Field of Invention
The present invention relates to the gas injector of a thermal oxidation station. More particularly, the present invention relates to an injector for water free of external torch.
2. Description of Related Art
Thermal oxidation can be roughly divided into dry oxidation and wet oxidation. In dry oxidation, oxygen together with suitable amount of inert gases or nitrogen gas is passed into a heated furnace (at a temperature of around 900° C.) to initiate the formation of an oxide layer on a silicon wafer. In wet oxidation, rather than passing water vapor directly into a reaction chamber, water formed by reacting gaseous hydrogen with oxygen (at an elevated temperature above 600° C.) is passed into reaction chamber to carry out the oxidation. Since the water vapor formed by reacting hydrogen and oxygen is much purer and cleaner than distilled water, the silicon dioxide (SiO
2
) layer formed by wet oxidation has good electrical properties.
In general, the reaction between hydrogen and oxygen is carried out at high temperature inside a gas injector. A gas injector can further be distinguished by internal torch or external torch. At present, most oxidation furnace has external torch gas injector. The external torch injector comprises of a hydrogen-oxygen torch chamber and a gas injector. When gaseous hydrogen and gaseous oxygen reacts inside the torch chamber to form water moisture, the moisture is channeled into a quartz oxidation tube via a connection pipe.
FIG. 1
is a sketch showing a conventional external torch gas injector. As shown in
FIG. 1
, a conventional external torch gas injector
100
includes an outer tube
102
and an inner tube
104
. The inner tube
104
is enclosed within the outer tube
102
. The outer tube
102
has a side tube
102
a
and separate inner tube emission holes
102
c
,
102
d
and
102
e
. The outer wall of the outer tube
102
is joined to a ball-and-socket joint
108
. There is an opening at the back end of the outer tube
102
for inserting a thermocouple
110
. The inner tube
104
has a side tube
104
a
and an inner tube emission hole
104
c
. The side tube
102
a
further has an outer tube inlet
102
b
end the side tube
104
a
has an inner tube inlet
104
b
. The side tube
102
a
is roughly perpendicular to the outer tube
102
while the side tube
104
a
is roughly perpendicular to the inner tube
104
.
To carry out wet oxidation, a quartz external torch gas injector
100
is used. Gaseous hydrogen (H
2
) is delivered to the inner tube inlet
104
b
while oxygen (O
2
) is passed through the outer tube inlet
102
b
into the hydrogen-oxygen torch chamber
112
. Oxygen passes from the outer tube inlet
102
b
via three different outer tube emission holes
102
c
,
102
d
and
102
e
into the hydrogen-oxygen torch chamber
112
. Hydrogen enters from the inner tube opening
104
b
and passes through the inner tube emission hole
104
c
before delivering into the hydrogen-oxygen torch chamber. Alternatively, the hydrogen can also pass through the inner tube inlet
104
b
into the hydrogen-oxygen torch chamber
112
. During wet oxidation reaction, flow rate of oxygen into the hydrogen-oxygen torch chamber
112
must be greater than one half times that of hydrogen. In other word, the mole ratio between hydrogen and oxygen is about 1:1/2 or more to prevent hydrogen accumulation inside the chamber
112
. When the concentration of hydrogen and oxygen reaches a suitable level and the temperature rises to a set level, hydrogen and oxygen will automatically ignite according to the reaction formula (a) below:
H
2
(
g
)
+
1
2
O
2
(
g
)
→
Δ
H
2
O
(
g
)
(
a
)
Water vapor created according to formula (a) will pass out through a connection pipeline into the oxidation chamber for wet oxidation.
After the torching reaction between hydrogen and oxygen has been continued for some time, large number of water droplets
114
may accumulate near the ball-and-socket joint
108
because the temperature there is only about 60° C. These accumulated water droplets
114
may affect subsequent dry oxidation operation leading to non-uniform oxide thickness.
SUMMARY OF THE INVENTION
Accordingly, one object of the present invention is to provide an injector for water free of external torch capable of preventing water vapor produced by hydrogen-oxygen burning from condensing in the cooler part of the injector.
To achieve these and other advantages and in accordance with the purpose of the invention, as embodied and broadly described herein, the invention provides an injector for water free of external torch. The injector includes an outer tube, a first inner tube and a second inner tube. The outer tube has a side tube and a plurality of outer tube emission holes. The outer wall of the outer tube joins with a ball-and-socket joint. The outer tube emission holes are at the front end of the outer tube. The side tube of the outer tube further includes an outer tube inlet. The outer tube inlet is used for channeling in a first gas. The plurality of outer tube emission holes is used for exhausting the first gas. The first inner tube is enclosed inside the outer tube. The first inner tube has a side tube and a first inner tube emission hole. The first inner tube emission hole is also at the front end of the outer tube. The side tube of the first inner tube further includes a first inner tube inlet. The first inner tube inlet is used for channeling in a second gas while the first inner tube emission hole is used for exhausting the second gas. The second inner tube is also enclosed inside the outer tube. The second inner tube has a second inner tube inlet and a second inner tube emission hole. The second inner tube inlet is at the back end of the outer tube. The second inner tube emission hole is on the tube wall of the outer tube, close to the largest cross-section in the ball-and-socket joint. The second inner tube inlet is used for channeling in a third gas. The second inner tube emission hole is used for exhausting the third gas. In an alternative design, besides using a second outer tube emission hole to replace the second inner tube, everything is similar. The distance from the largest cross-section of the ball-and-socket joint to the junction of the ball-and-socket joint is d. The second outer tube emission holes are positioned on the outer wall of the outer tube at a distance −d from the largest cross-section of the ball-and-socket joint. Furthermore, the direction of a sprout on the second outer tube emission holes is tilted at a specified angle relative to the ball-and-socket junction.
It is to be understood that both the foregoing general description and the following detailed description are exemplary, and are intended to provide further explanation of the invention as claimed.
REFERENCES:
patent: 3364967 (1968-01-01), Solak
patent: 4664619 (1987-05-01), Johnson et al.
patent: 4773848 (1988-09-01), Jalbert
patent: 5085576 (1992-02-01), Boone et al.
Chen Tony
Huang I-Ho
Thomas, Kayden, Horstmeyer & Risley LLP
United Microelectronics Corp.
Yeung James C.
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