Closed type semiconductor wet thermal oxidation apparatus

Details Closed type semiconductor wet thermal oxidation apparatus Closed type semiconductor wet thermal oxidation apparatus

1999-10-06

2001-08-07

Bueker, Richard (Department: 1763)

Coating apparatus

Gas or vapor deposition

Crucible or evaporator structure

Reexamination Certificate

active

06270583

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an apparatus for wet thermal oxidation of a semiconductor specimen, used in a compound semiconductor fabrication process.
2. Description of the Related Art
Various systems and apparatuses for oxidizing a specimen in a compound semiconductor fabrication process have been suggested. A typical oxidation apparatus is shown in
FIG. 1
, which uses an open-type oxidation system in which external gas continuously flows in.
That is, referring to the drawing, the open-type system oxidation apparatus includes a tank
10
containing water, a heating furnace installed encompassing the tank
10
to heat the water in the tank
10
, a pipe
12
through which vapor generated by heating the water in the tank
10
flows, a chamber
14
where a specimen
100
is located, a holder
15
installed at the chamber
14
for supporting the specimen
100
, and a discharge pipe
17
through which the vapor is discharged. Also, valves
18
are installed at the pipe
12
, if necessary. A heating furnace
16
for heating the chamber
14
is installed adjacent to the chamber
14
.
In the present apparatus, nitrogen N
2
is used as a carrier gas to carry the vapor generated in the tank
10
. The nitrogen flows in the pipe
12
and the amount of flow is appropriately controlled by a flow controller
13
.
In the operation of the conventional oxidation apparatus having the above structure, first, the heating furnaces
11
and
16
are driven to heat the tank
10
containing water and the chamber
14
where the specimen
100
subject to oxidation is placed. Here, the tank
10
is heated to a temperature between 80° C. and 100° C. to generate vapor and the chamber
14
is heated to a temperature between 350° C. and 500° C. When the tank
10
and the chamber
14
are heated to appropriate temperatures, the specimen
100
supported by a holder
15
is placed in the chamber
14
.
Next, as the amount of nitrogen flowing in is controlled by the flow controller
13
, the nitrogen flows in the chamber
14
along with the vapor generated in the tank
10
and flows through the pipe
12
so that oxidation of the specimen
100
begins.
As the external nitrogen and vapor continuously flows in the chamber
14
in the oxidation apparatus adopting the open-type system, the oxidation atmosphere in the chamber
14
is barely maintained in a constant state due to change in the external circumstances. Also, when the nitrogen gas is horizontally provided with respect to the specimen
100
, as the nitrogen gas is gradually heated while proceeding due to the high temperature in the chamber
14
, the temperature of the nitrogen gas located at the position far away from an end portion of the pipe
12
through which the nitrogen gas is provided is higher than that of the nitrogen gas near the end portion of the pipe
12
. The unevenness of the temperature of the nitrogen gas consequently serves as a hindrance to uniform oxidation throughout the specimen
100
. Such tendency becomes severe as the length of the specimen
100
increases. Thus, uniformity at oxidation is lowered.
Further, vapor is condensed at an inner wall of the pipe
12
where the vapor flows and water drops are formed. The water drops are expelled into the chamber
14
by a gas such as nitrogen so that the specimen
100
may be wet, which lowers reliability and representation of a compound semiconductor specimen.
The above problem also occurs when the pipe
12
is installed perpendicular to the specimen
100
in the chamber
14
. Thus, the specimen wetting phenomenon due to water drops occurs more frequently.
SUMMARY OF THE INVENTION
To solve the above problem, it is an objective of the present invention to provide a closed type semiconductor wet thermal oxidation apparatus adopting a closed type system to be capable of isolating the system of the oxidation apparatus from external circumstances so that reliability and reproduction of an oxidation process can be secured.
Accordingly, to achieve the above objective, there is provided a compound semiconductor wet thermal oxidation apparatus which comprises a chamber unit including an inside tube containing water and supporting a specimen and an outside tube encompassing the inside tube forming a seal, and a heating unit including a furnace for heating the specimen and the water.
It is preferred in the present invention that the chamber unit comprises an installation base where the inside tube is supported and the outside tube is detachably installed, and a support base detachably coupled to the installation base forming a seal and installed to be capable of moving up and down with respect to the heating unit.


REFERENCES:
patent: 4315479 (1982-02-01), Toole et al.
patent: 5458685 (1995-10-01), Hasebe et al.

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