Coating apparatus – Gas or vapor deposition – With treating means
Reexamination Certificate
1999-03-31
2002-05-21
Mills, Gregory (Department: 1763)
Coating apparatus
Gas or vapor deposition
With treating means
C118S719000, C118S715000, C156S345420, C438S706000
Reexamination Certificate
active
06391116
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a semiconductor device manufacturing apparatus and a semiconductor device manufacturing method, and particularly to a diffusion furnace used in a diffusion process and an oxide film forming method using the diffusion furnace.
2. Description of the Related Art
A conventional diffusion furnace and an oxide film forming method using the diffusion furnace will be described.
FIG. 1
is a longitudinal-sectional view showing a vertical type diffusion furnace to describe a conventional technique, and
FIG. 2
is a diagram showing an oxidation treatment sequence of the conventional diffusion furnace. The vertical type diffusion furnace shown in
FIG. 1
includes a furnace tube
2
to which a process gas introducing pipe
5
and a gas discharging pipe
6
are secured, a wafer support boat
3
for mounting wafers
4
thereon, and a heater
1
for keeping the inside of the furnace tube
2
to a desired temperature.
Referring to
FIGS. 1 and 2
, steps until the oxidation treatment carried out in the vertical type diffusion furnace will be described.
First, wafers
4
are introduced into the furnace tube
2
(first step). At this time, oxygen gas of 2 [SLM] diluted with nitrogen gas of 18 [SLM] is introduced as process gas into the furnace tube
2
, and the inside of the furnace tube
2
is kept at 800° C. by a heater
1
, for example.
Subsequently, temperature stabilization (Recovery) in the furnace tube
2
after the wafers
4
are introduced is promoted (second step), and then the temperature increase to an oxidation treatment temperature, for example, 850° C. (Ramp-up) (third step) and the temperature stabilization after the increase of the temperature (Ramp Recovery) (fourth step) are carried out. Here, the gas conditions from the second step to the fourth step are the same as the first step.
In a fifth step, steam gas of 15 [SLM] is supplied as process gas to perform oxidation treatment (Burning), thereby obtaining the final oxide film thickness.
The thickness of the oxide film which has been formed until the time just before the fifth step (oxidation treatment step) is equal to 3.5 nm on the average, and the in-batch film thickness uniformity is equal to 5%. Further, the thickness of the oxide film which has been formed until the time just after the first step is completed is equal to 2.5 nm on the average. The in-batch film thickness uniformity is equal to 8%.
Here, the in-batch film thickness uniformity is defined as a value calculated according to the following equation:
“in-batch film thickness uniformity”=(in-batch maximum difference of film thickness average values of respective wafers)×100/(2×the in-batch average value of film thickness average values of respective wafers)
Further, the film thickness average value of each wafer represents the average value of film thickness values at five points on the wafer surface (the center point of the wafer and four peripheral points which are located on a cross passing the wafer center point and spaced from the wafer edge by 5 mm).
The thickness of the oxide film formed on the wafer
4
before the oxidation treatment step is determined by the exposure time for which the wafers
4
are exposed to oxygen atmosphere in the furnace tube
2
, the oxygen concentration in the furnace tube
2
, the temperature in the furnace tube
2
, etc.
Here, with respect to the conventional diffusion furnace, since oxygen atmospheric layer has been formed entirely in the furnace tube
2
when the wafers
4
are introduced into the furnace tube
2
, wafers located at the top and bottom sides of the wafer support boat
3
are exposed to oxygen atmosphere for different times, respectively (that is, the exposure time is different between the wafer located at the top side and the wafer located at the bottom side). Accordingly, the thickness of the oxide film formed before the oxidation treatment step is larger at the top side than at the bottom side, so that the in-batch film thickness uniformity is lowered.
SUMMARY OF THE INVENTION
The present invention has been implemented in view of the foregoing problem, and has an object to a semiconductor device manufacturing apparatus and a semiconductor device manufacturing method which can form an oxide film uniformly in a batch of wafer when the oxide film is formed on a wafer mounted in each part of a wafer support boat which is inserted in a furnace tube.
In order to attain the above object, according to a semiconductor device manufacturing apparatus of the present invention, a furnace tube port gas introducing pipe (port) for supplying desired gas is provided at only one end of the furnace tube, and when a treating target of semiconductor wafer such as silicon wafer is put into the furnace tube, an atmospheric layer of one or more kinds of desired gas is formed only at the port of the furnace tube by the desired reactive gas such as oxidative gas supplied from the furnace tube port gas introducing pipe. More specifically, the semiconductor device manufacturing apparatus of the present invention has the following feature.
According to one aspect of the present invention, a member to be treated or treating target is inserted into the furnace tube from one end of the furnace tube, and when the member to be treated is inserted, gas containing at least reactive gas is introduced into the furnace tube from a gas introducing port disposed near to the one end of the furnace tube to thereby supply the gas to the member to be treated while gas containing at least non-reactive gas is supplied into the furnace tube from another gas introducing port.
Further, according to the present invention, in a semiconductor device manufacturing method using a semiconductor device manufacturing apparatus in which a batch of plural semiconductor substrates serving as treatment targets are inserted into a furnace tube to perform the treatment such as oxidation on the substrates, in a process of inserting the batch of the plural semiconductor substrates serving as the treatment targets from an insertion port at one end of the furnace tube into the furnace tube, gas containing at least reactive gas is introduced into the furnace tube through a gas introducing port disposed near to the one end of the furnace tube in the direction substantially perpendicular to the batch insertion direction, thereby forming a gas atmosphere having a layer boundary in the direction substantially perpendicular to the batch insertion direction, and gas containing at least non-reactive gas is introduced through another gas introducing port of the furnace tube at the opposite end to the one end of the furnace tube, thereby making uniform in thickness the films formed on the plural substrates serving as the treatment targets under the gas atmosphere in the batch.
The present invention provides a semiconductor device manufacturing apparatus for performing a surface treatment of a semiconductor substrate, comprising:
a furnace tube having a port at one end thereof;
a heating means for the furnace tube;
a semiconductor substrate support means for inserting the semiconductor substrate into the furnace tube through the port of the furnace tube;
a first gas introducing port for introducing a reactive gas for the surface treatment into a first area of the inside of the furnace tube near to the port of the furnace tube; and
a second gas introducing port for introducing a non-reactive gas to the semiconductor substrate into a second area of the inside of the furnace tube at the other end side of the furnace tube, wherein the semiconductor substrate is moved to the second area by means of the semiconductor substrate support means.
The first gas introducing port may be disposed at a lateral surface of the furnace tube. The semiconductor substrate support means may support the semiconductor substrate perpendicularly to the insertion direction of the semiconductor substrate.
The first gas introducing port may have a first portion for introducing
Hassanzadeh P.
Mills Gregory
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