Semiconductor device manufacturing: process – Formation of semiconductive active region on any substrate – On insulating substrate or layer
Reexamination Certificate
2002-01-30
2004-04-27
Mulpuri, Savitri (Department: 2812)
Semiconductor device manufacturing: process
Formation of semiconductive active region on any substrate
On insulating substrate or layer
C438S483000
Reexamination Certificate
active
06727164
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a method for fabricating a semiconducting nitride film, a susceptor and an apparatus for fabricating a semiconducting nitride film which are preferably usable for semiconductor films to construct semiconductor devices or optoelectronic devices such as light-emitting diodes and high velocity IC chips.
2. Related Art Statement
Group III nitride films including elemental Al are employed as semiconductor films constituting light-emitting diodes, and recently, win a lot of attention as semiconductor films constituting high velocity IC chips to be used in cellular phones.
Such Group III nitride films are usually fabricated by MOCVD methods using Al raw material including trimethylaluminum (TMA) or triethylaluminum (TEA) as gas and nitrogen raw material gas such as ammonia.
In this case, a substrate on which a Group III nitride film is formed is set on a susceptor tray installed in a given reactor and then heated to 1000° C. or over by a heater built in the susceptor tray or provided outside the susceptor tray. Thereafter, Al raw material gas and nitrogen raw material gas are supplied with a carrier gas onto the substrate.
Through thermochemical reactions, the raw materials are resolved into their components, which are chemically reacted, to deposit and fabricate a desired Group III nitride film on the substrate.
FIGS. 1 and 2
are a perspective view and a cross sectional view showing the arrangement of a substrate on a susceptor tray, respectively, when a semiconducting nitride film is fabricated on the substrate by a MOCVD method.
As shown in
FIGS. 1 and 2
, a given recessed portion
15
is formed at the center of a susceptor tray
10
, and a substrate
20
is set in the recessed portion
15
. Since the size of the susceptor tray
10
is much larger than that of the substrate
20
, the substrate
20
can be heated uniformly. After a given semiconducting nitride film is fabricated, the substrate
20
is released from the susceptor tray
10
, and post-processed.
In the practical manufacturing process of semiconducting nitride films, the susceptor tray
10
is fixed in a reactor of a MOCVD apparatus, and a plurality of substrates
20
are set into the recessed portion
15
continuously in turn. Then, semiconducting nitride films are fabricated on the substrates
20
, and the substrates
20
are released from the susceptor tray
10
in turn. Therefore, during a given operation period, debris of the semiconducting nitride films, which has a similar composition to the one of the film, may be deposited on the outer surface
10
A of the susceptor tray
10
.
If a large amount of debris is created, the step between the substrate
20
and the susceptor tray
10
is changed, so that the flow condition of the raw material gases is changed. As a result, the fabricating condition is affected slightly, the properties of the resulting semiconducting nitride films are deteriorated.
If the debris contains many Ga elements, it can be etched and removed when the susceptor tray
10
is disposed in a hydrogen flow. However, if a plurality of semiconducting nitride films including many Al elements are fabricated, and thus the debris contains many Al elements, the debris can not be etched and removed in such a hydrogen flow.
During a long operation time, the properties of the resulting semiconducting nitride films including many Al elements are slightly changed, and thus, cannot be made stable.
When the fabricating step of forming the semiconducting nitride film is performed under a depressurized atmosphere, heat can not be transmitted to the substrate
20
from the susceptor tray
10
, and thus, the temperature of the outer surface
10
A of the susceptor tray
10
is higher than the surface temperature of the substrate
20
, so that the above-mentioned raw material gases are thermochemically reacted in a gas phase and deposited on the outer surface
10
A. As a result, the fabricating efficiency and the property of the semiconducting nitride film is deteriorated due to the intense reaction of the raw material gases at the outer surface
10
A.
SUMMARY OF THE INVENTION
It is an object of the present invention to repress deterioration of the properties of the semiconducting nitride film due to the debris created on a susceptor tray during fabrication of semiconducting nitride film.
In order to achieve the above object, this invention relates to a method for fabricating a semiconducting nitride film, comprising the steps of:
preparing a susceptor tray constructed of a base plate and an outer member,
setting a substrate in the recessed portion formed by disposing the outer member on the base plate, and
fabricating a semiconducting nitride film on the substrate.
In the fabricating method of the present invention, a substrate is set on the base plate of a susceptor tray so as to be surrounded by the outer member of the susceptor tray which is separately provided from the base plate. Therefore, the substrate can be heated uniformly by a heater built in or provided outside the susceptor tray, and a given semiconducting nitride film is fabricated on the substrate as usual.
In this case, the debris of the semiconducting nitride film is deposited on the outer member of the susceptor tray. However, since the outer member is detachable for the base plate of the susceptor tray, if the debris is deposited to some degree, only the outer member is taken out and washed, to remove the deposited debris easily.
If the outer member is made of a material of low optical absorption coefficient, that is, an optically transparent material of high transmissivity, the heating of the outer member due to radiation is inhibited, and thus, the reaction of raw material gases on the outer member, which results in the deterioration in the property of semiconducting nitride film, can be inhibited.
Also, since the outer member is exchangeable, a new outer member can be substituted for an old one, so that semiconducting nitride films can be made stable without washing.
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patent: 5851299 (1998-12-01), Cheng et al.
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patent: 6521292 (2003-02-01), Yudovsky et al.
patent: 2002/0028343 (2002-03-01), Shibata et al.
patent: 2-38728 (1990-03-01), None
patent: 9-266240 (1997-10-01), None
patent: 10-284425 (1998-10-01), None
patent: 2001015443 (2001-01-01), None
Asai Keiichiro
Nakamura Yukinori
Shibata Tomohiko
Tanaka Mitsuhiro
Burr & Brown
Mulpuri Savitri
NGK Insulators Ltd.
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