Semiconductor device manufacturing: process – Making device or circuit emissive of nonelectrical signal – Compound semiconductor
Reexamination Certificate
1997-04-15
2001-07-10
Wilczewski, Mary (Department: 2822)
Semiconductor device manufacturing: process
Making device or circuit emissive of nonelectrical signal
Compound semiconductor
C438S047000, C438S505000, C438S508000, C438S509000, C438S930000
Reexamination Certificate
active
06258617
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a blue light emitting element employing a gallium-nitride-based compound semiconductor and a method of manufacturing the same.
BACKGROUND ART
Gallium-nitride-based compound semiconductor such as GaN, InGaN, and GaAlN is drawing attention as material for fabricating blue light emitting diodes (LEDs) and blue laser diodes (LDs) . This kind of compound semiconductor is capable. of emitting blue light of sufficient intensity hardly realized so far.
A blue light emitting element employing the gallium-nitride-based compound semiconductor is disclosed in, for example, Japanese Unexamined Patent Publication No. 4-321280.
FIG. 7
shows the basic structure of a blue light emitting element
2
according to a prior art. On a sapphire substrate
200
, a buffer layer
201
is formed. On the buffer layer
201
, an n-type GaN semiconductor layer
202
and a p-type GaN semiconductor layer
203
are formed. Between the layers
202
and
203
, there is a depletion layer to which carriers are injected to emit light.
The blue light emitting element is manufactured by growing crystals on a sapphire substrate according to a CVD method and by forming gallium nitride semiconductor layers on the substrate. The substrate is properly cut into chips. Each chip is connected to a wire frame, and wiring is made to complete a device.
A natural cooling process in an inert gas is disclosed in Japanese Unexamined Patent Publication No. 8-125222. To replace an atmospheric gas at room temperature with an inert gas, the disclosure vacuums a reactive tube under a high temperature. This high temperature may grow a substrate. When vacuuming the reactive tube, the grown crystals may evaporate. As a result, no grown crystals may be left, or the crystallized film may be thinned.
In the gallium-nitride-based blue light emitting element of the prior art, impurities in the semiconductor layers are not sufficiently activated. Accordingly, the prior art needs an after-treatment of thermal annealing.
The thermal annealing increases the number of processes and processing time. Since the gallium nitride semiconductor is exposed to a high temperature of 600° C. or over for a long time, nitrogen may escape from crystals and deteriorate surface homology. This results in changing semiconductor properties and deteriorating blue light emitting efficiency and yield.
DISCLOSURE OF INVENTION
An object of the present invention is to provide a gallium-nitride-based blue light emitting element involving a small number of manufacturing processes and a method of manufacturing the same.
Another object of the present invention is to provide a gallium-nitride-based blue light emitting element realizing high yield and a method of manufacturing the same.
Still another object of the present invention is to provide a gallium-nitride-based blue light emitting element proper for mass-production and a method of manufacturing the same.
Still another object of the present invention is to provide a gallium-nitride-based blue light emitting element realizing high-intensity light and low power consumption and a method of manufacturing the same.
In order to accomplish the objects, the present invention provides a blue light emitting element consisting of a first gallium-nitride-based semiconductor layer containing impurities of a first conductivity type, a gallium-nitride-based semiconductor active layer that is substantially intrinsic, and a second gallium-nitride-based semiconductor layer containing impurities of a second conductivity type that is opposite to the first conductivity type. The first and second gallium-nitride-based semiconductor layers and gallium-nitride-based semiconductor active layer are formed according to a thermal CVD method and are left in an inert gas to cool by themselves, so that seven percent or more of the impurities are activated.
The present invention also provides a method of manufacturing a blue light emitting element including the steps of forming, according to a thermal CVD method in a vacuum chamber, a first gallium-nitride-based semiconductor layer containing impurities of a first conductivity type, a gallium-nitride-based semiconductor active layer that is substantially intrinsic, and a second gallium-nitride-based semiconductor layer containing impurities of a second conductivity type that is opposite to the first conductivity type, and leaving the layers in an inert gas so that the layers may cool by themselves.
The present invention involves simple processes without thermal annealing and improves yield. The gallium-nitride-based compound semiconductor blue light emitting element of the present invention realizes high-intensity light with small power consumption.
REFERENCES:
patent: 5432808 (1995-07-01), Hatano
patent: 5583879 (1996-12-01), Yamazaki
patent: 5729029 (1998-03-01), Rudaz
patent: 5733796 (1998-03-01), Manabe et al.
patent: 5742628 (1998-04-01), Fujii
patent: 5747832 (1998-05-01), Nakamura et al.
patent: 5751013 (1998-05-01), Kidoguchi et al.
patent: 5751021 (1998-05-01), Teraguchi
patent: 5753939 (1998-05-01), Sassa et al.
patent: 5804834 (1998-09-01), Shimoyama et al.
patent: 6-196755 (1994-07-01), None
patent: 6-232451 (1994-08-01), None
patent: 8-8460 (1996-01-01), None
patent: 8-32113 (1996-02-01), None
patent: 8-125222 (1996-05-01), None
patent: 8-115880 (1996-05-01), None
Fujimoto Hidetoshi
Ishikawa Masayuki
Nitta Koichi
Foley & Lardner
Kabushiki Kaisha Toshiba
Wilczewski Mary
LandOfFree
Method of manufacturing blue light emitting element does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method of manufacturing blue light emitting element, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method of manufacturing blue light emitting element will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2466311