U.S. patent application number 13/237076 was filed with the patent office on 2013-02-07 for method for removing oxygen from aluminum nitride by carbon.
This patent application is currently assigned to Chung-Shan Institute of Science and Technology Armaments, Bureau, Ministry of National Defense. The applicant listed for this patent is Ching-Hui ChiangLin, Chia-Yi Hsiang, Yang-Kuao Kuo, Te-Po Liu. Invention is credited to Ching-Hui ChiangLin, Chia-Yi Hsiang, Yang-Kuao Kuo, Te-Po Liu.
Application Number | 20130034488 13/237076 |
Document ID | / |
Family ID | 47521690 |
Filed Date | 2013-02-07 |
United States Patent
Application |
20130034488 |
Kind Code |
A1 |
Kuo; Yang-Kuao ; et
al. |
February 7, 2013 |
METHOD FOR REMOVING OXYGEN FROM ALUMINUM NITRIDE BY CARBON
Abstract
Disclosed is a method for removing oxygen from aluminum nitride
by carbon. At first, an oven is provided. An aluminum nitride
substrate is located in the oven. Nitrogen is introduced into the
oven to form an atmosphere of nitrogen. The temperature is
increased to the transformation point of the aluminum nitride
substrate in the oven. Then, the heating is stopped and quenching
is conducted in the oven. Carbon is introduced into the oven in the
quenching. Thus, oxygen included in the aluminum nitride substrate
reacts with the carbon to produce carbon monoxide or carbon
dioxide. The carbon monoxide or carbon is released from the oven as
well as the nitrogen. Thus, the aluminum nitride substrate is
purified.
Inventors: |
Kuo; Yang-Kuao; (Taoyuan
County, TW) ; Hsiang; Chia-Yi; (Taoyuan County,
TW) ; ChiangLin; Ching-Hui; (Taoyuan County, TW)
; Liu; Te-Po; (Taoyuan County, TW) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Kuo; Yang-Kuao
Hsiang; Chia-Yi
ChiangLin; Ching-Hui
Liu; Te-Po |
Taoyuan County
Taoyuan County
Taoyuan County
Taoyuan County |
|
TW
TW
TW
TW |
|
|
Assignee: |
Chung-Shan Institute of Science and
Technology Armaments, Bureau, Ministry of National Defense
Taoyuan County
TW
|
Family ID: |
47521690 |
Appl. No.: |
13/237076 |
Filed: |
September 20, 2011 |
Current U.S.
Class: |
423/412 |
Current CPC
Class: |
C04B 41/80 20130101;
C04B 41/0072 20130101; C04B 41/009 20130101; C01B 21/0728 20130101;
C04B 2235/723 20130101; C04B 2235/664 20130101; C04B 41/53
20130101; C04B 41/0072 20130101; C04B 35/581 20130101; C04B 41/009
20130101; C04B 35/581 20130101; C04B 41/4517 20130101 |
Class at
Publication: |
423/412 |
International
Class: |
C01B 21/072 20060101
C01B021/072 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 4, 2011 |
TW |
100127699 |
Claims
1. A method for removing oxygen from aluminum nitride by carbon
including the steps of: providing an oven; providing an aluminum
nitride substrate in the oven, introducing only nitrogen into the
oven to form an atmosphere of nitrogen and increasing the
temperature to the transformation point of the aluminum nitride
substrate in the oven; and stopping the heating and starting
quenching in the oven, introducing carbon and nitrogen into the
oven only during the quenching so that oxygen included in the
aluminum nitride substrate reacts with the carbon to produce carbon
monoxide or carbon dioxide, and releasing the carbon monoxide or
carbon dioxide from the oven as well as the nitrogen, thus
purifying the aluminum nitride substrate.
2. The method for removing oxygen from aluminum nitride by carbon
according to claim 1, further including the steps of providing a
nitrogen supply unit connected to the oven and providing a carbon
supply unit connected to the oven, wherein the oven includes an
exhaust pipe formed thereon and at least one heating unit provided
therein.
3. The method for removing oxygen from aluminum nitride by carbon
according to claim 2, wherein the nitrogen supply unit is connected
to the carbon supply unit before they are connected to the
oven.
4. The method for removing oxygen from aluminum nitride by carbon
according to claim 2, further including the step of providing
valves among the oven, the nitrogen supply unit and the carbon
supply unit.
5. The method for removing oxygen from aluminum nitride by carbon
according to claim 1, wherein the nitrogen supply unit provides
nitrogen with concentration 2N to 6N.
6. The method for removing oxygen from aluminum nitride by carbon
according to claim 1, wherein the transformation point of the
aluminum nitride substrate is higher than 1500.degree. C.
7. The method for removing oxygen from aluminum nitride by carbon
according to claim 1, wherein the supply of the carbon and nitrogen
starts when the temperature drops below 1500.degree. C. Please add
the following new claim:
8. The method of claim 3, wherein the carbon is induced to flow
into the oven via flow of the nitrogen from the nitrogen supply
unit into the carbon supply unit.
Description
BACKGROUND OF INVENTION
[0001] 1. Field of Invention
[0002] The present invention relates to a method for removing
oxygen from aluminum nitride by carbon and, more particularly, to a
method for quenching an aluminum nitride substrate in an
environment of carbon and nitrogen in an oven so that the carbon
reduces oxygen contained in the oven and oxygen included in the
aluminum nitride substrate into carbon monoxide or carbon dioxide,
thus making a pure, quality aluminum nitride substrate.
[0003] 2. Related Prior Art
[0004] LED devices have become popular recently because they
operate at high efficiencies while consuming only a little
electricity and are friendly to the environment.
[0005] Currently, most LED devices are used as backlights for cell
phones. LED devices are however expected to replace conventional
lights in the future. To this end, there is still a long way to go.
There are problems related to the conversion efficiency, heat
dissipation, color rendering, life and price for example.
[0006] Regarding the heat dissipation, an LED device converts a
portion of electricity into light but converts the other portion of
the electricity into heat. The heat would increase the temperature
of the LED device excessively and therefore affect the efficiency,
life and stability of the LED device should it not be dissipated
fast.
[0007] Aluminum nitride ("AlN") is suitable for use as a heat sink
and a substrate of an LED device because it exhibits a high heat
transfer coefficient (170 W/mK), a high insulation resistivity and
an excellent mechanical strength and is refractory and
vibration-resistant. The heat transfer coefficient of an aluminum
nitride substrate is much higher than the heat transfer coefficient
(20 W/mK) of a conventional substrate made of sapphire
("Al.sub.2O.sub.3"). Hence, aluminum nitride substrates are getting
more and more attention in the field of high-power LED devices.
[0008] As the heat transfer coefficient of an aluminum nitride
substrate is 7 times higher than the heat transfer coefficient of a
sapphire substrate, the aluminum nitride substrate increase the
life of an LED device to 6,000.about.7,000 hours. The aluminum
nitride could however be oxidized on the surface easily. That is, a
thin layer of aluminum oxide could easily be formed on the surface
of the aluminum nitride substrate. The thin layer of aluminum oxide
compromises the quality and concentration of the aluminum nitride
substrate and might even affect the heat dissipation.
[0009] The present invention is therefore intended to obviate or at
least alleviate the problems encountered in prior art.
SUMMARY OF INVENTION
[0010] It is the primary objective of the present invention to
provide a method for making a pure, quality aluminum nitride
substrate.
[0011] To achieve the foregoing objective, the method includes the
step of providing an oven. An aluminum nitride substrate is
provided in the oven. Nitrogen is introduced into the oven to form
an atmosphere of nitrogen. The temperature is increased to the
transformation point of the aluminum nitride substrate in the oven.
Then, the heating is stopped and quenching is conducted in the
oven. Carbon is introduced into the oven during the quenching.
Thus, oxygen included in the aluminum nitride substrate reacts with
the carbon to produce carbon monoxide or carbon dioxide. The carbon
monoxide or carbon dioxide is released from the oven as well as the
nitrogen. Thus, the aluminum nitride substrate is purified.
[0012] In an aspect, the method further includes the steps of
providing a nitrogen supply unit connected to the oven and
providing a carbon supply unit connected to the oven. The oven
includes an exhaust pipe formed thereon and at least one heating
unit provided therein.
[0013] In another aspect, the nitrogen supply unit is connected to
the carbon supply unit before they are connected to the oven.
[0014] In another aspect, the method further includes the step of
providing valves among the oven, the nitrogen supply unit and the
carbon supply unit.
[0015] In another aspect, the nitrogen supply unit provides
nitrogen with concentration 2N to 6N.
[0016] In another aspect, the transformation point of the aluminum
nitride substrate is higher than 1500.degree. C.
[0017] In another aspect, the supply of the carbon starts when the
temperature drops below 1500.degree. C.
[0018] Other objectives, advantages and features of the present
invention will be apparent from the following description referring
to the attached drawings.
BRIEF DESCRIPTION OF DRAWINGS
[0019] The present invention will be described via detailed
illustration of the preferred embodiment referring to the drawings
wherein:
[0020] FIG. 1 is a perspective view of a system for executing a
method for removing oxygen from aluminum nitride by carbon
according to the preferred embodiment of the present invention;
[0021] FIG. 2 is a perspective view of the system at another step
than shown in FIG. 1; and
[0022] FIG. 3 is a perspective view of the system at another step
than shown in FIG. 2.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENT
[0023] Referring to FIGS. 1 through 3, there is shown a system for
executing a method for removing oxygen from aluminum nitride by
carbon according to the preferred embodiment of the present
invention. The method includes three steps shown in FIGS. 1 through
3, respectively.
[0024] Referring to FIG. 1, the system includes an oven 1, a
nitrogen supply unit 12 and a carbon supply unit 13. The oven 1
includes an exhaust pipe 11 formed thereon and two heating units 15
provided therein. The oven 1 is connected to both of the nitrogen
supply unit 12 and the carbon supply unit 13. The nitrogen supply
unit 12 is connected to the carbon supply unit 13 before they are
connected to the oven 1. There are several valves 14 provided among
the oven 1, the nitrogen supply unit 12 and the carbon supply unit
13. Each of the valves 14 is operable to open and close the
nitrogen supply unit 12 and the carbon supply unit 13.
[0025] Referring to FIG. 2, an aluminum nitride substrate 2 is
provided in the oven 1. One of the valves 14 is operable to allow
nitrogen to travel into the oven 1 from the nitrogen supply unit 12
to produce a nitrogen atmosphere in the oven 1. The heating units
15 are turned on to increase the temperature to the transformation
point of the aluminum nitride substrate 2 in the oven 1. The
transformation point of the aluminum nitride substrate 2 is higher
than 1500.degree. C. The higher the concentration of the nitrogen
in the nitrogen supply unit 12, the better. The concentration of
the nitrogen in the nitrogen supply unit 12 is preferably 2N to
6N.
[0026] Referring to FIG. 3, the heating unit 15 of the oven 1 is
turned off for quenching. During the quenching, another one of the
valves 14 is operable to allow carbon to travel into the oven 1
from the carbon supply unit 13. Oxygen contained in the oven 1 and
oxygen included in the aluminum nitride substrate 2 react with the
carbon to produce carbon monoxide or carbon dioxide. The carbon
monoxide or carbon dioxide is later released from the oven 1
through the exhaust pipe 11 together with the nitrogen. The carbon
supply unit 13 is closed when the temperature drops below
1500.degree. C. in the oven 1. Thus, a pure aluminum nitride
substrate 2 is made.
[0027] As described above, the quenching is conducted in the
atmosphere of the carbon and the nitrogen, the carbon reduces the
oxygen into the carbon monoxide or carbon dioxide to avoid a thin
layer of aluminum oxide on the surface of the aluminum nitride
substrate 2. Thus, a pure, quality aluminum nitride substrate 2 is
made.
[0028] The present invention has been described via the detailed
illustration of the preferred embodiment. Those skilled in the art
can derive variations from the preferred embodiment without
departing from the scope of the present invention. Therefore, the
preferred embodiment shall not limit the scope of the present
invention defined in the claims.
* * * * *