Coating apparatus – With means to apply electrical and/or radiant energy to work... – With means to orient coating particles
Reexamination Certificate
1999-01-18
2001-04-10
Mills, Gregory (Department: 1763)
Coating apparatus
With means to apply electrical and/or radiant energy to work...
With means to orient coating particles
C118S715000
Reexamination Certificate
active
06214116
ABSTRACT:
FIELD OF THE INVENTION
The present invention is related to a reactor for processing semiconductors, and in particular to a horizontal reactor for GaN based semiconductors.
BACKGROUND OF THE INVENTION
Compound semiconductor products have been used in emitting diodes for displays, optical telecommunications equipment, laser diodes (LD) for compact/video discs (CD/VD), photoconductors, capacitors for high speed computers, capacitors for satellites, and the like. The use of compound semiconductor products is being extendeded to mobile telecommunications equipment, blue laser diodes for optical digital displays (ODD), capacitors for optical computers, and the like.
Light emitting diodes (LED) used for color image, graphic display elements provide a full color display through a combination of the three basic colors, red, green and blue. Among these, blue LED is manufactured from III-V nitrides, AIN, GaN, InN, and the like, and have emitting wavelengths of about 450 nm. (Al
x
Ga
1- x
)
1- y
In
y
N has a direct energy band structure in the range of (1≧x ≧0) and (1≧y≧0), and has the advantage of adjusting the band gap from 2.0 eV up to 6.2 eV (wavelength range, 370-650 nm) with the variations in x and y variables providing the ability to realize various colors with a single material.
Metal Organic Chemical Vapor Deposition (MOCVD) systems are generally used in processing III nitride materials. MOCVD systems are divided into two basic groups by the arrangement of the reactor types, horizontal reactors and vertical reactors.
Vertical reactors are generally equipped with a rotating mechanism for susceptors and are inferior in terms of uniformity in epitaxial growth due to a speedy flow of source gases on the periphery of the substrate. In contrast, horizontal reactors are advantageous for obtaining uniformity due to laminar flow formation of source gases parallel with the substrate. In spite of this, conventional horizontal reactors are still weak in suppressing thermal convection resulting in limitations on the formation of a uniform epitaxial growth. Although horizontal reactors employing rotating suceptors for improving uniformity are known, they have the disadvantage of producing dust from gear friction and insufficient prevention of thermal convection even with the employment of such rotating mechanisms.
Prior art publications for GaN based semiconductor processing techniques include T. Nakamori, Nikkei Electronics Asia, 6(1), 57(1997); M. Kamp, Compound Semiconductor, 2(5), 22 (1996); I. Bhat, Compound Semiconductor, 2(5), 24(1996); S. Nakamura, Microelectronics, J., 25(8), 651 1994); and S. Strite and H. Morkoc, J. Vac. Sci. Technol., R10(4), 1237(1992).
SUMMARY OF THE INVENTION
An object of the invention is to provide an improved horizontal reactor for GaN based semiconductors which provide a solution to the above-stated problems in the art, and which achieve uniform epitaxial growth.
The above and other objects are accomplished by providing a horizontal reactor for compound semiconductor growth which comprises a susceptor adapted to hold a substrate on which a thin film for a semi-conductor grows, and an inner cell having an upper wall, a base wall and side walls. The upper wall, base wall and side walls define a reactant gas passage having two open ends. The upper wall has an inclined portion deriving laminar flow for reactant gases in the mid section of the upper wall. The lower wall supports the susceptor in a position opposite to the inclined portion. The reactor further comprises an outer cell surrronding the inner cell, an ammonia supply means for supplying ammonia gas to the reactant gas passage, a reactant gas supply means communicating with a first end of the two ends of the reactant gas passage which supplies reactant gases except ammonia gas to the reactant gas passage, a reactant gas vent means communicating with the second end of the two ends of the reactant gas passage for exhausting reactant gases out of the reactant gas passage, an ammonia gas heating means for heating ammonia gas, and a susceptor heating means for heating the susceptor.
Preferably, the reactor further comnprises a susceptor rotating means for rotating the susceptor.
Preferably, the ammonia heating means and the susceptor heating means are RF (radio frequency) coil heaters. The susceptor has a rotating portion which holds the substrate and is rotated by the susceptor rotating means and a stationary portion which surrounds the rotating portion. The ammonia supply means has an ammonia supply tube, one end of which is open at a position adjacent the rotating portion of the susceptor. The ammonia supply tube is installed through the stationary portion of the susceptor so that it is heated as the stationary portion is heated.
Preferably, a long groove extends around the substrate on an upper surface of the stationary portion of the susceptor. The end of the ammonia supply tube is connected to the groove.
Preferably, the susceptor rotating means comprises a ferrofluidic power transmission which connects the susceptor to a susceptor driving motor.
Preferably, the ammonia supply means has an ammonia supply tube, one end of which is open at a position of the base wall of the inner cell adjacent the susceptor. The ammonia heating means comprises an electric resistance heater which surrounds the ammonia supply tube and the susceptor heating means comprises an electric resistance heater positioned below the susceptor.
Preferably, the inner cell has a tube-type injector which projects downwardly from the base wall of the inner cell and receives the ammonia supply tube. The tube-type injector has a long groove which extends perpendicular to the longitudinal axis of the inner cell at the portion of the injector at which the injector meets with the base wall of the inner cell.
Preferably, the reactor further comprises a first gas supply means and a second gas supply means which supply gas to the susceptor. The susceptor has a susceptor block supported on the base wall of the inner cell, a central cylindrical portion and a rotating portion. The susceptor block is provided with a recess for receiving the rotating portion and the central cylindrical portion, a first gas supply tube through which flows the gas supplied from the first gas supply means, a second gas supply tube through which flows the gas supplied from the second gas supply means, and outlets for exhausting the gases. The central cylindrical portion is in the shape of a hollow cylinder having an open end fixed to the bottom of the recess, and is provided with a plurality of through holes. The rotating portion has a main body for holding the substrate and a hollow cylindrical portion extending downwards from the lower surface of the main body. The hollow cylindrical portion has a plurality of wings arranged on its outer periphery. The first gas supply tube is connected to the bottom of the recess so that gas supplied through the first gas supply tube fills the space defined by the bottom of the recess and the inside of the central cylindrical portion and flows into a gap between the central cylindrical portion and the hollow cylindrical portion of the rotating portion through the plurality of through holes so that the gas flow exerts a pressure against the surface of the hollow cylindrical portion to lift the rotating portion. The second gas supply tube is connected to the wall of the recess so that gas supplied through the second gas supply tube flows into a space between the hollow cylindrical portion of the rotating portion and the recess of the susceptor block so that the gas impacts against the wings to rotate the rotating portion.
The horizontal reactor of the present invention can achieve high quality epitaxial growth for the following reasons:
(1) No dust is produced by friction among gears because the present suceptor is rotated by a ferrofluidic power transmission or gas flow.
(2) Elements from thermal decomposition of ammonia gas are provided separately and yield nitrogen ions at a temperature of approximately 1,000° C. and the d
Alejandro Luz
Baker & Botts L.L.P.
Hanvac Corporation
Mills Gregory
LandOfFree
Horizontal reactor for compound semiconductor growth does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Horizontal reactor for compound semiconductor growth, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Horizontal reactor for compound semiconductor growth will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2472457