CN102719887B

CN102719887B - Method for growing high-quality gallium nitride epitaxial film on basis of gallium nitride substrate

Info

Publication number: CN102719887B
Application number: CN201210193466.9A
Authority: CN
Inventors: 李亮
Original assignee: CETC 55 Research Institute
Current assignee: CETC 55 Research Institute
Priority date: 2012-06-13
Filing date: 2012-06-13
Publication date: 2014-12-10
Anticipated expiration: 2032-06-13
Also published as: CN102719887A

Abstract

The invention relates to a method for growing a high-quality gallium nitride epitaxial film on the basis of a gallium nitride substrate. The method is carried out in MOCVD (metal organic chemical vapor deposition) equipment and includes the following steps of selecting a substrate, placing the substrate into an MOCVD reaction chamber, heating and baking the substrate; introducing ammonia gas (NH3) for nitriding the substrate; cooling to the growth temperature and introducing trimethyl gallium (TMG) and the ammonia gas (NH3) at the same time; growing a first gallium nitride (GaN) optimized layer at lower pressure and high V/III, and growing a second layer of a high-quality GaN epitaxial film by boosting the pressure and reducing the V/III. The method for growing a high-quality gallium nitride epitaxial film on the basis of the gallium nitride substrate has the advantages that the method is simple and practical and is an effective resolution for growing high-quality low-cost GaN epitaxial films, and the growing period is short, materials are fine in performance.

Description

A kind of growth method of the high-quality gallium nitride epitaxial film based on gallium nitride substrate

Technical field

What the present invention relates to is a kind of growth method of the high-quality gallium nitride epitaxial film based on gallium nitride substrate, belongs to technical field of semiconductors.

Background technology

Gan (GaN) material is as one of third generation semiconductor material representative, there is the excellent properties such as direct band gap, broad stopband, high saturated electron drift velocity, high breakdown electric field and high heat conductance, excellent physical and chemical stability, aspect microelectronic applications, obtain paying close attention to widely, can make high temperature, high frequency and high power device, as High Electron Mobility Transistor (HEMT), heterojunction bipolar transistor (HBT) etc.In addition, nitride multicomponent material taking gan as representative can band gap from 0.7eV to 6.2eV, its luminescent spectrum scope covers from infrared to ultraviolet wavelength, aspect optoelectronic applications, as blue light, green glow, ultraviolet light-emitting diodes (LED), short wavelength laser diode (LD), the aspects such as ultraviolet detector, Bragg reflection waveguide have also obtained important application and development.

But, due to the special property of gallium nitride material, adopt traditional method for monocrystal growth to be difficult to grow monocrystalline, therefore gallium nitride substrate cannot effectively solve for a long time.At present, the epitaxy of gallium nitride material mainly adopts foreign substrate, and as sapphire, silicon carbide (SiC), silicon (Si) etc., ubiquity the problem that the epitaxial material defect concentration of bringing due to lattice mismatch and thermal mismatching is large etc.Therefore, in foreign substrate, carry out GaN epitaxial film while preparing, must adopt two-step growth method, first carry out the growth of low temperature nucleating layer, then carry out high temperature annealing, make nucleating layer decomposed recrystallize be formed into nuclear island, then carry out high temperature epitaxy growth.The GaN epitaxial material crystal mass that adopts this method to obtain is significantly improved, and because GaN material is in the luminous impact that is not substantially subject to fault in material of some wave band, thereby substantially solve the application of GaN sill aspect semiconductor light emitting.The fast development of the LED of GaN base illumination in the last few years, is widely used in indicating meter, pilot lamp, billboard, traffic lights etc.But the high density material defect existing in GaN hetero epitaxy film has still affected the practical progress of GaN sill in microelectronic, field of lasers and ultraviolet LED field etc. greatly.Recently, utilize the high growth rates of hydride gas-phase epitaxy (HVPE) and the characteristic of higher crystalline quality, realized the thick film growth of GaN material, more than its thickness can reach hundreds of micron.Prepared the GaN material substrate of self-supporting based on this method.The present invention adopts the GaN substrate of this self-supporting.Owing to being iso-epitaxy, there is not the problem of lattice mismatch and mismatch stress, therefore can carry out the growth of low temperature nucleating layer and annealing, directly carry out high temperature epitaxy growth, thereby realized the growth of high-quality GaN epitaxial film.

Summary of the invention

The present invention is to provide a kind of growth method of the high-quality gallium nitride epitaxial film based on gallium nitride substrate, its object is intended to by adopting GaN substrate, realize isoepitaxial growth, simplify epitaxial growth technology, fundamentally eliminate the impact of lattice mismatch stress on epitaxial film, thereby obtain high-quality GaN epitaxial film; Growth phase adopts and reduces chamber pressure in the early stage, the method that increases V/III increases transverse growth speed, promote dislocation to merge, stop substrate dislocation to derive to epitaxial film, the chamber pressure that then raises, reduces V/III, proceeds GaN epitaxial film growth, to increase reactant utilization ratio, reduce process costs.

Technical solution of the present invention: it is characterized in that the method comprises the steps:

1) select a substrate (1), this substrate is 0001 self-support gallium nitride substrate material;

2) substrate (1) is put into metal-organic chemical vapor deposition equipment system, pass into H ₂, chamber pressure is 100torr-200torr, at 1050 DEG C-1100 DEG C, heats 3min-5min, with clean substrate surface, removes surface contamination;

3) reaction chamber temperature is down to 1000 DEG C-1050 DEG C, passes into high-purity ammonia and carries out nitrogenize, H ₂as carrier gas; Chamber pressure is 300torr-500torr, and nitridation time is 1min-3min;

4) cool the temperature to 980-1020 DEG C, reduce chamber pressure to 50torr-100torr, continue to pass into ammonia, pass into trimethyl-gallium, taking V/III as 3500-5000 epitaxial growth of gallium nitride Optimization Layer (2), thickness 200nm simultaneously;

5) temperature is remained on to 980 DEG C, rising chamber pressure, to 300torr-500torr, continues to pass into ammonia, pass into trimethyl-gallium simultaneously, taking V/III as 1500-2000 epitaxy high-quality gallium nitride epitaxial film (3), thickness 1800nm, hydrogen is as carrier gas.

Advantage of the present invention: the GaN epitaxial film crystal mass obtaining is high, and surface finish is high, dislocation desity <1 × 10 ⁷cm ^-2.The inventive method is simple, and growth cycle is short, and material property is good, is to realize GaN epitaxial film high quality, low cost growth.Overcome the existing above-mentioned defect of prior art.

Brief description of the drawings

Fig. 1 is the high-quality gallium nitride epitaxial film growth structural representation based on gallium nitride substrate of the present invention.

Fig. 2 is high-quality gallium nitride epitaxial film high resolution X ray rocking curve peak width at half height test result of the present invention.

Fig. 3 is the surface topography map of high-quality gallium nitride epitaxial film of the present invention under atomic force microscope.

In figure 1 is substrate, the 2nd, GaN Optimization Layer, the 3rd, GaN film.

Embodiment

Embodiment 1

As shown in Figure 1, the growth method of a kind of high-quality gallium nitride epitaxial film based on gallium nitride substrate of the present invention, is characterized in that, comprises the steps:

1) select a substrate 1, this substrate is 0001 self-support gallium nitride substrate material;

2) substrate 1 is put into metal-organic chemical vapor deposition equipment system, pass into H ₂, chamber pressure is 100torr, at 1050 DEG C, heats 5min, with clean substrate surface, removes surface contamination;

3) reaction chamber temperature is down to 1000 DEG C, passes into high-purity ammonia and carries out nitrogenize, H ₂as carrier gas.Chamber pressure is 300torr, and nitridation time is 3min;

4) cool the temperature to 1020 DEG C, reduce chamber pressure to 50torr, continue to pass into ammonia, pass into trimethyl-gallium, taking V/III as 3500 epitaxy GaN Optimization Layer 2, thickness 200nm simultaneously;

5) temperature is remained on to 980 DEG C, rising chamber pressure, to 300torr, continues to pass into ammonia, passes into trimethyl-gallium simultaneously, taking V/III as 1500 grow high quality GaN film by MOCVDs 3, thickness 1800nm.

Embodiment 2

2) substrate 1 is put into metal-organic chemical vapor deposition equipment system, pass into H ₂, chamber pressure is 200torr, at 1100 DEG C, heats 3min, with clean substrate surface, removes surface contamination;

3) reaction chamber temperature is down to 1050 DEG C, passes into high-purity ammonia and carries out nitrogenize, H ₂as carrier gas.Chamber pressure is 500torr, and nitridation time is 1min;

4) cool the temperature to 980 DEG C, reduce chamber pressure to 100torr, continue to pass into ammonia, pass into trimethyl-gallium, taking V/III as 5000 epitaxy GaN Optimization Layer 2, thickness 200nm simultaneously;

5) temperature is remained on to 980 DEG C, rising chamber pressure, to 500torr, continues to pass into ammonia, passes into trimethyl-gallium simultaneously, taking V/III as 2000 grow high quality GaN film by MOCVDs 3, thickness 1800nm.

The sample being obtained by above step is carried out to test analysis, prove that the epitaxy of gallium nitride thin film crystallization quality of the growth of method is thus high and surface finish is high.

Adopt high resolution X-ray diffraction testing method to show that the epitaxy of gallium nitride film that (as shown in Figure 2) present method obtains is that 0002 rocking curve peak width at half height is only 120 second of arcs, dislocation desity <1 × 10 ⁷cm ^-2, crystalline quality is high.

Adopt atomic force microscope testing method to characterize the surface topography (as shown in Figure 3) of this sample, photo size is 1 μ m × 1 μ m.Result shows, the epitaxy of gallium nitride film surface that present method obtains has very high surface finish, and surfaceness RMS is only 0.12nm.

The present invention carries out in MOCVD equipment, comprises baking, nitrogenize and epitaxy stage.

Adopt MOCVD method growing high-quality GaN epitaxial film, comprise baking, nitrogenize and epitaxy stage;

Described GaN substrate is GaN substrate prepared by the Free-standing GaN substrate prepared by HVPE method or other method;

The described baking stage is at high temperature, uses H ₂gaN substrate surface is carried out to etching, remove surface contamination;

The described nitrogenize stage is at high temperature, uses high-purity N H ₃nitrogenize is carried out in GaN surface, form initial GaN layer material;

The described epitaxy stage is at high temperature, adopts low pressure and high V/III, growth regulation one deck GaN Optimization Layer, and reaction chamber pressure reduce the V/III second floor height quality GaN epitaxial film of growing then raises.

The present invention, by adopting GaN substrate, realizes isoepitaxial growth, simplifies epitaxial growth technology, fundamentally eliminates the impact of lattice mismatch stress on epitaxial film, thereby obtains high-quality GaN epitaxial film.Growth phase adopts and reduces chamber pressure in the early stage, the method that increases V/III increases transverse growth speed, promote dislocation to merge, stop substrate dislocation to derive to epitaxial film, the chamber pressure that then raises, reduces V/III, proceeds GaN epitaxial film growth, to increase reactant utilization ratio, reduce process costs.The GaN epitaxial film crystal mass that the inventive method obtains is high, and surface finish is high, dislocation desity <1 × 10 ⁷cm ^-2.The inventive method is simple, and growth cycle is short, and material property is good, is to realize GaN epitaxial film high quality, low cost growth.

Claims

1. a growth method for the high-quality gallium nitride epitaxial film based on gallium nitride substrate, is characterized in that the method comprises the steps: