CN102719887A

CN102719887A - Method for growing high-quality gallium nitride epitaxial film on basis of gallium nitride substrate

Info

Publication number: CN102719887A
Application number: CN2012101934669A
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: 2012-10-10
Anticipated expiration: 2032-06-13
Also published as: CN102719887B

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 the gan 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 the gan substrate, belongs to technical field of semiconductors.

Background technology

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

But, because the special property of gallium nitride material adopt traditional method for monocrystal growth to be difficult to grow monocrystalline, so the gan substrate can't effectively solve for a long time.At present, foreign substrate is mainly adopted in the epitaxy of gallium nitride material, and like sapphire, silit (SiC), silicon (Si) etc., ubiquity because big etc. the problem of the epitaxial material defect concentration that lattice mismatch and thermal mismatching are brought.Therefore, on foreign substrate, carry out the GaN epitaxial film when preparing, must adopt two one-step growth methods, carry out the growth of low temperature nucleating layer earlier, then carry out high temperature annealing, nucleating layer is partly decomposed and recrystallize is formed into nuclear island, carry out the high temperature epitaxy growth then.The GaN epitaxial material crystal mass that adopts this method to obtain is significantly improved, and owing to the luminous influence that basically do not receive fault in material of GaN material at some wave band, thereby solved the application of GaN sill aspect semiconductor light emitting basically.The LED illumination fast development of GaN base was widely used in indicating meter, PL, billboard, traffic lights etc. in the last few years.But the high density material defective that in GaN hetero epitaxy film, exists has still influenced the practicability 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, its thickness can reach more than the 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 be iso-epitaxy, there is not the problem of lattice mismatch and mismatch stress, therefore can carry out growth of low temperature nucleating layer and annealing, directly carry out the 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 the gan substrate; Its purpose is intended to through adopting the GaN substrate; Realize isoepitaxial growth; Simplify epitaxial growth technology, fundamentally eliminate of the influence of lattice mismatch stress, thereby obtain the high-quality GaN epitaxial film epitaxial film; Growth phase adopts and reduces chamber pressure in the early stage, and the method that increases V/III increases lateral growth speed, promotes dislocation to merge; Stop the substrate dislocation to be derived to epitaxial film; The chamber pressure that then raises reduces V/III, proceeds the GaN epitaxial film growth; To increase the reactant utilization ratio, reduce the technology cost.

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

1) select a substrate (1), this substrate is 0001 self-standing gan substrate material;

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

3) reaction chamber temperature is reduced to 1000 ℃-1050 ℃, feeds high-purity ammonia and carries out nitrogenize, H ₂As carrier gas; Chamber pressure is 300torr-500torr, and nitridation time is 1min-3min;

4) cooling the temperature to 980-1020 ℃, reduce chamber pressure to 50torr-100torr, continue to feed ammonia, feed trimethyl-gallium simultaneously, is 3500-5000 epitaxial growth of gallium nitride Optimization Layer (2) with V/III, thickness 200nm;

5) temperature is remained on 980 ℃, the rising chamber pressure continues to feed ammonia to 300torr-500torr; Feed trimethyl-gallium simultaneously; With V/III is 1500-2000 epitaxy high-quality gallium nitride epitaxial film (3), thickness 1800nm, and hydrogen is as carrier gas.

Advantage of the present invention: the GaN epitaxial film crystal mass that is obtained is high, and surface finish is high, dislocation desity<1 * 10 ⁷Cm ^-2The 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 above-mentioned defective of existing in prior technology.

Description of drawings

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

Fig. 2 is a high-quality gallium nitride epitaxial film high resolution X ray rocking curve peak width at half 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 AFM.

Among the 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 the gan substrate of the present invention is characterized in that, comprises the steps:

1) select a substrate 1, this substrate is 0001 self-standing gan substrate material;

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

3) reaction chamber temperature is reduced to 1000 ℃, feeds high-purity ammonia and carries out nitrogenize, H ₂As carrier gas.Chamber pressure is 300torr, and nitridation time is 3min;

4) cooling the temperature to 1020 ℃, reduce chamber pressure to 50torr, continue to feed ammonia, feed trimethyl-gallium simultaneously, is 3500 epitaxy GaN Optimization Layer 2 with V/III, thickness 200nm;

5) temperature is remained on 980 ℃, the rising chamber pressure continues to feed ammonia to 300torr, feeds trimethyl-gallium simultaneously, is 1500 epitaxy high-quality GaN films 3 with V/III, thickness 1800nm.

Embodiment 2

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

3) reaction chamber temperature is reduced to 1050 ℃, feeds high-purity ammonia and carries out nitrogenize, H ₂As carrier gas.Chamber pressure is 500torr, and nitridation time is 1min;

4) cooling the temperature to 980 ℃, reduce chamber pressure to 100torr, continue to feed ammonia, feed trimethyl-gallium simultaneously, is 5000 epitaxy GaN Optimization Layer 2 with V/III, thickness 200nm;

5) temperature is remained on 980 ℃, the rising chamber pressure continues to feed ammonia to 500torr, feeds trimethyl-gallium simultaneously, is 2000 epitaxy high-quality GaN films 3 with V/III, thickness 1800nm.

Sample to being obtained by above step carries out test analysis, proves that the epitaxy of gallium nitride thin film crystallization quality height of method growth thus and surface finish are 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 is merely 120 second of arcs, dislocation desity<1 * 10 ⁷Cm ^-2, crystalline quality is high.

Adopt the AFM testing method to characterize the surface topography (as shown in Figure 3) of this sample, photo size is 1 μ m * 1 μ m.The result shows that the epitaxy of gallium nitride film surface that present method obtained has very high surface finish, and surfaceness RMS is merely 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;

Said GaN substrate is the GaN substrate by the self-supporting GaN substrate of HVPE method preparation or the preparation of other method;

The said baking stage is at high temperature, uses H ₂The GaN substrate surface is carried out etching, remove surface contamination;

The said nitrogenize stage is at high temperature, uses high-purity N H ₃Nitrogenize is carried out on the GaN surface, formed initial GaN layer material;

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

The present invention realizes isoepitaxial growth through adopting the GaN substrate, simplifies epitaxial growth technology, fundamentally eliminates the influence of lattice mismatch stress to epitaxial film, thereby obtains the high-quality GaN epitaxial film.Growth phase adopts and reduces chamber pressure in the early stage, and the method that increases V/III increases lateral growth speed, promotes dislocation to merge; Stop the substrate dislocation to be derived to epitaxial film; The chamber pressure that then raises reduces V/III, proceeds the GaN epitaxial film growth; To increase the reactant utilization ratio, reduce the technology cost.The GaN epitaxial film crystal mass that the inventive method obtained is high, and surface finish is high, dislocation desity<1 * 10 ⁷Cm ^-2The 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. the growth method based on the high-quality gallium nitride epitaxial film of gan substrate is characterized in that this method comprises the steps: