CN103474331B

CN103474331B - The growing epitaxial method of AlN template on a sapphire substrate

Info

Publication number: CN103474331B
Application number: CN201310461033.1A
Authority: CN
Inventors: 赵红; 李艳炯
Original assignee: CETC 44 Research Institute
Current assignee: CETC 44 Research Institute
Priority date: 2013-10-08
Filing date: 2013-10-08
Publication date: 2016-03-23
Anticipated expiration: 2033-10-08
Also published as: CN103474331A

Abstract

A method for growing epitaxial AlN template on a sapphire substrate, its scheme is: take trimethyl aluminium as MO source, NH ₃for gaseous source, metalorganic chemical vapor depositing operation is adopted to grow AlN template at sapphire surface; When growing AIN template, trimethyl aluminium is prior to NH ₃pass in reative cell, postpone 1-5 after passing into trimethyl aluminium and pass into NH again second ₃, NH ₃generate AlN after reacting with the Al atom being attached to sapphire surface, finally grow AlN template at sapphire surface; NH ₃with V/III of trimethyl aluminium than being 51 ~ 256, reative cell internal gas pressure is 20 ~ 50mbar, and temperature is 1200 DEG C.Advantageous Effects of the present invention is: method simple practical, does not need resilient coating, can under relatively low underlayer temperature (1200 DEG C), and grow the AlN template that surface atom level is smooth, AlN template mean roughness is about 0.5nm.

Description

The growing epitaxial method of AlN template on a sapphire substrate

Technical field

The present invention relates to a kind of Organic Chemical Vapor deposition (MOCVD) technique, particularly relate to a kind of method of the AlN of growing epitaxial on a sapphire substrate template.

Background technology

At present, be both at home and abroad that the nitride epitaxial growth technology of substrate is very ripe with sapphire/GaN, but for deep UV (ultraviolet light) electronic device, because GaN material will cause the serious reduction of device light emitting efficiency to the strong absorption effect of ultraviolet light, nearly all incident light all can be absorbed by GaN layer and cannot be with source region generation photoelectric current, and the nitride template being therefore substrate with sapphire/GaN is not suitable for for making deep UV (ultraviolet light) electronic device; In order to solve foregoing problems, a kind of comparatively feasible technology path is: discard GaN template, is directly having deep UV (ultraviolet light) well through the AlGaN epitaxial loayer of the Grown on Sapphire Substrates high Al contents of characteristic.

The AlGaN epitaxial loayer of growth high Al contents, optimal substrate should be the ultraviolet light that AlN, AlN crystal is greater than 200nm to wavelength is all transparent, and AlN and AlGaN can form good Lattice Matching, and AlN also has good thermal conductance (thermal conductivity 3Wcm ^-1k ^-1), be conducive to the high-power performance improving device. in addition, owing to there is the maximum velocity of sound (6200m/s), higher piezoelectric coupling coefficient in all known SAW filter materials, AlN or a kind of desirable radio frequency SAW filter materials; But the technology of preparing of AlN single crystalline substrate is also immature, expensive both at home and abroad at present, and supply of material difficulty (especially large-sized substrate).

2006, the people such as SoukhoveevV report and adopt HVPE(hydride gas-phase epitaxy) method successfully grows high-quality AlN template on a sapphire substrate, but the AlN template obtained by HVPE method cannot make follow-up device epitaxial structure in growth in situ mode, therefore technical process relative complex, from the viewpoint of reducing process complexity, be necessary the technology of exploration MOCVD method direct growth AlN template on a sapphire substrate.

Summary of the invention

For the problem in background technology, the present invention proposes a kind of method of the AlN of growing epitaxial on a sapphire substrate template, its innovation is: take trimethyl aluminium as MO source, NH ₃for gaseous source, metalorganic chemical vapor depositing operation is adopted to grow AlN template at sapphire surface; When growing AIN template, trimethyl aluminium is prior to NH ₃pass in reative cell, postpone 1-5 after passing into trimethyl aluminium and pass into NH again second ₃, NH ₃generate AlN after reacting with the Al atom being attached to sapphire surface, finally grow AlN template at sapphire surface; NH ₃with V/III of trimethyl aluminium than being 51 ~ 256, reative cell internal gas pressure is 20 ~ 50mbar, and temperature is 1200 DEG C.

Principle of the present invention is: the present invention passes into NH after adopting and first passing into trimethyl aluminium ₃mode carry out growing AIN template, pass into trimethyl aluminium in advance, can make sapphire surface to adhere in advance last layer Al atom, avoid NH ₃directly contact with sapphire surface and cause sapphire surface by nitrogenize, effectively to suppress the AlN film with mixing polar crystal domain to produce, improving the homogeneity of the AlN speed of growth.The present invention adopts low V/III than carrying out growing AIN template, growth technique of the prior art generally adopts 700 ~ 800 high V/III than carrying out, high V/III reduces in substrate surface animal migration than causing Al atom, be unfavorable for the foundation of two dimensional mode, be also just unfavorable for the formation of smooth epitaxial surface.The reative cell air pressure of present invention process is lower, and low reaction room air pressure effectively can reduce NH ₃with trimethyl aluminium reactivity in the gas phase, thus reduce because of NH ₃react in the gas phase with trimethyl aluminium and generate dust granules and be deposited on substrate, meanwhile, under the acting in conjunction of low reaction room air pressure and low V/III ratio, the animal migration of Al atom on substrate can be improved further.

Preferably, trimethyl aluminium flow is 40 ~ 80sccm, NH3 flow is 80 ~ 200sccm.

Preferably, before growing AIN template, be 1200 ~ 1250 DEG C in temperature, under pressure is 90 ~ 110mbar, carrier gas flux is the condition of 5000 ~ 7000sccm, removal of impurities carried out to sapphire surface.

Preferably, described AlN template thickness is 1 μm.AlN template thickness regulates by controlling the reaction time, if AlN template thickness is comparatively large, easily occurs crackle.

Advantageous Effects of the present invention is: method simple practical, does not need resilient coating, can under relatively low underlayer temperature (1200 DEG C), and grow the AlN template that surface atom level is smooth, AlN template mean roughness is about 0.5nm.

Embodiment

A method for growing epitaxial AlN template on a sapphire substrate, its innovation is: take trimethyl aluminium as MO source, NH ₃for gaseous source, metalorganic chemical vapor depositing operation is adopted to grow AlN template at sapphire surface; When growing AIN template, trimethyl aluminium is prior to NH ₃pass in reative cell, postpone 1-5 after passing into trimethyl aluminium and pass into NH again second ₃, NH ₃generate AlN after reacting with the Al atom being attached to sapphire surface, finally grow AlN template at sapphire surface; NH ₃with V/III of trimethyl aluminium than being 51 ~ 256, reative cell internal gas pressure is 20 ~ 50mbar, and temperature is 1200 DEG C.

Further, trimethyl aluminium flow is 40 ~ 80sccm, NH3 flow is 80 ~ 200sccm.

Further, before growing AIN template, be 1200 ~ 1250 DEG C in temperature, under pressure is 90 ~ 110mbar, carrier gas flux is the condition of 5000 ~ 7000sccm, removal of impurities carried out to sapphire surface.

Further, described AlN template thickness is 1 μm.

Embodiment:

Sapphire Substrate is loaded in the reative cell of MOCVD device, in the environment of 1200 DEG C of underlayer temperatures, 100mbar Hydrogen Vapor Pressure, 6000sccm carrier gas flux, toasts 10 minutes, eliminate surface impurity; Reative cell internal gas pressure is adjusted to 40mbar, underlayer temperature is adjusted to 1200 DEG C, in reative cell, pass into trimethyl aluminium, trimethyl aluminium flow is 60sccm, postpones after 3 seconds, in reative cell, passes into NH ₃, by controlling the reaction time, sapphire surface is grown AlN template that thickness is 1 μm.

Claims

1. a growing epitaxial method for AlN template on a sapphire substrate, is characterized in that: take trimethyl aluminium as MO source, NH ₃for gaseous source, metalorganic chemical vapor depositing operation is adopted to grow AlN template at sapphire surface; When growing AIN template, trimethyl aluminium is prior to NH ₃pass in reative cell, postpone 1-5 after passing into trimethyl aluminium and pass into NH again second ₃, NH ₃generate AlN after reacting with the Al atom being attached to sapphire surface, finally grow AlN template at sapphire surface; NH ₃with V/III of trimethyl aluminium than being 51 ~ 256, reative cell internal gas pressure is 20 ~ 50mbar, and temperature is 1200 DEG C.

2. the method for the AlN of growing epitaxial on a sapphire substrate template according to claim 1, is characterized in that: trimethyl aluminium flow is 40 ~ 80sccm, NH3 flow is 80 ~ 200sccm.

3. the method for the AlN of growing epitaxial on a sapphire substrate template according to claim 1, it is characterized in that: before growing AIN template, be 1200 ~ 1250 DEG C in temperature, under pressure is 90 ~ 110mbar, carrier gas flux is the condition of 5000 ~ 7000sccm, removal of impurities carried out to sapphire surface.

4. the method for the AlN of growing epitaxial on a sapphire substrate template according to claim 1, is characterized in that: described AlN template thickness is 1 μm.