CN107541785A - A kind of in-situ annealing technique of aluminum nitride crystal - Google Patents
A kind of in-situ annealing technique of aluminum nitride crystal Download PDFInfo
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- CN107541785A CN107541785A CN201710816684.6A CN201710816684A CN107541785A CN 107541785 A CN107541785 A CN 107541785A CN 201710816684 A CN201710816684 A CN 201710816684A CN 107541785 A CN107541785 A CN 107541785A
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Abstract
The present invention relates to a kind of in-situ annealing technique of aluminum nitride crystal, in-situ annealing is carried out after the completion of being grown in aluminum nitride crystal growth room, from during seed crystal aluminum nitride crystal growth, by configuring heat conduction platform inside crucible, cold-trap platform is configured above substrate bracket, heat conduction platform imports into crucible the high temperature of crucible wall by way of heat transfer, high-temperature region is formed around seed crystal, crystal seed back temperature is exported by cold-trap platform, low-temperature space is formed on seed crystal, therefore except seed crystal is low-temperature space above crucible, remaining is high-temperature region.The high temperature of seed crystal periphery causes the region to have relatively low nitridation aluminum vapor degree of supersaturation, therefore suppresses the growth of aluminium nitride polycrystalline, and the low temperature at seed crystal causes the region to have higher nitridation aluminum vapor degree of supersaturation, promotes aluminium nitride growth rate to improve.
Description
Technical field
The present invention relates to a kind of annealing process of aluminum nitride crystal, the in-situ annealing work of more particularly to a kind of aluminum nitride crystal
Skill.
Background technology
Aluminium nitride is direct band-gap semicondictor material, and its energy gap is 6.2eV, disruptive field intensity is 11.7 × 106V•cm-1, thermal conductivity measured value be 2.85W cm-1•K-1And with excellent heat endurance and corrosion resistance, good optical property
And mechanical property.Aluminum-nitride single crystal, can not also with other substrates when as the substrate of AlGaN bases and GaN base epitaxial material
The advantage of analogy, such as both category materials of the same clan, lattice mismatch is small, and lattice mismatch is up to 2.4%.The heat of aluminium nitride and AlGaN
The coefficient of expansion is closest, in growth and cooling procedure prepared by device, can avoid the cracking of epitaxial structure, dislocation density
It can reduce more than 2 orders of magnitude.As generation semiconductor material, aluminium nitride material, will be in photoelectron with its excellent performance
There is highly important application with microelectronic.
Physical vapor transmission (PVT) method is acknowledged as one of growing aluminum nitride crystal most efficient method.PVT methods nitrogenize
Aluminium growth strategy is divided into three kinds, respectively spontaneous nucleation aluminum nitride crystal growth, SiC seed crystals aluminum nitride crystal growth and from seed crystal
Aluminum nitride crystal growth.However, three kinds of crystal growth strategies are faced with the problem of stress between crystal simultaneously, it is mainly manifested in following
Aspect：
（1）Stress problem in SiC seed crystals：SiC seed crystals be excuse me, but I must be leaving now there is larger lattice with AlN crystal and be excuse me, but I must be leaving now with heat, and
During AlN crystal growth, a large amount of defects in AlN crystal are result in due to SiC decomposition, therefore cause SiC seed crystals to obtain
AlN in there is very big stress, stress can not discharge in the engineering that cools, thus using SiC seeded growths AlN crystal in
With substantial amounts of micro-crack, or even cracking；
（2）Spontaneous nucleation：Aluminium nitride thermal coefficient of expansion has extremely strong anisotropy, if a is to thermalexpansioncoefficientαa=4.2×10-6
K-1, c is to thermalexpansioncoefficientαc=5.3×10-6K, therefore in spontaneous nucleation AlN quartz crystal growth courses, between different radial directions
Crystal grain interval mutually extruding will cause stress between crystal, cause crackle between crystal；
（3）Aluminium nitride seeded growth：There is damaging layer and subdamage layer, this causes to grow crystal and seed aluminium nitride seed crystal face
The defects of between crystalline substance stress, in addition, the multicenter growth pattern of aluminium nitride seed crystal will cause organic centre to be completely integrated, shape
Into defect, cause crystal stress；
（4）Common problem：Substrate（Tungsten or ramet）Heat between seed crystal, which excuse me, but I must be leaving now to be adapted to lattice, causes crystal stress, in addition,
Longitudinally and radially thermograde on crucible and crucible cover also results in crystal stress.
The content of the invention
In view of the problem of prior art is present, for stress Producing reason between the growing crystals of aluminum nitride crystal, divides
Analyse the temperature that crystal cleavage occurs, the present invention provides a kind of in-situ annealing technique of aluminum nitride crystal, with solve aluminium nitride due to
Defect in crystal caused by stress concentration, or even the problem of cracking, concrete technical scheme is that a kind of original position of aluminum nitride crystal is moved back
Ignition technique, it is characterised in that：In-situ annealing is carried out after the completion of being grown in aluminum nitride crystal growth room, annealing process includes, and 1）、
800 DEG C, 1200 DEG C, 1500 DEG C, 1800 DEG C, 2000 DEG C or 2200 DEG C of tempering process temperature spot in situ being selected in temperature-fall period
Middle 1-6 tempering process temperature spot；2）, select each tempering process temperature spot warming temperature be 50 ~ 350 DEG C；3）, add annealing
Atmosphere, annealing atmosphere can be one or more of mixing in nitrogen, argon gas, hydrogen, and annealing gas pressure is 0.5atm ~ 3atm；4）, drop
Temperature, rate of temperature fall are less than or equal to 5 DEG C/min；5）, when temperature drops to first paragraph tempering process temperature spot, start tempering process,
Warming temperature claims first paragraph tempering process warming temperature, and tempering heating rate is less than or equal to 5 DEG C/min, and soaking time is 2 ~ 8h；
6）, when cooling drop to second segment to the 6th section of tempering process temperature spot respectively when, respectively repeat steps 5 tempering process；7）, it is natural
Aluminum nitride crystal is taken out when being cooled to outdoor temperature, completes in-situ annealing.
The present invention operation principle be：
From during seed crystal aluminum nitride crystal growth, by configuring heat conduction platform inside crucible, cold-trap is configured above substrate bracket
Platform, the high temperature distribution around seed crystal and the low-temperature space at the seed crystal back side are realized, the controllable temperature trap formed near seed crystal support, avoids seed
Polycrystalline growth around brilliant, growth rate is improved, reaches thick crystals growth purpose of the aluminium nitride from seed crystal.Use conventional crucibles（I.e.
Straight barrel type crucible）During growing aluminum nitride crystal, because crucible substrate terminal temperature is respectively less than temperature at raw material, and radially without very
Big temperature difference, cause to produce heterogeneous forming core in sidewall of crucible and edges of substrate, form polycrystalline growth.It is warm at substrate by improving
The method of degree can suppress polycrystalline growth, but such a method can cause crystal growth degree of supersaturation low, and crystal growth latent heat is released
Slow down the problems such as slow, to making crystal growth rate slow.During using temperature trap device growing aluminum nitride crystal of the invention, heat conduction
Platform imports into crucible the high temperature of crucible wall by way of heat transfer, and high-temperature region, crystal seed are formed around seed crystal
Back temperature is exported by cold-trap platform 1, and low-temperature space is formed on seed crystal, therefore except seed crystal is low-temperature space above crucible, remaining
It is high-temperature region.The high temperature of seed crystal periphery causes the region to have relatively low nitridation aluminum vapor degree of supersaturation, therefore suppresses nitridation
Aluminium polycrystalline grows, and the low temperature at seed crystal causes the region to have higher nitridation aluminum vapor degree of supersaturation, promotes aluminium nitride life
Long speed improves.
It is an advantage of the invention that by carrying out in-situ annealing to the aluminum nitride crystal of acquisition, and carry out at different temperatures
Temper, can not only suppress the cooling problem of Cracking of aluminum nitride crystal, can also reduce stress and intrinsic defect between crystal, carry
The crystal mass of high aluminium nitride, the annealing process are simple and easy to do.
Embodiment
Embodiment 1
The growing aluminum nitride by the way of spontaneous nucleation, the annealing process used are 5 DEG C/min for annealing rate, and temperature is
1200 DEG C and 1800 DEG C, tempering process heating rate is 5 DEG C/min, and warming temperature is 200 DEG C, soaking time 4h, gas of annealing
Atmosphere is nitrogen, annealing gas pressure 1.5atm.Crystal does not ftracture in the present embodiment.
Embodiment 2
The growing aluminum nitride by the way of SiC seed crystals, the annealing process used are 4 DEG C/min for annealing rate, and temperature is
800 DEG C, 1200 DEG C and 1500 DEG C, tempering process heating rate is 4 DEG C/min, and warming temperature is 100 DEG C, soaking time 2h,
Annealing atmosphere is the mixed gas of nitrogen and argon gas, and annealing gas pressure is 0.8 atm.Crystal does not ftracture in the present embodiment.
Embodiment 3
The growing aluminum nitride by the way of aluminium nitride seed crystal, the annealing process used are 5 DEG C/min for annealing rate, temperature
For 1200 DEG C, 1500 DEG C, 1800 DEG C and 2200 DEG C, tempering process heating rate is 5 DEG C/min, and warming temperature is 150 DEG C, insulation
Time is 2h, and annealing atmosphere is nitrogen gas, and annealing gas pressure is 1.2 atm.Crystal does not ftracture in the present embodiment.
It is noted that simply the present invention is described in detail for above-mentioned embodiment, it should not be to the present invention
Limitation.For a person skilled in the art, when without departing from the objective and scope of claim, there can be diversified forms
With the change of details.
Claims (1)
- A kind of 1. in-situ annealing technique of aluminum nitride crystal, it is characterised in that：After the completion of being grown in aluminum nitride crystal growth room i.e. In-situ annealing is carried out, annealing process includes,1）, 800 DEG C, 1200 DEG C, 1500 DEG C, 1800 DEG C, 2000 DEG C of tempering process temperature spot in situ being selected in temperature-fall period Or 1-6 tempering process temperature spot in 2200 DEG C；2）, select each tempering process temperature spot warming temperature be 50 ~ 350 DEG C；3）, add annealing atmosphere, annealing atmosphere can be nitrogen, argon gas, one or more of mixing in hydrogen, and annealing gas pressure be 0.5atm~3atm；4）, cooling, rate of temperature fall is less than or equal to 5 DEG C/min；5）, when temperature drops to first paragraph tempering process temperature spot, start tempering process, warming temperature claims first paragraph tempering process Warming temperature, tempering heating rate are less than or equal to 5 DEG C/min, and soaking time is 2 ~ 8h；6）, when cooling drop to second segment to the 6th section of tempering process temperature spot respectively when, respectively repeat steps 5 tempering process；7）, be naturally cooling to take out aluminum nitride crystal during outdoor temperature, complete in-situ annealing.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2021064000A1 (en) * | 2019-10-01 | 2021-04-08 | Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. | Method for reducing structural damage to the surface of monocrystalline aluminium-nitride substrates, and monocrystalline aluminium-nitride substrates that can be produced by a method of this type |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102534805A (en) * | 2010-12-14 | 2012-07-04 | 北京天科合达蓝光半导体有限公司 | Silicon carbide crystal annealing process |
| CN105525355A (en) * | 2015-11-06 | 2016-04-27 | 浙江露通机电有限公司 | In-situ annealing process for large-size sapphire crystal |
| CN106435741A (en) * | 2016-09-23 | 2017-02-22 | 江苏吉星新材料有限公司 | Large-size sapphire annealing process |
-
2017
- 2017-09-12 CN CN201710816684.6A patent/CN107541785A/en active Pending
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102534805A (en) * | 2010-12-14 | 2012-07-04 | 北京天科合达蓝光半导体有限公司 | Silicon carbide crystal annealing process |
| CN105525355A (en) * | 2015-11-06 | 2016-04-27 | 浙江露通机电有限公司 | In-situ annealing process for large-size sapphire crystal |
| CN106435741A (en) * | 2016-09-23 | 2017-02-22 | 江苏吉星新材料有限公司 | Large-size sapphire annealing process |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2021064000A1 (en) * | 2019-10-01 | 2021-04-08 | Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. | Method for reducing structural damage to the surface of monocrystalline aluminium-nitride substrates, and monocrystalline aluminium-nitride substrates that can be produced by a method of this type |
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