摘要
氧化镓(β-Ga2O3)单晶是继碳化硅(SiC)和氮化镓(GaN)之后,制造超高压功率器件、深紫外光电子器件、高亮度LED等高性能半导体器件的新一代半导体材料,大尺寸低缺陷氧化镓单晶的制备方法以及高表面质量氧化镓晶片的超精密加工技术是实现氧化镓半导体器件工业应用的瓶颈之一。针对易产生结构缺陷的氧化镓单晶的制备,系统阐述焰熔法、提拉法、光浮区法、导模法、布里奇曼法等氧化镓单晶制备方法的国内外研究进展,通过对比不同方法制备氧化镓单晶的晶体生长速度、晶体尺寸和内部缺陷等,分析不同制备方法的优缺点,指出大尺寸低缺陷氧化镓单晶制备方法的未来发展趋势;针对硬度高、脆性大、各向异性大、极易解理破碎的氧化镓晶片的超精密加工技术,详细介绍国内外在超精密加工氧化镓晶片的表面材料去除机理、亚表面损伤产生机理与演变规律,以及氧化镓晶片超精密磨削、研磨和抛光工艺等方面的研究进展,分析氧化镓晶片在加工过程中极易解理破碎的原因和目前采用游离磨料研磨工艺加工氧化镓晶片的局限性,提出未来实现大尺寸氧化镓晶片高效率高表面质量加工的工艺方法。分析表明,在氧化镓单晶制备方面,导模法将是未来批量化制备大尺寸低缺陷氧化镓单晶的最佳方法,但生长过程中气氛的选择与调控、不同缺陷的产生机理与抑制方法以及p型氧化镓单晶的掺杂方法等问题亟需解决。在氧化镓晶片超精密加工方面,基于工件旋转磨削原理的金刚石砂轮超精密磨削技术将是实现大尺寸氧化镓晶片高效高表面质量加工的有效方法,但氧化镓单晶延性域去除和解理破碎的临界磨削条件、表面质量和加工效率约束下的砂轮参数和磨削参数的选择等问题还亟待系统研究,才能为氧化镓晶片的超精密磨削加工提供理论指导。
Gallium oxide(β-Ga2O3) is recognized to be the next generation semiconductor material after silicon carbide(SiC) and gallium nitride(Ga N), and can be used for making high-performance semiconductor devices, including ultra-high voltage power devices, deep ultraviolet optoelectronic devices and high-brightness LED, etc. However, the grown methods of β-Ga2O3 ingots with large-size and defect-free and the ultra-precision machining technologies of β-Ga2O3 wafers with high surface integrity are one of the bottleneck problems for the mass production of β-Ga2O3 based semiconductor devices for increasing applications in electronics industries. For the preparation methods of β-Ga2O3 single crystals easily generated crystal defects during growth, the recent advances in β-Ga2O3 ingot growth methods including Verneuil method, Czochralski method, optical floating zone method, edge-defined film-fed growth method, and Bridgman growth method are review. The five growth methods are also compared in terms of growth rate, crystal size and crystallographic defects, and the future direction of preparation method of β-Ga2O3 monocrystals with lager size and fewer defects is given. For the ultra-precision machining technologies of difficult-to-machine β-Ga2O3 wafers due to its characteristics of high hardness, high brittleness, strong anisotropy and easy cleavage, the recent developments in material removal mechanism and subsurface damage characteristics of β-Ga2O3 wafer during machining and its machining processes including grinding, lapping and polishing are presented. The fracture characteristic and mechanism β-Ga2O3 wafer during machining is analyzed. The limitations of loose abrasive lapping being employed for machining β-Ga2O3 wafers are reviewed, and the further trend of machining technology of β-Ga2O3 wafers with lager size and high surface integrity is given. The analysis shows that edge-defined film-fed growth method is the most appropriate method for mass production of lager size and high quality β-Ga2O3 single crystals, but some questions, such as the selection and control of growth atmosphere, formation mechanism and suppression of crystallographic defects, and P-type doping method of β-Ga2O3 single crystals, should be systematically investigated and answered in future work. Diamond grinding using workpiece rotational face-grinding mode is the best method for cost-effective machining large size β-Ga2O3 wafers to achieve high surface integrity, however, future works including the critical grinding conditions of ductile removal and effective removal, grinding wheel and process parameters selection method constrained by surface quality and machining efficiency should be done for providing theoretical guidance for the ultra-precision grinding of β-Ga2O3 wafers.
作者
高尚
李洪钢
康仁科
何宜伟
朱祥龙
GAO Shang;LI Honggang;KANG Renke;HE Yiwei;ZHU Xianglong(Key Laboratory for Precision and Non-traditional Machining Technology of Ministry of Education,Dalian University of Technology,Dalian 116024)
出处
《机械工程学报》
EI
CAS
CSCD
北大核心
2021年第9期213-232,共20页
Journal of Mechanical Engineering
基金
国家自然科学基金(51975091,51735004,55991372)
国家重点研发计划(2018YFB1201804-1)
中央高校基本科研业务费(DUT19LAB15)
江苏省精密与微细制造技术重点实验室开放基金资助项目。
关键词
半导体材料
氧化镓单晶
晶体生长
超精密加工
semiconductor material
β-Ga2O3 single crystal
crystal growth
ultra-precision machining
