多晶金刚石对硅基氮化镓材料的影响  

Influence of polycrystalline diamond on silicon-based GaN material

作　　者：刘庆彬[1] 蔚翠[1] 郭建超[1] 马孟宇 何泽召[1] 周闯杰 高学栋 余浩 冯志红[1] Liu Qing-Bin;Yu Cui;Guo Jian-Chao;Ma Meng-Yu;He Ze-Zhao;Zhou Chuang-Jie;Gao Xue-Dong;Yu Hao;Feng Zhi-Hong(National Key Laboratory of Solid-State Microwave Devices and Circuits,Hebei Semiconductor Research Institute,Shijiazhuang 050051,China)

机构地区：[1]河北半导体研究所,固态微波器件与电路全国重点实验室,石家庄050051

出　　处：《物理学报》2023年第9期339-346,共8页Acta Physica Sinica

基　　金：国家重点研发计划(批准号:2018YFE0125900);国家重点科学技术研究专项(批准号:2009ZYHW0015)资助的课题。

摘　　要：氮化镓(GaN)器件的自热问题是目前限制其性能的关键因素,在GaN材料上直接生长多晶金刚石改善器件的自热问题成为研究的热点,多晶金刚石距离GaN器件工作有源区近,散热效率高,但多晶金刚石和GaN材料热失配可能会导致GaN电特性衰退.本文采用微波等离子体化学气相沉积法,在2 in (1 in=2.54 cm)Si基GaN材料上生长多晶金刚石.测试结果显示,多晶金刚石整体均匀一致,生长金刚石厚度为9—81 μm,随着多晶金刚石厚度的增大, GaN (002)衍射峰半高宽增量和电性能衰退逐渐增大.通过激光切割和酸法腐蚀,将Si基GaN材料从多晶金刚石上完整地剥离下来.测试结果表明:金刚石高温生长过程中,氢原子对氮化硅外延层缺陷位置有刻蚀作用形成孔洞区域,刻蚀深度可达本征GaN层;在降温过程,孔洞周围形成裂纹区域.剥离下来的Si基GaN材料拉曼特征峰峰位, XRD的(002)衍射峰半高宽以及电性能均恢复到本征状态,说明多晶金刚石与Si基GaN热失配产生应力,引起GaN晶格畸变,导致GaN材料电特性衰退,这种变化具有可恢复性,而非破坏性.Self-heating has become a limited factor for the performance improvement of GaN electronics.Growing polycrystalline diamond directly on GaN material to solve the heating problem of GaN devices has become one of the research highlights.Polycrystalline diamond on Si-based GaN material has the advantages of being close to the channel region and high heat dissipation efficiency.However,there is a problem that the thermal expansion mismatch between polycrystalline diamond and GaN material leads to the deterioration of electrical characteristics of GaN.In this work,we adopt microwave plasma chemical vapor deposition(MPCVD)method to grow polycrystalline diamond on 2-inch Si-based GaN material.The test results show that the polycrystalline diamond is uniform as a whole.The average thickness is in the range of 9–81μm.With the thickness of polycrystalline diamond increasing,the XRD(002)diffraction peak FWHM increment and mobility loss gradually increase for the Si-based GaN material.Through laser cutting and acid etching,the Si-based GaN material is successfully stripped from the polycrystalline diamond.It is found that during the process of diamond growth at high temperature,hydrogen atoms etch the defect positions of the silicon nitride epitaxial layer,forming a hole area in the GaN,and the etching depth can reach the intrinsic GaN layer.During the process of cooling,a crack area is formed around the hole area.Raman characteristic peaks,full widths at half maximum of XRD(002)diffraction peaks,and electrical properties of the stripped Si-based GaN materials are all returned to their intrinsic states.The above results show that the thermal expansion mismatch between polycrystalline diamond and Si-based GaN introduces stress into GaN,which leads to lattice distortion of GaN lattice and the degradation of electrical property of GaN material.The degradation of GaN material is recoverable,but not destructive.

关 键 词：多晶金刚石 氮化镓 微波等离子体化学气相沉积法 电性能 

分 类 号：TN386[电子电信—物理电子学] TQ133.51[化学工程—无机化工]