4H-SiC高速同质外延研究

研究了生长温度为1400℃时4H-SiC同质外延膜的生长速率、表面形貌及缺陷. 拉曼表征并结合KOH腐蚀表明外延膜中未出现3C-SiC多晶, 为单一的4H-SiC晶型. 通过KOH腐蚀发现, 低生长速率和高C/Si比有利于衬底表面的基平面位错(BPDs)转变成露头刃位错(TEDs). 在高生长速率下, 外延膜的表面三角形缺陷和位错密度会显著增加. 通过引入界面层, 可以实现生长初期的平滑过渡, 极大地降低高生长速率下外延膜的缺陷密度.

High-speed Homoepitaxial Growth of 4H-SiC

Homoepitaxial growth of 4H-SiC at 1400℃ was explored.The growth rate,surface morphology and defects of the epi-layers were studied.Raman characterization combined with KOH etching indicated that the epi-layers were 4H-SiC single crystal without 3C-SiC polycrystalline.In addition,low growth rate and high C/Si ratio were beneficial to convert the basal plane dislocations(BPDs) in substrate surface to threading edge dislocations(TEDs) at the sub-epi interface.Furthermore,the low growth rate was also favorable to reduce the defects generated during the growth process.With the growth rate increasing,the surface triangle defects and dislocations of the epilayers significantly increased.Most of these defects and dislocations were considered to be generated at the sub-epi interface at the beginning of the growth.By optimizing the interface layer at initial stage,a smooth transition from surface etching to epi-layer deposition can be achieved while the surface morphological defects and crystal defects are greatly reduced at high growth rate.