N型4H-SiC同质外延生长

Nitrogen doped 4H-SiC homoepitaxial layers grown by CVD

利用水平式低压热壁CVD(LP-HW-CVD)生长系统,台阶控制生长和衬底旋转等优化技术,在偏晶向的4H-SiCSi(0001)晶面衬底上进行4H-SiC同质外延生长,生长温度和压力分别为1550℃和104Pa,用高纯N2作为n型掺杂剂的4H-SiC原位掺杂技术,生长速率控制在5μm/h左右.采用扫描电镜(SEM)、原子力显微镜(AFM),傅里叶变换红外光谱(FTIR)和Hg/4H-SiC肖特基结构对同质外延表面形貌、厚度、掺杂浓度以及均匀性进行了测试.实验结果表明,4H-SiC同质外延在表面无明显缺陷,厚度均匀性1.74%,1.99%和1.32%(σ/mean),掺杂浓度均匀性为3.37%,2.39%和2.01%.同种工艺条件下,样品间的厚度和掺杂浓度误差为1.54%和3.63%,有很好的工艺可靠性.

Homoepitaxial growth of gH-SiC on off-oriented Si-face （0001） 4H-SiC substrates is performed at 1550℃, under the pressure of 100 mbar using the mbar step-controlled technique with rotation in the horizontal low-pressure hot-wall CVD （ LP-HW- CVD） system to obtain high quality 4H-SiC epilayers. The surface morphology, structure and optical properties of the epilayers are characterized by SEM, AFM, FTIR and C-V measurement. The 4H-SiC epitaxial layer has a good crystalline structure and mirror-like surface with few surface defects. N type 4H-SiC epilayers are obtained by in-situ doping of N2 .The uniformities of thickness are 1.74 %, 1.99 %, and 1.32 %, and the uniformities of doping concentration are tested to be 3.37 %, 2.39 %, and 2.01%, respectively. The deviations in thickness and concentration between different samples are 1.54% and 3.63% under the same processing conditions, which shows that the process is repeatable and reliable.