SiC晶圆背面激光退火工艺研究

Study on Laser Annealing Process of SiC Wafer Backside

降低芯片背面金属-半导体欧姆接触电阻是有效提高器件性能的方式之一。采用650 V SiC肖特基势垒二极管(SBD)工艺,使用波长355 nm不同能量的脉冲激光进行退火实验,利用X射线衍射(XRD)和探针台对晶圆背面镍硅合金进行测量分析,得出最佳能量为3.6 J/cm^(2)。退火后采用扫描电子显微镜(SEM)观察晶圆背面碳团簇,针对背面的碳团簇问题,在Ar;气氛下对晶圆进行了表面处理,使用SEM和探针台分别对两组样品的表面形貌和电压-电流特性进行了对比分析。实验结果表明,通过表面处理可以有效降低表面的碳含量,并且使器件正向压降均值降低了6%,利用圆形传输线模型(CTLM)测得芯片的比导通电阻为9.7×10^(-6)Ω·cm^(2)。器件性能和均匀性都得到提高。

Reducing the metal-semiconductor ohmic contact resistance on the backside of the chip is one of the effective ways to improve the performance of the device.A 650 V SiC Schottky barrier diode(SBD)process was used for annealing experiments with different energies of 355 nm pulsed laser.The nickel silicon alloy on the wafer backside was measured and analyzed by X-ray diffraction(XRD)and probe station,and the best energy of 3.6 J/cm^(2) was obtained.The carbon clusters on the wafer backside were observed by scanning electron microscope(SEM)after annealing.For the problem of the carbon clusters on the backside,the wafer surface treatment of carbon clusters was carried out in Ar;atmosphere.SEM and probe station were used to compare the surface morphology and voltage-current characteristics of the two groups of samples.The experimental results show that surface treatment can effectively reduce the carbon content on the surface and reduce the average forward voltage drop of the device by 6%.The specific on-resistance of the chip measured by the circular transmission line model(CTLM)is 9.7×10^(-6)Ω·cm^(2).The performance and uniformity of the device are improved.