温度和氯源对大功率IGBT栅氧工艺的影响

Effect of Oxidation Temperature and Chlorine Source on the Gate Oxidation Process for High Power IGBT

采用C-V测试技术对大功率IGBT栅氧制备工艺中常用的两种栅氧生长方法——干氧和湿氧进行了研究,重点分析了氧化温度和氯源对栅氧化层工艺质量的影响,特别是对栅氧化层固定电荷和界面陷阱电荷的影响。研究结果表明：在1 000-1 150℃温度区间,非掺氯干氧通过高温氮气退火处理可获得好的固定电荷密度（Nss）特性,氧化温度对N_（ss）影响很小,但对于掺氯干氧,当氧化温度超过1 050℃时,N_（ss）会明显增大;通过450℃氢退火处理,可将干氧的界面陷阱电荷密度（D_（it））控制在较低范围内,氧化温度和氯源对干氧的D_（it）影响不明显;在850-1 000℃温度区间,湿氧无法通过高温氮气退火和450℃氢退火处理而同时获得好的Nss和Dit特性,氧化温度和氯源对N_（ss）和D_（it_的影响较干氧的明显。

Two main gate oxidation processes of high power IGBT based on dry oxidation and wet oxidation were studied by capacitance-voltage（C-V） method. Effect of oxidation temperature and chlorine source on the quality of gate oxidation, especially on fixed oxide charge（Nss） and interface trapped charge（D_（it））, was investigated in detail. Experimental results show, for dry oxide grown in 1 000℃ - 1 150℃ without chlorine source, lower fixed oxide charge was obtained by high-temperature nitrogen annealing and the effect of oxidation temperature on Nss could be ignored nearly. However, chlorine obviously increased Nss of dry oxide when oxidation temperature increased above 1 050℃. Interface trapped charge of dry oxide was easy to be controlled at low level by 450℃ hydrogen-containing postmetal anneal, which clearly decreased the effect of oxidation temperature and chlorine source on D_（it）. For wet oxide grown in 850 -1 000 ℃, it was difficult to obtain lower N_（ss） and D_（it） by both high-temperature nitrogen annealing and 450 ℃ hydrogen-containing post-metal anneal. Compared to dry oxidation, wet oxidation significantly increased the dependence of N_（ss） and D_（it） on oxidation temperature and chlorine source.