High Voltage SiC Power Transistor having High Quality Gate Insulator Formed by Microwave Excited Plasma

利用微波激励高密度等离子体制备的SiO_2薄膜，通过去除碳原子，在低于1,000[℃]的工艺温度下实现了高质量的栅氧化层。微波激励的高密度等离子体可以产生O^*自由基，从而在每个Si表面形成具有低固定电荷密度和低Inire陷阱密度的高质量的SiO_2薄膜，如(100)，(110)，(111)，以及低温多晶硅(&lt；500[℃])。然而，仅在400[℃]时的O^*氧化不能形成高质量的氧化物，它含有大量的10^&lt；19&gt；[atmos/cmt；3]的碳原子和10^&lt；12&gt；[cm^&lt；-2&gt；]的高固定电荷密度。在1000[℃]下进行氮气退火，可使碳含量和固定电荷密度降低一个数量级。采用双喷淋板结构的微波激励高密度等离子体系统，在CVD沉积SiO_2薄膜后，可以得到所需厚度的高SiO_2薄膜。另一方面，结合化学气相沉积多晶硅和后续的O^*氧化可以在400[℃]的温度下在碳化硅表面形成高质量的SiO_2薄膜。在这种方法中，SiO_2膜中的界面陷阱和固定电荷密度也比在碳化硅表面直接氧化的SiO_2膜降低了一个数量级。用射频-直流耦合溅射系统在Si(100)表面沉积了高质量的SiO_2薄膜，沉积温度为950[℃]时，经氮气退火后，在低于1000[℃]的工艺温度下，可以在Si(100)表面形成高质量的SiO_2薄膜。

High quality gate oxides are realized in the process temperature less than 1000[℃] by removal of carbon atoms from SiO_2 films formed by microwave excited high-density plasma. The microwave excited high-density plasma can generate the O^* radical, as a result, it can form the high quality SiO_2 films which have low fixed charge density and low int ire trap density on every Si surface such as (100), (110), (111), and polycrystalline Si at low temperature (<500[℃]). However, only O^* oxidation at 400[℃] cannot form the high quality oxides, which contain many carbon atoms of 10^<19> [atmos/cm^3] and high fixed charge density of 10^<12>[cm^<-2>]. The carbon content and the fixed charge density can be reduced one order of magnitude by N_2 annealing at 1000[℃]. The high SiO_2 films of desired film thickness can be formed by following CVD SiO_2 deposition using the dual shower plate structure microwave excited high-density plasma system. On the other hand combination of CVD Poly-Si and following O^* oxidation can form the high quality SiO_2 films on SiC surface at 400[℃]. In this method, the interface trap and fixed charge densities in the SiO_2 film can also reduced one order of magnitude compared with SiO_2 films directly oxidized by O^* oxidation on SiC surface. These indicate that the high quality SiO_2 films can be formed on SiC surface at low temperature less than 1000[℃].SiC films are deposited on Si(100) surface at 400[℃] using by RF-DC coupled sputter system The crystal of SiC(111) are appeared by N_2 annealing at 950[℃] after the deposition This suggests that the SIC crystal can be formed at the process temperature less than 1000[℃].