Low temperature growth of 3C-SiC crystal by hydrogen radical assisted plasma enhanced chemical vapor deposition

本项目的目标是利用射频等离子体产生的氢自由基实现3C-碳化硅的低温生长及其在硅衬底上的外延生长。1997年，以二甲基硅烷和二甲基硅烷为源气体进行了三极管等离子体CVD法和混合等离子体CVD法生长晶体的实验结果表明，以二甲基硅烷为源气体的三极管等离子体CVD法是有效的，在600ﾟC下生长晶体是可能的。在较低的等离子体空间势和较低的电子温度(~lt；1 eV)条件下，实现了低温下的碳化硅晶体生长。通过抑制等离子体空间势的高频振动，减少鞘层区氢离子的积累，进一步提高了薄膜的结晶度。在10 0 0ﾟC下也成功地在Si(10 0)和(111)衬底上外延生长了碳化硅薄膜.用三极管等离子体化学气相沉积方法生长的碳化硅薄膜的表面形貌比热化学气相沉积方法更令人满意.1998年，为了生长碳化硅外延薄膜，采用了抽气率高的涡轮分子泵来控制氢气稀释比和反应压力的条件.实验结果表明，在反应压力为0，3Torr，氢气稀释率较高(&gt；200)的条件下，获得了结晶度最好的高度取向的碳化硅外延薄膜。通过改变氢稀释比，碳化硅在Si(111)晶面上的残余应力可以从压缩应力变为拉伸应力。通过控制氢的稀释比，可以在硅衬底上获得低残余应力的碳化硅外延薄膜。

The objective of this project is to realize the low temperature growth of 3C-SiC and epitaxial growth of it on Si substrates utilizing the hydrogen radicals generated by rf plasma.In 1997, as a result of the experiments of crystal growth by triode plasma CVD method and by hybrid plasma CVD method allow temperature (<1000ﾟC) using dimethyichiorosilane and dimethylsilane as source gases, it became clear that the triode plasma CVD method using dimethylsilane was effective and the crystal growth at 600ﾟCwas possible utilizing the method. The crystal growth of SiC at the low temperature was realized under the conditions of low plasma space potential and low electron temperature (<1eV) in the vicinity of the substrate surface. Reducing the hydrogen ion acceralation at sheath region by the suppression of the rf vibration of plasma space potential , the crystallinity of SiC films was further improved. Epitaxial growth on Si(100) and (111) was also successful at 1000ﾟC.Using the triode plasma CVD method, the surface morphplogy of SiC films was more satisfactory than that grown by thermal CVD method.In 1998, the conditions of the dilution ratio of source gas by hydrogen and the reaction pressure were extensively controlled using the turbo molecular pump, which has high evacuation rate, for the growth of epitaxial SiC films. As a result of this experiment, highly oriented SiC epitaxial films with best crystallinity were obtained at reaction pressure of 0,3 Torr and at high dilution rate of hydrogen (>200). By changing the hydrogen dilution ratio, the residual stress of SiC on Si (111) was able to vary from coinpresive to tensile. By control the hydrogen dilution ratio, SiC epitaxial film on Si substrates with low residual stress was able to be obtained.