摘要
采用新电极结构的PECVD技术 ,在高功率密度、高氢稀释比、低温、偏压及低反应气压的条件下 ,在SiO2 玻璃表面形成双等离子流 ,增加了SiO2 表面SiC的成核几率 ,增强成核作用 ,形成纳米晶。采用高H2 等离子体刻蚀弱的、扭曲的、非晶Si-C及Si-Si和Si-H等键时 ,由于H等离子体对纳米SiC晶粒与非晶态键的差异刻蚀作用 ,产生自组织生长 ,发生晶化。Raman光谱和透射电子衍射 (TEM )的测试结果表明 ,纳米晶SiC是 4H -SiC多型结构。实验结果指出 ,SiC纳米晶的形成必须经过偏压预处理成核 ,并且其晶化存在一个功率密度阈值 ;当低于这一功率密度阈值时 ,晶化消失 ;当超过这一阈值时 ,纳米晶含量随功率密度的提高而增加 ,晶粒尺寸加大。电子显微照片表明晶粒尺寸为 1 0～ 2 8nm ,形状为微柱体。随着晶化作用的加强 ,电导率增加 。
A PECVD technique with new electrode construction is designed.We use it to deposit nanocrystalline silicon carbide films(nc SiC) with high power density, high hydrogen dilution ratio,bias pretreatment,bias control and low reaction pressure at low temperature. New structure of PECVD can produce nc SiC films,which are formed by two plasma flows on the surface of SiO 2 glass to increase the probability of producing SiC cores.When etching weakly and distorted amorphous Si Si,C C and Si H bonding by high H 2 plasma the differential etch function of H plasma to nanocrystalline SiC and amorphous SiC makes the nanocrystalline SiC self-organized growth, hence the nc SiC films were crystallized. Raman spectra and TEM images indicated that the nanocrystalline SiC films are four hexagonal polytype of SiC.The experimental results,showed that the bias pretreatment and nucleation are necessary for the nc SiC formation and there exists a threshold of power density for its crystallization.When the power density is less than the threshold the crystallization disappears and when the power density is larger than the threshold the nc SiC content in the film will increase with the increase of power density and the nc SiC size will become larger.TEM indicated that the mean size of nc SiC is 10～28nm,and the shapes of nc SiC are microcolumnar. The enhancement of crystallization will result in an increase of conductivity, which is caused by the permeability resulted in nanocrystalline nc SiC in films.
出处
《微细加工技术》
2002年第1期30-35,共6页
Microfabrication Technology
基金
原国家教委博士学科点基金资助项目(J9780 4 73)
湖北省教育厅重大项目 (2 0 0 0Z0 0 4 )
关键词
4H-SIC
晶化
纳米薄膜
nanoelectronics
four hexagonal polytype silicon carbide
PECVD
nanostructure film
self organized growth
