Analysis of Chemical Reactions for Control of Si-Network-from Amorphous to Single Crystal-

为实现对硅网生长表面化学反应的控制，采用非平衡工艺制备了非晶态、多晶硅和外延硅结构的硅薄膜，其低温温度可达300ﾟC。采用椭偏仪和有效介质近似模拟相结合的方法对薄膜表面进行了原位观察，提出了一种名为“化学退火法”的新技术，即用MUW等离子体产生的氢原子交替处理硅烷射频辉光沉积10A厚的超薄薄膜。由于生长表面的结构弛豫促进了a-Si：H薄膜的生长，成功地制备出了更坚硬稳定的a-Si：H薄膜。此外，我们还成功地利用ECR氢等离子体制备了用于SiCl2H2光浸渍的高度稳定的a-Si：H。SiFnHm(n+m(n+m)SY.ltoreq.()3)给出的自由基是制备有序结构硅网络结构的有希望的前驱体。用氟化前驱体在300ﾟC或更低的温度下，在c-Si(100)衬底上生长了外延硅。此外，利用该前驱体在玻璃衬底上交替沉积了100A厚的薄层，并用氢原子流对其表面进行处理，在玻璃衬底上生长了高质量的多晶硅薄膜。(Leyer-by-Layr技术)由非晶态到晶态的相变是由氢的撞击引起的，氢被认为是导致晶粒生长的原因。建立了高质量的电学和光学性能。

A systematic study was performed to realize the control of chemical reactions at the growing surface of Si-network for the aim of fabrication of Si thin films at low temperature as low as 300ﾟC with the structures, viz., amorphous, poly-(or muc-)Si and epi-Si by adopting non-equilibrium processing. An ellipsometry together with simulation by Effective Medium Approximation was employed as the in situ observation of the surface.A novel technique termed "Chemical Annealing" was proposed, where the deposition of very thin film of 10 A thick by RF glow of silane was alternately repeated with the treatment with atomic hydrogen generated by muW plasma. a-Si : H thin films with more rigid and stable network were successfully made by this technique due to promotion of the structural relaxation at the growing surface. In addition, we succeeded to fabricate highly stabilized a-Si : H for light soaking from SiCl_2H_2 by means of ECR hydrogen plasma. Strong chemical interaction between bydrogen and chlorine at the surface was responsible for the relaxation.Radicals given by SiFnHm (n+m(〕SY.ltoreq.〔)3) were promising precursors to fabricate Si-network with ordered structures. Epi-Si was grown on c-Si(100) from the fluorinated precursors at 300ﾟC or lower. In addition, high quality poly-Si films were grown on glass substrate using this precursors by repeating alternately the deposition of thin layr of 100 A thick and the treatment of the surface with flow of atomic hydrogen. (Leyer-by-Layr Technique) The phase transition from amorphous to crystalline was induced by impingement of hydrogen, which is considered to be responsible for the grain growth. High qualities in the electric and optical properties were established.