INTERACTION OF FREE-RADICALS WITH SOLID SURFACES AS STUDIED BY FLUORESCENCE-IMAGING METHOD WITH CROSSED BEAMS

为了了解等离子体和光激发材料加工中中性自由基反应的动力学，我们对其在固体表面上的反应进行了原位诊断。作为第一步，我们建立了合适的自由基源驱动的RF和MW放电。利用激光诱导荧光光谱（LIF）、腔内激光吸收光谱（ICLAS）等技术，建立了高灵敏度的自由基密度和通量测量方法，成功地测量了Si、SiH、SiH_2等含硅自由基和H、O、N等原子自由基。本文研究了氢化非晶硅（a-Si：H）淀积过程中SiH_n（n=0-2）的反应。通过比较这些自由基的入射通量和薄膜的光电性能，讨论了沉积过程中的反应机理。所得结果也与我们提出的表面反应模型的计算机模拟一致。其次，利用氧自由基源研究了硅片表面的低温氧化机理，认为氧化的增强与氧原子和电子激发态氧分子的通量有关。

In order to understand the kinetics of neutral radical reactions in plasma-and photo-excited material processing, we performed in-situ diagnostics of their reactions on the solid surfaces. As the first step, we built suitable radical sources driven by RF- and MW-discharges. We established also highly-sensitive methods to measure the densities and fluxes of effused radicals from these sources by using laser induced fluorescence spectroscopy (LIF), intra-cavity laser absorption spectroscopy (ICLAS) and so on. Among the successfully detected radicals are Si-containing radicals such as Si, SiH and SiH_2 and atomic radicals such as H, O and N.Firstly, the reactions of SiH_n(n=0-2) have been studied in the deposition of hydrogenated amorphous silicon (a-Si:H). From a comparison of characterized incident flux of these radicals and the measured optical and electrical proper-ties of the deposited films the reaction mechanisms involved in the deposition have been discussed. The obtained result is also consistent with a computer simulation of our proposed surface reaction model. Secondly, the mechanism of low temperature oxidation of silicon wafer surface has been studied using an oxygen radical source, in which the enhancement of oxidation has been correlated with the flux of oxygen atoms and electronically excited oxygen molecules.