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过程中中性自由基反应的动力学，我们对它们在固体表面上的反应进行了现场诊断。作为第一步，我们建立了由射频和微波放电驱动的合适的自由基源。我们还建立了利用激光诱导荧光光谱(LIF)、腔内激光吸收光谱(ICLAS)等高灵敏的方法来测量这些来源的流出自由基的密度和通量。在成功检测到的自由基中，有Si、SiH、SiH_2等含硅自由基和H、O、N等原子自由基。首先，研究了氢化非晶硅(a-Si：H)沉积过程中SiH_n(n=0-2)的反应。通过比较这些自由基的特征入射通量和所沉积薄膜的光电性质，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结果一致。其次，利用氧自由基源研究了硅片表面低温氧化的机理，其中氧化的增强作用与氧原子的流量和电子激发氧分子的流量有关。

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.