Diagnostic and Control of Silane Plasmas by Newlv Developed Radical Measurement Technique

从工业角度来看，降低硅膜的沉积温度是必要的，因为工艺温度有时会限制衬底材料和工艺吞吐量。本项目主要有两个目的，一是开发新的自由基检测技术用于硅烷等离子体的诊断和控制，二是利用电感耦合硅烷等离子体（硅烷ICP）生产高质量的氢化非晶硅和/或多晶硅。作为硅烷等离子体中SiH3自由基的一种新的诊断技术，我们开发了一种能够同时检测硅烷等离子体中SiH3自由基和粒子的紫外透射光谱技术。这个强大的工具是非常简单和容易适用于大多数等离子体反应器。我们还成功地在相对较低的衬底温度（40和250）下沉积了高光导电性的氢化非晶硅和多晶硅。研究发现，在高等离子体密度和低压等离子体条件下，沉积了高质量的薄膜。这些条件与电容耦合等离子体的条件完全不同，因为在电容耦合等离子体中，高射频功率或低压总是会降低薄膜的性能。等离子体质谱分析显示，硅烷分子在ICP中几乎完全消失，与中性自由基通量相比，向底物的离子通量占主导地位。

From a industrial point of view, lowering deposition temperature of silicon films are needed because process temperature sometimes limits substrate materials and process throughput. This project has two main purposes, i.e., firstly to develop new radical detection technique for diagnostic and control of silane plasma, and secondly, to produce high quality hydrogenated amorphous silicon and/or polycrystalline silicon by using a inductively coupled silane plasma (silane ICP).1.As a new diagnostic technique of SiH3 radical in silane plasma, we have developed ultra-violet transmission spectroscopy, which can detect SiH3 radicals and particulates in a silane plasma at the same time. This powerful tool is very simple and easy to apply for most of plasma reactors.2.We also succeeded in depositing high photoconductivity hydrogenated amorphous silicon and polycrystalline silicon at relatively low substrate temperatures of 40 and 250ﾟC,respectively. It is found that high quality films are deposited at high plasma density and low pressure plasma conditions. These conditions are quite different from those for capacitively coupled plasmas, because high rf powers or low pressures always degrades film properties in capacitively coupled plasmas. Plasma diagnostic by mass spectrometry revealed that silane molecules are almost completely depleted in the ICP and ion flux to the substrate is dominant compared with neutral radical flux.