低温非平衡甲烷等离子体发射光谱诊断

【作者】 罗利霞；

【导师】 孙卫国；

【作者基本信息】 四川大学 ， 原子与分子物理， 2007， 硕士

【摘要】 近年来，低压等离子体化学气相沉积技术的研究发展很快，在包括各种薄膜等新型功能材料的制备研究方面取得了令人瞩目的成就。然而目前对等离子体化学气相沉积（PCVD）过程中薄膜的生长机理还缺乏清楚的理解，发展沉积过程中的等离子体的原位诊断显得尤为重要。对等离子体过程诊断的方法有许多，其中发射光谱法（OES）是一种非常好的诊断手段——一种比较简单的非扰动方法。本文就是利用光学发射谱技术研究了CH₄／He、CH₄／H₂气体螺旋波（HWP）放电等离子体内一些活性粒子的光学发射特征、并对其进行了原位测量。重点研究了在CH₄／He、CH₄／H₂这两种体系下它们放电等离子体中基团的分布；分析了不同基团的相对密度随宏观放电条件（射频输入功率、放电气压）的变化规律。结果表明，在两种体系中，甲烷气体放电HWP等离子体空间中存在H（H_α（656.3nm）、H_β（486.1nm）、H_γ（434.1nm））、H₂和CH（431nm）基团等，需要特别指出的是，在CH₄放电等离子体的发射光谱中只出现了H、H₂和CH基团的特征发射谱线，但这并不意味着等离子体中只存在这些基团；在CH₄／He体系下，随射频功率的增加，H_α、H_β、H_γ以及CH相对强度变化的总体趋势都是先增加而后减小的，当工作气压增加时，H_α、H_β以及H_γ的相对强度变化也是呈现先增大而后减小的，但CH基团的相对强度是逐渐减小的；在CH₄／H₂体系下，随着射频功率的增大H_α、H_β、H_γ以及CH基团的相对强度都随着增加，而当放电气压变化时它们都呈现先增大而后减小的趋势。这些结果为等离子体沉积各种薄膜过程的理解及制备工艺参数的调整提供了重要的物理依据和基础数据。更多还原

【Abstract】 In recent decades, great achievements have been acquired in the preparation of new function materials including various films with the development of low pressure plasma chemical vapor deposition. However, the growth mechanism of some films in the process of plasma chemical vapor deposition （PCVD） remains unclear. At present, the development of the plasma diagnosis in situ in the process of the deposition is of great importance. There are many methods used for the plasma process diagnosis, wherein optical emission spectroscopy （OES） is a powerful diagnostic tool—a simple method without disturbing the reactions. In this thesis, we studied the distributions of different radicals in the CH₄/He, CH₄/H₂ plasmas and the variations of the relative intensities of these radicals with different experimental conditions such as the input rf power and the gas pressure.It was showed that the emission lines of H, H₂ and CH radicals had been identified in the methane plasma in the two systems. In the CH₄/He system, the intensities of these active species are initially increased and then decreased as increasing the input rf power, and as the gas pressure increases, the intensity of the CH radical is always decreased, the intensities of H_α, H_βand H_γspecies are initially increased and then decreased; In the CH₄/H₂ system, the relative intensities of H_α, H_β, H_γand CH radicals are increased as increasing input rf power, and the relative intensities of all these radicals are initially increased and then decreased as increasing of the discharge pressure. These experimental results offer the basic data for understanding the process of hydrocarbon thin film deposition.更多还原