Development of large-diameter RF plasmas under surface magnetic field

为了产生用于材料加工的高密度、大直径和低压等离子体，对等离子体的产生、诊断和控制进行了广泛的研究和开发。本研究的主要结果如下：1.高密度等离子体的产生通过将电感式射频天线插入表面磁场覆盖的真空容器中，在低压下产生了大直径的高密度等离子体。从等离子体的天线的静电耦合被证明是由一个法拉第屏蔽抑制。另一方面，研究了螺旋等离子体对射频功率的吸收机制。在低磁场（<100 G）和低功率（<1 kW）条件下，RF功率通过天线近场而不是螺旋波场沉积到等离子体中。2.高密度等离子体的诊断、控制和应用详细的诊断表明，高电子密度大大改变了自由基的组成，从而降低了蚀刻选择性。本文提出了两种解决这一问题的方法：一种是壁加热法（100-200 ℃），另一种是脉冲放电法（持续时间~ 10 μ s），此外，我们还发展了用等离子体振荡法测量电子密度，用偏置光探针法测量电子能量分布函数，用紫外吸收光谱法测量SiH_3自由基和微粒的新技术。

The research and development on plasma production, diagnostics and control have been extentsively performed in order to produce a high-density, large-diameter and low-pressure plasma for materials processing. The results obtained in this study are summarized below :1.High-Density Plasma ProductionA large-diameter high-density plasma at low pressures was generated by inserting an inductive RF antenna into a vacuum vessel which is covered with surface magnetic fields. Electrostatic coupling of the antenna from plasma was shown to be suppressed by a Faraday shield. On the other hand, mechanisms of RF power absorption in a helicon plasm were investigated. Under the conditions of low magnetic fields (<100 G) and low power (<1 kW) , the RF power turned out to be deposited into a plasma via antenna nearfields rather than helicon wave fields.2.Diagnosticcs, Control and Applications of High-Density PlasmasThe detaild dignostics showed that a high electron density considerably modifies the radical composition, thus degrading an etch selectivity. Two methods to solve this problem were developed : one is a vessel wall heating (100-200ﾟC) and the other is a pulsed discharge (duration -10mus) .In addition, we developed new techniques for measuring electron density by a plasma oscillation method, electron energy distribution functi on by a biased optical probe method, and SiH_3 radical and particulates by ultravioret absorption spectroscopy.