Selective Reaction Control of CVD Process by a New Discharge Technique

本文对超短高压脉冲放电等离子体进行了研究，重点研究了超短高压脉冲放电等离子体的结构控制，为等离子体CVD过程中自由基反应的主动控制提供了一种很有前途的技术。超短高压脉冲放电等离子体在极高的外加电压高达几千伏的情况下，成功地建立了稳定、均匀的等离子体，在电极或衬底表面没有任何等离子体的不均匀。阐明了维持超短脉冲等离子体的条件或标准。电流上升到电压上升的滞后时间随着外加电压的减小而增加，如果达到脉冲宽度的值，就不可能引发等离子体。阐明了超短高压脉冲等离子体的一些特殊特性，包括超高功率区的伏安特性、电流上升的滞后时间以及压力和脉冲宽度的影响，以及阴极和阳极之间的径向发射强度分布。高功率超短脉冲等离子体具有清晰的层状结构，在阳极附近有一个类似于已知正柱的发光区，在阴极附近有一个暗空间，这种结构只需通过压力、外加电压和阴阳极之间的距离来很好地控制。应用本研究开发的新技术，可以对等离子体CVD过程中的自由基反应和离子能量进行主动控制。

An ultra-short and high-voltage pulse discharge plasma has been studied focusing on the control of its structure as a promising technology for the active control of radical reactions in the plasma CVD processing, and the following conclusions have been obtained.1. Stable and uniform plasmas have been successfully established by the ultra-short and high-voltage pulse discharge plasma at very high applied voltages up to several kilovolts without any plasma non-uniformity on the electrode or substrate surface.2. The conditions or criteria to sustain the ultra-short pulse plasma have been clarified. The lag time of current rise from that of voltage increases with the decrease of applied voltage and if it reaches the value of pulse width the initiation of plasma becomes impossible.3. Several peculiar features of the ultra-short and high-voltage pulse plasma have been clarified including voltage-current characteristics at very high power regions, lag times of current rise and effects of pressure and pulse width, and radical emission intensity profiles between anode and cathode.4. The high-power and ultra-short pulse plasma has a well-defined stratified structure consisting of a luminous zone similar to a well-known positive column near the anode and a dark space near the cathode and this structure can be well controlled only by the parameters of pressure, applied voltage and distance between anode and cathode.5. Active control of radical reactions and ion energies in the plasma CVD processing could be possible by applying the new technique developed in this study.