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Active Cntrol of Surface Reattion in CVD Orocess by an Ultra-Voltage Pulsed Plasma

超高压脉冲等离子体主动控制CVD工艺中的表面反应

基本信息

批准号：
04452147
负责人：
OKAZAKI Ken
金额：
$ 4.67万
依托单位：
Tokyo Institute of Technology (1993)Toyohashi University of Technology (1992)
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1992
资助国家：
日本
起止时间：
1992 至 1993
项目状态：
已结题

项目摘要

Active control of plasma CVD process focussing on the control of surface reactions has been investigated by use of an ultra-short and high-voltage pulsed discharge plasma. First, formation and sustaining conditions of this kind of pulsed plasma have been clarified. Pulse width should have a value between the lower limit to initiate a discharge and the upper limit to prevent a transition to arcing. Next, using a source gas of methane diluted by hydrogen, which is usually used for a synthesis of diamond, two different types of well-controlled stratified plasma have been realized by changing an applied voltage, pressure and pulse width. One is a transient structure of plasma formation and the other is a quasi-steady structure with a strongly luminous positive column near the anode. Based on the above results, active control of CVD process of diamond formation has been actually performed by superimposing an ultra-short and high-voltage pulsed plasma on the usual DC plasma. It has been found that the unclation density on the substrate surface can be largely enhanced by applying an ultra-short pulsed plasma and that this effect becomes larger for the higher peak voltage, the longer pulse width and lower pressure. This could be due to the increase of supersaturation level of key radical species near the substrate surface through realizing the second type of stratified plasma structure

利用超短脉冲高压放电等离子体，研究了等离子体化学气相沉积过程的主动控制，重点是表面反应的控制。首先，阐明了这种脉冲等离子体的形成和维持条件。脉冲宽度的值应介于引发放电的下限和防止转变为电弧的上限之间。接着，使用通常用于合成金刚石的被氢稀释的甲烷源气体，通过改变施加的电压、压力和脉冲宽度，实现了两种不同类型的良好控制的分层等离子体。一种是等离子体形成的瞬态结构，另一种是在阳极附近具有强发光正柱的准稳态结构。在此基础上，通过在常规直流等离子体上叠加超短高压脉冲等离子体，实现了金刚石CVD过程的主动控制。结果表明，超短脉冲等离子体能显著提高衬底表面的离子密度，且峰值电压越高、脉宽越长、气压越低，这种效应越明显。这可能是由于第二类分层等离子体结构的实现提高了基片表面附近关键自由基物种的过饱和水平