Hybrid-Optimal Control of Reactive Low frequency Discharge plasmas

本研究的目的是基于微观碰撞过程，从实验和理论上实现碳膜在低气压、低频率放电条件下的定量控制系统。主要研究结果如下：(1)利用25 kHzf&lt；20 MHz的时空分辨光学发射光谱对CH4/H2气体中碳膜的射频放电进行了诊断。对鞘层宽度/自偏压与放电驱动频率的关系进行了详细的研究。与在Ar中的结果相比，在CH4/H2中维持电压的快速下降区的宽度比在Ar中要窄，并且出现了接近3 MHz的大自偏压。结果表明，当频率从20 MHz降低到100 kHz时，离子入射使薄膜表面的主要离子由H^+变为H^+。(2)从时空光学发射光谱上观察到离子碰撞使沉积物质从表面重新抛射，并从薄膜硬度的角度对这一现象进行了讨论。提出了用Boltzmann方程分析鞘层离子能量分布的方法，并在Ar辉光放电中验证了该方法的有效性。(4)建立了甲烷射频辉光放电模型。

The purpose of the present study is to realize the quantitative control system of the carbon thin film at low gas temperature at low frequency discharge experimentally and theoretically, based on the microscopic collision processes. The main results are as follows:(1) RF discharges in CH_4/H_2 for carbon film deposition has been diagnosed by spatiotemporally resolved optical emission spectroscopy between 25 kHz < f < 20 MHz. The relation between the sheath width/self-bias and the driving frequency of the discharge has been newly investigated in detail. In comparison with the results in Ar, the width of the rapidly decreasing region of the sustaining voltage is narrower in CH_4/H_2 than in Ar, and the appearance of the large self-bias voltage close to 3 MHz is found out. It is concluded that these phenomena are due to the change of the predominant ions from H^+, to H^+_ with increasing of f.(2) Reejection of the deposited species from the surface by the ion impact has been observed from the spatiotemporal optical emission spectroscopy, when the frequency decreases from 20 MHz to 100 kHz, and the phenomena are discussed from the viewpoint of the hardness of the deposition film. The impact energy of the ion will be observable by Doppler shift measurement.(3) The method to analyze the ion energy distribution in the sheath region has been proposed by using the Boltzmann equation, and the validity of the method is examined in Ar glow discharges.(4) Modeling of the RF glow discharge in CH_4 has been developed.