The development of the equipment for the ultra precision aspherical optics using plasma CVM.

等离子体CVM是一种利用等离子体在大气压力下形成自由基的加工方法。利用高压等离子体形成非常高密度的自由基，并且由于气体的平均自由程小，可以将等离子体产生区域限制在高电场影响的电极附近。因此，可以将加工效率和形状控制相结合，使其等同于机械加工。在本研究中，为了制作基于纯化学原理的新型形状生成加工系统，进行了以下几个项目的实践。1)进行了高精度高速旋转电极数控等离子体CVM加工系统的设计与制作。2)获得了对加工区域定位、加工速度和加工表面粗糙度影响较大的各加工参数的基本数据。3)对同步辐射波束线用硅制成的平面反射镜进行了加工。通过机械抛光得到的镜面平整度为158nm (p-v)，经过该系统的校正处理，达到22.5nm （p-v）。4)对下一代半导体衬底SOI （silicon On Insulator）硅片中的硅层进行了薄膜减薄。由于该体系对薄膜进行了减薄，将0.2μm厚度的SOI层减薄至0.04μm。

Plasma CVM is a machining method using the radical formed by the plasma over the atmospheric pressure. The very high-density radical is formed by utilizing the high pressure plasma, and it is possible to limit the plasma generation region to the vicinity of the electrode which the high electric field affects, because of the small mean free path of the gas. Therefore, it is possible to combine processing efficiency and shape control which are equal to the mechanical machining. In this study, to make the new shape generating processing system based on the purely chemical principle, following items were practiced.1) Design and production of the numerical controlled plasma CVM machining system using the high-precise high-speed rotary electrode were carried out.2) Basic data on each machining parameter which give large effect in the localization of machining area, machining speed and machined surface roughness, were acquired.3) The plane mirror made of the silicon for synchrotron radiation beam line, was processed. Though the flatness of the mirror got by the mechanical polishing was 158nm (p-v), as a result of correction processing by this system, 22.5nm (p-v) was achieved.4) Film thinning of the silicon layer in SOI (Silicon On Insulator) wafer which was next generation semiconductor substrate was done. As a result of film thinning by this system, it succeeded in thinning the SOI layer of 0.2μm thickness to 0.04μm.