GENERATION OF MICRO-ICE JET AND SELECTIVE REMOVAL PROCESS OF RESINOID INSULATOR FILM FOR MULTIPLAYER SEMICONDUCTORS

本计画系针对半导体树脂隔离膜之通孔加工，开发可间歇喷射微冰之微冰喷射加工装置。IJM工艺类似于磨料喷射加工（AJM），并选择性地去除比纯水的微冰更软的材料。IJM使用在-150 ℃或更低的低温条件下生产的细冰粉。首先，利用粒子图像测速仪（PIV）对喷嘴的喷雾形态和喷射速度分布进行了测量。根据测量的喷雾形态和计算的水滴临界冻结时间，设计了IJM装置的冰室尺寸。然后，我们研究了IJM工艺的爆破特性和可能性。当来自喷嘴的冰射流聚焦到工件上时，可以加工小孔或槽。爆破后的微冰融化，对生产过程的环境没有影响。Al、Cu、Si和树脂板用冰射流喷射。Al和Cu具有相似的硬度，不进行机械加工。但由于残余应力的存在，表面粗糙度增大，喷砂区中心位置升高。Si（单晶晶片），比微冰硬，没有加工，对表面没有影响。除去比微冰软的树脂。然后，我们在硅晶片上制作树脂隔离膜，并重叠金属掩模。一道道冰箭轰在了面具上。仅去除树脂隔离膜，并且将掩模的相同图案转录到膜上。选择性去除过程进行了演示。

This project describes the development of the micro-ice jet machining (IJM) device for the via fabrication on the resin isolation film of semiconductors, which is capable of intermittent blasting of micro-ice. The IJM process is similar to an abrasive jet machining (AJM), and selectively removes softer materials than the micro ice of pure water. IJM uses fine ice powders, which are produced under the low temperature condition of -150 ℃ or below. First, the spray pattern from the nozzle and the injected velocity distribution were measured using PIV (Particle Image Velocimetry) system. The size of ice chamber for IJM device was designed on the basis of measured spray pattern and calculated value of critical freezing time of water drop. Then, we investigated the blasting characteristics and the possibility of the IJM process. As the ice jet stream from the nozzle is focused onto the workpiece, small holes or slots can be machined. The blasted micro-ice is melted and has no influence upon the environment of production processes. Al, Cu, Si and resin plates were blasted with ice jet stream. Al and Cu, which have similar hardness, were not machined. The surface roughness, however, increased and its center of blasted area rises due to the residual stress. Si (single crystal wafer), which is harder than micro-ice, was not machined and has no influence on the surface. Resin, which is softer than the micro-ice, was removed. Then, we made a resinoid isolation film on the silicon wafer and a metal mask was overlapped. Ice jet was blasted on the mask. Only the resin isolation film was removed, and the same pattern of the mask was transcribed onto the film. The selective removal process was demonstrated.