Induced Pits Formation And Its Influence On The Phototoelectro Chemical Etching For Macroporous Silicon

Macroporous silicon can be used in many fields such as microchannel plate and photonic crystals. Before preparing a regular arranged macroporous silicon array structure,the induced pit should be prepared on the surface of silicon. In this paper, the anisotropic wet etching process of induced pit was studied. The preparation process of ohmic contact layer was determined. It was analyzed that the problems during lithography process. Then a reliable technological conditions of lithography process were given as well. KOH solution was selected to etch induced pit which has a inverted pyramid structure. The process of induced pit etching by inductively coupled plasma(ICP) was studied and its theory and experiment were analyzed. The ICP process of etching the macroporous silicon array was discussed. The theories of the lag effect of deep silicon etching, the structure of stripe and RIE grass in hole wall were analyzed. The influences of different preparation techniques on macroporous silicon photoelectrochemical etching were studied. At the beginning of photoelectrochemical etching, the induced pit with structure of inverse pyramid can lead to bottleneck effect. It also can cause blind holes. The induced pit with structure of inverse quadrangular frustum makes the macroporous silicon bifurcation phenomenon. It is not necessary to make a sharp structure at the bottom of induced pit when preparing it, but the induced pit which no sharp will expand the dimension of macroporous silicon. When the depth of induced pit by ICP etching is much greater than the width, the bifurcation phenomenon of macroporous silicon will not come out in photoelectrochemical etching.