Simultaneous and Accurate Formation of Variously Shaped Holes in Silicon Substrate

Abstract

An electrochemical etching method for forming high-precision holes in silicon substrates is presented. An n-type layer is formed in the periphery of the hole pattern in order to define accurately current flow and a solution (1:2 HF:H2O) which does not chemically attack silicon is used, The silicon substrate is etched from the back side of the silicon wafer by means of a novel electrochemical etching method. Circular and square holes spaced 400 mu m apart are formed simultaneously and accurately in a boron doped (100) silicon substrate. The circular and square holes are 400 mu m in diameter and 400 mu m on side, respectively. The combination of an n-type layer and electrochemical etching enables variously shaped holes which can be widely applied in silicon micromachining to be formed concurrently with high precision.