Biased-voltage controlled thinning for bonded silicon-on-insulator wafers

A novel method for the preparation of bonded and etch-back silicon-on-insulator is presented and demonstrated in which the surface of the to be thinned silicon wafer near the oxide is biased to inversion, so the bulk of this silicon wafer can be removed by anodic etching using the depletion layer as an etch stop. The high etching selectivity between the bulk silicon wafer and the depletion layer makes it possible to produce a micron/submicron-thick active silicon layer with good thickness uniformity across a 3 in. silicon-on-insulator wafer.