Method of forming thin silicon mesas having uniform thickness.

摘要

An SOI wafer (10/20) has an epitaxial device layer (30) of initial thickness that is formed into a set of mesas (40) in the interval between which a temporary layer (42) of polysilicon is blanket deposited to a precisely controlled thickness. This polysilicon is entirely converted in a self-limiting process to an oxide etch stop pads (45) (having a thickness greater than the initial thickness) except on the mesa side walls. The mesas are thinned by a chemical mechanical polishing technique until the mesa is the same level as the top surface of the new oxide. The etch stop layer of oxide forming pads (45) is not removed but serves both as an isolating layer to provide dielectric isolation between final mesas (40') in the final circuit and also as a visual gauge to determine the time when the polishing process should stop.