Selective back side reactive ion etch

摘要

According to an example embodiment, a semiconductor device having a back side and a circuit side opposite the back side is analyzed. The semiconductor device includes bulk silicon in the back side and also includes epitaxial silicon. An ion gas comprising SF6 and N2 is directed at a target region in the back side. Using the ion gas, the target region in the back side is selectively etched using reactive ion etching (RIE) and an exposed region is formed. The etching is selective to the bulk silicon. When the etching process encounters the epitaxial silicon, the etch rate slows and is used as an endpoint indicator of the selective etching process. Once the etching process is stopped, the circuitry is accessed via the exposed region.