Semiconductor apparatus and process for producing the same, and process for making via hole

摘要

In a semiconductor apparatus, a plurality of HBTs (heterojunction bipolar transistors) are formed on a front surface consisting of a (100) crystal plane of a GaAs substrate. Via holes passing thorough the GaAs substrate are formed in proximity of the HBTs. Each via hole has a rectangular-shaped hole edge at the front surface side of the GaAs substrate. The longitudinal direction of the hole edge on the surface side of the via hole is parallel to the [011] direction of crystal orientation of the GaAs substrate. A width of the via hole in a direction perpendicular to the [011] direction of crystal orientation is larger at the back surface of the substrate than at the front surface thereof.