Abstract: A technique for automatically identifying a semiconductor wafer (30) having bar code identification indicia (32) on the front surface (31) thereof. Reading of the code is achieved by rotating the wafer about an axis (34) perpendicular to its front surface (31); directing a beam of radiant energy (37) at the code (32) along a predetermined direction relative to the front surface (31); and sensing, while rotating the wafer, the reflected radiant energy (39) within a second predetermined angular direction relative to the front surface. The bar code used herein is preferably a modified or "stretched" bar code 39 formed on the front surface of the wafer, and having an aspect ratio (i.e., dimension of a space/dimension of a bar) ranging from 1 to 4 (FIG. 2).

Abstract: Method of anisotropically etching a semiconductor substrate (32). The substrate (32) is placed in an evacuated reaction chamber (50) and exposed to a gas plasma (63) which has been excited with an AC source having a frequency greater than 0 Hz but less than 300 KHz. The pressure in the chamber, and chamber geometry, are such that the volume power density of the plasma is less than 0.01 W/cm.sup.3.