Patent ID: 6177285
Filing Date: 2001-01-23
Classification: H01L,Y10S

Abstract:
A method of determining crystal orientation in a wafer, the wafer being made of crystal with a zinc-blend crystal structure, comprising the steps of:applying an etching mask on the wafer in a determined position relative to a preexisting marking of the wafer, the etching mask having mask openings arranged next to each other, each of the mask openings including two segments, the two segments aligned parallel to each other in a longitudinal direction, a first segment of the two segments being shorter than a second segment of the two segments, each of the mask openings further including a portion extending between the first segment and the second segment, the portion being longer than the first segment and the second segment, the first segment, the second segment, and the portion together forming a double-T-shaped mask opening, the first segment and the second segment being positioned at a first predetermined distance from each other in a longitudinal direction, and the portions of the mask openings being positioned at a second predetermined distance from each other;anisotropically etching the wafer to form i) etched-out channels corresponding to the mask openings, and ii) undercut areas between the mask openings; anddetermining the crystal orientation as a function of a distance of one of the channels adjacent to a first one of the undercut areas to the preexisting marking, the first one of the undercut areas having an intervening space between two adjacent channels that is the largest of all intervening spaces between adjacent ones of the channels.