Precision alignment of mask etching with respect to crystal orientation

For most micro-mechanical devices, a high precision alignment of mask patte rn to crystal orientation is preferred. Such alignment even becomes critica l for devices that simultaneously require a smooth sidewall and minimal und ercut. In this article, we present an innovative pre-etching pattern to det ermine the [110] crystal orientation on [100] silicon wafers. This pattern etched on the wafer allows us to determine the crystal orientation within a n accuracy of 0.01 degrees. Such a pre-etching pattern can be used as a val uable reference for all subsequent mask patterns.