A Comparison of Chemical Etches for Revealing <100> Silicon Crystal Defects

The Sirtl etch is commonly used for <111> and <100>Si crystal defect evaluation although it is known that misleading results can occur for <100>Si due to lack of etch pit formation. A few of the known factors governing Si etching are presented for a qualitative approach to the understanding of defect etch formulations. In particular, the etch pit results from the Sirtl, Secco, Dash, and an experimental etchant are compared for shallow diffused structures as well as initial starting Si wafers. The best etch pit results were obtained from the Secco etch.