Automated and Calibrated Whole Wafer Etch Pit Density Measurements in GaAs
A technique for automated measurement of whole-wafer etch pit density (EPD) for GaAs wafers is presented. The technique relies on an infrared transmission experiment similar to that used to measure EL2 concentration. A theoretical relationship between transmission and EPD is established, including effects due to pit size. The new automated and old visual-count methods are compared on a 3“, low-pressure, liquid-encapsulated Czochralski wafer; it is established that the automated method has much better repeatability. An [EL2] map of this same wafer is also presented.
Sewell, J. S.,
Dudley, S. C.,
Mier, M. G.,
Look, D. C.,
& Walters, D. C.
(1989). Automated and Calibrated Whole Wafer Etch Pit Density Measurements in GaAs. Journal of Electronic Materials, 18 (2), 191-197.