Automated X-ray rocking curve mapping for large area wafer characterization.
29 October 1987
An automated sample translation stage has been added to an existing x-ray double crystal diffractometer and interfaced to a data acquisition system controlled by an AT&T PC 6300 personal computer. The hardware and software of this new automation which can accommodate wafers with diameters as large as 2 inches are described, and example results are presented for an MOCVD grown In sub (1-x) Ga sub x As/InP wafer measuring 14x28 mm. From rocking curve data for the (400) reflection wafer maps of the mismatch, layer thickness (as obtained from Pendellosung fringe spacings), and crystalline perfection (as obtained from full width at half maximum values) have been obtained and are presented. A large portion of the wafer was found to be highly perfect.