A technique for determining beam parallelism on a medium current implanter using the Therma-Wave Therma-Probe

A technique has been developed using the Therma-Wave Therma-Probe which allows the quantification of the angle of incidence of the ion beam to the wafer crystal structure in a parallel scanned implanter. A Therma-Wave value vs. incident angle calibration curve is developed from an electrostatically scanned implanter where the variation in beam incident angle varies significantly over the wafer and is well characterized. This calibration curve is then applied to maps of wafers implanted in a parallel scanned implanter, the Eaton NV-8200P. Changes in the measured Therma-Wave value are then correlated to variations in the ion beam's angle of incidence to the wafer crystal structure. The sensitivities and accuracy of this technique, along with possible limitations, are discussed.