An apparatus for heating a semiconductor wafer includes the following: a microwave source; an applicator cavity; and, a fixture for supporting a wafer in the applicator cavity. The fixture comprises a dielectric member providing mechanical support for the wafer and a metallic ring disposed generally parallel to and concentric with the wafer at a selected distance from the wafer, whereby the application of microwave power to the wafer may be adjusted to compensate for edge effects. An associated method for heating a semiconductor wafer comprises the steps of: a. placing the wafer in a microwave applicator cavity; b. supporting the wafer on a fixture, the fixture comprising a dielectric supporting member in contact with the wafer and a metallic ring member disposed generally parallel to and concentric with the wafer at a selected distance from the wafer; and, c. introducing microwave power into the applicator cavity in order to heat the wafer, with the metallic ring serving to modify the power distribution near the wafer edge. The apparatus may be adapted to various operations in semiconductor device fabrication and testing.