METHOD AND APPARATUS FOR NONDESTRUCTIVE MEASUREMENT AND MAPPING OF SHEET MATERIALS

An apparatus for contactless measurement of carrier concentration and mobility includes a microwave source, a circular waveguide for transmitting microwave radiation to a sample, such as a semiconductor wafer or panel for flat panel displays, at a measurement location, a first detector for detecting the forward microwave power, a second detector for detecting the microwave power reflected from the sample, and a third detector for detecting the Hall effect power. A circular waveguide, carrying only the TE11 mode, is terminated by the sample behind which a short is located. Perpendicular to the plane of the sample (and along the axis of the circular waveguide), a magnetic field is applied. In this configuration, a given incident TE11 wave will cause two reflected waves. One is the ordinary reflected wave in the same polarization as the incident one. A detector is provided to measure this reflected radiation. The other reflected wave is caused by the Hall effect. Its polarization is perpendicular to the former wave and a probe is provided to detect this as well. This reflected wave is detected by a probe, the output of which is combined with an attenuated and phase shifted portion of the forward radiation at a single detector.