method for contactless measurement of the specific electrical conductivity of cameras

摘要

The electrical conductivity of a lamella of conducting material (e.g., semiconductor wafers or metal films) is measured by introducing the lamella into the oscillatory magnetic field of the inductive element of the L-C tank circuit. The tank circuit is the frequency determining portion of an oscillator which is adjusted, upon sample introduction, to restore the magnitude of oscillation. With suitable choice of circuit parameters, the incremental current in the tank circuit is linearly proportional to the sheet conductivity of the lamella. An exemplary apparatus, operating at approximately 10 MHz with a 1 cm.sup.2 measurement area exhibited approximately 1% linearity over a 100 to 1 range of conductivity with a resolution of approximately one part in 10. sup.4 with a limiting sensitivity of 10.sup.11 carriers per square cm.