Noncontact Measurement of Generation Lifetime

Abstract

In this paper, we discuss the measurement of minority carrier generation lifetime by the noncontact metal-insulator-semiconductor (MIS) method. This method enables electrical measurements on metal-air-insulator-semiconductor (MAIS) structure utilizing the air gap and is based on the conventional MIS theory. Capacitance-time ( C-t) measurement is employed for the lifetime evaluation in this method. The generation lifetime and the surface generation velocity are determined by Zerbst analysis, similar to the case of a conventional MIS capacitor formed with gate electrodes. For Si substrate with a long lifetime, the conventional MIS method has the disadvantage of long measurement time. However, MAIS structure reduces the measurement time by increasing the air gap distance. This is because the air gap is equivalent to a thick oxide film. In our experiment, metal-contaminated Si wafers were used to compare the MAIS method with the conventional MIS method in terms of the generation lifetime. The experimental results obtained from the two methods showed good agreement.