A study bipolar phototransistor action existing in CMOS process triggered by a laser beam used in a C-AFM system

Abstract

A beam bounce technique in a conductive atomic force microscope (C-AFM) system is usually used to enable the probe head to measure extremely small movements of the cantilever as it is moved across the surface of the sample. However, the laser beam used for the beam bounce also gives rise to the photoelectric effect while we are measuring electrical characteristics of a device. The photoelectric effect occurring in NMOSFETs caused by a laser beam used in the C-AFM system has been reported [1]. In this study, the photoelectric effect occurring in PMOSFETs will be discussed. An example that an invisible implant defect in a PMOSFET was successfully identified using the C-AFM based on the measured electrical characteristics and the bipolar phototransistor action models will also be introduced.