Non-destructive method and apparatus for monitoring carrier lifetime of

Abstract

A non-destructive method for monitoring the carrier lifetime characteristic of a fabricated semiconductor sample during the fabrication process, where selected materials are deposited on a planar surface of a wafer substrate in a fabrication chamber, employs one or more viewports in the walls of a fabrication chamber, thus avoiding any alteration of the fabrication process. A focused electromagnetic wave is generated external to the fabrication chamber, and directed through a viewport to impinge upon a selected portion of the planar surface of the wafer substrate at an oblique incident angle relative to the planar surface of the wafer substrate. In turn, a reflected electromagnetic wave emanating from the planar surface of the wafer substrate is detected. A light source, also external to the fabrication chamber, generates light directed at the wafer substrate through a viewport. The light is intended to have wavelength components capable of generating hole-electron pairs in the wafer substrate. In turn, the dynamic response of the reflected electromagnetic wave, in response to the light being changed from a light on condition to a light off condition, is utilized for determining a quantity indicative of the carrier lifetime characteristic of the fabricated semiconductor sample.