Patent ID: 8093920
Filing Date: 2012-01-10
Classification: G01R,H01L

Abstract:
1. A method for determining steady state diffusion length of minority carriers, L 0 , in semiconductor wafer, from the measurement of at least two diffusion length values L 1 and L 2 , under non-steady state conditions at frequencies ω 1 , and ω 2 , respectively, the method comprising: illuminating a wafer surface with light, which is modulated at a first frequency, ω monitoring first surface photovoltage signals of the wafer during illumination with the light modulated at the first frequency; determining a first diffusion length, L illuminating a wafer surface with light, which is modulated at a second frequency, ω monitoring second surface photovoltage signals of the wafer during illumination with the light modulated at the second frequency; determining a second diffusion length, L calculating a third diffusion length, L