Patent ID: 6483594
Filing Date: 2002-11-19
Classification: G01N

Abstract:
A method for performing a measurement in a region of a semiconductor substrate having a plurality of background carriers, the method comprising:creating a plurality of excess carriers in the region, a first number of excess carriers in the plurality moving out of the region by diffusion and having an aperiodic profile defined by a diffusive solution of a time dependent diffusion equation, a second number of excess carriers in the plurality having a periodic profile defined by a wave solution of said time dependent diffusion equation, wherein a profile of the excess carriers in the region is a superposition of the wave solution on the diffusive solution; and measuring amplitude and phase of an interference signal, the interference signal being obtained by interference between: a reference beam; and a portion of a probe beam of electromagnetic radiation reflected by the first number of excess carriers in the region, the portion of the probe beam being modulated in phase with modulation of the first number of excess carriers.