초록 ▼

A method and system for measuring whole-wafer etch pit density (rD) is disclosed in which an etch GaAs wafer is tested for fractional transmission at a plurality of points over its surface. The fractional transmission (T) of light through the wafer is detected, amplified and fed to a computer where

A method and system for measuring whole-wafer etch pit density (rD) is disclosed in which an etch GaAs wafer is tested for fractional transmission at a plurality of points over its surface. The fractional transmission (T) of light through the wafer is detected, amplified and fed to a computer where at least two points of transmission measurement are selected for calibration. From these measurements, together with an estimate of the average etch pit size (area), the values for fractional transmission in regions of low etch pit density TO and high etch pit density TE may be calculated, and used to convert transmission data directly to etch pit density (rD) according to the equation [Figure]

대표청구항 ▼

A method for producing a map of etch pit density in a GaAs wafer surface, comprising the steps of: a. determining etch pit density (rD) at at least two points on said GaAs wafer surface; b. focusing a light source of predetermined wavelength at a plurality of points on said GaAs wafer surface; c. de

A method for producing a map of etch pit density in a GaAs wafer surface, comprising the steps of: a. determining etch pit density (rD) at at least two points on said GaAs wafer surface; b. focusing a light source of predetermined wavelength at a plurality of points on said GaAs wafer surface; c. detecting the fractional transmission (T) of said light source through said GaAs wafer surface at said plurality of points; d. selecting two locations on said GaAs surface where one of said at least two points in step a is in common with one of said plurality of points in step c; one of the locations being in an area of said GaAs wafer surface having relatively high transmission and other in an area having relatively low transmission; e. determining the average area (a) of etch pits on said GaAs wafer surface; f. calibrating a reference transmission point (TO) from the fractional transmission and the etch pit density at one of said two locations in step d where the transmission is high; g. calibrating a reference transmission point (TE) from the fractional transmission and etch pit density at the other of said two locations in step d where the transmission is low; and h. generating a map of etch pit density (rD) at each of said plurality of points according to the equation [Figure]