Characterization of denuded zones in internally gettered silicon wafers by electron beam induced current measurements

In the electron beam induced current (EBIC)-measurements, the minimum detectable denuded zone (DZ) width is determined by the beam voltage. Gettering was observed by comparing intentionally contaminated and non-contaminated samples at low beam voltage. In gettering, impurity atoms are transferred from the active surface region of a wafer to some location where they do not adversely affect the device performance. Oxygen precipitation close to the wafer surfaces is suppressed due to the outdiffusion of oxygen and so-called denuded zones are formed. The DZ width can be approximated to be two times of the oxygen diffusion length in the first Hi-treatment. The DZ width can be measured from the cross-section ofiG wafers by EBIC-imaging and line scanning. The results are in agreement with other methods: scanning infrared microscopy, Wright-etch and surface photovoltage.