Delineation of crystalline extended defects on multicrystalline silicon wafers

Abstract

We have selected Secco and Yang etch solutions for the crystalline defect delineation on multicrystalline silicon (mc-Si) wafers. Following experimentations and optimization of Yang and Secco etching process parameters, we have successfully revealed crystalline extended defects on mc-Si surfaces. A specific delineation process with successive application of Yang and Secco agent on the same sample has proved the increased sensitivity of Secco etch to crystalline extended defects in mc-Si materials. The exploration of delineated mc-Si surfaces indicated that strong dislocation densities are localized mainly close to the grain boundaries and on the level of small grains in size (below 1 mm). Locally, we have observed the formation of several parallel dislocation lines, perpendicular to the grain boundaries. The overlapping of several dislocations lines has revealed particular forms for etched pits of dislocations.