HYDROGEN RELATED DEFECTS IN CZOCHRALSKI SILICON CLOSE TO THE WAFER SURFACE: DEFECT ANALYSIS AND TECHNOLOGICAL PROSPECTS

摘要

The formation of hydrogen related defects at the surface and in the subsurface regions of Czochralski silicon (Cz Si) will be studied on wafers, which were treated by hydrogen plasma and subsequent annealing. The properties of hydrogenated wafer surface and subsurface regions are analyzed by atomic force microscopy, scanning and transmission electron microscopy and μ-Raman spectroscopy. Two processes can be observed on hydrogen plasma treated Cz Si samples, i.e. i) a structuring at the wafers surface, and ii) the formation of hydrogen induced {111}- or {100}-platelets. Structuring occurs at the wafer surface down to a depth of about 100 nm with structure sizes well below 100 nm under appropriate conditions. The nucleation and formation of such structures can be controlled by the process conditions. The kinetic processes for the formation of the structured silicon layers will be explained in frame of an etching and re-deposition mechanism Since platelets can have a significant impact on the H-related surface structuring the mechanisms for the platelet formation will be also emphasized.