High-Resolution Electron Microscopy of Process-Induced Defects in Silicon

Abstract

AbstractSeveral examples of defect characterization which are of topical inter-est to Si device technology are presented. The results obtained by high-reso-lution electron microscopy (HREM) are discussed in context with the actual defect problem. - Reinvestigation of platelike defects in Si produced by reactive ion etching in hydrogen containing plasmas (CHF3) shows that some of the {111} platelets are of extrinsic nature. The defects contain probably both constituents from the plasma and Si-interstitials created by the impin-ging ions. - A high dose As-implantation forms an amorphous Si surface layer which has a sharply curved amorphous/crystalline (a/c)-interface below the implantation mask edge. Annealing at 900°C leads to formation of vacancy-type defects under the mask edge. This is due to the different regrowth rates on the various lattice planes of the curved a/c-interface. - Metal-silicide pre-cipitation at the SiO2/Si interface reduces the breakdown field strength of thin oxides. The main failure mechanism observed in model experiments is the thinning of the oxide layer thickness. - Additional x-ray peaks which are frequently observed in low-pressure chemical vapour deposited (625 7deg;C) po-lycrystalline Si layers arise from a diamond hexagonal Si phase. Small inclu-sions and bands of this phase were for the first time directly observed by HREM.