In situ defect etching of strained-Si layers with HCl gas

Experiments on in situ chemical etching of strained-Si films with gaseous HCl in a commercial CVD reactor are reported. After growth of a virtual Si1-xGex substrate and the deposition of a strained-Si cap layer HCl is applied at 800 °C. A pronounced dependence of the average etch rate on the strain of the Si cap layer is observed. Furthermore, the etch process is sensitive to crystal defects, leading to etch pits at the site of threading dislocations. This kind of defect etching allows to characterize the number and distribution of threading dislocations on the whole wafer area (e.g. 200 mm) without additional equipment costs.