Loading effect in SiGe layers grown by dichlorosilane- and silane-based epitaxy

The evolution of the loading effect in Si1-xGex layers (0 less than or equa l tox less than or equal to 20%) versus growth parameters has been investig ated for selective and nonselective growth using silane- and dichlorosilane -based epitaxy. Various methods have been examined in order to reduce the l oading effect, and their influence on the defect density will be further di scussed. High-resolution x-ray diffraction and atomic force microscopy were applied as the main tools in these investigations. It is shown that SiGe e pitaxy is strongly sensitive to the opening size on the patterned substrate s. This dependence is affected by the chemistry of the deposition. This eff ect can be decreased by adding HCl to the gas mixture or decreasing the gro wth rate. Meanwhile, adding HCl during the growth of SiGe layers or using a low growth rate decreases the epitaxial quality of the layers. Depositing a Si seed layer prior to the growth of the SiGe layer reduces the loading e ffect without degrading the epitaxial quality of the layer. (C) 2001 Americ an Institute of Physics.