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

摘要

The evolution of the loading effect in Si_(1-x)Ge_(x) layers (0≤x≤20) versus growth parameters has been investigated for selective and nonselective growth using silane- and dichlorosilane-based epitaxy. Various methods have been examined in order to reduce the loading effect, and their influence on the defect density will be further discussed. High-resolution x-ray diffraction and atomic force microscopy were applied as the main tools in these investigations. It is shown that SiGe epitaxy is strongly sensitive to the opening size on the patterned substrates. This dependence is affected by the chemistry of the deposition. This effect can be decreased by adding HCl to the gas mixture or decreasing the growth 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 effect without degrading the epitaxial quality of the layer.