Selektive und nicht-selektive Ablagerung von Si1-x Gex auf einem mit SiO2 teilweise beschichteten Si-Wafern

摘要

Several methods are disclosed for minimizing the number of through film defects of misfit dislocations in a SiGe layer on a partially oxide masked Si substrate. In the first embodiment the silicon dioxide layer is first hidden by covering that layer with either silicon nitride or polycrystalline silicon before depositing the SiGe layer on the exposed Si of the substrate and the hidden layer of the oxide to minimize defects in the SiGe layer. The second embodiment, also for minimizing defects in the SiGe layer, begins with a first SiO2 layer grown on the substrate which is then anisotropically dry etched to form windows through the first SiO2 layer to expose the Si of the substrate. Next, a thin second SiO2 layer is deposited on the first SiO2 layer and at the bottom of the windows to repair the Si substrate surface damaged in the anisotropic etch; then the second SiO2 layer is wet etched from the bottom surface of the windows to expose the Si surface of the substrate. Finally, a SiGe layer is selectively deposited within the windows. The third embodiment also minimizes the defects in the SiGe layer being accomplished by first growing a SiO2 layer on the substrate, followed by masking for lithographically opening windows through the SiO2 layer with the total area of all of the windows being maximized with respect to the total area of the SiO2 to be left on a portion of the surface of the substrate. Then etching windows in the SiO2 layer using the mask to expose the Si surface of the substrate through those windows, and then selectively depositing a SiGe layer within the windows. Next, the fourth embodiment minimizes the misfit dislocations in the SiGe layer by growing a SiO2 layer on the substrate surface, then masking for lithographically opening windows through the SiO2 layer with the area of each of the windows being minimized. Then the mask is used to etch windows in the SiO2 layer to expose the Si surface of the substrate through those windows, and then selectively depositing a SiGe layer within the windows. The fifth embodiment is a combination of the first and fourth embodiments to minimize the number of defects and misfit dislocations in the SiGe layer.