Study Of Defect Mechanism And Characterization For Si Based Strained And Relaxed Materials

Strained SiGe and strained Si is a better kind of material and technology than Si CMOS to keep on with the Moore's Law. Due to the large lattice mismatch between the layer and the substrate, the epitaxial film often receives a high dislocation density, which greatly degrades the device performance. For Reducing and controlling the threading dislocation density, it is necessary to have a research on defect mechanism and characterization for Si based strained and relaxed materials.We researched into the shape, formation mechanism, character, behavior, nucleation and multiplication mechanism of dislocation in Si based strained and relaxed materials, we also have a good research on the observation of the defect and the characterization of dislocation density.In this work we used the RPCVD device to epitaxial the Si based strained and relaxed materials, the behavior of defect are analyzed by TEM and the density dislocation was characterized by etching. According to the results of research, Ge component gradual changing buffer layer technology and low temperature Si buffer layer technology can both greatly reduce the threading dislocation density.To get a better etch result, we did a lot of experiments by changing etching solution and etching time. We proposed the ideal of gradient etching .By this method ,we can do many experiments in one sample, determine the etching time with different layer structure easily,and it can improve the observe result of etching.