Study Of The Defet Controlling Methods For Si Based Strained And Relaxed Materials

The issue issue was supported 973 National Key Project "Research of the basicTechnology of high speed integrated devices of Si Based Strained Materials" and theweaponry advanced research project "research of key technology of Strain Si CMOS"from Eleventh Five-Year Plan, which is the advancing front of the study in this field.Strained SiGe and strained Si is a kind of material and technology for Si CMOS tokeep on with the Moore's Law. Si based strained materials typical big mismatchedheterostructure materials. A great many dislocations will emerge in the interface of thesubstrate and epitaxial layer, which will severely affect the properties of the device.Reducing and controlling the threading dislocation density is one of the problemsdemanding prompt solution in present study of Si based strained and relaxed materials.We studied the critical thickness theory and its empirical models.We researchedinto several mechanism of the dislocations in Si based strained and relaxed materials.In this work we used the RPCVD device to study the dislocation densitycontrolling in Si based strained materials by Ge component gradual changing bufferlayer technology and low temperature Si buffer layer technology. We also studied thedefect behavior in Si based strained and relaxed materials. Differential InterferenceContrast Microscope and Transmission Electron Microscope experiments showed thatGe component gradual changing buffer layer technology and low temperature Si bufferlayer technology not only induced dislocations generating at the interface ofheterostructure and made the SiGe epitaxial layer greatly relaxed with a small thickness,but also prevented dislocations penetrating to the surface.We also focused on research of low dislocation density controlling methods forthin relaxed SiGe materials. We brought forth two optimized defect controlling methods:low temperature SiGe combining direct ion-implant technology and low temperatureSiGe combining indirect ion-implant technology.Based on the principle of defect density controlling by ion-implant technology, wefirstly put forward the post-ion-implant structure. The process is that growing an SiGehetero-epitaxial layer with a different Ge contents on the SiGe layer that prepared to berelaxed and implanting ions into the top SiGe layer. Plenty of dislocation loops wouldemerge in the top SiGe layer and glide into the top interface, which would relax the midSiGe layer. Comparing to the traditional ion-implant technology, our method reducedthe damage in SiGe layer from ion-implant and enhanced the quality of SiGe film.