Study Of Si Based Strained Materials Process Technology

There has been a lot of interest in the Si-based (Si、SiGe) strained materials latelywith its advantage of high-mobility, adjustable band structure and compatibletechnology with traditional silicon processing and wide application in the high-speedand high-performance devices and circuits. In this dissertationr, our attention focus onbiaxially strained Si and SiGe considering the situation of domestic technology.Using K P method with the help of perturbation theory, E-k relation near minimaconduction band energy followed from linear deformation potential theory isdetermined. With the frame of K P theory, the E-k relation of valence band has beenderived by taking strained Hamiltonian perturbation into account.Based on Fermi’s golden rule and the theory of Boltzmann collision termapproximation, electron and hole scattering mechanism in strained Si and strained SiGeare studied, including ionized impurity, acoustic phonon, non-polar optical phonon andintervalley phonon scattering rates.And then, the theoretical relationship between carriermobility and stress in strained Si and strained SiGe material are obtained. Ourquantitative results can provide valuable reference to understand the Si-based strainedmaterial and devices physics and their design.During the development of epitaxy system for strained materails, hardware optionshave been optimized such as oxygen and carbon control in the strained layer, metalcontamination resistant, leakage rate and intrinsic resistivity of epitaxy system controland material growth reliabilty. During the development of manufacturing process, thecombined buffer layers growth technology and impurities diffussion converter/transformer inhibition technology are developed. Finally, we obtained high qualitystrained materials by the epitaxy growth system.Characterization technologies of Si-based strained materials compatible withconventional method have been proposed. The non-destructive analysis methods forrelaxed SiGe layer thickness testing and strained SiGe stacking faults and dislocationstesting are firstly developed. Testing speed is improved and testing cost is reducedby the application of these methods.Using Si-based strained materials obtained, series of strained MOSFET are carried out.Testing results show that Si-based Strain nMOSFETs has more improvement thanconventional Si nMOSFETs, current drive capability has increased205%;transconductance of strained SiGe quantum wells pMOSFET has increased105%comparing with Si pMOSFET. The actual measurement performance of the device validated indirectly the carrier mobility of strained materials prepared was significantlyenhanced.