多晶硅纳米膜表层钝化的研究

哈尔滨工业大学工程硕士学位论文AbstractDue to their favorable piezoresistive properties and good temperature stability,polysilicon nanofilms have been applied in piezoresistive sensing devices.Moreover,the ohmic contact of metal electrodes is one of the important factorsdetermining the proformances of sensors.Therefore,improving the ohmic contactproperties has a significant role on the proformance enhancement and application ofsensing devices.We study the principle and characteristic of ohmic contacts topolysilicon nanofilms.The energy band theory and transport mechanism of ohmic contacts wereanalyzed,the measure methods.of specific contactcs resistivity which reflectsmetal-semiconductor's characteristic were compared,we adopt transmission linemodel (TLM )and circular dot transmission line model (CDTLM).The 80nm polysilicon nanofilms were deposited on thermally oxidized Si(100)substrates by Low Pressure Chemical Vapor Deposition (LPCVD).Themicrostructure of polysilicon nanofilms was characterized by Atom ForceMicroscope (AFM);crystallography structure of Al/polysilicon nanofilms afterannealing at various temperatures and periods was characterized by X-raydiffraction (XRD).The natures of common metal materials were analyzed.The ohmic contactsamples based on Al monolayer were fabricated.In different annealing conditionincluding temperature and time,the resistances between different electrodedistances were measured and analyzed based on TLM and CDTLM methods.Thecontact resistivity is 3.0726x10-10.cm2 before annealing.The anneal condition is450C,20min,monolayer metal Al ohmic contact resistance was increased by twoor three orders of magnitude,average contact resistivity is 2.41x10-30.cm2.Thecurrent-voltage (I-V)characteristic had not shown ohmic contact characteristicbefore annealling,but after annealling it is improved obviously.Keywords:polysilicon nanofilms,ohmic contacts,transmission line model,contactresistivity-Ⅱ-