In order to accomplish reliable mechanical design of MEMS, the infuences of surface roughness and octadecyltrichlorosilane (OTS) self-assembled monolayers (SAMs) on the mechani- cal properties of micromachined polysil...In order to accomplish reliable mechanical design of MEMS, the infuences of surface roughness and octadecyltrichlorosilane (OTS) self-assembled monolayers (SAMs) on the mechani- cal properties of micromachined polysilicon flms for MEMS are investigated. Surface efect on the fracture properties of micromachined polysilicon flms is evaluated with a new microtensile testing method using a magnet-coil force actuator. Statistical analysis of the surface roughness efects on the tensile strength predicated the surface roughness characterization of polysilicon flms being tested and the direct relation of the mechanical properties with the surface roughness features. The fracture strength decreases with the increase of the surface roughness. The octadecyltrichlorosi- lane self-assembled monolayers coating leads to an increase of the average fracture strength up to 32.46%. Surface roughness and the hydrophobic properties of specimen when coated with OTS flms are the two main factors infuencing the tensile strength of micromachined polysilicon flms for MEMS.展开更多
A new physical current-voltage model for polysilicon thin-film transistors （poly-Si TFTs） is presented. Taking the V-shaped exponential distribution of trap states density into consideration,explicit calculation of ...A new physical current-voltage model for polysilicon thin-film transistors （poly-Si TFTs） is presented. Taking the V-shaped exponential distribution of trap states density into consideration,explicit calculation of surface potential is derived using the Lambert W function, which greatly improves computational efficiency and is critical in circuit simulation. Based on the exponential density of trap states and the calculated surface potential, the drain current characteristics of the subthreshold and the strong inversion region are predicted. A complete and unique drain current expression, including kink effect, is deduced. The model and the experimental data agree well over a wide range of channel lengths and operational regions.展开更多
半导体产业是支撑经济社会发展和保障国家安全的基础性、战略性和先导性产业,单晶硅由于具有独特的物理及化学性质,在半导体产业中占有重要的地位,多晶硅作为制备单晶硅的前驱体,对纯度的要求尤为严苛,因此本文研究了一种采用低成本混...半导体产业是支撑经济社会发展和保障国家安全的基础性、战略性和先导性产业,单晶硅由于具有独特的物理及化学性质,在半导体产业中占有重要的地位,多晶硅作为制备单晶硅的前驱体,对纯度的要求尤为严苛,因此本文研究了一种采用低成本混酸清洗多晶硅块,进而制备高纯多晶硅的新型方法。在室温环境中,采用纯度为电子级(EL)、超纯(UP)、超纯MOS(UP-S)级的由氢氟酸和硝酸组成的混酸溶液清洗多晶硅块,所得多晶硅表面金属含量均在2 ppbw以下,即符合半导体级多晶硅对表面金属含量的要求;并研究了多晶硅表面金属含量与清洗过程所消耗EL级混酸之间的关系,发现使用300 ml V_(HF):V_(HNO3)=1:10的由氢氟酸和硝酸组成的EL级混酸溶液可以清洗出3.33kg半导体级多晶硅,说明低成本EL级混酸也可以广泛用于半导体级多晶硅的工业生产中。展开更多
A physical drain current model of polysilicon thin-film transistors based on the charge-sheet model, the density of trap states and surface potential is proposed.The model uses non-iterative calculations,which are sin...A physical drain current model of polysilicon thin-film transistors based on the charge-sheet model, the density of trap states and surface potential is proposed.The model uses non-iterative calculations,which are single-piece and valid in all operation regions above flat-band voltage.The distribution of the trap states,including both Gaussian deep-level states and exponential band-tail states,is also taken into account,and parameter extraction of trap state distribution is developed by the optoelectronic modulation spectroscopy measurement method. Comparisons with the available experimental data are accomplished,and good agreements are obtained.展开更多
A physical and explicit surface potential model for undoped symmetric double-gate polysilicon thinfilm transistors has been derived based on an effective charge density approach of Poisson＇s equation with both expone...A physical and explicit surface potential model for undoped symmetric double-gate polysilicon thinfilm transistors has been derived based on an effective charge density approach of Poisson＇s equation with both exponential deep and tail state terms included. The proposed surface potential calculation is single-piece and eliminatestheregionalapproach.Modelpredictionsarecomparedtonumericalsimulationswithcloseagreement,having absolute error in the millivolt range. Furthermore, expressions of the drain current are given for a wide range of operation regions, which have been justified by thorough comparisons with experimental data.展开更多
基金Project supported by Program for New Century Excellent Talents in University,the National Natural Science Founda-tion of China(Nos.50135040and50475124),the Excellent Young Teachers Program of MOE of China,the Foundation forthe Author of National Excellent Doctoral Dissertation of China(No.200330)and the National Basic Research Programof China(No.2004CB619305).
文摘In order to accomplish reliable mechanical design of MEMS, the infuences of surface roughness and octadecyltrichlorosilane (OTS) self-assembled monolayers (SAMs) on the mechani- cal properties of micromachined polysilicon flms for MEMS are investigated. Surface efect on the fracture properties of micromachined polysilicon flms is evaluated with a new microtensile testing method using a magnet-coil force actuator. Statistical analysis of the surface roughness efects on the tensile strength predicated the surface roughness characterization of polysilicon flms being tested and the direct relation of the mechanical properties with the surface roughness features. The fracture strength decreases with the increase of the surface roughness. The octadecyltrichlorosi- lane self-assembled monolayers coating leads to an increase of the average fracture strength up to 32.46%. Surface roughness and the hydrophobic properties of specimen when coated with OTS flms are the two main factors infuencing the tensile strength of micromachined polysilicon flms for MEMS.
文摘A new physical current-voltage model for polysilicon thin-film transistors （poly-Si TFTs） is presented. Taking the V-shaped exponential distribution of trap states density into consideration,explicit calculation of surface potential is derived using the Lambert W function, which greatly improves computational efficiency and is critical in circuit simulation. Based on the exponential density of trap states and the calculated surface potential, the drain current characteristics of the subthreshold and the strong inversion region are predicted. A complete and unique drain current expression, including kink effect, is deduced. The model and the experimental data agree well over a wide range of channel lengths and operational regions.
文摘半导体产业是支撑经济社会发展和保障国家安全的基础性、战略性和先导性产业,单晶硅由于具有独特的物理及化学性质,在半导体产业中占有重要的地位,多晶硅作为制备单晶硅的前驱体,对纯度的要求尤为严苛,因此本文研究了一种采用低成本混酸清洗多晶硅块,进而制备高纯多晶硅的新型方法。在室温环境中,采用纯度为电子级(EL)、超纯(UP)、超纯MOS(UP-S)级的由氢氟酸和硝酸组成的混酸溶液清洗多晶硅块,所得多晶硅表面金属含量均在2 ppbw以下,即符合半导体级多晶硅对表面金属含量的要求;并研究了多晶硅表面金属含量与清洗过程所消耗EL级混酸之间的关系,发现使用300 ml V_(HF):V_(HNO3)=1:10的由氢氟酸和硝酸组成的EL级混酸溶液可以清洗出3.33kg半导体级多晶硅,说明低成本EL级混酸也可以广泛用于半导体级多晶硅的工业生产中。
基金Project supported by the Key Project of Chinese Ministry of Education(No.211206)the Fundamental Research Funds for the Central Universities (No.21611422)the Foundation for Distinguished Young Talents in Higher Education of Guangdong,China(No.LYM10032)
文摘A physical drain current model of polysilicon thin-film transistors based on the charge-sheet model, the density of trap states and surface potential is proposed.The model uses non-iterative calculations,which are single-piece and valid in all operation regions above flat-band voltage.The distribution of the trap states,including both Gaussian deep-level states and exponential band-tail states,is also taken into account,and parameter extraction of trap state distribution is developed by the optoelectronic modulation spectroscopy measurement method. Comparisons with the available experimental data are accomplished,and good agreements are obtained.
基金Project supported by the National Natural Science Foundation of China(No.61204100)the Guangdong Natural Science Foundation(No.S2013010013088)
文摘A physical and explicit surface potential model for undoped symmetric double-gate polysilicon thinfilm transistors has been derived based on an effective charge density approach of Poisson＇s equation with both exponential deep and tail state terms included. The proposed surface potential calculation is single-piece and eliminatestheregionalapproach.Modelpredictionsarecomparedtonumericalsimulationswithcloseagreement,having absolute error in the millivolt range. Furthermore, expressions of the drain current are given for a wide range of operation regions, which have been justified by thorough comparisons with experimental data.
