Formation of titanium and cobalt germanides on Si (100) using rapid thermal processing

Titanium and cobalt germanides have been formed on Si (100) substrates using rapid thermal processing. Germanium was deposited by rapid thermal chemical vapor deposition prior to metal evaporation. Solid phase reactions were then performed using rapid thermal annealing in either Ar or N₂ ambients. Germanide formation has been found to occur in a manner similar to the formation of corresponding silicides. The sheet resistance was found to be dependent on annealing ambient (Ar or N₂) for titanium germanide formation, but not for cobalt germanide formation. The resistivities of titanium and cobalt germanides were found to be 20 μΩ-cm and 35.3μΩ-cm, corresponding to TiGe₂ and Co₂Ge, respectively. During solid phase reactions of Ti with Ge, we have found that the Ti₆Ge₅ phase forms prior to TiGe₂. The TiGe₂ phase was found to form approximately at 800° C. Cobalt germanide formation was found to occur at relatively low temperatures (425° C); however, the stability of the material is poor at elevated temperatures.     

Rapid thermal chemical vapor deposition of in-situ boron doped polycrystalline SIxGe1-x

In-situ doped polycrystalline Si_xGe_1-x (x = 0.7) alloys were deposited by rapid thermal chemical vapor deposition (RTCVD) using the reactive gases SiH₂Cl₂, GeH₄ and B₂H₆ in a H₂ carrier gas. The depositions were performed at a total pressure of 4.0 Torr and at temperatures 600° C, 650° C and 700° C and different B₂H₆ flow rates. The conditions were chosen to achieve high doping levels in the deposited films. Our results indicate negligible effect of B₂H₆ flow on the deposition rate. The depositions follow an Arrhenius type behavior with an activation energy of 25 kcal/mole. Boron incorporation in the films was found to follow a simple kinetic model with higher boron levels at lower deposition rates and higher B₂H₆ flow rates. As-deposited resistivities as low as 2 mΩ-cm were obtained. Rapid thermal annealing (RTA) in the temperature range 800-1000° C was found to reduce the resistivity only marginally due to the high levels of boron activation achieved during the deposition process. The results indicate that polycrystalline Si_xGe_1-x films can be deposited by RTCVD with resistivities comparable to those reported for in-situ doped polysilicon.     

可用于Ⅲ族氮化物生长的50mm 3C-SiC/Si(111)衬底的制备

利用新研制出的垂直式低压CVD(LPCVD)SiC生长系统,获得了高质量的50mm 3C-SiC/Si(111)衬底材料.系统研究了3C-SiC的n型和p型原位掺杂技术,获得了生长速率和表面形貌对反应气体中SiH4流量和C/Si原子比率的依赖关系.利用Hall测试技术、非接触式方块电阻测试方法和SIMS,分别研究了3C-SiC的电学特性、均匀性和故意调制掺杂的N浓度纵向分布.利用MBE方法,在原生长的50mm 3C-SiC/Si(111)衬底上进行了GaN的外延生长,并研究了GaN材料的表面、结构和光学特性.结果表明3C-SiC是一种适合于高质量无裂纹GaN外延生长的衬底或缓冲材料.     

基于MEMS技术的红外成像焦平面阵列

选用Au和LPCVD的低应力SiNx薄膜材料,采用MEMS技术研制了新型间隔镀金热隔离结构的薄膜镂空式非制冷红外成像焦平面阵列,并应用光学读出的方法成功地在室温(27.47℃)背景下获得了人体的热像.实验证明间隔镀金热隔离结构的引入有效抑制了热传导对变形梁温升的限制,从而大大降低了系统的噪声等效温度差(NETD),NETD达到约200mK.     

Structural and electrical properties of polycrystalline silicon films deposited by low pressure chemical vapor deposition with and without plasma enhancement

Silicon thin films prepared by chemical vapor deposition of silane at very low pressures (4 mTorr) in an experimental reactor that allows deposition with and without plasma enhancement have been characterized. The temperature range of the substrates on which the films were deposited was varied from 500 to 800° C for plasma-enhanced depositions and 600 to 800° C for nonplasma depositions. Conductivity measurements as a function of temperature as well as average grain size and crystallographic texture measurements were performed. The results indicate that the films deposited with the assistance of a plasma were amorphous at deposition temperatures of 650° C and below and polycrystalline at deposition temperatures of 700° C and above. In the temperature regime investigated, this amorphous-to-crystalline transition was not observed in films deposited without the assistance of a plasma. Furthermore, all the films deposited at temperatures of 650° C and below have been found to have significantly different properties from the similarly prepared films deposited at higher temperatures.     

用多晶硅吸杂和SiO2背封工艺提高硅片质量

我们对多晶硅吸荣和SiO_2背封二种工艺进行了系统的深入的实用性研究，解决了VLSI用外延片衬底的关键技术，提高了硅片质量并实现产业化。多晶硅每炉可生长约100mm（4英寸）硅片150～300片，SiO~2每炉生长100片。由于硅片质量好，工艺稳定，硅片已远销国外。     

半绝缘多晶硅薄膜的钝化与性能研究

通过LPCVD的方法,在Si基体表面制备了掺氧半绝缘多晶硅薄膜(SIPOS),分析了钝化机理,讨论了不同流量比与沉积速率、含氧量的关系以及SIPOS膜的含氧量对膜系结构、电阻率、折射率的性能影响,获得了最佳钝化条件,测试结果表明SIPOS薄膜晶体管击穿电压高、可靠性好、性能更稳定,可以满足现代生产的需要.     

Progress in 4H-SiC homoepitaxial growth by hot-wall LPCVD

Recent progress in 4H-SiC homoepitaxial growth by using hot-wall low-pressure chemical vapor deposition (HW-LPCVD) at the authors' group was reviewed. Horizontal air-cooled low-pressure hot-wall CVD (LPHWCVD) system was developed and employed to get high quality 4H-SiC epilayers. Homoepitaxial growth of 4HSiC on off-oriented Si-face (0001) substrates was performed at a typical temperature of 1 500 ℃ by using the stepcontrolled epitaxy. The typical growth rate was controlled to be about 1.0 μm/h. The background doping was reduced to 2 × 1015- 5 × 1015 cm-3. The FWHM of the rocking curve was 0 308 nm in 2 μm× 2 μm scale. Intentional N-doped and B-doped 4H-SiC epilayers were obtained by in-situ doping of NH3 and B2 H6, respectively. Thermal oxidization of 4H-SiC homoepitaxial layers was conducted in a dry O2 and H2 atmosphere at 1 150 ℃ and 4H-SiC MOS structures was obtained. Schottky barrier diodes with reverse blocking voltage of over 1000 V were achieved preliminarily.     

减压法制备TIO2薄膜的研究

主要研究了减压法制备 Ｔ Ｉ Ｏ２ 薄膜过程中氧气及水的变化对薄膜沉积率的影响; 对 Ｔ Ｉ Ｏ２ 薄膜生长反应动力学进行了研究。为制备优制 Ｔ Ｉ Ｏ２ 薄膜奠定了基础。     

SIPOS薄膜工艺及其稳定性研究

SIPOS半绝缘多晶硅薄膜在分立式器件特别是一些高压器件的钝化中有着广泛的应用,其不仅能够提升器件的反向击穿电压,而且也极大地提高了器件的可靠性。文章阐述了SIPOS薄膜的器件钝化机理,工艺过程中各参数对薄膜特性及应用的影响。同时通过实验设计DOE对LPCVD（化学气相沉积）系统的各个参数进行工程实验,分析了相关参数对薄膜沉积速率及特性的影响,并通过对实验结果的模型推导,得出相关工艺参数与产品电学性能之间的关系实验模型,并进一步阐述了工艺稳定性控制的方法,为SIPOS薄膜在工艺的实际工程应用中以及工艺的稳定性控制上提供可靠的技术支持。