APCVD法在硅基板上制备硅化钛纳米线

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摘   要
跨入21世纪随着平板显示技术（FPD）飞速发展，需要更低电阻率的材料作为FPD薄膜晶体管的接触电极，以提高响应速率、降低功耗。传统的场致发射平板显示器（FED）的微尖锥场发射体制作成本高、易与环境气体反应，限制了其工业化。采用低成本的方法在基板上制备高导电性的硅化钛薄膜并在薄膜层上生长纳米线能够有效的解决这些问题，极大的推动平板显示技术进一步发展。
本论文采用常压化学气相沉积法(APCVD)以SiH4和TiCl4为前驱体在硅板/玻璃衬底上一次性制备出大面积硅化钛薄膜/纳米线复合结构，运用XRD、SEM、TEM等手段对样品的结构和性能进行了测试和分析。讨论了晶相的形成过程和机理，以及薄膜层上纳米线的形成和生长机理。成功实现了硅化钛纳米线在相应薄膜层上的生长。
结果表明，APCVD法在基板上沉积低电阻硅化钛（TiSi2）的过程由前驱体SiH4 和TiCl4的化学反应控制。通过调制前驱体不同的反应进程，使生成TiSi2的化学反应在沉积过程中为主导，促进TiSi2晶相的形成，从而得到电阻率较低的薄膜和纳米线，典型样品的电阻率为37μΩ·cm。TiSi2在基板上的形成过程是，SiH4 和TiCl4在气相反应直接形成TiSi2晶核，而后沉积在衬底的表面，随着沉积时间的延长，晶粒逐渐长大，堆积变得致密，结构也趋于完整，薄膜的电阻率也随着降低。
APCVD法成功的在基板上一次性制备出大面积硅化钛薄膜/纳米线复合结构，实现了高质量的硅化钛纳米线在薄膜层上的生长。正交晶系的TiSi圆形纳米线，长约几微米，直径约20nm。纳米线可能以气/固模式生长，在硅片下面的玻璃上同样生长出来了相同尺寸的TiSi纳米线，纳米线的生长与基体无太大关系。
关键词：APCVD 硅化物 晶相形成 纳米线 TiSi2 TiSi

ABSTRACT
The Flat Panel Displays (FPDs) are rapidly developing in 21st century. Novel materials with the lower resistivity are required for contact electrodes of the FPDs to enhance the respond performance. Besides, Fabrication of the field-emitters of Field Emission Displays (FEDs) is too complex to step forward. The combination of conductive thin films and nanowires deposited on large area substrate by simple methods with low cost will solve the above problems.
   In this thesis, the films and nanowires of titanium silicides were prepared on the substrate by atmosphere pressure chemical vapor deposition (APCVD), using SiH4 and TiCl4 as precursors. XRD, FESEM were employed to characterize structure and properties of the NWs/films, respectively. The phase formation in the NWs and CVD reaction were studied. The formation and growth of TiSi nanowires were also clarified, and successfully prepared nanowires on the respective film.
   The results reveal that the deposition of the films is determined by CVD reaction between SiH4 and TiCl4.Via controlling the CVD reaction to promote the TiSi2 formation, the TiSi2 can be gained with the low resistivity. The mechanism of the films deposition is described as below: SiH4 and TiCl4 directly reacted in the vapor phase at first, and then the TiSi2 grains deposited on the substrate. The stack density of the TiSi2 crystalline phase gradually increased and the particles grew up. The films came to continuous and uniform, resulting in the low resistivity.
   The TiSi crystalline nanowires/film structure were largely prepared on the substrate, and gained high quality TiSi nanowires on the film. The length of the nanowires is more than several micrometers with the orthorhombic structure, and the diameter is 20nm. The growth process may be the ‘vapor-solid’ (VS) growth mode, on the glass substrate under the Si, we also gained the same size TiSi nanowires. The substrate almost has nothing to do with the growth of the nanowires.

Keywords: APCVD  Silicide  phase formation  nanowires TiSi2  TiSi

目  录
摘要 
ABSTRACT  II
目录 
第一章文献综述  1
1.1 金属硅化物  1
常用的难熔金属硅化物  2
1.2硅化钛  3
1.2.1硅化钛的组成  3
1.2.2 TiSi2的优点  4
1.2.3沉积方法  4
1.2.3.1 CVD技术沉积硅化钛  4
1.2.3.1.1 常压化学气相沉积（APCVD  5
1.2.3.1.2 低压化学气相沉积（LPCVD  7
1.2.3.1.3 等离子激发化学气相沉积（PECVD  7
1.2.3.1.4 激光诱导化学气相沉积（LICVD 8
1.2.3.2金属有机物化学气相沉积(MOCVD  8
1.3金属硅化物纳米线  9
1.3.1纳米材料的特性  9
1.3.1.1 量子尺寸效应  9
1.3.1.2 宏观量子隧道效应  10
1.3.1.3 库仑阻塞效应  10
1.3.1.4 小尺寸效应  11
1.3.1.5 表面效应  11
1.4 参考文献  12
第二章实验方法  13
2.1 APCVD硅化钛  13
2.1.1 APCVD硅化钛装置  13
2.1.2实验操作  14
2.2 测试设备及其原理  17
2.2.1 X射线衍射(XRD  17
2.2.2透射电子显微镜(TEM  18
2.2.3场发射扫描电镜(FESEM  19
2.2.4 电阻的测定  19
第三章实验结果及讨论  19
3.1 APCVD硅化钛薄膜在单晶硅衬底上的形成  20
  3.1.1硅基板上硅化钛薄膜样品的测试结果  20
3.1.2 硅化钛薄膜中各相形成机理的分析  21
3.2 APCVD硅化钛纳米线在单晶硅基板上的形成  22
3.2.1硅化钛纳米线的形成  22
3.2.2对硅化钛纳米线形成机理的分析  24
3.2.3硅化钛纳米线/膜复合结构的电阻率  28
实验经验  29
3.3本章小结  29
第四章结论  29
分析和结论  29
参考文献  30

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