标题: | 复晶矽薄膜之结晶成长与杂质活化及复晶矽薄膜电晶体特性之研究 Recrystallization and Dopant Activation of LPCVD Silicon Films and the Characterization of Poly-Si Thin Film Transistors |
作者: | 蔡孟锦 Meng-Jin Tsai 郑晃忠 Huang-Chung Cheng 电子研究所 |
关键字: | 非晶矽,复晶矽,杂质活化,薄膜电晶体;amorphous-Si, poly-Si,dopant activation,thin-film transistor |
公开日期: | 1994 |
摘要: | 在本论文中,我们探讨了复晶矽薄膜之结晶成长,植入离子的活化机构,并 探讨了复晶矽薄膜电晶体的电特性与钝化技术.在低温炉管退火下,非晶矽 薄膜可获致比复晶矽薄膜较大的晶粒.这是因为非晶矽薄膜在结晶过程中 有较少的成核中心,故可以得到较大的晶粒.当雷射功率足以熔融矽薄膜 时,结晶进入液相晶粒成长的机构,此时,不论是非晶或多晶矽薄膜,都可获 致极大的成长晶粒.在植入离子的活化研究中,对于不同的活化温度,我们 发现砷搀杂试片之片电阻在退火温度介于 650~850 ℃ 之间会随着退火温 度的增加而上升.这种逆向热退火(reverse annealing)的现象主要是由于 活化离子扩散到晶界析出(segregation)的结果.对于低温活化 P-型搀杂 的试片,二氟化硼搀杂的试片,其中的氟离子俱备填补晶格缺陷的功能,在 低温活化N-型搀杂试片的研究中,我们发现晶粒成长的孕育期会随布值浓 度的增加而延长.对于磷,砷布植的试片,适当的搀剂量会促进晶粒成长.但 是过高的布值剂量则会造成布植离子丛聚(cluster formation),阻碍晶界 向外扩长,造成较小的成长晶粒.在氢/氮电浆钝化处理方面,我们发现添加 氮气的氢化处理可获致比传统氢气电浆钝化更佳的电性提升.最后,本论文 又提出一种双通道复晶矽薄膜电晶体之新型结构.在传统通道区域内加入 一层薄的埋藏介电质,可以降低垂直电场强度,减少载子散射机率,得到比 传统结构更高的等效移动率及电流趋动力.此外,我们也发现一种奇特的双 电晶体特性,这是由于上层通道累增崩溃造成电荷累积进而引发下层通道 导通的结果.此种双通道电晶体特性将可应用在多元逻辑及控制电路等用 途上. In this thesis, the grain growth mechanisms of low-pressure chemical vapor deposition (LPCVD) silicon films, the dopant activation of implanted ions in poly-Si layers,and the electrical characteristics as well as the passivation effects of the poly- Si thin film transistors (poly-Si TFTs) have been investigated. The lower density of nuclei formation of the a-Si layer could result in the larger final grain size. Significant large grain sizes can be achieved for large laser powers.An increase in sheet resistance have been observed for the As+- implanted specimens within the annealing temperature ranging from 650 to 850 ℃. For the BF2+-implanted specimens, the fluorine ions can passivate the trap states.Too high of the doping level may cause the dopant cluster formation for the N- type dopants. Which will inhibit the expansion of grain boundaries. For the H2/N2 plasma passivation, the nitrogen- containing hydrogen (H2/N2) plasma treatments show better passivation effects on the electrical characteristics of the poly-Si TFTs than the pure H2 hydrogenation. The vertical electrical field can be reduced by inserting a thin buried oxide within the traditional channel region and the higher effective mobility as well as the larger drivability can be achieved for the DAL poly-Si TFTs. |
URI: | http://140.113.39.130/cdrfb3/record/nctu/#NT830430027 http://hdl.handle.net/11536/59211 |
显示于类别: | Thesis |