Comparison of poly-Si films deposited by UHVCVD and LPCVD and its application for thin film transistors

D. Z. Peng*, Hsiao-Wen Zan, P. S. Shih, T. C. Chang, C. W. Lin, C. Y. Chang

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

4 Scopus citations

Abstract

The ultra-high vacuum chemical vapor deposition (UHVCVD) system can deposit poly-Si film without any laser or furnace annealing. The uniformity of threshold voltage and mobility is superior to that deposited by low-pressure chemical vapor deposition (LPCVD) system. However, due to the deposition in polycrystalline phase for UHVCVD, the film surface is rough and results in low field effect mobility compared to that obtained by LPCVD using disilane (Si2H6) in amorphous phase followed by solid phase crystallization (SPC). The on-off current ratio for UHVCVD deposited poly-Si thin film transistors (TFTs) is approximately one order smaller, however, the leakage current for LPCVD SPC TFTs is higher. In this experiment, NH3 was introduced to both of the two samples to improve the device performance. It can be shown that improvements on device characteristics are more significant for UHVCVD deposited poly-Si TFTs, e.g. threshold voltage decreased dramatically and the on-off current ratio improved by two orders of magnitude.

Original languageEnglish
Pages (from-to)641-645
Number of pages5
JournalVacuum
Volume67
Issue number3-4
DOIs
StatePublished - 26 Sep 2002

Keywords

  • Low-pressure chemical vapor deposition (LPCVD)
  • Plasma passivation
  • Poly-Si
  • Solid phase crystallization (SPC)
  • TFT
  • Ultra-high vacuum chemical vapor deposition (UHVCVD)

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