Raised source/drain (Rsd) and vertical lightly doped drain (LDD) poly-Si thin-film transistor

Feng Tso Chien, Jing Ye, Wei Cheng Yen, Chii Wen Chen, Cheng Li Lin, Yao Tsung Tsai

Research output: Contribution to journalArticlepeer-review

3 Scopus citations

Abstract

The raised source/drain (RSD) structure is one of thin film transistor designs that is often used to improve device characteristics. Many studies have mentioned that the high impact ionization rate occurring at a drain side can be reduced, owing to a raised source/drain area that can disperse the drain electric field. In this study, we will discuss how the electric field at the drain side of an RSD device is reduced by a vertical lightly doped drain (LDD) scheme rather than a RSD structure. We used different raised source/drain forms to simulate the drain side electric field for each device, as well as their output characteristics, using Integrated Systems Engineering (ISE-TCAD) simulators. Different source and drain thicknesses and doping profiles were applied to verify the RSD mechanism. We found that the electric fields of a traditional device and uniform doping RSD structures are almost the same (~2.9 × 105 V/cm). The maximum drain electric field could be reduced to ~2 × 105 V/cm if a vertical lightly doped drain RSD scheme was adopted. A pure raised source/drain structure did not benefit the device characteristics if a vertical lightly doped drain design was not included in the raised source/drain areas.

Original languageEnglish
Article number103
Pages (from-to)1-11
Number of pages11
JournalMembranes
Volume11
Issue number2
DOIs
StatePublished - Feb 2021

Keywords

  • Kink effect
  • Lightly doped drain (LDD)
  • Raised source/drain (RSD)
  • Thin film transistor (TFT)

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