Journal of the Korea Institute of Information and Communication Engineering (한국정보통신학회논문지)

The Korea Institute of Information and Commucation Engineering (한국정보통신학회)
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Subthreshold Current Model for Threshold Voltage Shift Analysis in Junctionless Cylindrical Surrounding Gate(CSG) MOSFET

무접합 원통형 게이트 MOSFET에서 문턱전압이동 분석을 위한 문턱전압이하 전류 모델

  • Jung, Hakkee (Department of Electronic Engineering, Kunsan National University)
  • Received : 2016.11.23
  • Accepted : 2016.12.23
  • Published : 2017.04.30
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Abstract

Subthreshold current model is presented using analytical potential distribution of junctionless cylindrical surrounding-gate (CSG) MOSFET and threshold voltage shift is analyzed by this model. Junctionless CSG MOSFET is significantly outstanding for controllability of gate to carrier flow due to channel surrounded by gate. Poisson's equation is solved using parabolic potential distribution, and subthreshold current model is suggested by center potential distribution derived. Threshold voltage is defined as gate voltage corresponding to subthreshold current of $0.1{\mu}A$, and compared with result of two dimensional simulation. Since results between this model and 2D simulation are good agreement, threshold voltage shift is investigated for channel dimension and doping concentration of junctionless CSG MOSFET. As a result, threshold voltage shift increases for large channel radius and oxide thickness. It is resultingly shown that threshold voltage increases for the large difference of doping concentrations between source/drain and channel.

본 논문에서는 무접합 원통형 MOSFET의 해석학적 전위분포를 이용하여 문턱전압이하 전류모델을 제시하고 이를 이용하여 문턱전압이동을 해석하였다. 무접합 원통형 MOSFET는 채널을 게이트 단자가 감싸고 있기 때문에 캐리어 흐름을 제어하는 게이트 단자의 능력이 매우 우수하다. 본 연구에서는 쌍곡선 전위분포모델을 이용하여 포아송방정식을 풀고 이 때 얻어진 중심 전위분포를 이용하여 문턱전압이하 전류 모델을 제시하였다. 제시된 전류모델을 이용하여 $0.1{\mu}A$의 전류가 흐를 때 게이트 전압을 문턱전압으로 정의하고 2차원 시뮬레이션 값과 비교하였다. 비교결과 잘 일치하였으므로 이 전류모델을 이용하여 채널크기 및 도핑농도에 따라 문턱전압이동을 고찰하였다. 결과적으로 채널 반지름이 증가할수록 문턱전압이동은 매우 크게 나타났으며 산화막 두께가 증가할 경우도 문턱전압이동은 증가하였다. 채널 도핑농도에 따라 문턱전압을 관찰한 결과, 소스/드레인과 채널 간 도핑농도의 차이가 클수록 문턱전압은 크게 증가하는 것을 관찰하였다.

Keywords

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