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

The Korea Institute of Information and Commucation Engineering (한국정보통신학회)
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The impact of substrate bias on the Z-RAM characteristics in n-channel junctionless MuGFETs

기판 전압이 n-채널 무접합 MuGFET 의 Z-RAM 특성에 미치는 영향

  • Lee, Seung-Min (Department of Electronics Engineering, Incheon National University) ;
  • Park, Jong-Tae (Department of Electronics Engineering, Incheon National University)
  • Received : 2014.03.17
  • Accepted : 2014.04.22
  • Published : 2014.07.31
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Abstract

In this paper, the impact of substrate bias($V_{BS}$) on the zero capacitor RAM(Z-RAM) in n-channel junctionless multiple gate MOSFET(MuGFET) has been analyzed experimentally. Junctionless transistors with fin width of 50nm and 1 fin exhibits a memory window of 0.34V and a sensing margin of $1.8{\times}10^4$ at $V_{DS}=3.5V$ and $V_{BS}=0V$. As the positive $V_{BS}$ is applied, the memory window and sensing margin were improved due to an increase of impact ionization. When $V_{BS}$ is increased from 0V to 10V, not only the memory window is increased from 0.34V to 0.96V but also sensing margin is increased slightly. The sensitivity of memory window with different $V_{BS}$ in junctionless transistor was larger than that of inversion-mode transistor. A retention time of junctionless transistor is better than that of inversion-mode transistor due to low Gate Induced Drain Leakage(GIDL) current. To evaluate the device reliability of Z-RAM, the shifts in the Set/Reset voltages and current were measured.

본 연구에서는 다중게이트 구조인 n-채널 무접합(junctionless) MuGFET 의 기판 전압이 zero capacitor RAM(Z-RAM) 특성에 미치는 영향에 대하여 실험적으로 분석하였다. 핀 폭이 50nm 이고, 핀 수가 1인 무접합 트랜지스터의 드레인에 3.5V, 기판에 0V 가 인가된 경우, 메모리 윈도우는 0.34V 이며 센싱 마진 은 $1.8{\times}10^4$ 의 특성을 보였다. 양의 기판 전압이 인가되면 충격 이온화가 증가하여 메모리 윈도우와 센싱 마진 특성이 개선되었다. 기판 전압이 0V에서 10V로 증가함에 따라, 메모리 윈도우 값은 0.34V 에서 0.96V 로 증가하였고, 센싱 마진 또한 소폭 증가하였다. 기판 전압에 따른 무접합 트랜지스터의 메모리 윈도우 민감도가 반전 모드 트랜지스터 보다 큰 것을 알 수 있었다. Gate Induced Drain Leakage(GIDL) 전류가 작은 무접합 소자의 경우 반전모드 소자에 비해서 보유시간 특성이 좋을 것으로 사료된다. Z-RAM의 동작 신뢰도 평가를 위해서 셋/리셋 전압 및 전류의 변화를 측정하였다.

Keywords

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