Microelectronic Engineering 70 (2003) 83–92 www.elsevier.com / locate / mee Two-dimensional model for investigating body contact structures in PD SOI MOSFETs * Arash Daghighi , Mohamed A. Osman School of Electrical Engineering and Computer Science, Washington State University, ElecMech 102, Spokane Street, Pullman, WA 99164-2752, USA Received 22 January 2003; received in revised form 9 June 2003; accepted 9 June 2003 Abstract A two-dimensional (2-D) model for investigating body tied to source (BTS) contacts in PD SOI MOSFETs is presented. The model simulates a 2-D cross-section parallel to the gate in a region close to back oxide of BTS PD SOI MOSFET. Optical generation was used in the simulation program to describe the hole generation via impact ionization and thermal generation. By using this method, holes in the depletion region at the body–drain junction was introduced into the neutral body region and accounts for the different hole generation rates in the active and inactive parts of the BTS PD SOI MOSFET. The model is used for simulating three different body contact structures. Simulations using the model confirms reduction in floating body voltage by using body contacts and shows that narrow body contacts are as effective as wide body contacts.  2003 Elsevier B.V. All rights reserved. Keywords: PD SOI MOSFET; Body contact; Two-dimensional device model; Floating body voltage 1. Introduction ing low electric field, high trans-conductance, re- duced short channel effects and steep sub-threshold Recently, there has been a growing interest in slopes. However, the threshold voltage of FD SOI is using Silicon on Insulator (SOI) MOSFET for high highly sensitive to the silicon film thickness demand- speed digital and RF circuits because it offers a ing precise control of thickness. On the other hand, 20–35% performance gain over Bulk CMOS [1]. PD SOI processes scale well to smaller dimensions. Some of the advantages are reduced junction capaci- The presence of buried oxide layer results in a tance, full isolation of the neighboring devices, floating body region and the low thermal conduc- elimination of the latch up, reduction of the leakage tivity of SiO layer causes self heating effects [3]. 2 current and better short channel effects [2]. Fully Additionally, because of the floating body, SOI depleted (FD) SOI has the best performance includ- devices exhibit premature bipolar conduction relative to bulk silicon devices which coupled with the increase in the body voltage causes the kink seen in *Corresponding author. Tel.: 11-509-335-1846; fax: 11-509- the output characteristics of partially depleted (PD) 335-3818. SOI n-MOSFETs [2]. E-mail addresses: adaghigh@eecs.wsu.edu (A. Daghighi), osman@eecs.wsu.edu (M.A. Osman). Several approaches have been proposed to mini- 0167-9317 / 03 / $ – see front matter  2003 Elsevier B.V. All rights reserved. doi:10.1016 / S0167-9317(03)00397-6