An analytical threshold-voltage model of trench-isolated MOS devices with nonuniformly doped substrates

A simple closed-form expression of the threshold voltage is developed for trench-isolated MOS (TIMOS) devices with feature size down to the deep-submicrometer range. The analytical expression is the first developed to include the nonuniform doping effect of a narrow-gate-width device. The inverse narrow width effect can be predicted analytically from the proposed model. It was derived by modeling the gate sidewall capacitance to include the two-dimensional field-induced edge fringing effect and solving the Poisson equation to include the channel implant effect at different operating backgate biases. A two-dimensional simulation program was developed, and the simulated data were used for verification of the analytical model. Good agreements between the modeled and simulated data have been achieved for a wide range of gate widths and biases. The model is well suited for the design of the basic transistor cell in DRAM circuits using trench field oxide isolation structure. >

[1]  K. Hong,et al.  An analytical model for the inverse narrow‐gate effect of a metal‐oxide‐semiconductor field‐effect transistor , 1987 .

[2]  K.N. Bhat,et al.  The correct equivalent box representation for the buried layer of BC MOSFET's in terms of the implantation parameters , 1987, IEEE Electron Device Letters.

[3]  T. Shibata,et al.  A new bird's-beak free field isolation technology for VLSI devices , 1981, 1981 International Electron Devices Meeting.

[4]  Kuang Yi Chiu,et al.  A bird's beak free local oxidation technology feasible for VLSI circuits fabrication , 1982 .

[5]  N. Shigyo,et al.  Analysis of an Anomalous Subthreshold Current in a Fully Recessed Oxide MOSFET Using a Three-Dimensional Device Simulator , 1985, IEEE Journal of Solid-State Circuits.

[6]  Chih-Tang Sah,et al.  Threshold voltage models of the narrow-gate effect in micron and submicron MOSFETs , 1988 .

[7]  L. Akers,et al.  The inverse-narrow-width effect , 1986, IEEE Electron Device Letters.

[8]  L. A. Akers,et al.  Inverse-narrow-width effects and small-geometry MOSFET threshold voltage model , 1988 .

[9]  Lex A. Akers,et al.  Threshold voltage models of short, narrow and small geometry MOSFET's: A review , 1982 .

[10]  S. Karmalkar,et al.  A process-parameter-based circuit simulation model for ion-implanted MOSFETs and MESFETs , 1989 .

[11]  S. Selberherr.  Analysis and simulation of semiconductor devices , 1984 .

[12]  S.S.-S. Chung.  A complete model of the I-V characteristics for narrow-gate MOSFETs , 1990 .

[13]  E. H. Li,et al.  The narrow-channel effect in MOSFET's with semi-recessed oxide structures , 1990 .

[14]  F.Z. Custode,et al.  A model of a narrow-width MOSFET including tapered oxide and doping encroachment , 1981, IEEE Transactions on Electron Devices.