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Method of Modeling and Enabling FinFET Diffusion Resistance

IP.com Disclosure Number: IPCOM000239169D
Publication Date: 2014-Oct-19
Document File: 4 page(s) / 240K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for Field Effect Transistor (finFET) modeling for finFET diffusion resistance for various layouts and various switching cases in a Simulated Program with Integrated Circuit Emphasis (SPICE) model.

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Method of Modeling and Enabling FinFET Diffusion Resistance

A method is needed to model and enable fin Field Effect Transistor (finFET) diffusion resistance for various layouts and various switching cases in a Simulated Program with Integrated Circuit Emphasis (SPICE) model.

One existing method uses a model instance parameter to distinguish between a shared diffusion layout and an un-shared diffusion layout (Figure 2). Even for a shared diffusion case, two shared FETs may not be switched at a same time. The "fixed R" approach cannot accurately handle this dynamic case. It also does not correctly handle the layout case of stacked FETs (also called merged diffusion region). This will give an inaccurate simulation results for "Not And" (NAND) (Figure 3) and "Not Or" (NOR) circuits.

Disclosed herein is an improved modeling method. It puts less resistance (−R ) in FET's I-V curves and puts more resistance (R ) in a diffusion resistance model for FET's source/drain regions (Figure 1).

Figure 1: finFET model fitting

The implementation of the finFET model fitting method comprises:

1. Simulate/measure finFET I-V curves extensively for an unshared CA layout. Include drain current under an over-drive, linear condition (say, Vds = 50 mV and Vgs = Vtlin + 0.7 V) and obtain R od,lin (= R on) for this layout [denote it as R 1(T )]

2. Simulate/measure finFET drain current under the over-drive, linear condition for a corresponding shared CA layout under a same drain current condition and obtain Rodlin for this case [denote it as R2(T)]


3. Find the difference between two diffusion resistances. Per diffusion, it is

R (T) = [R 2(T ) - R 1(T )]/2. [∆R (T) > 0]


4. Fit a finFET model to the I-V curves in unshared CA case (obtained in step 1).

After finFET model fitting, make each of...