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Proceedings Paper

Variable-threshold optical proximity correction (OPC) models for high-performance 0.18-um process
Author(s): Hongmei Liao; Shane R. Palmer; Kayvan Sadra
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Paper Abstract

The recent development of lithographic resolution enhancement techniques of optical proximity correction (OPC) and phase shift masks (PSM) enable sprinting critical dimension (CD) features that are significantly smaller than the exposure wavelength. In this paper, we present a variable threshold OPC model that describes how a pattern configuration transfers to the wafer after resist and etch processes. This 0.18 micrometers CMOS technology utilizes isolation with pitches of active device regions below 0.5 micrometers . The effective gate length on silicon is in the range of 0.11 to 0.18 micrometers . The OPC model begins with a Hopkin's formula for aerial image calculation and is tuned to fit the measured CD data, using a commercially available software. The OPC models are anchored at a set of selected CD dat including linearity, line-end pullback, and linewidth as a function of pitch. It is found that the threshold values inferred from measured CD dat vary approximately linearly with the slope of aerial image. The accuracy of the model is illustrated by comparing the simulated contour using the OPC model and measured SEM image. The implementation of OPC models at both active and gate is achieved using two approaches: (1) to optimize the mask bias and sizes of hammerhead and serifs via a rule based approach; and (2) to correct the SRAM cell layouts by OPC model. The OPC models developed have been successfully applied to 0.18 micrometers technology in a prototyping environment.

Paper Details

Date Published: 5 July 2000
PDF: 8 pages
Proc. SPIE 4000, Optical Microlithography XIII, (5 July 2000); doi: 10.1117/12.388938
Show Author Affiliations
Hongmei Liao, Texas Instruments Inc. (United States)
Shane R. Palmer, Texas Instruments Inc. (United States)
Kayvan Sadra, Texas Instruments Inc. (United States)

Published in SPIE Proceedings Vol. 4000:
Optical Microlithography XIII
Christopher J. Progler, Editor(s)

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