Material Representations and Algorithms for Nanometer Lithography Simulation

Edward W. SCHECKLER  Taro OGAWA  Shoji SHUKURI  Eiji TAKEDA  

Publication
IEICE TRANSACTIONS on Electronics   Vol.E77-C   No.2   pp.98-105
Publication Date: 1994/02/25
Online ISSN: 
DOI: 
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Issue on 1993 VLSI Process and Device Modeling Workshop (VPAD 93))
Category: Process Simulation
Keyword: 
lithography simulation,  pattern fluctuation PMMA,  SAL-601,  electron beam,  

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Summary: 
Material representations and algorithms are presented for simulation of nanometer lithography. Organic polymer resists are modeled as collections of overlapping spheres, with each sphere representing a polymer chain. Exposure and post-exposure bake steps are modeled at the nanometer scale for both positive and negative resists. The development algorithm is based on the Poisson removal probability for each sphere in contact with developer. The Poisson removal rate for a given sphere is derived from a mass balance relationship with a macroscopic development rate model. Simulations of electron beam lithography with (poly) methyl methacrylate and Shipley SAL-601 reveal edge roughness standard deviations from 2 to 3 nm, leading to linewidth peak-to-peak 3σ variation of 15 to 22 nm. Typical simulations require about 2 MBytes and under 5 minutes on a Sun Sparc 10/41 engineering workstation.