Pattern based mask process correction: impact on data quality and mask writing time

Abstract

The continuous drive of the semiconductor industry towards smaller features sizes requires mask manufacturers to achieve ever tighter tolerances for the most critical dimensions on the mask. CD uniformity requires particularly tight control. Equipment manufacturers and process engineers target their development to support these requirements. But as numerous publications indicate, more sophisticated data correction methods are still employed to compensate for shortcomings in equipment and process or to account for the boundary conditions in some layouts that contribute to process deviations. Among the corrected effects are proximity and linearity effects, fogging and etch effects, and pattern fidelity. Different designs vary by pattern size distribution as well as by pattern density distribution. As the implementation of corrections for optical proximity effects in wafer lithography has shown, breaking up the original polygons in the design layout for selective and environment-aware correction yields increased data volumes and can have an impact on the data quality of the mask writing data. The paper investigates the effect of various correction algorithms specifically deployed for mask process effects on top of wafer process related corrections. The impact of MPC flows such as rule-based linearity and proximity correction and density-based long range effect correction on the metrics for data preparation and mask making is analyzed. Experimental data on file size, shot count and data quality indicators including small figure counts are presented for different correction approaches and a variety of correction parameters.

Model based mask process correction and verification for advanced process nodes

“…The flow includes the data collection with a test reticle, the model building, correction recipe generation, correction, verification recipe generation and verification as well as the results assessment. Prior work has established a framework to describe short-range etch effects in mask etch [13] and data processing methods for shape based correction [14,15]. In a previous publication a modeling flow capturing both long-range and short-range mask process effects was presented [1].…”

Extreme long range process effects characterization and compensation

“…Long range effects and extreme long range effects such as fogging have long been addressed with various techniques [11], [12]. Moreover, we have already demonstrated [13] the use of pattern density across the full range of a reticle field influencing final PEC using a PSF dedicated for extreme long range effects.…”

Advanced mask process modeling for 45-nm and 32-nm nodes

“…Previous work has established a framework to describe short-range etch effects in mask etch [8]. The correction technology for density driven long-range process effects has also been developed and characterized [9,10]. A modeling flow capturing both long-range and short-range mask process effects are presented here as a precursor to subsequent model-based mask pattern correction and correction verification.…”