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Proceedings Paper

Evaluation of Hitachi CAD to CD-SEM metrology package for OPC model tuning and product devices OPC verification
Author(s): Pietro Cantu; Gianfranco Capetti; Chiara Catarisano; Fabrizio D'Angelo; Elena Evangelista; Ermes Severgnini; Silvia Trovati; Mauro Vasconi; Takumichi Sutani; Stephan Wahl; Robert Steffen
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Paper Abstract

Optical proximity corrections are widely used in semiconductor industry to compensate non-linear effects occurring when printing features smaller than exposure wavelength. Most advanced OPC software packages simulate optical behavior starting from a physical description of illumination and projection optics, while the characterization of resist development and etch loading effects is still performed empirically, with different approaches that, generally, require the collection of a huge amount of experimental data. Due to the wide variety of target patterns, which makes conventional CD-SEM recipe creation impossible, critical dimension (CD) measurements are usually performed manually, requiring long time and, despite the attention paid while measuring, with poor guarantee of repeatability. The introduction of 193nm resists, much more sensitive to SEM e-beam exposure if compared to 248nm materials, required increased attention to be paid on both focusing and measuring phases in order to obtain reliable results. As well as OPC model tuning, the verification of correction effectiveness on product devices is performed almost in the same way leading to the same kind of issues. In order to overcome most of these problems ST is evaluating a new CD metrology package from Hitachi High Technologies; this tool allows fully automatic CD measurements starting from GDS II coordinate input. The exact recognition of measurement locations is obtained through an algorithm, based on the superposition of the drawn GDS II layout to the SEM wafer images, which allows achieving high positioning accuracy. The introduction of the tool significantly reduces measuring time down to the range of normal automated CD measurement times, while guarantying improved repeatability and optimized conditions even with 193nm resists due to the possibility of defining different structures for addressing and focusing before the measurement. This new system opens new perspectives in OPC modeling giving the opportunity of a more accurate model tuning, required by 65 nm technology node, and enables an extensive product devices OPC verification presently impossible due to time and procedure issues.

Paper Details

Date Published: 10 May 2005
PDF: 12 pages
Proc. SPIE 5752, Metrology, Inspection, and Process Control for Microlithography XIX, (10 May 2005); doi: 10.1117/12.601909
Show Author Affiliations
Pietro Cantu, STMicroelectronics (Italy)
Gianfranco Capetti, STMicroelectronics (Italy)
Chiara Catarisano, STMicroelectronics (Italy)
Fabrizio D'Angelo, STMicroelectronics (Italy)
Elena Evangelista, STMicroelectronics (Italy)
Ermes Severgnini, STMicroelectronics (Italy)
Silvia Trovati, STMicroelectronics (Italy)
Mauro Vasconi, STMicroelectronics (Italy)
Takumichi Sutani, Hitachi High-Technologies Co. (Japan)
Stephan Wahl, Hitachi High-Technologies Europe GmbH (Germany)
Robert Steffen, Hitachi High-Technologies Europe GmbH (Germany)

Published in SPIE Proceedings Vol. 5752:
Metrology, Inspection, and Process Control for Microlithography XIX
Richard M. Silver, Editor(s)

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