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23 March 2009 Advanced modeling strategies to improve overlay control for 32-nm lithography processes
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Overlay control is gaining more attention in recent years as technology moves into the 32nm era. Strict overlay requirements are being driven not only by the process node but also the process techniques required to meet the design requirements. Double patterning lithography and spacer pitch splitting techniques are driving innovative thinking with respect to overlay control. As lithographers push the current capabilities of their 193nm immersion exposure tools they are utilizing newly enabled control 'knobs'. 'Knobs' are defined as the adjustment points that add new degrees of freedom for lithographers to control the scanner. Expanded control is required as current scanner capabilities are at best marginal in meeting the performance requirements to support the ever demanding process nodes. This abstract is an extension of the SPIE 2008 paper in which we performed thorough sources of variance analysis to provide insight as to the benefits of utilizing high order scanner control knobs [1]. The extension this year is to expand the modeling strategies and to validate the benefit through carefully designed experiments. The expanded modeling characterization will explore not only high order correction capabilities but also characterize the use of field by field corrections as a means to improve the overlay performance of the latest generation of immersion lithography tools. We will explore various correction strategies for both grid and field modeling using KT AnalyzerTM.
© (2009) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Anna Minvielle, Lovejeet Singh, Jeffrey Schefske, Joerg Reiss, Eric Kent, Terry Manchester, Brad Eichelberger, Kelly O'Brien, Jim Manka, John C. Robinson, and David Tien "Advanced modeling strategies to improve overlay control for 32-nm lithography processes", Proc. SPIE 7272, Metrology, Inspection, and Process Control for Microlithography XXIII, 72722X (23 March 2009);

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