Scatterometry Feasibility Studies for 0.13-Micron Flash Memory Lithography Applications; Enabling Integrated Metrology

摘要

A series of experiments were performed to determine if the ThermaWave INTEGRA~(TM) CCDi reflectometer combined with Timbre Technologies' Optical Digital Profiler~(TM) (ODP) software could meet the requirements for lithography cell integration and process control of critical 0.13-micron Rash memory applications. Shallow Trench Isolation (STI), First Poly Gate, Stacked Gate and Aluminum Interconnect layers were examined as a part of this study. ODP models were developed for each of these applications and their output was compared to Critical Dimension Scanning Electron Microscopy (CDSEM) and cross-section SEM to demonstrate adequate correlation to incumbent metrology techniques. ODP is shown herein to correlate to CDSEM while providing the throughput required to measure every wafer without creating a bottleneck for the lithography cell. Experimental results also suggest that, in many cases, ODP can deliver profile determination beyond the fundamental capability of standard in-line metrology techniques.