Die-to-database verification tool for detecting CD errors, which are caused by OPC features, by using mass gate measurement and layout information

With the shrinking of device sizes, the issue of controlling gate critical dimension (CD) is becoming increasingly important. In particular, the ability to find systematic defects and use that information in the design, optical proximity correction (OPC), and mask creation phases is becoming critical to improving circuit yield. Current critical dimension electron scanning microscopes (CD-SEMs) and macro inspection systems, however, fail to address this area in a practically usable manner - with CD-SEMs limited by their low throughput, and macro inspection systems limited by their low resolution. The NGR2100 die-to-database verification system introduces high-throughput, wide field of view (FOV) electron beam scanning technology to allow for mass gate measurement and analysis. Using the collected data combined with layout data and statistical analysis, the NGR2100 system categorizes and outputs the systematic CD errors existing on a wafer, which can be fed back to the design, OPC, and mask creation phases for true design-for-manufacturing (DFM) realization. This paper provides an overview of the NGR2100, the process involved for gate CD error detection, and presents an actual case in which the NGR2100 was used to collect and analyze data for a memory device.