Double patterning from design enablement to verification

摘要

Litho-etch-litho-etch (LELE) is the double patterning (DP) technology of choice for 20 nm contact, via, and lower metal layers. We discuss the unique design and process characteristics of LELE DP, the challenges they present, and various solutions. 1.We examine DP design methodologies, current DP conflict feedback mechanisms, and how they can help designers identify and resolve conflicts. 2. In place and route (P&R), the placement engine must now be aware of the assumptions made during IP cell design, and use placement directives provide by the library designer. We examine the new effects DP introduces in detail routing, discuss how multiple choices of LELE and the cut allowances can lead to different solutions, and describe new capabilities required by detail routers and P&R engines.3. We discuss why LELE DP cuts and overlaps are critical to optical process correction (OPC), and how a hybrid mechanism of rule and model-based overlap generation can provide a fast and effective solution. 4. With two litho-etch steps, mask misalignment and image rounding are now verification considerations. We present enhancements to the OPCVerify engine that check for pinching and bridging in the presence of DP overlay errors and acute angles.