Product Briefing Outline:
Brion Technologies, a division of ASML, has launched a new product for its Tachyon computational lithography platform. Tachyon MB-SRAF (Model-Based Sub-Resolution Assist Features) is said to enable the high-speed, full-chip processing of advanced chip designs with larger process windows, greater productivity, and lower development costs than rule-based alternatives.
As chip geometries shrink to ever-smaller sizes the ability to image the design properly depends on resolution enhancement techniques (RET) such as sub-resolution assist features which are not part of the original design. These assist features do not print, but aid in the proper imaging of the intended pattern. The application of SRAFs provides a larger process window, giving greater latitude in imaging and resulting in higher yielding devices. Model-based SRAF techniques have been in development for some time but until now have not been used for full-chip applications due to heavy compute costs, poor quality of correction, and/or the extreme impact to mask costs from the pixelated geometries they generate.
The industry-wide adoption of freeform illumination enabled by ASML’s FlexRay technology and Brion’s Tachyon SMO (source mask optimization) software further challenges the limitations of rule-based SRAF technology. To realize FlexRay illuminator performance and at the same time make the solution robust against all pattern proximities and layout variations, there is an explosion in the necessary number of rules governing SRAF shape, size and placement. Development times for rule-based SRAFs are thus increasing dramatically and require many iterations of mask tape-out and wafer print tests. In particular, compute times for Tachyon MB-SRAF have been substantially reduced to enable cost-effective full-chip processing, and are typically comparable with the corresponding OPC compute times on the same layer. Tachyon MB-SRAF is said to be essential for patterning 2D layers in next generation processes at the 2x nm nodes and beyond.
Freeform source mask optimization and full chip MB-SRAF (Model-Based Sub-Resolution Assist Features).
The Tachyon MB-SRAF recipe can be developed and optimized in a fraction of this time and cost, in much the same way that model-based OPC has proven superior to rule-based OPC.
September, 2011 onwards.