San Jose, CA--In the last two decades, integrated-circuit (IC)-chip feature sizes have shrunk from a micron in width to one tenth that, and are still shrinking. Over that span of time, the Prolith lithography-optimization software tool has grown up with the industry, keeping up with (and aiding) advances in photoresists, photomasks, lithographic optics, and processing techniques.
KLA-Tencor's Prolith, which combines chemical, optical, and mechanical modeling of the lithographic process at the wafer plane, has become a standard. Now the company has introduced several new features for Prolith that enable users to optimize their mask designs and lithography processes for improved design for manufacturability (DFM). With the latest release of Prolith (version 9.0), customers can predict the manufacturability of extreme-resolution-enhancement techniques (xRETs) and other critical features using cost-effective, multi-algorithm simulations that take only minutes to complete, versus days or weeks for experiments. Prolith 9.0 also includes a new "mask-defect" option that enables users to determine the printability of mask defects and their impact on process windows.
"With the exponential increase in process complexity, and the pressures of cost and time-to-market that semiconductor manufacturers face today, all participants in the design-to-silicon chain have a vested interest in ensuring new designs are not only made manufacturable, but are also high-yielding," said Chris Mack, vice president of lithography technology at KLA-Tencor. "For twenty years, Prolith has played a key role in helping lithographers speed process development and improve their manufacturing processes. Today, that role has expanded to helping multiple industry stakeholders—from RET designers to mask shops, scanner equipment manufacturers, resist suppliers, and wafer fabs—optimize their processes to speed the manufacturability of new, high-yielding IC designs."
Extending optical lithography to smaller design nodes requires that today's photomasks incorporate a greater number of subresolution assist features, which increase lithography process complexity. Lithographers must determine how critical features will print across the entire lithography-process window in order to verify the manufacturability of the design before committing wafers to production. Prolith provides valuable information that can be used to optimize optical proximity correction (OPC), maximize critical dimension (CD)-limited yields, and minimize the disparity between the designer's intent and what is actually printed onto the wafer.
Prolith improves design manufacturability for all optical-lithography technologies and processes, including immersion, as well as all available mask technologies. New capabilities available in Prolith 9.0 include those that allow users to simultaneously move or resize each OPC and mask feature, or group of features, to enable significantly faster design and mask optimization. For example, the size and position of sub-resolution-assist features can be easily optimized in order to make a contact print correctly with the largest possible depth of focus. The new mask-defect option, described above, uses images from KLA-Tencor's TeraStar and TeraScan reticle-inspection systems. This option enables customers to develop more rigorous defect specifications for their advanced mask sets.