KLA Drops Back to PASS

Electronic News, July 2, 2001 by Jeff Chappell

Numeritech releases attenuated PSM inspection software

KLA-Tencor Corp. and Numerical Technologies Inc.'s OEM agreement continues as KLA-Tencor released reticle inspection software today based on Numeritech's Virtual Stepper.

The Printability Analysis Stepper Simulator (PASS) software uses an attenuated phase-shifting mask (PSM) module available for Numeritech's (nasdaq: NMTC) Virtual Stepper software package that it publicly unveiled today.

Virtual Stepper analyzes inspection data of subwavelength photomasks incorporating optical proximity correction (OPC) and phase-shifting aspects and determines how mask defects will print on a wafer. PASS can characterize defects without having to move a photomask from an inspection tool to an off-line aerial defect imaging tool, according to San Jose-based KLA-Tencor (nasdaq: KLAC).

"PASS takes the guesswork out of determining if a subwavelength photomask will work as it was intended," Lance Glasser, vice president and general manager of KLA-Tencor's Mask Inspection division, said in a statement. "As a result, our mask manufacturer customers avoid having to rely on operator expertise to make these determinations as well as avoid the expense of making unnecessary repairs or scrapping the photomask altogether."

PASS automatically simulates how the defects will print onto the wafer before the photomask is shipped to a customer or used in production. It takes defect data and images collected by the reticle inspection tool and simulates the image of the circuit pattern and defects projected onto the wafer. PASS then compares the variation between the simulated data and the actual defect data to determine how the defects might print onto a wafer.

PASS, which analyzes binary hard (chrome) defects, OPC features and assist line geometries, is available for all of KLA-Tencor's current reticle inspection tools, including the 3XX, SL3, SL3UV and Tera series tools introduced last fall.

KLA-Tencor officials couldn't be reached for comment prior to press tune, but Numeritech said it is excited about the dual announcement of the attenuated PSM module and its integration with KLA-Tencor's tools.

"This is where the future is," said Atul Sharan, senior vice president of marketing and business development. "This is where the problems are (and) where the opportunities are." Inspecting masks and fixing every error with no consideration as to whether they would create critical defects on silicon--the way it is typically done with binary masks--is no longer feasible as more subwavelength IC designs come into existence, Sharan said.

This only serves to drive up mask costs that are already skyrocketing as masks incorporate OPC and PSM to overcome the physics of deep-ultraviolet light and print sub-0.18-micron lines.

While Numeritech works with other tool OEMs, the company has a preferred provider agreement with KLA-Tencor. The metrology toolmaker has already been bundling Virtual Stepper with its tools on a limited basis.