Photomask immersion draws overflow meeting attendance

Attendance at the annual SPIE Photomask Technology meeting this year (Oct. 3-7) climbed to 1155, up from 967 last year, with a 66% increase in short course attendance.

MONTEREY, CA - Attendance at the annual SPIE Photomask Technology meeting this year (Oct. 3-7) climbed to 1155, up from 967 last year, with a 66% increase in short course attendance. An area of primary interest both in technical presentations and on the exhibit floor was the progress of 193-nm immersion lithography toward volume manufacturing and smaller feature sizes.

Addressing both the opportunities and challenges presented by immersion is requiring an increased reliance on computer simulation and modeling capabilities to cost-effectively validate designs, perform optical proximity corrections (OPC), and add the reticle enhancement technologies in the mask-making process that enable high yield in manufacturing. Two providers of electronic design automation (EDA) software announced collaborative agreements at the meeting focused on such concerns.

Synopsys (Mountain View, CA) is working with SEMATECH (Austin, TX) to develop advanced OPC models in support of SEMATECH’s 193-nm Immersion Lithography Extendibility Project, focused in large part on reduction of feature sizes through the 45-nm node. The objective of the collaboration is to eventually enable the extension of immersion lithography to the 32-nm half-pitch, and to develop models for optical tools with a numerical aperture of 1.55 and greater.

Several aspects of the collaboration are “unprecedented,” according to Srinivas Raghvendra, senior director of business development and marketing for DFM (design-for-manufacturing) solutions at Synopsys. One is beginning such work so far ahead on the roadmap-all the way down to 32 nm, when even factors such as resist details for 45 and 32 nm are not yet in place, which makes it overall a very experimental and research process. The potentially high NAs make immersion difficult to model, Raghvendra said. Modeling factors such as polarization effects for OPC and 3D mask effects will actually break new ground. An additional metrology challenge will also be posed by the 1.5-nm accuracy budget required at the 45-nm node.

Shane Palmer, assigned from Texas Instruments (Dallas, TX) as senior technologist for the SEMATECH project, says the project has shown good progress through the initial months, producing the first set of models and expecting to publish initial papers perhaps by next year.

“The bad news is that there are yield problems,” Raghvendra said. “The good news is that they are all amenable to design measures.”

Brion Technologies (Santa Clara, CA), another provider of EDA software, announced a joint development agreement at BACUS with STMicroelectronics (Geneva, Switzerland), Philips Semiconductors (Eindhoven, The Netherlands) and Freescale Semiconductor (Austin, TX), R&D partners in the Crolles2 Alliance. Unlike the Synopsis-SEMATECH collaboration focusing on the future at 45-nm, Brion is working with Crolles2 on manufacturing and yield issues at 90 and 65 nm nodes. Brion has delivered RET/OPC process window-enabled applications and intends to further test and develop these applications with the Crolles2 Alliance partners. Comprehensive model-based simulations of multiple focus and exposure conditions are used to enable larger process windows for advanced manufacturing by avoiding yield-limiting lithography “hot spots,” according to Jim Wiley, senior technical director at Brion.

Wiley said that the collaboration between Brion and Crolles2 actually began last spring. Brion, a three-year-old startup company, officially launched its EDA software product last February at the SPIE Microlithography meeting. Wiley said the company had 10 paying customers and 22 machines in the field. Brion expects to achieve market-leading revenues by the end of this year. He said a primary factor in the company’s growth has been their reputation for very rapid simulations without sacrificing accuracy in an industry where time is always of the essence.

- Hassaun A. Jones-Bey

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