Sematech and Zeiss Report Progress on Mask Metrology Tool
Staff -- Semiconductor International, 2/25/2008 8:14:00 AM
A team of more than 40 engineers at Carl Zeiss SMT (Jena, Germany), working with the lithography program of Sematech (Albany, N.Y.), today announced design completion of the next generation Photomask Registration and Overlay Metrology system (PROVE) for mask pattern alignment and registration.
The tool is targeted for production by the end of next year, with mask manufacturers as the primary customers.
Oliver Kienzle, a manager of the Zeiss metrology systems division, said the system “will close the technology gap for overlay metrology at 32 nm and beyond,” including masks used in double patterning, which require tighter image placement control on the masks, and future extreme ultraviolet (EUV) exposure systems.
Earlier, Carl Zeiss SMT and Sematech worked on a metrology tools for immersion lithography, resulting in the AIMS tool. In April 2007 an evaluation team of mask makers and Sematech member companies reviewed proposals from several suppliers for a tool capable of 32 nm generation requirements. Carl Zeiss was chosen to develop the system, and since then Zeiss SMT and Sematech engineers have partnered to develop the concept into a working metrology tool.
The PROVE system employs diffraction-limited, high-resolution imaging optics, operating at 193 nm, which provides at-wavelength metrology for masks used in 193 nm scanners. The system also features through-pellicle measurements. It operates in both transmission mode and reflection mode for EUV measurements. The photomask resides on a precision stage which is the only movable part in the imaging path.
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| Michael Lercel, Director of Lithography, Sematech |
Patricia Gabella, Sematech project engineer and manager of the joint project, said, “With double patterning coming on strong as an optical extension, registration tolerances are getting even smaller. Working with Carl Zeiss SMT we have completed a design for quantifying image placement errors as small as 2.4 nm according to the ITRS roadmap. This is a major milestone towards making double patterning a commercially viable technology.”
