ORA Wins $1.7 Million for advanced lithography modeling
Pasadena, CA, May 14, 2004--The National Institute of Standards and Technology (NIST; Boulder, CO) has awarded Optical Research Associates (ORA) a $1.7 million Advanced Technology Program (ATP) award for the development of advanced-lithography-modeling algorithms. The ATP, which selects recipients through an annual award cycle, provides cost-shared funding to industry for high-risk research and development projects that have the potential to spark important, broad-based economic benefits for the United States.
The award will fund ORA's "Fundamental Algorithms for Direct Metric Tolerancing and Illumination Optimization" project, which will focus on overcoming technical and modeling limitations in the current generation of software used by industry to design and build optical systems for semiconductor devices.
Projection lenses for photolithographic equipment (and their associated illuminators) are some of the most precise and sophisticated optical systems ever conceived and fabricated. For example, a projection lens that accurately images 0.1-micron features over a 20 x 20-mm field must not only image 2 x 1010 points, but also must do it with a vanishingly small amount of distortion. As lithographic feature sizes become smaller and field sizes are driven to be as large as possible, the lenses (refractive or refractive/reflective for 193-nm and 157-nm wavelengths, and all-reflective for the 13-nm extreme-ultraviolet wavelength) become ever-harder to model.
Over the years, optical-design software used for these lenses has become just as sophisticated; such software must also take into account the effects of manufacturing tolerances at a very deep level. But optimizing lenses based on, for example, minimizing wavefront error is not enough; perfecting actual photoresist images is the key.
ORA's research will focus on the development of algorithms to help the industry meet improve both technologies under development now (193-nm and 157-nm lithography) and the next-generation extreme-ultraviolet (EUV) systems.
ORA's approach is two-pronged. First, ORA will develop direct-metric tolerancing and compensator selection for projection optics. If successful, this will allow accurate calculation of optical-system performance based directly on key performance metrics during the crucial process of developing the fabrication and assembly tolerances and methods, rather than on derivatives of these metrics (such as RMS wavefront error). Accurate calculations of optical errors will help designers maximize the performance of their equipment, effectively boosting manufacturing and product yields and extending the lifetime of a particular technology node.
Just as important, ORA will develop algorithms for optimization of illumination systems in EUV lithography (proper illumination--filling the lens entrance pupil properly--is crucial to achieving sharply defined image features). These new illumination-optimization algorithms will help designers collect and shape the output of EUV sources to achieve higher throughput and more uniform illumination at the surface of the wafer. ORA's goal for the EUV illumination optimization algorithms is to improve product throughput or yield at the chip level by 10% to 25%.