Lossless Compression Algorithm for REBL Direct-Write E-Beam Lithography System
Avideh Zakhor, Hsin-I Liu and George Cramer
Semiconductor Research Corporation and Defense Advanced Research Projects Agency
Future lithography systems must produce more dense microchips with smaller feature sizes, while maintaining throughput comparable to today’s optical lithography systems. This places stringent data-handling requirements on the design of any maskless lithography system. Today’s optical lithography systems transfer one layer of data from the mask to the entire wafer in about sixty seconds. To achieve a similar throughput for a direct-write maskless lithography system with a pixel size of 22 nm, data rates of about 12 Tb/s are required. Our proposed system achieves this data rate contingent on two assumptions: consistent 10 to 1 compression of lithography data, and implementation of real-time hardware decoder, fabricated on a microchip together with a massively parallel array of lithography writers, capable of decoding 12 Tb/s of data.
We present a modified version of Block GC3 , a lossless compression algorithm, which has been customized to optimize compression efficiency for use with the REBL Direct-Write E-Beam Lithography System by KLA-Tencor. Layout images are now assumed to be rotated by any arbitrary angle, and have been generated using E-Beam proximity correction (EPC) techniques. Our results show that compression efficiency of 7.2 is attainable, which outperforms all existing lossless compression algorithms. In addition, Block GC3 has been shown to be feasible for hardware implementation, which makes it promising for integration with the REBL system.
- H. Liu, V. Dai, A. Zakhor, B. Nikolic, "Reduced Complexity Compression Algorithms for Direct-Write Maskless Lithography Systems," SPIE Journal of Microlithography, MEMS, and MOEMS (JM3), Vol. 6, 013007, Feb. 2, 2007.