LineDiff Entropy: Lossless Layout Data Compression Scheme for Maskless Lithography Systems

This letter presents a new lossless electron-beam layout data compression and decompression algorithm named LineDiff Entropy. The algorithm is designed to facilitate high volume data transfer and massively-parallel decompression in electron-beam direct-write lithography systems. LineDiff Entropy first compares consecutive electron-beam data scanlines and encodes the data based on change/no-change of pixel values and length of corresponding sequences. Then LineDiff Entropy utilizes the entropy encoding technique to assign unique short codes to data of frequent occurrence. Because the code format is simple and effective, LineDiff Entropy decompression can be achieved with limited computing resources. The benchmark results show that LineDiff Entropy is capable of achieving excellent compression factors and very fast decompression speed.