Recent progress of LEEPL mask technology

LEEPL mask specifications for LEEPL volume production tool "EBPrinter LEEPL-3000" have been fixed and 1X LEEPL stencil masks for 65 rim node device fabrication have been developed and evaluated. "EBPrinter LEEPL-3000" handles a 6025 type mask which is compatible with a 6025 photo mask and a 200 mm wafer type mask. Both of masks have silicon based membranes with a thickness of 0.5 um - 2.0 um. Exposure field size of "EBPrinter LEEPL-3000" is 46 mm X 46 mm, and pattern area of the LEEPL mask is the same 46 mm X 46mm which covers four fields of an optical stepper and a field of an optical scanner. Obtaining small patterns, high CD accuracy and high image placement (IP) accuracy are very important for a 1 X mask. Less than 70 nm patterns with a CD accuracy of 6.9 nm were obtained. As "EBPrinter LEEPL-3000" has a mask global IP error correction function using a sub-deflector, specification of IP error is not so critical. Specification of global IP error is less than 30 run, and local IP error is less than 10 rim. Those are easily obtained with membrane stress control and a multiple exposure method of electron beam mask exposure systems.