MASKED ION-BEAM LITHOGRAPHY FOR PROXIMITY PRINTING

Optical and X-Ray proximity printing systems are resolution limited by diffraction and beam dispersion. Parallel dispersion free ion beam sy stems are therefore ideal to transfer stencil mask patterns onto all s orts of nonideal substrates. A feasibility study was performed with th e existing Alpha ion projector of the Society for the Advancements of Microelectronics in Austria operated in the MIBL (Masked Ion Beam Lith ography) mode with approximate to 10x10 mm(2) exposure field. Structur es as small as 0.2 mu m in diameter could be transfered even with a ga p of 1 mm between stencil mask and substrate. The widening of resist l ines with 10% increase in dose was evaluated to be 14 nm for 2800 mu m gap and 4 nm for 300 mu m gap. This excellent exposure latitude favou rably compares with synchrotron based X-ray lithography, where a widen ing of 20 nm with 10% overexposure has been reported for a 40 mu m gap , and 10 nm for 10 mu m gap. Promising applications of the MIBL techni que include the fabrication of flat panel displays based on vacuum ele ctronics (field emitter displays), surface acoustic wave and microopti c devices and - in combination with reactive ion etching - the fabrica tion of micro electro mechanical systems (MEMS). Prospects for MIBL st eppers of printing fields > 100x100 mm(2) are discussed.