MRI: Development of an Energetic Atom Beam Lithography System for Nanosystem Prototyping and Manufacturing

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The remarkable increase in the processing power of silicon integrated circuits over the last half-century was enabled by a scalable lithographic approach that advanced through the generations by reducing the wavelength of the exposing radiation; first visible light (435 nm), then ultra-violet (365 nm), and now the deep-ultraviolet wavelengths (193 nm) that will drive the minimum feature size in manufacturing to 45 nm within 5 years. To advance further requires even smaller wavelengths, possibly soft x-rays (13 nm) or charged particles, electrons or light ions (10-6 nm). However, the sub-nanometer pattern placement accuracy and line edge roughness needed at this scale is significantly more challenging with charged particles than with photons owing to their electrostatic interaction with fixed, or mobile, charge in the mask or on the wafer. Our approach uses energetic neutral hydrogen atoms to provide immunity to charge build-up while, at the same time, limiting diffraction to that of protons. We propose to develop a turn-key, mass-selected, atom beam lithography instrument with 5-10 nm resolution over a 2 cm2 exposure field and sub-10 second exposure times. An instrument with these specifications will dramatically improve nanosystem prototyping capability both at the University of Houston and Nationally. It will also provide a test-bed for nanosystem manufacturability. The development project involves the following key tasks: (1) The development and characterization of a high brightness, energetic hydrogen atom source using a mass-selected, multicusp proton source and a high pressure gas cell to convert the parent proton beam to neutral hydrogen atoms. (2) The development and characterization of a novel pulsed source concept with ultra-low energy spread. This will significantly enhance the throughput of the basic system developed in task 1, above. (3) The development of an ultra-high precision nanostepping system with a lead-screw driven, interferometrically-controlled, wafer stage and a piezoelectric, flexure stage for the mask. We will explore the fundamental resolution limit of atom beam lithography due to the combined effects of diffraction, penumbra, shot noise, secondary electron range, and resist scattering during the qualification tests of the instrument.