Distributed, multiple variable shaped electron beam column for high throughput maskless lithography

The ultimate resolution obtainable with focused electron beams is, for prac tical purposes in lithography, unlimited. Existing e-beam lithography syste ms are too slow to be practical for high volume manufacturing of semiconduc tor devices, however. The usable current in probe forming systems is limite d by the stochastic Coulomb interaction in the beam path, which causes loss of resolution at high current. This is due to the need to pass all of the writing current through an aperture. Distributed systems, by contrast, do n ot suffer from this problem, as the current is spread over a large volume. The purpose of this article is to propose a distributed system, employing m ultiple, variable shaped beams for direct write (maskless) lithography. We call this system DiVa, to emphasize the key attributes of distributed writi ng current, and variable beam shaping. It utilizes a planar cathode, patter ned with a rectilinear array of square emitters. Focusing is accomplished b y a uniform, axial magnetic held, oriented along the optic axis. This trans fers a one-to-one image of the emitters onto the writing surface. Deflectio n plates between adjacent rows of beamlets effect motion in one Cartesian a xis, while mechanical translation of the stage effects motion in the orthog onal axis. Theoretical resolution is diffraction limited to 4.6 nm at 50 kV . Experimental results are presented which demonstrate the first order opti cs using a rudimentary apparatus. (C) 1998 American Vacuum Society. [S0734- 211X(98)14406-2].