Wh. Brunger et al., EDGE ROUGHNESS OF A 200-NM PITCH RESIST PATTERN FABRICATED BY ION PROJECTION LITHOGRAPHY, Journal of vacuum science & technology. B, Microelectronics and nanometer structures processing, measurement and phenomena, 11(6), 1993, pp. 2404-2408
The edge roughness of test patterns fabricated by ion projection litho
graphy has been investigated to indicate the optimum experimental cond
itions for sub-100-nm resolution. Direct observation in a scanning ele
ctron microscope, electron metrology, and atomic force microscopy has
been employed for the evaluation of widths in the resist structures. I
mperfections in the open stencil mask give rise to the main part of ed
ge roughness, especially if electrostatic charging occurs. Lines and s
paces in PMMA resist developed with high contrast show a roughness of
10 nm per edge if the mask has no defects and the projection system an
d resist performance have been adjusted satisfactorily. Statistical fl
uctuations of the ion current have no influence if a medium sensitive
resist like PMMA is used resulting in exposure times of 100 ms.