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1988
Journal Article
Title
Sub-0.5-mym lithography with a new ion projection lithography machine using silicon open stencil masks
Abstract
An ion projection lithography system was equipped with an open stencil mask manufactured by applying silicon technology. By exposing poly(methylmethacrylate) and SiO2 to He+ions, the pattern, transferred with a 9.5:1 reduction, showed structures with a minimum linewidth of 0.25 mym. The emphasis of this work concentrated on the various effects which produce distortion of the mask. Whereas linear dilation of the foil caused by compressive stress and enhanced by the network structure could be offset by means of the ion optical system, anisotropic distortion which resulted from the unequally distributed openings in the pattern had to be minimized by applying a suitable design. With a field effect transistor test pattern, an average distortion of 0.15 mym has been obtained in a 20x21 sqmm area of the mask. Only minor contributions to pattern deviations were expected from the temperatur increase and sputter erosion. (IMT)