Apparatus and method for printing a periodic pattern with a large depth of focus

摘要

An apparatus and a method for printing a desired pattern into a photosensitive layer. A mask bears a pattern of linear mask features parallel to a first direction. The layer is arranged parallel to and separated from the mask. Substantially monochromatic light is generated and the mask pattern is illuminated with the light over a range of angles of incidence in a plane parallel to the first direction, at substantially a single angle in an orthogonal plane of incidence and so that the light of each angle of incidence transmitted by the mask forms a light-field component at the layer. The integration of the components prints the desired pattern. The range of angles is selected so that the integration of the components is substantially equivalent to an average of the range of transversal intensity distributions formed between Talbot image planes by light at one of the angles of incidence.

主权项

1. An apparatus for printing a desired periodic pattern of linear features into a photosensitive layer formed on a substrate, the apparatus comprising:
a) a mask bearing a mask pattern of linear mask features that are parallel to a first direction; said linear mask features having a period that is twice that of the desired pattern; b) a means for arranging the photosensitive layer parallel to the mask and with a separation from the mask pattern; c) a means for generating monochromatic light at a wavelength; and d) a means that illuminates the mask pattern with said light with a range of angles that lies substantially in a plane parallel to said first direction, so that the light at each angle of illumination transmitted by the mask forms Talbot image planes and exposes the photosensitive layer to an angle-dependent transversal intensity distribution, whereby an integration of said distribution over the range of angles prints the desired periodic pattern; wherein the range of angles, the wavelength, the separation and the period are such that changing the angle of illumination across the range would cause a particular transversal intensity distribution initially exposing the photosensitive layer to displace longitudinally with respect to the layer by at least the distance between successive Talbot image planes formed by light at the mean angle of said range of angles.