Dose modulation and pixel deflection for raster scan lithography

A raster scan photolithography apparatus comprising:

• a beam generator;
• a support for a medium sensitive to exposure from the beam;
• a raster scanning system located between the beam generator and the support for scanning the beam across the medium in a raster pattern having a plurality of pixels to expose a feature on the surface of the medium defined by some of the pixels;
• a beam blanker located between the beam generator and the support for blanking the beam, thereby defining the pixels;
• and
• a beam blanker controller operatively connected to the beam blanker for reducing a duration of the pixels located at an edge of the feature to at least two predetermined levels each intermediate of a zero duration and a full pixel duration.

A raster scan photolithography apparatus adapted for defining an edge of an exposed feature at a location lying off a grid defined by the raster, comprising:

• a beam generator;
• a lens for deflecting the beam;
• a support for a medium sensitive to exposure from the beam;
• a raster scanning system for scanning the beam across the medium in a raster grid pattern having a plurality of pixels;
• and
• a deflection controller for deflecting a location of at least some of the pixels to at least two predetermined locations intermediate of locations defined by the raster grid pattern.

A method of exposing a medium which is sensitive to exposure from a beam in a raster scan lithography apparatus, so as to achieve a feature edge location finer than a grid defined by the raster, comprising the steps of:

• scanning the beam across a surface of the medium in a raster pattern, thereby exposing a plurality of pixels of the raster pattern on the medium to form at least one exposed feature on the surface of the medium, the feature including the plurality of the pixels and having at least one edge;
• reducing a duration of the exposure of at least some of the pixels at the edge of the feature, thereby defining the edge of the feature as a line lying off a grid defined by locations of the pixels of the raster pattern;
• and
• deflecting the beam while it is scanning at least some of the pixels at the edge of the feature, thereby locating the pixels at the edge at locations lying off the grid.