Abstract: The apparatus includes a particle beam, having an axis which functions as a primary optical axis, which particle beam is used to generate a pattern on a substrate. The apparatus also includes an optical reader, having an axis which functions as a secondary optical axis. A position fiducial is located at a stationary position relative to the substrate. Registration of a pre-existing pattern and the particle beam axis to the position fiducial periodically during production of a particle-beam-generated pattern continually provides an improvement in the overall alignment of the pattern being created with the pre-existing pattern on the substrate.

Abstract: A significant improvement in the alignment of a particle-beam-generated pattern relative to a pre-existing pattern present on a substrate has been accomplished using optical measurement to register the particle beam to the pre-existing pattern. Use of a position fiducial which can be accurately measured by both an optical microscope and a particle beam axis is used to align a pre-existing pattern with a particle-beam-generated pattern during writing of the particle-beam-generated pattern. Registration of the pre-existing pattern to the fiducial and registration of the particle beam axis to the fiducial periodically during production of the particle-beam-generated pattern continually provides an improvement in the overall alignment of the pattern being created to the pre-existing pattern on the substrate. The improved method of alignment can be used to correct for drift, or thermal expansion, or gravitational sag, by way of example.