NOVELTY - The method comprises: implanting (1000) ions through a mask into a substrate to create an implanted feature; performing (1300) thermal annealing the substrate; determining (1100) a location of the implanted feature; placing (1200) a fiducial onto the substrate at a known position with respect to the implanted feature; detecting a position of the fiducial; aligning the fiducial with the implanted feature using the position of the fiducial; and adjusting a position of the mask to align with the fiducial using one of a charge-coupled-device (CCD) camera, an infrared camera, and a photodiode.    USE - The method is useful for processing a substrate to produce a solar cell (claimed).    ADVANTAGE - The method is capable of economically and rapidly producing the solar cell in a reliable manner with reduced complexity, and maintaining adequate accuracy so that masks are correctly positioned during subsequent process steps.    DETAILED DESCRIPTION - The method comprises: implanting (1000) ions through a mask into a substrate to create an implanted feature; performing (1300) thermal annealing the substrate; determining (1100) a location of the implanted feature; placing (1200) a fiducial onto the substrate at a known position with respect to the implanted feature; detecting a position of the fiducial; aligning the fiducial with the implanted feature using the position of the fiducial; adjusting a position of the mask to align with the fiducial using one of a charge-coupled-device (CCD) camera, an infrared camera, a photodiode and a laser; and registering the fiducial to one of first and second adjacent edges or a corner of the substrate before the step of implanting the ions into the substrate. The step of determining the location of the implanted feature comprises detecting the fiducial with one of the CCD camera, the infrared camera, the photodiode and the laser. The fiducial is placed on the substrate before or subsequent to the step of implanting the ions into the substrate. The implanted feature is optically visible before to the step of thermal annealing, and is not optically visible subsequent to the step of thermal annealing. The fiducial is optically visible subsequent to the step of thermal annealing. The fiducial on the substrate is optically visible subsequent to the step of thermal annealing. The method further comprises: applying the fiducial to the substrate before the step of thermal annealing the substrate; and determining a distance from the fiducial to the first and second adjacent edges of the substrate. The position of the mask is adjusted to align with a fiducial to align the mask with the implanted feature. An INDEPENDENT CLAIM is included for an apparatus for implanting workpieces.    DESCRIPTION OF DRAWING(S) - The diagram shows a flow chart of a method for processing a substrate to produce a solar cell.    Implanting ions through a mask into a substrate to create an implanted feature (1000)    Determining a location of the implanted feature (1100)    Placing a fiducial onto the substrate at a known position with respect to the implanted feature (1200)    Performing thermal annealing the substrate (1300)    Aligning a pattern mask with respect to the fiducial. (1400)