An improved, lower cost method of processing substrates, such as to create solar cells, is disclosed. The doped regions are created on the substrate, using a mask or without the use of lithography or masks. After the implantation is complete, visual recognition is used to determine the exact region that was implanted. This information can then be used by subsequent process steps to crate a suitable metallization layer and provide alignment information. These techniques can also be used in other ion implanter applications. In another aspect, a dot pattern selective emitter is created and imaging is used to determine the appropriate metallization layer.