NOVELTY - The method (200) involves implanting (206) dopant impurity atoms of second, opposite, conductivity type in portions of non-implanted regions of silicon layer to form second implanted regions and resulting in remaining non-implanted regions of silicon layer, through second shadow mask. The remaining non-implanted regions of the silicon layer with a selective etch process, is removed (208), to preserve the first and the second implanted regions of the silicon layer. The first and second implanted regions of layer are annealed (210) to form doped polycrystalline silicon emitter regions.    USE - Method for fabricating alternating N-type and P-type emitter regions of solar cell (claimed) using ion implantation, and solar cells.    ADVANTAGE - The effective, process operation saves generating separate N- and P-doped polycrystalline silicon finger emitters covering the backside of a high efficiency solar cell using patterned ion implant technology. The introduction of new high throughput ion implant tools targeting high efficiency solar applications with patterning capabilities is applicable to the fabrication of interdigitated back contact (IBC) solar cells. Since using a narrower dimension for the slit in the second mask allows for misalignment tolerance without risk of having ancillary impurity species implanted outside of the N+ region.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for a back contact solar cell.    DESCRIPTION OF DRAWING(S) - The drawing shows a flowchart illustrating the process for fabricating the solar cell.    Method for fabricating the solar cell (200)    Step for forming silicon layer above a substrate (202)    Step for implanting dopant impurity atoms of second, opposite, conductivity type in portions of the non-implanted regions of the silicon layer (206)    Step for removing the remaining non-implanted regions of the silicon layer with a selective etch process (208)    Step for annealing the first implanted regions and the second implanted regions of the silicon layer to form doped polycrystalline silicon emitter region (210)