An apparatus for wafer edge exposure comprises a first exposure unit and a second exposure unit. The first exposure unit includes a first light source to emit first light of multiple wavelengths, and a first mask to direct the first light toward a first area at an edge portion of a wafer. The second exposure unit includes a second light source to emit second light of a single wavelength, and a second mask to direct the second light toward a second area at the edge portion of the wafer. The second area encloses a transition area that borders the first area under the first mask.