Patent ID: 7027156

Claim:
A method of aligning a template with a portion of a substrate, comprising: placing a patterned template at a spaced relation to a substrate, wherein the patterned template comprises a template alignment mark, and wherein the substrate comprises a substrate alignment mark, and wherein the template alignment mark and the substrate alignment mark are grating structures; illuminating the template alignment mark and the substrate alignment mark with light at an angle that is substantially normal to a plane defined by the substrate; measuring light at a first wavelength reflected from the template alignment mark and the substrate alignment mark at a non-zero order with a light detector; determining a first alignment error of the template alignment mark with respect to the substrate alignment mark based on light measurements collected at the first wavelength of light; measuring light at a second wavelength reflected from the template alignment mark and the substrate alignment mark at a non-zero order with the light detector; determining a second alignment error of the template alignment mark with respect to the substrate alignment mark based on light measurements collected at the second wavelength of light with the light detector; determining an average alignment error, wherein the average alignment error is a function of the first and second alignment errors; and altering the position of the patterned template with respect to the substrate to compensate for the alignment error.