Method for measuring lens imaging uniformity

A method of measuring lens imaging uniformity across a substantial portion of a pattern transfer apparatus lens image field, comprising the steps of:

• generating a test reticle having a plurality of groups, wherein the groups include a plurality of reticle structures;
• measuring a dimension of two or more of the plurality of reticle structures of each group on the test reticle, thereby creating a first data set representing linewidth variations due to the test reticle generation at a plurality of points on the test reticle;
• transferring a pattern to a substrate using the test reticle, wherein the pattern includes a plurality of substrate pattern groups, wherein the wafer groups include a plurality of substrate structures corresponding to the plurality of reticle structures;
• measuring a dimension of two or more of the plurality of substrate structures, thereby creating a second data set representing substrate linewidth variations due to the test reticle generation and non-uniformities in an image optics system of the pattern transfer apparatus;
• and
• evaluating the first and second data sets, thereby identifying an amount of contribution to the substrate linewidth variations due to the test reticle generation, and thereby identifying the image optics system non-uniformity at a plurality of points in the lens image field.

A test reticle for measuring the lens imaging uniformity across a lens image field of a pattern transfer apparatus, comprising:

• a plurality of test structures formed on the test reticle, wherein at least one of the test structures has a different design linewidth different than the others of the plurality of test structures,
• wherein when the plurality of test structures are measured, linewidth measurements are collected for more than one design linewidth, thereby generating a first data set,
• wherein when patterns corresponding to the plurality of test structures are transferred to a substrate via the pattern transfer apparatus, a plurality of substrate structures are formed on the substrate and when the plurality of substrate structures are measured, linewidth measurements are collected for more than one patterned linewidth, thereby generating a second data set, and
• the first data set and the second data set are utilized to interpolate components of linewidth variations at a nominal linewidth.