Yield modeling and enhancement for optical lithography

A method is presented for predicting the CD limited yield of a photolithographic process using well established lithography modeling tools. the lithography simulator PROLITH/2 is used to generate several multivariable process response spaces (for example, final resist critical dimension (CD) versus focus, exposure, resist thickness, etc.). Error distributions are determined for each input variable. By correlating the input error distribution with the process response space, a final CD distribution is generated. Analysis of the output distribution produces a predicted parametric CD yield. By analyzing predicted CD yield for multiple geometries, a yield curve (yield vs. feature size) is determined for an i-line process. By comparing CD yield for different nominal exposure doses, a yield-exposure curve is calculated for an i-line process.