Advanced pattern correction method for fabricating highly accurate reticles

摘要

We have investigated a new pattern correction method for reducing pattern critical dimension (CD) errors due to a variety of pattern layouts and densities. Together with conventional proximity effect correction and fogging functions in an electron beam (EB) writing process, the new pattern correction was introduced for correcting CD errors that occur during a dry etching process. A rule-based OPC software was used to modify EB pattern shapes. In addition to the spaces between neighboring patterns, the surrounding pattern density was chosen as a correction parameter. First, we optimized the pattern correction table by measuring the CDs of various symmetric 3 lines with 5 levels of surrounding pattern densities. Next, we applied the pattern correction to semi real device patterns. From the measurement for 100 patterns of them, CD uniformity of 15.0 nm (3-sigma) was obtained. We confirmed the effectiveness of the pattern correction method.