Study of Test Structures for Use as Reference Materials for Optical Critical Dimension Applications

Optical critical dimension (OCD) metrology has rapidly become an important technology in supporting the worldwide semiconductor industry. OCD relies on a combination of measurement and modeling to extract the average dimensions of an array of parallel features, having fixed pitch and drawn linwidth. This paper reports results of OCD measurements on arrays selected to serve as prototype reference structures. In addition, SEM CD measurements were made on several of these structures to verify line uniformity. These prototypes are fabricated using the single-crystal CD reference materials (SCCDRM) process, which in prior work has been successfully applied to isolated feature reference materials. The SCCDRM process provides features with known geometries, typically vertical sidewalls, defined by the silicon lattice.