Defect mitigation and characterization in silicon hardmask materials

The silicon hardmask (Si-HM) is one of the key materials used in multilayer lithography for pattern transfer to a substrate using a fluorinated plasma etching process. Manufacturing of devices with smaller feature sizes introduces new challenges in defect control of all the critical layers, including the Si-HM layer used in photolithography. One of the major challenges of Si-HM materials includes intrinsic defect formations, which can be exacerbated by the presence of foreign contaminants such as soft and hard particles, organics, and metal-ionic contaminants. These contaminants are also known to induce defects by interfering with the plasma etch processes used in advanced patterning technologies. The contaminants can range from microns to angstroms in size. The identification and characterization of the defect adders is important to develop filtration methods capable of minimizing the number of on-wafer defects and consequently improving the quality. In this study, metal contaminants, liquid particle count and on-wafer defects of Si- HMs and filtration removal rates are monitored to determine the effect of filter type, pore size, media morphology, and cleanliness on filtration performance. 5-nm PTFE NTD2 filter having proprietary surface treatment used in this study shows lowest defect count.