Extreme ultraviolet (EUV) lithography, using 13.5 nm radiation, is considered one of the most prominent candidates for next generation lithography. The main challenge for EUV resists is to simultaneously satisfy resolution, LWR (line-width roughness) and sensitivity requirements according to the ITRS roadmap<sup>1</sup>. Over the past few years, our main effort has been to focus on ZrO<sub>2</sub> and HfO<sub>2</sub> nanoparticle-based photoresists. However, both Zr and Hf are relatively low EUV absorbing metals<sup>2</sup>, and integration of high EUV absorption elements is considered to be a more promising route to further improve lithographic performance under EUV radiation. Here, we demonstrate novel zinc oxide-based nanoparticle photoresists, possessing small particle size, good solubility in spin-coating solvents, good film-forming abilitie and patterning by incorporating a photo-acid generator or photo-radical generator.
With the rapid development of semiconductors, today's optical lithography is approaching its physical limits, and thus alternative patterning technology is urgently desired. Extreme ultra-violet (EUV) lithography, using a wavelength of 13.5 nm, is considered one of the most prominent candidates for next generation lithography. The main challenge for EUV resists is to simultaneously satisfy resolution, LWR (line-width roughness) and sensitivity requirements following the ITRS roadmap. Though polymer-based CAR (chemically amplified resist) is the current standard photoresist, entirely new resist platforms are required due to the performance targets of smaller process nodes. In this paper, our recent progress in metal oxide nanoparticle photoresist research will be discussed. Brief discussion of a number of important structure and property issues pertaining to key characteristics affecting resist performance is also included.
EUV lithography is nowadays considered as one of the most feasible choices for high volume manufacturing. In this work, we wish to report a series of studies aiming at shedding more light on the development mechanism of metal based EUV hybrid photoresists. We have studied zirconium (Zr) and hafnium (Hf) based hybrid resists which have shown high sensitivity, they suffer though from scumming issues. On the other hand, our clusters based on zinc (Zn) which absorbs strongly in EUV seem to be free of scumming but still Zr and Hf outperform in terms of sensitivity. In an effort to understand better what controls sensitivity and scumming phenomena we have employed a combination of analytical techniques (Electrospray ionization mass spectrometry ESI-MS, X-ray photoelectron spectroscopy XPS, and Fouriertransform infrared spectroscopy FT-IR) to study the patterning mechanism in detail, in order to be able to optimize the development process and develop systems with optimal features.
In order to understand the mechanism of the pattern wiggling distortion and to find control knobs for improving wiggle performance of spin-on carbon hard mask materials, we have developed analysis method of underlayer (UL) films by utilizing XPS depth profiling using Gas Cluster Ion Beam(GCIB-XPS). Differences of distributions of elemental compositions from the surface to the bottom of the processed or un-processed films have been visualized by GCIB-XPS analysis. Besides, these achievements allow us to identify fluoro substitution of oxygen during etching process as the control knob for the pattern wiggling distortion.