Tomohisa Fujisawa

Novel EUV resist development for sub-14nm half pitch

Extreme ultraviolet (EUV) lithography has emerged as a promising candidate for the manufacturing of semiconductor devices at the sub-14nm half pitch lines and spaces (LS) pattern for 7 nm node and beyond. The success of EUV lithography for the high volume manufacturing of semiconductor devices depends on the availability of suitable resist with high resolution and sensitivity. It is well-known that the key challenge for EUV resist is the simultaneous requirement of ultrahigh resolution (R), low line edge roughness (L) and high sensitivity (S). In this paper, we investigated and developed new chemically amplified resist (CAR) materials to achieve sub-14 nm hp resolution. We found that both resolution and sensitivity were improved simultaneously by controlling acid diffusion length and efficiency of acid generation using novel PAG and sensitizer. EUV lithography evaluation results obtained for new CAR on Micro Exposure Tool (MET) and NXE3300 system are described and the fundamentals are discussed.

Ultra-thin-film EUV resists beyond 20nm lithography

Extreme ultraviolet (EUV) lithography is one of the most promising technologies for achieving 22nm HP lithography and beyond. EUV resist is required to improve resolution limit down to less than 20nm hp. To achieve such a performance, innovative materials development is necessary under ultra-thin resist film condition for preventing line collapse. In addition, more refined etching processes compatible with ultra-thin resist film are needed. In this study, we will report our several approaches for both materials and processes towards forming less than 20nm HP pattern under ultra-thin film condition. We will also introduce our tri-layer system formed with combination of Si-ARC stack and organic hard mask (OHM) stack for refined etching process.

Simplified double patterning process with non-topcoat self-freezing resist

Double patterning is one of the most promising techniques for sub-30nm half pitch device manufacturing. Several techniques such as dual-trench process (litho-etch-litho-etch: LELE) and dual-line process (litho-litho-etch : LLE) have been reported. Between them, the dual-line process attracts a great deal of attention due to its higher throughput. The key issue in the dual-line process is preventing damage of the first resist pattern during the second lithography process. As a solution, we have developed a process to alleviate this issue using a chemical material called freezing agent. More recently, we have further simplified the process by developing a simple freezing technique called self-freezing or thermal-freezing. The self-freezing resist material can accomplish the freezing process by applying only one bake to the resulting first pattern. In addition, our self-freezing resist also has added water shedding properties to meet non-topcoat (non-TC) immersion resist requirements, which further simplifies the process and materials. In this study, imaging results of Non-TC self-freezing resist including critical dimension uniformity, defectivity and processing properties of the resulting patterns is shown.