REAP (Raster E-Beam Advanced Process) Using 50kV Raster E-beam System for Sub-100nm Node Mask Technology

摘要

A chemically amplified resist (CAR) process has been recognized as an approach to meet the demanding critical dimension (CD) specifications of 100nm node technology and beyond. Recently, significant effort has been devoted to optimizing CAR materials, which offer the characteristics required for next generation photomask fabrication. In this paper, a process established with a positive-tone CAR from TOK and 50kV MEBES~(~R) eXara~(TM) system is discussed. This resist is developed for raster scan 50 kV e-beam systems. It has high contrast, good coating characteristics, good dry etch selectivity, and high environmental stability. The coating process is conducted hi an environment with amine concentration less than 2 ppb. A nitrogen environment is provided during plate transfer steps. Resolution using a 60nm writing grid is 90nm line and space patterns. CD linearity is maintained down to 240nm for isolated lines or spaces by applying embedded proximity effect correction (emPEC). Optimizations of post-apply bake (PAB) and post-expose bake (PEB) time, temperature, and uniformity are completed to improve adhesion, coating uniformity, and resolution. A puddle develop process is optimized to improve line edge roughness, edge slope, and resolution. Dry etch process is optimized on a Tetra~(TM) system to transfer the resist image into the chrome layer with minimum etch bias. Details of this process and data on resolution, lithography integrity, CD linearity, and CD uniformity will be presented. In conclusion, a CAR process is demonstrated with the new 50kV MEBES system, which meets the requirements of sub-100nm node technology.