Inorganic-infiltrated polymer hybrid thin film resists for advanced lithography

Background

Lithography-based patterning has been instrumental in achieving the tremendous computational power and high device density possessed by today's modern computer chips. Extreme ultraviolet (EUV) lithography, with a short wavelength of 13.5 nm, is being implemented for high volume manufacturing, which is expected to decrease the number of patterning steps in the fabrication process flow as well as decrease the layout complexity by replacing multi‑patterning steps with single‑step EUV patterning. However, the resists for EUV lithography pose rigorous requirements such as high optical absorption, high etch resistance, high sensitivity and resolution as well as low line edge roughness. Traditional carbon‑based resist materials fall short in meeting these necessities, so metal containing organic‑inorganic hybrid resists are being investigated. These metal‑containing materials offer an increase in etch resistance due to the addition of more robust metal atoms into the polymeric backbone and improvement in line‑edge roughness due to the use of smaller molecules. Also, the addition of metals with a high EUV absorption coefficient could be utilized for enhancing resist sensitivity. Many avenues are being investigated for developing EUV resist materials containing metal atoms such as metal oxide nanoparticles, metal containing oxo‑cages, and metal‑containing salt complexes. However, all of these approaches either require establishment of new infrastructure or suffer from limited shelf‑life.

Technology

Researchers at Stony Brook University (SBU) propose a new invention that provides improved methods to prepare resist materials for advanced lithography using existing infrastructure and materials without the need for complex chemical synthesis methodologies. This method relies upon infiltrating certain metals such as Al, Zn, Sn, Ti, Zr, Hf, In, Sb, Co, Ni, Pd, W, Pt, Au, as well as their oxides into the thin films of resist materials such as poly(methyl methacrylate) (PMMA) and similar acrylate based resist derivatives, ZEP series, CSAR series, polysterene derivatives, and poly(2-vinylpyridine) derivatives to synthesize hybrid nanocomposite resists with enhanced properties. The infiltration of the metal or metal oxide can be carried out by vapor phase infiltration using the tools including but not limited to atomic layer deposition chamber and/or by liquid-based infiltration using solutions of metallic salts. The synthesized hybrid resists can then be subjected to the lithographic patterning and subsequent pattern transfer. The results support the basis for an easy access and cost‑effective development route to high‑performance lithography resists.

Advantages

• High resistance
• High sensitivity
• Cost‑effective
• Utilizes existing infrastructure

Application

• Lithography resists
• Computer chips