Proceedings Article | 16 October 2019
KEYWORDS: Extreme ultraviolet lithography, Opacity, Photoresist materials, Line width roughness, Photoresist developing, Stochastic processes, Scanners, Electron beam lithography, High volume manufacturing, Chemically amplified resists
The development of an EUV photoresist to support high volume manufacturing remains a challenging issue, No material currently meets the combined resolution, sensitivity, and line width roughness (RLS) requirements. Furthermore defectivity issues arising from stochastic effects are becoming increasingly critical as pitches decrease. Whilst traditional chemically amplified resists will likely support the initial insertion, a wide range of materials options are being examined for future nodes [1–3], aiming to identify a photoresist that simultaneously meets RLS and defectivity requirements.
Irresistible Materials (IM) is developing novel resist systems based on the multi-trigger concept. In a multi-trigger resist multiple elements of the resist must be simultaneously activated to enable the catalytic reactions to proceed. In high dose areas the resist therefore behaves like a traditional CAR, whilst in low dose areas, such as line edges, the reaction is second-order increasing the chemical gradient. Effectively there is a dose dependent quenching-like behaviour built in to the resist, enhancing chemical contrast and thus resolution and reducing roughness, whilst eliminating the materials stochastics impact of a separate quencher.
The multi-trigger material previously presented [4, 5] consists of a base molecule and a crosslinker, which represent the resist matrix, together with a photoacid generator (PAG). MTR2 showed 16 nm half pitch lines patterned with a dose of 38 mJ/cm2, giving a LER of 3.7 nm on the NXE3300 [4]. Since then, research has been undertaken to improve this resist. In particular we are focusing on improving resist opacity and present initial results for the MTR262Z(D) resist formulation here. We have demonstrated semi-dense 16.9 nm CD lines patterned using the NXE EUV Scanner in MTR262Z(D) at a halfpitch of 20nm, and dose of 13 mJ/cm2, and lines with a CD of sub-13 nm patterned at 22.5 mJ/cm2 on a 16 nm halfpitch.
We also present work aimed at improving the LWR of the high opacity resist formulation at high resolution, particularly aimed below 16nm hp using dense lines when patterned using EUV lithography at the Paul Scherrer Institute, Switzerland. The material shows 13.3 nm lines on a 14 nm half pitch, with an LWR of 2.97 nm and dose of 26 mJ/cm2.
[1] Stowers, J. K., Telecky, A., Kocsis, M., Clark, B. L., Keszler, D. A., Grenville, A., Anderson, C. N., Naulleau, P. P., “Directly patterned inorganic hardmask for EUV lithography,” Proc. SPIE 7969, 796915 (2011).
[2] Krysak, M., Trikeriotis, M., Schwartz, E., Lafferty, N., Xie, P., Smith, B., Zimmerman, P., Montgomery, W., Giannelis, E., Ober, C. K., “Development of an inorganic nanoparticle photoresist for EUV, e-beam, and 193 nm lithography,” Proc. SPIE 7972, 79721C (2011).
[3] Cardineau, B., Del Re, R., Al-Mashat, H., Marnell, M., Vockenhuber, M., Ekinci, Y., Sarma, C., Neisser, M., Freedman, D. A., Brainard, R. L., “EUV resists based on tin-oxo clusters,” Proc. SPIE 9051, 90511B (2014).
[4] Vesters Y., McClelland A., Popescu C., Dawson G., Roth J., Theis W., de Simone D., Vandenberghe G., Robinson A.P.G, “Multi-trigger resist patterning with ASML NXE3300 EUV scanner,” Proc. SPIE 10586, (2018).
[5] Popescu, C., Kazazis, D., McClelland, A., Dawson, G., Roth, J., Theis, W., Ekinci, Y., Robinson, A.P.G., “High-resolution EUV lithography using a multi-trigger resist,” Proc. SPIE 10583, 10583-54 (2018)
