Lithographic properties of amorphous solid water upon exposure to electrons

• Published in: Applied surface science Vol. 539; p. 148265
• Main Authors: Wu, Shan, Zhao, Ding, Yao, Guangnan, Hong, Yu, Qiu, Min
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.02.2021
• Subjects: Amorphous solid water; E-beam patterning; Electron resist; Ice lithography; Surface hydrophilicity; Electron resist; E-beam patterning; Ice lithography; Surface hydrophilicity; Amorphous solid water
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2020.148265

[Display omitted] •Amorphous solid water acts as a unique positive-tone electron resist.•Ice thickness removed by electron irradiation has a strong linear dependence on applied electron doses.•Ice formed on hydrophilic surfaces resists more irradiation than on the hydrophobic.•Ice nanodots and “micro-snowflakes” are attained after e-beam patterning.•Ice can be used to regulate lithographic properties of conventional electron resists. Amorphous solid water (ASW) formed by vapor deposition at cryogenic temperatures acts as an emerging competitive electron resist with virtues like direct patterning and easy removal. In this work, we systematically study the properties of the ASW resist and assess its performance for lithographic applications. Dose curves show that ASW has a low contrast of ~1.6 and it is barely affected by the incident electron energy. Ice elimination is almost linear to applied electron doses. The calculated rate is around 30 μm3/μC at 10 kV, implying approximately seven electrons remove one water molecule in this case. The minimum linewidth of 12 nm is obtained on a 120-nm-thick ASW film and refined nanostructures such as ice nanodots and “micro-snowflakes” are also presented. Finally, we perform e-beam exposure on a bilayer configuration of ASW/PMMA resist and provide an alternative way to regulate lithographic properties of conventional electron resists.