TY - JOUR

T1 - Helium ion beam lithography and liftoff

AU - Rashid, Sabaa

AU - Walia, Jaspreet

AU - Northfield, Howard

AU - Hahn, Choloong

AU - Olivieri, Anthony

AU - Lesina, Antonio Calà

AU - Variola, Fabio

AU - Weck, Arnaud

AU - Ramunno, Lora

AU - Berini, Pierre

N1 - Funding Information: Financial support provided by Huawei Technologies Canada and the Natural Sciences and Engineering Research Council (NSERC) of Canada is gratefully acknowledged. The authors also acknowledge Dominic Goodwill and Eric Bernier from Huawei Technologies Canada for their assistance. Ewa Lisicka-Skrzek is gratefully acknowledged for her assistance with the layouts. A C L acknowledges the Bundesministerium für Buldung und Furschung under the Tenure-Track Programme, and the Deutsche Forschungsgemeinschaft under Germany’s Excellence Strategy within the Cluster of Excellence PhoenixD (EXC 2122, Project ID 390833453).

PY - 2021/6/4

Y1 - 2021/6/4

N2 - We introduce a helium ion beam lithography and liftoff process to fabricate arbitrary nanostructures. Exploiting existing high-resolution positive tone resists such as poly (methyl methacrylate) (PMMA), the process offers three significant advantages over electron beam lithography: (a) the exposing helium ion beam produces a high secondary electron yield leading to fast patterning, (b) proximity effects are negligible due to the low count of backscattered helium ions from the substrate, and (c) the process is transferrable with minimal alteration among different types of substrates (e.g. silicon, fused silica). The process can be used to pattern any material compatible with liftoff such as evaporated metals or dielectrics, and allows overlay of nanostructures precision-aligned to microstructures realised beforehand on the same substrate. The process is demonstrated for several PMMA thicknesses to liftoff different thicknesses of deposited material. Resolution trials are conducted to determine the limits of the process for each PMMA thickness. Isolated lines as narrow as 14 nm, and line-space gratings of 40 nm pitch (50% duty cycle), are produced as resolution tests by lifting off a 20 nm thick Au film. Nanostructures of aspect ratio up to ∼3:1 have been realised. Plasmonic nanoantenna arrays overlaid to microscale contacts are produced as device demonstrators, for which optical measurements are in excellent agreement with theory.

AB - We introduce a helium ion beam lithography and liftoff process to fabricate arbitrary nanostructures. Exploiting existing high-resolution positive tone resists such as poly (methyl methacrylate) (PMMA), the process offers three significant advantages over electron beam lithography: (a) the exposing helium ion beam produces a high secondary electron yield leading to fast patterning, (b) proximity effects are negligible due to the low count of backscattered helium ions from the substrate, and (c) the process is transferrable with minimal alteration among different types of substrates (e.g. silicon, fused silica). The process can be used to pattern any material compatible with liftoff such as evaporated metals or dielectrics, and allows overlay of nanostructures precision-aligned to microstructures realised beforehand on the same substrate. The process is demonstrated for several PMMA thicknesses to liftoff different thicknesses of deposited material. Resolution trials are conducted to determine the limits of the process for each PMMA thickness. Isolated lines as narrow as 14 nm, and line-space gratings of 40 nm pitch (50% duty cycle), are produced as resolution tests by lifting off a 20 nm thick Au film. Nanostructures of aspect ratio up to ∼3:1 have been realised. Plasmonic nanoantenna arrays overlaid to microscale contacts are produced as device demonstrators, for which optical measurements are in excellent agreement with theory.

KW - Helium

KW - Lithography

KW - Nanoantennas

KW - Nanofabrication

KW - Plasmons

UR - http://www.scopus.com/inward/record.url?scp=85108640404&partnerID=8YFLogxK

U2 - 10.1088/2399-1984/abfd98

DO - 10.1088/2399-1984/abfd98

M3 - Article

AN - SCOPUS:85108640404

VL - 5

JO - Nano Futures

JF - Nano Futures

IS - 2

M1 - 025003

ER -