Electron beam lithography—Resolution limits (original) (raw)
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Electron beam lithography: resolution limits and applications
Applied Surface Science, 2000
. We report on the resolution limits of Electron Beam Lithography EBL in the conventional polymethylmethacrylate Ž . PMMA organic resist. We show that resolution can be pushed below 10 nm for isolated features and how dense arrays of periodic structures can be fabricated at a pitch of 30 nm, leading to a density close to 700 Gbitrin 2 . We show that intrinsic resolution of the writing in the resist is as small as 3 to 5 nm at high incident electron energy, and that practical resolution is limited by the development of the resist after exposure and by pattern transfer. We present the results of our optimized process for reproducible fabrication of sub-10 nm lines by lift-off and 30-nm pitch pillar arrays by lift-off and reactive ion Ž . etching RIE . We also present some applications of these nanostructures for the fabrication of very high density molds for Ž . nano-imprint lithography NIL and for the fabrication of Multiple Tunnel Junction devices that can be used for single electron device applications or for the connection of small molecules. q 2000 Published by Elsevier Science B.V.
The Validation of Various Technological Factors Impact on the Electron Beam Lithography Process
Advances in Electrical and Electronic Engineering, 2021
One of the most significant processes in micro-and nanoelectronics technology is Electron Beam Lithography (EBL). This technique maintains a leading role in extremely high-resolution structures fabrication process with micro-and nanometer dimensions down to dozens of nanometers. The EBL is a highly complex process and determining fundamental technological factors that affect the final pattern shape is crucial. One of them is the used lithography system, consisting of a substrate and a polymer layer that affects the electron scattering effects. To obtain the required pattern geometry, it is also necessary to properly select the electron beam parameters for given materials. The aim of this work is to discuss the differences in the exposition process for various accelerating voltage (EHT) values. Additionally, the investigation of geometry features and the impact of the exposure dose and the structure dimensions on the final absorbed energy distribution profile in the resist layer is presented and discussed. Numerical studies, using CASINO software and Monte Carlo method, are presented to compare the energy distribution in the polymer that affects the structure formation in the resist layer.
Resolution Limits of Electron-Beam Lithography toward the Atomic Scale
Nano Letters, 2013
We investigated electron-beam lithography with an aberration-corrected scanning transmission electron microscope. We achieved 2 nm isolated feature size and 5 nm half-pitch in hydrogen silsesquioxane resist. We also analyzed the resolution limits of this technique by measuring the point-spread function at 200 keV. Furthermore, we measured the energy loss in the resist using electron-energy-loss spectroscopy.
Electron beam lithography using chemically-amplified resist: Resolution and profile control
Microelectronic Engineering, 1996
The effect of post exposure bake and softbake conditions on the sensitivity of AZPN114 has been investigated experimentally. A bilayer system for undercut structures has been achieved using two layers of AZPN114 with different softbake temperatures. A single layer of AZPN1 i4 has also been used to produce undercut and tailored resist profffles by two different multiple exposure strategies at different beam energies.
AIP Conference Proceedings, 2016
In this work, a statistical process control method is presented showing the accuracy and the reliability obtained with of PMMA E-resist AR-P 672, using an Elphy Quantum Electron Beam Lithography module integrated on a FE-SEM Zeiss Auriga instrument. Reproducible nanostructures with an high aspect ratio between e-resist thickness and width of written geometric structure are shown. Detailed investigation of geometry features are investigated with dimension in the range of 200 nm to 1 m. The adopted method will show how tuning the Area Dose factor and the PMMA thickness it was possible to determine the correct and reproducible parameters that allows to obtain well defined electron-beam features with a 4:1 aspect ratio. Such high aspect ratio opens the possibility to realize an electron-beam lithography lift-off process by using a standard e-beam resist.
Electron beam lithography at 10keV using an epoxy based high resolution negative resist
Microelectronic Engineering, 2007
The behaviour of a new epoxy based resist (mr-EBL 6000.1 XP) as a negative resist for e-beam lithography is presented. We demonstrate that it is possible to define sub-100 nm patterns when irradiating thin (120 nm) layers of resist with a 10 keV electron beam. The dependence of resolution and remaining thickness on electron dose, electron energy and photo acid generator (PAG) content is determined. After the electron beam lithography process, the resist is used as a mask for reactive ion etching. It presents a good etch resistance, that allows transfer of patterns to the substrate with resolution below 100 nm.
High resolution electron beam lithography using ZEP-520 and KRS resists at low voltage
Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures, 1996
ZEP-520 and KRS resist systems have been evaluated as candidates for use in low voltage electron beam lithography. ZEP-520 is a conventional chain scission resist which has a positive tone for over two orders of magnitude in exposure dose. KRS is a chemically amplified resist which can be easily tone reversed with a sensitivity ϳ8 C/cm 2 at 1 keV. Both resist systems are shown to have sensitivities ϳ1 C/cm 2 for positive tone area exposures to 1 keV electrons. A decrease in contrast in 50 nm thick resist layers is seen when exposure voltage is lowered from 2 to 1 keV, indicating nonuniform energy deposition over the resist thickness. High resolution single pass lines have been transferred into both Si and SiO 2 substrates at both low and high voltages in each resist system without using multilayer resist masks. The ZEP-520 and KRS resists are shown to have resolutions of 50 and 60 nm, respectively, at 1 kV, within a factor of 2 of their high voltage resolutions under identical development conditions. A cusp shaped etch profile in Si allows high aspect ratio 20 nm wide trenches to be fabricated using these resists on bulk Si. Low voltage exposures have been used to pattern gratings with periods as small as 75 and 100 nm in ZEP-520 and KRS, respectively. Low voltage exposures on SiO 2 show no indications of pattern distortion due to charging or proximity effects.
Proximity correction of chemically amplified resists for electron beam lithography
Microelectronic Engineering, 1998
A simple experimental method has been developed to extract parameters of ~, I~ and q for proximity correction in electron beam lithography of chemically amplified resists. The method is based on the mcasurelnent of a series of isolated lines with different line widths exposed at a single exposure dose. The measured deviations from noininal line width are fitted into a function, from which the proximity' parameters arc obtained. Proximity parameters for AZPN114 negative chemically amplified resist were derived by the new method and improvements on pattern fidelity and CD control after proximity correction are demonstrated.
An advanced epoxy novolac resist for fast high‐resolution electron‐beam lithography
Aspects of the formulation of a highly sensitive cresol epoxy novolac-based chemically amplified negative resist ͑epoxy resist, EPR͒ and optimization of critical process parameters for high-resolution electron-beam lithography are reported. The bulk resist sensitivity ͑E 80 , dose for 80% thickness retention͒ is 0.9 C cm Ϫ2 at 40 kV. The effect of postapply bake and postexposure bake on resist sensitivity, contrast, and resolution are investigated and optimized for lithography up to the 0.1 m regime. The resist process is characterized by a good exposure dose latitude and relevant insensitivity to the variation of thermal processing conditions. Postexposure bake temperature variations in the 90-130°C range cause minimal change in sensitivity but remarkable change in contrast. Due to this behavior the resist process is not described satisfactorily by the reaction kinetic models commonly used to characterize chemically amplified resists of different chemistry.