Resist processes for low-energy electron-beam lithography

Abstract

Accurate critical dimension control by using an azide/novolak resist process for electron-beam lithography Low-energy electron-beam lithography processes have been studied, a new resist system has been proposed, and preliminary tests have been performed. The interaction between electrons and e-beam resist and its effect on the exposure dose and the penetration depth of the electrons have been studied as a function of electron energy. A silylation process for low energy e-beam lithography has been tested and applied to a new bilayer resist scheme for low-energy electron-beam exposure.

Low-energy electron-beam lithography of hydrogen silsesquioxane

“…The loss of energy by an electron travelling a specific distance in a given material (resist) can be described by the Bethe formula [4]. A simple approximation shows that the loss of energy is proportional to 1/E (where E is the energy of electron) [5]:…”

“MBE‐Litho”: 3 nm‐thick amorphous GaAs oxidized thin film functioning as highly sensitive inorganic resist for EB lithography and oxide mask for selective processes

“…EBDW provides high resolution of the resist on a nanoscale, but its poor throughput has always been a challenge. For this problem, low energy EBDW using a resist thinner than 10 nm is one of the direct approaches due to electrons focusing at resist surface [2]. In addition, it can be expected to achieve better throughput and higher resolution by employing highly sensitive inorganic resist film.…”

The Interdependence of Exposure and Development Conditions when Optimizing Low-Energy EBL for Nano-Scale Resolution

“…High energy electrons also tend to penetrate deep in the substrate causing unwanted substrate damage, as well as give rise to a significant proximity effect. In contrast, ultra low voltage electrons in the 1-3 keV regimes deposit most of their energy within the resist, resulting in less substrate damage and decreasing dramatically the proximity effect (Lee et al, 1992;Schock et al, 1997). Furthermore, exposures employing voltages below 10 keV require lower doses roughly in proportion to the acceleration voltage (Schock et al, 1997).…”

“…In contrast, ultra low voltage electrons in the 1-3 keV regimes deposit most of their energy within the resist, resulting in less substrate damage and decreasing dramatically the proximity effect (Lee et al, 1992;Schock et al, 1997). Furthermore, exposures employing voltages below 10 keV require lower doses roughly in proportion to the acceleration voltage (Schock et al, 1997). Strong forward scattering of low energy electrons, which is routinely believed to be the major resolution-limiting factor, may alternatively be employed to create nanoscale three-dimensional profiles in the resist (Brünger et al, 1995).…”