Nanostructure fabrication in silicon using cesium to pattern a self-assembled monolayer

Abstract

This letter describes the formation of nanometer-scale features in a silicon substrate using a self-assembled monolayer ͑SAM͒ of octylsiloxane on silicon dioxide as a resist sensitive to a patterned beam of neutral cesium atoms. The mask that patterned the atomic beam was a silicon nitride membrane perforated with nm and m scale holes, in contact with the substrate surface. In a two-step wet-chemical etching process, the pattern formed in the SAM was transferred first into the SiO 2 layer and then into an underlying silicon substrate. This process demonstrated the formation of silicon features with diameter ϳ60 nm.

Negative resist behavior of neutral sodium atoms deposited on self-assembled monolayers

“…One possibility is that a chemical reaction occurs between the highly reactive alkalis and the monolayer, perhaps involving the bond at the Au/SAM interface. Such a process is consistent with the positive tone resist behavior previously reported [5][6][7] using Cs and alkanethiol SAM resists. Although briefly discussed, 6 no detailed study of the interaction of Na atoms with SAM resists has been performed.…”

Atom Lithography: Fabricating Arrays of Silicon Microstructures Using Self-Assembled Monolayer Resist and Metastable Helium Beam

“…This damage can cause a characteristic surface change from hydrophobic to hydrophilic or a molecular structural change from condensed to cross-linked, which consequentially affect the etching process in the fabrication of the micro-or nanostructure, resulting in the positive and negative pattern transfers, respectively. The typical micropatterning with sub-100 nm resolution on a silicon substrate covered with a SiO 2 or Au layer has been achieved successfully [10,21,22,28,29]. Most of these studies are conducted through multistep etching processes using the cover layers as intermediate masks.…”

“…With these unique advantages, the atom lithography with neutral MAB and high-resolution SAM resist makes it possible to achieve nanolithography and provides a potential way in manufacturing structures at a largescale based on micro-and nanoscale features. During the past fifteen years, considerable attention has also been given to the investigation of the mechanism of metastable atom lithography and microfabrication with different resolutions on various substrates, such as gold, silicon, silicon oxide, and mica [10,[19][20][21][22][23][24][25][26][27][28][29]. Direct evidence of the emission of H + and CH x + from the SAM on the Au(111) surface under the irradiation of a metastable helium atom beam (He*-MAB) at thermal energy supports the interpretation that the SAM is damaged through the interaction between the outermost surface of the SAM and the metastable atoms.…”

“…Most of these studies are conducted through multistep etching processes using the cover layers as intermediate masks. For example, in the He*-MAB lithography with dodecanethiol-SAM [10,21,22], a Au/Ti coating layer is used to create an intermediate mask on silicon substrate by the first etching process, and then, the intermediate mask pattern is transferred to silicon substrate by the second etching process. It is very interesting to directly transfer negative and positive patterns of SAM induced by He*-MAB into a silicon substrate without metal/oxide coating layer to fabricate arrays of micro-and nanostructures.…”

Atomic nanolithography patterning of submicron features: writing an organic self-assembled monolayer with cold, bright Cs atom beams

“…An alternative to direct deposit, writing "resists" on substrates in neutral atom nanolithography provides both high sensitivity and high resolution [7,8]. The resists that show the best response to neutral atom lithography are those of self-assembled monolayers (SAMs) of organic molecules.…”