Dynamic Surface Site Activation: A Rate Limiting Process in Electron Beam Induced Etching

Abstract

We report a new mechanism that limits the rate of electron beam induced etching (EBIE). Typically, the etch rate is assumed to scale directly with the precursor adsorbate dissociation rate. Here, we show that this is a special case, and that the rate can instead be limited by the concentration of active sites at the surface. Novel etch kinetics are expected if surface sites are activated during EBIE, and observed experimentally using the electron sensitive material ultra nanocrystalline diamond (UNCD). In practice, etch kinetics are of interest because they affect resolution, throughput, proximity effects, and the topography of nanostructures and nanostructured devices fabricated by EBIE.

Advances in gas-mediated electron beam-induced etching and related material processing techniques

“…The technique is analogous to focused ion beam processing [6][7][8][9][10][11], but avoids damage, staining and redeposition artifacts caused by ion bombardment. EBIE is realized using gaseous precursors such as H 2 O, O 2 , NH 3 , XeF 2 , Cl 2 and SF 6 , which have been used to volatilize a wide range of materials, including graphene [12], single [13] and multi-walled [14] C nanotubes, amorphous carbon [15][16][17][18], single crystal [19][20][21][22] and nano-crystalline [23] diamond, Si, SiO 2 , Si 3 N 4 , Cr, Ti, TaN and photoresist [24][25][26][27][28][29][30][31][32][33][34][35][36][37][38]. Historical overviews and reviews of the EBIE technique and the underlying chemical pathways can be found in references [1][2][3][4][5].…”

Localized chemical switching of the charge state of nitrogen-vacancy luminescence centers in diamond

“…Chemically active surface regions have previously been used as catalytic templates for electron beam directed, room temperature chemical vapor deposition, [1][2][3] and to locally accelerate the etch rate of diamond. 4 Here we present a beam-directed chemical technique for controlling the charge states of luminescence centers in semiconductors. The diamond NV center, comprised of a substitutional nitrogen atom adjacent to a carbon vacancy, is the subject of intense research into qubits for use in quantum computing, 5 markers for live cell imaging, fields.…”

Electron beam induced etching of carbon

“…The UNCD substrates were ⇠ 1.7 µm films grown on silicon by hot filament chemical vapor 23,36 . The eCell shown in Fig.…”

“…because it improves the degree of control over the vacuum chamber environment 25,38 , and enables EBIE experiments to be performed with a high degree of reproducibility 23 . Two liquid nitrogen (LN) cold traps were installed, one on a gas delivery line and one inside the eCell (see Fig.…”

“…EBIE has been used to etch numerous carbon materials including graphene 10,[12][13][14][15] , carbon nanotubes [16][17][18][19] , diamond 11,[20][21][22] , ultra nano-crystalline diamond 23 (UNCD), and amorphous carbon-rich nanowires 24,25 and films 18,24,[26][27][28] . At low electron beam energies ( 30 keV), where atomic displacements by knock-on collisions between electrons and carbon are negligible 14,29,30 , the removal of carbon is typically attributed TABLE I.…”