Cryogenic Electron Beam Induced Chemical Etching

Abstract

Cryogenic cooling is used to enable efficient, gas-mediated electron beam induced etching (EBIE) in cases where the etch rate is negligible at room and elevated substrate temperatures. The process is demonstrated using nitrogen trifluoride (NF3) as the etch precursor, and Si, SiO2, SiC, and Si3N4 as the materials volatilized by an electron beam. Cryogenic cooling broadens the range of precursors that can be used for EBIE, and enables high-resolution, deterministic etching of materials that are volatilized spontaneously by conventional etch precursors as demonstrated here by NF3 and XeF2 EBIE of silicon.

Dynamic Pattern Formation in Electron-Beam-Induced Etching

“…We note that the new EBIE model is consistent with all results in the literature that were explained successfully by the conventional EBIE model [1,2,5,[34][35][36][37][38][39][40][41][42][43][44]47]. The scaling of etch rate with beam energy is the same because the secondary electron yield is proportional to the energy transferred from the beam to the surface atoms of the substrate.…”

“…(1) [2,5,[34][35][36][37][38][39][40][41][42][43][44]. However, the model can not explain the etch rate anisotropy seen in Fig.…”

Electron-Beam-Induced Deposition as a Technique for Analysis of Precursor Molecule Diffusion Barriers and Prefactors

“…Condensation (i.e. formation of multilayers rather than Langmuir adsorption defined by the term (1 − Θ) in Equation 1) was ignored in our analysis (however, the precursor condensation temperature is easy to find and avoid experimentally 13,30,31 ). More generally, the analysis presented here must be re-done for systems that do not exhibit Langmuir adsorption, and systems in which coverage-dependent phenomena such as adsorbate-adsorbate interactions are significant (i.e.…”

“…reagents) used in the deposition and etch reactions. [12][13][14][15][16][17][18][19][20][21] Molecular properties that can be measured are those that affect the rates of adsorption (e.g. sticking coefficients), desorption (energies and attempt frequencies), diffusion (barriers and pre-factors) and dissociation (cross-sections).…”

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.…”