Electron Beam Induced Etching Research Articles

Kinetics of gas mediated electron beam induced etching

Electron beam induced etching (EBIE) is a high resolution, direct write, chemical dry etch process in which surface-adsorbed precursor molecules are activated by an electron beam. We show that nanoscale EBIE is rate limited through at least two mechanisms ascribed to adsorbate depletion and the transport of gaseous precursor molecules into an etch pit during etching, respectively. The latter has, to date, not been accounted for in models of EBIE and is needed to reproduce etch kinetics which govern the time-evolution of etch pits, EBIE throughput, and spatial resolution.

Zero‐energy SIMS depth profiling: the role of surface roughness development with XeF2‐based etching

AbstractTo obtain monolayer depth resolution in the zero‐energy SIMS concept, an almost atomically flat surface during the electron beam‐induced etching (EBIE) is crucial. However, the surface roughness observed with Si EBIE and XeF2 shows the same characteristics as observed during spontaneous etching of Si with XeF2. The subsurface fluorine concentration in a Si EBIE process (even in a mass transport limited regime) can influence the unactivated formation of the SiFx reaction layer as well, and therefore, contribute to observed roughness development. SiO2 EBIE leads to extreme pit formation due to preferential etching of Si at the SiO2/Si interface. In general, preferential etching can deteriorate or enhance the depth resolution as shown on a SiGe epilayer structure. Finally, the capabilities of zero‐energy SIMS are shown on an ultra‐shallow SiGe structure demonstrating a narrow surface transient and a very good depth resolution in the surface region. Copyright © 2010 John Wiley & Sons, Ltd.

Electron beam induced etching of silicon with SF6

Electron beam induced etching (EBIE) with SF6 precursor molecules has been demonstrated as an approach to induce localized etching of Si with an etch yield of approximately 0.003 atoms/incoming electron. Further understanding of the EBIE mechanisms is presented through an analysis of the influence of the different electron beam parameters (beam energy and electron flux) and the effect of the sample bias on the EBIE rate. It is demonstrated that the etch rate increases with decreasing beam energy and with increasing electron flux to a saturation value. The latter is explained by a transition from an electron flux density limited process (at low current densities) to a gas supply limited process (at high current densities). The authors also demonstrate that a large etch rate enhancement is obtained by applying a positive sample bias. This is explained within the frame of a model outlining the role of the low secondary energy electrons in the electron stimulated etching process.

Inhibiting spontaneous etching of nanoscale electron beam induced etching features: Solutions for nanoscale repair of extreme ultraviolet lithography masks

Electron beam induced etching (EBIE) is an important technique for repairing nanoscale defects on extreme ultraviolet (EUV) lithography masks as it provides excellent spatial resolution and etch selectivity while minimizing collateral damage to the mask. While EBIE itself is a complex process, a current problem with EBIE of the TaN EUV mask absorber layer using XeF2 is the spontaneous etching of repaired features during subsequent edits of the mask. This work explores three passivation techniques for controlling the spontaneous etching after an EBIE repair is made. An oxygen plasma was used to attempt to oxidize the TaN sidewalls, but it was not successful at stopping the spontaneous etching. An active electron beam induced passivation using water was successful at stopping the spontaneous etching. Also, simple adsorption of water molecules on the TaN sidewalls was successful at inhibiting spontaneous etching. The successful passivation strategies are affected by subsequent scanning electron beam imaging. It was determined that the electron beam activated passivation can be damaged by electron beam imaging in the presence of residual XeF2 on the surface. Also, the adsorbed water passivation strategy is susceptible to electron induced desorption of the water.

Controlled focused electron beam-induced etching for the fabrication of sub-beam-size nanoholes

Sub-beam-size focused electron beam-induced etching of amorphous carbon membranes was achieved. The size of the tungsten filament generated electron beam was determined from the in situ stage current monitoring and verified by knife edge measurements. The in situ time resolved stage current measurements as an end point detection allowed the fabrication of nanoholes with a diameter of sub-20nm, corresponding to 20%–40% of the full width at half maximum of the incident beam.

High resolution radially symmetric nanostructures from simultaneous electron beaminduced etching and deposition

Electron beam induced etching (EBIE) and deposition (EBID) are promising fabricationtechniques in which an electron beam is used to dissociate surface-adsorbed precursormolecules to achieve etching or deposition. Spatial resolution is normally limited by theelectron flux distribution at the substrate surface. Here we present simultaneous EBIE andEBID (EBIED) as a method for surpassing this resolution limit by using adsorbatedepletion to induce etching and deposition in adjacent regions within the electron fluxprofile. Our simulation results indicate the possibility of growth control of radiallysymmetric nanostructures at the sub-1 nm length scale on bulk substrates. Thetechnique is well suited to the fabrication of ring-shaped nanostructures such as thoseemployed in plasmonics, sensing devices, magneto-optics and magnetoelectronics.

Focused, Nanoscale Electron-Beam-Induced Deposition and Etching

Focused electron-beam-induced (FEB-induced) deposition and etching are versatile, direct-write nanofabrication schemes that allow for selective deposition or removal of a variety of materials. Fundamentally, these processes are governed by an electron-induced reaction with a precursor vapor, which may either result in decomposition to a solid deposit or formation of a volatile etch by-product. The ability to induce such localized reactions by placement of a nanometer-sized focused electron probe has recently drawn considerable attention. In response, we have reviewed much of the relevant literature pertaining to both focused electron-beam-induced etching and deposition. Because these nanoscale processing techniques are still in their relative infancy, a significant amount of scientific research is being conducted to understand, and hence improve, the processes. This article summarizes the associated physics of electron-solid-vapor interactions, discusses related physical processes, and provides an introduction to electron-beam-induced etching (EBIE) and electron-beam-induced deposition (EBID). Additionally, specific applications of FEB-induced processes are discussed and several FEB computer model and simulation results are reviewed.