Electron Beam Induced Writing of Corrosion Protection

Abstract

Carbon patterns ͑C layers͒ were deposited on iron surfaces by electron-beam induced contamination decomposition writing. Chemical and electrochemical etching were used to investigate the protective nature of these C layers against metal corrosion. The results clearly show that E-beam written C patterns can be very corrosion resistant. The key factor controlling the degree of protectiveness, under given conditions of attack, is the deposition dose, i.e., the layer thickness. For sufficiently high doses, the iron surface can be completely protected against corrosion. Therefore, this direct masking approach opens new perspectives for highly precise and controlled local corrosion suppression.In recent years, carbon layers on metallic surfaces have found increasing interest to provide new methods for corrosion protection as well as to alter and tailor mechanical properties of surfaces.For example, it has been reported that corrosion resistance of aluminum and aluminum alloys can be modified significantly by carbon evaporation and carbon sputtering under concurrent argon ion bombardment. 1 Aluminum films covered by a thin (Ͻ5 nm) carbon film exhibited extreme corrosion resistance to concentrated acids ͑hydrofluoric acid and phosphoric ϩ nitric acid͒ 2 and to 3.5 wt % NaCl solution. 3,4 Mechanical durability and corrosion resistance for magnetic layers based on Co-alloys were obtained by covering the material with amorphous hydrogenated carbon doped with nitrogen. 5,6 This is particularly significant for the protection of magnetic hard drives.A well-known case of electron beam-induced patterning is the formation of carbon-rich contamination layers in scanning electron microscopes ͑SEMs͒. The E-beam activates reactions of the residual hydrocarbons ͑molecules from the pump oil͒ in diffusion pumped systems to create a highly cross-linked hydrocarbon deposit. In other words, the E-beam cracks the thin layer of hydrocarbon molecules condensed at the sample surface at the point of impact of the E-beam. In previous work, it has been demonstrated that such C patterns can be exploited to block completely and selectively electrochemical deposition of metals at semiconductor surfaces. 7,8 This E-beam induced C-deposition technique has been used to produce metal structures on semiconductor surfaces in the sub-100 nm range 9 as well as the selective formation of light emitting porous Si. 10 The present work explores the feasibility of using such C layers produced by contamination writing in a SEM to suppress corrosion of iron at the treated locations. This would provide a C-masking technique to protect specific surface locations in a highly controlled manner and with a very high lateral resolution. ExperimentalIron ͑99.5%͒ samples were mechanically polished using 0.1 m diamond paste finish. Subsequently, the samples were degreased by sonicating in ethanol, rinsed with deionized ͑DI͒ water and dried in an argon stream. To achieve E-beam induced deposition of the C patterns, the samples were irradiated in a JEOL 6400 SEM. Single E-bea...

Gas-assisted focused electron beam and ion beam processing and fabrication

“…Already in the 1990s FEB contamination deposits were used as resist for the fabrication of 8 nm tungsten line features 7 and continue to be used as local anticorrosion masks for iron 528 or as electrodeposition masks 529,530 and wet etch masks for ͑110͒ Si ͑Ref. 531͒ or dry etch masks.…”

Electron-Beam-Induced Carbon Contamination on Silicon: Characterization Using Raman Spectroscopy and Atomic Force Microscopy

“…The modification of metallic surface reactivity may even be used to advantage. For example, Sieber et al (2003) used it as a highly precise and controllable direct masking approach to corrosion suppression, which may have some advantage if localized microtreatment is desired.…”

Organic monolayers as resist layers for Cu deposition on Si (111) surfaces

“…The same source showed that for high doses, formation of diamond-like-carbon (DLC) could take place [31]. In earlier work this was confirmed by corresponding Raman spectra [32]. Hindrance effect of Cu deposition on samples treated with high e-beam doses was found to be efficient also for immersion plating technique.…”