Combined Focused Ion Beam Research Articles

Focused-Ion Beam and Electron Microscopy Analysis of Corrosion of Lead-Tin Alloys: Applications to Conservation of Organ Pipes

AbstractAcross Europe, lead-tin alloy organ pipes are suffering from atmospheric corrosion. This deterioration can eventually lead to cracks and holes, preventing the pipes from producing sound. Organ pipes are found in compositions ranging from >99% Pb to >99% Sn. For very lead-rich (>99% Pb) pipes, organic acids emitted from the wood of organ cases have previously been identified as significant corrosive agents. In order to study the role of alloy composition in the susceptibility of pipes to organic acid attack, lead-tin alloys containing 1.2-15 at.% Sn were exposed to acetic acid vapors in laboratory exposure studies. Corrosion rates were monitored gravimetrically, and corrosion product phases were identified using grazing incidence angle X-ray diffraction. In a new method, focused-ion beam (FIB) cross-sections were cut through corrosion sites, and SEM and WDX were used to obtain detailed information about the morphology and chemical composition of the corrosion layers. The combination of FIB and SEM has made it possible to obtain depth information about these micron-scale layers, providing insight into the influence of acetic acid on alloys in the 1.2-15 at.% Sn range.

Rapid and three-dimensional nanoimprint template fabrication technology using focused ion beam lithography

The characteristics of focused ion beam (FIB) lithography for spin-on-glass (SOG) and PMMA resists were investigated. These resists have high sensitivity around 1 μC/cm 2 and their depth gradations were obtained by using less than 1 μC/cm 2. In particular, FIB lithography working with SOG resists can be used for speedy fabrication of three-dimensional (3D) nanoimprint template. Furthermore, this combination of FIB and SOG has the potential for alternative to EB cutting which is the next generation media mastering technique. Using fabricated SOG template, UV-nanoimprint lithography was carried out and replicated pattern with 59.8 nm gap was obtained.

Exposure and characterization of nano-structured hole arrays in tapered photonic crystal fibers using a combined FIB/SEM technique

This paper presents a technique to expose and characterize nano-structured hole arrays in tapered photonic crystal fibers. Hole array structures are examined with taper outer diameters ranging from 12.9 microm to 1.6 microm. A combined focused ion beam milling and scanning electron microscope system was used to expose and characterize the arrayed air-silica structures. Results from this combined technique are presented which resolve hole-to-hole pitch sizes and hole diameters in the order of 120 nm and 60 nm, respectively.

HVEM study of crack-tip dislocations in Si crystals prepared by FIB and twin-blade cutting method

Crack-tip dislocations in silicon crystals have been examined by using high-voltage electron microscopy. Cracks were introduced by the Vickers indentation method at room temperature and the indented specimens were annealed at high temperatures to induce dislocations around crack tips under the presence of residual stress due to the indentation. A selected area around a crack tip was thinned by a focused ion beam (FIB) technique. Specimens were thinned in advance by a twin-blade cutting (TBC) method, which is a simple cutting process for saving FIB machine time. A combination of FIB and TBC can be a useful thinning procedure for the efficient preparation of transmission electron microscopy specimens. Characteristic dislocation structures were observed around the tip of a crack, aiding the elucidation of dislocation processes, which is essential to increase the fracture toughness of materials.

Preparation of transmission electron microscopy cross-section specimens of crack tips using focused ion beam milling.

The preparation of transmission electron microscope (TEM) thin foil specimens from metal alloys containing cracks is usually thwarted by the difficulty in preventing preferential erosion of material along the flanks and at the tips of cracks. Recent developments in focused ion beam (FIB) micromachining methods have the potential to overcome this inherent problem. In this article we describe the development of new procedures, one using FIB alone and the other using a combination of FIB with more conventional ion milling to generate TEM specimens that largely retain the microstructural information at stress corrosion cracks in austentic alloys. Examples of corrosion product phase identification and interfacial segregation are included to verify that detailed information is not destroyed by ion bombardment during specimen preparation.

Combined focused ion beam deposition system and scanning probe microscope for metal nanostructure fabrication and characterization

We have developed a combined focused ion beam deposition machine and scanning probe microscope which has been used to fabricate and characterize metal nanoparticles entirely within a high-vacuum environment. The focused ion beam section is fitted with a retarding-field stage which allows the landing energy of ions to be adjusted from ∼20 to over 400 eV. The microscope has been adapted to enable the probe to be directed to the localized deposits so that the physical structure of the deposits and the electrical properties can be measured in situ.

Focused ion beam technology

Focused ion beam (FIB) technology has the advantage of being a maskless process compatible with UHV processing. This makes it attractive for use in in situ processing and has been applied to the fabrication of various mesoscopic structures. The present paper reviews these results whilst putting emphasis on in situ processing by a combined FIB and molecular beam epitaxy system. The typical performance of present FIB systems is also presented. In order to utilize the potential advantages of FIB processing, reduction of damage and improvement of throughput are important, and much effort has been devoted to developing processing techniques which require a reduced dose. The importance of low-energy FIB is discussed.

Performance of a combined focused ion and electron beam system

In order to characterize electron and ion beam induced etching and deposition parameters in a single system a combined focused ion beam (FIB) and electron beam (EB) column has been developed. This system has both an electron gun and a FIB gun with a gallium liquid metal ion (LMI) source integrated on an objective lens and deflector assembly shared by both sources. A cylindrical electrostatic prism was used to position the electron beam on the final lens axis. We have optimized the EB crossover location to minimize chromatic blurring induced by the prism. In addition, the system was configured with a common retarding lens below the objective lens to permit low energy ion and electron beam experimentation. This lens provided the system with an energy range from 1 to 25 keV. The theoretical minimum probe diameters at 1 keV are 20 and 300 nm, respectively, for the electron and focused ion final beam diameters. We will present the experimental scanning electron microscopy (SEM) mode and scanning ion microscopy (SIM) mode image results which compare well to the theoretical predictions at 1 keV.