Focused Ion Beam (FIB) system is equipment used to make a wide variety of micro and Nano structures. Structures can be created using various materials by irradiating focused gallium ion beam on to the surface of specimens and by sputtering, etching and ion beam induced deposition. In order to realize greater diversity for nano construction by using the FIB system, we have developed technologies incorporating:

- Built-in pattern signal generator

- Multiple Gas Unit for gas assisted etching and beam induced deposition

- A precision wheel for the stage.

This latest FIB system has a narrow Ion beam with a diameter of better than 4nm. Beam current is controlled from 0.15pA to 20nA. These performances contribute significantly to the study 3D structures fabrication and modification.

We have developed and successfully demonstrated a protocol for mounting and electrical grounding of a butterfly wing scale using a series of localized electron- and ion-beam assisted Pt depositions in the dual-beam Focused Ion Beam (FIB)-SEM system. This method eliminates introduction of silver paint or other typical mounting materials, along with their chemistries, and produces a stable structure for FIB cross-sectioning, electron imaging, chemical analysis by Energy Dispersive Spectrometry (EDS) and/or Auger Electron Spectroscopy (AES), and FIB milling for 3-D reconstruction.

Aperture arrays were fabricated in 1.0µm thick gold films supported on 20nm thick silicon nitride membranes. Lithographic milling strategies in gold were evaluated through the use of in-situ sectioning and high resolution SEM imaging with the UWO CrossBeam FIB/SEM. A successful strategy for producing a 250nm diameter hole with sidewalls approaching vertical is summarized.

The response of crystalline Ge to indentation has been studied over a range of maximum loads. At a certain load, an unusual ‘giant pop-in’ event occurs, in which a discontinuous extension of >1 μm is observed in the force-displacement curve. In such cases, load release curves show a pronounced ‘elbowing’ response, leading to increased depth recovery. TEM and Raman microspectroscopy revealed the presence of amorphous material in the residual impression. To examine cracking, a sequence of cross-sections was milled through the indent and images taken using an automated method (the ‘slice-and-view’ method). Using 3-D reconstruction software, the data was segmented and reconstructed into a 3-dimensional representation of the cracks around the indent. Applying this technique to indents featuring a giant pop-in, it was deduced that the inelastic elbowing observed was a bending response of material detached by lateral cracking. The giant pop-in is attributable to material removal, caused by lateral cracks formed during loading.

Recent advances in the 2-beam focused ion beams technology has enabled researchers to not only perform high-precision nanolithography and micro-machining, but also to apply these novel fabrication techniques to investigating a broad range of materials' properties at the sub-micron and nano-scales. In our work, the FIB is utilized in manufacturing of sub-micron cylinders, or nano-pillars, as well as of TEM cross-sections to directly investigate plasticity of metals at these small length scales. Gold nano-pillars, ranging in diameter between 200 nm and several micrometers were fabricated from bulk gold and epitaxial gold films on MgO substrates and subsequently compressed using a Nanoindenter fitted with a custom-fabricated diamond flat punch. We show convincingly that fundamental mechanical properties like flow stress, yield strength, and stiffness strongly depend on the sample size, as some of our smaller specimens were found to plastically deform in uniaxial compression at stresses as high as 800 MPa, a value ~50 times higher than for bulk gold.

We believe that these high strengths are hardened by dislocation starvation. In this mechanism, once the sample is small enough, the mobile dislocations have a higher probability of annihilating at a nearby free surface than of multiplying and being pinned by other dislocations. Therefore, plasticity is accommodated by the nucleation and motion of new dislocations rather than by interactions of existing dislocations, as is the case for bulk crystals. To validate this mechanism, direct observation of dislocations was accomplished by utilizing the Omniprobe micromanipulator, coupled with FIB-milling and Pt deposition, for fabrication of site-specific TEM specimens. Preliminary TEM images show the lack of mobile dislocations in deformed pillars, which agrees with the proposed dislocation starvation mechanism, as discussed.

The International Technology Roadmap for Semiconductors (ITRS) identifies the shrinking of lithography critical dimensions (CDs) as one of biggest challenges facing the semiconductor industry as it progresses to smaller geometry nodes. Nanolithography, the patterning of masking CDs below 100nm, enables both nanoscale wafer processing and the exploration of novel nanotechnology applications and devices.

Focused Ion Beam (FIB) lithography has significant advantages over alternative nanolithography techniques, particularly when comparing resist sensitivity, topography effects, proximity effects and backscattering. FIB lithography uses the implantation of ions, such as Ga+, in its masking process. Ions implanted into resist in this manner typically have shallow penetration depths (<100nm for Ga+), and this would typically require the use of very thin resist layers during processing. This is often incompatible with subsequent fabrication steps such as plasma etching, where thicker resist layers are usually required to facilitate etch selectivity. Top surface imaging (TSI) is a solution to this problem.

When compared with conventional microelectronic lithography, nanolithography techniques such as EUV, electron beam and nanoimprint lithography require expensive process equipment and the use of non-standard process materials.

The 2-step negative resist image by dry etching (2-step NERIME) process is a FIB TSI scheme developed for DNQ/novolak based resists, and involves FIB exposure of resist with Ga+, followed by O2 plasma dry development using reactive ion etching. The 2-step NERIME process uses equipment sets and materials commonly found in microelectronic device fabrication (FIB tool, O2 plasma etcher, DNQ/novolak resists), and provides a low-cost and convenient nanolithography option for proof-of-concept nanoscale processing.

To be of practical use, a nanolithography scheme must be capable of patterning nanoscale resist features over substrate topography while retaining resist profile control. The nanolithography scheme must also integrate with subsequent plasma etch processing steps that etch various material films such as metals, Si, SiO2, SiN. The 2-step NERIME FIB TSI process has been used to successfully pattern nanoscale (40nm-90nm) resist features on planar and topography substrates. We have also demonstrated sub-100nm etched features on topography substrates using the 2-step NERIME process, reporting 80nm Polycide and TiN etched features, and 90nm Ti etched features, that exhibit excellent profiles and minimal line edge roughness (LER).

It is expected that the 2-step NERIME FIB TSI process will be further extended to etch sub-40nm features over topography substrates. The nanoscale etched features will be used to explore proof-of-concept geometry shrink & novel structures, with many possible applications, including NEMs and nanosensors research and development.

Through-holes of diameter 35nm and larger were milled in 100nm thick silicon nitride windows by focused ion beam milling. The holes were sized to optimize capture of gold nanoparticles from a liquid suspension. The colloidal suspensions of gold particles were deposited onto the membrane and drawn through the holes by capillary forces. Efficient, single particle filling is demonstrated for both 100nm and 250nm diameter particles indicating that once a hole is filled, flow can be effectively blocked. We show that lithographically defined arrays of colloidal gold can be achieved with >98% filling.

Focused ion beams (FIBs) provide maskless prototyping of 2-D and 3-D micro- and nano-structures for many applications in optics, electronics, and medicine. In many situations, the chemical enhancement of the FIB sputtering process is used to increase the selectivity and removal rate of different materials.

In this study, Ti, TiO2, and TiN thin films of different origin were patterned using Ga+ FIB without or with chemical enhancement (or gas assisted etching, GAE). The effects of ion beam parameters and gas ambient on the sputtering yields, etching selectivity, roughening at the film/substrate interface, sub-micron and nano-scale patterning of these materials were investigated.

Several gases, including XeF2, CO2, chlorine, bromine, and oxygen, were employed. The largest increase of the sputtering yield was achieved with XeF2 gas, whereas CO2 and oxygen depleted the sputtering rate. Among all gases tested, the Br2 FIB GAE produced the best uniformity of the material removal. It was found that the use of bromine gas provides the best selectivity between the titanium oxide and pure titanium or its nitride.

Medium energy (30 keV) focused gallium ion beam exposure of silicon results in a compressive in-plane stress with a magnitude as large as 0.4 GPa. Experiments involve uniform irradiation of thin polysilicon microcantilevers (200 micron length) over a range of dose from 1 x 1016 to 2 x 1018 ions/cm2. The radii of curvature of microcantilevers are measured using white light interferometry before and after each exposure. The residual stress is determined from these radii and other measured properties using Stoney's equation. The large residual stress is attributed to ion beam damage, microstructural changes and implantation.

For the investigation of the adhesion of mammalian cells on a semiconductor biosensor structure, nerve cells on silicon neurochips were prepared for scanning electron microscopy investigations (SEM) and cross-sectional preparation by focused ion beam technology (FIB). The cross-sectional pattern demonstrates the focal adhesion points of the nerve cells on the chip. Finally, SEM micrographs were taken parallel to the FIB ablation to investigate the cross section of the cells slice by slice in order to demonstrate the spatial distribution of focal contact positions for a possible three-dimensional reconstruction of the cell-silicon interface.

Fabrication of high index contrast waveguide stacks for biosensing and other applications require nanometer scale thickness control. Nanoscale dielectric films from electron-beam evaporation can be difficult to obtain due to the resulting porosity and poor stoichiometry of the films. An alternative approach is the reactive deposition of the film from a metal source in the presence of oxygen ions. Using spectroscopic ellipsometry, we have shown that greater control over thickness and index of refraction of silicon dioxide depositions can be obtained through reactive depositions as compared to depositions from SiO2 dielectric source material itself. Through Fourier Transform Infrared Spectroscopy (FT-IR), the Si-O in-phase stretching peak at 1078 cm-1 can be traced, allowing us to determine the stoichiometry of the film.

The effects of performing depositions of aluminum oxide dielectric source material in the presence of oxygen ions has also been investigated. Through the use of the oxygen ion source, greater control over index of refraction and optical losses has been observed. By controlling ion source parameters, the aluminum oxide films’ index of refraction can be engineered within a range of 1.58 to 1.64, and waveguide losses can be reduced to as low as 2.0 dB/cm.

Electrodeposited nickel-tungsten alloys are being considered as a candidate material for components for microelectromechanical systems (MEMS) fabricated by the LIGA (German acronym for lithography, electrodeposition, and forming) technology. In spite of having a useful range of properties including; hardness and strength, better tribological and chemical resistance and improved high temperature resistance as compared with the conventionally used electrodeposited Ni, these alloys possess certain brittleness. In this study, the fracture toughness of Ni-17.5 at%W alloy microcantilever beams (dimension: 60µm × 20µm x 14µm) fabricated by UV lithography and electrodeposition and notched by focused ion beam machining is investigated. Load was applied to the beams using a nanoindenter, which also allowed accurate positioning of the sample. Fracture toughness was calculated from the fracture load assuming a linear elastic behaviour. The Ni-W alloy beams were found to possess a mean fracture toughness of 2.97 MPa √m. The fracture toughness of Ni-W alloy is found to be higher than that of Si - another important MEMS material, but considerably lower than that of electrodeposited nickel and nickel base alloys.

The in-situ lift-out method for TEM sample preparation, based on the use of a chamber-mounted nanomanipulator and FIB induced material deposition, has proven its effectiveness over the last several years. The time-efficiency introduced by this method is one reason for its success and rapid adoption within the semiconductor industry. Improvements to in-situ TEM lift-out preparation have been pursued to further improve sample processing time. One area targeted has involved methods to enable rapid in-situ probe tip replacement without having to remove the probe shaft from the vacuum chamber. This paper describes an in-situ probe tip replacement system that successfully solves this problem.

We report recent development of a three-probe micromachined nanomanipulator for manipulation and in-situ characterization of nanomaterials in scanning electron microscope (SEM). The nanomanipulator consists of three independent probes having thermal bimetallic actuators and nanoscopic end-effectors. Nanoscale end-effectors with sub-100-nm spacing are created using focused ion beam (FIB) milling to directly interface with nanoscopic objects (e.g., nanotubes, nanowires). Handling of individual carbon nanotubes (CNTs) was successfully realized with the nanomanipulator in an SEM.

Focused 30keV gallium ion beam, single-pixel drilling combined with backside particle detection is used to fabricate pores having exit diameters as small as ~11 nm in 200 nm-thick silicon nitride membranes. The backside channelplate detector response obtained about the onset of breakthrough is interpreted by plan-view transmission electron microscopy investigations of hole morphology. Immediately prior to breakthrough, there is a rise in detector signal as the local membrane thickness is reduced. This likely occurs as a result of ion transmission and, possibly, forward sputtering. At the dose required for breakthrough a maximum detector signal is obtained thus providing a potential method for end point detection. The focused ion drilling technique avoids broad area beam exposure methods that are often used to reduce hole diameter to nanometer dimension. In addition, the current approach overcomes difficulties in determining a required dose for breakthrough such as those that arise from an inhomogeneous membrane thickness, redeposition, or ion channeling.

Thermally sprayed (TS) coatings are widely used for surface engineering across a range of industries, including aerospace, infrastructure and biomedical. TS materials are formed via the successive impingement, rapid quenching and build-up of molten powder particles on a substrate. The impacted ‘splats’ are thus the fundamental microstructural constituents of the coatings, and their intrinsic properties, as well as intersplat bonding and morphology, dictate coating behavior. Beyond the obvious practical considerations, from a scientific standpoint, splats represent a fascinating template for study, due to the highly non-equilibrium processing conditions (rapid deceleration from sub-sonic velocities, million-degree/sec cooling rates). In the literature, many studies of isolated splats on substrates have been carried out, but these have focused on overall morphology (disc-shape vs fragmented). Direct observations of microstructure, in particular cross-section, are limited in the specimen preparation stage due to splat size (tens of microns in diameter, 1-2 microns in thickness). However, Focused Ion Beam (FIB) techniques have allowed this problem to be addressed in a robust manner; in this paper we will discuss such approaches to observe Ni5Al splats on stainless steel substrates. Cross-sections through the splat and the substrate were created by recourse to ion milling and the ion beam itself provided good channeling contrast for grain imaging. The typical splat microstructure with sub-micron Ni(Al) columnar grains, a chill zone at the bottom and a lift off area is observed in high detail. In addition, an amorphous aluminum oxide top layer of 100-200 nm is partially present on top of the Ni(Al) columnar grains. At the splat/substrate interface, defects such as micro- and nano-scale pores were characterized for the first time and will be discussed. These observations provide insights into splat and interface formation during the deposition process and may drastically improve our current understanding of Ni5Al splat properties.