Michael J. Campin

Targeted Ion Milling of Ex Situ Lift-Out FIB Specimens

The semiconductor industry is constantly investigating new methods that can improve both the quality of TEM lamella and the speed at which they can be created. To improve throughput, a combination of FIB-based preparation and ex situ lift-out (EXLO) techniques have been used. Unfortunately, the carbon support on the EXLO grid presents problems if the lamella needs to be thinned once it is on the grid. In this paper, we present low-energy (<1 keV), narrow-beam (<1 μm diameter), Ar ion milling as a method of preparing electrontransparent and gallium-free EXLO FIB specimens.

Sample preparation for aberration-corrected microscopy of high-quality TEM specimens of advanced integrated circuits

Advanced integrated circuits (ICs) are complex due to the fin field effect transistors (FinFETs), which comprise multigate transistors with the source/drain (S/D) channels (fins) surrounded by a threedimensional gate. State-of-the-art ICs are at the 10 nm and 7 nm nodes, with the later at the ramping stage of production[1]. At the 10 nm node, the S/D fins are 25% taller and 25% more closely spaced than 14 nm node technology [2]. Transmission electron microscopy (TEM) is a critical characterization tool for the semiconductor industry given the decreasing device size. Ga focused ion beam (FIB) is frequently used for advanced IC TEM specimen preparation due to its rapid, site-specific sample preparation capabilities. However, FIB milling typically results in specimen artifacts, such as surface amorphization and Ga implanted layers, both of which may limit analytical and high-resolution electron microscopy. Furthermore, 20 nm or less specimen thickness is required to characterize the 3D structures of the FinFET gate oxide in the TEM [3]. In this work, we present targeted, small spot (< 1μm ), low energy Ar milling for reproducible specimen preparation of advanced ICs with specimen thicknesses of less than 20 nm that removes FIB-induced artifacts.

Accurate Removal of Implanted Gallium and Amorphous Damage from TEM Specimens after Focused Ion Beam (FIB) Preparation

One of the most popular tools for TEM specimen preparation is gallium focused ion beam (FIB). It is well known that the FIB’s high-energy Ga ions can damage a specimen’s crystalline structure by introducing lattice defects (strain induction). FIB milling can also implant gallium ions into the specimen surface and cause surface amorphization [1]. An accurate and reproducible specimen preparation method that removes gallium and amorphous damage after FIB processing is necessary for TEM analysis. This work demonstrates how the quality of TEM specimens after FIB can be improved by using low energy argon ion milling.

Narrow-Beam Argon Ion Milling of Carbon-Supported Ex Situ Lift-Out FIB Specimens

Focused ion beam (FIB) tools are used to prepare transmission electron microscopy (TEM) specimens due to the site specificity and accuracy of specimen thinning and extraction that it provides [1, 2]. The preparation of TEM specimens using gallium-based FIB tools with in situ lift-out capability has been the standard for characterization and failure analysis of materials and devices in the semiconductor industry for many years [3]. To further improve throughput in the semiconductor manufacturing industry, an inline TEM sample preparation method with ex situ lift-out (EXLO) technique on a perforated, carbon supported, mesh-type TEM grid was introduced [3, 4]. Unfortunately, the carbon support presents problems if the lamella needs to be thinned for high-resolution TEM analysis or if one is attempting to precisely determine the region of interest on the device. Further thinning of the specimen on a carbon support is limited due to preferential milling of the carbon support, which could result in loss of the specimen. In this work, we introduce the feasibility of using the narrow-beam argon ion milling capabilities of the PicoMill TEM specimen preparation system [Fischione Instruments] to improve carbon-supported EXLO specimens without compromising the integrity of the support and to end-point on specific features. The result is electron transparent and gallium-free specimens that contain only the features of interest.

EBSD and TEM Microstructural Studies of New Fuel Cladding in Generation IV Sodium-cooled Fast Nuclear Reactors

A proposed design for Generation IV nuclear systems is a sodium-cooled fast reactor (SFR) [1]. The use of liquid sodium as a coolant requires a high-performance fuel cladding material. One candidate is vanadium alloy V4Cr4Ti [2]; however, because of vanadium’s high affinity for oxygen, an oxygen concentration as low as 1 ppm in Na [2] provokes vanadium oxide formation, which results in a failure of the fuel cladding protection. To avoid oxygen embrittlement of fuel rods, a diffusion barrier based on a multilayered silicide coating type SixVy was proposed [3]. The combination of electron backscatter diffraction (EBSD) and high resolution transmission electron microscopy (HRTEM) provide full-scale structural characterization and an understanding of the mechanical properties, degradation mechanisms, and substrate adhesion (in the case of protective coatings) of such functional materials.