Alternative FIB TEM Sample Preparation Method for Cross-Sections of Thin Metal Films Deposited on Polymer Substrates

Abstract

Transmission electron microscopy (TEM) and focused ion beam (FIB) are proven tools to produce site-specific samples in which to study devices from initial processing to causes for failure, as well as investigating the quality, defects, interface layers, etc. However, the use of polymer substrates presents new challenges, in the preparation of suitable site-specific TEM samples, which include sample warping, heating, charging, and melting. In addition to current options that address some of these problems such as cryo FIB, we add an alternative method and FIB sample geometry that address these challenges and produce viable samples suitable for TEM elemental analysis. The key feature to this approach is a larger than usual lift-out block into which small viewing windows are thinned. Significant largely unthinned regions of the block are left between and at the base of the thinned windows. These large unthinned regions supply structural support and thermal reservoirs during the thinning process. As proof-of-concept of this sample preparation method, we also present TEM elemental analysis of various thin metallic films deposited on patterned polycarbonate, lacquer, and poly-di-methyl-siloxane substrates where the pattern (from low- to high-aspect ratio) is preserved.

Controlled Incorporation of Silver Nanoparticles into Layer-by-Layer Polymer Films for Reusable Electronic Tongues

“…Two LbL films were prepared with different concentrations of silver nanoparticles incorporated in the PAH/PSS to investigate the depth profile of the silver nanoparticles in the polymer matrix. Using a Dual Beam Helios 660 from the CNPEM, we produced sample cross-section lamellae with the lift-out method 35 that were analyzed using scanning transmission electron microscopy with a high-angle annular darkfield (STEM-HAADF) detector in a JEOL 2100F operated at 200 kV, also from CNPEM.…”

Fabrication of high quality plan-view TEM specimens using the focused ion beam

“…FIB preparation of cross-sectional specimens for TEM is now commonplace [10] and is applicable to almost arbitrary materials, including polymers [11], biomaterials [12] and ceramics [13]. A major advantage is the unrivalled site-specificity offered by dual-beam FIB systems, which simultaneously image a sample with an electron beam whilst using an ion beam (most commonly Ga + ) to cut out a thin, micron-scale lamella from a bulk specimen [14].…”

FIB-Etching of Polymer/Metal Laminates and its Effect on Mechanical Performance

“…The remaining material may be damaged. The effects of ion beam milling on polymeric materials has been studied extensively in recent years, (Kim et al, 2011; Bassim et al, 2012; Rivera et al, 2013).…”

“…This technique was successfully used to prepare crosssections of polymer/metal interfaces (Faber et al, 2014). FIB is not supposed to introduce strain into the material near the interface (Kim et al, 2011;Lee et al, 2011Lee et al, , 2012Bassim et al, 2012;Schmied et al, 2012;Rivera et al, 2013). In FIB a focused beam of 30 keV Ga + ions is used to sputter material.…”