Fabrication and Microscopic and Spectroscopic Characterization of Planar, Bimetallic, Micro- and Nanopatterned Surfaces

Abstract

Micropatterns and nanopatterns of gold embedded in silver and titanium embedded in gold have been prepared by combining either photolithography or electron-beam lithography with a glue-free template-stripping procedure. The obtained patterned surfaces have been topographically characterized using atomic force microscopy and scanning electron microscopy, showing a very low root-mean-square roughness (<0.5 nm), high coplanarity between the two metals (maximum height difference ≈ 2 nm), and topographical continuity at the bimetallic interface. Spectroscopic characterization using X-ray photoelectron spectroscopy (XPS), time-of-flight secondary-ion mass spectrometry (ToF-SIMS), and Auger electron spectroscopy (AES) has shown a sharp chemical contrast between the two metals at the interface for titanium patterns embedded in gold, whereas diffusion of silver into gold was observed for gold patterns embedded in silver. Surface flatness combined with a high chemical contrast makes the obtained surfaces suitable for applications involving functionalization with molecules by orthogonal adsorption chemistries or for instrumental calibration. The latter possibility has been tested by determining the image sharpness and the analyzed area on circular patterns of different sizes for each of the spectroscopic techniques applied for characterization.This is the first study in which the analyzed area has been determined using XPS and AES on a flat surface, and the first example of a method for determining the analyzed area using ToF-SIMS.

Model Protective Films on Cu-Zn Alloys Simulating the Inner Surfaces of Historical Brass Wind Instruments by EIS and XPS

“…The XPS spectra were collected using a 400 µm monochromatic beam (AlKα source 1486.6 eV) operated at 4.7 mA and 15 kV (70 W). The analyzed area is estimated to be 0.5 mm 2 (Passiu et al, 2017). The average emission angle is 53 • while the angle between the source and the analyser axis is 67.38 • .…”

Measuring the Thickness of Metal Films: A Selection Guide to the Most Suitable Technique

“…If the different layers have a contrast between them, they also have different grey values; the delimitation between one layer and another can be defined as the point where the value is intermediate between the two layers or, more rigorously, at the inflection points of the graph. In this case, the spatial resolution, and therefore the uncertainty of the measurement, is defined as the distance between the points where the variation of the grey value is in the range of 20%-80% [73], as required by ISO 18516 [74]. On the other hand, an incorrect method used to make the separation of the layers more defined is digital post-processing of the images via acting on brightness and contrast.…”

Summary of ISO/TC 201 International Standard ISO 18516:2019 Surface chemical analysis—Determination of lateral resolution and sharpness in beam‐based methods with a range from nanometres to micrometres and its implementation for imaging laboratory X‐ray photoelectron spectrometers (XPS)

“…Recently, a test sample made by using an innovative technology 22 and displaying a layout (see Figure 1) inspired by the pattern on BAM L200 was developed by colleagues at ETH Zurich, Switzerland. 22,23 The Ti pattern in Au is planar on the deep nanometre scale. Edge effects will be negligible for XPS instruments.…”