Button shear testing for adhesion measurements of 2D materials

• Published in: Nature communications Vol. 15; no. 1; p. 2430
• Main Authors: Schätz, Josef, Nayi, Navin, Weber, Jonas, Metzke, Christoph, Lukas, Sebastian, Walter, Jürgen, Schaffus, Tim, Streb, Fabian, Reato, Eros, Piacentini, Agata, Grundmann, Annika, Kalisch, Holger, Heuken, Michael, Vescan, Andrei, Pindl, Stephan, Lemme, Max C.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 18.03.2024; Nature Publishing Group; Nature Portfolio
• Subjects: 140/133; 142/126; 147/135; 147/3; 639/166/988; 639/301/357/1018; 639/925/930/12; Adhesion; Adhesive strength; Boron; Boron nitride; Fabrication; Graphene; Humanities and Social Sciences; Molybdenum; Molybdenum disulfide; multidisciplinary; Nanoelectronics; Oxygen plasma; Polymers; Science; Science (multidisciplinary); Shear strength; Shear tests; Silica; Silicon; Silicon dioxide; Silicon nitride; Silicon substrates; Substrates; Thermal resistance; Tungsten; Two dimensional materials
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-024-46136-8

Two-dimensional (2D) materials are considered for numerous applications in microelectronics, although several challenges remain when integrating them into functional devices. Weak adhesion is one of them, caused by their chemical inertness. Quantifying the adhesion of 2D materials on three-dimensional surfaces is, therefore, an essential step toward reliable 2D device integration. To this end, button shear testing is proposed and demonstrated as a method for evaluating the adhesion of 2D materials with the examples of graphene, hexagonal boron nitride (hBN), molybdenum disulfide, and tungsten diselenide on silicon dioxide and silicon nitride substrates. We propose a fabrication process flow for polymer buttons on the 2D materials and establish suitable button dimensions and testing shear speeds. We show with our quantitative data that low substrate roughness and oxygen plasma treatments on the substrates before 2D material transfer result in higher shear strengths. Thermal annealing increases the adhesion of hBN on silicon dioxide and correlates with the thermal interface resistance between these materials. This establishes button shear testing as a reliable and repeatable method for quantifying the adhesion of 2D materials. 2D materials are being investigated for several applications in micro- and nanoelectronics, but their weak adhesion represents a critical challenge for device integration. Here, the authors propose a button shear testing method to evaluate the adhesion forces of various large-area 2D films on SiO 2 and Si 3 N 4 substrates.