The Adhesion of Mica Nanolayers on a Silicon Substrate in Air

Abstract Mica nanolayers (MNL) are a new dielectric material that can improve the electron transport properties of Si based microelectronic devices. However, the mechanical reliability of such devices is not well understood because measurement of the adhesion between an MNL and a Si substrate is insufficiently accurate. The recent work reports a bridging method that is developed based on the linear beam theory and can characterize the adhesion of MNL on a mica substrate in a reasonably accuracy. In this work, the accuracy of the bridging method is improved by using a nonlinear mechanical model. 15 MNL specimens are measured on a Si substrate in air and the new model gives an average adhesion energy of 119.69 ± 20.47 mJ m^–2. The effect of environment on the adhesion is also investigated. The increase in temperature from 25 to 300 °C enhances adhesion, attributed to the increased bonding effect of interfacial contaminants. When humidity is below a threshold value, 80% in this case, the adhesion energy remains unchanged, but above the threshold, the nanobridges collapse during testing. Molecular dynamics simulation reveal that the collapse is because the increase of interfacial water molecules reduces the frictional force between the MNL and Si substrate.