Papers by Keyword: Organic Monolayers

Abstract: Typically, copper material is used as a bonding material in MEMs devices for its excellent mechanical, electrical and hermetic properties. Direct copper bonding, however, requires high temperature (>300°C) to forge a bond due to the oxidative nature of copper. In this study, using an alternative approach based on an organic monolayer coating, we demonstrate metallurgical bonding between two copper surfaces under ambient condition at low bonding temperature below 140°C, while maintaining reliable mechanical joint integrity of 50MPa. This monolayer is believed to behave as a passivation layer, protecting the copper surface against oxidation under ambient conditions. In contrast to a bulk oxide layer, this layer can be easily displaced during mechanical deformation at the bonding interface.

Abstract: The electrical properties of structures included 1-octadecene (CnH2n, n=18) monolayers deposed onto the oxide-free silicon surface or Si/SiGe/Si layers were analyzed as a function of surface pretreatment (hydrogen- or iodine-terminated silicon surface) and layer deposition regime (thermal- or photo-activated process). Two types of traps (for electrons and holes) were found at the interface between the monolayers and substrate. The density of traps was shown to depend on the, H- or I-termination of the silicon surface, the illumination intensity and deposition time during photo-activated deposition, and the temperature of thermal-activated deposition. The optimal regimes can be chosen for minimization of the surface charge in the structures covered with 1- octadecene monolayers, which provides a high conductivity of thin near-surface layers.