We report an experimental investigation on employing Ag nanoparticles to provide electrical and mechanical contacts between transfer-printed semiconductor devices in the shape of micro/nano- wires and pillars. The Ag nanoparticles have diameters ranging between 200-800nm and are assembled on a 200nm Au film deposited on glass substrates. With a customized tool, an ensemble of silicon pillars were brought into contact with the silver (Ag) nanoparticles (AgNPs) by precisely controlling the displacement and applied force (pressure). Current-voltage measurements were done at force resolution of ~0.2N. The test method aims to illuminate the pillar-particle contact mechanism using the nanoparticles as conductive fillers for the next generation of high performance heteroepitaxial device transfer-printing applications.

In this work we have studied the importance of thermal effects on the structural and transport properties of Ag atomic-size nanowires (NWs) generated by mechanical stretching. Our study involve time-resolved atomic high resolution transmission electron microscopy imaging and quantum conductance measurement using an ultra-high-vacuum mechanically controllable break junction combined with quantum transport calculations. We have observed drastic changes in conductance and structural properties of Ag NWs generated at different temperatures (150 and 300 K). By combining electron microscopy images, electronic transport measurements and theoretical modeling, we have been able to establish a consistent correlation between the conductance and structural properties of Ag NWs. In particular, our study has revealed the formation of metastable rectangular rod-like Ag wires along the [001] crystallographic direction.

We describe an experiment to interface and characterize silver nanoparticle (AgNPs) aggregates that are self-assembled and plastically deformable on a thin gold (Au) film deposited on glass substrate. The electrical characterization is done using an electrical nanoprobe attached to a nano-manipulator inside a scanning electron microscope (SEM). Electrical current-voltage (I-V) measurements are made between the electrical nanoprobe in contact with the nanoparticle and the Au film. The Ag nanoparticles have diameters ranging between ~200-800nm and are self-assembled on a thiolated 100nm Au film. Application of a contact force via the nanoprobe even after substantial particle deformation reveals initially a small non-linear current. Upon current annealing through Joule heating, significant improvement in the electrical contact at the AgNP/substrate interface was observed. This is most likely based on bonding of the AgNPs to the Au film after passage of a high current. The need for such an annealing/sintering step will be critical in forming good ohmic contacts at ambient conditions during transfer printing of semiconductor micro/nanopillars.

Level set methods have been used for Solid phase epitaxial regrowth, etching and deposition.This study is to model the growth of nickel silicide accurately using the level set method. NiSi growth has been observed to follow a linear-parabolic law which takes into account both diffusion and interfacial reaction. This linear-parabolic system is very similar to the Deal and Grove model of SiO2 growth. This model uses similar diffusion transport and reaction rate equations. This simulation models the growth of silicide coupling diffusion solutions to level-set techniques. Dual level sets have been used for top and bottom interface propagation of silicide; velocities were estimated based on nickel concentrations at both interfaces as well as diffusivity and reaction rate of nickel. This is important to predict precise shape of silicide that will allow current crowding and field focusing effects to be modeled in transport out of the intrinsic device into the contacting layers. These simulation models can be used for latest technology nodes at 45, 32, 22nm and special devices such as FinFET’s etc. The level set method is successfully implemented and verified in Florida Object Oriented Process Simulator and growth shapes matches well with the literature Transmission Electron Microscopy data.