Inkjet printed gold nanoparticle films for microelectromechanical systems

The field of microelectromechanical systems (MEMS) was born out of the integrated circuit (IC) industry by adapting semiconductor materials and their associated processing techniques to realize sensors and actuators which rely, in part, upon the mechanical characteristics of materials originally developed for their electrical properties. Unfortunately, semiconductor fabrication facilities can also act as a hindrance for MEMS development, as the per-unit cost of the methods and materials used are extremely high for small production volumes. Just as the original MEMS researchers found inspiration in the IC industry, one only needs to look at recent advances in printed electronics for potential opportunities in MEMS. Inkjet printing, due to its selective nature, represents one form of additive manufacturing with potential to enable microsystems manufacturing. The realization of microelectromechanical systems using additive inkjet printing requires a fundamentally different approach when compared to conventional subtractive microfabrication techniques.;One promising precursor ink for the development of gold microsystems consists of hexanethiol-encapsulated gold nanoparticles (Au-NP) suspended in α-terpineol. This Au-NP ink requires post-deposition thermal steps which drive off the organic encapsulant material, and subsequently sinters the nanoparticles into a coherent conductive gold film. This dissertation develops the techniques and processes required to fabricate sintered inkjet printed gold films suitable for microelectromechanical systems.;A custom inkjet deposition system has been realized for the controlled patterning of Au-NP ink. The electrical and mechanical characteristics of printed gold films under varied sintering conditions are measured in order to gain insight to the appropriate sintering and deposition conditions necessary for printed microsystems. To enable multilayer devices, an aerosol deposited dielectric is studied for use in printed MEMS applications. Sintered gold films can exhibit process-dependent properties as shown by measurements of the temperature coefficient of resistance (TCR) for different printed films. A prototype jet-deposited gold microfabrication process is presented and demonstrated through the development of printed gold passive RF devices, demonstrating the viability of inkjet printed hexanethiol-encapsulated gold nanoparticle ink as a candidate precursor for gold microelectromechanical systems.