Dissolution behaviors and applications of silicon oxides and nitrides in transient electronics

Silicon oxides and nitrides are key materials for dielectrics and encapsulation layers in a class of silicon-based high performance electronics that has ability to completely dissolve in a controlled fashion with programmable rates, when submerged in bio-fluids and/or relevant solutions. This type of technology, referred to as "transient electronics", has potential applications in biomedical implants, environmental sensors, and other envisioned areas. The results presented here provide comprehensive studies of transient behaviors of thin films of silicon oxides and nitrides in diverse aqueous solutions at different pH scales and temperatures. The kinetics of hydrolysis of these materials depends not only on pH levels/ion concentrations of solutions and temperatures, but also on the morphology and chemistry of the films, as determined by the deposition methods and conditions. Encapsulation strategies with a combination of layers demonstrate enhancement of the lifetime of transient electronic devices, by reducing water/vapor permeation through the defects. Studies of the kinetics of hydrolysis of thin films of silicon oxides and nitrides and the use of these materials as encapsulants are presented for applications in water soluble, transient electronic devices. Dissolution rates of various oxides and nitrides depend on the pH and ionic concentration, the temperature of the solution, and the film properties. Encapsulation with these materials prevents water permeation for up to 10 days.