The primary objectives of this proposal are to synthesize and characterize thin films of high resistivity (undoped), and p- and n -doped polycrystalline diamond (PCD) and cubic-boron nitride (c-BN) suitable for the fabrication of high temperature electronic devices, and application/demonstration of these films for the fabrication of high temperature microelectronic devices.
The thin film processing activities is expected to develop a fundamental understanding for synthesizing and in situ doping of diamond and cubic-boron nitride (c-BN) films predictably and reproducibly by ECR (Electron Cyclotron Resonance) plasma enhanced chemical vapor deposition (ECR-PECVD) on semiconducting substrates. This way of processing creates non-equilibrium (activated) conditions in which novel metastable materials like diamond and c-BN can be synthesized at relatively low temperatures and pressures. The influence of different process parameters (e.g. substrate bias, plasma gas composition, substrate temperature, pressure, and plasma density) on the composition, crystal quality, and properties of the PCD and c-BN films will be studied. Special attention will be given to substrate strategy, precursor selection, catalytic activation, and in situ doping, in order to obtain high quality films suitable for device fabrication. The films will be characterized by IR and Raman Spectroscopy, XRD, SEM, TEM, AFM, AES/XPS, SIMS and Electron Diffraction techniques. In addition, electrical properties of the films will be determined by resistivity, carrier concentration, and dielectric measurements.
Both electrical and optical devices based on the PCD , and to the limited extent using c-BN, will be investigated and fabrication techniques will be developed for the production of high-temperature electronic components. In particular, the following two basic circuits are proposed for investigation: (1) a voltage multiplier stack (VMS) which requires the integration of MSM Schottky diodes with MSM interdigitated capacitors, and (2) an optical bridge of four MSM detectors for DC-to-AC conversion and for driving the voltage multiplier stacks. Most of the devices will be fabricated using PCD with a limited scope for fabricating c-BN based devices in the revised program.
