Date of Award

5-2017

Document Type

Thesis

Degree Name

Master of Science (MS)

Legacy Department

Electrical Engineering

Committee Member

Dr. William R. Harrell, Committee Chair

Committee Member

Dr. Yuri Freeman

Committee Member

Dr. Goutam Koley

Abstract

Polymer Hermetic Sealed (PHS) capacitors are advanced polymer capacitors with a hermetic seal enclosing the materials inside a metal enclosure. Their primary features include leakage current stability, high volumetric efficiency, and low weight compared to both wet and solid-state polymer tantalum capacitors. However, Life Tests performed on these capacitors have revealed a failure to withstand their rated voltage in a working temperature range over the long-term. There are also other interesting properties which have been observed such as Breakdown voltage (BDV) exceeding the Formation Voltage (Vf), anomalous transient currents, and a larger than expected capacitance dependence on temperature, C(T). A primary goal in this research is to understand whether the observed characteristics of PHS capacitors are a result of their complex structure or due more to the nature of interactions between the organic and inorganic material layers present. C(T) and BDV measurements were performed on thin-film MIS capacitors representing the material layers of PHS capacitors. Measurements were performed in the voltage range (0V-100V), a temperature range (-550C to 1250C), with varying frequency (20-10kHz), under both humid and dry conditions. Furthermore, one sample went through a curing process referred to as "Heat Treatment", which is thought to improve device stability. Results from these measurements show that thin-film devices can be reasonable representatives of discrete PHS capacitors, and the properties observed in PHS capacitors are significantly dependent on the material layers in the capacitors. Thus, the thin-film MIS capacitor is shown to be a useful test structures for investigating physical phenomena observed in the more complex polymer Ta capacitor structure.

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