| AVS 54th International Symposium | |
| Surface Science | Tuesday Sessions |
| Session SS-TuP |
| Session: | Surface Science Poster Session |
| Presenter: | A. Biswas, University of Alaska, Fairbanks |
| Authors: | A. Biswas, University of Alaska, Fairbanks I.S. Bayer, University of Alaska, Fairbanks P.C. Karulkar, University of Alaska, Fairbanks |
| Correspondent: | Click to Email |
Embedding capacitors has become a critical system need for high performance miniaturized electronic systems. Fabrication and performance constraints make developing materials, processes, structures, and devices for embedded capacitor technology a great challenge. Nanocomposites comprising metal or ceramic nanoparticles in polymer have recently emerged as promising candidates. They offer potential for attaining high capacitance value, high frequency performance, process compatibility, and reliability, while being lightweight, volume-efficient, flexible and low-cost. Among other materials, barium titanate is considered one of the most promising dielectric materials due to its high dielectric constant to blend with polymers to develop high-value capacitors. However, the existing techniques that are mostly based on chemical synthesis and high temperature (>1000°C) sintering followed by blending with the polymers. This makes implementation difficult. In this paper, we present a single-step method based on electron-beam assisted vapor-phase codeposition in vacuum that allows ambient temperature fabrication of nanocomposites (~0.5 µm thick) comprising ferroelectric barium titanate nanoparticles in polymer (polymethyl methacrylate and polyurethane/polyaniline block copolymer) as well as inorganic matrices (LiF). Ferroelectric properties of barium titanate can be achieved without post deposition annealing. Preliminary capacitance-frequency results exhibit flat capacitance densities around 12-15 nF/cm2 in most of the devices with a low tangent loss (~ 0.03) and leakage current of about 70 nA/cm2 in the -20 V to +20 V bias region over a frequency region of 10-100 MHz. Exposing the capacitors to prolonged heating at 125°C for several days to investigate the effects of thermal stress on the device capacitance resulted in a slight reduction in the capacitance density which may be due to the possible transition from ferroelectric to paraelectric phase in barium titanate. However, overall high-frequency response improved significantly due to minimized ferroelectric loss that resulted in self-resonance frequencies occurring beyond 250 MHz. The paper will describe the novel application of vacuum codeposition technique, very encouraging physical and electrical characterization results, and their potential for embedded technology.1
1Financial support of the Defense Microelectronics Activity is acknowledged.