Abstract
Thermally stable materials with low dielectric constant (k<3.9) are being hotly pursued. They are essential as interlayer dielectrics/intermetal dielectrics in integrated circuit technology, which reduces parasitic capacitance and decreases the RC time constant. Most of the currently employed materials are based on silicon. Low k films based on organic polymers are supposed to be a viable alternative as they are easily processable and can be synthesized with simpler techniques. It is known that the employment of ac/rf plasma polymerization yields good quality organic thin films, which are homogenous, pinhole free and thermally stable. These polymer thin films are potential candidates for fabricating Schottky devices, storage batteries, LEDs, sensors, super capacitors and for EMI shielding. Recently, great efforts have been made in finding alternative methods to prepare low dielectric constant thin films in place of silicon-based materials. Polyaniline thin films were prepared by employing an rf plasma polymerization technique. Capacitance, dielectric loss, dielectric constant and ac conductivity were evaluated in the frequency range 100 Hz–1 MHz. Capacitance and dielectric loss decrease with increase of frequency and increase with increase of temperature. This type of behaviour was found to be in good agreement with an existing model. The ac conductivity was calculated from the observed dielectric constant and is explained based on the Austin–Mott model for hopping conduction. These films exhibit low dielectric constant values, which are stable over a wide range of frequencies and are probable candidates for low k applications.
Highlights
Experimental techniquesThe experimental set-up for the preparation of rf plasma-polymerized aniline is shown in figure 1
RF Source by various researchers [10]
This study is a sequel to the ongoing investigations on polyaniline thin films using ac and rf plasma polymerization techniques
Summary
The experimental set-up for the preparation of rf plasma-polymerized aniline is shown in figure 1. The thickness of the film was measured by a homemade set-up employing Tolansky’s interferometric method [13] In this method, the film whose thickness is to be determined, is deposited on an ultrasonically cleaned glass substrate. The film whose thickness is to be determined, is deposited on an ultrasonically cleaned glass substrate This film, a metal film is evaporated to form a sharp step on the film edge. From the measured values of dielectric constant, dielectric loss and frequency the ac conductivity was calculated using the empirical relation σac = 2πε0εr tan δ. All these measurements were made under dynamic vacuum
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