A Multi-Technique Investigation of the Pulsed Plasma and Plasma Polymers of Acrylic Acid: Millisecond Pulse Regime

Abstract

Acrylic acid plasma polymers have been fabricated from pulsed 13.56 MHz RF plasmas in a “capacitively” coupled plasma deposition chamber. Plasma “on” and “off” (ton/off) times in the millisecond (ms) pulse time regime have been investigated using a peak plasma power of 50 W. Employing a fixed ton (5 ms), the effect of toff (2−1000 ms) on the solid-phase plasma polymer has been investigated using X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF SIMS). For the first time, mass spectrometry has been employed to monitor the neutral and charged species in pulsed plasma (gas-phase) as a function of toff. These measurements are supported by quartz crystal mass balance (QCMB) deposition rate measurements. Throughout the study, comparison with continuous (CW) wave plasmas of equivalent “average” power has been made.XPS analyses revealed that with increased toff (i.e., lower “average” power) the extent of carboxyl retention increased from <33% at a toff of 5 ms to ca. 6...