An Investigation of Aromatic and Aliphatic Fluorocarbon Polymer Films: Is Control of Film Properties Possible via Pulsed Plasma Polymerization?

摘要

The quest for higher chip speeds is driving the search for low dielectric constant films for use as inter-level dielectrics (ILDs) in the micr-electronics industry. Organic polymeric materials are desirable for use as is because of iheir inherently low dielectric properties.1 The major drawback to polymeric thin films, however, is their low thermal stability. A key differentiating factor for thermal stability iii these materials is whether the chemical bonds that hold the material together we aromatic or aliphatic. Although plasma deposited fluorocarbon films are expected to have properties similar to bulk polytetrafluoroethylene (PTFE), continuous wave (CW) plasmas produce films with a high degree of crosslinking and F/C ratios ?2.0. Pulsed rf plasmas have recently been used to produce less crosslinked materials with specific surface properties.2'314'5 Results from our pulsed studies using C2F6/H2 plasmas indicate we can deposit less crosslinked fluorocarbon polymer films with high contact angles and CF2 fractions comparable to bulk PTFE.6 Recent studies of fluori'nated poly(arylene ether) films show these materials have a low dielectric constant, thermal stability, and low moisture absorption.1 This has motivated us to explore the use of pulsed plasmas to deposit fluorinated aromatic polymers. Deposition of films with high CF2 content or aromatic components will be important for technological applications of these materials. Recent results from pulsed plasma studies in our laboratory using both aliphatic and aromatic fluorinated monomers to deposit fluorocarbon polymers with specific properties are presented. Deposition parameters and chemical and physical properties of the deposited films will be discussed.