The property of plasma-polymerized fluorocarbon film in relation to CH4/C4F8 ratio and substrate temperature

摘要

This paper shows the systematic study on the property of plasma-polymerized fluorocarbon (PPFC) film formed by a capacitive coupling-type plasma polymerization equipment using a mixture of CH4/C4F8 gas. The thermal stability of PPFC film was improved with substrate temperature. CH4 gas was supplied with C4F8 gas in order to increase the deposition rate. The deposition rate of a few nanometers per minute was obtained at substrate temperature of 200 degrees C by the addition of 20% CH, gas. The PPFC film showed residual thickness of 80% and water contact angle of 110 degrees even after 20 min annealing at 350 degrees C in air. The electrical breakdown strength of the film was measured as 0.7-1.3 MV/cm using mercury probe. The PPFC film was effective to prevent ''in-use stiction'', whose effect was confirmed by a touching test using the electrostatic force for an SOI accelerometer. As another interesting phenomenon, ultra hydrophobic surface (its water contact angle was over 150 degrees) was obtained using the "powder-like" PPFC film, and it was explained by a fractal theory. (C) 2000 Elsevier Science S.A. All rights reserved. [References: 20]