A simple model for the deposition of W-O coatings by reactive gas pulsing process

¹ SEG-CEMUC – Department of Mechanical Engineering, University of Coimbra, 3030-788 Coimbra, Portugal
² Department of Control Engineering, Faculty of Electrical Engineering, Czech Technical University in Prague, Technická 2, Prague 166 27, Czech Republic
³ NV Bekaert SA, Bekaertstraat 2, 8550 Zwevegem, Belgium

Corresponding author: albano.cavaleiro@dem.uc.pt

Received: 20 November 2007
Revised: 6 February 2008
Accepted: 3 March 2008
Published online: 30 April 2008

Abstract

In this study we will present a simple semi-empirical method to predict the chemical composition and the deposition rate of tungsten oxide coatings deposited by magnetron sputtering with reactive gas pulsing process (RGPP) as a function of two easily measured deposition parameters: target potential and total pressure. The coatings were deposited by DC magnetron sputtering from a pure tungsten target in reactive atmosphere (Ar + O₂) using the conventional process (CP) with constant oxygen flow and the RGPP. The oxygen flow was varied from 0 (pure tungsten deposition) to 20 sccm corresponding to tungsten trioxide during the conventional process. When RGPP was used, a 20 sccm oxygen flow was pulsed using a square regulation signal, defined by a pulsing period (T) and an oxygen injection time (t_ON). The conventional and RGPP process parameters (target potential, total pressure and deposition rate) and the corresponding chemical composition were used to build a simple model predicting the deposition rate and the average chemical composition of the coatings deposited by RGPP as a function of the pulsing parameters. It was shown that the measured total pressure could be used to calculate the deposition rate and the chemical composition of the RGPP coatings with reasonable precision.