A suitable inert gas such as argon or a mixture of inert and reactive gases such as argon and hydrogen is introduced onto the backside of wafers being processed in a CVD reactor during the deposition of tungsten or other metals, metal nitrides and silicides, to avoid deposition of material on the backside...http://www.google.de/patents/US5230741?utm_source=gb-gplus-sharePatent US5230741 - Gas-based backside protection during substrate processing
