Method of forming suspended gate, chemically sensitive field-effect transistor

A method of forming a chemically sensitive field-effect transistor having a suspended gate comprising:

• forming in a p-type silicon substrate two spaced-apart diffusion regions of n-type doping polarity;
• connecting an external electrical contact to each of said diffusion regions;
• depositing an electrically insulating layer on the substrate and overlying said electrical contacts and the area between them;
• depositing a fugitive layer containing a material selected from the group consisting of aluminum and silicon on the electrically insulating layer overlying at least the area between said diffusion regions;
• forming a thin film on the fugitive layer overlying at least the area between said diffusion regions, said thin film containing at least one element selected from the group consisting of refractory and transition metals;
• depositing a noble metal gate material on the thin-film overlying at least the area between said diffusion regions;
• removing the fugitive layer from the area between said diffusion regions;
• and
• etching with a buffered solution containing a complexing agent for metal ions and metal oxoanions to remove any residual portion of the thin film remaining between said diffusion regions after removal of the fugitive layer to form a suspended gate field-effect transistor having noble metal gate material substantially free of said thin film.