Method of fabricating a trench structure substantially filled with high-conductivity material

The present invention relates in general to semiconductor devices and processing, and in particular to trench structures used in, for example, trench metal-oxide-semiconductor field effect transistors (MOSFETs), and methods of their manufacture. A trench structure that is substantially filled with high-conductivity material such as refractory metal particularly suitable for fast switching trench MOSFET applications. The trench is first lined by a dielectric material such as silicon dioxide. A layer of polysilicon is then formed on the dielectric material and provides buffering for stress relief. The trench is then filled substantially with refractory metal such as tungsten.