With the continuous scaling down of devices towards higher speed and higher density in the semiconductor industry, the resistance of wordline has become a critical limitation of circuit speed. An alternative is deposition of a pure metal on the polysilicon wordline. In this work, we chose CVD tungsten for wordline thin film coating. The problems of typical CVD tungsten film are fluorine penetration into the gate oxide and redistribution of dopant in the polysilicon. This could shift the characteristics of the devices. With the deposition of an amorphous-like tungsten film prior to a CVD tungsten film with typical columnar structure, we could demonstrate that such a bi-layer tungsten film shows much improvement in device performance.
|Number of pages||18|
|Journal||Journal of Wide Bandgap Materials|
|State||Published - 1 Dec 1998|