Stanley Zirinsky

1 µm MOSFET VLSI technology: Part VII—Metal silicide interconnection technology—A future perspective

A major limitation of polycrystalline silicon as a gate material for VLSI applications is its limited conductivity which restricts its usefulness as an interconnection level. An alternative approach which combines a doped polycrystalline silicon layer with a high-conductivity metal silicide such as WSi2(polycide) is described. Such polycide layers are demonstrated to provide at least an order of magnitude improvement in interconnection resistance relative to polycrystalline silicon while maintaining the reliability of the polycrystalline silicon gate and the ability to form passivating oxide layers under typical polycrystalline silicon processing conditions.

Chemical vapor deposition of AlxOyNz films

A chemical vapor deposition process for depositing dielectric films of aluminum oxynitride is described. AlCl3, CO2 and NH3 were employed as the reactive gases in a nitrogen carrier. Films were grown from the mixed gases at 770 and 900°C in a resistively heated fused silica enclosure. The composition of the films could be varied over the entire range of the pseudobinary AlN-Al2O3 system by controlling the NH3/CO2 gas ratio with an appropriate flow of gaseous AlCl3. Growth rate and index of refraction for the films were obtained using ellipsometric techniques. The film compositions reported were determined by electron microprobe analysis. Film structure, evaluated using transmission electron microscopy, and the electrical properties of the dielectric films have been correlated and are discussed separately in a companion paper entitled, “Some Properties of CVD Films of AlxOyNz on Silicon”.