EVALUATION OF THE SELECTIVE TUNGSTEN DEPOSITION PROCESS FOR VLSI CIRCUIT APPLICATIONS.

Article abstract of DOI:10.1149/1.2095858

Tungsten films have been selectively deposited on oxide-patterned silicon wafers using two successive deposition steps, i. e. , the Si reduction of WF//6 followed by the H//2 reduction of WF//6. The deposition process was performed in a horizontal hot wall LPCVD reactor. In this reactor, the surface of vertical wafers was parallel to the axis of the quartz tube. The thickness of W films obtained for a given deposition time was found to be dependent on the 'history' (or the cleanliness) of the CVD reactor. The thickness uniformity across a wafer and from wafer to wafer was determined as a function of the wafer position in the CVD reactor. The selectivity of the process was evaluated by measuring the W nuclei density on the oxide (PSG) mask as a function of the thickness of W films.