Method of selectively depositing tungsten upon a semiconductor substrate

摘要

A method of selectively depositing tungsten upon a silicon semiconductor substrate. A silicon substrate is coated with a masking film of PSG or SiO2 that is patterned to provide an opening for forming an electrode or wiring. On a portion of the substrate in the opening, a layer of tungsten having a thickness of approximately 2000 ANGSTROM is deposited by a CVD method from an atomosphere containing a gaseous mixture of WF6 and H2 . During this processing, tungsten nucleuses deposit on the surface of the masking film as well. Before such nucleuses form a film, the deposition processing is discontinued and H2 gas is fed into the CVD apparatus to produce HF, which etches the surface of the masking film, and thus tungsten nucleuses are removed. The deposition and removal steps are repeated several times until the height of the deposited tungsten and the thickness of the masking film are essentially equal to present a flat surface. Aluminum film is deposited on the flat surface and patterned by lithography. The flat aluminum deposition allows fabrication of accurate and reliable wirings and facilitates production of VLSI of sub-micron order.