Susan Telford

Uniform tungsten silicide films produced by chemical vapor depostiton

A tungsten silicide film is deposited from WF6 and SiCl2 H2 onto a substrate so that the tungsten to silicon ratio is substantially uniform through the thickness of the WSix film, and the WSix film is substantially free of fluorine. The film can be deposited by a multi-stage process where the pressure in the chamber is varied, or by a high temperature, high pressure deposition process in a plasma cleaned deposition chamber. Preferably the SiCl2 H2 and the WF6 are mixed upstream of the deposition chamber. A seeding gas can be added to the process gases.

Formation of compositionally uniform tungsten silicide films using dichlorosilane in a single‐wafer reactor

High quality chemical vapor deposited (CVD) WSix (2.2<x<2.6) films were deposited on 200 mm Si wafers using SiH2Cl2/WF6 chemistry. Earlier reported problems regarding silicide nucleation at the substrate interface were solved resulting in a highly uniform composition (vertically and laterally) regardless of the substrate type (SiO2 or polycrystalline Si). As‐deposited resistivities of ∼750 μΩ cm were obtained for WSix (x=2.4–2.5) films grown at 550–600 °C. The films were completely crystalline, consisting predominantly of the hexagonal WSi2 phase. The as‐deposited stress in the films was ∼1.3×1010 dyne/cm2 and after 900 °C anneal has reduced to ∼8×109 dyne/cm2. The films contained relatively low levels of impurities: F∼6×1016–2×1017 atoms/cm3, and Cl∼5×1017–5×1018 atoms/cm3.