Deposition chamber and method for depositing low dielectric constant films

One of the primary steps in the fabrication of modem semiconductor devices is the formation of a thin film on a semiconductor substrate by chemical reaction of gases. Such a deposition process is referred to as chemical vapor deposition (CVD). Conventional thermal CVD processes supply reactive gases to the substrate surface where heat-induced chemical reactions can take place to produce the desired film. Plasma CVD processes promote the excitation and/or dissociation of the reactant gases by the application of radio frequency (RF) energy to the reaction zone proximate the substrate surface thereby creating a plasma of highly reactive species. The high reactivity of the released species reduces the energy required for a chemical reaction to take place, and thus lowers the required temperature for such CVD processes. An improved deposition chamber () includes a housing () defining a chamber () which houses a substrate support (). A mixture of oxygen and SiFis delivered through a set of first nozzles () and silane is delivered through a set of second nozzles () into the chamber around the periphery () of the substrate support. Silane (or a mixture of silane and SiF) and oxygen are separately injected into the chamber generally centrally above the substrate from orifices (). The uniform dispersal of the gases coupled with the use of optimal flow rates for each gas results in uniformly low (under 3.4) dielectric constant across the film.