Apparatus and method for preventing the premature mixture of reactant gases in CVD and PECVD reactions

An apparatus for depositing a film on a substrate by chemical vapor deposition comprising:

• a reaction chamber with a processing space therein for receiving a substrate;
• a gas delivery system for delivering first and second reactant gases to the processing space for producing a chemical reaction in the processing space and yielding a deposited material film on a substrate therein;
• a generally planar showerhead having a face surface and coupled to said gas delivery system for dispersing the reactant gases into the processing space, the showerhead having a first space therein operable for receiving and dispersing a first reactant gas, and having a second space therein, generally isolated from the first space, and operable for receiving and dispersing a second reactant gas separate from the first gas dispersion for maintaining segregation of reactant gases and generally preventing the premature mixture of the gases prior to their introduction into the processing space;
• the second space comprising a generally cylindrical, planar space, the planar second space symmetry axis being generally coaxial with the axis of symmetry of the showerhead and having an axis of symmetry which is generally perpendicular to the generally planar showerhead, the planar second space further being open over a majority of the showerhead face surface for distributing a second reactant gas over a majority of the face surface, gas-dispersing passages each communicating between the planar second space and the showerhead face surface;
• the first space comprising a plurality of elongated gas distribution passages extending through the showerhead from a peripheral area and coupling to said peripheral area for receiving a first reactant gas, the passages being generally horizontally co-planar and extending generally side-by-side with adjacent passages along significant portions of their length, gas-dispersing passages each communicating between the elongated passages and the showerhead face surface;
• the first and second spaces operable for dispensing the reactant gases over generally the entire face surface of the showerhead for uniform distribution of the reactant gases proximate a substrate;
• whereby the deposition of film material prior to entry of reactant gas into the processing space is reduced.