Apparatus for providing uniform gas delivery to a reactor

An apparatus, comprising

• a reactor chamber;
• gas source arrays disposed within the reactor chamber, the gas source arrays having:
• (i) a first gas source orifice array disposed a first distance from a surface of a work-piece within the reactor chamber along an axis defined by gas flow towards the surface of the work-piece, and
• (ii) a second gas source orifice array separate from and not fluidly coupled to the first gas source orifice array, the second gas source orifice array disposed at a second distance from the surface of a work-piece along the axis defined by gas flow towards the surface of the work-piece, said second distance being less than said first distance;
• and
• vacuum means coupled to evacuate gasses from the reactor chamber,
• wherein, the first and second gas source orifice arrays are fluidly coupled to:
• (i) flow, during a first time interval, a purge gas into the reactor chamber from the first gas source orifice array while flowing a first reactive precursor into the reactor chamber from the second gas source orifice array;
• (ii) flow, during a second time interval, the purge gas into the reactor chamber from both the first and second gas source orifice arrays while evacuating the reactor chamber;
• (iii) flow, during a third time interval, a second reactive precursor into the reactor chamber from the first gas source orifice array while flowing the purge gas into the reactor chamber from the second gas source orifice array;
• and
• (iv) flow, during a fourth time interval, the purge gas into the reactor chamber from both the first and second gas source orifice array While evacuating the reactor.