System and method for depositing a gaseous mixture onto a substrate surface using a showerhead apparatus
A gaseous mixture is deposited onto a substrate surface using a showerhead. A first plenum of the showerhead has a plurality of channels fluidicly coupled with an interior of a processing chamber. A second plenum gas flows through a plurality of tubes extending from a second plenum of the showerhead through the channels into the interior of the processing chamber. The diameter of the tubes is smaller than the diameter of the channels such that a first plenum gas flows into the interior of the processing chamber through a space defined between the outer surface of the tubes and the surface of the channels. The length and diameter of the tubes determine the level of distribution and the molar ratio of the first gas and the second gas in the gaseous mixture that is deposited on the surface of the substrate.
1. A system for depositing a gaseous mixture onto a surface of a substrate, comprising:
a housing defining a processing chamber;
a substrate holder disposed within the processing chamber;
a first gas source;
a second gas source;
a first coolant source;
a second coolant source; and
a CVD showerhead disposed over the substrate holder, the CVD showerhead comprising:
a first plenum fluidicly coupled with the first gas source and having a plurality of channels fluidicly coupled with an interior of the processing chamber;
a second plenum fluidicly coupled with the second gas source;
a third plenum fluidicly coupled with the first coolant source and positioned below the first plenum and above an interior of the processing chamber, wherein the first coolant controls the temperature of the first gas in the first plenum;
a fourth plenum fluidicly coupled with the second coolant source and positioned above the second plenum, wherein the second coolant controls the temperature of the second gas in the second plenum; and
a plurality of tubes extending from the second plenum through the channels and into the interior of the processing chamber, wherein the diameter of the tubes is smaller than the diameter of the channels such that the second gas flows into the interior of the processing chamber through the tubes and the first gas flows into the interior of the processing chamber through a space defined between the outer surface of the tubes and the surface of the channels,
wherein the first coolant controls the temperature of the first gas when the first gas enters the interior of the processing chamber.
2. The system recited in claim 1 wherein the diameter of the tubes extending into the interior of the processing chamber determines the molar ratio of the first gas and the second gas in the gaseous mixture that is deposited on the surface of the substrate positioned on the substrate holder.
3. The system recited in claim 1 wherein at least one of the channels has a varying diameter.
4. The system recited in claim 1 wherein the gaseous mixture comprising the first gas and the second gas does not begin forming until the second gas exits the tubes and enters the interior of the processing chamber.
5. The system recited in claim 1 wherein the first gas and the second gas enter the interior of the chamber isolated from each other.