Chemical control features in wafer process equipment

A method of delivering one or more fluids into a semiconductor processing chamber, comprising:

• flowing a first fluid through a gas distribution assembly having a first plate and a second plate, wherein the second plate is positioned axially below the first plate;
• flowing a second fluid through the second plate;
• and
• forming a mixture of the first fluid and the second fluid in a semiconductor processing region of the semiconductor processing chamber, wherein the semiconductor processing region is defined at least in part by a lower surface of the second plate;
• wherein:
• the first plate has a disk shape and a plurality of first apertures formed therethrough, wherein the plurality of first apertures extend beyond a lower surface of the first plate thereby forming a plurality of cylindrical bodies;
• the second plate has a disk shape and is positioned axially below the first plate, the second plate comprises:
• a plurality of second apertures formed in a first region of the second plate and through the second plate, wherein the plurality of second apertures align with the plurality of first apertures;
• and
• a plurality of third apertures formed in a second region of the second plate and through the second plate, wherein an area defined by the second region is less than an area defined by the first region;
• and
• wherein the second plate is sealingly coupled with the first plate to define a volume between the first plate and the second plate, wherein the volume is fluidly accessible from the plurality of third apertures, and wherein the volume is fluidly isolated from the plurality of first apertures and the plurality of second apertures.

A semiconductor processing chamber, comprising:

• a gas distribution assembly having a first plate and a second plate, wherein:
• the first plate has a disk shape and a plurality of first apertures formed therethrough, wherein the plurality of first apertures extend beyond a lower surface of the first plate thereby forming a plurality of cylindrical bodies;
• the second plate has a disk shape and is positioned axially below the first plate, the second plate comprises:
• a plurality of second apertures formed in a first region of the second plate and through the second plate, wherein the plurality of second apertures align with the plurality of first apertures;
• and
• a plurality of third apertures formed in a second region of the second plate and through the second plate, wherein an area defined by the second region is less than an area defined by the first region;
• and
• wherein the second plate is sealingly coupled with the first plate to define a volume between the first plate and the second plate, wherein the volume is fluidly accessible from the plurality of third apertures, and wherein the volume is fluidly isolated from the plurality of first apertures and the plurality of second apertures.