Gas distribution apparatuses for improving mixing uniformity
Gas distribution apparatuses described herein include a mixing plate adjacent a back plate of a showerhead. The mixing plate has a back surface and a front surface defining a thickness of the mixing plate. The mixing plate has a mixing channel comprising a top portion and a bottom portion defining a mixing channel length and at least two gas inlets in fluid communication with the top portion of the mixing channel. The gas distribution apparatus also includes a mixer disposed within the thickness of the mixing plate in the top portion of the mixing channel. The mixer has a top plate and a mixer stem extending from the top plate and a plurality of blades positioned along the mixer stem length. Also provided are processing chambers including the gas distribution apparatuses described herein.
1 . A gas distribution apparatus comprising:
a mixing plate adjacent a back plate of a showerhead, the mixing plate having a back surface and a front surface defining a thickness of the mixing plate, the mixing plate having a mixing channel comprising a top portion and a bottom portion defining a mixing channel length, the top portion having a first inner diameter and the bottom portion having a second inner diameter not equal to the first inner diameter, the mixing plate including at least two gas inlets in fluid communication with the top portion of the mixing channel; and
a mixer disposed within the thickness of the mixing plate in the top portion of the mixing channel, the mixer having a top plate and a mixer stem extending from the top plate, the mixer stem comprising a top and a bottom defining a mixer stem length, the top of the mixer stem connected to the top plate and extending into the top portion of the mixing channel, the mixer including a plurality of blades positioned along the mixer stem length, and the top plate including at least one top inlet extending through the thickness of the top plate into the mixing channel.
2 . The gas distribution apparatus of claim 1 , wherein there are two gas inlets disposed on the same side of the mixing channel relative to a central axis of the mixing channel.
3 . The gas distribution apparatus of claim 1 , wherein there are two gas inlets arranged at equally spaced angles relative to a central axis of the mixing channel.
4 . The gas distribution apparatus of claim 1 , wherein there are three inlets arranged at equally spaced angles relative to a central axis of the mixing channel to create a swirling flow pattern.
5 . The gas distribution apparatus of claim 1 , wherein each of the at least two gas inlets is configured to flow a different gas.
6 . The gas distribution apparatus of claim 1 , wherein at least one of the two gas inlets is radially aligned with the top portion of the mixing channel.
7 . The gas distribution apparatus of claim 6 , wherein there are three gas inlets and each of the three gas inlets include three inlets that are radially aligned with the top portion of the mixing channel.
8 . The gas distribution apparatus of claim 1 , wherein the first inner diameter is at least 1.5 times greater than the second inner diameter.
9 . The gas distribution apparatus of claim 8 , wherein the first inner diameter is 2 times greater than the second inner diameter.
10 . The gas distribution apparatus of claim 9 , wherein the first inner diameter is in a range of from 20 mm to 40 mm and the second inner diameter is in a range of from 10 mm to 25 mm.
11 . The gas distribution apparatus of claim 1 , wherein there is in a range of from 3 to 6 blades arranged at equally spaced distances along the mixer stem length.
12 . The gas distribution apparatus of claim 1 , wherein a front plate and the back plate of the showerhead are spaced to form a gas volume.
13 . The gas distribution apparatus of claim 12 , wherein the front plate has an inner surface adjacent the gas volume and an outer surface with a plurality of apertures extending therethrough.
14 . The gas distribution apparatus of claim 13 , wherein the gas volume has a center region and an outer region defining a length of the gas volume.
15 . A processing chamber comprising:
a chamber body having a top wall, bottom wall and at least one sidewall defining a processing volume;
a mixing plate adjacent a back plate of a showerhead, the mixing plate having a back surface and a front surface defining a thickness of the mixing plate, the mixing plate having a mixing channel comprising a top portion and a bottom portion defining a mixing channel length, the top portion having a first inner diameter and the bottom portion having a second inner diameter not equal to the first inner diameter, the mixing plate including at least two gas inlets in fluid communication with the top portion of the mixing channel, a mixer disposed within the thickness of the mixing plate in the top portion of the mixing channel, the mixer having a top plate and a mixer stem extending from the top plate, the mixer stem comprising a top and a bottom defining a mixer stem length, the top of the mixer stem connected to the top plate and extending into the top portion of the mixing channel, the mixer including a plurality of blades positioned along the mixer stem length and the top plate including at least one top inlet extending through the thickness of the top plate into the mixing channel; and
a substrate support spaced a distance from a front plate of the showerhead.
16 . The processing chamber of claim 15 , wherein there are two gas inlets disposed on the same side of the mixing channel relative to a central axis of the mixing channel or at equally spaced angles relative to the central axis of the mixing channel.
17 . The processing chamber of claim 15 , wherein there are three inlets arranged at equally spaced angles relative to a central axis of the mixing channel to create a swirling flow pattern.
18 . The processing chamber of claim 15 , wherein at least one of the two gas inlets is radially aligned with the top portion of the mixing channel.
19 . The processing chamber of claim 15 , wherein the front plate and the back plate of the showerhead are spaced to form a gas volume, the front plate has an inner surface adjacent the gas volume and an outer surface has a plurality of apertures extending therethrough, and the gas volume has a center region and an outer region defining a length of the gas volume.