Anti-transient showerhead

1. An apparatus comprising:

a first gas inlet;

a first surface, wherein the first gas inlet is configured to deliver a first process gas through the first surface;

a plurality of first gas distribution ports;

a second surface, wherein the plurality of first gas distribution ports are configured to deliver the first process gas through the second surface;

a third surface interposed between the first surface and the second surface;

a fourth surface interposed between the third surface and the second surface; a plurality of first raised bosses that extend up from the second surface towards the fourth surface;

a plurality of first gas flow passages interposed between the first surface and the third surface; and

a plurality of first holes passing through the fourth surface, wherein:

the first surface and the third surface at least partially define a first inlet plenum volume that is fluidically connected with the first gas inlet,

the second surface and the fourth surface at least partially define a first gas distribution plenum volume that is fluidically connected with each first gas distribution port of the plurality of first gas distribution ports,

each first gas flow passage of the plurality of first gas flow passages has a corresponding first end that fluidically connects with the first inlet plenum volume and a corresponding second end that fluidically connects with the first gas distribution plenum volume via a corresponding first hole of the plurality of first holes,

each first raised boss of the plurality of first raised bosses is centered on a corresponding first hole of the plurality of first holes and has a corresponding top surface facing the fourth surface that is offset from the fourth surface by a corresponding first distance, and

each first gas flow passage of the plurality of first gas flow passages is substantially the same length, extends away from the first inlet plenum volume at the corresponding first end, and includes between 140° and 200° of bends between the corresponding first end and the corresponding second end such that the corresponding second end is oriented towards the first inlet plenum volume.

2. The apparatus of claim 1 , wherein

each first raised boss of the plurality of first raised bosses has a corresponding nominal diameter and a corresponding first distance between 1/11 th and 1/13 th of the corresponding nominal diameter.

3. The apparatus of claim 1 , wherein different subsets of first gas distribution ports of the plurality of first gas distribution ports are adjacent to each first raised boss of the plurality of first raised bosses and each first raised boss of the plurality of first raised bosses is centered between the first gas distribution ports of a corresponding subset of the different subsets of the first gas distribution ports of the plurality of first gas distribution ports.

4. The apparatus of claim 1 , further comprising a plurality of first support columns, wherein each first support column of the plurality of first support columns spans between the second surface and the fourth surface.

5. The apparatus of claim 1 , wherein each first hole of the plurality of first holes has a diameter of between 1.5 mm and 3 mm and wherein each first raised boss of the plurality of first raised bosses has a diameter of between 5 mm and 8 mm.

6. The apparatus of claim 1 , further comprising a plurality of first peninsulas, wherein:

the first inlet plenum volume has a first center point,

each first peninsula of the plurality of first peninsulas protrudes into the first inlet plenum volume, and

the corresponding second end of one or more of the first gas flow passages of the plurality of first gas flow passages extends into

a corresponding first peninsula of the plurality of first peninsulas and

is closer to the first center point than the corresponding first end of the corresponding first gas flow passage of the plurality of first gas flow passages.

7. The apparatus of claim 1 , wherein each first gas flow passage of the plurality of first gas flow passages includes between 150° and 190° of bends between the corresponding first end and the corresponding second end.

8. The apparatus of claim 1 , wherein each first gas flow passage of the plurality of first gas flow passages has a length within ±30% of the other first gas flow passages.

9. The apparatus of claim 1 , wherein the cross-sectional area of each first gas flow passage of the plurality of first gas flow passages along the length of the corresponding first gas flow passage of the plurality of first gas flow passages is constant.

10. The apparatus of claim 1 , wherein the corresponding first end of each first gas flow passage of the plurality of first gas flow passages is equidistant from a first axis of the apparatus.

11. The apparatus of claim 1 , wherein there are between 20 and 100 first gas flow passages in the plurality of first gas flow passages.

12. The apparatus of claim 1 , further comprising:

a second gas inlet;

a fifth surface, wherein the second gas inlet is configured to deliver a second process gas through the fifth surface;

a plurality of second gas distribution ports;

a sixth surface, wherein the plurality of second gas distribution ports are configured to deliver the second process gas through the sixth surface;

a seventh surface interposed between the fifth surface and the sixth surface;

an eighth surface interposed between the sixth surface and the seventh surface;

a plurality of second gas flow passages interposed between the fifth surface and the seventh surface; and

a plurality of second holes passing through the eighth surface, wherein:

the fifth surface and the seventh surface at least partially define a second inlet plenum volume that is fluidically connected with the second gas inlet,

the sixth surface and the eighth surface at least partially define a second gas distribution plenum volume that is fluidically connected with each second gas distribution port of the plurality of second gas distribution ports,

each second gas flow passage of the plurality of second gas flow passages has a corresponding first end that fluidically connects with the second inlet plenum volume and a corresponding second end that fluidically connects with the second gas distribution plenum volume via a corresponding second hole of the plurality of second holes, and

each second gas flow passage of the plurality of second gas flow passages is substantially the same length, extends away from the second inlet plenum volume at the corresponding first end, and includes between 140° and 200° of bends between the corresponding first end and the corresponding second end such that the corresponding second end is oriented towards the second inlet plenum volume.

13. The apparatus of claim 12 , wherein:

a plurality of second raised bosses

extends up from the sixth surface towards the eighth surface,

each second raised boss of the plurality of second raised bosses is centered on a corresponding second hole of the plurality of second holes, and

each second raised boss of the plurality of second raised bosses has a corresponding top surface facing the eighth surface that is offset from the eighth surface by a second distance.

14. The apparatus of claim 12 , wherein the first gas inlet includes a plurality of ports and the first inlet plenum volume is partitioned into multiple first inlet plenum sub-volumes, each first inlet plenum sub-volume of the multiple first inlet plenum sub-volumes associated with a different port of the plurality of ports.

15. The apparatus of claim 12 , wherein the first inlet plenum volume, the second inlet plenum volume, the first gas distribution plenum volume, and the second gas distribution plenum volume are arranged in a stacked configuration and in an order selected from the group consisting of:

(i) second inlet plenum volume, first inlet plenum volume, first gas distribution plenum volume, and second gas distribution plenum volume;

(ii) second inlet plenum volume, first inlet plenum volume, second gas distribution plenum volume, and first gas distribution plenum volume;

(iii) second inlet plenum volume, first gas distribution plenum volume, first inlet plenum volume, and second gas distribution plenum volume; (iv) first inlet plenum volume, second inlet plenum volume, first gas distribution plenum volume, and second gas distribution plenum volume; and

(v) first inlet plenum volume, second inlet plenum volume, second gas distribution plenum volume, and first gas distribution plenum volume.

16. The apparatus of claim 13 , wherein different subsets of first gas distribution ports of the plurality of first gas distribution ports are adjacent to each first raised boss of the plurality of the plurality of the first raised bosses and each first raised boss of the plurality of first raised bosses is centered between the first gas distribution ports of a corresponding subset of the different subsets of the first gas distribution ports of the plurality of first gas distribution ports.

17. The apparatus of claim 13 , wherein different subsets of second gas distribution ports of the plurality of second gas distribution ports are adjacent to each second raised boss of the plurality of second raised bosses and each second raised boss of the plurality of second raised bosses is centered between the second gas distribution ports of a corresponding subset of the different subsets of the second gas distribution ports of the plurality of second gas distribution ports.

18. The apparatus of claim 12 , further comprising a plurality of first support columns and a plurality of second support columns, wherein:

each first support column of the plurality of first support columns spans between the second surface and the fourth surface, and

each second support column of the plurality of second support columns spans between the sixth surface and the eighth surface.

19. The apparatus of claim 12 , further comprising a plurality of first peninsulas, wherein:

the first inlet plenum volume has a first center point,

each first peninsula of the plurality of first peninsulas protrudes into the first inlet plenum volume, and

the corresponding second end of one or more of the first gas flow passages of the plurality of first gas flow passages extends into a corresponding first peninsula of the

plurality of first peninsulas and is closer to the first center point than the corresponding first end of the corresponding first gas flow passage of the plurality of first gas flow passages.

20. The apparatus of claim 12 , further comprising a plurality of second peninsulas, wherein:

the second inlet plenum volume has a second center point,

each second peninsula of the plurality of second peninsulas protrudes into the second inlet plenum volume,

the corresponding second end of one or more of the second gas flow passages of the plurality of second gas flow passages extends into a corresponding second peninsula of the plurality of second peninsulas and is closer to the second center point than the corresponding first end of the corresponding second gas flow passage of the plurality of second gas flow passages.

21. The apparatus of claim 1 , wherein each of the corresponding first distances is between 0.025 mm and 1.2 mm for the corresponding first raised boss of the plurality of first raised bosses.

22. The apparatus of claim 1 , wherein:

each first hole has a hole diameter, and

each of the corresponding first distances is less than twice a difference between a nominal boss diameter for the corresponding first raised boss of the plurality of first raised bosses and the corresponding hole diameter and is greater than 0.2 times the difference between the nominal boss diameter for the corresponding first raised boss of the plurality of first raised bosses and the corresponding hole diameter.

23. The apparatus of claim 1 , wherein the first raised bosses of the plurality of first raised bosses each have a nominal diameter of between 5 mm and 8 mm.

24. The apparatus of claim 1 , wherein the length of each first gas flow passage of the plurality of first gas flow passages is within ±5% of the lengths of the other first gas flow passages in the plurality of first gas flow passages.

25. The apparatus of claim 1 , wherein the length of each first gas flow passage of the plurality of first gas flow passages is within ±10% of the lengths of the other first gas flow passages in the plurality of first gas flow passages.

26. The apparatus of claim 1 , wherein the length of each first gas flow passage of the plurality of first gas flow passages is within ±20% of the lengths of the other first gas flow passages in the plurality of first gas flow passages.