Suppression of parasitic deposition in a substrate processing system by suppressing precursor flow and plasma outside of substrate region

1. A method for operating a substrate processing system, comprising:

delivering precursor gas to a chamber using a showerhead, wherein the showerhead includes a head portion and a stem portion,

wherein the head portion includes an upper surface, a sidewall, a lower planar surface including a plurality of holes, and a cylindrical cavity defined therebetween,

wherein the head portion extends radially outwardly from one end of the stem portion towards sidewalls of the chamber and defines a cavity between the upper surface of the head portion and an upper surface of the chamber;

using a collar, connecting the showerhead to an upper surface of the chamber adjacent to an end of the stem portion opposite the head portion,

wherein the collar is arranged around the stem portion of the showerhead;

flowing process gas into the cylindrical cavity of the head portion via the stem portion;

flowing the process gas in the cylindrical cavity through the plurality of holes in the lower planar surface to distribute the process gas into the chamber; and

supplying a purge gas through slots of the collar into the cavity between the head portion of the showerhead and the upper surface of the chamber.

2. The method of claim 1 , wherein:

the collar includes a base portion and a stem portion; and

the stem portion of the collar defines an inner cavity that receives the stem portion of the showerhead.

3. The method of claim 2 , further comprising

positioning a plate, including an opening that receives the stem portion of the showerhead, between a lower edge of the stem portion of the collar and the head portion of the showerhead.

4. The method of claim 3 , further comprising directing the purge gas between the plate and the stem portion of the showerhead and between the plate and the head portion of the showerhead.

5. The method of claim 3 , further comprising:

spacing the plate relative to the head portion and the stem portion of the showerhead using a plurality of projections.

6. The method of claim 2 , further comprising:

providing first passages in the base portion of the collar and second passages between an inner surface of the cavity of the stem portion of the collar and the stem portion of the showerhead; and

flowing the purge gas through the first passages to the second passages and from the second passages through the slots.

7. The method of claim 2 , wherein the stem portion of the collar has a circular cross section.

8. The method of claim 2 , further comprising:

providing first passages in the base portion of the collar and second passages in the stem portion of the collar; and

flowing the purge gas through the first passages to the second passages and from the second passages through the slots.

9. The method of claim 1 , further comprising:

arranging N dielectric plates around the stem portion of the showerhead between the head portion of the showerhead and the surface of the chamber,

directing the purge gas using the collar at least one of:

above and below the N dielectric plates; and

between the N dielectric plates,

where N is an integer greater than zero.

10. The method of claim 1 , wherein the substrate processing chamber performs atomic layer deposition.

11. A method comprising:

arranging a substrate in a chamber of a substrate processing system,

wherein the substrate processing system includes a showerhead that is attached to an upper surface of the substrate processing system using a collar, wherein the showerhead includes a head portion having an upper surface;

exposing the substrate to a first precursor for a first predetermined period;

flowing purge gas through a primary purge path and a secondary purge path after the first predetermined period,

wherein the primary purge path flows the purge gas through the showerhead,

wherein the secondary purge path flows the purge gas through slots of the collar into a cavity defined between the head portion of the showerhead and the upper surface of the substrate processing system, and

wherein the secondary purge path removes the first precursor; and

exposing the substrate to a second precursor for a second predetermined period.

12. The method of claim 11 , further comprising:

flowing the purge gas through the primary purge path and the secondary purge path after the second predetermined period,

wherein the secondary purge path removes the second precursor between the head portion of the showerhead and the upper surface of the chamber.

13. The method of claim 12 , further comprising flowing the purge gas through the secondary purge path during the second predetermined period.

14. The method of claim 11 , further comprising flowing the purge gas through the secondary purge path during the first predetermined period.