Methods for polymer removal following etch-stop layer etch

• US 6,713,402 B2
• Filed: 05/31/2002
• Issued: 03/30/2004
• Est. Priority Date: 05/31/2002
• Status: Active Grant

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Smith, Patricia Beauregard, Park, Heungsoo
• Primary Examiner(s): Niebling, John F.
• Assistant Examiner(s): Luk, Olivia T.
• Application Number:
  US10/161,502
• Publication Number:
  US 20030224595A1
• Time in Patent Office: 669 Days
• Field of Search: 438/710, 438/725, 438/624, 438/786, 438/798, 438/622, 438/597, 438/637, 438/706, 315/111.51
• US Class Current: 438/710
• CPC Class Codes: H01L 21/02063 the processing being the formation of vias or contact holes
• CPC Class Codes: H01L 21/31116 by dry-etching
• CPC Class Codes: H01L 21/31138 by dry-etching
• CPC Class Codes: H01L 21/76807 for dual damascene structures
• CPC Class Codes: H01L 21/76814 post-treatment or after-treatment, e.g. cleaning or removal of oxides on underlying conductors
• CPC Class Codes: H01L 21/76838 characterised by the formation and the after-treatment of the conductors etching for patterning the conductors H01L21/3213

Abstract

Cleaning methods are disclosed for removing sidewall polymers from interconnect vias or trenches, wherein a wafer is exposed to a plasma comprising hydrogen and an inert gas in a plasma cleaning chamber following etch-stop etching.

Claims

1. A method for creating an interconnect structure associated with a semiconductor wafer, the method comprising:

forming a cavity in a dielectric layer over the semiconductor wafer to expose a portion of an etch-stop layer underlying the dielectric layer;

performing an etch-stop etch process to remove the exposed portion of the etch-stop layer in the cavity and to expose a portion of a conductive feature underlying the etch-stop layer; and

removing polymer from sidewalls in the cavity after the etch-stop etch process using a plasma comprising hydrogen or a hydrogen-containing gas and one of argon, helium, neon, and xenon.

2. The method of claim 1, wherein performing the etch-stop etch process comprises performing an RIE etch in a first process chamber and wherein removing the polymer from the sidewalls in the cavity comprises exposing the wafer to the plasma in a second process chamber.

3. The method of claim 2, wherein the plasma comprises at least about 40% hydrogen or other hydrogen-containing gas.

4. The method of claim 3, wherein the plasma comprises about 50% or more and about 70% or less hydrogen or other hydrogen-containing gas.

5. The method of claim 4, wherein the plasma comprises about 60% hydrogen and about 40% of one of argon, helium, neon, and xenon.

6. The method of claim 1, wherein the etch-stop etch process and removing polymer from the sidewalls are performed in a single process chamber.

7. The method of claim 6, wherein removing polymer from the sidewalls comprises exposing the water to a first plasma comprising oxygen and thereafter exposing the wafer to a second plasma comprising hydrogen or a hydrogen-containing gas and one of argon, helium, neon, and xenon.

8. The method of claim 6, the plasma further comprises oxygen.

9. The method of claim 1, wherein removing polymer from the sidewalls comprises exposing the wafer to a first plasma comprising oxygen and thereafter exposing the water to a second plasma comprising hydrogen or a hydrogen-containing gas and one of argon, helium, neon, and xenon.

10. The method of claim 1, wherein removing polymer from sidewalls comprises creating a plasma in a plasma cleaning chamber using a gas comprising about 80% hydrogen and about 40% argon and exposing the wafer to the plasma in the plasma cleaning chamber.

11. The method of claim 10, wherein the dielectric layer comprises a low-k dielectric material.

12. The method of claim 10, wherein the dielectric layer comprises organo-silicate glass material.

13. The method of claim 1, wherein the dielectric layer comprises organo-silicate glass material.

14. The method of claim 13, wherein removing polymer from sidewalls comprises creating a plasma in a plasma cleaning chamber using a gas free of nitrogen and exposing the wafer to the plasma in th plasma gas. chamber, the gas comprising at least about 40% hydrogen, or a hydrogen-containing gas.

15. The method of claim 14, wherein the gas comprises about 60% hydrogen and about 40% argon.

16. The method of claim 14, wherein performing the etch-stop etch process comprises performing an RIE etch In an etch chamber, further comprising transferring the wafer from the etch chamber to the plasma cleaning chamber after the etch-stop etch process and before removing the polymer.

17. The method of claim 14:

wherein the wafer comprises a conductive feature formed over a substrate, a lower etch-stop layer formed of silicon carbide material over the conductive feature, a lower dielectric layer farmed of organo-silicate glass material over the lower etch-stop layer, an upper etch-stop layer formed over the lower dielectric layer, an upper dielectric layer formed over the upper etch-stop layer, and a hard mask layer formed over the upper dielectric layer;

wherein forming the cavity comprises etching a via through first portions of the hard mask layer, the upper dielectric layer, the upper etch-stop layer, and the lower dielectric layer to expose a first portion of the tower etch-stop layer in a prospective via region of the wafer, and etching a trench through second portions of the hard mask layer and the upper dielectric layer to expose a second portion of the upper etch-stop layer in a prospective trench region of the wafer; and

wherein performing the etch-stop etch process comprises removing the exposed first portion of the lower etch-stop layer to expose the portion of the conductive feature in the prospective via region.

18. The method of claim 17, further comprising forming a barrier layer in the cavity, filling the cavity with conductive material, and planarizing the wafer following removal of the polymer from the sidewalls.

19. The method of claim 14, wherein removing polymer from sidewalls comprises creating the plasma and exposing the wafer to the plasma in the plasma cleaning chamber for about 20 seconds or more and about 40 seconds or less using a gas flow rate of about 3000 sccm or more and about 4000 sccm or less, a chamber temperature of about 250 degrees C., and a pressure of about 0.5 torr or more and about 1.0 torr or less.

20. A method of removing polymer from a cavity during formation of Interconnect structures in the manufacture of a semiconductor wafer, the method comprising:

etching an exposed portion of an etch-stop layer in the cavity in a first process chamber to expose a portion of a conductive feature underlying the etch-stop layer; and

removing polymer from sidewalls in the cavity in a second process chamber using a plasma comprising hydrogen and one of the following gases;

argon, helium, neon, or xenon.

21. The method of claim 20, wherein the plasma comprises about 60% hydrogen or other hydrogen-containing gas and about 40% of argon, helium, neon, or xenon.

22. The method of claim 21, wherein removing polymer from sidewalls comprises creating the plasma and exposing the wafer to the plasma in a plasma cleaning chamber for about 20 seconds or more and about 40 seconds or less using a gas flow rate of about 3000 sccm or more and about 4000 sccm or less, a chamber temperature of about 250 degrees C., and a pressure of about 0.5 torr or more and about 1.0 torr or less.

23. A method of cleaning polymer from a cavity in a dual damascene interconnect structure of a semiconductor wafer, comprising;

placing the wafer in a plasma cleaning chamber; and

exposing the wafer to a plasma comprising hydrogen or other hydrogen-containing gas and one of argon, helium, neon, and xenon in the plasma cleaning chamber.

24. The method of claim 23, wherein exposing the wafer comprises:

creating the plasma in the plasma cleaning chamber using a nitrogen-free gas comprising about 60% hydrogen and about 40% argon; and

exposing the wafer to the plasma in the plasma cleaning chamber for about 20 seconds or more and about 40 seconds or less using a gas flow rate of about 3000 sccm or more and about 4000 sccm or less, a chamber temperature of about 250 degrees C., and a pressure of about 0.5 torr or more and about 1.0 torr or less.

25. A method of cleaning polymer from a cavity in a single damascene interconnect structure of a semiconductor wafer, comprising:

placing the wafer in a plasma cleaning chamber; and

exposing the wafer to a plasma comprising hydrogen or other hydrogen-containing gas and one of argon, helium, neon, and xenon in the plasma cleaning chamber.

26. The method of claim 25, wherein exposing the wafer comprises:

creating the plasma in the plasma cleaning chamber using a nitrogen-free gas comprising about 60% hydrogen and about 40% argon; and

exposing the wafer to the plasma in the plasma cleaning chamber for about 20 seconds or more and about 40 seconds or less using a gas flow rate of about 3000 sccm or more and about 4000 sccm or less, a chamber temperature of about 250 degrees C., and a pressure of about 0.5 torr or more and about 1.0 torr or less.

27. A method of cleaning polymer from a cavity in a semiconductor wafer, comprising:

performing an etch process which leaves polymeric residue in a cavity in the wafer; and

exposing the wafer to a plasma comprising hydrogen or other hydrogen-containing gas and one of argon, helium, neon, and xenon to remove at least a portion of the polymeric residue from the cavity.

28. The method of claim 27, wherein exposing the wafer comprises creating the plasma using a nitrogen-free gas comprising about 60% hydrogen and about 40% argon and exposing the wafer to the plasma for about 20 seconds or more and about 40 seconds or less using a gas flow rate of about 3000 sccm or more and about 4000 sccm or less, a chamber temperature of about 250 degrees C, and a pressure of about 0.5 torr or more and about 1.0 torr or less.