METHOD OF POLISHING A LOW-K SUBSTRATE

• US 20170194160A1
• Filed: 01/06/2017
• Published: 07/06/2017
• Est. Priority Date: 01/06/2016
• Status: Abandoned Application

• Current Assignee: Cabot Microelectronics Corporation (Entegris Incorporated)
• Original Assignee: Cabot Microelectronics Corporation (Entegris Incorporated)
• Inventors: PALLIKKARA KUTTIATOOR, Sudeep, JIA, Renhe, CHEN, Kuen-Min, KRAFT, Steven, CARTER, Phillip W.
• Application Number:
  US15/399,810
• Publication Number:
  US 20170194160A1
• Time in Patent Office: Days
• CPC Class Codes: C09G 1/02 containing abrasives or grinding agents abrasives as such C09K3/14; polishing of semi-conductors H01L
• CPC Class Codes: C09K 3/1409 Abrasive particles per se preparation of diamond C01B32/25
• CPC Class Codes: C09K 3/1463 Aqueous liquid suspensions
• CPC Class Codes: H01L 21/31053 involving a dielectric removal step

Abstract

Disclosed is a method of chemically-mechanically polishing a substrate. The method comprises, consists of, or consists essentially of (a) contacting a substrate containing a low-k dielectric composition, which includes less than about 80% by weight of carbon, with a polishing pad and a chemical-mechanical polishing composition comprising water and abrasive particles having a positive surface charge, wherein the polishing composition has a pH of from about 3 to about 6; (b) moving the polishing pad and the chemical-mechanical polishing composition relative to the substrate; and (c) abrading at least a portion of the substrate to polish the substrate. In some embodiments, the low-k dielectric composition is carbon-doped silicon oxide.

Claims

1. A method of chemically-mechanically polishing a substrate, the method comprising:

(a) contacting a substrate containing a low-k dielectric composition, which includes less than about 80% by weight of carbon, with a polishing pad and a chemical-mechanical polishing composition comprising water and abrasive particles having a positive surface charge, wherein the polishing composition has a pH of from about 3 to about 6;

(b) moving the polishing pad and the chemical-mechanical polishing composition relative to the substrate; and

(c) abrading at least a portion of the substrate to polish the substrate.

2. The method of claim 1, wherein the low-k dielectric composition includes less than about 50% by weight of carbon.

3. The method of claim 1, wherein the low-k dielectric composition includes less than about 30% by weight of carbon.

4. The method of claim 1, wherein the low-k dielectric composition is carbon-doped silicon oxide.

5. The method of claim 4, wherein the carbon-doped silicon oxide includes at least 35% by weight silicon.

6. The method of claim 4, wherein the carbon-doped silicon oxide includes at least 45% by weight oxygen.

7. The method of claim 1, wherein the abrasive particles have a zeta potential of at least about +10 mV.

8. The method of claim 1, wherein the abrasive particles include wet process ceria.

9. The method of claim 1, wherein the abrasive particles are present in an amount of about 0.05 wt. % to about 2 wt. % of the polishing composition.

10. The method of claim 1, wherein the pH of the composition is from about 3 to about 5.6.

11. The method of claim 10, wherein the pH of the composition is from about 5 to about 5.6.

12. The method of claim 1, wherein the polishing composition further comprises an ionic polymer of formula (I):

13. The method of any claim 12, wherein X¹ and X² are both —

COOH.

14. The method of claim 12, wherein Z¹ and Z² are both O, and R¹, R², R³, and R⁴ are hydrogen.

15. The method of claim 12, wherein the ionic polymer has a molecular weight of about 500 g/mol to about 10,000 g/mol, and wherein n is an integer with a value of 8 or greater.

16. The method of claim 12, wherein the ionic polymer is a polyethylene glycol diacid.

17. The method of claim 12, wherein the ionic polymer is present in an amount of about 0.01 wt. % to about 0.5 wt. % of the polishing composition.

18. The method of claim 1, wherein the polishing composition further comprises a polyhydroxy aromatic compound.

19. The method of claim 18, wherein the polyhydroxy aromatic compound is selected from 1,3-dihydroxybenzene and 1,3,5-trihydroxybenzene.

20. The method of claim 18, wherein the polyhydroxy aromatic compound is 1,3,5-trihydroxybenzene.

21. The method of claim 18, wherein the polyhydroxy aromatic compound is present in an amount of about 0 wt. % to about 0.5 wt. % of the polishing composition.

22. The method of claim 1, wherein the polishing composition further comprises polyvinyl alcohol.

23. The method of claim 22, wherein the polyvinyl alcohol has a molecular weight of about 20,000 g/mol to about 200,000 g/mol.

24. The method of claim 22, wherein the polyvinyl alcohol is a branched polyvinyl alcohol.

25. The method of claim 22, wherein the polyvinyl alcohol is present in an amount of about 0.05 wt. % to about 0.5 wt. % of the polishing composition.

26. The method of claim 1, wherein abrading at least a portion of the surface of the substrate removes about 100-500 Å

/min of silicon oxide depending on the pH from the surface of the substrate.

27. The method of claim 1, wherein the substrate further contains silicon nitride, and wherein abrading at least a portion of the surface of the substrate removes less than about 20 Å

/min of silicon nitride from the surface of the substrate.