Gas mixture for removing photoresist and post etch residue from low-k dielectric material and method of use thereof

• US 20070054496A1
• Filed: 09/08/2005
• Published: 03/08/2007
• Est. Priority Date: 09/08/2005
• Status: Active Grant

• Current Assignee: Lam Research Corporation
• Original Assignee: Lam Research Corporation
• Inventors: Paduraru, Cristian, Jensen, Alan, Schaefer, David, Choi, Tom, Charatan, Robert
• Granted Patent: US 7,479,457 B2
• Time in Patent Office: Days
• US Class Current: 438/725
• CPC Class Codes: G03F 7/427 using plasma means only

Abstract

Atomic oxygen generated in oxygen stripping plasmas reacts with and damages low-k dielectric materials during stripping of dielectric post etch residues. While damage of low-k dielectric materials during stripping of dielectric post etch residues is lower with hydrogen stripping plasmas, hydrogen stripping plasmas exhibit lower strip rates. Inclusion of oxygen in a hydrogen stripping plasma improves both photoresist strip rate and uniformity, while maintaining a hydrogen to oxygen ratio avoids low-k dielectric material damage.

Claims

1. A method of removing photoresist and post etch residue from a semiconductor substrate having a layer of low-k dielectric material comprising:

introducing a semiconductor substrate having a layer of low-k dielectric material having photoresist and post etch residue thereon into a downstream reaction chamber;

generating plasma comprising reactive species in an upstream applicator, wherein the reactive species comprise atomic hydrogen and atomic oxygen, wherein atomic oxygen passivates applicator surfaces exposed to the plasma, wherein the plasma is generated from a gas mixture comprising oxygen, hydrogen, and inert carrier gas, and wherein the volume ratio of hydrogen to oxygen is greater than 2;

1; and

introducing the reactive species into the downstream reaction chamber, wherein atomic hydrogen removes photoresist and post etch residue from the low-k dielectric material.

2. The method of claim 1, wherein the gas mixture comprises 0.05-0.3% by volume oxygen and 1-10% by volume hydrogen.

3. The method of claim 2, wherein the gas mixture comprises about 0.1% by volume oxygen.

4. The method of claim 3, wherein the reactive species introduced into the downstream reaction chamber comprise less than about 0.1% by volume oxygen.

5. The method of claim 1, wherein the inert carrier gas is selected from the group consisting of helium, argon, and mixtures thereof.

6. The method of claim 5, wherein the inert carrier gas is helium and further wherein hydrogen and helium are supplied as H₂He.

7. The method of claim 1, wherein the oxygen is supplied as O₂.

8. The method of claim 1, wherein the gas mixture has a total flow rate of up to about 6000-7000 standard cubic centimeters per minute.

9. The method of claim 1, wherein the semiconductor substrate is a semiconductor wafer supported on a substrate support heated to a temperature of at least 250°

C.

10. The method of claim 1, wherein the volume ratio of hydrogen to oxygen is greater than 5:

1, greater than 10;

1, greater than 20;

1, or greater than 40;

1.

11. The method of claim 1, wherein the reactive species are introduced into the downstream reaction chamber through a quartz baffle and further wherein atomic oxygen passivates baffle surfaces exposed to the plasma.

12. The method of claim 1, wherein the reactive species are exposed to a quartz chamber liner before being introduced into the downstream reaction chamber and further wherein atomic oxygen passivates chamber liner surfaces exposed to the plasma.

13. The method of claim 1, wherein the upstream applicator is comprised of quartz.

14. The method of claim 1, further comprising seasoning the reaction chamber with an oxygen-containing gas, which is energized into a plasma state for a time sufficient to remove polymer byproducts deposited on chamber surfaces, prior to introducing the semiconductor substrate into the downstream reaction chamber.

15. A method of sequentially processing semiconductor wafers comprising:

a) removing photoresist and post etch residue from a semiconductor substrate according to the method of claim 14;

b) removing the semiconductor wafer from the downstream reaction chamber; and

c) repeating steps a) and b).

16. A gas mixture for removing photoresist and post etch residue from a semiconductor substrate having a layer of low-k dielectric material comprising:

hydrogen and oxygen in a volume ratio of greater than 2;

1; and

inert carrier gas,

wherein plasma generated from the gas mixture comprises atomic hydrogen and atomic oxygen, wherein atomic oxygen passivates surfaces exposed to the plasma, and wherein atomic hydrogen removes photoresist and post etch residue from the low-k dielectric material.

17. The gas mixture of claim 16, comprising:

0.05-0.3% by volume oxygen; and

1-10% by volume hydrogen.

18. The gas mixture of claim 17, comprising about 0.1% by volume oxygen.

19. The gas mixture of claim 16, wherein the inert carrier gas is helium, the hydrogen and helium are supplied as H₂He, and the oxygen is supplied as O₂.

20. The gas mixture of claim 16, wherein the volume ratio of hydrogen to oxygen is greater than 5:

1, greater than 10;

1, greater than 20;

1, or greater than 40;

1.