Silicon nitride etching methods

• US 7,288,482 B2
• Filed: 05/04/2005
• Issued: 10/30/2007
• Est. Priority Date: 05/04/2005
• Status: Active Grant

• Current Assignee: Globalfoundries US Incorporated (GlobalFoundries, Inc.), International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Wise, Richard, Panda, Siddhartha, Subramanian, Kamatchi, Murthy, Srikanteswara Dakshina
• Primary Examiner(s): Lebentritt; Michael
• Assistant Examiner(s): Ullah; Elias
• Application Number:
  US10/908,252
• Publication Number:
  US 20060252269A1
• Time in Patent Office: 909 Days
• Field of Search: 438/689, 438/724, 438/757, 438/744
• US Class Current: 438/689
• CPC Class Codes: H01L 21/31116 by dry-etching
• CPC Class Codes: H01L 21/3185 of siliconnitrides

Abstract

Methods of etching silicon nitride material, and more particularly, etching nitride selective to silicon dioxide or silicide, are disclosed. The methods include exposing a substrate having silicon nitride thereon to a plasma including at least one fluorohydrocarbon and a non-carbon containing fluorine source such as sulfur hexafluoride (SF₆). The plasma may also include oxygen (O₂) and the fluorohydrocarbons may include at least one of: trifluoromethane (CHF₃), difluoromethane (CH₂F₂), and methyl fluoride (CH₃F). In an alternative embodiment, the plasma includes one of hydrogen (H₂) and nitrogen trifluoride (NF₃) and one of tetrafluoromethane (CF₄) and octafluorocyclobutane (C₄F₈). The methods are preferably carried out using a low bias voltage, e.g. <100 V.

Claims

1. A method of etching a substrate having a silicon nitride material thereon, the method comprising:

providing a plasma including methyl fluoride (CH₃F) and a non-carbon containing fluorine source including sulfur hexafluoride (SF₆); and

exposing the substrate to the plasma to etch the silicon nitride material selective to at least one of an underlying silicon dioxide and an underlying silicide.

2. The method of claim 1, wherein the plasma further includes trifluoromethane (CHF₃) and oxygen (O₂).

3. The method of claim 2, wherein the plasma includes the following percentage ranges of trifluoromethane (CHF₃), methyl fluoride (CH₃F), oxygen (O₂) and sulfur hexafluoride (SF₆):

10%≦

CHF₃≦

35%, 10%≦

CH₃F≦

35%, 10%≦

O₂≦

50%, and 2%≦

SF₆≦

10%.

4. The method of claim 1, wherein the plasma providing step includes providing a pressure of no less than 50 mT and no greater than 100 mT and a chamber power of no less than 0.05 W/cc and no greater than 0.25 W/cc.

5. The method of claim 1 wherein the underlying silicide is chosen from the group consisting of:

cobalt silicide and nickel silicide.

6. The method of claim 1, wherein the plasma is a transformer coupled plasma having a bias voltage of no greater than 100 V.

7. The method of claim 6, wherein the bias voltage is no greater than 50 V.

8. A method of etching a substrate having a silicon nitride material thereon, the method comprising:

providing a plasma including hydrogen (H₂) and octafluorocyclobutane (C₄F₈); and

exposing the substrate to the plasma to etch the silicon nitride material selective to at least one of an underlying silicon dioxide and an underlying silicide.

9. The method of claim 8, wherein the plasma providing step includes providing a pressure of no less than 50 mT and no greater than 100 mT and a chamber power of no less than 0.05 W/cc and no greater than 0.25 W/cc.

10. The method of claim 8, wherein the underlying silicide is chosen from the group consisting of:

cobalt silicide and nickel silicide.

11. The method of claim 8, wherein the plasma is a transformer coupled plasma having a bias voltage of no greater than 100 V.

12. The method of claim 11, wherein the bias voltage is no greater than 50 V.

13. A method of etching a substrate having a silicon nitride material thereon, the method comprising:

providing a plasma including oxygen (O₂), a non-carbon containing fluorine source including sulfur-hexafluorine (SF₆) and methyl fluoride (CH₃F); and

exposing the substrate to the plasma to etch the silicon nitride material selective to at least one of an underlying silicon dioxide and an underlying silicide.

14. The method of claim 13, wherein the plasma includes the following percentage ranges of trifluoromethane (CHF₃), methyl fluoride (CH₃F), oxygen (O₂) and sulfur hexafluoride (SF₆):

10%≦

CHF₃≦

35%, 10%≦

CH₃F≦

35%, 10%≦

O₂ ≦

50%, and 2%≦

SF₆≦

10%.

15. The method of claim 13, wherein the plasma providing step includes providing a pressure of no less than 50 mT and no greater than 100 mT and a chamber power of no less than 0.05 W/cc and no greater than 0.25 W/cc.

16. The method of claim 13, wherein the underlying silicide is chosen from the group consisting of:

cobalt silicide and nickel silicide.

17. The method of claim 13, wherein the plasma is a transformer coupled plasma having a bias voltage of no greater than 100 V.

18. The method of claim 17, wherein the bias voltage is no greater than 50 V.