Etching method

• US 7,402,523 B2
• Filed: 03/31/2006
• Issued: 07/22/2008
• Est. Priority Date: 03/31/2005
• Status: Active Grant

• Current Assignee: Tokyo Electron Limited
• Original Assignee: Tokyo Electron Limited
• Inventors: Nishimura, Eiichi, Orii, Takehiko
• Primary Examiner(s): Ahmed; Shamim
• Application Number:
  US11/393,915
• Publication Number:
  US 20060219660A1
• Time in Patent Office: 844 Days
• Field of Search: 216/41, 216/57, 216/67, 438/704
• US Class Current: 438/704
• CPC Class Codes: H01L 21/31111 by chemical means
• CPC Class Codes: H01L 21/31116 by dry-etching
• CPC Class Codes: H01L 21/31133 by chemical means
• CPC Class Codes: H01L 21/31138 by dry-etching
• CPC Class Codes: H01L 21/31144 using masks
• CPC Class Codes: H01L 21/6708 using mainly spraying means, e.g. nozzles
• CPC Class Codes: H01L 21/76802 by forming openings in dielectrics

Abstract

A method for etching an insulation film through a patterned mask, includes the steps of etching the insulation film until just before an underlayer is about to be exposed by applying a plasma, and modifying a quality of a remaining film of the insulation film by applying another plasma which is different from the plasma used in the above etching process. The method further includes the process of removing the modified remaining film of the insulation film with a liquid chemical. The process of removing the modified remaining film can be also achieved by a dry etching method not employing a plasma.

Claims

1. A method for etching an insulation film through a patterned mask, comprising:

a first process of etching the insulation film until an underlayer is about to be exposed by applying a first plasma of a first processing gas, leaving a bottom portion of the insulation film unetched;

a second process of modifying a quality of the bottom portion of the insulation film by applying a second plasma of a second processing gas, the second plasma being different from the first plasma; and

a third process of removing the bottom portion of the insulation film having a modified film quality with a liquid chemical, wherein the insulation film is formed of a single layer.

3. The method of claim 1, wherein the insulation film is a SiCOH-based low dielectric constant insulation film.

5. The method of claim 1, wherein the mask includes a hard mask.

7. The method of claim 1, wherein the first processing gas is fluorocarbon gas.

9. The method of claim 3, wherein in the second process, a methyl group is mainly removed from the SiCOH-based low dielectric constant insulation film.

10. The method of claim 1, wherein the second processing gas contains at least H₂ gas or O₂ gas.

12. The method of claim 1, wherein the liquid chemical contains at least one of hydrofluoric acid, ammonium fluoride and tetramethyl ammonium hydroxide.

14. The method of claim 1, wherein the underlayer is formed of SiC or SiCN.

18. The method of claim 1, wherein the second processing gas contains H₂ gas.

2. A method for etching an insulation film through a patterned mask, comprising:

a first process of etching the insulation film until an underlayer is about to be exposed by applying a first plasma of a first processing gas, leaving a bottom portion of the insulation film unetched;

a second process of modifying a quality of the bottom portion of the insulation film by applying a second plasma of a second processing gas, the second plasma being different from the first plasma; and

a third process of removing the bottom portion of the insulation film having a modified film quality through a dry etching process using no plasma, wherein the insulation film is formed of a single layer.

4. The method of claim 2, wherein the insulation film is a SiCOH-based low dielectric constant insulation film.

6. The method of claim 2, wherein the mask includes a hard mask.

8. The method of claim 2, wherein the first processing gas is fluorocarbon gas.

11. The method of claim 2, wherein the second processing gas contains at least H₂ gas or O₂ gas.

13. The method of claim 2, wherein the dry etching process using no plasma employs a chemical oxide removal method.

15. The method of claim 2, wherein the underlayer is formed of SiC or SiCN.

16. A method for etching a SiCOH-based low dielectric constant insulation film, comprising:

a first process of etching the SiCOH-based low dielectric constant insulation film with a fluorocarbon gas plasma without exposing an underlayer such that a thickness of a remaining film formed of an unetched bottom portion of the SiCOH-based low dielectric constant insulation film is smaller than or equal to 100 nm;

a second process of removing a methyl group from the remaining film by applying a plasma containing H₂ gas or O₂ gas; and

a third process of removing the remaining film devoid of the methyl group with a solution containing at least one of hydrofluoric acid, ammonium fluoride and tetramethyl animonium hydroxide, wherein the insulation film is formed of a single layer.

17. A method for etching an insulation film through a patterned mask, comprising:

a first process of etching the insulation film until an underlayer is about to be exposed by applying a first plasma of a first processing gas, leaving a bottom portion of the insulation film unetched;

a second process of modifying a quality of the bottom portion of the insulation film by applying a second plasma of a second processing gas, the second plasma being different from the first plasma; and

a third process of removing the bottom portion of the insulation film having a modified film quality, wherein the insulation film is formed of a single layer.