Method for enhancing etching of TiSix

• US 6,544,896 B1
• Filed: 10/10/2000
• Issued: 04/08/2003
• Est. Priority Date: 03/05/1999
• Status: Expired due to Fees

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Applied Materials Incorporated
• Inventors: Kusuki, Takakazu, Xu, Songlin, Qian, Xueyu
• Primary Examiner(s): Utech, Benjamin L.
• Assistant Examiner(s): Tran, Binh X
• Application Number:
  US09/686,208
• Time in Patent Office: 910 Days
• Field of Search: 438/710, 438/711, 438/714, 438/715, 438/719, 438/720, 438/721
• US Class Current: 438/710
• CPC Class Codes: H01L 21/02071 the processing being a delineation, e.g. RIE, of conductive layers
• CPC Class Codes: H01L 21/32137 of silicon-containing layers

Abstract

Conventional methods of etching TiSi_x use Cl₂ or HBr as the plasma etchant. However, these methods can lead to undesirable residues, due to the presence of silicon nodules in the TiSi_x The present invention overcomes the residue problem by adding a fluorine containing gas to the plasma etchant, which is then able to effectively etch the Si nodules at an etch rate which is approximately the same as the etch rate of the TiSi_x, so that the undesirable residue is not formed. A method of etching TiSi_x is provided, wherein the surface of the TiSi_x is exposed, typically through a patterned mask, to a plasma etchant. The plasma etchant comprises (i) at least one fluorine containing gas, such as SF₆, NF₃, C_xF_y, and compatible mixtures of such gases; and (ii) a gas selected from the group consisting of HBr, Cl₂, and combinations thereof.

Claims

1. A method of etching a layer of TiSi_x, while reducing a micro masking effect caused by silicon nodules present in said layer of TiSi_x, by exposing said layer of TiSi_x to a plasma generated from a plasma source gas containing less than about 20% by volume of an inorganic fluorine-containing compound, wherein said inorganic fluorine-containing compound consists essentially of NF₃, and wherein the temperature of a surface of said TiSi_x layer during etching is within the range of about 40°

C. to about 80°

C.

3. The method of claim 1 or claim 2, wherein said etching is carried out with a bias applied to said layer of TiSi_x, whereby said etching is substantially anisotropic.

4. The method of claim 3, wherein said plasma source gas further comprises O₂.

9. The method of claim 1 or claim 2, wherein said temperature of said surface of said TiSi_x layer during etching is within a range of about 40°

C. to about 50°

C.

10. The method of claim 1 or claim 2, wherein said plasma source gas does not include any hydrogen-containing gases.

11. The method of claim 1 or claim 2, wherein a selectivity of TiSi_x:

Si nodules is less than about 1.5;

1.

12. The method of claim 11, wherein a selectivity of TiSi_x:

Si nodules is less than about 1.2;

1.

13. The method of claim 12, wherein a selectivity of TiSi_x:

Si nodules is about 1.0;

1.

2. A method of etching a layer of TiSi_x, while reducing a micro masking effect caused by silicon nodules present in said layer of TiSi_x, by exposing said layer of TiSi_x to a plasma etchant generated from a plasma source gas comprising less than about 20% by volume of an inorganic fluorine-containing compound, wherein said inorganic fluorine-containing compound consists essentially of NF₃, and a gas selected from the group consisting of HBr, Cl₂, and combinations thereof, and wherein the temperature of a surface of said TiSi_x layer during etching is within the range of about 40°

C. to about 80°

C.

5. The method of claim 2, wherein said gas selected from the group consisting of HBr, Cl₂, and combinations thereof makes up between about 60% to about 95% by volume of said plasma source gas.

6. The method of claim 2, wherein said gas selected from the group consisting of HBr, Cl₂ and combinations thereof consists essentially of HBr.

7. The method of claim 2, wherein said gas selected from the group consisting of HBr, Cl₂ and combinations thereof consists essentially of Cl₂.

8. The method of claim 2, wherein a bias power is applied to said TiSi_x layer to increase ion bombardment.

14. A method of etching a layer of TiSi_x, while reducing a micro masking effect caused by silicon nodules present in said layer of TiSi_x, by exposing said layer of TiSi_x to a plasma generated from a plasma source gas containing less than about 40% by volume of an organic fluorine-containing compound, or less than about 20% by volume of an inorganic fluorine-containing compound, wherein the temperature of a surface of said TiSi_x layer during etching is within the range of about 40°

C. to about 80°

C., and wherein a selectivity of TiSi_x;

Si nodules is less than about 1.2;

1.

16. The method of claim 14 or claim 15 wherein a selectivity of TiSi_x:

Si nodules is about 1.0;

1.

15. A method of etching a layer of TiSi_x, while reducing a micro masking effect caused by silicon nodules present in said layer of TiSi_x, by exposing said layer of TiSi_x to a plasma etchant generated from a plasma source gas comprising less than about 40% by volume of an organic fluorine-containing compound, or less than about 20% by volume of an inorganic fluorine-containing compound, and a gas selected from the group consisting of HBr, Cl₂, and combinations thereof, wherein the temperature of a surface of said TiSi_x layer during etching is within the range of about 40°

C. to about 80°

C., and wherein a selectivity of TiSi_x;

Si nodules is less than about 1.2;

1.