Method for plasma etching a chromium layer through a carbon hard mask suitable for photomask fabrication

• US 20070072435A1
• Filed: 09/28/2005
• Published: 03/29/2007
• Est. Priority Date: 09/28/2005
• Status: Active Grant

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Applied Materials Incorporated
• Inventors: Kumar, Ajay
• Granted Patent: US 7,375,038 B2
• Time in Patent Office: Days
• US Class Current: 438/743
• CPC Class Codes: C23F 4/00 Processes for removing metallic material from surfaces, not provided for in group C23F1/00 or C23F3/00
• CPC Class Codes: G03F 1/80 Etching
• CPC Class Codes: G03F 7/70433 Layout for increasing efficiency or for compensating imaging errors, e.g. layout of exposure fields for reducing focus errors; Use of mask features for increasing efficiency or for compensating imaging errors
• CPC Class Codes: H01J 37/321 the radio frequency energy being inductively coupled to the plasma

Abstract

Methods for etching chromium and forming a photomask using a carbon hard mask are provided. In one embodiment, a method of a chromium layer includes providing a substrate in a processing chamber, the substrate having a chromium layer partially exposed through a patterned carbon hard mask layer, providing a process gas containing chlorine and carbon monoxide into the etching chamber, and maintaining a plasma of the process gas and etching the chromium layer through the carbon hard mask layer. The method of etching a chromium layer through a patterned carbon hard mask layer is useful for fabricating photomasks.

Claims

1. A method of etching a chromium layer, comprising:

providing a substrate in a processing chamber, the substrate having a chromium layer partially exposed through a patterned carbon hard mask;

providing a process gas containing chlorine and carbon monoxide into the processing chamber;

maintaining a plasma formed from the process gas; and

etching the chromium layer through the carbon hard mask.

2. The method of claim 1, wherein the process gas comprises at least one of Cl₂, BCl₃ or HCl.

3. The method of claim 1, wherein providing the process gas comprises:

flowing about 50 to about 1000 sccm of Cl₂ into the processing chamber; and

flowing about 10 to about 500 sccm of CO into the processing chamber.

4. The method of claim 1, wherein providing the process gas comprises:

flowing about 200 to about 400 sccm of Cl₂ into the processing chamber; and

flowing about 100 to about 300 sccm of CO into the processing chamber.

5. The method of claim 1, wherein maintaining the plasma comprises:

applying a plasma source power between about 100 to about 500 Watts.

15. The method of claim 3, wherein introducing the process gas further comprises:

flowing about 200 to about 400 sccm of Cl₂ into the processing chamber; and

flowing about 100 to about 300 sccm of CO into the processing chamber.

6. A method of etching a chromium layer, comprising:

providing a substrate in a process chamber, the substrate having a carbon hard mask disposed over a chromium layer and a quartz layer;

introducing a process gas containing at least one chlorine containing gas and carbon monoxide into the processing chamber;

forming a plasma of the process gas;

biasing the substrate disposed in the processing chamber; and

etching the chromium layer exposed through the patterned hard mask.

7. The method of claim 6, wherein introducing the process gas further comprises:

flowing at least one of Cl₂, BCl₃, or HCl into the processing chamber.

8. The method of claim 6, wherein introducing the process gas comprises:

flowing about 300 sccm of Cl₂ into the processing chamber;

flowing about 150 sccm of CO into the processing chamber;

maintaining chamber pressure at around 3 mTorr;

applying a plasma source power at around 300 Watts; and

supplying a plasma bias power at around 8 Watts.

9. The method of claim 6, wherein introducing the process gas further comprises:

flowing about 50 to about 1000 sccm of Cl₂ into the processing chamber; and

flowing about 10 to about 500 sccm of CO into the processing chamber.

10. The method of claim 6, wherein introducing the process gas further comprises:

flowing about 200 to about 400 sccm of Cl₂ into the processing chamber; and

flowing about 100 to about 300 sccm of CO into the processing chamber.

11. The method of claim 6, wherein biasing further comprises:

biasing the substrate with a power of less than 100 W.

12. The method of claim 11, wherein the biasing further comprises:

pulsing the bias power.

13. A method of forming a photomask, comprising:

forming a carbon hard mask layer on a substrate having a chromium layer and a quartz layer

patterning the carbon hard mask layer to form a hard mask;

introducing process gas containing at least one chlorine containing gas and carbon monoxide into a processing chamber containing the substrate;

forming a plasma of the process gas in the processing chamber;

biasing the substrate disposed in the processing chamber;

etching the chromium layer exposed through the patterned hard mask; and

removing the hard mask.

14. The method of claim 13, wherein the hard mask is removed in-situ the chamber in which the chromium layer is etched.

16. The method of claim 13, wherein the biasing comprises:

biasing the substrate with a power of less than 100 W.

17. The method of claim 13, wherein the biasing further comprises:

pulsing the bias power.

18. The method of claim 13, wherein introducing the process gas further comprises:

flowing at least one of Cl₂, BCl₃, or HCl into the processing chamber.

19. The method of claim 13, wherein forming a carbon hard mask further comprises:

depositing a layer of α

-carbon.