Method for plasma etching a chromium layer suitable for photomask fabrication

• US 20060166107A1
• Filed: 01/27/2005
• Published: 07/27/2006
• Est. Priority Date: 01/27/2005
• Status: Active Grant

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Applied Materials Incorporated
• Inventors: Tam, Simon, Kumar, Ajay, Tran, Jeffrey X., Chandrachood, Madhavi, Grimbergen, Michael, Krishnamurthy, Ramesh, Chen, Xiaoyi
• Granted Patent: US 7,829,243 B2
• Time in Patent Office: Days
• US Class Current: 430/5
• 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 1/30 Alternating PSM, e.g. Levenson-Shibuya PSM; Preparation thereof
• CPC Class Codes: G03F 1/54 Absorbers, e.g. of opaque materials
• CPC Class Codes: G03F 1/80 Etching

Abstract

A method for etching a chromium layer is provided herein. In one embodiment, a method for etching a chromium layer includes providing a filmstack in an etching chamber, the filmstack having a chromium layer partially exposed through a patterned layer, providing at least one halogen containing process gas to a processing chamber, biasing the layer disposed on a substrate support in the processing chamber with a plurality of power pulses less than 600 Watts, and etching the chromium layer through a patterned mask. The method for plasma etching a chromium layer described herein is particularly suitable for fabricating photomasks.

Claims

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

providing a filmstack in an etching chamber, the filmstack having a chromium layer partially exposed through a patterned layer;

providing at least one halogen containing process gas to a processing chamber;

forming a plasma from the process gases;

biasing the layer disposed on a substrate support in the processing chamber with a plurality of power pulses less than 600 Watts; and

etching the chromium layer through a patterned mask.

2. The method of claim 1, wherein the step of providing at least one halogen containing process gas comprises:

flowing at least one of fluorocarbon gas, Cl₂, HBr, HCl, CF₄ and CHF₃ into the processing chamber.

3. The method of claim 1, wherein the step of providing at least one halogen containing process gas comprises:

flowing O₂ into the processing chamber.

4. The method of claim 1, wherein the step of providing at least one halogen containing process gas comprises:

flowing about 2 to about 50 sccm of CF₄ into the processing chamber; and

flowing about 2 to about 50 sccm of CHF₃ into the processing chamber.

5. The method of claim 2, wherein the step of providing at least one halogen containing process gas comprises:

flowing an inert gas into the processing chamber selected from the group consisting of Ar, He, Xe, Ne and Kr.

6. The method of claim 1, wherein the step of biasing comprises:

pulsing power with a duty cycle between about 10 to about 95 percent.

7. The method of claim 1, wherein the step of biasing further comprises:

pulsing power at a frequency between about 1 to about 10 kHz.

8. The method of claim 1, wherein the step of forming the plasma further comprises:

providing a plasma power of between about 250 to about 600 Watts.

9. The method of claim 1, wherein the step of forming the plasma further comprises:

forming a plasma above an ion-radical shield; and

etching the chromium layer below the ion-radical shield.

10. The method of claim 1, wherein the patterned layer is formed by a method comprising:

patterning a layer of resist to form at least one opening in the resist layer; and

depositing a conformal protective layer on the patterned resist.

11. A method of forming a photomask, comprising:

a) patterning a mask layer on a photomask layer containing at least a chromium layer;

b) etching the chromium layer through the mask layer using an etch process comprising;

providing at least one halogen containing process gas to a processing chamber;

biasing the photomask layer disposed on a substrate support in the processing chamber with a plurality of power pulses less than 600 Watts; and

maintaining a plasma of the process gas with the processing chamber; and

c) removing the mask layer.

12. The method of claim 11, wherein the step of providing at least one halogen containing process gas comprises:

flowing at least one of fluorocarbon gas, Cl₂, HBr, HCl, CF₄ and CHF₃ into the processing chamber; and

.

flowing an inert gas into the processing chamber selected from the group consisting of Ar, He, Xe, Ne and Kr.

13. The method of claim 11, wherein the step of providing at least one halogen containing process gas comprises:

flowing O₂ into the processing chamber.

14. The method of claim 11, wherein the step of biasing comprises:

pulsing power with a duty cycle between about 10 to about 95 percent.

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

pulsing power at a frequency between about 1 to about 10 kHz.

16. The method of claim 11, wherein the step of forming the plasma further comprises:

providing a plasma power of between about 250 to about 600 Watts.

17. The method of claim 11, wherein the step of forming the plasma further comprises:

forming a plasma above an ion-radical shield; and

etching the chromium layer below the ion-radical shield.

18. The method of claim 11, wherein the step of patterning a mask comprises:

patterning a layer of resist to form at least one opening in the resist layer;

depositing a conformal protective layer on the patterned resist; and

removing portions of the protective layer to expose the chromium layer for etching.

19. The method of claim 11 further comprising:

etching an attenuating layer using the patterned chromium layer.

20. The method of claim 19 further comprising:

removing the patterned chromium layer.

21. The method of claim 11 further comprising:

forming a patterned resist layer on the patterned chromium layer, wherein at least a first opening in the chromium layer is filled with resist and at least a second opening in the chromium layer is open through the patterned resist; and

etching the quartz layer through the second opening.

22. A method of forming a photomask, comprising:

patterning a resist layer on a film stack having a chromium-containing layer;

plasma etching the chromium-containing layer suing the patterned resist layer as an etch mask to expose an underlying layer;

applying a pulsed bias power of less than 600 Watts during etching of the chromium containing layer; and

removing the resist layer.

23. The method of claim 22 further comprising;

depositing a conformal protective layer on the patterned resist layer, the protective layer coating side walls of openings formed in the resist layer; and

etching a chromium-containing layer using the patterned resist layer and protective layer as an etch mask.

24. The method of claim 22 further comprising:

etching the underlying layer to form an opening, wherein the underlying layer includes molybdenum;

pattering a second resist layer on the patterned underlying layer, the patterned second resist layer covering the opening formed in the underlying layer;

etching the chromium-containing layer using the patterned second resist layer as an etch mask; and

removing the patterned second resist layer.

25. The method of claim 22 further comprising:

etching the underlying layer to form an opening, wherein the underlying layer includes quartz; and

removing the chromium-containing layer.

26. A method of forming a photomask, comprising:

providing a film stack having a chromium-containing layer on a substrate support disposed in a processing chamber having a ion-radial shield spaced above the film stack;

patterning a resist layer disposed on the film stack;

plasma etching the chromium-containing layer using the patterned resist layer as an etch mask to expose an underlying layer;

applying a pulsed bias power of less than 600 Watts during etching of the chromium containing layer; and

removing the resist layer in-situ the processing chamber.