METHOD AND APPARATUS FOR PHOTOMASK PLASMA ETCHING

• US 20080099431A1
• Filed: 10/30/2006
• Published: 05/01/2008
• Est. Priority Date: 10/30/2006
• Status: Active Grant

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Applied Materials Incorporated
• Inventors: Bivens, Darin, Kumar, Ajay, Panayil, Sheeba J., Chandrachood, Madhavi R., Ouye, Alan Hiroshi, Sabharwal, Amitabh, Lewington, Richard
• Granted Patent: US 7,943,005 B2
• Time in Patent Office: Days
• US Class Current: 216/44
• CPC Class Codes: H01J 37/32422 Arrangement for selecting ions or species in the plasma
• CPC Class Codes: H01J 37/3244 Gas supply means
• CPC Class Codes: H01J 37/32449 Gas control, e.g. control of the gas flow

Abstract

A method and apparatus for etching photomasks is provided herein. In one embodiment, the apparatus comprises a process chamber having a support pedestal adapted for receiving a photomask. An ion-neutral shield is disposed above the pedestal and a deflector plate assembly is provided above the ion-neutral shield. The deflector plate assembly defines a gas flow direction for process gases towards the ion-neutral shield, while the ion-neutral shield is used to establish a desired distribution of ion and neutral species in a plasma for etching the photomask.

Claims

1. An apparatus for plasma etching, comprising:

a process chamber;

a substrate support pedestal disposed in the process chamber;

an RF power source for forming a plasma within the chamber;

a shield disposed in the chamber above the pedestal and below a plasma forming region in the chamber, the shield configured to control a distribution of ionic and neutral species of the plasma;

at least one gas inlet for providing a gas flow into the chamber; and

a deflector plate assembly disposed above the shield, the deflector plate assembly configured to provide a predetermined gas flow pattern between the gas inlet and the shield.

2. The apparatus of claim 1, wherein the deflector plate assembly comprises a first plate having an aperture.

3. The apparatus of claim 2, wherein the at least one gas inlet is disposed above the first plate.

4. The apparatus of claim 2, wherein the aperture is located at a center of the first plate and substantially aligned with a center of the shield.

5. The apparatus for claim 2, wherein the aperture is circular and has a diameter between about 25.4 mm to about 76.2 mm.

6. The apparatus of claim 2, wherein the deflector plate assembly further comprises a second plate disposed above the first plate, the second plate having a downwardly protruding portion disposed above the aperture.

7. The apparatus of claim 6, wherein the downwardly protruding portion is substantially aligned with the aperture of the first plate.

8. The apparatus of claim 6, wherein the downwardly protruding portion has a first end at a plane of the second plate and a distal end, the first end having a lateral dimension that is larger than a lateral dimension at the distal end.

9. The apparatus of claim 8, wherein the lateral dimension at the base of the protruding portion is larger than a diameter of the aperture of the first plate.

10. The apparatus of claim 1, wherein the first plate of the deflector plate assembly is attached to the shield by a support assembly.

11. The apparatus of claim 10, wherein the first plate is supported in a substantially parallel, spaced apart relation with respect to the shield.

12. The apparatus of claim 1, wherein the deflector plate assembly is fabricated from at least one of ceramic, quartz, or anodized aluminum.

13. The apparatus of claim 1, wherein the support pedestal is configured for supporting a photomask.

14. The apparatus of claim 1, wherein the shield comprises two zones having at least one characteristic different from each other, the at least one characteristic being one of material or potential bias.

15. The apparatus of claim 14, wherein each of the two zones comprises a material with a dielectric constant different from each other, the material being selected from the group consisting of anodized aluminum, ceramics, alumina, yttria, and materials having a dielectric constant higher than about 4.

16. The apparatus of claim 14, wherein the two zones of the shield have respective potential bias different from each other.

17. The apparatus of claim 1, wherein the shield comprises a plurality of zones having at least one characteristic different from each other, the at least one characteristic being one of material or potential bias.

18. A method of etching a photomask in a process chamber, comprising:

placing a photomask on a support pedestal;

providing a shield above the support pedestal inside the chamber;

introducing a process gas into the process chamber through at least one inlet;

providing a predetermined gas flow pattern between the gas inlet and the shield by disposing a deflector plate assembly above the shield;

forming a plasma from the process gas in a region above the shield; and

etching the photomask with ions and neutral species passing through the shield.

19. The method of claim 18, wherein the step of providing a predetermined gas flow pattern further comprises:

providing the deflector plate assembly with a first plate disposed below the at least one inlet, the first plate comprising an aperture; and

directing a gas flow through the aperture towards the shield.

20. The method of claim 19, wherein the step of providing a predetermined gas flow pattern further comprises:

providing the deflector plate assembly with a second plate disposed above the first plate, the second plate having a downwardly protruding portion substantially aligned with the aperture of the first plate;

providing a gas flow in a lateral direction toward the downwardly protruding portion; and

directing the gas flow through the aperture towards the shield.

21. The method of claim 18, further comprising:

controlling a distribution of ions and neutral species passing through the shield by configuring the shield into two zones with at least one characteristic different from each other, the at least one characteristic being one of material or potential bias.

22. A method of etching a photomask in a process chamber, comprising:

providing a shield above a support pedestal inside the chamber for controlling ions and neutral species passing through the shield;

introducing a process gas into the process chamber through at least one inlet at a first flow velocity;

providing a deflector plate assembly above the shield, the deflector plate assembly configured to provide a predetermined gas flow pattern between the gas inlet and the shield;

placing a photomask on the support pedestal;

forming a plasma from the process gas;

etching a first photomask at the first flow velocity;

obtaining an etch rate profile based on the etched first substrate;

adjusting the process gas through the at least one inlet to a second flow velocity based on the etch rate profile; and

etching a second photomask at the second flow velocity.

23. An apparatus for plasma etching, comprising:

a process chamber;

a substrate support pedestal disposed in the process chamber;

an RF power source for forming a plasma within the chamber;

at least one gas inlet for providing a gas flow into the chamber; and

a deflector plate assembly disposed above the substrate support pedestal and within a plasma forming region of the chamber, the deflector plate assembly configured to control radial to vertical components of a gas flow pattern between the gas inlet and the substrate support pedestal in response to changes in gas velocity.

24. The apparatus of claim 23, wherein the at least one gas inlet is disposed in a sidewall of the process chamber for producing a radial gas flow.

25. The apparatus of claim 23, wherein the deflector plate assembly comprises a first plate having an aperture.

26. The apparatus of claim 25, wherein the aperture is located in a central region of the first plate.