METHOD FOR REDUCING LINE WIDTH ROUGHNESS WITH PLASMA PRE-ETCH TREATMENT ON PHOTORESIST

• US 20110117749A1
• Filed: 11/17/2009
• Published: 05/19/2011
• Est. Priority Date: 11/17/2009
• Status: Active Grant

• Current Assignee: Lam Research Corporation
• Original Assignee: Lam Research Corporation
• Inventors: KIM, Jonathan, SHEU, Ben-Li, SHIM, Martin
• Granted Patent: US 8,329,585 B2
• Time in Patent Office: Days
• US Class Current: 438/735
• CPC Class Codes: H01J 37/32091 the radio frequency energy being capacitively coupled to the plasma
• CPC Class Codes: H01J 37/32935 Monitoring and controlling tubes by information coming from the object and/or discharge
• CPC Class Codes: H01L 21/0338 Process specially adapted to improve the resolution of the mask

Abstract

A method for reducing line width roughness (LWR) of a feature in an etch layer below a patterned photoresist mask having mask features is provided. The method includes (a) non-etching plasma pre-etch treatment of the photoresist mask, and (b) etching of a feature in the etch layer through the pre-treated photoresist mask using an etching gas. The non-etching plasma pre-etch treatment includes (a1) providing a treatment gas containing H₂ and COS, (a2) forming a plasma from the treatment gas, and (a3) stopping the treatment gas.

Claims

1. A method for reducing line width roughness (LWR) of a feature in an etch layer below a patterned photoresist mask having mask features, the method comprising:

non-etching plasma pre-etch treatment of the photoresist mask, comprising;

providing a treatment gas containing H₂ and COS;

forming a plasma from the treatment gas;

stopping the treatment gas; and

etching a feature in the etch layer through the pre-treated photoresist mask using an etching gas.

2. The method as recited in claim 1, wherein said non-etching plasma pre-etch treatment further comprises:

curing and smoothing surfaces of the mask features using the plasma formed from the treatment gas.

3. The method as recited in claim 2, wherein said curing and smoothing includes:

reducing single and double C—

O bonds from the surfaces of the photoresist mask using H₂ component; and

depositing materials on sidewalls of the mask features using COS component.

4. The method as recited in claim 3, wherein a thickness of the deposited materials is less than 5 nm.

5. The method as recited in claim 1, wherein H₂ and COS has at least 50% of a total flow of the treatment gas.

6. The method as recited claim 4, wherein the treatment gas further contains N₂ and C₄F₈.

7. The method as recited claim 1, wherein the treatment gas essentially consists of H₂ and COS.

8. The method as recited claim 1, wherein a flow ratio of H₂ and COS is about 10:

1 to 60;

1.

9. The method as recited claim 1, wherein a flow ratio of H₂ and COS is about 20:

1 to 50;

1.

10. The method as recited claim 1, wherein said non-etching pre-etch treatment includes:

controlling a bias voltage such that the non-etching plasma pre-etch treatment does not open or substantially etch an underlying layer exposed through the mask features.

11. The method as recited claim 1, wherein said forming the plasma includes:

applying a bias voltage between 0 to 500 V.

12. The method as recited claim 1, wherein said forming the plasma includes:

applying a bias voltage between 0 to 150 V.

13. The method as recited claim 1, wherein said non-etching pre-treating substantially preserves an original aspect ratio of the mask features.

14. An apparatus for reducing line width roughness (LWR) of a feature in an etch layer below a patterned photoresist mask having mask features, said apparatus comprising:

a plasma processing chamber, comprising;

a chamber wall forming a plasma processing chamber enclosure;

a substrate support for supporting a substrate within the plasma processing chamber enclosure;

a pressure regulator for regulating the pressure in the plasma processing chamber enclosure;

at least one electrode for providing power to the plasma processing chamber enclosure for sustaining a plasma;

a gas inlet for providing gas into the plasma processing chamber enclosure; and

a gas outlet for exhausting gas from the plasma processing chamber enclosure;

a gas source in fluid connection with the gas inlet, comprising;

a photoresist mask treatment gas source; and

a feature etching gas source;

a controller controllably connected to the gas source and the at least one electrode, comprising;

at least one processor; and

computer readable media, comprising;

computer readable code for non-etching plasma pre-etch treatment of the photoresist mask, including;

computer readable code for providing a treatment gas containing H₂ and COS;

computer readable code for forming a plasma from the treatment gas; and

computer readable code for stopping the treatment gas, and

computer readable code for etching a feature in the etch layer through the pre-treated photoresist mask using an etching gas.

15. The apparatus as recited in claim 14, wherein said computer readable code for non-etching plasma pre-etch treatment further comprises:

computer readable code for controlling a bias voltage such that the non-etching plasma pre-etch treatment does not open or substantially etch an underlying layer exposed through the mask features.

16. The apparatus as recited in claim 15, wherein said bias voltage is between 0 to 500 V.

17. The apparatus as recited in claim 15, wherein said bias voltage is between 0 to 150 V.

18. The apparatus as recited in claim 14, wherein said computer readable code for non-etching plasma pre-etch treatment further comprises:

computer readable code for controlling a flow ratio of H₂ and COS to be between 10;

1 to 60;

1.

19. The apparatus as recited in claim 14, wherein said computer readable code for non-etching plasma pre-etch treatment further comprises:

computer readable code for controlling a flow ratio of H₂ and COS to be between 20;

1 to 50;

1.