Method for forming and using mask

1. A method of forming a semiconductor device, the method comprising:

patterning a photoresist layer on a mask layer;

performing an oxygen plasma treatment on the photoresist layer, the oxygen plasma treatment converting the photoresist layer to a treated photoresist layer by oxidizing an exposed surface of the photoresist layer;

after the performing the oxygen plasma treatment patterning the mask layer using the treated photoresist layer as a mask, wherein during an etching of the mask layer the treated photoresist layer is an oxidized organic material; and

patterning a target layer using the patterned mask layer as a mask.

2. The method of claim 1 , wherein the oxygen plasma treatment is performed at a temperature less than 200° C.

3. The method of claim 1 , wherein the oxygen plasma treatment is performed for a duration in a range of 1 second to 10 seconds.

4. The method of claim 1 , wherein the photoresist layer comprises carbon.

5. The method of claim 1 , further comprising performing a de-scum process on the semiconductor device after patterning the photoresist layer.

6. The method of claim 5 , wherein the de-scum process is performed before performing the oxygen plasma treatment on the photoresist layer.

7. The method of claim 5 , wherein the de-scum process is performed after performing the oxygen plasma treatment on the photoresist layer.

8. A method of forming a semiconductor device, the method comprising:

forming a film over a patterned top layer, the patterned top layer being on a mask layer, the mask layer being over a target layer, wherein openings extend through the patterned top layer to expose the mask layer, a first portion of the film over the patterned top layer has a first thickness, a second portion of the film on a bottom surface of the openings has a second thickness, and the first thickness is greater than the second thickness;

patterning the mask layer using the patterned top layer as a mask; and

using the patterned mask layer as a mask to pattern the target layer.

9. The method of claim 8 , wherein the film is silicon oxide, silicon oxycarbide, or silicon oxycarbonitride.

10. The method of claim 8 , wherein forming the film comprises a plasma enhanced atomic layer deposition process.

11. The method of claim 8 , further comprising performing a thinning process on the film before patterning the mask layer.

12. The method of claim 11 , wherein the film has a thickness in a range of 3 Å to 30 Å over a top surface of the patterned top layer before the thinning process.

13. The method of claim 11 , wherein the film has a thickness in a range of 0.1 Å to 12.5 Å over a top surface of the patterned top layer after the thinning process.

14. The method of claim 8 , wherein the mask layer comprises a film stack over the target layer and a photoresist over the film stack.

15. A method of forming a semiconductor device, the method comprising:

forming a film stack over a target layer, the target layer being on a substrate;

forming a photoresist over the film stack, the photoresist comprising a bottom layer, a middle layer over the bottom layer, and a top layer over the middle layer;

patterning the top layer, wherein the patterning the top layer forms first openings through the patterned top layer;

forming an oxide layer on exposed surfaces of the patterned top layer and over bottom surfaces of the first openings, wherein the oxide layer has a first thickness on the exposed surfaces of the patterned top layer and a second thickness over the bottom surfaces of the first openings, wherein the first thickness is greater than the second thickness;

patterning the middle layer using the patterned top layer as a mask;

patterning the bottom layer using the patterned middle layer as a mask;

patterning the film stack using the patterned bottom layer as a mask;

patterning the target layer using the patterned film stack as a mask to form second openings through the target layer; and

forming conductive features in the second openings.

16. The method of claim 15 , wherein forming the oxide layer comprises an O 2 plasma process.

17. The method of claim 15 , wherein forming the oxide layer comprises depositing an oxide film over the patterned top layer.

18. The method of claim 17 , wherein the oxide film comprises silicon and carbon.

19. The method of claim 15 , wherein the film stack comprises an anti-reflective coating, a hard mask over the anti-reflective coating, and a dielectric layer over the hard mask.

20. The method of claim 15 , further comprising forming a liner in the second openings.