Method of semiconductor manufacturing for small features

1. A method comprising:

forming a first hard mask layer over a substrate, the first hard mask layer comprising a carbon-containing material;

forming a second hard mask layer over the first hard mask layer;

forming a third hard mask layer over the second hard mask layer, the third hard mask layer comprising a carbon-containing material;

etching the third hard mask layer to form a third hard mask comprising a tapered opening having an upper first opening with sides converging to a lower second opening;

etching the second hard mask using the third hard mask to form a second hard mask comprising an opening substantially corresponding to the lower second opening of the third hard mask;

etching the first hard mask layer to form a first hard mask comprising an opening substantially corresponding to the opening in the second hard mask; and

etching the substrate using the first hard mask.

2. The method according to claim 1 , comprising providing an etch stop layer, having greater etch selectivity than that of the second hard mask layer between the first and second hard mask layers.

3. The method according to claim 2 , comprising:

forming the third hard mask layer at a first thickness; and

forming the second hard mask layer at a second thickness less than the first thickness.

4. The method according to claim 3 , comprising forming the second hard mask layer at a thickness of about 5 nm to about 80 nm.

5. The method according to claim 4 , comprising forming the second hard mask layer at a thickness of about 10 nm to about 20 nm.

6. The method according to claim 4 , comprising forming the third hard mask layer at a thickness of about 100 nm to about 500 nm.

7. The method according to claim 6 , comprising forming the first hard mask layer at a thickness of about 100 nm to about 500 nm.

8. The method according to claim 1 , comprising:

forming the first hard mask layer from amorphous carbon; and

forming the third mask layer from amorphous carbon, diamond like carbon, tetrahedral amorphous carbon, or graphite.

9. The method according to claim 8 , comprising forming the second hard mask layer from a silicon-containing material or a high-K oxide.

10. The method according to claim 9 , comprising:

forming the second hard mask layer from a silicon oxide; and

forming the etch stop layer from a silicon nitride or a silicon oxynitride.

11. The method according to claim 1 , comprising etching to form the third hard mask with the sides of the tapered opening converging to the lower second opening having a dimension less than or equal to about 60 nm.

12. The method according to claim 3 , comprising:

forming an antireflective coating (ARC) on the third hard mask layer;

etching the ARC to form an ARC mask comprising a tapered opening having an upper first opening with sides converging to a lower second opening;

etching to form the third hard mask with the upper opening therein substantially corresponding to the lower second opening of the ARC mask;

removing the third hard mask; and

sequentially etching the etch stop layer, first hard mask, and substrate.

13. A method of fabricating a semiconductor chip, the method comprising:

forming an amorphous carbon first hard mask layer over a substrate;

forming a nitride etch stop layer over the first hard mask layer;

forming an oxide second hard mask layer at a first thickness over the nitride etch stop layer;

forming a carbon-containing third hard mask layer, at a second thickness greater than the first thickness, over the second hard mask layer;

etching the third hard mask layer to form a third hard mask comprising a tapered opening having an upper first opening with sides converging to a lower second opening;

etching the second hard mask using the third hard mask and stopping on the etch stop layer to form a second hard mask comprising an opening substantially corresponding to the lower second opening of the third hard mask;

removing the third hard mask leaving the second hard mask; and

sequentially etching the etch stop layer, first hard mask layer, and substrate.

14. The method according to claim 13 , comprising:

forming the third hard mask layer at a thickness of about 100 nm to about 500 nm; and

forming the second hard mask at a thickness of about 5 nm to about 80 nm.

15. The method according to claim 14 , comprising forming the second mask layer at a thickness of about 10 nm to about 20 nm.

16. A semiconductor chip formed by the method according to claim 13 .

17. A method of fabricating a semiconductor device, the method comprising:

forming a first hard mask layer over a substrate;

forming a multilayer hard mask layer over the first hard mask layer, the multilayer hard mask layer comprising sublayers;

forming an antireflective coating (ARC) on the multilayer hard mask layer;

etching the ARC to form a first tapered opening having sides converging from a first top opening to a first bottom opening at a top surface of the multilayer hard mask layer;

etching the multilayer hard mask layer to form a second opening having an upper third opening, corresponding to the first bottom opening with sides converging to a lower fourth opening and a third opening with substantially parallel sides and an opening substantially corresponding to the lower fourth opening of the second opening;

etching through the third opening to form a corresponding opening in the first hard mask layer; and

etching the substrate through the corresponding opening in the first hard mask layer.

18. The method according to claim 17 , comprising:

forming the first hard mask layer from amorphous carbon;

forming the second opening in a carbon-containing sub-layer having a first thickness; and

forming the third opening in an oxide sub-layer having a second thickness of about 5 nm to about 80 nm, the second thickness being less than the first thickness.

19. A semiconductor device produced by the method according to claim 17 .