Methods of thin film process

1. A method for forming a semiconductor structure, comprising:

forming a plurality of features across a surface of a substrate, at least one space being between two adjacent features;

forming a first dielectric layer on the features and within the at least one space, wherein the first dielectric layer forms a narrower gap above the opening of the at least one space than a lateral gap deeper within the at least one space;

interacting a portion of the first dielectric layer with a reactant, the reactant derived from a first precursor and a second precursor, to form a first solid product, wherein the solid product comprises material from both the reactant and the first dielectric layer;

decomposing the first solid product to substantially remove the portion of the first dielectric layer; and

forming a second dielectric layer to substantially fill the at least one space.

2. The method of claim 1 , wherein forming a plurality of features comprises forming at least a plurality of trenches, conductive lines, openings and transistor gates.

3. The method of claim 1 , wherein forming the first dielectric layer comprises forming a silicon oxide layer.

4. The method of claim 1 , wherein interacting the portion of the first dielectric layer with a reactant comprises:

ionizing the first precursor and the second precursor; and

interacting the ionized first precursor and the ionized second precursor with the portion of the first dielectric layer.

5. The method of claim 1 , wherein the first precursor is ammonia (NH 3 ) and the second precursor is nitrogen trifluoride (NF 3 ).

6. The method of claim 1 , wherein interacting the portion of the first dielectric layer with the reactant comprises:

interacting the portion of the first dielectric layer with the first precursor and the second precursor.

7. The method of claim 1 , wherein the first precursor is ammonia (NH 3 ) and the second precursor is hydrogen fluoride (HF).

8. The method of claim 1 , wherein forming the first dielectric layer comprises forming a silicon nitride layer.

9. The method of claim 8 , wherein interacting the portion of the first dielectric layer with a reactant comprises:

ionizing the first precursor and the second precursor; and

interacting the portion of the silicon nitride layer with the ionized first precursor and the ionized second precursor.

10. The method of claim 9 , wherein the first precursor is hydrogen (H 2 ) and the second precursor is nitrogen trifluoride (NF 3 ).

11. The method of claim 1 , wherein decomposing the first solid product comprises thermally treating the first solid product to substantially sublimate the first solid product.

12. The method of claim 1 , wherein decomposing the first solid product comprises dissolving the product in a liquid solution.

13. The method of claim 12 , wherein the liquid solution comprises water or a polar solvent.

14. The method of claim 1 further comprising forming a liner under the first dielectric layer, wherein an etch selectivity of the first dielectric layer to the liner is about 5:1 or more.

15. The method of claim 14 further comprising:

interacting a portion of the liner with a reactant derived from a third precursor and a fourth precursor to generate a second solid product; and

decomposing the second solid product to remove the portion of the liner.

16. The method of claim 1 further comprising:

interacting another portion of the first dielectric layer with a reactant derived from a third precursor and a fourth precursor to generate a second solid product; and

decomposing the second solid product to remove the another portion of the first dielectric layer.

17. The method of claim 1 , wherein forming the first dielectric layer on the features and within the at least one space has a process pressure of about 600 Torr or more.

18. The method of claim 1 , wherein decomposing the first solid product forms an angle between slanted sidewalls of the removed first dielectric layer and a bottom of the removed first dielectric layer about 87° or less.

19. A method of depositing a dielectric material in a semiconductor structure having a bottom and sidewalls, the method comprising:

forming a first dielectric layer on the bottom and sidewalls of the structure, wherein the layer partially fills the structure and forms a narrower gap above the opening of the structure than a lateral gap deeper within the structure;

interacting a portion of the first dielectric layer with a reactant derived from a first precursor and a second precursor to form a first solid product, wherein the solid product comprises material from both the reactant and the first dielectric layer;

thermally treating the first solid product to substantially sublimate the first solid product and form a slanted opening in the structure; and

forming a second dielectric layer to substantially fill the spaces.

20. The method of claim 19 , wherein the structure is a gap, and a first angle formed between the bottom and one of the sidewalls of the gap ranges from about 89° to about 91°, and wherein a second angle between a sidewall and bottom of the slanted opening is less than 87°.

21. The method of claim 20 , wherein interacting the portion of the first dielectric layer with a reactant comprises:

forming a plasma from the first precursor and the second precursor; and

interacting the plasma with the portion of the first dielectric layer.

22. The method of claim 21 , wherein the first precursor is ammonia (NH 3 ) and the second precursor is nitrogen trifluoride (NF 3 ) or hydrogen fluoride (HF).

23. The method of claim 21 , wherein interacting the portion of the first dielectric layer with a reactant comprises:

introducing the first precursor and the second precursor into an etch chamber; and

interacting the portion of the first dielectric layer with the first precursor and the second precursor.

24. The method of claim 19 , wherein forming the first dielectric layer comprises forming a silicon nitride layer.

25. The method of claim 24 , wherein interacting the portion of the first dielectric layer with a reactant comprises:

ionizing the second precursor;

introducing the first precursor and the ionized second precursor into an etch chamber; and

interacting the portion of the silicon nitride layer with the first precursor and the ionized second precursor.