Etching method of semiconductor substrate, and method of producing semiconductor device

1. An etching method comprising: at the time of processing a substrate having a first layer containing titanium nitride (TiN) and a second layer containing a transition metal,

selecting a substrate in which a surface oxygen content of the first layer is from 0.1 to 10% by mole; and an etching rate of the first layer is 200A°/min or greater and less than 300A°/min.

applying an etching liquid containing a hydrofluoric acid compound and an oxidizing agent to said substrate and thereby removing the first layer.

2. The etching method according to claim 1 , wherein the transition metal is selected from Co, Ni, Cu, Ag, Ta, Hf, W, Pt and Au.

3. The etching method according to claim 1 , wherein the hydrofluoric acid compound is a hydrofluoric acid or its salt.

4. The etching method according to claim 1 , wherein the oxidizing agent is a nitric acid or a hydrogen peroxide.

5. The etching method according to claim 1 , wherein the etching liquid further contains at least one surface uniformizing agent selected from the group consisting of a nitrogen-containing organic compound, an aromatic compound and an oxygen-containing organic compound.

6. The etching method according to claim 5 , wherein the surface uniformizing agent includes a compound represented by any one of the following formulae (I) to (IX):

wherein R 1 to R 30 each independently represent a hydrogen atom or a substituent; in this case, neighbors adjacent to each other may be linked or ring-fused to form a cyclic structure; A represents a nitrogen atom.

7. The etching method according to claim 5 , wherein the surface uniformizing agent is at least one selected from the group consisting of an alcohol compound having 2 to 15 carbon atoms and an ether compound having 2 to 15 carbon atoms.

8. The etching method according to claim 5 , wherein the surface uniformizing agent is contained in a range of from 0.01 to 10% by mass.

9. The etching method according to claim 1 , wherein the hydrofluoric acid compound is contained in a range of from 0.01 to 3% by mass.

10. The etching method according to claim 1 , wherein the oxidizing agent is contained in a range of from 0.05 to 30% by mass.

11. The etching method according to claim 1 , wherein a pH of the etching liquid is in a range of −1 or more and 5 or less.

12. The etching method according to claim 1 , wherein a thickness of the first layer is from 0.005 to 0.3 μm.

13. A method of producing a semiconductor device comprising: removing a first layer containing titanium nitride (TiN) by the etching method according to claim 1 ; and then producing the semiconductor device from the remaining substrate.

14. The etching method according to claim 1 , wherein the etching method is carried out by a single wafer etching.

15. The method of producing a semiconductor device according to claim 13 , wherein the etching method is carried out by a single wafer etching.

16. An etching liquid for processing a substrate having a first layer containing titanium nitride (TiN) and a second layer containing a transition metal and for applying to a selected substrate in which a surface oxygen content of the first layer is from 0.1 to 10% by mole, wherein the etching liquid contains a hydrofluoric acid compound and an oxidizing agent.

17. The etching liquid according to claim 16 , wherein the hydrofluoric acid compound is contained in a range of from 0.01 to 3% by mass.

18. The etching liquid according to claim 16 , wherein the oxidizing agent is contained in a range of from 0.05 to 30% by mass.

19. The etching liquid according to claim 16 , wherein a pH is from −1 to 5.

20. The etching liquid according to claim 16 , further containing at least one surface uniformizing agent selected from the group consisting of a nitrogen-containing organic compound, an aromatic compound and an oxygen-containing organic compound.