Semiconductor device and method of manufacture
In a wet etching process to pattern a metal layer such as a p-metal work function layer over a dielectric layer such as a high-k gate dielectric layer, a selectivity of the wet etching solution between the metal layer and the dielectric layer is increased utilizing an inhibitor. The inhibitor includes such inhibitors as a phosphoric acid, a carboxylic acid, an amino acid, or a hydroxyl group.
1. A method of manufacturing a semiconductor device, the method comprising:
forming a p-metal work function layer over a dielectric layer; and
applying a wet etching solution to the p-metal work function layer to remove a portion of the p-metal work function layer, wherein applying the wet etching solution forms a protective layer on an exposed surface of the dielectric layer after the portion of the p-metal work function layer has been removed, the wet etching solution comprising:
a metal etchant;
an inhibitor for the dielectric layer; and
a solvent.
2. The method of claim 1 , wherein the dielectric layer is hafnium oxide.
3. The method of claim 1 , wherein the inhibitor is a phosphoric acid.
4. The method of claim 1 , wherein the inhibitor is a carboxylic acid.
5. The method of claim 1 , wherein the inhibitor is an amino acid.
6. The method of claim 1 , wherein the inhibitor comprises a hydroxyl group.
7. The method of claim 1 , further comprising removing the protective layer.
8. A method of manufacturing a semiconductor device, the method comprising:
depositing a first p-work function layer onto a high-k dielectric layer; and
etching the first p-work function layer with a wet etching solution to expose a first portion of the high-k dielectric layer, wherein the wet etching solution comprises an inhibitor for the high-k dielectric layer, wherein the high-k dielectric layer reacts with the wet etching solution to form a protective layer on the high-k dielectric layer.
9. The method of claim 8 , wherein the protective layer comprises phosphorous, nitrogen, or carbon.
10. The method of claim 8 , wherein the wet etching solution further comprises:
a solvent;
a first metal etchant; and
an oxidizer.
11. The method of claim 8 , wherein the inhibitor comprises one or more of a phosphoric acid, a carboxylic acid, or an amino acid.
12. The method of claim 8 , wherein the protective layer forms a hydrophobic surface.
13. The method of claim 8 , wherein the high-k dielectric layer comprises hafnium oxide and the first p-work function layer comprises titanium nitride.
14. The method of claim 13 , wherein a selectivity of the wet etching solution between the titanium nitride and the high-k dielectric layer is at least 100:1.
15. A method of manufacturing a semiconductor device, the method comprising:
dispensing an etching solution over a p-metal work function material, the p-metal work function material being on a dielectric layer, wherein dispensing the etching solution etches the p-metal work function material to expose a portion of the dielectric layer, the etching solution forming a protective layer on the portion of the dielectric layer, the etching solution comprising:
a solvent;
a first metal etchant;
an oxidizer; and
an inhibitor comprising one or more of a phosphoric acid, a carboxylic acid, or an amino acid, the inhibitor being for the dielectric layer.
16. The method of claim 15 , wherein the inhibitor comprises di-(2-ethylhexyl)phosphoric acid.
17. The method of claim 15 , wherein the inhibitor comprises the carboxylic acid.
18. The method of claim 15 , wherein the inhibitor comprises glycine.
19. The method of claim 15 , wherein the inhibitor has a concentration of less than about 5%-volume.
20. The method of claim 15 , wherein the etching solution has a selectivity between titanium nitride and hafnium oxide of at least 100.