Method of wet etching an inorganic antireflection layer
View Patent ↗The invention relates to a method of manufacturing a semiconductor device, comprising the provision of a substrate with a layer of silicon thereon, an inorganic anti-reflective layer applied to the layer of silicon, and a resist mask applied to the inorganic anti-reflective layer, which method comprises the steps of: patterning the inorganic anti-reflective layer by means of the resist mask, patterning the layer of silicon, removing the resist mask, and removing the inorganic anti-reflective layer by means of etching with an aqueous solution comprising hydrofluoric acid in a low concentration, which aqueous solution is applied at a high temperature.
1. A method of manufacturing a semiconductor device, comprising the provision of a substrate with a layer of silicon thereon, an inorganic anti-reflective layer applied to the layer of silicon, and a resist mask applied to the inorganic anti-reflective layer, which method comprises the steps of:
patterning the inorganic anti-reflective layer by means of the resist mask,
patterning the layer of silicon,
removing the resist mask, and
removing the inorganic anti-reflective layer by means of etching with an aqueous solution comprising hydrofluoric acid:
wherein the aqueous solution is treated so as to keep the layer of silicon in a non-oxidized state during etching the inorganic anti-reflective layer.
2. A method as claimed in claim 1 , wherein the inorganic anti-reflective layer is applied as a layer of silicon nitride or a layer of silicon oxynitride.
3. A method as claimed in claim 2 , wherein a layer of silicon-rich silicon nitride is applied as the layer of silicon nitride.
4. A method as claimed in claim 2 , wherein a layer of silicon-rich silicon oxynitride is applied as the layer of silicon oxynitride.
5. A method as claimed in claim 1 , wherein the hydrofluoric acid is applied in a concentration in the range from about 0.001 to 0.1 M.
6. A method as claimed in claim 1 , wherein the aqueous solution is applied at a temperature in the range from about 30° C. to 130° C., the aqueous solution being applied under elevated pressure to reach a temperature above 100° C.
7. A method as claimed in claim 6 , wherein the aqueous solution is applied at a temperature in the range from 100° C. to 130° C.
8. A method as claimed in claim 1 , wherein dissolved oxygen is removed from the aqueous solution by evacuating the aqueous solution.
9. A method as claimed in claim 1 , wherein dissolved oxygen is removed from the aqueous solution by exchanging it for an inert gas.
10. A method as claimed in claim 1 , wherein a reducing agent is added to the aqueous solution.
11. The method of claim 10 , wherein the reducing agent is H 2 .
12. The method of claim 11 , further comprising providing the H 2 to the aqueous solution by bubbling.
13. A method as claimed in claim 1 , wherein the substrate is applied with an uppermost layer of a dielectric material, with respect to which the inorganic anti-reflective layer can be selectively etched.
14. A method as claimed in claim 1 , wherein a layer of polycrystalline silicon or a layer of amorphous silicon is applied as the layer of silicon.
15. A method as claimed in claim 1 , wherein the resist mask is removed before the layer of silicon is patterned.
16. A method as claimed in claim 1 , wherein the inorganic anti-reflective layer is etched by means of a single-wafer process.
17. The method of claim 1 , wherein the aqueous solution further comprises a surfactant.
18. The method of claim 1 , wherein the aqueous solution further comprises a pH modifier.