Cleaning solutions and etchants and methods for using same

• US 20050143270A1
• Filed: 10/27/2004
• Published: 06/30/2005
• Est. Priority Date: 10/28/2003
• Status: Active Grant

• Current Assignee: Sachem, Inc.
• Original Assignee: Sachem, Inc.
• Inventors: Collins, Sian, Wojtczak, William A., Dewulf, Dean
• Granted Patent: US 7,192,910 B2
• Time in Patent Office: Days
• US Class Current: 510/175
• CPC Class Codes: C11D 11/0047 Electronic devices, e.g. PCBs or semiconductors
• CPC Class Codes: C11D 2111/22 Electronic devices, e.g. PCBs or semiconductors
• CPC Class Codes: C11D 7/3218 Alkanolamines or alkanolimines
• CPC Class Codes: C11D 7/3227 Ethers thereof
• CPC Class Codes: C11D 7/34 containing sulfur
• CPC Class Codes: C11D 7/36 containing phosphorus
• CPC Class Codes: C11D 7/5004 Organic solvents
• CPC Class Codes: H01L 21/02063 the processing being the formation of vias or contact holes
• CPC Class Codes: H01L 21/02071 the processing being a delineation, e.g. RIE, of conductive layers
• CPC Class Codes: H01L 21/31111 by chemical means
• CPC Class Codes: H01L 21/76814 post-treatment or after-treatment, e.g. cleaning or removal of oxides on underlying conductors

Abstract

Composition for cleaning or etching a semiconductor substrate and method for using the same. The composition may include a fluorine-containing compound as an active agent such as a quaternary ammonium fluoride, a quaternary phosphonium fluoride, sulfonium fluoride, more generally an -onium fluoride or “multi” quaternary-onium fluoride that includes two or more quaternary-onium groups linked together by one or more carbon-containing groups. The composition may further include a pH adjusting acid such as a mineral acid, carboxylic acid, dicarboxylic acid, sulfonic acid, or combination thereof to give a pH of about 2 to 9. The composition can be anhydrous and may further include an organic solvent such as an alcohol, amide, ether, or combination thereof. The composition are useful for obtaining improved etch rate, etch selectivity, etch uniformity and cleaning criteria on a variety of substrates.

Claims

1. A composition useful for cleaning or etching a substrate, comprising:

a salt containing fluoride and a phosphonium cation;

an acid;

an organic solvent;

water in an amount less than about 5% of the composition by weight; and

a pH of between about 2 and about 9.

2. The composition of claim 1, wherein the salt is tetrabutyl phosphonium fluoride.

3. The composition of claim 1, wherein the salt makes up between about 1% and about 10% by weight of the composition.

4. The composition of claim 1, wherein the organic solvent is an alcohol.

5. The composition of claim 1, wherein the organic solvent is a glyme.

6. The composition of claim 1, wherein the water makes up between about 0.5% and about 4% of the composition by weight.

7. The composition of claim 1, wherein the pH is between about 2 and about 4.

8. The composition of claim 1, further comprising a second salt selected from the group consisting of a quaternary ammonium salt, a sulfonium salt, and a phosphonium salt.

9. The composition of claim 1, wherein the composition has a free metal ion content of less than about 10 PPB.

10. The composition of claim 1, wherein the composition is capable of etching a DARC layer at a rate greater than it etches a doped oxide layer.

11. The composition of claim 1, wherein the composition is capable of etching an undoped oxide layer at a rate greater than it etches a doped oxide layer.

12. The composition of claim 1, wherein the composition is capable of non-selectively etching a doped oxide layer and an undoped oxide layer.

13. The composition of claim 1, wherein the salt is tetrabutyl phosphonium fluoride, the solvent is a glyme, the water is present in an amount less than about 3%, and the pH is between about 2.5 and about 4.

14. The composition of claim 1, wherein the salt is tetrabutyl phosphonium fluoride and further comprising tetrabutyl phosphonium benzoate.

15. A composition for cleaning or etching a semiconductor substrate, comprising:

a salt containing fluoride and a quaternary ammonium cation comprising at least one alkanol or alkoxy group;

an acid;

an organic solvent;

water in an amount that is less than about 5% of the weight of the formulation; and

a pH of between about 2 and about 9.

16. A composition for cleaning or etching a substrate, comprising:

a salt containing fluoride and a sulfonium cation;

an acid;

an organic solvent;

less than about 5% water; and

a pH of between about 2 and about 9.

17. A composition for cleaning or etching a substrate, comprising:

a salt containing fluoride and a cation comprising two or more quaternary ammonium groups linked together by one or more carbon-containing groups;

an acid;

an organic solvent;

less than about 5% water; and

a pH of between about 2 and about 9.

18. A composition for cleaning or etching a substrate, comprising:

between about 1.5% and about 3.5% by weight of tetramethyl ammonium fluoride;

less than about 1% by weight of an acid;

greater than about 90% by weight of a solvent comprising an alcohol;

less than about 4% by weight of water; and

a pH of between about 3 and about 4.

19. A method for patterning a semiconductor substrate, comprising:

depositing an antireflective coating onto a substrate; and

selectively removing at least a portion of the antireflective coating by contacting it with a composition comprising;

a salt containing fluoride and a phosphonium cation;

an acid;

an organic solvent;

less than about 5% water; and

a pH of between about 2 and about 9.

20. The method of claim 19, wherein the substrate comprises amorphous carbon and BPSG, and wherein the composition etches the antireflective coating at a rate greater than that at which it removes the amorphous carbon or the BPSG.

21. A method of etching and cleaning a semiconductor substrate, comprising:

(a) etching a dielectric to expose a contact material on the substrate, thereby forming a residue;

(b) contacting the contact material with a cleaning formulation to remove the residue, the cleaning formulation comprising;

a salt containing fluoride and a phosphonium cation;

an acid;

an organic solvent;

less than about 5% water; and

a pH of between about 2 and about 9.

22. The method of claim 21, wherein the contact material is a pre-metal contact selected from the group consisting of doped silicon, polysilicon, and silicide.

23. The method of claim 21, wherein the contact material is a metal.

24. A method of etching and cleaning a semiconductor substrate, comprising:

(a) etching a metal to form an interconnect metal line, thereby forming a residue;

(b) contacting the metal with a cleaning formulation to remove the residue, the cleaning formulation comprising;

a salt containing fluoride and a phosphonium cation;

an acid;

an organic solvent;

less than about 5% water; and

a pH of between about 2 and about 9.