Contact etchback in room temperature ionic liquid

Patent metadata

Field	Value
Publication number	US-11145544-B2
Application number	US-201916407951-A
Country	US
Kind code	B2
Filing date	May 9, 2019
Priority date	Oct 30, 2018
Publication date	Oct 12, 2021
Grant date	Oct 12, 2021

Abstract

The present disclosure provides an integrated circuit with an interconnect structure and a method for forming the integrated circuit. In one embodiment, a method of the present disclosure includes receiving a workpiece that includes a first recess in a dielectric layer over the workpiece, depositing a contact fill in the first recess and over the dielectric layer to form a contact feature, planarizing a top surface of the workpiece to remove the contact fill over the dielectric layer, depositing an interlayer dielectric layer over the planarized top surface of the workpiece, forming a second recess in the interlayer dielectric layer to expose the contact fill in the dielectric layer, recessing the contact fill by soaking the workpiece in a room temperature ionic liquid, and depositing a conductive layer over the recessed contact fill. The material forming the contact fill is soluble in the room temperature ionic liquid.

First claim

What is claimed is:

1. A method of forming a low resistance contact in an integrated circuit device, the method comprising:
receiving a workpiece that includes a first recess in a dielectric layer over the workpiece;
depositing a contact fill in the first recess and over the dielectric layer to form a contact feature;
planarizing a top surface of the workpiece to remove the contact fill over the dielectric layer;
depositing an interlayer dielectric layer over the planarized top surface of the workpiece;
forming a second recess in the interlayer dielectric layer to expose the contact fill in the dielectric layer;
recessing the contact fill using a room temperature ionic liquid and an oxidizer; and
depositing a conductive layer over the recessed contact fill.

2. The method of claim 1 , wherein the depositing of the contact fill is performed using atomic layer deposition (ALD).

3. The method of claim 1 , wherein the contact fill comprises Ru, Pt, Au, Co, W, Al, Ta, TaN, Ti, Ni, NiPt, Cu, or a combination thereof.

4. The method of claim 1 , wherein the room temperature ionic liquid comprises imidazolium, pyridinium, pyrrolidinium, phosphonium, ammonium, sulfonium, or a combination thereof.

5. The method of claim 1 , wherein the room temperature ionic liquid comprises alkylsulfate, tosylate, methanesulfonate, bis(trifluoromethyl-sulfony) imide, hexafluoro phosphate, tetrafluoro borate, halide, or a combination thereof.

6. The method of claim 1 ,
wherein the contact fill comprises ruthenium,
wherein the recessing of the contact fill does not form ruthenium (VIII) oxide (RuO 4 ).

7. A method of recessing a contact on an integrated circuit device, the method comprising:
receiving a workpiece that includes a contact exposed in a bottom surface of a recess in an interlayer dielectric layer over the workpiece; and
recessing the contact using a room temperature ionic liquid and an oxidizer, wherein the recessing comprises:
oxidizing a top surface of the contact with the oxidizer, and
after oxidizing the top surface of the contact with the oxidizer, rinsing the top surface of the contact with the room temperature ionic liquid to remove residues of the oxidizer.

8. The method of claim 7 , wherein the room temperature ionic liquid comprises:
a cation selected from a group consisting of imidazolium, pyridinium, pyrrolidinium, phosphonium, ammonium, sulfonium; and
an anion selected from a group consisting of alkylsulfate, tosylate, methanesulfonate, bis(trifluoromethyl-sulfony) imide, hexafluoro phosphate, tetrafluoro borate, halide.

9. The method of claim 7 , wherein the recessing further comprises use of a ligand coordinatable with an ionic form of a material forming the contact.

10. The method of claim 9 , wherein the material comprises Ru, Pt, Au, Co, W, Al, Ta, TaN, Ti, Ni, NiPt, Cu, or a combination thereof.

11. A method of forming a low resistance contact in an integrated circuit device, the method comprising:
receiving a workpiece that includes a contact exposed in a bottom surface of a recess in an interlayer dielectric layer over the workpiece, wherein the contact is electrically coupled to a gate structure or a source/drain feature of the integrated circuit device;
recessing a contact fill of the contact by soaking the workpiece in a room temperature ionic liquid, wherein the contact fill is soluble in the room temperature ionic liquid; and
depositing a conductive layer over the recessed contact fill of the contact.

12. The method of claim 11 , wherein the contact fill of the contact comprises Ru, Pt, Au, Co, W, Al, Ta, TaN, Ti, Ni, NiPt, Cu, or a combination thereof.

13. The method of claim 11 ,
wherein the contact fill of the contact comprises ruthenium,
wherein the recessing of the contact fill of the contact does not form ruthenium (VIII) oxide (RuO 4 ).

14. The method of claim 11 , wherein the room temperature ionic liquid comprises:
a cation selected from a group consisting of imidazolium, pyridinium, pyrrolidinium, phosphonium, ammonium, sulfonium; and
an anion selected from a group consisting of alkylsulfate, tosylate, methanesulfonate, bis(trifluoromethyl-sulfony) imide, hexafluoro phosphate, tetrafluoro borate, halide.

15. The method of claim 11 , wherein the room temperature ionic liquid further comprises a ligand coordinatable with an ionic form of material forming the contact fill.

16. The method of claim 15 , wherein the ligand comprises bipyridine or benzotriazole.

17. The method of claim 7 , wherein the recessing is performed at a temperature between about 5° C. and about 100° C.

18. The method of claim 7 ,
wherein the contact comprises ruthenium,
wherein the recessing of the contact does not form ruthenium (VIII) oxide (RuO 4 ).

19. The method of claim 7 , wherein the oxidizer comprises ceric ammonium nitrate (CeAN or CAN), hydrogen peroxide, periodic acid, fluorine, bromine, chlorine, iodine, Fe(C 5 H 5 ) 2 (ferrocene), benzoquinone (1,4-benzoquinone), catechol (1,2-benzoquinone), or 1,4-napthoquinone.

20. The method of claim 1 , wherein the room temperature ionic liquid comprises 1-butyl-3 methyl imidazolium (BMI) as a cation and hexafluorophosphate (PF 6 ) as an anion.

Assignees

• Taiwan Semiconductor Mfg Co Ltd

Inventors

• Kelly Andrew Joseph

Classifications

• H10P14/43

  Chemical deposition, e.g. chemical vapour deposition [CVD] · CPC title

• H10W20/081

  by forming openings in the dielectric parts · CPC title

• H10W20/062

  by smoothing of conductive parts, e.g. by planarisation · CPC title

• H10W20/056 Primary

  by filling conductive material into holes, grooves or trenches · CPC title

• H10W20/033

  in openings in dielectrics · CPC title