Method and process for forming a self-aligned silicide contact
View Patent ↗The present invention provides a method for forming a self-aligned Ni alloy silicide contact. The method of the present invention begins by first depositing a conductive Ni alloy with Pt and optionally at least one of the following metals Pd, Rh, Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, W or Re over an entire semiconductor structure which includes at least one gate stack region. An oxygen diffusion barrier comprising, for example, Ti, TiN or W is deposited over the structure to prevent oxidation of the metals. An annealing step is then employed to cause formation of a NiSi, PtSi contact in regions in which the metals are in contact with silicon. The metal that is in direct contact with insulating material such as SiO 2 and Si 3 N 4 is not converted into a metal alloy silicide contact during the annealing step A. selective etching step is then performed to remove unreacted metal from the sidewalls of the spacers and trench isolation regions.
1. A method of forming a self-aligned metal contact comprising the steps of:
depositing a blanket layer of Ni with Pt on a surface of a structure including at least one gate region, wherein said Ni is present in a concentration from about 80 to about 95 atomic percent;
forming an oxygen diffusion barrier layer on a surface of the blanket layer;
heating the structure including the blanket layer to a temperature from about 300° C. to about 550° C. by raising the temperature from an ambient temperature at a ramp rate from about 1° C./sec to about 35° C./sec, holding the temperature for about 1 to about 60 seconds in an inert atmosphere containing less than about 1 ppm oxygen, and lowering the temperature below 100° C. within a time period from about 10 to about 600 seconds thereby forming a NiSi, PtSi contact on portions of the structure comprising silicon; and
etching the structure after heating, said etching removes unreacted NiPt selective to the contact and comprises providing a bath comprising an oxidizing agent, a complexing agent and a solvent; holding the bath at a temperature in a range from about 30° C. to about 80° C. for at least 15 minutes; contacting the structure with said bath; holding said bath at a temperature in a range from about 30° C. to about 80° C. for about 10 to about 45 minutes; removing said structure from said bath; and rinsing said structure to remove traces of said bath from said structure and drying the same.
2. The method of claim 1 wherein said blanket layer of Ni with Pt is formed by depositing a mixture containing Ni and Pt or by first depositing a Ni layer and then incorporating Pt therein.
3. The method of claim 2 wherein said Pt is incorporated by gas phase doping or ion implantation.
4. The method of claim 1 wherein said blanket layer of Ni with Pt further comprises another metal selected from the group consisting of Pd, Rh, Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, W, Re and combinations thereof.
5. The method of claim 4 wherein said another metal is Re.
6. The method of claim 1 wherein said blanket layer comprises from about 90 to about 95 atomic % Ni.
7. The method of claim 4 wherein said another metal is present in an amount up to about 50 atomic %.
8. The method of claim 7 wherein said another metal is present in an amount from about 0.1 to about 20 atomic %.
9. The method of claim 1 wherein said at least one gate region comprises a gate dielectric, a gate conductor and a spacer located on sidewalls of at least the gate conductor.
10. The method of claim 1 wherein said at least one gate region is formed atop a semiconductor substrate which includes trench isolation regions.
11. The method of claim 10 wherein said semiconductor substrate is a Si-containing material.
12. The method of claim 1 wherein said at least one gate region comprises a polySi gate conductor.
13. The method of claim 1 wherein said at least one gate region is an NFET or a PFET.
14. The method of claim 1 wherein said oxygen diffusion barrier layer comprises one of Ti, TiN, W, WN, Ta or TaN.
15. The method of claim 1 wherein said raising is performed to a temperature from about 300° C. to about 550° C. at a ramp rate from about 1° C./sec to about 35° C./sec.
16. The method of claim 1 wherein said holding is performed for a time period from about 1 to about 60 seconds.
17. The method of claim 1 wherein said lowering the temperature is performed at a temperature below 100° C. within a time period from about 10 to about 600 seconds.
18. The method of claim 1 wherein said holding temperature is from about 35° C. to about 45° C. and said holding time is at least 30 minutes.
19. The method of claim 1 wherein oxidizing agent, said complexing agent and said solvent are present in a molar ratio from about 1:10:200 to about 1:1:5.
20. The method of claim 1 wherein said oxidizing agent comprises nitric acid, hydrogen peroxide, potassium permanganate, persulfate (sodium, ammonia or potassium), eerie ammonium nitrate or potassium monopersulfate.
21. The method of claim 20 wherein said oxidizing agent is nitric acid.
22. The method of claim 1 wherein said complexing agent is chloride ion supplied as sodium chloride and hydrochloric acid, sodium iodide, potassium iodide, sodium bromide or potassium bromide.
23. The method of claim 22 wherein said complexing agent is hydrochloric acid.
24. The method of claim 1 wherein said solvent is a polar solvent or a nonpolar solvent.
25. The method of claim 1 wherein said solvent is water.
26. The method of claim 1 wherein said oxidizing agent is nitric acid, said complexing agent is hydrochloric acid and said solvent is water.
27. The method of claim 1 wherein said holding said bath is performed at a temperature from about 35° C. to about 45° C. and said time is from about 15 to about 45 minutes.