Method for forming a contact having a diffusion barrier

• US 6,284,651 B1
• Filed: 03/19/1999
• Issued: 09/04/2001
• Est. Priority Date: 02/23/1996
• Status: Expired due to Term

• Current Assignee: Micron Technology, Inc.
• Original Assignee: Micron Technology, Inc.
• Inventors: Sharan, Sujit, Nagabushnam, Varatharajan
• Primary Examiner(s): Niebling, John F.
• Assistant Examiner(s): Nguyen, Ha Tran
• Application Number:
  US09/273,118
• Time in Patent Office: 900 Days
• Field of Search: 438/532, 438/533, 438/517, 438/637-640, 438/643, 438/647, 438/649, 438/648, 438/653, 438/655, 438/657-660, 438/684
• US Class Current: 438/649
• CPC Class Codes: H01L 21/28518 the conductive layers comprising silicides H01L21/28537 takes precedence
• CPC Class Codes: H01L 21/28525 the conductive layers comprising semiconducting material H01L21/28518, H01L21/28537 take precedence
• CPC Class Codes: H01L 21/76843 formed in openings in a dielectric
• CPC Class Codes: H01L 21/76855 After-treatment introducing at least one additional element into the layer
• CPC Class Codes: H01L 21/76856 by treatment in plasmas or gaseous environments, e.g. nitriding a refractory metal liner
• CPC Class Codes: H01L 21/76877 Filling of holes, grooves or trenches, e.g. vias, with conductive material
• CPC Class Codes: H01L 23/485 consisting of layered constructions comprising conductive layers and insulating layers, e.g. planar contacts H01L23/4821, H01L23/4822, H01L23/4824, H01L23/4825 take precedence; materials H01L23/532, bond pads H01L24/02, bump connectors H01L24/10
• CPC Class Codes: H01L 23/53271 containing semiconductor material, e.g. polysilicon
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00

Abstract

Disclosed is a novel contact structure comprising an underlying layer of titanium silicide, an intermediate layer of titanium boride, and an overlying layer of polysilicon. Also disclosed is a method for forming the contact structure which comprises depositing a titanium layer in the bottom of a contact opening having oxide insulation sidewalls, forming an overlying layer of polysilicon above the titanium layer, and annealing the two layers together. The resulting contact structure is formed with fewer steps than contact structures of the prior art and without the need for additional steps to achieve uniform sidewall coverage, due to high adhesion of the overlying layer of polysilicon with oxide insulation sidewalls of the contact opening. The contact structure has low contact resistance, and provides a suitable diffusion barrier due to a high melting point.

Claims

1. A method of forming a contact structure, the method comprising:

forming a contact opening through an insulating layer, wherein the contact opening has a bottom and has a sidewall defined by the insulating layer, the bottom of the contact opening at a silicon substrate;

forming, in an atmosphere devoid of fluorine, a layer of a refractory metal on the bottom of the contact opening;

forming, in the contact opening, a layer of an electrically conductive silicon-containing material in contact with the layer of the refractory metal and the sidewall; and

heating the refractory metal and the silicon-containing material to form a structure in the contact opening comprising;

a refractory metal silicide layer located in the bottom of the contact opening;

a refractory metal boride layer located on the refractory metal silicide layer in the contact opening; and

wherein

the layer of silicon-containing material fills the remainder of the contact opening.

2. A method as recited in claim 1, wherein:

the insulating layer comprises an oxide; and

the silicon-containing material adheres to the oxide of the sidewall.

3. A method as recited in claim 1, wherein the layer of refractory metal is formed by chemical vapor deposition.

4. A method as recited in claim 1, wherein the layer of refractory metal is formed with a thickness in a range of about 200 Angstroms to about 300 Angstroms.

5. A method as recited in claim 1, wherein the layer of electrically conductive silicon-containing material is formed with a thickness in a range of about 6000 Angstroms to about 7000 Angstroms.

6. A method as recited in claim 1, wherein the silicon-containing material is doped with a range of about 1×

10²⁰ to about 5×

10²⁰ atoms of boron per cubic centimeter of silicon-containing material.

7. A method as recited in claim 1, wherein said heating comprises conducting a rapid thermal anneal in a rapid thermal processing chamber at a temperature in a range of about 800°

C. to about 950°

C.

8. A method as recited in claim 1, wherein said heating comprises heating in a tube furnace having a temperature in a range of about 800°

C. to about 900°

C. in a predominantly argon atmosphere.

9. A method as recited in claim 1, wherein the layer of electrically conductive silicon-containing material is formed from a silane precursor.

10. A method as recited in claim 9, wherein the layer of electrically conductive silicon-containing material is formed from the silane precursor in an atmosphere of B₂H₆, at a temperature in a range of about 630°

C. to about 650°

C.

11. A method as recited in claim 1, wherein the layer of electrically conductive silicon-containing material is formed from a disilane precursor.

12. A method as recited in claim 11, wherein the layer of electrically conductive silicon-containing material is formed from the disilane precursor in an atmosphere of B₂H₆, at a temperature in a range of about 550°

C. to about 570°

C.

13. A method as recited in claim 1, wherein the layer of refractory metal in the bottom of the contact opening adheres to the sidewall defined by the insulating layer.

14. A method as recited in claim 1, wherein said silicon-containing material is made electrically conductive by doping with boron.

15. A method as recited in claim 1, wherein the layer of refractory metal is formed by physical vapor deposition.

16. A method as recited in claim 15, wherein said physical vapor deposition is through a collimator.

17. A method as recited in claim 1, wherein the refractory metal is titanium.

18. A method of forming a contact structure to provide electrical communication to a semiconductor device on an in-process integrated circuit substrate, the method comprising:

forming a contact opening through an oxide layer above the semiconductor device;

forming, in an atmosphere devoid of fluorine, a layer of refractory metal in the bottom of the contact opening, the layer of refractory metal having a thickness in a range of about 200 Angstroms to about 300 Angstroms;

forming a layer of electrically conductive silicon-containing material on the layer of refractory metal, the layer of electrically conductive silicon-containing material having a thickness in a range of about 6000 to about 7000 Angstroms, the layer of electrically conductive silicon-containing material being doped in a concentration range of about 1×

10²⁰ to about 5×

10²⁰ dopant atoms per cubic centimeter of electrically conductive silicon-containing material; and

annealing the in-process integrated circuit substrate with a rapid thermal anneal in a rapid thermal processing chamber at a temperature in the range from about 800°

C. to about 950°

C.

19. A method as recited in claim 18, wherein:

the bottom of the contact opening is defined by a silicon substrate;

said annealing forms a contact structure in the contact opening comprising;

a refractory metal silicide layer in the bottom of the contact opening; and

a refractory metal boride layer on the refractory metal silicide layer; and

wherein;

the dopant atoms are boron; and

said layer of said electrically conductive silicon-containing material fills the remainder of the contact opening and has a thickness in a range of about 6000 to about 7000 Angstroms.

20. A method as recited in claim 18, wherein the layer of refractory metal in the bottom of the contact opening adheres to the oxide of a sidewall of the contact opening in the oxide layer.

21. A method as recited in claim 18, wherein the layer of refractory metal is formed by chemical vapor deposition.

22. A method as recited in claim 18, wherein the layer of refractory metal is formed by physical vapor deposition.

23. A method as recited claim 22, wherein said deposition of said refractory metal by physical vapor deposition is a deposition through a collimator.

24. A method as recited in claim 18, wherein the temperature at which the annealing the in-process integrated circuit substrate with a rapid thermal anneal in a rapid thermal processing chamber is performed is within the range from about 900°

C. to about 950°

C.

25. A method as recited in claim 18, wherein the refractory metal is titanium.

26. A method of forming a contact structure to provide electrical communication to a semiconductor device on an in-process integrated circuit substrate, the method comprising:

forming a contact opening through an insulating layer above the semiconductor device, wherein the contact has a bottom and defines a sidewall in the insulating layer, the insulating layer comprising oxide;

forming, in an atmosphere devoid of fluorine, a layer of refractory metal in the bottom of the contact opening;

forming a layer of electrically conductive silicon-containing material on the layer of refractory metal in the contact opening, the layer of electrically conductive silicon-containing material being doped, and wherein the layer of electrically conductive silicon-containing material adheres to the oxide of the sidewall in the insulating layer and is formed from a disilane precursor in an atmosphere of B₂H₆ at a temperature in a range of about 550°

C. to about 570°

C.; and

annealing the in-process integrated circuit substrate.

27. A method as recited in claim 26, wherein the layer of refractory metal is formed with a thickness in a range of about 200 Angstroms to about 300 Angstroms.

28. A method as recited in claim 26, wherein the layer of electrically conductive silicon-containing material is formed with a thickness in a range of about 6000 Angstroms to about 7000 Angstroms.

29. A method as recited in claim 26, wherein the layer of electrically conductive silicon-containing material is doped with a range of about 1×

10²⁰ to about 5×

10²⁰ atoms of boron per cubic centimeter of electrically conductive silicon-containing material.

30. A method as recited in claim 26, wherein annealing the in-process integrated circuit substrate comprises conducting a rapid thermal anneal in a rapid thermal processing chamber at a temperature in a range of about 800°

C. to about 950°

C.

31. A method as recited in claim 26, wherein annealing the in-process integrated circuit substrate comprises placing the in-process integrated circuit substrate in a furnace having a temperature in a range of about 800°

C. to about 900°

C. in a predominantly argon atmosphere.

32. A method as recited in claim 26, wherein the layer of refractory metal in the bottom of the contact opening adheres to the oxide of the sidewall in the insulating layer.

33. A method as recited in claim 26, wherein the layer of refractory metal is formed by chemical vapor deposition.

34. A method as recited in claim 26, wherein the layer of refractory metal is formed by physical vapor deposition.

35. A method as recited in claim 34, wherein said deposition of said refractory metal by physical vapor deposition is a deposition through a collimator.

36. A method as recited in claim 26, wherein the refractory metal is titanium.

37. A contact structure formation method comprising:

forming an insulator upon a silicon substrate;

forming a contact hole extending through the insulator to the silicon substrate;

forming, in an atmosphere devoid of fluorine, a refractory metal on the silicon substrate to partially fill the contact hole;

filling up the contact hole with a silicon-containing material that;

is made electrically conductive by a dopant; and

is upon the refractory metal within the contact hole;

forming by heat;

a refractory metal silicide within the silicon substrate that is both below and aligned with the contact hole; and

a compound within the contact hole including both the refractory metal and the dopant.

38. A method as recited in claim 37, wherein the refractory metal is titanium.

39. A contact structure formation method comprising:

forming an insulator upon a silicon substrate;

forming a contact hole extending through the insulator to the silicon substrate;

forming in an atmosphere devoid of fluorine;

a refractory metal silicide within the silicon substrate and both below and aligned with the contact hole;

a silicon-containing material made electrically conductive by a dopant and situated within the contact hole; and

a compound of both the refractory metal and the dopant situated within the contact hole between the refractory metal silicide and the silicon-containing material.

40. A method as recited in claim 39, wherein the refractory metal is titanium.

41. A method of forming a contact structure to provide electrical communication to a semiconductor device on an in-process integrated circuit substrate, the method comprising:

forming a contact opening through an insulating layer above the semiconductor device, wherein the contact opening has a bottom and defines a sidewall in the insulating layer, the insulating layer comprising oxide;

forming, in an atmosphere devoid of flooring, a layer of refractory metal in the bottom of the contact opening;

forming a layer of electrically conductive silicon-containing material on the layer of refractory metal in the contact opening, the layer of electrically conductive silicon-containing material being doped, and wherein the layer of electrically conductive silicon-containing material adheres to the oxide of the sidewall in the insulating layer and is formed from a silane precursor in an atmosphere of B₂H₆ at a temperature in a range of about 630°

C. to about 650°

C.; and

annealing the in-process integrated circuit substrate.