Production of elemental thin films using a boron-containing reducing agent

• US 6,821,889 B2
• Filed: 07/30/2002
• Issued: 11/23/2004
• Est. Priority Date: 10/15/1999
• Status: Expired due to Term

• Current Assignee: ASM International NV
• Original Assignee: ASM International NV
• Inventors: Kaipio, Sari Johanna, Elers, Kai-Erik, Soininen, Pekka Juha, Saanila, Ville Antero
• Primary Examiner(s): MEEKS, TIMOTHY HOWARD
• Application Number:
  US10/210,715
• Publication Number:
  US 20020187256A1
• Time in Patent Office: 847 Days
• Field of Search: 427/250, 427/253, 427/255.28, 438/680, 438/685, 438/687, 117/84, 117/88
• US Class Current: 438/680
• CPC Class Codes: C23C 16/0272 Deposition of sub-layers, e.g. to promote the adhesion of the main coating
• CPC Class Codes: C23C 16/045 Coating cavities or hollow spaces, e.g. interior of tubes; Infiltration of porous substrates
• CPC Class Codes: C23C 16/08 from metal halides
• CPC Class Codes: C23C 16/14 Deposition of only one other metal element
• CPC Class Codes: C23C 16/32 Carbides
• CPC Class Codes: C23C 16/34 Nitrides C23C16/303 takes precedence
• CPC Class Codes: C23C 16/44 characterised by the method of coating C23C16/04 takes precedence
• CPC Class Codes: C23C 16/4401 Means for minimising impurities, e.g. dust, moisture or residual gas, in the reaction chamber
• CPC Class Codes: C23C 16/45525 Atomic layer deposition [ALD]
• CPC Class Codes: C23C 16/45527 characterized by the ALD cycle, e.g. different flows or temperatures during half-reactions, unusual pulsing sequence, use of precursor mixtures or auxiliary reactants or activations
• CPC Class Codes: C23C 16/45542 Plasma being used non-continuously during the ALD reactions
• CPC Class Codes: C23C 16/45553 characterized by the use of precursors specially adapted for ALD
• CPC Class Codes: C23C 16/45555 applied in non-semiconductor technology
• CPC Class Codes: C30B 25/02 Epitaxial-layer growth
• CPC Class Codes: C30B 25/14 Feed and outlet means for the gases; Modifying the flow of the reactive gases
• CPC Class Codes: C30B 29/02 Elements
• CPC Class Codes: C30B 29/36 Carbides
• CPC Class Codes: C30B 29/38 Nitrides
• CPC Class Codes: H01L 21/28562 Selective deposition
• CPC Class Codes: H01L 21/28568 the conductive layers comprising transition metals H01L21/28518 takes precedence
• CPC Class Codes: H01L 21/76807 : for dual damascene structures
• CPC Class Codes: H01L 21/76838 : characterised by the formation and the after-treatment of the conductors etching for patterning the conductors H01L21/3213
• CPC Class Codes: H01L 21/76843 : formed in openings in a dielectric
• CPC Class Codes: H01L 21/76871 : Layers specifically deposited to enhance or enable the nucleation of further layers, i.e. seed layers
• CPC Class Codes: H01L 21/76876 : for deposition from the gas phase, e.g. CVD
• CPC Class Codes: H01L 21/76877 : Filling of holes, grooves or trenches, e.g. vias, with conductive material
• CPC Class Codes: H01L 23/5226 : Via connections in a multilevel interconnection structure
• CPC Class Codes: H01L 23/53223 : Additional layers associated with aluminium layers, e.g. adhesion, barrier, cladding layers
• CPC Class Codes: H01L 23/53228 : the principal metal being copper
• CPC Class Codes: H01L 23/53238 : Additional layers associated with copper layers, e.g. adhesion, barrier, cladding layers
• CPC Class Codes: H01L 23/53242 : the principal metal being a noble metal, e.g. gold
• CPC Class Codes: H01L 23/53252 : Additional layers associated with noble-metal layers, e.g. adhesion, barrier, cladding layers
• CPC Class Codes: H01L 23/5329 : Insulating materials
• CPC Class Codes: H01L 23/53295 : Stacked insulating layers
• 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

The present invention relates generally to depositing elemental thin films. In particular, the invention concerns a method of growing elemental metal thin films by Atomic Layer Deposition (ALD) using a boron compound as a reducing agent. In a preferred embodiment the method comprises introducing vapor phase pulses of at least one metal source compound and at least one boron source compound into a reaction space that contains a substrate on which the metal thin film is to be deposited. Preferably the boron compound is capable of reducing the adsorbed portion of the metal source compound into its elemental electrical state.

Claims

1. A method of growing an elemental thin film on a substrate from vapor phase reactants in an atomic layer deposition (ALD) process comprising:

introducing a vapor phase metal source compound into a reaction space containing the substrate such that no more than one molecular layer of the metal source compound adsorbs on the substrate;

removing any vapor phase compounds from the reaction space;

contacting the adsorbed metal source compound on the substrate with a vapor phase boron source compound such that no more than one atomic layer of elemental metal is formed on the substrate; and

removing any gaseous compounds from the reaction space.

2. The method of claim 1, wherein the ALD process is repeated to form an elemental thin film of a desired thickness.

3. The method of claim 2, wherein the ALD process is repeated until an elemental thin film with a thickness of from one atomic layer to 1000 nm is formed.

4. The method of claim 1, wherein the boron source compound reduces the adsorbed metal source compound into its elemental state.

5. The method of claim 4, wherein gaseous reaction byproducts are formed by the reduction of the adsorbed metal source compound into its elemental state.

6. The method of claim 1, wherein the metal source compound and boron source compound are fed into the reaction chamber with the aid of an inert carrier gas.

7. The method of claim 1, further comprising feeding an inert gas pulse to the reaction chamber after each pulse of metal source compound and the vapor phase boron source compound.

8. The method of claim 7, further comprising adding a mild reducing agent to the inert gas pulse.

9. The method of claim 8, wherein the inert gas pulse comprises 0.5% to 1% of the mild reducing agent by volume.

10. The method of claim 9, wherein the mild reducing agent is hydrogen.

11. The method of claim 1, wherein the boron source compound contains no carbon atoms.

12. The method of claim 11, wherein the metal source compound comprises at least one metal selected from the group consisting of Cu, Ag, Au, Pd, Pt, Rh, Ir, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo and W.

13. The method of claim 11, wherein the boron source compound is selected from the group consisting of boranes of formula B_nH_n+x, wherein n is an integer from 1 to 10 and x is an even integer.

14. The method of claim 13, wherein the boron source compound is selected from the group consisting of nido-boranes of formula B_nH_n+4, arachno-boranes of the formula B_nH_n+6, hypho-boranes of the formula B_nH_n+8 and conjuncto-boranes B_nH_m, wherein n is an integer from 1 to 10 and m is an integer from 1 to 10 that is different from n.

15. The method of claim 1, wherein the boron source compound is in the form of a complex.

16. The method of claim 1, wherein the metal source compound comprises a metal selected from the group consisting of Cu, Ag, Au, Pd, Pt, Rh, Ir, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo and W.

17. The method of claim 16, wherein the metal source compound is a tungsten compound.

18. The method of claim 17, wherein the tungsten compound is tungsten hexafluoride (WF₆).

19. The method of claim 1, wherein the elemental thin film forms an electrodeposition seed layer in an integrated circuit metallization scheme.

20. The method of claim 19, wherein the seed layer consists essentially of tungsten metal.

21. The method of claim 1, wherein the reaction space is maintained at a constant temperature during the ALD process.

22. The method of claim 21, wherein the temperature is between about 100°

C. and about 700°

C.

23. The method of claim 22, wherein the temperature is between about 250°

C. and about 500°

C.

24. The method of claim 1, wherein the reaction space is maintained at a constant pressure during the ALD process.

25. The method of claim 24, wherein the pressure is between about 0.01 mbar and about 20 mbar.

26. A method of growing an elemental thin film on a substrate from vapor phase reactants in an atomic layer deposition (ALD) process comprising:

introducing a vapor phase metal source compound into a reaction space containing the substrate such that no more than one molecular layer of the metal source compound adsorbs on the substrate;

removing any vapor phase compounds from the reaction space;

contacting the adsorbed metal source compound on the substrate with a vapor phase boron source compound such that no more than one atomic layer of elemental metal is formed on the substrate; and

removing any gaseous compounds from the reaction space, wherein the boron source compound contains at least one carbon atom.

27. The method of claim 26, wherein the metal source compound comprises a metal selected from the group consisting of Cu, Ag, Au, Pd, Pt, Rh and Ir.

28. The method of claim 26, wherein the boron source compound is selected from the group consisting of carboranes according to the formula C₂B_nH_n+x, wherein n is an integer from 1 to 10 and x is an even integer.

29. The method of claim 28, wherein the boron source compound is selected from the group consisting of closo-carboranes of the formula C₂B_nH_n+2, nido-carboranes of the formula C₂B_nH_n+4 and arachno-carboranes of the formula C₂B_nH_n+6, wherein n is an integer from 1 to 10.

30. The method of claim 26, wherein the boron source compound is selected from the group consisting of amine-borane adducts according to the formula R₃NBX₃ wherein R is linear or branched C1 to C10 or H and X is linear or branched C1 to C10, H or a halogen.

31. The method of claim 26, wherein the boron source compound is selected from the group consisting of aminoboranes, wherein one or more of the substituents is an amino group according to the formula R₂N, wherein R is linear or branched C1 to C10 or a substituted or unsubstituted aryl group.

32. The method of claim 26, wherein the boron source compound is selected from the group consisting of alkyl borons and alkyl boranes, wherein the alkyl is a linear or branched C1 to C10 alkyl.

33. A method of growing an elemental thin film on a substrate from vapor phase reactants in an atomic layer deposition (ALD) process comprising:

introducing a vapor phase metal source compound into a reaction space containing the substrate such that no more than one molecular layer of the metal source compound adsorbs on the substrate;

removing any vapor phase compounds from the reaction space;

contacting the adsorbed metal source compound on the substrate with a vapor phase boron source compound such that no more than one atomic layer of elemental metal is formed on the substrate; and

removing any gaseous compounds from the reaction space, wherein the boron source compound contains no carbon atoms and is selected from the group consisting of boron halides and complexes thereof.

34. The method of claim 33, wherein the boron source compound is selected from the group consisting of boron halides having a boron/halide ratio between 0.5 and 1.

35. The method of claim 34, wherein the boron source compound is selected from the group consisting of B₂F₄, B₂Cl₄ and B₂Br₄.

36. A method of growing an elemental thin film on a substrate from vapor phase reactants in an atomic layer deposition (ALD) process comprising:

introducing a vapor phase metal source compound into a reaction space containing the substrate such that no more than one molecular layer of the metal source compound adsorbs on the substrate;

removing any vapor phase compounds from the reaction space;

contacting the adsorbed metal source compound on the substrate with a vapor phase boron source compound such that no more than one atomic layer of elemental metal is formed on the substrate; and

removing any gaseous compounds from the reaction space, wherein the boron source compound contains no carbon atoms and is selected from the group consisting of halogenoboranes of the formula B_nX_n, wherein X is Cl or Br and n is 4 or an integer from 8 to 12 when X is Cl or n is an integer from 7 to 10 when X is Br.

37. A method of growing an elemental thin film on a substrate from vapor phase reactants in an atomic layer deposition (ALD) process comprising:

introducing a vapor phase metal source compound into a reaction space containing the substrate such that no more than one molecular layer of the metal source compound adsorbs on the substrate;

removing any vapor phase compounds from the reaction space;

contacting the adsorbed metal source compound on the substrate with a vapor phase boron source compound such that no more than one atomic layer of elemental metal is formed on the substrate; and

removing any gaseous compounds from the reaction space, wherein the boron source compound is selected from the group consisting of cyclic borazine and volatile derivatives thereof.

38. A method of growing an elemental metal thin film in a dual damascene structure by an atomic layer deposition (ALD) process comprising:

introducing a vapor phase metal source compound into a reaction space containing the substrate with an inert carrier gas;

contacting the substrate with the vapor phase metal source compound such that no more than one molecular layer of the metal source compound adsorbs on the substrate;

removing any vapor phase compounds from the reaction space;

introducing a vapor phase boron source compound into the reaction space with the inert carrier gas;

contacting the adsorbed metal source compound on the substrate with the vapor phase boron source compound; and

removing any gaseous compounds from the reaction space,

wherein the inert carrier gas comprises a mild reducing agent.

39. The method of claim 38, wherein the inert carrier gas comprises about 0.5% to about 1% of the mild reducing agent by volume.

40. The method of claim 39, wherein the mild reducing agent is hydrogen.

41. The method of claim 38, wherein the boron source compound does not comprise a carbon atom.

42. The method of claim 38, wherein the metal source compound comprises at least one metal selected from the group consisting of Cu, Ag, Au, Pd, Pt, Rh, Ir, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo and W.

43. A method of growing an elemental metal thin film in a dual damascene structure by an atomic layer deposition (ALD) process comprising:

introducing a vapor phase metal source compound into a reaction space containing the substrate with an inert carrier gas;

contacting the substrate with the vapor phase metal source compound such that no more than one molecular layer of the metal source compound adsorbs on the substrate;

removing any vapor phase compounds from the reaction space;

introducing a vapor phase boron source compound into the reaction space with the inert carrier gas;

contacting the adsorbed metal source compound on the substrate with the vapor phase boron source compound; and

removing any gaseous compounds from the reaction space,

wherein the inert carrier gas comprises a mild reducing agent and the boron source compound comprises at least one carbon atom.

44. The method of claim 43, wherein the metal source compound comprises at least one metal selected from the group consisting of Cu, Ag, Au, Pd, Pt, Rh and Ir.

45. A method of producing an electron conductor in an integrated circuit by an atomic layer deposition (ALD) process, comprising adsorbing less than a monolayer of a metal complex on a substrate and exposing the adsorbed metal complex on the substrate to a boron compound, thereby reducing the metal complex to its elemental metal state.

46. The method of claim 45, wherein the boron compound does not comprise a carbon atom.

47. The method of claim 46, wherein the metal complex comprises at least one metal selected from the group consisting of Cu, Ag, Au, Pd, Pt, Rh, Ir, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo and W.

48. A method of producing an electron conductor in an integrated circuit by an atomic layer deposition (ALD) process, comprising adsorbing less than a monolayer of a metal complex on a substrate and exposing the adsorbed metal complex on the substrate to a boron compound, thereby reducing the metal complex to its elemental metal state, wherein the boron compound comprises at least one carbon atom.

49. The method of claim 48, wherein the metal complex comprises at least one metal selected from the group consisting of Cu, Ag, Au, Pd, Pt, Rh and Ir.

50. A method of producing an interconnect in an integrated circuit, the method comprising:

contacting a substrate in a reaction space with a metal source gas such that less than a monolayer of metal source gas adsorbs on the substrate surface;

removing any unreacted portion of the metal source gas and any gaseous reaction byproduct from the reaction space;

introducing a vapor-phase boron source gas into the reaction space; and

removing any unreacted portion of the boron source gas and any gaseous reaction byproduct from the reaction space.

51. The method of claim 50, wherein the boron source gas comprises a boron compound that does not comprise a carbon atom.

52. The method of claim 51, wherein the metal source gas comprises a metal selected from the group consisting of Cu, Ag, Au, Pd, Pt, Rh, Ir, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo and W.

53. A method of producing an interconnect in an integrated circuit, the method comprising:

contacting a substrate in a reaction space with a metal source gas such that less than a monolayer of metal source gas adsorbs on the substrate surface;

removing any unreacted portion of the metal source gas and any gaseous reaction byproduct from the reaction space;

introducing a vapor-phase boron source gas into the reaction space; and

removing any unreacted portion of the boron source gas and any gaseous reaction byproduct from the reaction space, wherein the boron source gas comprises a boron compound that comprises at least one carbon atom.

54. The method of claim 53, wherein the metal source gas comprises a metal selected from the group consisting of Cu, Ag, Au, Pd, Pt, Rh and Ir.