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

• US 6,475,276 B1
• Filed: 10/13/2000
• Issued: 11/05/2002
• Est. Priority Date: 10/15/1999
• Status: Expired due to Term

• Current Assignee: ASM International NV
• Original Assignee: ASM Microchemistry Oy (ASM International NV)
• Inventors: Elers, Kai-Erik, Soininen, Pekka Juha, Saanila, Ville Antero, Kaipio, Sari Johanna
• Primary Examiner(s): MEEKS, TIMOTHY HOWARD
• Application Number:
  US09/687,205
• Time in Patent Office: 753 Days
• Field of Search: 117/88, 117/84, 427/250, 427/253, 427/255.28, 438/680, 438/685, 438/687
• US Class Current: 117/84
• 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, comprising alternately introducing vapor phase pulses of at least one elemental source compound and at least one boron source compound into a reaction space containing the substrate, wherein the boron source compound contains at least one carbon atom.

2. The method of claim 1, wherein the method is an atomic layer deposition (ALD) type process.

3. The method of claim 2, wherein the vapor phase pulses are alternately introduced in a cycle comprising:

introducing an elemental source compound into a reaction space containing a substrate; and

removing any gaseous compounds from the reaction space; and

introducing a boron source compound into the reaction space; and

removing any gaseous compounds from the reaction space.

4. The method of claim 1, wherein the elemental source compound reacts with the surface of the substrate, thereby producing a surface bound elemental complex.

5. The method of claim 4, wherein the boron source compound reduces the surface bound elemental complex into its elemental state.

6. The method of claim 5, wherein gaseous reaction byproducts are formed by the reduction of the surface bound elemental complex into it elemental state.

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

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

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

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

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

12. The method of claim 1, wherein the elemental source compound comprises a metal selected from the group consisting of Cu, Ag, Au, Pd, Pt, Rh and Ir.

13. The method of claim 1, 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.

14. The method of claim 13, 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.

15. The method of claim 1, 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.

16. The method of claim 1, 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.

17. The method of claim 1, 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.

18. A method of growing an elemental thin film on a substrate from vapor phase reactants, comprising alternately introducing vapor phase pulses of at least one elemental source compound and at least one boron source compound into a reaction space containing the substrate, wherein the boron source compound contains no carbon atoms and wherein the boron source compound is selected from the group consisting of boron halides, borane halides and complexes thereof.

19. The method of claim 18, wherein the boron source compound is selected from the group consisting of boron halides having a boron/halide ratio between 0.5 and 1.

20. The method of claim 19, wherein the boron source compound is selected from the group consisting of B₂F₄, B₂Cl₄ and B₂Br₄.

21. The method of claim 18, wherein the boron source compound 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.

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

23. The method of claim 22, wherein vapor phase pulses are alternately introduced to the substrate in a cycle comprising:

introducing a vapor-phase metal source compound into a reaction space containing the substrate; and

removing any gaseous compounds from the reaction space; and

introducing the boron compound into the reaction space; and

removing any gaseous compounds from the reaction space.

24. The method of claim 23, wherein at least a portion of the metal source compound chemisorbs upon the substrate, thereby producing the adsorbed metal complex.

25. The method of claim 22, wherein the metal complex comprises a metal selected from the group consisting of Cu, Ag, Au, Pd, Pt, Rh and Ir.

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

introducing a metal source gas into a reaction space holding a substrate;

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

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

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

27. The method of claim 26, wherein introducing the metal source gas comprises saturating the substrate with no more than a monolayer of an adsorbed metal complex.

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

29. A method of growing a metal layer on a substrate by an atomic layer deposition (ALD) process, comprising adsorbing a metal complex upon the substrate and reducing the metal complex to its elemental state by exposing the substrate to a vapor-phase boron compound, wherein the boron compound contains at least one carbon atom.

30. The method of claim 29, wherein the metal complex comprises at least one metal selected from the group consisting of Cu, Ag, Au, Pd, Pt, Rh and Ir.

31. The method of claim 30, wherein the boron 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.

32. The method of claim 30, wherein the boron 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.

33. The method of claim 30, wherein the boron 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.

34. The method of claim 30, wherein the boron 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.

35. The method of claim 30, wherein the boron 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.

36. The method of claim 29, wherein the metal layer comprises an electrodeposition seed layer in an integrated circuit metallization scheme.

37. A method of growing a metal layer on a substrate by an atomic layer deposition (ALD) process, comprising adsorbing a metal complex upon the substrate and reducing the metal complex to its elemental state by exposing the substrate to a vapor-phase boron compound, wherein the boron compound does not contain a carbon atom and 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, and wherein the boron compound is selected from the group consisting of boron halides, borane halides and complexes thereof.

38. The method of claim 37, wherein the boron compound is selected from the group consisting of boron halides having a boron/halide ratio between 0.5 and 1.

39. The method of claim 38, wherein the boron compound is selected from the group consisting of B₂F₄, B₂Cl₄ and B₂Br₄.

40. The method of claim 37, wherein the boron compound 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.