Surface preparation prior to deposition on germanium

• US 20050106893A1
• Filed: 08/03/2004
• Published: 05/19/2005
• Est. Priority Date: 08/04/2003
• Status: Active Grant

• Current Assignee: ASM IP Holding B.V. (ASM International NV)
• Original Assignee: ASM America Incorporated (ASM International NV)
• Inventors: Wilk, Glen
• Granted Patent: US 7,202,166 B2
• Time in Patent Office: Days
• US Class Current: 438/758
• CPC Class Codes: C23C 16/0245 by etching with a plasma
• CPC Class Codes: C23C 16/0281 of metallic sub-layers C23C16/029 takes precedence
• CPC Class Codes: C23C 16/405 of refractory metals or yttrium
• CPC Class Codes: C23C 16/45525 Atomic layer deposition [ALD]
• CPC Class Codes: H01L 21/02178 the material containing aluminium, e.g. Al2O3
• CPC Class Codes: H01L 21/02189 the material containing zirconium, e.g. ZrO2
• CPC Class Codes: H01L 21/0228 deposition by cyclic CVD, e.g. ALD, ALE, pulsed CVD
• CPC Class Codes: H01L 21/02312 treatment by exposure to a gas or vapour
• CPC Class Codes: H01L 21/02315 treatment by exposure to a plasma
• CPC Class Codes: H01L 21/28158 Making the insulator
• CPC Class Codes: H01L 21/28194 by deposition, e.g. evaporation, ALD, CVD, sputtering, laser deposition H01L21/28202 takes precedence
• CPC Class Codes: H01L 21/28255 the insulator being formed after the semiconductor body, the semiconductor belonging to Group IV and not being elemental silicon, e.g. Ge, SiGe, SiGeC
• CPC Class Codes: H01L 21/3141 Deposition using atomic layer deposition techniques [ALD]
• CPC Class Codes: H01L 21/3145 formed by deposition from a gas or vapour
• CPC Class Codes: H01L 21/31604 Deposition from a gas or vapour H01L21/31691, H01L21/31695 take precedence
• CPC Class Codes: H01L 21/31616 Deposition of Al2O3
• CPC Class Codes: H01L 21/31637 Deposition of Tantalum oxides, e.g. Ta2O5
• CPC Class Codes: H01L 21/31641 Deposition of Zirconium oxides, e.g. ZrO2
• CPC Class Codes: H01L 21/31645 Deposition of Hafnium oxides, e.g. HfO2
• CPC Class Codes: H01L 21/31658 by thermal oxidation, e.g. of SiGe
• CPC Class Codes: H01L 29/1054 : with a variation of the composition, e.g. channel with strained layer for increasing the mobility
• CPC Class Codes: H01L 29/16 : including, apart from doping materials or other impurities, only elements of Group IV of the Periodic Table
• CPC Class Codes: H01L 29/513 : the variation being perpendicular to the channel plane
• CPC Class Codes: H01L 29/517 : the insulating material comprising a metallic compound, e.g. metal oxide, metal silicate H01L29/518 takes precedence
• CPC Class Codes: H01L 29/66477 : with an insulated gate, i.e. MISFET

Abstract

Methods are provided for treating germanium surfaces in preparation for subsequent deposition, particularly gate dielectric deposition by atomic layer deposition (ALD). Prior to depositing, the germanium surface is treated with plasma products or thermally reacted with vapor reactants. Examples of surface treatments leave oxygen bridges, nitrogen bridges, —OH, —NH and/or —NH₂ terminations that more readily adsorb ALD reactants. The surface treatments avoid deep penetration of the reactants into the germanium bulk but improve nucleation.

Claims

1. A method of depositing a film over a germanium surface in fabricating an integrated circuit, comprising:

exposing the germanium surface to an oxygen- and/or nitrogen-containing vapor, thereby forming a modified surface; and

atomic layer depositing a dielectric material over the modified surface.

2. The method of claim 1, wherein the oxygen- and/or nitrogen-containing vapor comprises excited species from a remote plasma generator.

3. The method of claim 1, wherein exposing comprises thermally reacting the oxygen and/or nitrogen-containing vapor with the germanium surface.

4. The method of claim 1, wherein exposing comprises forming less than about 10 atomic % nitrogen and less than about 10 atomic % oxygen at depth of about 10 Å

or greater below the germanium surface.

5. The method of claim 1, wherein the oxygen and/or nitrogen-containing vapor comprises a gas selected from the group consisting of O₂, O₃, H₂O, H₂O, NO, N₂O, N₂O, N₂, N₂/H₂, HCOOH, HClO₃, CO₂, and mixtures of the foregoing.

6. The method of claim 1, wherein exposing comprises maintaining the germanium surface at a temperature below about 500°

C.

7. The method of claim 6, wherein exposing comprises maintaining the germanium surface at a temperature below about 300°

C.

8. The method of claim 1, wherein the germanium surface comprises a single crystal structure having a germanium content greater than about 90 atomic %.

9. The method of claim 1, wherein the germanium surface comprises a top surface of a silicon germanium layer having a germanium content greater than about 20 atomic %.

10. The method of claim 9, wherein the germanium surface comprises a top surface of a silicon germanium layer having a germanium content greater than about 40 atomic %.

11. The method of claim 1, wherein atomic layer depositing comprises alternating at least one metal precursor with an oxygen precursor.

12. The method of claim 11, wherein the gate dielectric layer is characterized by a dielectric constant greater than about 5.

13. The method of claim 12, wherein the gate dielectric layer is characterized by a dielectric constant greater than about 10.

14. The method of claim 1, wherein exposing and atomic layer depositing are performed in situ in a single deposition chamber.

15. The method of claim 1, wherein exposing does not deposit a layer greater than about one atomic monolayer.

16. A method of deposing on a germanium surface, the method comprising:

providing a germanium surface;

forming a surface termination across the germanium surface, the surface termination selected from the group consisting of oxygen bridges, nitrogen bridges, —

OH groups, —

NH groups, —

NH₂ and mixtures of the foregoing;

vapor depositing a layer directly over the surface termination.

17. The method of claim 16, wherein vapor depositing comprises atomic layer deposition.

18. The method of claim 17, wherein the layer comprises a dielectric material having a dielectric constant greater than that of silicon nitride.

19. The method of claim 18, wherein the layer comprises a dielectric material selected from the group consisting of aluminum oxide, zirconium oxide, hafnium oxide, tantalum oxide and ternary oxides.

20. The method of claim 16, wherein forming the surface termination comprises providing excited species from a remote plasma generator.

21. The method of claim 16, wherein forming the surface termination comprises thermal reaction of the germanium substrate with vapor reactants at less than about 500°

C.

22. The method of claim 16, wherein forming the surface termination comprises diffusing nitrogen and oxygen to depth of no more than 15 Å

below the germanium surface.

23. The method of claim 22, wherein forming the surface termination comprises leaving less than about 10 atomic % nitrogen and less than about 10 atomic % oxygen at a depth of 10 Å

or greater below the surface termination.

24. The method of claim 16, wherein forming the surface termination comprises nitridizing and/or oxidizing a top 2-5 Å

of the germanium structure.

25. An integrated circuit, comprising:

a semiconductor structure with greater than about 40 atomic % germanium;

a gate dielectric layer over the semiconductor structure, the layer having a thickness of no more than about 50 Å and

a surface roughness no more than about 3 Å

rms; and

nitrogen and/or oxygen at an interface between the germanium structure and the gate dielectric, wherein the semiconductor structure has less than less than about 10 atomic % oxygen at a depth of greater than about 10 Å

from an upper surface of the semiconductor structure.

26. The integrated circuit of claim 25, wherein the gate dielectric comprises a material selected from the group consisting of aluminum oxide, zirconium oxide, hafnium oxide, tantalum oxide, barium strontium titanate and strontium bismuth tantalate.

27. The integrated circuit of claim 26, wherein the gate dielectric comprises zirconium oxide.

28. The integrated circuit of claim 25, comprising 2-5 Å

of germanium nitride at the interface.

29. The integrated circuit of claim 25, comprising 2-5 Å

of germanium oxide at the interface.

30. The integrated circuit of claim 25, comprising 2-5 Å

of germanium oxynitride at the interface.

31. The integrated circuit of claim 25, wherein the semiconductor structure has less than less than about 10 atomic % nitrogen at a depth of greater than about 10 Å

from an upper surface of the semiconductor structure.

32. The integrated circuit of claim 31, wherein the semiconductor structure has less than less than about 1 atomic % oxygen and less than about 1 atomic % nitrogent at a depth of equal to or greater than about 30 Å

from an upper surface of the semiconductor structure

33. A method of depositing a film over a germanium surface in fabricating an integrated circuit, comprising:

providing a germanium structure having greater than about 40 atomic % germanium content;

exposing a surface of the germanium structure to a surface treatment for improved nucleation of an atomic layer deposition reactant; and

atomic layer depositing a layer over the treated surface using the atomic layer deposition reactant.