Zirconium and/or hafnium silicon-oxynitride gate dielectric

• US 6,020,243 A
• Filed: 07/15/1998
• Issued: 02/01/2000
• Est. Priority Date: 07/24/1997
• Status: Expired due to Term

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Wallace, Robert M., Stoltz, Richard A., Wilk, Glen D.
• Primary Examiner(s): Thomas, Tom
• Assistant Examiner(s): SOUW, BERNARD E
• Application Number:
  US09/115,859
• Time in Patent Office: 566 Days
• Field of Search: 438/287, 438/216, 438/240, 438/591, 438/785, 438/786, 438/769, 438/775, 257/410, 257/411, 257/310
• US Class Current: 438/287
• CPC Class Codes: H01L 21/0214 the material being a silicon oxynitride, e.g. SiON or SiON:H
• CPC Class Codes: H01L 21/02181 the material containing hafnium, e.g. HfO2
• CPC Class Codes: H01L 21/02189 the material containing zirconium, e.g. ZrO2
• CPC Class Codes: H01L 21/02194 the material containing more than one metal element
• CPC Class Codes: H01L 21/02249 formation by combined oxidation and nitridation performed simultaneously
• CPC Class Codes: H01L 21/28185 with a treatment, e.g. annealing, after the formation of the gate insulator and before the formation of the definitive gate conductor
• CPC Class Codes: H01L 21/28194 by deposition, e.g. evaporation, ALD, CVD, sputtering, laser deposition H01L21/28202 takes precedence
• CPC Class Codes: H01L 21/28202 in a nitrogen-containing ambient, e.g. nitride deposition, growth, oxynitridation, NH3 nitridation, N2O oxidation, thermal nitridation, RTN, plasma nitridation, RPN
• CPC Class Codes: H01L 21/28229 by deposition of a layer, e.g. metal, metal compound or poysilicon, followed by transformation thereof into an insulating layer
• CPC Class Codes: H01L 21/3143 composed of alternated layers or of mixtures of nitrides and oxides or of oxinitrides, e.g. formation of oxinitride by oxidation of nitride layers
• CPC Class Codes: H01L 21/31612 on a silicon body
• 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 21/31691 with perovskite structure
• 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 29/518 the insulating material containing nitrogen, e.g. nitride, oxynitride, nitrogen-doped material

Abstract

A field effect semiconductor device comprising a high permittivity zirconium (or hafnium) silicon-oxynitride gate dielectric and a method of forming the same are disclosed herein. The device comprises a silicon substrate 20 having a semiconducting channel region 24 formed therein. A zirconium silicon-oxynitride gate dielectric layer 36 is formed over this substrate, followed by a conductive gate 38. Zirconium silicon-oxynitride gate dielectric layer 36 has a dielectric constant is significantly higher than the dielectric constant of silicon dioxide. However, the zirconium silicon-oxynitride gate dielectric may also be designed to have the advantages of silicon dioxide, e.g. high breakdown, low interface state density, and high stability.

Claims

1. A method of fabricating a field-effect device on an integrated circuit, the method comprising:

providing a single-crystal silicon substrate;

forming a metal silicon-oxynitride gate dielectric layer on the substrate,

where the metal is selected from the group consisting of hafnium, zirconium, and mixtures thereof; and

forming a conductive gate overlying the gate dielectric layer.

2. The method of claim 1, wherein the metal is substantially pure zirconium.

3. The method of claim 1, wherein the forming a metal silicon-oxynitride dielectric layer step comprises:

forming a metal silicide on the substrate,

where the metal silicide is selected from the group consisting of hafnium silicide, zirconium silicide, and mixtures thereof; and

annealing the formed metal silicide in an atmosphere including oxygen and nitrogen, thereby forming a metal silicon-oxynitride layer on the substrate.

4. The method of claim 3, where the atmosphere includes NO.

5. The method of claim 3, where the atmosphere includes a nitrogen/oxygen plasma, the plasma generated remotely from the substrate.

6. The method of claim 3, where the annealing time is limited, such that the nitrogen to silicon ratio of the metal silicon-oxynitride layer is lower near the interface with the silicon substrate than near the interface with the conductive gate.

7. The method of claim 3, where the forming a metal silicide step comprises chemical vapor deposition.

8. The method of claim 3, wherein the forming a metal silicide step comprises:

depositing a metal layer on the substrate in an inert atmosphere,

where the metal is selected from the group consisting of hafnium, zirconium, and mixtures thereof; and

annealing the substrate and metal layer in an inert atmosphere to form a metal silicide layer.

9. The method of claim 8, wherein the substrate comprises a clean Si surface immediately prior to the depositing step.

10. The method of claim 8, where the depositing a metal layer comprises chemical vapor deposition.

11. The method of claim 10, where the chemical vapor deposition uses a nitrogen-bearing precursor.

12. The method of claim 1, wherein the forming a metal silicon-oxynitride dielectric layer step comprises:

forming a partially-reduced metal silicate on the substrate,

where the metal silicate is selected from the group consisting of hafnium silicate, zirconium silicate, and mixtures thereof;

annealing the formed metal silicate in a non-oxidizing atmosphere including nitrogen, thereby forming a reduced metal silicon-oxynitride layer on the substrate; and

annealing the reduced metal silicon-oxynitride layer in an oxidizing ambient, thereby forming a metal silicon-oxynitride layer on the substrate.

13. The method of claim 12, wherein the non-oxidizing atmosphere is a remote nitrogen plasma.

14. The method of claim 12, wherein the forming a partially-reduced metal silicate step comprises:

depositing a metal oxide layer on the substrate in an inert atmosphere,

where the metal oxide is selected from the group consisting of hafnium oxide, zirconium oxide, and mixtures thereof; and

annealing the substrate and metal oxide layer in an inert atmosphere to form a partially-reduced metal silicate layer.

15. The method of claim 1, wherein the forming a metal silicon-oxynitride dielectric layer step comprises:

forming a metal silicide on the substrate,

where the metal silicide is selected from the group consisting of hafnium silicide, zirconium silicide, and mixtures thereof;

annealing the formed metal silicide in a non-oxidizing atmosphere including nitrogen, thereby forming a metal silicon-nitride layer on the substrate; and

annealing the metal silicon-nitride layer in an oxidizing ambient, thereby forming a metal silicon-oxynitride layer on the substrate.

16. The method of claim 15, wherein the non-oxidizing atmosphere includes atomic nitrogen.

17. The method of claim 15, where the forming a metal silicide step comprises chemical vapor deposition.

18. The method of claim 15, wherein the forming a metal silicide step comprises:

depositing a metal layer on the substrate in an inert atmosphere,

where the metal is selected from the group consisting of hafnium, zirconium, and mixtures thereof; and

annealing the substrate and metal layer in an inert atmosphere to form a metal silicide layer.

19. The method of claim 1, wherein the forming a metal silicon-oxynitride dielectric layer step comprises depositing a metal silicide on the substrate in an atmosphere including oxygen and nitrogen, thereby forming a metal silicon-oxynitride layer on the substrate;

where the metal silicide is selected from the group consisting of hafnium silicide, zirconium silicide, and mixtures thereof.

20. The method of claim 19, where depositing a metal silicide comprises sputtering material from a target comprised of the metal silicide onto the substrate.

21. The method of claim 19, where depositing a metal silicide comprises evaporating a first metal and silicon from a common source.

22. The method of claim 19, where depositing a metal silicide comprises evaporating a first metal and silicon from separate sources.

23. The method of claim 22, wherein the evaporation rate of the separate sources are independently varied during the depositing step, thereby forming a metal silicon-oxynitride dielectric layer having a depth-varying ratio of the first metal to silicon.

24. The method of claim 23, where the metal to silicon ratio is lower near the interface with the silicon substrate than near the center of the metal silicon-oxynitride layer.

25. The method of claim 19, where the atmosphere includes NO.

26. The method of claim 19, where the atmosphere includes N₂ O.

27. The method of claim 19, further comprising annealing the metal silicon-oxynitride layer.

28. The method of claim 27, wherein the annealing step is carried out at a temperature sufficient to crystallize the metal silicon-oxynitride layer.

29. The method of claim 1, wherein the forming a metal silicon-oxynitride dielectric layer step comprises forming a silicon dioxide layer on the substrate;

and

simultaneously exposing the silicon dioxide layer to a nitrogen plasma and a metal plasma, where the metal is selected from the group consisting of hafnium, zirconium, and mixtures thereof;

where the plasmas are generated remotely from the substrate.

30. An integrated circuit made by the method of claim 1.

31. An integrated circuit made by the method of claim 19.

32. An integrated circuit made by the method of claim 4.

33. An integrated circuit made by the method of claim 15.