Non-activated guard ring for semiconductor devices

• US 20050202661A1
• Filed: 09/07/2004
• Published: 09/15/2005
• Est. Priority Date: 03/15/2004
• Status: Active Grant

• Current Assignee: Power Integrations Incorporated
• Original Assignee: Velox Semiconductor Corporation (Power Integrations Incorporated)
• Inventors: Shelton, Bryan S., Pophristic, Milan, Murphy, Michael, Liu, Linlin, Ceruzzi, Alex, Zhu, Ting Gang
• Granted Patent: US 7,229,866 B2
• Time in Patent Office: Days
• US Class Current: 438/570
• CPC Class Codes: H01L 29/0615 by the doping profile or the shape or the arrangement of the PN junction, or with supplementary regions, e.g. junction termination extension [JTE] LDD or drain offset regions H01L29/7833
• CPC Class Codes: H01L 29/0619 with a supplementary region doped oppositely to or in rectifying contact with the semiconductor containing or contacting region, e.g. guard rings with PN or Schottky junction
• CPC Class Codes: H01L 29/0634 Multiple reduced surface field (multi-RESURF) structures, e.g. double RESURF, charge compensation, cool, superjunction (SJ), 3D-RESURF, composite buffer (CB) structures
• CPC Class Codes: H01L 29/2003 Nitride compounds
• CPC Class Codes: H01L 29/207 further characterised by the doping material H01L29/2006 takes precedence
• CPC Class Codes: H01L 29/32 the imperfections being within the semiconductor body
• CPC Class Codes: H01L 29/452 on AIII-BV compounds
• CPC Class Codes: H01L 29/475 on AIII-BV compounds
• CPC Class Codes: H01L 29/66143 Schottky diodes
• CPC Class Codes: H01L 29/66212 Schottky diodes
• CPC Class Codes: H01L 29/872 Schottky diodes

Abstract

A guard ring is formed in a semiconductor region that is part of a Schottky junction or Schottky diode. The guard ring is formed by ion implantation into the semiconductor contact layer without completely annealing the semiconductor contact layer to form a high resistance region. The guard ring may be located at the edge of the layer or, alternatively, at a distance away from the edge of the layer. A Schottky metal contact is formed atop the layer, and the edges of the Schottky contact are disposed atop the guard ring.

Claims

1. A method of forming a guard ring in a semiconductor structure, said method comprising:

providing a semiconductor body including a contact layer;

implanting at least one ion species into at least one portion of said contact layer to form at least one implanted region therein, said at least one implanted region being disposed at least adjacent to a portion of a surface of said contact layer upon which an edge of a Schottky metallic contact is disposed or is to be disposed; and

subsequently processing said semiconductor body without completely annealing said implanted region.

2. A method as claimed in claim 1 wherein said implanted region adjoins said surface of said contact layer.

3. A method as claimed in claim 1 wherein an end of said implanted region adjoins said edge of said Schottky metallic contact.

4. A method as claimed in claim 1 wherein an end of said implanted region is located at an edge of said contact layer.

5. A method as claimed in claim 1 wherein said implanted region is located at least 1 μ

m away from said edge of said contact layer.

6. A method as claimed in claim 5 wherein said implanted region is located at most 10 μ

m away from said edge of said contact layer.

7. A method as claimed in claim 1 wherein said ion species is implanted at a dose of at least 5E12 cm⁻

2.

8. A method as claimed in claim 1 wherein said ion species is implanted at a dose of at most 1E16 cm⁻

1.

9. A method as claimed in claim 1 wherein said ion species is implanted at zero tilt angle with respect to said surface of said contact layer.

10. A method as claimed in claim 1 wherein said ion species is implanted at tilt angle at most 14 degrees with respect to said surface of said contact layer.

11. A method as claimed in claim 1 further comprising forming a masking layer at least atop said surface of said contact layer, and patterning said masking layer to define at least one opening therein through which said ion species is implanted into said portion of said doped region.

12. A method as claimed in claim 1 further comprising patterning and etching at least one region of said semiconductor body prior to said further processing to define a further surface in said semiconductor body and to define at least one mesa that projects upwardly from said further surface and that includes at least part of said contact layer.

13. A method as claimed in claim 12 wherein said patterning and etching steps are carried out prior to said implanting of said ion species.

14. A method as claimed in claim 13 wherein said ion species is implanted through a sidewall of said mesa.

15. A method as claimed in claim 12 wherein said implanting of said ion species is carried out prior to said patterning and etching steps, and said patterning and etching steps remove a portion of said implanted region.

16. A method as claimed in claim 1 wherein said contact layer includes a nitride-based semiconductor.

17. A method as claimed in claim 1 wherein said contact layer includes a gallium nitride-based semiconductor.

18. A method as claimed in claim 1 wherein said contact layer includes GaN.

19. A method as claimed in claim 1 wherein said subsequent processing is carried out without any annealing of said implanted region.

20. A method of forming a Schottky junction in a semiconductor structure, said method including:

forming a guard ring in said semiconductor structure as claimed in claim 1;

and

forming a metallic contact atop at least part of said contact layer to form a Schottky junction therewith.

21. A method of forming a Schottky diode including forming a guard ring as claimed in claim 1, wherein said step of providing a semiconductor body includes the step of forming at least one semiconductor layer on a surface of a substrate, said semiconductor layer at least including said contact layer, whereby said semiconductor body includes said substrate and said at least one semiconductor layer;

said method further comprising forming a metallic contact atop at least part of said contact layer to form a Schottky junction therewith.

22. A method as claimed in claim 21 further comprising forming at least one further metallic contact on said contact layer in substantially ohmic contact therewith.

23. A method as claimed in claim 21 further comprising patterning and etching at least one region of said semiconductor layer prior to forming said metallic contact to define at least one further surface in said semiconductor body and at least one mesa, said mesa projecting upwardly from said further surface and at least including said contact layer, said Schottky junction being disposed atop said mesa.

24. A method as claimed in claim 23 wherein said patterning and etching step is carried out prior to implanting said ion species.

25. A method as claimed in claim 23 wherein said further surface of said semiconductor body is a lower contact surface, and said method includes forming at least one further metallic contact on said lower contact surface in substantially ohmic contact therewith.

26. A method as claimed in claim 23 wherein said patterning and etching step includes patterning and etching one or more regions of said semiconductor body to define a plurality of mesas projecting upwardly from said further surface, at least some of said plurality of mesas each including at least one of said one or more guard rings.

27. A method as claimed in claim 21 wherein said substrate is an electrically insulating material.

28. A method as claimed in claim 21 wherein said substrate is a semiconductor, said method further including forming at least one further metallic contact on another surface of said substrate in substantially ohmic contact therewith.

29. A method of forming a Schottky diode including forming a guard ring as claimed in claim 1, wherein said step of providing a semiconductor body includes the step of forming at least one semiconductor layer on a surface of a substrate, said semiconductor layer at least including said contact layer, whereby said semiconductor body includes said substrate and said at least one semiconductor layer;

said method further comprising forming a metallic contact atop at least part of said contact layer to form a Schottky junction therewith prior to implanting said at least one ion species, said metallic contact masking said implanting of said at least one ion species such that said implanted region is self-aligned to said metallic contact.

30. A method as claimed in claim 29 further comprising forming at least one further metallic contact on said semiconductor layer in substantially ohmic contact therewith prior to implanting said at least one ion species, said ohmic contact further masking said implanting of said at least one ion species.

31. A method as claimed in claim 29 further comprising patterning and etching at least one region of said semiconductor layer prior to forming said metallic contact to define at least one lower contact surface in said semiconductor body and at least one mesa, said mesa projecting upwardly from said further surface and at least including said doped region, said Schottky metallic contact being formed atop said mesa;

said method further comprising forming at least one further metallic contact on said lower contact surface in substantially ohmic contact therewith prior to implanting said at least one ion species, said ohmic contact further masking said implanting of said at least one ion species.

32. A Schottky junction formed in a semiconductor structure by a method including:

forming a guard ring in said semiconductor structure as claimed in claim 1;

and

forming a metallic contact atop at least part of said contact layer to form a Schottky junction therewith.

33. A Schottky diode formed by a method including forming a guard ring as claimed in claim 1, wherein said step of providing a semiconductor body includes the step of forming at least one semiconductor layer on a surface of a substrate, said semiconductor layer at least including said contact layer, whereby said semiconductor body includes said substrate and said at least one semiconductor layer;

said method further comprising forming a metallic contact atop at least part of said contact layer to form a Schottky junction therewith.

34. A Schottky diode formed by a method as claimed in claim 33 further comprising forming at least one further metallic contact on said contact layer in substantially ohmic contact therewith.

35. A Schottky diode formed by a method as claimed in claim 33 further comprising patterning and etching at least one region of said semiconductor layer prior to forming said metallic contact to define at least one further surface in said semiconductor body and at least one mesa, said mesa projecting upwardly from said further surface and at least including said contact layer, said Schottky junction being disposed atop said mesa.

36. A Schottky diode formed by a method as claimed in claim 35 wherein said patterning and etching step is carried out prior to implanting said ion species.

37. A Schottky diode formed by a method as claimed in claim 35 wherein said further surface of said semiconductor body is a lower contact surface, and said method includes forming at least one further metallic contact on said lower contact surface in substantially ohmic contact therewith.

38. A Schottky diode formed by a method as claimed in claim 35 wherein said patterning and etching step includes patterning and etching one or more regions of said semiconductor body to define a plurality of mesas projecting upwardly from said further surface, at least some of said plurality of mesas each including at least one of said one or more guard rings.

39. A Schottky diode formed by a method as claimed in claim 33 wherein said substrate is an electrically insulating material.

40. A Schottky diode formed by a method as claimed in claim 33 wherein said substrate is a semiconductor, said method further including forming at least one further metallic contact on another surface of said substrate in substantially ohmic contact therewith.

41. A Schottky diode formed by a method including forming a guard ring as claimed in claim 1, wherein said step of providing a semiconductor body includes the step of forming at least one semiconductor layer on a surface of a substrate, said semiconductor layer at least including said contact layer, whereby said semiconductor body includes said substrate and said at least one semiconductor layer;

said method further comprising forming a metallic contact atop at least part of said contact layer to form a Schottky junction therewith prior to implanting said at least one ion species, said metallic contact masking said implanting of said at least one ion species such that said implanted region is self aligned to said metallic contact.

42. A Schottky diode formed by a method as claimed in claim 41 further comprising forming at least one further metallic contact on said semiconductor layer in substantially ohmic contact therewith prior to implanting said at least one ion species, said ohmic contact further masking said implanting of said at least one ion species.

43. A Schottky diode formed by a method as claimed in claim 41 further comprising patterning and etching at least one region of said semiconductor layer prior to forming said metallic contact to define at least one lower contact surface in said semiconductor body and at least one mesa, said mesa projecting upwardly from said further surface and at least including said doped region, said Schottky metallic contact being formed atop said mesa, and forming at least one further metallic contact on said lower contact surface in substantially ohmic contact therewith prior to implanting said at least one ion species, said ohmic contact further masking said implanting of said at least one ion species.

44. A semiconductor structure, comprising:

a semiconductor body including at least one contact layer; and

at least one guard ring formed in at least one portion of said contact layer, said guard ring including an implanted region having at least one implanted ion species and that is disposed at least adjacent to a portion of a surface of said contact layer upon which an edge of a Schottky metallic contact is disposed, said implanted region being incompletely annealed.

45. A semiconductor structure as claimed in claim 44 wherein said implanted region adjoins said surface of said contact layer.

46. A semiconductor structure as claimed in claim 44 wherein an end of said implanted region contacts said edge of said Schottky metallic contact.

47. A semiconductor structure as claimed in claim 44 wherein an end of said implanted region is located at an edge of said contact layer.

48. A semiconductor structure as claimed in claim 44 wherein said implanted region is located at least 1 μ

m away from an edge of said contact layer.

49. A semiconductor structure as claimed in claim 48 wherein said implanted region is located at most 10 μ

m away from said edge of said contact layer.

50. A semiconductor structure as claimed in claim 44 wherein an implant dose of said ion species is at least 5E12 cm⁻

2.

51. A semiconductor structure as claimed in claim 44 wherein an implant dose of said ion species is at most 1E16 cm⁻

2.

52. A semiconductor structure as claimed in claim 44 wherein said implanted region is a completely unannealed region.

53. A semiconductor structure as claimed in claim 44 wherein said semiconductor body defines a further surface and includes at least one mesa that projects upwardly from said further surface, said mesa including at least part of said contact layer.

54. A semiconductor structure as claimed in claim 44 wherein said contact layer includes a nitride-based semiconductor.

55. A semiconductor structure as claimed in claim 44 wherein said contact layer includes a gallium nitride-based semiconductor.

56. A semiconductor structure as claimed in claim 44 wherein said contact layer includes GaN.

57. A Schottky junction including a semiconductor structure as claimed in claim 44 and a metallic contact disposed atop at least part of said contact layer to form a Schottky junction therewith.

58. A Schottky diode including a semiconductor structure as claimed in claim 44, said semiconductor body including at least one semiconductor layer formed on a surface of a substrate, said semiconductor layer at least including said contact layer, whereby said semiconductor body includes said substrate and said at least one semiconductor layer;

said Schottky diode further including a metallic contact formed atop at least part of said contact layer to form a Schottky junction therewith.

59. A Schottky diode as claimed in claim 58 further comprising at least one further metallic contact formed on said semiconductor layer in substantially ohmic contact therewith.

60. A Schottky diode as claimed in claim 58 wherein said semiconductor layer includes at least one mesa that projects upwardly from at least one further surface of said semiconductor body, said at least one mesa including said contact layer, said Schottky junction being disposed atop said mesa.

61. A Schottky diode as claimed in claim 60 wherein said further surface of said semiconductor body is a lower contact surface, and said Schottky diode includes at least one further metallic contact formed on said lower contact surface in substantially ohmic contact therewith.

62. A Schottky diode as claimed in claim 60 wherein said semiconductor layer includes a plurality of mesas projecting upwardly from said further surface, at least some of said plurality of mesas each including at least one said guard ring.

63. A Schottky diode as claimed in claim 62 wherein said metallic contact includes a plurality of metallic contacts each disposed atop a respective one of said plurality of mesas and forming a respective Schottky contact with at least a top surface of that mesa.

64. A Schottky diode as claimed in claim 58 wherein said substrate is an electrically insulating material.

65. A Schottky diode as claimed in claim 58 wherein said substrate is a semiconductor, said Schottky diode further including at least one further metallic contact formed on another surface of said substrate in substantially ohmic contact therewith.

66. A Schottky diode including a semiconductor structure as claimed in claim 58, wherein said implanted region is self-aligned to said metallic contact.