SEMICONDUCTOR DEVICE

• US 20170084701A1
• Filed: 12/01/2016
• Published: 03/23/2017
• Est. Priority Date: 12/25/2014
• Status: Active Grant

• Current Assignee: Fuji Electric Company Limited (Fuji Electric Systems Company Limited)
• Original Assignee: Fuji Electric Company Limited (Fuji Electric Systems Company Limited)
• Inventors: Kitamura, Shoji
• Granted Patent: US 10,374,043 B2
• Time in Patent Office: Days
• CPC Class Codes: H01L 21/0465 using masks
• 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 29/0623 Buried supplementary region, e.g. buried guard ring multi-RESURF H01L29/0634
• CPC Class Codes: H01L 29/1608 Silicon carbide
• CPC Class Codes: H01L 29/36 characterised by the concentration or distribution of impurities in the bulk material within semiconductor regions H01L29/06
• CPC Class Codes: H01L 29/6606 the devices being controllable only by variation of the electric current supplied or the electric potential applied, to one or more of the electrodes carrying the current to be rectified, amplified, oscillated or switched, e.g. two-terminal devices
• CPC Class Codes: H01L 29/8611 Planar PN junction diodes
• CPC Class Codes: H01L 29/872 Schottky diodes

Abstract

In an edge termination structure portion, first and second JTE regions are disposed concentrically surrounding an active region. Between the first and second JTE regions, a p-type electric field relaxation region is disposed that includes a first subregion and a second subregion alternately and repeatedly arranged concentrically surround a periphery of the first JTE region. An average impurity concentration of the electric field relaxation region is higher that the impurity concentration of the first JTE region adjacent on the inner side and lower than the impurity concentration of the second JTE region adjacent on the outer side. First subregions have widths that decrease the farther outward they are arranged. Second subregions have widths that are substantially the same independent of position. The first subregions and the first JTE region have equal impurity concentrations. The second subregions and the second JTE region have equal impurity concentrations.

Claims

1. A semiconductor device comprising:

a semiconductor substrate of a first conductivity type, formed of a silicon carbide semiconductor;

an active region disposed on a front surface of the semiconductor substrate and through which a main current flows, the active region having a periphery; and

an edge termination structure surrounding a periphery of the active region, wherein

the edge termination structure includes;

a plurality of semiconductor regions of a second conductivity type, disposed concentrically surrounding the periphery of the active region, each semiconductor region having a lower impurity concentration the further the semiconductor region is from the periphery, and

an intermediate region of the second conductivity type, disposed so as to mutually contact adjacent ones of the plurality of semiconductor regions, the intermediate region having an impurity concentration that is lower than that of the adjacent semiconductor region on a side closer to the periphery and an impurity concentration that is higher than that of the adjacent semiconductor region on a side further from the periphery,

the intermediate region includes a first subregion of the second conductivity type and a second subregion of the second conductivity type, the second subregion having an impurity concentration that is lower than that of the first subregion, a plurality of the first and second subregions being alternately and repeatedly arranged concentrically surrounding the adjacent semiconductor region on the side closer to the periphery of the active region,

the plurality of second subregions having a same width, and

the plurality of first subregions having respective widths that are narrower the farther from the periphery of the active region the first subregions are arranged.

2. The semiconductor device according to claim 1, each intermediate region further comprising

a third subregion disposed outermost from the periphery of the active region in the intermediate region and having an impurity concentration that is lower than that of the first subregion and an impurity concentration that is higher than that of the adjacent semiconductor region on a side further from the periphery.

3. The semiconductor device according to claim 2, wherein

the third subregion includes a first portion of the second conductivity type having an impurity concentration that is lower than that of the first subregion, selectively disposed in a first region of an electric field relaxation region arranged outermost from the periphery of the active region in the intermediate region.

4. The semiconductor device according to claim 3, wherein

the third subregion includes along a direction of a border of the active region and the edge termination structure portion, ones of the first subregion and the first portion being alternately and repeatedly arranged.

5. The semiconductor device according to claim 1, further comprising

a fourth subregion disposed innermost to the periphery of the active region in each intermediate region and having an impurity concentration that is lower than that of an adjacent one of the semiconductor regions on a side closer to the periphery of the active region and an impurity concentration that is higher than that of the second subregion.

6. The semiconductor device according to claim 5, wherein

the fourth subregion includes a second portion of the second conductivity type having an impurity concentration that is higher than that of the second subregion, selectively disposed in the second subregion arranged innermost to the periphery of the active region in each intermediate region.

7. The semiconductor device according to claim 6, wherein

the fourth subregion includes along a direction of a border of the active region and the edge termination structure, a plurality of the second subregions and the second portions being alternately and repeatedly arranged.

8. The semiconductor device according to claim 1, wherein

the second subregion is arranged innermost to the periphery of the active region in each intermediate region, and

the first subregion is arranged outermost from the periphery of the active region in each intermediate region.

9. The semiconductor device according to claim 1, each intermediate region further comprising

a fifth subregion disposed between adjacent ones of the first subregion and the second subregion, the fifth subregion having an impurity concentration that is lower than that of the adjacent first subregion and an impurity concentration that is higher than that of the adjacent second subregion.

10. The semiconductor device according to claim 9, wherein

the fifth subregion includes a third portion of the second conductivity type having an impurity concentration that is lower than that of the adjacent first subregion, selectively disposed in the adjacent first subregion.

11. The semiconductor device according to claim 10, wherein

the fifth subregion includes along a direction of a border of the active region and the edge termination structure portion, a plurality of first subregions and third portions alternately and repeatedly arranged.

12. The semiconductor device according to claim 10, wherein

the third portion is disposed proximate an interface of adjacent ones of the first subregion and the second subregion on an outer side of the first subregion from the periphery of the active region.

34. The semiconductor device according to claim 3, wherein

the first portion has an impurity concentration that is a same as that of the adjacent one of the plurality of semiconductor regions on an outer side of the first portion relative to the periphery of the active region.

35. The semiconductor device according to claim 6, wherein

the second portion has an impurity concentration that is a same as that of the adjacent one of the plurality of semiconductor regions on the side of the second portion closer to the periphery of the active region.

36. The semiconductor device according to claim 10, wherein

the third portion has an impurity concentration that is a same as that of the adjacent one of the plurality of semiconductor regions on a side further from the third portion.

37. The semiconductor device according to claim 1, wherein

the first subregion has an impurity concentration that is a same as that of the adjacent one of the plurality of semiconductor regions on a side of the first subregion closer to the periphery of the active region.

38. The semiconductor device according to claim 1, wherein

the second subregion has an impurity concentration that is a same as that of the adjacent one of the plurality of semiconductor regions on a side of the second subregion further from the periphery of the active region.

39. The semiconductor device according to claim 1, wherein

the intermediate region has an average impurity concentration that is intermediate between an impurity concentration of an adjacent one of the semiconductor regions on a side closer to the periphery of the active region and an adjacent one of the semiconductor regions on a side further from the periphery of the active region.

13. A semiconductor device comprising:

a semiconductor substrate of a first conductivity type, formed of a silicon carbide semiconductor;

an active region disposed on a front surface of the semiconductor substrate and through which a main current flows, the active region having a periphery; and

an edge termination structure surrounding the periphery of the active region, wherein

the edge termination structure includes;

a plurality of semiconductor regions disposed concentrically surrounding the periphery of the active region, the plurality of semiconductor regions having a lower impurity concentration the further each of the plurality of semiconductor regions is from the periphery of the active region, and

an intermediate region of the second conductivity type, disposed so as to mutually contact adjacent ones of the plurality of semiconductor regions, the intermediate region having an impurity concentration that is lower than that of the adjacent semiconductor region on a side closer to the periphery of the active region and an impurity concentration that is higher than that of the semiconductor region adjacent on a side further from the periphery of the active region,

the intermediate region is divided into a plurality of sections concentrically surrounding the adjacent semiconductor region on a side closer to the periphery of the active region,

a plurality of first subregions of the second conductivity type and a plurality of second subregions of the second conductivity type, the second subregions having an impurity concentration that is lower than that of the first subregion, alternately and repeatedly arranged, are disposed concentrically in the sections from an inner side toward an outer side relative to the periphery of the active region,

a microregion including adjacent ones of the first subregion and the second subregion having a same width in a same section of the sections and having a width that is narrower the farther outward a section is positioned in which the microregion is arranged.

14. The semiconductor device according to claim 13, wherein

the microregion has an average impurity concentration N_p satisfying the following equation:

N_p=((x₁×

n_p1)+(x₂×

n_p2))/(x₁+x₂)

where, the width and the impurity concentration of the first subregion are x₁ and n_p1, respectively, and the width and the impurity concentration of the second subregion are x₂ and n_p2, respectively.

15. The semiconductor device according to claim 13, wherein

the plurality of second subregions have the same width.

16. The semiconductor device according to claim 13, wherein

the width of the plurality of first subregions is narrower the farther outward each one of the plurality of first subregions is arranged.

17. The semiconductor device according to claim 13, wherein

a one of the plurality of first subregions arranged outermost from the periphery of the active region has a width that is a smallest size formable by manufacture processing.

18. The semiconductor device according to claim 13, further comprising

a first portion of the second conductivity type, selectively disposed in a one of the plurality of first subregions arranged in the section positioned outermost from the periphery of the active region, the first portion having an impurity concentration that is lower than that of an adjacent one of the plurality of first subregions.

19. The semiconductor device according to claim 13, further comprising

a first portion of the second conductivity type, selectively disposed in the one of the plurality of first subregions, having an impurity concentration that is lower than that of the adjacent one of the plurality of first subregions, wherein

a ratio of an area of the first portion and an area of the first subregion is higher the farther outward the one of the plurality of first subregions is arranged.

20. The semiconductor device according to claim 18, wherein

the first portion is arranged at a predetermined interval along a direction of a border of the active region and the edge termination structure.

21. The semiconductor device according to claim 13, further comprising

a second portion of the second conductivity type, selectively disposed in a one of the plurality of second subregions arranged in the section positioned innermost to the periphery of the active region, the second portion having an impurity concentration that is higher than that of the one of the plurality of second subregions.

22. The semiconductor device according to claim 13, further comprising

a second portion of the second conductivity type, selectively disposed in a one of the plurality of second subregions, and having an impurity concentration that is higher than that of the one of the plurality of second subregions, wherein

a ratio of an area of the second portion and an area of the one of the plurality of second subregions is lower the farther outward the one of the plurality of second subregions is arranged.

23. The semiconductor device according to claim 21, wherein

the second portion is disposed at a predetermined interval along a direction of a border of the active region and the edge termination structure.

40. The semiconductor device according to claim 13, wherein

the intermediate region has an average impurity concentration that is intermediate between an impurity concentration of an adjacent one of the semiconductor regions on a side closer to the periphery of the active region and an adjacent one of the semiconductor regions on a side further from the periphery of the active region.

24. A semiconductor device comprising:

a semiconductor substrate of a first conductivity type, formed of a silicon carbide semiconductor;

an active region disposed on a front surface of the semiconductor substrate and through which main current flows, the active region having a periphery; and

an edge termination structure surrounding a periphery of the active region, wherein

the edge termination structure includes;

a plurality of semiconductor regions disposed concentrically surrounding a periphery of the active region, the farther outward a semiconductor region thereamong is arranged, the lower an impurity concentration thereof is, and

an intermediate region disposed so as to mutually contact adjacent ones of the plurality of semiconductor regions, the intermediate region having an impurity concentration that is lower than that of the adjacent semiconductor region on a side closer to the periphery of the active region and an impurity concentration that is higher than that of the adjacent semiconductor region on a side further from the active region,

the intermediate region is divided into a plurality of sections concentrically surrounding the adjacent semiconductor region on a side closer to the periphery of the active region,

a plurality of first subregions of the second conductivity type and a plurality of second subregions of the second conductivity type, the plurality of second subregions of the second conductivity type having an impurity concentration that is lower than that of the plurality of first subregions of the second conductivity type, alternately and repeatedly arranged, are disposed concentrically in the sections from an inner side toward an outer side relative to the periphery of the active region,

each of the plurality of sections has an average impurity concentration determined based on widths of the plurality of first subregions and the plurality of second subregions arranged in the said section, where the average impurity concentration is lower the farther outward the said section is arranged relative to the periphery of the active region, and

an average impurity concentration difference between all adjacent sections is equal.

25. The semiconductor device according to claim 24, wherein

a microregion including adjacent ones of the plurality of first subregions and the plurality of second subregions has an average impurity concentration equal to the average impurity concentration of the section in which the microregion is arranged.

26. The semiconductor device according to claim 25, wherein

the microregion has an average impurity concentration N_p satisfying the following equation:

N_p=((x₁×

n_p1)+(x₂×

n_p2))/(x₁+x₂)

where, the width and the impurity concentration of the first subregion are x₁ and n_p1, respectively, and the width and the impurity concentration of the second subregion are x₂ and n_p2, respectively.

27. The semiconductor device according to claim 25, wherein

the microregion is disposed at a same interval in a same section of the plurality of sections.

28. The semiconductor device according to claim 24, wherein

the innermost section of the plurality of sections has an average impurity concentration that is 90 percent or more of the average impurity concentration of the semiconductor region adjacent on the inner side of the section relative to the periphery of the active region.

29. The semiconductor device according to claim 24, wherein

the intermediate region has an average impurity concentration slope that is constant across the intermediate region entirely.

30. The semiconductor device according to claim 24, further comprising

a first portion of the second conductivity type, selectively disposed in a one of the plurality of first subregions arranged in the section positioned outermost relative to the periphery of the active region, the first portion having an impurity concentration that is lower than that of the one of the plurality of first subregions.

31. The semiconductor device according to claim 30, wherein

the first portion is arranged at a predetermined interval along a direction of a border of the active region and the edge termination structure.

32. The semiconductor device according to claim 24, further comprising

a second portion of the second conductivity type, selectively disposed in a one of the plurality of second subregions arranged in the section positioned innermost relative to the periphery of the active region, the second portion having an impurity concentration that is higher than that of the one of the plurality of second subregions.

33. The semiconductor device according to claim 32, wherein

the second portion is arranged at a predetermined interval along a direction of a border of the active region and the edge termination structure.

41. The semiconductor device according to claim 24, wherein

the intermediate region has an average impurity concentration that is intermediate between an impurity concentration of an adjacent one of the semiconductor regions on a side closer to the periphery of the active region and an adjacent one of the semiconductor regions on a side further from the periphery of the active region.