Overvoltage self-protection semiconductor device, method of fabrication thereof and semiconductor circuit using the same

• US 5,627,387 A
• Filed: 03/01/1995
• Issued: 05/06/1997
• Est. Priority Date: 12/26/1991
• Status: Expired due to Term

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Murakami, Susumu, Mochizuki, Yasuhiro, Shimizu, Yoshiteru, Yokota, Takeshi
• Primary Examiner(s): CARROLL, JAMES J
• Application Number:
  US08/396,259
• Time in Patent Office: 797 Days
• Field of Search: 257/127, 257/132, 257/167, 257/168, 257/170, 257/172, 257/173, 437/6
• US Class Current: 257/173
• CPC Class Codes: H01L 29/0626 with a localised breakdown region, e.g. built-in avalanching region in self-protected thyristors H01L29/7424
• CPC Class Codes: H01L 29/7424 having a built-in localised breakdown/breakover region, e.g. self-protected against destructive spontaneous, e.g. voltage breakover, firing
• CPC Class Codes: H01L 29/7428 having an amplifying gate structure, e.g. cascade (Darlington) configuration
• CPC Class Codes: H01L 29/87 Thyristor diodes, e.g. Shockley diodes, break-over diodes

Abstract

A novel semiconductor device with a pair of main surfaces is disclosed, in which at least three semiconductor layers are formed adjacently to each other. The device comprises a main thyristor portion for supplying a main current, an auxiliary thyristor portion, a pilot thyristor portion and a breakover portion. The breakover portion, in turn, includes a semiconductor layer having a high impurities concentration formed on one of the main surfaces, and a plurality of semiconductor layers having a high impurities concentration of opposite conduction type formed adjacently to the semiconductor layer and in spaced relationship from each other.

Claims

1. An overvoltage self-protection semiconductor device comprising a thyristor portion and an overvoltage protection portion:

said thyristor portion including;

a first semiconductor layer of first conductivity type formed in a semiconductor substrate;

a second semiconductor layer of second conductivity type formed on one of main surfaces of said semiconductor substrate adjacently to one of the surfaces of said first semiconductor layer;

a third semiconductor layer of second conductivity type adjacent to another surface of said first semiconductor layer;

a plurality of fourth semiconductor layers of first conductivity type formed in spaced relationship with each other on said third semiconductor layer;

a first electrode formed on said second semiconductor layer; and

a second electrode formed on said third semiconductor layer and said fourth semiconductor layers;

said overvoltage protection portion including;

said first semiconductor layer;

said second semiconductor layer;

said third semiconductor layer;

a fifth semiconductor layer of first conductivity type having a high impurities concentration formed on said third semiconductor layer; and

a sixth semiconductor layer of second conductivity type having a high impurities concentration formed on said third semiconductor layer adjacent to said fifth semiconductor layer to form a pn junction between said fifth and sixth semiconductor layers, said sixth semiconductor layer bridging said fifth semiconductor layer and one of said fourth semiconductor layers;

wherein the breakover voltage of said overvoltage protection portion is lower than that of the thyristor portion, and

wherein said fifth semiconductor layer of the overvoltage protection portion is spaced apart from a main junction between the first and third semiconductor layers by a predetermined distance so that when a predetermined overvoltage is applied to said first electrode and said second electrode, a depletion layer extending from said main junction due to the overvoltage will punch through the third semiconductor layer to the fifth semiconductor layer to provide overvoltage protection to the main device.

2. An overvoltage self-protection semiconductor device according to claim 1, wherein:

when an overvoltage is applied to said first electrode and said second electrode, the pn junction formed between said fifth semiconductor layer and said sixth semiconductor layer is subjected to a selected one of avalanche breakdown and zener breakdown.

3. An overvoltage self-protection semiconductor device comprising a thyristor portion and an overvoltage protection portion:

said thyristor portion including;

a first semiconductor layer of first conductivity type formed in a semiconductor substrate;

a second semiconductor layer of second conductivity type formed on one of main surfaces of said semiconductor substrate adjacently to one of the surfaces of said first semiconductor layer;

a third semiconductor layer of second conductivity type adjacent to another surface of said first semiconductor layer;

a plurality of fourth semiconductor layers of first conductivity type formed in spaced relationship with each other on said third semiconductor layer;

a first electrode formed on said second semiconductor layer; and

a second electrode formed on said third semiconductor layer and said fourth semiconductor layers;

said overvoltage protection portion including;

said first semiconductor layer;

said second semiconductor layer;

said third semiconductor layer;

a fifth semiconductor layer of first conductivity type having a high impurities concentration formed on said third semiconductor layer; and

a sixth semiconductor layer of second conductivity type having a high impurities concentration formed on said third semiconductor layer adjacent to said fifth semiconductor layer to form a pn junction between said fifth and sixth semiconductor layers, said sixth semiconductor layer bridging said fifth semiconductor layer and one of said fourth semiconductor layers;

wherein a thickness of the third semiconductor layer directly under the fifth semiconductor layer is smaller than that of the third semiconductor layer directly under the fourth semiconductor layer, and

wherein said fifth semiconductor layer of the overvoltage protection portion is spaced apart from a main junction between the first and third semiconductor layers by a predetermined distance so that when a predetermined overvoltage is applied to said first electrode and said second electrode, a depletion layer extending from said main junction due to the overvoltage will punch through the third semiconductor layer to the fifth semiconductor layer to provide overvoltage protection to the device.

4. An overvoltage self-protection semiconductor device according to claim 3,

wherein when an overvoltage is applied to said first electrode and said second electrode, the pn junction formed between said fifth semiconductor layer and said sixth semiconductor layer is subjected to a selected one of avalanche breakdown and zener breakdown.

5. An overvoltage self-protection semiconductor device comprising a thyristor portion and an overvoltage protection portion:

said thyristor portion including;

a first semiconductor layer of first conductivity type formed in a semiconductor substrate;

a second semiconductor layer of second conductivity type formed on one of main surfaces of said semiconductor substrate adjacently to one of the surfaces of said first semiconductor layer;

a third semiconductor layer of second conductivity type adjacent to another surface of said first semiconductor layer;

a plurality of fourth semiconductor layers of first conductivity type formed in spaced relationship with each other on said third semiconductor layer;

a first electrode formed on said second semiconductor layer; and

a second electrode formed on said third semiconductor layer and said fourth semiconductor layers;

said overvoltage protection portion including;

said first semiconductor layer;

said second semiconductor layer;

said third semiconductor layer;

a fifth semiconductor layer of first conductivity type having a high impurities concentration formed on said third semiconductor layer; and

a sixth semiconductor layer of second conductivity type having a high impurities concentration formed on said third semiconductor layer adjacent to said fifth semiconductor layer to form a pn junction between said fifth and sixth semiconductor layers, said sixth semiconductor layer bridging said fifth semiconductor layer and one of said fourth semiconductor layers,

wherein said fifth semiconductor layer of the overvoltage protection portion is spaced apart from a main junction between the first and third semiconductor layers by a predetermined distance so that when a predetermined overvoltage is applied to said first electrode and said second electrode, a depletion layer extending from said main junction due to the overvoltage will punch through the third semiconductor layer to the fifth semiconductor layer to provide overvoltage protection to the device.

6. An overvoltage self-protection semiconductor device according to claim 5,

wherein when an overvoltage is applied to said first electrode and said second electrode, the pn junction formed between said fifth semiconductor layer and said sixth semiconductor layer is subjected to a selected one of avalanche breakdown and zener breakdown.

7. An overvoltage self-protection semiconductor device comprising a thyristor portion, an auxiliary thyristor portion and an overvoltage protection portion:

said thyristor portion including;

a first semiconductor layer of first conductivity type formed in a semiconductor substrate;

a second semiconductor layer of second conductivity type formed on one of main surfaces of said semiconductor substrate adjacently to one of the surfaces of said first semiconductor layer;

a third semiconductor layer of second conductivity type adjacent to another surface of said first semiconductor layer;

a plurality of fourth semiconductor layers of first conductivity type formed in spaced relationship with each other on said third semiconductor layer;

a first electrode formed on said second semiconductor layer; and

a second electrode formed on said third semiconductor layer and said fourth semiconductor layers;

said auxiliary thyristor portion including;

said first semiconductor layer;

said second semiconductor layer;

said third semiconductor layer;

a fifth semiconductor layer of first conductivity type formed in spaced relationship with said fourth semiconductor layers on said third semiconductor layer; and

a third electrode formed on said third semiconductor layer and said fifth semiconductor layer;

said overvoltage protection portion including;

said first semiconductor layer;

said second semiconductor layer;

said third semiconductor layer;

a sixth semiconductor layer of first conductivity type having a high impurities concentration formed on said third semiconductor layer; and

a seventh semiconductor layer of second conductivity type having a high impurities concentration formed on said third semiconductor layer adjacent to said sixth semiconductor layer to form a pn junction between said sixth and seventh semiconductor layers, said seventh semiconductor layer bridging said sixth semiconductor layer and said fifth semiconductor layer,

wherein said sixth semiconductor layer of the overvoltage protection portion is spaced apart from a main junction between the first and third semiconductor layers by a predetermined distance so that when a predetermined overvoltage is applied to said first electrode and said second electrode, a depletion layer extending from said main junction due to the overvoltage will punch through the third semiconductor layer to the sixth semiconductor layer to provide overvoltage protection to the device.

8. An overvoltage self-protection semiconductor device according to claim 7,

wherein when an overvoltage is applied to said first electrode and said second electrode, said auxiliary thyristor portion is turned on by a selected one of avalanche breakdown and zener breakdown caused in the pn junction formed between said seventh semiconductor layer and said sixth semiconductor layer.

9. An overvoltage self-protection semiconductor device comprising a thyristor portion and an overvoltage protection portion:

said thyristor portion including;

a first semiconductor layer of first conductivity type formed in a semiconductor substrate;

a second semiconductor layer of second conductivity type formed on one of main surfaces of said semiconductor substrate adjacently to one of the surfaces of said first semiconductor layer;

a third semiconductor layer of second conductivity type adjacent to another surface of said first semiconductor layer;

a plurality of fourth semiconductor layers of first conductivity type formed in spaced relationship with each other on said third semiconductor layer;

a first electrode formed on said second semiconductor layer; and

a second electrode formed on said third semiconductor layer and said fourth semiconductor layers;

said overvoltage protection portion including;

said first semiconductor layer;

said second semiconductor layer;

said third semiconductor layer;

a well region formed in said third semiconductor layer and an island region formed in said well region;

a fifth semiconductor layer of first conductivity type having a high impurities concentration formed in said well region;

a sixth semiconductor layer of second conductivity type having a high impurities concentration formed in a peripheral region of said well region adjacent to said fifth semiconductor layer to form a pn junction between said fifth and sixth semiconductor layers, said sixth semiconductor layer bridging said fifth semiconductor layer and one of said fourth semiconductor layers; and

a seventh semiconductor layer of second conductivity type having a high impurities concentration formed in said island region,

wherein said fifth semiconductor layer of the overvoltage protection portion is spaced apart from a main junction between the first and third semiconductor layers by a predetermined distance so that when a predetermined overvoltage is applied to said first electrode and said second electrode, a depletion layer extending from said main junction due to the overvoltage will punch through the third semiconductor layer to the fifth semiconductor layer to provide overvoltage protection to the device.

10. An overvoltage self-protection semiconductor device according to claim 9,

wherein when an overvoltage is applied to said first electrode and said second electrode, the pn junction formed between said fifth semiconductor layer and said sixth semiconductor layer is subjected to a selected one of avalanche breakdown and zener breakdown.

11. An overvoltage self-protection semiconductor device comprising:

a first semiconductor region of first conductivity type formed in a semiconductor substrate;

a second semiconductor region of second conductivity type formed adjacently to said first semiconductor region;

a third semiconductor region of second conductivity type formed in a form of a well in said first semiconductor region;

a fourth semiconductor region of first conductivity type formed in a form of a well in said third semiconductor region;

a fifth semiconductor region of first conductivity type having a high impurities concentration formed in said third semiconductor region;

a sixth semiconductor region of second conductivity type having a high impurities concentration formed adjacently to said fifth semiconductor region in said third semiconductor region to form a pn junction with said fifth semiconductor region;

a first electrode formed on said second semiconductor region; and

a second electrode formed on said fourth semiconductor region;

wherein the fifth semiconductor region is spaced apart from a main junction between the first and third semiconductor regions by a predetermined distance so that when a predetermined overvoltage is applied to the first and second electrodes, a depletion layer extending from said main junction will punch through said third semiconductor region to said fifth semiconductor region to provide overvoltage protection for the semiconductor device.

12. An overvoltage self-protection semiconductor device according to claim 11,

wherein when said predetermined overvoltage is applied to said first electrode and said second electrode, the pn junction formed between said fifth semiconductor region and said sixth semiconductor region is subjected to a selected one of avalanche breakdown and zener breakdown.

13. An overvoltage self-protection semiconductor device with a pair of main surfaces, comprising a thyristor portion including at least first, second and third semiconductor layers formed adjacently to each other for supplying a main current between first and second electrodes and a breakover portion;

wherein said breakover portion includes a fourth semiconductor layer of a first conductivity type having a high impurities concentration formed in one of the main surfaces and a plurality of fifth semiconductor layers having a high impurities concentration of a second conductivity type formed to be isolated by said first semiconductor layer, wherein said plurality of fifth semiconductor layers form pn junctions with said fourth semiconductor layer,

wherein said second electrode is coupled to said first and second semiconductor layers, and wherein a main junction between said second and third semiconductor layers of said thyristor portion and said fourth semiconductor layer of said breakdown portion are spaced apart from one another by a predetermined distance so that when a predetermined overvoltage is applied between said first and second electrodes to said thyristor portion, a depletion layer extending from said main junction will punch through to said fourth semiconductor layer to provide overvoltage protection for said semiconductor device.

14. An overvoltage self-protection semiconductor device according to claim 13, further comprising an auxiliary thyristor portion and a pilot thyristor portion,

wherein a depletion layer extending to a semiconductor layer formed in a lower portion of said fourth semiconductor layer having a high impurities concentration is brought into contact with another depletion layer in thermal equilibrium on a pilot thyristor side of a junction of semiconductor layers having a high impurities concentration of opposite conductivity types to one another after contacting a lower surface of said fourth semiconductor layer having a high impurities concentration, whereby said breakover portion is subjected to selected one of avalanche and zener breakdown.

15. A semiconductor circuit comprising a plurality of overvoltage self-protection semiconductor devices according to claim 13 for converting AC power into DC power.

16. A semiconductor circuit comprising a plurality of overvoltage self-protection semiconductor devices according to claim 13 for converting DC power into AC power.

17. A semiconductor circuit comprising a plurality of overvoltage self-protection semiconductor devices according to claim 13 for converting AC power of first frequency into AC power of second frequency.

18. A semiconductor circuit comprising a plurality of overvoltage self-protection semiconductor devices according to claim 13 for compensating reactive power.

19. A semiconductor circuit system comprising a plurality of semiconductor circuits according to claim 15 for effecting high-voltage DC transmission.

20. An overvoltage self-protection semiconductor device with a pair of main surfaces, comprising at least three adjacent semiconductor layers including a plurality of first semiconductor layers having a high impurities concentration of first conductivity type formed in spaced relationship with each other on a surface of a second semiconductor layer adjacent to a lower portion of the first semiconductor layers at one of the main surfaces, a third semiconductor layer of a first conductivity type adjacent to a lower surface of said second semiconductor layer, and a fourth semiconductor layer of second conductivity type, said first, second, third and fourth semiconductor layers being formed sequentially, a first electrode being formed on at least one of said first semiconductor layers, and a second electrode being formed on said fourth semiconductor layer,

wherein said overvoltage self-protection semiconductor device includes an overvoltage protection portion including at least one of said first semiconductor layers which does not have said first electrode formed thereon, said at least one of said first semiconductor layers and said second semiconductor layer making up a pn junction portion having a potential barrier, and wherein a plurality of portions are provided adjacent to said pn junction portion, wherein said plurality of portions do not have said first electrode formed thereon, and wherein said plurality of portions provide regions having a high impurities concentration in the surface of the second semiconductor layer at said one of said main surfaces.

21. An overvoltage self-protection semiconductor device according to claim 20, wherein a first structure comprised the portion of the first semiconductor layers, which portion does not have the first electrode formed thereon, the second, third and fourth semiconductor layers have a lower breakdown voltage than a breakdown voltage of a second structure comprised of the rest of the first semiconductor layers which have the first electrode formed thereon, and the second, third and fourth semiconductor layers, wherein a depletion layer extending into the second semiconductor layer reaches the portion of said first semiconductor layers at said lower breakdown voltage, and wherein an electric field intensity is higher in the pn junction portion having a potential barrier including said portion of said first semiconductor layers on which the first electrode is not formed and a selected one of a fifth semiconductor layer having a high impurity concentration and said region of the second semiconductor layer having the high impurities concentration formed in the one of the main surfaces than that of the rest of the first semiconductor layers, thereby causing a breakdown.

22. An overvoltage self-protection semiconductor device according to claim 20, wherein at least one of said first semiconductor layers and said second semiconductor layer have a portion electrically connected at the first electrode.

23. An overvoltage self-protection semiconductor device with a pair of main surfaces, comprising at least three adjacent semiconductor layers including a plurality of first semiconductor layers having a high impurities concentration of first conductivity type isolated from each other on one surface of a second semiconductor layer adjacent to a lower portion of the plurality of first semiconductor layers, a third semiconductor layer of first conductivity type adjacent to a lower surface of the second semiconductor layer and a fourth semiconductor layer of second conductivity type, said semiconductor layers being formed sequentially, said device further comprising a first electrode formed on at least one of said first semiconductor layers and a second electrode formed on said fourth semiconductor layer,

wherein at least another one of said first semiconductor layers includes a portion not having the first electrode formed thereon, and wherein a pn junction having a potential barrier including at least the another one of the first semiconductor layers and the second semiconductor layer has a plurality of fifth semiconductor layers having a high impurities concentration of second conductivity type formed in isolation from each other adjacently to said portion of said at least the another one of the first semiconductor layers not having the first electrode formed thereon.

24. An overvoltage self-protection semiconductor device according to claim 23, wherein a first structure comprises the portion of the first semiconductor layers, which portion does not have the first electrode formed thereon, the second, third and fourth semiconductor layers have a lower breakdown voltage than a breakdown voltage of a second structure comprised of the rest of the first semiconductor layers which have the first electrode formed thereon, and the second, third and fourth semiconductor layers, wherein a depletion layer extending into the second semiconductor layer reaches the portion of said first semiconductor layers at said lower breakdown voltage, and wherein an electric field intensity is higher in the pn junction portion having a potential barrier including said portion of said first semiconductor layers on which the first electrode is not formed and a selected one of a fifth semiconductor layer having a higher impurity concentration than that of the rest of the first semiconductor layers, thereby causing a breakdown.

25. An overvoltage self-protection semiconductor device according to claim 23, wherein at least one of said first semiconductor layers and said second semiconductor layer have a portion electrically connected to the first electrode.