US4918509A — Gate turn-off thyristor

Claim 1

Independent Claim 198 words

In a gate turn-off thyristor having an npnp structure formed in a semiconductor body and having a cathode side n±-type emitter zone which is divided into a plurality of emitter strips, with each n + -type emitter strip being opposed by a pair of anode-side p±-type emitter strips which are positioned so as to overlap the respective edges of the respective cathode-side emitter strip, and further having a p-type control base zone and an n-type main base zone disposed between said cathode side and anode side emitter strips, with said n-type main base zone having a higher doped n + -type region which extends along the anode side major surface of said semiconductor body and into which said p + -type emitter strips extend from said anode side major surface; the improvement wherein; a single field limiting lower doped p-type zone is disposed between each said pair of anode side p + -type emitter strips positioned opposite a respective said cathode side emitter strip in said n + -type region at said anode side major surface, and forms a zone which is spaced from each of the adjacent pair of said anode side p + -type emitter strips.

Claim 2

Dependent Claim 198 words

In a gate turn-off thyristor having an npnp structure formed in a semiconductor body and having a cathode side n±-type emitter zone which is divided into a plurality of emitter strips, with each n + -type emitter strip being opposed by a pair of anode-side p±-type emitter strips which are positioned so as to overlap the respective edges of the respective cathode-side emitter strip, and further having a p-type control base zone and an n-type main base zone disposed between said cathode side and anode side emitter strips, with said n-type main base zone having a higher doped n + -type region which extends along the anode side major surface of said semiconductor body and into which said p + -type emitter strips extend from said anode side major surface; the improvement wherein; a single field limiting lower doped p-type zone is disposed between each said pair of anode side p + -type emitter strips positioned opposite a respective said cathode side emitter strip in said n + -type region at said anode side major surface, and forms a zone which is spaced from each of the adjacent pair of said anode side p + -type emitter strips.

Claim 3

Dependent Claim 64 words

A thyristor as defined in claim 1 further comprising: a cathode contact for each said cathode side emitter strip; a gate contact for said control base zone disposed adjacent each said cathode side n-type emitter strip; and an anode contact for said anode side p±-type emitter strips, said field limiting p-type zones, and said n + -type region at said anode side major surface.

Claim 4

Dependent Claim 56 words

A thyristor as defined in claim 1 wherein: said n + -type region of said main base zone p + -type zone at said anode side major surface; and an anode electrode contacts said p + -type emitter strips, said field limiting p-type zones and said n + -type region at said anode side major surface.

Claim 5

Dependent Claim 27 words

A thyristor as defined in claim 3, wherein the width of said field limiting p-type zone is less than that of said p + -type emitter strips.

Claim 6

Dependent Claim 39 words

A thyristor as defined in claim 4 wherein the thickness of said p + -type emitter strips and of said field limiting p-type zones is greater than that of said n + -type region of said main base zone.

Claim 7

Dependent Claim 27 words

A thyristor as defined in claim 5 wherein the thickness of said field limiting p-type zones is less than that of said p + -type emitter strips.

Claim 8

Dependent Claim 36 words

A thyristor as defined in claim 3, wherein the thickness of each said field limiting p-type zone is less than that of said anode-side highly doped n + -type region of said n-type main base zone.

Claim 9

Dependent Claim 49 words

A thyristor as defined in claim 7, wherein the maximum doping concentration of said highly doped n + -type region in front of the central region of said field limiting p-type zone is greater than about 3×10 15 /cm 3 and less than about 1×10 17 /cm 3 .

Claim 10

Dependent Claim 221 words

A gate-turn off thyristor having an npnp structure formed in a semiconductor body and having a cathode side n + -type emitter zone which is divided into a plurality of emitter strips, which each n + -type emitter strip being opposed by a pair of anode-side p + -type emitter strips which are positioned so as to overlap the respective edges of the respective cathode-side emitter strip, and further having a p-type control base zone and an n-type main base zone disposed between said cathode side and anode side emitter strips, with said n-type main base zone having a higher doped n + -type region which extends along the anode side major surface of said semiconductor body and into which said p + -type emitter strips extend from said anode side major surface, and with each said p + -type emitter strip extending through said n + -type region and forming an a p + n junction with said main n-type base zone; the improvement wherein: a field limiting lower-doped p-type zone is disposed within said n + -type region between each said pair of anode side p + -type emitter strips positioned opposite a respective said cathode side emitter strip, with each said field limiting p-type zone extending along said anode-side major surface to the adjacent said p±-type emitter strips.

Claim 11

Dependent Claim 221 words

A gate-turn off thyristor having an npnp structure formed in a semiconductor body and having a cathode side n + -type emitter zone which is divided into a plurality of emitter strips, which each n + -type emitter strip being opposed by a pair of anode-side p + -type emitter strips which are positioned so as to overlap the respective edges of the respective cathode-side emitter strip, and further having a p-type control base zone and an n-type main base zone disposed between said cathode side and anode side emitter strips, with said n-type main base zone having a higher doped n + -type region which extends along the anode side major surface of said semiconductor body and into which said p + -type emitter strips extend from said anode side major surface, and with each said p + -type emitter strip extending through said n + -type region and forming an a p + n junction with said main n-type base zone; the improvement wherein: a field limiting lower-doped p-type zone is disposed within said n + -type region between each said pair of anode side p + -type emitter strips positioned opposite a respective said cathode side emitter strip, with each said field limiting p-type zone extending along said anode-side major surface to the adjacent said p±-type emitter strips.

Claim 12

Dependent Claim 58 words

A thyristor as defined in claim 9, wherein the thickness of said field limiting p-type zone is less than that of said anode-side highly doped n + -type partial zone of said n-type main base zone; and wherein said field limiting p-type zone forms a pn-junction with only said n + -type region of said main base zone.

Claim 13

Dependent Claim 32 words

A thyristor as defined in claim 10, wherein the maximum doping concentration of said highly doped n + -type region is equal to or greater than about 5×10 16 /cm 3 .

Claim 14

Dependent Claim 84 words

A thyristor as defined in claim 11 further comprising: a gate electrode for said control base zone disposed on the cathode side major surface of said semiconductor body adjacent each said cathode side n-type emitter strip; a cathode contact for each said cathode side n-type emitter strip disposed on said cathode side major surface; and an anode contact for said anode side p + -type emitter strips and said field limiting p-type zone disposed on said anode side major surface of said semiconductor body.

Claim 15

Dependent Claim 27 words

A thyristor as defined in claim 12 wherein, an anode-side p-type zone is disposed in the regions below said gate contact along said anode side major surface.

Claim 16

Dependent Claim 28 words

A thyristor as defined in claim 7 wherein the thickness of each said field limiting p-type zone is less than that of said p + -type emitter strips.

Claim 17

Dependent Claim 28 words

A thyristor as defined in claim 14 wherein said width of each said field limiting p-type zone is less than that of said p + -type emitter strips.

Claim 18

Dependent Claim 229 words

In a gate turn-off thyristor having an npnp structure formed in a semiconductor body and having a cathode side n + -type emitter zone which is divided into a plurality of emitter strips, with each n + -type emitter strip being opposed by a pair of anode-side p-type emitter strips which are positioned so as to overlap the respective edges of the respective cathode-side emitter strip, and further having a p-type control base zone and an n-type main base zone disposed between said cathode side and anode side emitter strips, with said n-type main base zone having a higher doped n + -type region which extends along the anode side major surface of said semiconductor body and into which said p-type emitter strips extend from said anode side major surface; the improvement comprising means, including a single p-type zone disposed between each said pair of anode side p-type emitter strips positioned opposite a respective said cathode side emitter strip and at said anode side major surface, for injecting holes to a lesser degree than the adjacent said pair of anode side p-type emitter strips into said n-type main base zone essentially only during displacement of the space charge zone occurring in the non-regenerative transistor region of the thyristor below the respective said cathode-side emitter strip during turn-off of high currents by the thyristor to dynamically limit the electrical field.

Claim 19

Dependent Claim 229 words

In a gate turn-off thyristor having an npnp structure formed in a semiconductor body and having a cathode side n + -type emitter zone which is divided into a plurality of emitter strips, with each n + -type emitter strip being opposed by a pair of anode-side p-type emitter strips which are positioned so as to overlap the respective edges of the respective cathode-side emitter strip, and further having a p-type control base zone and an n-type main base zone disposed between said cathode side and anode side emitter strips, with said n-type main base zone having a higher doped n + -type region which extends along the anode side major surface of said semiconductor body and into which said p-type emitter strips extend from said anode side major surface; the improvement comprising means, including a single p-type zone disposed between each said pair of anode side p-type emitter strips positioned opposite a respective said cathode side emitter strip and at said anode side major surface, for injecting holes to a lesser degree than the adjacent said pair of anode side p-type emitter strips into said n-type main base zone essentially only during displacement of the space charge zone occurring in the non-regenerative transistor region of the thyristor below the respective said cathode-side emitter strip during turn-off of high currents by the thyristor to dynamically limit the electrical field.

Claim 20

Dependent Claim 28 words

A thyristor as defined in claim 16 wherein the doping concentration of each said single p-type zone is less than that of said anode side p-type emitter strips.

Claim 21

Dependent Claim 29 words

A thyristor as defined in claim 16, wherein each said single p-type zone is laterally spaced from each of the adjacent pair of said anode side p-type emitter strips.

Claim 22

Dependent Claim 24 words

A thyristor as defined in claim 18, wherein the width of said single p-type zones is less than that of said p-type emitter strips.

Claim 23

Dependent Claim 27 words

A thyristor as defined in claim 18, wherein the thickness of said single p-type zones is less than that of said higher doped n + -type region.

Claim 24

Dependent Claim 49 words

A thyristor as defined in claim 20, wherein the maximum doping concentration of said higher doped n + -type region in front of a central region of each said single p-type zone is greater than approximately 3×10 15 /cm 3 and less than approximately 1×10 17 /cm 3 .

Claim 25

Dependent Claim 26 words

A thyristor as defined in claim 16, wherein each said single p-type zone extends along said anode-side major surface to the adjacent said p-type emitter strips.

Claim 26

Dependent Claim 52 words

A thyristor as defined in claim 22 wherein: each said single p-type zone has a thickness less than that of said higher doped n + -type region; and the maximum doping concentration of said higher doped n + -type region is equal to or greater than approximately 5×10 16 /cm 3 .

Claim 27

Dependent Claim 137 words

A thyristor as defined in claim 22, wherein each said single p-type zone has a doping concentration and a thickness less than that of said anode side p-type emitter strips; and further comprising: a gate electrode for said control base zone disposed on the cathode side major surface of said semiconductor body adjacent each said cathode side n-type emitter strip; a cathode contact for each said cathode side n-type emitter strip disposed on said cathode side major surface; an anode contact for said anode side p-type emitter strips and said single p-type zones disposed on said anode side major surface of said semiconductor body; and further anode side p-type zones disposed in the regions below said gate contact and extending from said anode side p-type emitter strips along said anode side major surface of said semiconductor body.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1993-04-16	1993-10-16	1994-04-17	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1997-04-16	1997-10-16	1998-04-17	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2001-04-16	2001-10-16	2002-04-17	$7700.00	Window Closed / Lapsed

Gate turn-off thyristor

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