Phase control thyristor

1. A thyristor comprising:

a) a semiconductor slab, in which a thyristor structure is formed,

b) a cathode metallization formed on a cathode region on a cathode side surface of the semiconductor slab,

c) a gate metallization formed on a gate region on the cathode side surface of the semiconductor slab,

d) a plurality of N discrete emitter shorts, arranged at points P i in the cathode region, said points having point locations x i , with iϵ{1; . . . ; N},

e) the points P i being defined by a Delaunay triangulation comprising a plurality of triangles T j with jϵ{1; . . . ; M},

wherein

f) for a first subset of triangles T l with lϵS 1 ⊆{1; . . . ; M}, or S 1 ={1; . . . ; M},

g) with each triangle T l being characterized by a geometric quantity having values q T,l with lϵS 1 ⊆{1; . . . ; M}, said geometric quantity having a mean value μ, and

i) a coefficient of variation of the values q T,l with lϵS 1 is smaller than 0.1, and/or

ii) an absolute value of a skewedness of the geometric quantities q T,l with lϵS 1 is smaller than 5, and/or

iii) a Kurtosis of the geometric quantities q T,l with lϵS 1 is smaller than 20, and

h) for a second subset of triangles T m with mϵS 2 ⊂S 1 , for which the respective geometric quantities q T,m with mϵS 2 deviate from the mean value by more than 30%,

(1) a quotient of a standard deviation of the quantities q T,m with mϵS 2 and a mean squared value of the geometric quantity q T,l with lϵS 1 is less than 1, and/or

(2) a quotient of a number of triangles in the second subset and a number of triangles in the first subset is less than 1.0×10 −2 .

2. The thyristor according to claim 1 , wherein

h) the coefficient of variation of the values q T,l with lϵS 1 is larger than 0.0001, and/or

i) the absolute value of the skewedness of the geometric quantities q T,l with lϵS 1 is larger than 0.0001, and/or

j) the Kurtosis of the geometric quantities q T,l with lϵS 1 is larger than 3.0001, and/or

k) for the second subset of triangles T m with mϵS 2 ⊂S 1 , for which the respective geometric quantities q T,m with mϵS 2 deviate from the mean value by more than 30%,

(1) the quotient of a standard deviation of the quantities q T,m with m∈S 2 and a mean squared value of the geometric quantity q T,l with l∈S 1 is larger than 0.0001, and/or

(2) the quotient of a number of triangles in the second subset and a number of triangles in the first subset is larger than 10 −6 .

3. The thyristor according to claim 1 , wherein for all triangles in the first subset, the geometric quantity q T,l is defined as either

a) a length D l of the longest edge in each triangle T l with l∈S 1 ,

b) a smallest angle α min,l in each triangle T l with l∈S 1 ,

c) a largest angle in each triangle T l with l∈S 1 ,

d) a radius r min,l of a circle inscribed in each triangle T l with l∈S 1 ,

e) a radius r max,l of a circle circumscribed around each triangle T l with l∈S 1 , or

f) a quality index q l given by q ,l =r min,l /r max,l for each triangle T l with l∈S 1 .

4. A thyristor comprising:

a) a semiconductor slab in which a thyristor structure has been formed,

b) a cathode metallization formed on a cathode region on a cathode side surface of the semiconductor slab,

c) a gate metallization formed on a gate region on the cathode side surface of the semiconductor slab,

d) a plurality of N discrete emitter shorts, arranged at points P i in the cathode region, said points having point locations x i , with i∈{1; . . . ; N},

e) the points P i defining a Delaunay triangulation comprising a plurality of triangles T j with j∈{1; . . . ; M},

wherein

f) for a first subset of points P l with l∈S 1 ⊆{1; . . . ; N}, in particular S 1 ={1; . . . ; N},

g) with each point P l being characterized by a geometric quantity having values q P,l with l∈S 1 ⊆{1; . . . ; N}, said geometric quantity having a mean value μ, and

i) a coefficient of variation of the values q P,l with l∈S 1 is smaller than 0.1, and/or

ii) an absolute value of a skewedness of the geometric quantities q P,l with l∈S 1 is smaller than 5, and/or

iii) a Kurtosis of the geometric quantities q P,l with l∈S 1 is smaller than 20, and

h) for a second subset of points P m with m∈S 2 ⊆S 1 for which the respective geometric quantities q P,m with m∈S 2 deviate from the mean value by more than 30%,

(1) a quotient of a standard deviation of the quantities q P,m with m∈S 2 and a mean squared values of the geometric quantity q P,l with l∈S 1 ⊆{1; . . . ; N} is less than 1, and/or

(2) a quotient of a number of points in the second subset and a number of triangles in the first subset is less than 1.0×10 −2 .

5. The thyristor according to claim 4 , wherein

i) the coefficient of variation of the values q P,l with l∈S 1 is larger than 0.0001, and/or

ii) the absolute value of the skewedness of the geometric quantities q P,l with l∈S 1 is larger than 0.0001, and/or

iii) the Kurtosis of the geometric quantities q P,l with l∈S 1 is larger than 3.0001, and

h) for the second subset of points P m with m∈S 2 ⊂S 1 , for which the respective geometric quantities q P,m with m∈S 2 deviate from the mean value by more than 30%,

(1) the quotient of a standard deviation of the quantities q P,m with m∈S 2 and a mean squared value of the geometric quantity q P,l with l∈S 1 is larger than 0.0001, and/or

(2) the quotient of a number of points in the second subset and a number of triangles in the first subset is larger than 10 −6 .

6. The thyristor according to claim 4 , wherein for all points in the first subset, the geometric quantities q T,l are defined as either

a) a number N edges,l of edges connected to each point P l with l∈S 1 ,

b) a number N triangles,l of triangles sharing each point P l with l∈S 1 ,

c) a length l min,l of a shortest edge connected to each point P l with l∈S 1 ,

d) a length l max,l of a longest edge connected to each point P l with l∈S 1 , or

e) a Volume V l of Voronoi cell associated with each point P l with l∈S 1 .

7. The thyristor according to claim 1 , wherein a turn function difference TFD1 between an outer boundary of the cathode region and an outer envelope of the emitter shorts distribution, which is a smallest contour enclosing all emitter short locations in the cathode region, wherein TDF1 being defined as

TFD

⁢

⁢

1

=

∫



Θ

cathode

,

outer

-

Θ

env

,

outer



⁢

ds

2

⁢

π

⁢

∫

cathode

,

outer

⁢

ds

with □ cathode,outer being a turn function of the outer cathode region boundary and □ env,outer being a turn function of the outer envelope of the emitter shorts distribution

and/or a turn function difference between an inner envelope of the emitter shorts distribution and an outer boundary of the gate region is less than 0.15 and larger than 10 −4 .

8. The thyristor according to claim 1 , wherein the first subset comprises all points or all triangles located within a circle C with a diameter d C circumscribing the gate electrode, which diameter d C is smaller than a diameter d wafer of the slab or 0.75 d wafer , or within a minimal circle C min , which is a circle with a minimum diameter d C, min circumscribing the gate electrode.

9. The thyristor according to claim 8 , wherein the first subset comprises all points or all triangles located within a circle C′, said circle C′ being concentric to C or C min and having a diameter d C′ with d C′ >0.75 d C .

10. The thyristor according to claim 1 , wherein the number of points or the number of triangles in the first subset is larger than 250.

11. The thyristor according to claim 1 , wherein the number of points or of triangles in the first subset is larger than 0.8 N.

12. The thyristor according to claim 1 , wherein a coefficients of variation of the distance d closest between any given point on the boundary and the location of the emitter short closest to said point over the inner boundary and/or the outer boundary of the cathode region of less than 0.2.

13. The thyristor according to claim 1 , wherein the Delaunay triangulation is a restricted Delaunay triangulation on the cathode region.

14. The thyristor according to claim 1 , wherein for all triangles in the first subset, the geometric quantity q T,l is defined as either

a) a length D l of the longest edge in each triangle T l with l∈S 1 ,

b) a smallest angle α min,l in each triangle T l with l∈S 1 ,

c) a largest angle in each triangle T l with l∈S 1 ,

d) a radius r min,l of a circle inscribed in each triangle T l with l∈S 1 ,

e) a radius r max,l of a circle circumscribed around each triangle T l with l∈S 1 , or

f) a quality index q l given by q ,l =r min,l /r max,l for each triangle T l with l∈S 1 .

15. The thyristor according to claim 5 , wherein for all points in the first subset, the geometric quantities q T,l are defined as either

a) a number N edges,l Of edges connected to each point P l with l∈S 1 ,

b) a number N triangles,l Of triangles sharing each point P l with l∈S 1 ,

c) a length l min,l of a shortest edge connected to each point P l with l∈S 1 ,

d) a length l max,l of a longest edge connected to each point P l with l∈S 1 , or

e) a Volume V l of Voronoi cell associated with each point P l with l∈S 1 .

16. The thyristor according to claim 1 , wherein:

i) the coefficient of variation of the values q T,l with lϵS 1 is smaller than 0.05, and/or

ii) the absolute value of a skewedness of the geometric quantities q T,l with lϵS 1 is smaller than 1, and/or

iii) the Kurtosis of the geometric quantities q T,l with lϵS 1 is smaller than 10, and

h) for the second subset of triangles T m with mϵS 2 ⊂S 1 , for which the respective geometric quantities q T,m with mϵS 2 deviate from the mean value by more than 30%,

(1) the quotient of a standard deviation of the quantities q T,m with mϵS 2 and a mean squared value of the geometric quantity q T,l with lϵS 1 is less than 0.1, and/or

(2) the quotient of a number of triangles in the second subset and a number of triangles in the first subset is less than 0.5×10 −3 .

17. The thyristor according to claim 1 , wherein:

h) the coefficient of variation of the values q T,l with lϵS 1 is larger than 0.01, and/or

i) the absolute value of the skewedness of the geometric quantities q T,l with lϵS 1 is larger than 0.01, and/or

k) for the second subset of triangles T m with mϵS 2 ⊂S 1 , for which the respective geometric quantities q T,m with mϵS 2 deviate from the mean value by more than 30%,

(1) the quotient of a standard deviation of the quantities q T,m with m∈S 2 and a mean squared value of the geometric quantity q T,l with l∈S 1 is larger than 0.01, and/or

(2) the quotient of a number of triangles in the second subset and a number of triangles in the first subset is larger than 0.0001.

18. The thyristor according to claim 8 , wherein the first subset comprises all points or all triangles located within a circle C′, said circle C′ being concentric to C or C min and having a diameter d C ′ with d C′ >0.9 d C .

19. The thyristor according to claim 1 , wherein the number of points or the number of triangles in the first subset is larger than 1000.