ZENER DIODES AND METHODS OF MANUFACTURE

1 . A semiconductor device, comprising:

a heavily-doped substrate of a first conductivity type;

a lightly-doped epitaxial layer of a second conductivity type disposed on the heavily-doped substrate, the second conductivity type being opposite the first conductivity type; and

a heavily-doped epitaxial layer of the second conductivity type disposed on the lightly-doped epitaxial layer, the heavily-doped epitaxial layer having a doping concentration that is greater than a doping concentration of the lightly-doped epitaxial layer,

at least a portion of the heavily-doped substrate being included in a first terminal of a Zener diode, and

at least a portion of the lightly-doped epitaxial layer and at least a portion of the heavily-doped epitaxial layer being included in a second terminal of the Zener diode,

the semiconductor device further comprising a termination trench that:

extends through the heavily-doped epitaxial layer;

extends through the lightly-doped epitaxial layer; and

extends into the heavily-doped substrate.

2 . The semiconductor device of claim 1 , further comprising at least one of a dielectric material or a polysilicon material disposed in the termination trench.

3 . The semiconductor device of claim 1 , wherein the termination trench is adjacent to and disposed, at least in part, around the at least a portion of the lightly-doped epitaxial layer and the at least a portion of the heavily-doped epitaxial layer.

4 . The semiconductor device of claim 1 , wherein the first conductivity type is n-type, the second conductivity type is p-type, the first terminal of the Zener diode is a cathode terminal, and the second terminal of the Zener diode is an anode terminal.

5 . The semiconductor device of claim 1 , wherein the first conductivity type is p-type, the second conductivity type is n-type, the first terminal of the Zener diode is an anode terminal, and the second terminal of the Zener diode is a cathode terminal.

6 . The semiconductor device of claim 1 , wherein the heavily-doped epitaxial layer has a thickness that is greater than a thickness of the lightly-doped epitaxial layer.

7 . The semiconductor device of claim 6 , wherein:

the thickness of the heavily-doped epitaxial layer is in a range between 3 micrometers (μm) and 30 μm; and

the thickness of the lightly-doped epitaxial layer is in a range between 0.5 μm and 10 μm.

8 . The semiconductor device of claim 1 , wherein:

the doping concentration of the lightly-doped epitaxial layer is in a range of 1×10 15 cm −3 to 1×10 19 cm −3 ; and

the doping concentration of the heavily-doped epitaxial layer is in a range of 1×10 18 cm −3 to 1×10 20 cm −3 ;

9 . The semiconductor device of claim 8 , wherein the termination trench extends into the heavily-doped substrate to a depth that is between 0.5 μm and 20 μm.

10 . A semiconductor device, comprising:

a heavily-doped substrate of a first conductivity type;

a lightly-doped epitaxial layer of a second conductivity type disposed on the heavily-doped substrate, the second conductivity type being opposite the first conductivity type; and

a heavily-doped epitaxial layer of the second conductivity type disposed on the lightly-doped epitaxial layer, the heavily-doped epitaxial layer having a doping concentration that is greater than a doping concentration of the lightly-doped epitaxial layer,

at least a portion of the heavily-doped substrate being included in a common first terminal of a first Zener diode and a second Zener diode, and

a first portion of the lightly-doped epitaxial layer and a first portion of the heavily-doped epitaxial layer being included in a second terminal of the first Zener diode,

a second portion of the lightly-doped epitaxial layer and a second portion of the heavily-doped epitaxial layer being included in a second terminal of the second Zener diode,

the semiconductor device further comprising a termination trench that:

extends through the heavily-doped epitaxial layer;

extends through the lightly-doped epitaxial layer; and

extends into the heavily-doped substrate,

a first portion of the termination trench electrically isolating the first portion of the lightly-doped epitaxial layer and the first portion of the heavily-doped epitaxial layer from the second portion of the lightly-doped epitaxial layer and the second portion of the heavily-doped epitaxial layer.

11 . The semiconductor device of claim 10 , further comprising a dielectric material disposed in the termination trench.

12 . The semiconductor device of claim 10 , wherein:

a second portion of the termination trench is adjacent to and disposed, at least in part, around the first portion of the lightly-doped epitaxial layer and the first portion of the heavily-doped epitaxial layer; and

a third portion of the termination trench is adjacent to and disposed, at least in part, around the second portion of the lightly-doped epitaxial layer and the second portion of the heavily-doped epitaxial layer

13 . The semiconductor device of claim 10 , wherein:

the first conductivity type is n-type;

the second conductivity type is p-type;

the common first terminal of the first Zener diode and the second Zener diode is a common cathode terminal;

the second terminal of the first Zener diode is a first anode terminal; and

the second terminal of the second Zener diode is a second anode terminal.

14 . The semiconductor device of claim 10 , wherein:

the first conductivity type is p-type;

the second conductivity type is n-type;

the common first terminal of the first Zener diode and the second Zener diode is a common anode terminal;

the second terminal of the first Zener diode is a first cathode terminal; and

the second terminal of the second Zener diode is a second cathode terminal.

15 . The semiconductor device of claim 10 , wherein the heavily-doped epitaxial layer has a thickness that is greater than a thickness of the lightly-doped epitaxial layer.

16 . The semiconductor device of claim 15 , wherein:

the thickness of the heavily-doped epitaxial layer is in a range between 5 micrometers (μm) and 20 μm; and

the thickness of the lightly-doped epitaxial layer is in a range between 0.5 μm and 10 μm.

17 . The semiconductor device of claim 10 , wherein:

the doping concentration of the lightly-doped epitaxial layer is in a range of 1×10 15 cm −3 to 1×10 19 cm −3 ; and

the doping concentration of the heavily-doped epitaxial layer is in a range of 1×10 19 cm 3 to 1×10 20 cm −3 ;

18 . The semiconductor device of claim 17 , wherein the termination trench extends into the heavily-doped substrate to a depth that is between 0.5 μm and 20 μm.

19 . A semiconductor device, comprising:

a heavily-doped substrate of a first conductivity type;

a lightly-doped epitaxial layer of a second conductivity type disposed on the heavily-doped substrate, the second conductivity type being opposite the first conductivity type; and

a heavily-doped epitaxial layer of the second conductivity type disposed on the lightly-doped epitaxial layer, the heavily-doped epitaxial layer having a thickness that is greater than a thickness of the lightly-doped epitaxial layer,

at least a portion of the heavily-doped substrate being included in a first terminal of a Zener diode, and

at least a portion of the lightly-doped epitaxial layer and at least a portion of the heavily-doped epitaxial layer being included in a second terminal of the Zener diode,

the semiconductor device further comprising a termination trench that:

extends through the heavily-doped epitaxial layer;

extends through the lightly-doped epitaxial layer; and

extends into the heavily-doped substrate.

20 . The semiconductor device of claim 19 , wherein the termination trench is adjacent to and disposed around the at least a portion of the lightly-doped epitaxial layer and the at least a portion of the heavily-doped epitaxial layer.