Structure and method for transient voltage suppression devices with a two-region base
View Patent ↗A transient voltage suppression (TVS) device and a method of forming the device are provided. The TVS device includes a first layer of wide band-gap semiconductor material formed of a first conductivity type material, a second layer of wide band-gap semiconductor material formed of a second conductivity type material over at least a portion of the first layer, the second layer including a first concentration of dopant. The TVS device further including a third layer of wide band-gap semiconductor material formed of the second conductivity type material over at least a portion of the second layer, the third layer including a second concentration of dopant, the second concentration of dopant being different than the first concentration of dopant. The TVS device further including a fourth layer of wide band-gap semiconductor material formed of the first conductivity type material over at least a portion of the third layer.
1. A transient voltage suppression (TVS) device comprising:
a first layer of wide band-gap semiconductor material formed of a first conductivity type material;
a second layer of wide band-gap semiconductor material formed of a second conductivity type material over at least a portion of the first layer, the second layer comprising a first thickness and a first concentration of dopant;
a third layer of wide band-gap semiconductor material formed of the second conductivity type material over at least a portion of the second layer, the third layer comprising a second thickness and a second concentration of dopant, the second thickness being larger than the first thickness, the second concentration of dopant being less than the first concentration of dopant; and
a fourth layer of wide band-gap semiconductor material formed of the first conductivity type material over at least a portion of the third layer, wherein a concentration of dopant in the second layer and the third layer is determined using:
N thirdlayer* t thirdlayer ≦ 10* N secondlayer* t secondlayer, where
Nthirdlayer represents a concentration of dopant in the third layer, wherein a concentration of dopant in the third layer is, 1×10 15 cm −3 <Nthirdlayer ≦ 2×10 17 cm −3 ,
tthirdlayer represents a thickness of the third layer,
Nsecondlayer represents a concentration of dopant in the second layer, and
tsecondlayer represents a thickness of the second layer, wherein a thickness of the second layer is, tsecondlayer>2 um.
2. The device of claim 1 , further comprising a first electrical contact surface on a side of the first layer opposite the second layer.
3. The device of claim 2 , further comprising a second electrical contact surface on a side of the fourth layer opposite the third layer.
4. The device of claim 1 , wherein a concentration of dopant in the second layer is, Nsecondlayer ≦ 1×10 18 cm −3 .
5. The device of claim 1 , wherein a thickness of the third layer is, tthirdlayer ≧ 0.5 um.
6. The device of claim 1 , wherein said TVS device operates using punch-through physics.
7. The device of claim 6 , wherein said TVS device is configured to exhibit punch-through characteristics between approximately 5.0 volts and approximately 75.0 volts.
8. The device of claim 6 , wherein said TVS device is configured to exhibit punch-through characteristics between approximately 75.0 volts and approximately 200.0 volts.
9. The device of claim 6 , wherein said TVS device is configured to exhibit punch-through characteristics at voltages greater than approximately 200 volts.
10. A transient voltage suppression (TVS) assembly for protecting electrical equipment from transient electrical energy configured to divert electrical energy from the electrical equipment, said TVS assembly comprising:
a plurality of TVS devices coupled together in at least electrical parallel, said plurality of TVS devices each comprising:
a first layer formed of a wide band-gap semiconductor material of a first conductivity type;
a second layer formed of the wide band-gap semiconductor material of a second conductivity type, the second layer comprising a first thickness and a first concentration of dopant;
a third layer of wide band-gap semiconductor material formed of the second conductivity type material over at least a portion of the second layer, the third layer comprising a second thickness and a second concentration of dopant, the second thickness being larger than the first thickness, the second concentration of dopant being less than the first concentration of dopant; and
a fourth layer of wide band-gap semiconductor material formed of the first conductivity type material over at least a portion of the third layer, wherein a concentration of dopant in the second layer and the third layer is determined using:
N thirdlayer* t thirdlayer ≦ 10 *N secondlayer* t secondlayer, where
Nthirdlayer represents a concentration of dopant in the third layer, wherein a concentration of dopant in the third layer is, 1×10 15 cm −3 <Nthirdlayer ≦ 2×10 17 cm 3 ,
tthirdlayer represents a thickness of the third layer,
Nsecondlayer represents a concentration of dopant in the second layer, and
tsecondlayer represents a thickness of the second layer, wherein a thickness of the second layer is, tsecondlayer>2 um.
11. The assembly of claim 10 , wherein said plurality of TVS devices are formed on a first die and packaged into a single integrated circuit package.
12. The assembly of claim 10 , wherein said plurality of TVS devices are formed monolithically on a single die.