High-Voltage Device Structure
First Claim
1. A high-voltage device, comprising:
- a substrate a silicon mesa formed on the substrate, wherein the silicon mesa provides a drift region having a constant doping profile;
a recessed gate and source formed on the silicon mesa;
a trench adjacent each side of the silicon mesa; and
a metal-dielectric field plate structure formed in each trench;
wherein each metal-dielectric field plate structure comprises a dielectric and a metal field plate formed over the dielectric, and wherein a thickness of the dielectric increases linearly through a depth of the trench to provide a constant longitudinal electric field.
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Accused Products
Abstract
The present invention provides a vertical tapered dielectric high-voltage device (10) in which the device drift region is depicted by action of MOS field plates (30) formed in vertical trenches. The high-voltage device comprises: a substrate (32); a silicon mesa (20) formed on the substrate and having a stripe geometry, wherein the silicon mesa provides a drift region having a constant doping profile; a recessed gate (22) and source (SN) formed on the silicon mesa; a trench (26) adjacent each side of the silicon mesa; and a metal-dielectric field plate structure (12) formed in each trench; wherein each metal-dielectric field plate structure comprises a dielectric (28) and a metal field plate (30) formed over the dielectric, and wherein a thickness of the dielectric increases linearly through a depth of the trench to provide a constant longitudinal electric field.
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Citations
20 Claims
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1. A high-voltage device, comprising:
a substrate a silicon mesa formed on the substrate, wherein the silicon mesa provides a drift region having a constant doping profile;
a recessed gate and source formed on the silicon mesa;
a trench adjacent each side of the silicon mesa; and
a metal-dielectric field plate structure formed in each trench;
wherein each metal-dielectric field plate structure comprises a dielectric and a metal field plate formed over the dielectric, and wherein a thickness of the dielectric increases linearly through a depth of the trench to provide a constant longitudinal electric field.- View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A high-voltage device comprising:
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a substrate; a silicon stripe formed on the substrate; a silicon mesa formed in the silicon stripe, wherein the silicon mesa provides a drift region having a constant doping profile; a recessed gate and source (SN) formed on the silicon mesa; a trench adjacent each side of the silicon stripe; and a metal-dielectric field plate structure (formed in each trench along the silicon stripe; wherein each metal-dielectric field plate structure comprises a dielectric and a metal. field plate formed over the dielectric, and wherein a thickness of the dielectric increases linearly through a depth of the trench to provide a constant longitudinal electric field. - View Dependent Claims (13, 14, 15, 16, 17)
where Ex is longitudinal electric field, EO is permittivity of free space, is permittivity of the dielectric, q is magnitude of electronic charge, Nd is doping concentration within the silicon mesa, tsoi is thickness of the silicon stripe, and c is a constant related to gate oxide-field plate transition.
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14. The device of claim 12, wherein the device comprises an n-channel double diffused metal oxide semiconductor (DMOS) transistor.
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15. The device of claim 12, wherein the device comprises an insulated gate bipolar
transistor (IGBT). -
16. The device of claim 12, wherein the silicon stripe has a width of 3-5 pm, wherein the dielectric of metal-dielectric field plate structure has a maximum thickness of 5.5-6.5 pm, wherein the constant doping in the silicon mesa is 1.0-3.5×
- 1016 cm−
3.
- 1016 cm−
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17. The device of claim 12, wherein a 750 V device has a specific on-resistance in the range of 0.4-1.0 ohm mm2.
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18. A method for forming a high-voltage device, comprising:
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forming a silicon stripe on a substrate; forming a silicon mesa in the silicon stripe, wherein the silicon mesa provides a drift region having a constant doping profile; forming a recessed gate and source (SN) on the silicon mesa; forming a trench adjacent each side of the silicon stripe; and forming a metal-dielectric field plate structure in each trench along the silicon stripe; wherein each metal-dielectric field plate structure comprises a dielectric and a metal field plate formed over the dielectric, and wherein a thickness of the dielectric increases linearly through a depth of the trench to provide a constant longitudinal electric field. - View Dependent Claims (19, 20)
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Specification