Low forward voltage drop transient voltage suppressor and method of fabricating
AssigneeVishay General Semiconductor LLC
InventorsLung-Ching Kao, Pu-Ju Kung, Yu-Ju Yu
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Abstract
A low forward voltage drop transient voltage suppressor utilizes a low-reverse-voltage-rated PN diode electrically connected in parallel to a high-reverse-voltage-rated Schottky rectifier in a single integrated circuit device. The transient voltage suppressor is ideally suited to fix the problem of high forward voltage drop of PN diodes and high leakage of low reverse breakdown of Schottky rectifiers. The low-reverse-voltage PN rectifier can be fabricated through methods such as 1) double layers of epi (with higher concentration layer epi in the bottom) or 2) punch through design of PN diode by base with compression.
Claims24
A low forward voltage drop transient voltage suppressor comprising:
- a low-reverse-voltage rated PN diode;
- and
- a high-reverse-voltage rated Schottky rectifier electrically connected in parallel to the PN diode in a single integrated circuit device;
- wherein the PN diode is configured to dominate reverse voltage performance such that forward conduction is through the Schottky rectifier under low current density and reverse breakdown is controlled by the PN diode;
- and
- wherein the PN diode has an enlarged guard ring that dominates reverse voltage performance due to electrical field at a junction area of the PN diode that is away from a die surface of the transient voltage suppressor.
A single chip low forward voltage drop transient voltage suppressor comprising:
- a PN diode having a PN junction;
- a Schottky rectifier electrically connected in parallel with the PN diode
- wherein the PN diode is adapted for dominating reverse voltage performance such that forward conduction is through the Schottky rectifier under low current density and reverse breakdown being controlled by the PN junction;
- and
- wherein the transient voltage suppressor is constructed with a first and a second layer of epitaxy (epi) having a high electrical resistance epi for Schottky barrier forming, but the suppressor's voltage rating is derived from a PN interface of the first layer epi.
A method of fabricating a low forward voltage drop transient voltage suppressor comprising the steps of:
- creating a low-reverse-voltage rated PN diode with an enlarged guard ring on a substrate;
- and
- creating a high-reverse-voltage rated Schottky rectifier connected electrically parallel to the PN diode on the substrate;
- wherein the PN diode is configured to dominate reverse voltage performance such that forward conduction is through the Schottky rectifier under low current density and reverse breakdown is controlled by the PN diode;
- and
- wherein the enlarged guard ring dominates reverse voltage performance due to electrical field at a junction area of the PN diode that is away from a die surface of the transient voltage suppressor.
A low forward voltage drop transient voltage suppressor comprising:
- a low-reverse-voltage rated PN diode;
- and
- a high-reverse-voltage rated Schottky rectifier electrically connected in parallel to the PN diode in a single integrated circuit device;
- wherein the PN diode is configured to dominate reverse voltage performance such that forward conduction is through the Schottky rectifier under low current density and reverse breakdown is controlled by the PN diode;
- and
- wherein the transient voltage suppressor is constructed with a punch through design of the PN diode by base width compression, wherein the Schottky rectifier has a longer base width than the PN diode.
A low forward voltage drop transient voltage suppressor comprising:
- a low-reverse-voltage rated PN diode;
- and
- a high-reverse-voltage rated Schottky rectifier electrically connected in parallel to the PN diode in a single integrated circuit device;
- wherein the PN diode is configured to dominate reverse voltage performance such that forward conduction is through the Schottky rectifier under low current density and reverse breakdown is controlled by the PN diode;
- and
- wherein the Schottky rectifier has a higher reverse voltage rating than the parallel connected PN diode so that a surface electrical field of the Schottky will be much lower than a critical field of the PN diode when the PN diode is in a breakdown state.
A method of fabricating a low forward voltage drop transient voltage suppressor comprising the steps of:
- creating a low-reverse-voltage rated PN diode on a substrate;
- and
- creating a high-reverse-voltage rated Schottky rectifier connected electrically parallel to the PN diode on the substrate;
- wherein the PN diode is configured to dominate reverse voltage performance such that forward conduction is through the Schottky rectifier under low current density and reverse breakdown is controlled by the PN diode;
- and
- wherein the transient voltage suppressor is constructed with a first and a second layer of epitaxy (epi) having a high electrical resistance epi for Schottky barrier forming, but the suppressor's voltage rating is derived from a PN interface of the first layer epi.
A method of fabricating a low forward voltage drop transient voltage suppressor comprising the steps of:
- creating a low-reverse-voltage rated PN diode on a substrate;
- and
- creating a high-reverse-voltage rated Schottky rectifier connected electrically parallel to the PN diode on the substrate;
- wherein the PN diode is configured to dominate reverse voltage performance such that forward conduction is through the Schottky rectifier under low current density and reverse breakdown is controlled by the PN diode;
- and
- wherein the transient voltage suppressor is created using a punch through design of the PN diode using base width compression for allowing the Schottky rectifier to have a longer base width than the PN diode's base width.
A method of fabricating a low forward voltage drop transient voltage suppressor comprising the steps of:
- creating a low-reverse-voltage rated PN diode on a substrate;
- and
- creating a high-reverse-voltage rated Schottky rectifier connected electrically parallel to the PN diode on the substrate;
- wherein the PN diode is configured to dominate reverse voltage performance such that forward conduction is through the Schottky rectifier under low current density and reverse breakdown is controlled by the PN diode;
- and
- wherein the transient voltage suppressor is constructed so that the suppressor has a forward conduction through the Schottky rectifier under low current density and a reverse breakdown is controlled by the PN diode only.
Dependencies are inferred from the claim text.