Low Forward Voltage Drop Transient Voltage Suppressor
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Solution Overview
Problem
Schottky rectifiers suffer from high reverse leakage at rated reverse voltage due to strong surface electrical fields, leading to a trade-off between forward conduction loss and reverse power loss, making them costly and inefficient for applications like hard disk control circuits.
Innovation Solution
A low forward voltage drop transient voltage suppressor is created by electrically connecting a low reverse voltage rated PN diode in parallel with a high reverse voltage rated Schottky rectifier in a single integrated circuit, utilizing a P-I-N Schottky rectifier with a PN diffusion profile for voltage control and surge protection, and constructing the device on a silicone substrate with epitaxy layers and implantation doping to reduce surface electrical fields.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If Schottky rectifiers are used to achieve low forward voltage drop, then forward conduction loss is reduced, but reverse leakage at rated reverse voltage increases significantly
Solution Approach 1:
The device is segmented into two distinct functional regions: a first region with a Schottky junction optimized for low forward voltage drop and a second region with a PN junction optimized for low reverse leakage. This segmentation allows each region to independently address one aspect of the contradiction without compromising the other.
Solution Approach 2:
Different local structures are implemented in different regions of the device. The Schottky region uses a metal-semiconductor contact with specific barrier properties for low forward voltage, while the PN region uses doped semiconductor layers with specific doping profiles for low reverse leakage. Each local structure is optimized for its specific function.
2Object-generated harmful factors
If PN structure diodes are used to achieve lower reverse leakage, then reverse power loss is reduced, but forward voltage drop increases due to build-in potential
Solution Approach 1:
The device is segmented into two distinct functional regions: a first region with a Schottky junction optimized for low forward voltage drop and a second region with a PN junction optimized for low reverse leakage. This segmentation allows each region to independently address one aspect of the contradiction without compromising the other.
Solution Approach 2:
Different local structures are implemented in different regions of the device. The Schottky region uses a metal-semiconductor contact with specific barrier properties for low forward voltage, while the PN region uses doped semiconductor layers with specific doping profiles for low reverse leakage. Each local structure is optimized for its specific function.
3Reliability
If separate Schottky rectifier and TVS devices are used for polarity protection and reverse surge protection, then protection functionality is achieved, but construction cost increases
Solution Approach 1:
The patent merges the functionality of a Schottky rectifier (for polarity protection) and a transient voltage suppressor (for reverse surge protection) into a single integrated device. The Schottky region provides polarity protection while the PN region provides reverse surge protection, eliminating the need for separate components and reducing construction cost.
Solution Approach 2:
The single device performs multiple protective functions: polarity protection through the Schottky region, reverse surge protection through the PN region, and general voltage suppression. This multi-functionality replaces what previously required separate dedicated components for each function.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution reduces reverse leakage and forward voltage drop, enabling efficient and economical protection against voltage surges in control circuits while maintaining high current ratings, as demonstrated by passing high temperature reverse bias testing without failure.
Implementation Method 1
Schottky rectifiers generally have a special barrier metal contact within the device to provide a low forward voltage drop
Implementation Method 2
PN structure diodes normally have lower reverse leakage performance than Schottky's. It is therefore unavoidable for the disadvantage of high forward voltage drop even under low current density due to the nature of build-in potential in the PN junction
Implementation Method 3
because the character of metal barrier and barrier lowering under high surface electrical field, Schottky rectifiers have long been denounced for their high reverse leakage at rated reverse voltage as being serious barrier lowering devices having strong surface electrical fields
Data Source
AI summary
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.