Merged PN Schottky Diode Embedded Wells
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
MPS diodes face challenges in achieving a balance between low forward voltage drop and low reverse leakage current, with existing designs not effectively increasing the Schottky active area to reduce resistance.
Innovation Solution
The solution involves embedding p-type wells beneath the surface of a substrate in an MPS diode, creating an embedded junction barrier grid that increases the Schottky active area, thereby reducing the forward voltage drop while maintaining low reverse leakage current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the Schottky junction region area is increased to reduce forward voltage drop, then the forward voltage drop decreases, but the reverse leakage current increases
Solution Approach 1:
The patent segments the Schottky contact area into two distinct regions: a first Schottky contact region over the n-type drift region and a second Schottky contact region over the p-type wells. This segmentation allows each region to serve different functions - the first region handles forward conduction while the second region, being smaller, limits reverse leakage current. The segmentation resolves the contradiction by enabling the total Schottky area to be effectively increased for low forward voltage drop while the distributed smaller regions maintain low reverse leakage.
Solution Approach 2:
The patent applies local quality by creating regions with different Schottky contact characteristics. The first Schottky contact region has different properties (larger area, direct contact with n-type drift region) optimized for forward conduction, while the second Schottky contact region has different properties (smaller area, contact with p-type wells) optimized for limiting reverse leakage. This local differentiation allows the device to simultaneously achieve low forward voltage drop and low reverse leakage current.
2Loss of energy
If the Schottky active area is increased to reduce resistance, then the forward voltage drop decreases, but the device complexity increases
Solution Approach 1:
The patent merges the functions of increasing Schottky area for low forward voltage drop with the function of maintaining low reverse leakage through a unified MPS structure. The p-type wells are embedded within the n-type drift region, and both regions have Schottky contacts, creating a merged structure that achieves both goals simultaneously without requiring separate components or complex external circuitry. This merging reduces overall device complexity while achieving the desired performance.
Solution Approach 2:
The patent implements nesting by placing p-type wells within the n-type drift region, creating a nested structure where the second conductivity type regions are embedded in the first conductivity type region. This nested configuration allows the Schottky active area to be increased through the embedded wells while maintaining a compact, integrated structure that does not significantly increase device complexity. The nested design enables efficient use of space and simplifies the overall device architecture.
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 approach effectively decreases the forward voltage drop and enhances current capability while maintaining excellent reverse blocking voltage and low leakage current, improving the overall performance of the MPS diode.
Implementation Method 1
Schottky barrier diode (SBD) and its off-shoot merged PN/Schottky diode or junction barrier Schottky (JBS) diode
Implementation Method 2
The junction grid pinches off current flow under reverse bias but not under forward bias
Data Source
AI summary
A merged PN/Schottky diode is provided having a substrate of a first conductivity type and a grid of doped wells of the second conductivity type embedded in the substrate. A Schottky barrier metal layer makes a Schottky barrier contact with the surface of the substrate above the grid. Selected embedded wells in the grid make a Schottky barrier contact to the Schottky barrier metal layer, while most embedded wells do not. The diode forward voltage drop is reduced for the same diode area with reverse blocking benefits similar to a conventional JBS structure.