LDMOS Integrated Schottky Diode for Low Forward Voltage
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing Schottky diodes do not efficiently integrate with MOSFET devices to achieve ultra-low forward voltage drop and effective blocking performance under reverse bias conditions, limiting their application in high-speed power switching and rectification.
Innovation Solution
A semiconductor device integrating a laterally diffused metal-oxide-semiconductor (LDMOS) transistor with a monolithically integrated Schottky diode, featuring a Schottky contact that clamps the internal body diode to minimize minority carrier injection and reverse recovery, utilizing a lateral gated Schottky diode design with specific doping profiles and structures to achieve low forward voltage drop and high breakdown voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a Schottky diode is designed with high doping concentration to reduce forward voltage drop, then forward conduction performance is improved, but blocking performance under reverse bias deteriorates due to high electric field effects
Solution Approach 1:
The patent introduces a lightly-doped drift region as an intermediary layer between the heavily-doped contact region and the Schottky interface. This drift region acts as a mediator that reduces the electric field strength at the Schottky interface under reverse bias, allowing high doping concentrations in the contact region to achieve low forward voltage drop while maintaining reliable blocking performance through the field-reducing effect of the drift region.
2Reliability
If a Schottky diode uses conventional vertical structure to achieve blocking voltage, then reverse bias performance is improved, but integration with MOSFET devices and area efficiency deteriorates
Solution Approach 1:
The patent transitions from a conventional vertical Schottky diode structure to a lateral Schottky diode structure where the Schottky interface is formed at the surface and current flows laterally through the drift region. This dimensional change enables monolithic integration with MOSFET devices on the same semiconductor substrate, reducing device complexity and improving area efficiency while maintaining blocking voltage performance through the carefully engineered drift region.
3Productivity
If a Schottky diode is integrated with MOSFET to enable synchronous rectification, then rectification efficiency is improved, but manufacturing process complexity increases
Solution Approach 1:
The patent designs a universal lateral Schottky diode structure that can be monolithically integrated with MOSFET devices using compatible semiconductor fabrication processes. The same drift region and doping techniques used in MOSFET manufacturing are leveraged to create the Schottky diode, enabling both devices to be manufactured together on the same substrate. This multi-functionality approach improves rectification efficiency through synchronous rectification while avoiding excessive increases in manufacturing process complexity.
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
The integrated LDMOS and Schottky diode structure achieves ultra-low forward voltage drop and enhanced blocking capabilities, outperforming prior art in terms of forward conduction and reverse recovery, with improved reliability and avalanche ruggedness.
Implementation Method 1
an anode contact forming a Schottky barrier with the at least one doped region
Data Source
AI summary
A semiconductor device includes a substrate having a first conductivity type and a semiconductor layer formed over the substrate and having lower and upper surfaces. A laterally diffused metal-oxide-semiconductor (LDMOS) transistor device is formed over the substrate and includes a source region of the first conductivity type and a drain extension region of the first conductivity type formed in the semiconductor layer proximate the upper surface of the semiconductor layer, and a drain contact electrically connecting the drain extension region to the substrate. A Schottky diode is formed over the substrate and includes at least one doped region of the first conductivity type formed in the semiconductor layer proximate to the upper surface, an anode contact forming a Schottky barrier with the at least one doped region, and a cathode contact laterally spaced from the anode contact and electrically connecting at least one doped region to the substrate.