Schottky Body Diode Structure for Lower-Loss Semiconductor Switching
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Solution Overview
Problem
In semiconductor devices, particularly transistors, the forward voltage of the body diode is high, leading to increased power loss and reduced switching speed due to the p-n junction-based body diode, which also results in longer recovery times.
Innovation Solution
The semiconductor device employs a Schottky barrier formed at the interface between the conductive portions and semiconductor regions, with varying work functions for the conductive regions to reduce the forward voltage of the body diode, utilizing a structure with a first conductive region in Schottky junction with a first semiconductor region and a second conductive region in Schottky junction with a second semiconductor region, where the work function of the first conductive region is smaller than the second when the first conductivity-type is n-type, and vice versa.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a p-n junction-based body diode is used in a semiconductor device, then the device structure is simple and easy to manufacture, but the forward voltage is high leading to increased power loss and longer recovery times
Solution Approach 1:
The patent changes the fundamental parameter of the body diode structure from a p-n junction to a Schottky junction. This parameter change reduces the forward voltage of the body diode, thereby reducing power loss during conduction. The Schottky junction achieves this by forming a metal-semiconductor contact instead of a p-n junction, which creates a lower potential barrier and reduces the voltage drop across the diode during forward conduction.
Solution Approach 2:
The patent employs composite material structure by combining metal layers with different work functions with semiconductor regions. The second conductive portion includes a first conductive region and a second conductive region with different work functions, forming a Schottky junction with the semiconductor portion. This composite structure of different materials (metals with varying work functions and semiconductor) enables the body diode to achieve lower forward voltage while maintaining structural integrity.
2Productivity
If a p-n junction-based body diode is used, then the manufacturing process is straightforward, but the recovery time is prolonged reducing switching speed
Solution Approach 1:
The patent changes the junction type parameter from p-n junction to Schottky junction, which fundamentally alters the carrier recombination mechanism. The Schottky junction exhibits faster recovery characteristics because it primarily relies on minority carrier drift rather than diffusion and recombination, significantly reducing the recovery time and enhancing switching speed for power electronic applications.
3Reliability
If conductive regions with varying work functions are used to reduce forward voltage, then power loss is minimized and recovery speed is enhanced, but the device structure becomes more complex
Solution Approach 1:
The patent applies local quality by creating different conductive regions with specific work function characteristics at different locations within the second conductive portion. The first conductive region and second conductive region are positioned to contact different semiconductor regions (first and second semiconductor regions respectively), with each region optimized for its specific function. This local differentiation of material properties enables the Schottky junction to achieve reduced forward voltage while maintaining overall device functionality.
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 configuration reduces the forward voltage of the body diode, minimizing power loss during diode conduction, enhancing recovery speed, and allowing for a more efficient and faster switching operation by eliminating the need for a p-n junction, thus improving overall device performance.
Implementation Method 1
the second conductive portion includes a first conductive region in Schottky junction with the first semiconductor region, and a second conductive region in Schottky junction with the second semiconductor region
Implementation Method 2
When the first conductivity-type is an n-type, a work function of the first conductive region is smaller than a work function of the second conductive region. When the first conductivity-type is a p-type, the work function of the first conductive region is larger than a work function of the second conductive region.
Data Source
AI summary
A semiconductor device includes first to third conductive portions, a first insulating portion, and a semiconductor portion. The semiconductor portion includes a first semiconductor region provided between the first conductive portion and the second conductive portion, and a second semiconductor region provided between the second conductive portion and the first insulating region. The second conductive portion includes a first conductive region in Schottky junction with the first semiconductor region, and a second conductive region in Schottky junction with the second semiconductor region. When the first conductivity-type is an n-type, a work function of the first conductive region is smaller than a work function of the second conductive region. When the first conductivity-type is a p-type, the work function of the first conductive region is larger than the work function of the second conductive region.