Space-Charge Control Electrodes for High-Voltage Semiconductor Devices
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Solution Overview
Problem
Current power semiconductor devices face challenges in achieving high breakdown voltage with minimal on-resistance due to non-uniform electric fields in the gate-drain spacing, leading to premature breakdown and limitations in kilovolt switching applications.
Innovation Solution
A semiconductor device with multiple space-charge control electrodes and a biasing network that supplies individual bias voltages to each electrode, selected based on terminal bias voltages and electrode location, to control the space charge distribution and electric field profile.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the gate-drain spacing distance is increased to increase breakdown voltage, then the breakdown voltage is improved, but the device complexity and design difficulty increase
Solution Approach 1:
The gate-drain spacing is divided into multiple regions by inserting several space-charge control electrodes between the gate and drain. Each electrode independently controls the space charge distribution in its local region, allowing the electric field to be uniformly distributed across the entire gate-drain spacing. This segmentation approach achieves high breakdown voltage without requiring excessive gate-drain spacing distance.
2Strength
If field plate structures are used to decrease peak electric field near the gate electrode, then the breakdown voltage is improved, but the inter-electrode capacitance increases and maximum operating frequency decreases
Solution Approach 1:
Space-charge control electrodes are introduced as intermediary elements between the gate and drain. These electrodes are biased at intermediate potentials (between gate and drain voltages) to smoothly transition the electric field distribution. This intermediary approach reduces peak electric field without creating the large voltage differences across extended field plates that cause high capacitance, thereby maintaining high operating frequency.
3Strength
If multiple field plates are used to achieve uniform electric field, then the breakdown voltage is improved, but the configuration complexity and manufacturing precision requirements increase
Solution Approach 1:
Each space-charge control electrode is positioned at a specific location between gate and drain and assigned a particular bias voltage tailored to its local position. The bias voltage for each electrode is individually optimized based on its distance from the gate and drain, creating locally optimized electric field control. This local quality approach achieves uniform overall electric field distribution without requiring precise control of field plate lengths and dielectric thickness variations across the entire structure.
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 enhances the breakdown voltage and operating frequency of semiconductor devices by achieving a more uniform electric field and reducing premature breakdown, thereby improving device performance in high-voltage applications.
Implementation Method 1
the electric field profile in the gate-drain spacing having a distance, LGD, shown in FIG. 1 exhibits a strong peak near the gate edge
Implementation Method 2
efficient control over the space charge distribution in the gate-drain spacing is extremely challenging
Data Source
AI summary
A circuit including a semiconductor device having a set of space-charge control electrodes is provided. The set of space-charge control electrodes is located between a first terminal, such as a gate or a cathode, and a second terminal, such as a drain or an anode, of the device. The circuit includes a biasing network, which supplies an individual bias voltage to each of the set of space-charge control electrodes. The bias voltage for each space-charge control electrode can be: selected based on the bias voltages of each of the terminals and a location of the space-charge control electrode relative to the terminals and/or configured to deplete a region of the channel under the corresponding space-charge control electrode at an operating voltage applied to the second terminal.