Field Plate Layout for High-Voltage Breakdown and Low On-Resistance
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Solution Overview
Problem
Conventional high voltage devices face limitations in breakdown voltage and operation speed due to the length of the drift region, which increases conduction resistance and voltage differences across the device, restricting its application scope.
Innovation Solution
The integration of a field plate with a low temperature coefficient (TC) not higher than 4 ohm/°C into the high voltage device, which enhances breakdown voltage and reduces conduction resistance by distributing the electric field and accumulating carriers during ON operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the length of the drift region is prolonged to enhance breakdown voltage, then the breakdown voltage is improved, but the conduction resistance increases and operation speed decreases
Solution Approach 1:
The patent introduces a field plate structure that extends the drift region functionality into a new dimensional space above the drift region. By forming a field plate over the drift region with a dielectric layer, the electric field distribution is modified in the vertical dimension, enabling enhanced breakdown voltage without increasing the lateral drift region length, thus maintaining fast operation speed.
Solution Approach 2:
The field plate acts as an intermediary structure between the drain and the drift region. It introduces a new conductive element that mediates the electric field distribution, allowing the drift region to maintain its original length while achieving higher breakdown voltage through the field plate's field effect.
2Reliability
If the length of the drift region is prolonged to enhance breakdown voltage, then the breakdown voltage is improved, but the conduction resistance increases
Solution Approach 1:
The field plate structure utilizes the vertical dimension above the drift region to enhance electric field control. This dimensional extension allows the drift region to keep its original short length (reducing conduction resistance) while the field plate provides additional breakdown voltage enhancement through its field effect.
Solution Approach 2:
The patent changes the electrical parameters by introducing the field plate with specific doping concentrations and geometric dimensions. The field plate's doping concentration (1×10^16 to 1×10^18 atoms/cm³) and thickness (0.5 to 5 μm) are optimized to alter the electric field distribution, achieving high breakdown voltage without increasing conduction resistance.
3Reliability
If the drift region length is increased to withstand higher voltage, then the breakdown voltage is improved, but the voltage difference between drift region and drain increases excessively
Solution Approach 1:
The field plate serves as an intermediary that redistributes the voltage difference. Instead of having an excessive voltage drop across a long drift region, the field plate mediates the electric field, creating a more gradual voltage distribution and reducing the sharp voltage differences that would otherwise occur at the drift region-drain junction.
Solution Approach 2:
By adjusting the field plate's doping concentration and geometric parameters, the patent optimizes the voltage distribution across the device. The field plate's electrical parameters are tuned to achieve smooth voltage transitions, preventing excessive voltage differences while maintaining high withstand voltage capability.
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 proposed solution effectively enhances the breakdown voltage and reduces conduction resistance of the high voltage device, expanding its application scope while maintaining a low temperature coefficient for the field plate.
Implementation Method 1
a field plate 25, which is formed on the drift oxide region 23 and in contact with the drift oxide region 23, wherein the field plate 25 is electrically conductive
Data Source
AI summary
A high voltage device includes: a semiconductor layer, a well, a drift oxide region, a body region, a gate, a source, a drain, and a field plate. The well has a first conductivity type, and is formed in a semiconductor layer. The drift oxide region is formed on the semiconductor layer. The body region has a second conductivity type, and is formed in the semiconductor layer, wherein the body region and a drift region are connected in a channel direction. The gate is formed on the semiconductor layer. The source and the drain have the first conductivity type, and are formed in the semiconductor layer, wherein the source and the drain are in the body region and the well, respectively. The field plate is formed on and connected with the drift oxide region, wherein the field plate is electrically conductive and has a temperature coefficient (TC) not higher than 4 ohm/° C.