Snake Shaped Poly Gate for High Voltage Switching Devices
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
High voltage switching devices face issues with breakdown voltage due to high voltage drops across metal runs, leading to decreased reliability and increased costs in existing solutions, such as complex poly plate layers and extra drain pads.
Innovation Solution
A high voltage switching device design featuring a substrate with an epitaxial layer, source and drain regions, and a snake-shaped poly gate over the drift region, which absorbs the majority of the high voltage drop, eliminating the need for extra pads and simplifying the manufacturing process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a metal run is used to connect the drain pad and resistor divider, then the drain voltage can be sensed, but the high voltage drop across the metal run decreases the breakdown voltage and reliability
Solution Approach 1:
The patent extracts the sensing function from the metal run and relocates it to the poly layer. The poly layer is positioned to sense the voltage at the drain region directly, eliminating the need for a metal run to carry the sensing signal. This separation removes the harmful voltage drop effect from the sensing path while preserving the voltage sensing capability.
Solution Approach 2:
The patent introduces an intermediate poly structure that acts as a mediator between the drain region and the sensing circuit. This poly layer is positioned over the drift region and connected to the drain region, serving as an intermediary sensing element that does not suffer from the same voltage drop issues as metal runs would.
2Reliability
If two poly plate layers are made to isolate metal's effect, then the electrical field distribution is improved, but the process complexity increases
Solution Approach 1:
The patent extracts the field isolation function from complex multi-layer poly structures and implements it using a single poly layer positioned strategically over the drift region. This poly layer isolates the electrical field effects without requiring multiple poly plate layers, thereby simplifying the fabrication process while maintaining reliable electrical field distribution.
Solution Approach 2:
The patent applies local quality by positioning the poly layer specifically over the drift region where field isolation is needed, rather than using comprehensive multi-layer structures throughout the device. This localized approach provides the necessary electrical field isolation while minimizing process complexity.
3Ease of manufacture
If an extra drain pad is added outside the switching device, then the resistor divider can be connected, but the cost increases
Solution Approach 1:
The patent makes the existing drain pad multi-functional by using it both for current conduction and for voltage sensing. The poly layer is positioned to sense the voltage at the drain region, which is already accessible through the existing drain pad structure. This eliminates the need for an extra drain pad while maintaining both current and voltage functionality.
Solution Approach 2:
The patent merges the current conduction function and voltage sensing function into a single integrated structure. The drain pad serves dual purposes: conducting current through the device and providing the sensing point for the poly layer. This consolidation eliminates the need for separate sensing pads and reduces the overall component count.
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 design enhances the breakdown voltage and reliability of high voltage switching devices by distributing the high voltage across the snake-shaped poly gate, providing a low voltage sense signal for control circuits without additional pads, thus improving both performance and cost-effectiveness.
Implementation Method 1
a snake shaped poly formed on the field oxide over the drift region, the snake shaped poly having a first end and a second end, the first end being contacted with the drain region, and the second end being close to the gate but being separated from the gate
Data Source
AI summary
A high voltage switching device and associated method of manufacturing, the high voltage switching device having a substrate, an epitaxial layer, a source region, a drain region, a drift region, a gate oxide, a filed oxide, a gate and a snake shaped poly.