Semiconductor Field Plate Potential Fixing for On-Resistance Stability
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Solution Overview
Problem
Existing semiconductor devices with field plates experience on-resistance fluctuations and current loss due to charge accumulation and potential differences, which are difficult to mitigate effectively.
Innovation Solution
A semiconductor device with a field plate electrically connected to a drain electrode, fixing its potential and preventing charge accumulation, and having a larger size than the gate electrode to reduce on-resistance fluctuations and current loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the field plate has a floating potential, then the breakdown voltage increases, but charges are easily produced within Poly-Si constituting the field plate or the interface between the insulation film and Poly-Si, causing on-resistance fluctuations
Solution Approach 1:
The field plate is electrically connected to the drain electrode to fix its potential, eliminating the floating potential condition. This prevents charge accumulation in the field plate and at the insulation film interface, thereby reducing on-resistance fluctuations while maintaining high breakdown voltage through the controlled potential distribution
2Strength
If one and the other ends of the field plate are connected with the high potential portion and the low potential portion, then a gradual potential change is produced reducing electric field concentration, but a current of 1 μA or higher flows in the field plate based on the potential difference, increasing current loss
Solution Approach 1:
The field plate is connected to the drain electrode to maintain the same potential, eliminating potential difference across the field plate. This prevents current flow through the field plate (reducing current loss) while still providing electric field control benefits through the gate electrode's potential distribution
3Reliability
If the field plate is made larger than the gate electrode in the direction of current flow, then the reduction of on-resistance fluctuations is enhanced, but the device complexity increases
Solution Approach 1:
By connecting the field plate to the drain electrode to fix its potential, the invention achieves effective reduction of on-resistance fluctuations. The extended size of the field plate beyond the gate electrode provides broader coverage for potential stabilization, and this complexity is accepted as necessary to achieve the reliability improvement
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 solution effectively reduces on-resistance fluctuations and current loss by preventing charge accumulation and potential differences, improving the performance of semiconductor switching elements.
Implementation Method 1
a field plate arranged on the separation insulation film between the gate electrode and the first electrode and electrically connected with the first electrode to be fixed to a potential of the first electrode
Data Source
AI summary
A semiconductor device includes a lateral transistor having: a semiconductor substrate including a drift layer; a first impurity layer in the drift layer; a channel layer in the drift layer; a second impurity layer in the channel layer; a separation insulation film on the drift layer between the channel layer and the first impurity layer; a gate insulation film on a channel region between the second impurity layer and the drift layer connected with the separation insulation film; a gate electrode on the gate insulation film and the separation insulation film; a first electrode connected with the first impurity layer; a second electrode connected with the second impurity layer and the channel layer; and a field plate on the separation insulation film between the gate electrode and the first electrode and connected with the first electrode. The field plate is larger than the gate electrode in a current direction.