Trench Field Plate MOSFET Air-Gap Structure for Lower On-Resistance
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Solution Overview
Problem
Existing power MOSFET devices face high on-resistance (Ron) values, contributing to significant power loss, which is not effectively addressed by current dielectric materials.
Innovation Solution
Incorporating an air gap in the field plate region of the MOSFET device, replacing silicon dioxide with air (k=1) to reduce the effective dielectric constant, thereby lowering on-state resistance (Rsil) and gate capacitance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If silicon dioxide dielectric material is used in the field plate region, then the device structure is simple and easy to manufacture, but the on-state resistance (Rsil) is high contributing to power loss
Solution Approach 1:
The patent changes the dielectric constant parameter by replacing silicon dioxide (k=3.9) with air gaps (k=1) in the field plate region. This parameter change directly reduces the on-state resistance Rsil and power loss, while the air gaps are formed through standard semiconductor fabrication processes such as sacrificial layer removal, maintaining manufacturing feasibility
Solution Approach 2:
The patent creates a composite dielectric structure combining air gaps with remaining dielectric material in the field plate region. This composite approach achieves lower effective dielectric constant and reduced power loss while maintaining structural integrity and electrical performance through the combination of different materials with complementary properties
2Loss of energy
If air gap is introduced to reduce dielectric constant and on-state resistance, then power loss is reduced, but the device structure becomes more complex
Solution Approach 1:
The patent introduces air gaps as porous structures in the field plate region, creating a porous dielectric configuration. This approach reduces the effective dielectric constant and on-state resistance while the air gaps are integrated into the existing device architecture through fabrication processes, avoiding excessive structural complexity
Solution Approach 2:
The patent segments the continuous dielectric material in the field plate region by introducing discrete air gaps. This segmentation creates multiple isolated air regions that collectively reduce the effective dielectric constant, achieving power loss reduction while maintaining a manageable structural complexity through standardized gap placement and sizing
3Use of energy by moving object
If silicon dioxide is used as dielectric material, then the manufacturing process is straightforward, but gate capacitance is high
Solution Approach 1:
The patent changes the dielectric constant parameter in the field plate region by introducing air gaps (k=1) instead of silicon dioxide (k=3.9). This parameter reduction directly decreases gate capacitance and improves energy efficiency, while the air gaps are formed through modifications to existing fabrication processes, maintaining manufacturing simplicity
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 air gap significantly reduces on-state resistance, overcoming the silicon limit and enhancing power MOSFET performance by minimizing power loss.
Implementation Method 1
replacing silicon dioxide with air (k=1) to reduce the effective dielectric constant, thereby lowering on-state resistance (Rsil) and gate capacitance
Data Source
AI summary
A power MOSFET device including at least one air gap between a buried polysilicon source and a sidewall of a recessed substrate. The device includes a plurality of insulating layers on the substrate and delimiting the air gap.