Hybrid Substrate Power Semiconductor Structure for Lower Leakage
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Solution Overview
Problem
Conventional semiconductor power devices face challenges in improving high voltage performances, reducing off-state leakage current, and minimizing parasitic capacitance due to localized electric fields and substrate-related issues, which existing solutions have not adequately addressed.
Innovation Solution
A semiconductor power device structure is designed with a hybrid substrate layer comprising conductive and insulating substrate portions, replacing the conventional homo-conductive substrate, and incorporating a dual-level or multi-level back field plate to optimize electric field distribution and reduce parasitic capacitance, while enhancing thermal conductivity and reducing leakage currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional homo-conductive substrate is used with an integral back field plate, then the device structure is simple and easy to manufacture, but the localized electric field between the drain and substrate leads to poor high voltage performance and increased off-state leakage current
Solution Approach 1:
The substrate is segmented into a conductive substrate portion and an insulating substrate portion, with the conductive portion positioned beneath the source electrode and control region, and the insulating portion beneath the drain electrode. This segmentation eliminates the localized electric field between the drain and substrate, reducing off-state leakage current and improving high voltage performance while maintaining manageable device complexity through systematic regional differentiation.
Solution Approach 2:
Different regions of the substrate are assigned different electrical properties: the conductive substrate portion provides electrical connection and field modulation under the source and control regions, while the insulating substrate portion provides electrical isolation under the drain electrode. This local quality differentiation optimizes each region's function to simultaneously improve high voltage performance and control complexity.
2Reliability
If the substrate beneath the drain is removed and replaced with insulating material, then off-state leakage current is reduced, but the electric field optimization in the channel region is lost leading to uncontrolled dynamic resistance
Solution Approach 1:
The substrate is divided into conductive and insulating portions positioned at different locations. The conductive substrate portion remains beneath the source electrode and control region to maintain electric field optimization and dynamic resistance control, while the insulating substrate portion is placed beneath the drain electrode to reduce off-state leakage current. This spatial segmentation allows both requirements to be satisfied simultaneously.
Solution Approach 2:
The conductive substrate portion provides localized electric field modulation for optimal channel performance and controlled dynamic resistance, while the insulating substrate portion provides localized electrical isolation to minimize leakage current. Each region's specific electrical property is optimized for its functional requirements.
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 new structure significantly improves dynamic resistance characteristics, enhances high voltage performances, and reduces parasitic capacitance, leading to smaller switching losses and higher operation efficiency under high frequency.
Implementation Method 1
the intensity of a vertical electric field beneath the drain electrode can be significantly reduced in an off state under a high voltage
Implementation Method 2
the above replacement decreases capacitive coupling between the drain electrode and the conductive substrate, such that parasitic capacitance between a source grounding structure and a gate grounding structure is reduced
Implementation Method 3
a conductive equipotential body extending from a source or a gate is provided for modulating an electric field in a depletion region, so as to improve distribution of the electric field
Data Source
AI summary
A semiconductor power device and a method for manufacturing the same. The semiconductor power device comprises the back electrode, the substrate layer, the insulating buffer layer, the channel layer, the barrier layer, the dielectric layer, and the passivation layer, which are stacked sequentially from bottom to top. The substrate layer comprises a conductive substrate portion and an insulating substrate portion. The insulating buffer layer comprises a control region located above the conductive substrate portion, a high-voltage insulation region located beneath a drain electrode and above the insulating substrate portion, and a drift region between the control region and the high-voltage insulation region. The semiconductor power device has improved dynamic resistance characteristics, improved high voltage performances, and reduced parasitic capacitance.