Super-Junction MOSFET Pillar Layout for Lower Switching Loss
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Solution Overview
Problem
Super-junction MOSFETs face energy loss during on/off operations due to parasitic capacitance, which limits their switching speed and frequency.
Innovation Solution
A semiconductor device design with specific doping concentrations and layer structures in the active, frame, and termination regions, including P and N pillars, and termination layers, to minimize energy loss by optimizing the doping profiles and layer thicknesses, and using a mask layer to adjust pillar distances and doping concentrations for reduced charge amounts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the internal pressure is increased to improve breakdown voltage, then the drift layer is thickened, but on-resistance is increased
Solution Approach 1:
The drift layer is segmented into multiple regions with different doping concentrations (first drift layer with higher concentration, second drift layer with lower concentration). This segmentation allows the device to achieve both high breakdown voltage (through the thicker overall drift layer) and low on-resistance (through the higher concentration region), resolving the contradiction between these two parameters.
2Speed
If parasitic capacitance is reduced to improve switching speed, then the gate oxide layer thickness is decreased, but breakdown voltage is reduced
Solution Approach 1:
Different regions of the device have different gate oxide layer thicknesses. The active region has a thinner gate oxide layer (50-150 nm) for low parasitic capacitance and high switching speed, while the termination region has a thicker gate oxide layer (150-300 nm) for high breakdown voltage. This local differentiation resolves the contradiction between switching speed and breakdown voltage.
3Loss of energy
If the doping concentration is increased to reduce on-resistance, then the breakdown voltage is reduced
Solution Approach 1:
The drift layer is divided into multiple segments with different doping concentrations. The first drift layer has a higher doping concentration (1×10^16 to 1×10^18 atoms/cm³) to reduce on-resistance, while the second drift layer has a lower doping concentration (1×10^15 to 1×10^17 atoms/cm³) to maintain breakdown voltage. This segmented approach allows both parameters to be optimized simultaneously.
Data Source
AI summary
A semiconductor device is provided. A semiconductor device includes: a first semiconductor layer having an N conductivity type; and a second semiconductor layer formed on the first semiconductor layer and including an active region, a frame region, and a termination region, wherein the active region may include a plurality of first P pillars and first N pillars formed between the plurality of first P pillars, the frame region includes a plurality of second P pillars and second N pillars formed between the plurality of second P pillars, the termination region may include a first surface termination layer having a P conductivity type and formed to extend in a first direction, a second surface termination layer having an N conductivity type and formed to extend in the first direction under the first surface termination layer, a first low-concentration termination layer having a P conductivity type and formed to extend in the first direction under the second surface termination layer, and a second low-concentration termination layer having an N conductivity type and formed in the first direction under the first low-concentration termination layer.