Semiconductor Structure With Graded Body Contacts for EMI Suppression
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Solution Overview
Problem
Power semiconductor devices with reduced Miller capacitance for faster switching speed experience significant electromagnetic interference (EMI) due to large voltage and current oscillations.
Innovation Solution
A semiconductor device design featuring p-type body regions with varying doping concentrations for ohmic and non-ohmic contacts with the source metal layer, creating a gradually changing threshold voltage to reduce voltage and current oscillations, thereby minimizing EMI. The device includes p-type columns forming PN junctions with the n-type drift region and a source metal layer contact, with specific regions having higher or lower doping concentrations to control ohmic contact formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If Miller capacitance is reduced to improve switching speed, then switching loss is reduced, but voltage and current oscillations increase causing serious EMI
Solution Approach 1:
The patent applies local quality by differentiating the doping concentration of p-type body regions based on their spatial location. First regions (typically cell regions) have a first doping concentration that allows ohmic contact for low on-resistance, while second regions (typically termination regions) have a second doping concentration that prevents ohmic contact to suppress EMI. This local differentiation resolves the contradiction between fast switching and EMI suppression.
Solution Approach 2:
The semiconductor substrate is segmented into multiple regions with different p-type body region doping concentrations. The device structure is divided into first regions and second regions, each with tailored electrical characteristics. This segmentation allows different parts of the device to optimize for different functions: fast switching in cell regions and EMI suppression in termination regions.
2Loss of energy
If switching speed is increased to reduce switching loss, then power efficiency improves, but voltage and current oscillations become larger
Solution Approach 1:
By assigning different doping concentrations to different spatial regions, the patent creates local electrical characteristics that optimize for both fast switching and stability. First regions enable rapid charge discharge for low switching loss, while second regions provide controlled impedance to dampen oscillations and maintain voltage/current stability during transitions.
Solution Approach 2:
The patent changes the doping concentration parameter of p-type body regions based on location. First regions have higher doping concentration for low resistance and fast switching, while second regions have lower doping concentration to increase impedance and reduce oscillations. This parameter differentiation resolves the trade-off between switching speed and electrical stability.
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 design effectively reduces electromagnetic interference and improves the reverse recovery characteristic by stabilizing current and voltage transitions during switching, minimizing abrupt changes and oscillations.
Implementation Method 1
the source metal layer is in contact with the first p-type body region contact region to form an ohmic contact
Implementation Method 2
p-type columns forming PN junctions with the n-type drift region
Data Source
AI summary
Provided is a semiconductor device. The semiconductor device includes a semiconductor substrate, p-type body regions disposed in the semiconductor substrate, and p-type columns. The p-type body regions are in contact with a source metal layer. The p-type columns are disposed in the semiconductor substrate, each of the p-type columns is below a respective one of the p-type body regions. The semiconductor substrate includes at least one first region, and a region of the semiconductor substrate outside the at least one first region is a second region. A p-type body region of p-type body regions in the first region is provided with a first p-type body region contact region, and the source metal layer is in contact with the first p-type body region contact region to form an ohmic contact. Each of p-type body regions in the second region forms no ohmic contact with the source metal layer.