Semiconductor Layout With Selective Ohmic Contact for Lower EMI
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Solution Overview
Problem
Power semiconductor devices with reduced Miller capacitance for faster switching speed suffer from significant electromagnetic interference (EMI) due to large voltage and current oscillations.
Innovation Solution
A semiconductor device design featuring alternately arranged n-type and p-type collector regions, an n-type drift region, and p-type body regions with varying doping concentrations for ohmic and non-ohmic contacts with the emitter metal layer, which reduces voltage and current oscillations by creating a gradually changing threshold voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the switching speed is increased to reduce switching loss, then the switching speed is improved, but voltage and current oscillations increase leading to severe electromagnetic interference
Solution Approach 1:
The patent applies local quality by creating different regions within the semiconductor device: a first region with p-type body regions that form ohmic contacts with the emitter metal layer, and a second region where p-type body regions do not form ohmic contacts. This spatial differentiation allows different parts of the device to have different electrical characteristics, enabling controlled switching behavior that reduces oscillations while maintaining switching speed.
Solution Approach 2:
The patent changes the doping concentration parameter of p-type body regions to create varying electrical properties across different regions. By adjusting doping concentrations, the threshold voltage characteristics are modified to prevent abrupt changes during switching, thereby reducing voltage and current oscillations while maintaining fast switching performance.
2Reliability
If ohmic contact is formed in all p-type body regions, then electrical conductivity is improved, but threshold voltage changes become abrupt causing oscillations
Solution Approach 1:
The patent implements local quality by selectively forming ohmic contacts only in the first region where p-type body regions are present, while intentionally leaving the second region without ohmic contacts. This localized approach ensures good electrical conductivity where needed while preventing abrupt threshold voltage changes in other areas, thus stabilizing the overall device behavior during switching.
Solution Approach 2:
The patent segments the semiconductor device into distinct functional regions: a first region with ohmic-contacted p-type body regions for current conduction, and a second region without ohmic contacts for threshold voltage stabilization. This segmentation allows each region to perform its specific function optimally, resolving the contradiction between conductivity and 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 minimizes EMI and improves the reverse recovery characteristic of the semiconductor device by reducing abrupt changes in current and voltage during switching, thereby enhancing the device's performance.
Implementation Method 1
the emitter metal layer is in contact with the first p-type body region contact region and forms an ohmic contact with the first p-type body region contact region
Data Source
AI summary
Provided is a semiconductor device. The semiconductor device includes a semiconductor substrate and p-type body regions are disposed at a top of the semiconductor substrate. The p-type body regions are in contact with an emitter metal layer. 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. Each of p-type body regions in the at least one first region is provided with a first p-type body region contact region, and the emitter metal layer is in contact with the first p-type body region contact region and forms an ohmic contact with the first p-type body region contact region. Each of p-type body regions in the second region forms no ohmic contact with the emitter metal layer.