Insulated Gate Semiconductor Device with Localized Curvature Control
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Solution Overview
Problem
Conventional insulated gate semiconductor devices with integrated operation and sense transistors face variations in depletion layer spreading due to differences in applied voltages, leading to instability in VDSS breakdown voltage, and this requires compromising on transistor arrangement areas to maintain reliability.
Innovation Solution
The design includes a first operation part and a second sense part with channel regions of opposite conductivity types, where the second part is smaller and surrounded by the first part, allowing for equal curvature corner portions and controlled depletion layer pinching to stabilize VDSS breakdown voltage, even with non-uniform depletion layer spreading.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the operation part and sense part are integrated into one chip with separated channel regions, then current detection and monitoring functions are achieved, but the VDSS breakdown voltage becomes unstable due to non-uniform depletion layer spreading
Solution Approach 1:
The patent applies local quality by giving different curvature characteristics to different regions of the channel region. Specifically, corner portions that face each other between the operation part and sense part are designed with equal curvatures to ensure uniform depletion layer spreading in critical areas, while other portions may have different curvatures. This localized curvature control stabilizes the VDSS breakdown voltage while maintaining the integrated structure's current detection functionality.
2Reliability
If the curvatures of corner portions in channel regions are set equal to stabilize VDSS breakdown voltage, then reliability is improved, but the arrangement area for transistors is reduced
Solution Approach 1:
The patent implements local quality by selectively equalizing curvatures only at specific corner portions that face each other between the operation part and sense part. These are the critical locations where depletion layer interaction occurs. Other corner portions and regions are not constrained to have equal curvatures, thereby maximizing the transistor arrangement area while still achieving VDSS breakdown voltage stability through localized curvature control.
3Productivity
If the operation part and sense part are disposed close to each other to maximize chip area utilization, then productivity is improved, but the depletion layers pinch off and influence the breakdown voltage
Solution Approach 1:
The patent applies local quality by controlling the curvature of corner portions at the interfaces between the operation part and sense part. By setting these specific corner curvatures to be equal, the patent ensures uniform depletion layer spreading even when the parts are disposed close together. This allows maximum chip area utilization while preventing unwanted depletion layer pinching off that would affect breakdown voltage.
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
This configuration stabilizes VDSS breakdown voltage characteristics across the chip by ensuring uniform depletion layer spreading at the chip's periphery, improving reliability without reducing the number of transistor arrangement areas.
Implementation Method 1
curvatures of depletion layers spreading outward from the respective channel regions 33 and 34 in application of a reverse voltage are set approximately equal
Data Source
AI summary
An insulated gate semiconductor device includes a one conductivity type semiconductor layer, a first operation part in a surface of the semiconductor layer and a second operation part in the surface of the semiconductor layer that is smaller in area than the first operation part. A first channel region and a first transistor of an opposite conductivity type are provided in the first operation part and a second channel region and a second transistor of the opposite conductivity type are provided in the second operation part. The first operation part is disposed around the second operation part. Accordingly, design rules for four corner portions can be made uniform and depletion layer spreading in corner portions at a peripheral edge of a channel region of an operation part in application of a reverse voltage is also made approximately uniform. Thus, stable VDSS breakdown voltage characteristics can be obtained.