Optical Current Sensing in Bipolar Power Semiconductors
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Solution Overview
Problem
The development of new power semiconductor devices faces challenges in optimizing chip area consumption by sensing elements while maintaining reliability, particularly in integrating current and temperature sensing functions effectively.
Innovation Solution
A power semiconductor device incorporating a bipolar power semiconductor element with a current sensing element featuring a pn or pin junction, an optical window for electromagnetic radiation, and a measurement system to determine on-current by forcing voltage between pins and measuring current through them, allowing for combined temperature and current sensing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If sensing elements are integrated into the power semiconductor device, then measurement precision and device reliability are improved, but chip area consumption increases
Solution Approach 1:
The patent combines the current sensing function with the bipolar power semiconductor element itself. The bipolar element's base region serves dual purposes: as part of the power switching structure and as the sensing element for detecting on-current. This merging eliminates the need for separate sensing elements, thereby improving measurement precision while avoiding additional chip area consumption.
Solution Approach 2:
The bipolar power semiconductor element is designed to perform multiple functions simultaneously: power switching and current sensing. The base region of the bipolar element acts as both the active region for power conduction and the sensing region for detecting on-current through electromagnetic radiation. This multi-functionality resolves the contradiction by making the sensing element serve the dual purpose of power operation and measurement.
2Ease of manufacture
If chip area is reduced by shrinking device geometries, then manufacturing cost is reduced, but integration of sensing functions becomes more difficult
Solution Approach 1:
The sensing function is merged into the existing bipolar power element structure during the same manufacturing process. The base region is designed to serve both power conduction and sensing purposes, requiring no additional fabrication steps or separate integration processes. This approach reduces manufacturing complexity while maintaining cost benefits from smaller geometries.
Solution Approach 2:
The bipolar element is designed as a universal structure that performs both power switching and current sensing functions. This multi-functionality is achieved through the inherent properties of the bipolar transistor structure, where the base region naturally emits electromagnetic radiation proportional to the collector current. This eliminates the need for separate sensing element integration, simplifying the manufacturing process while reducing chip area.
3Measurement precision
If sensing element area is increased, then measurement precision is improved, but device reliability requirements become harder to meet
Solution Approach 1:
The sensing function is merged into the bipolar element's base region, which is already an essential part of the power switching structure. This merging ensures that the sensing element benefits from the same reliability design considerations as the power element, including proper doping, geometry, and material selection. The sensing function does not compromise reliability because it uses the existing robust bipolar structure.
Solution Approach 2:
The bipolar element serves as both the power device and the sensing element, ensuring that reliability requirements are met for both functions simultaneously. The base region's dual role means that reliability considerations for power conduction automatically apply to the sensing function, maintaining device reliability while achieving adequate measurement precision through the inherent electromagnetic radiation properties of the bipolar structure.
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 solution reduces chip area consumption by integrating sensing functions and improves reliability by enabling efficient measurement of on-current and temperature, addressing the trade-off between sensing element area and device reliability.
Implementation Method 1
an optical window (114) configured to allow electromagnetic radiation caused by an on-current of the bipolar power semiconductor element to pass to the current sensing element
Data Source
AI summary
A power semiconductor device is proposed. The power semiconductor device includes a semiconductor body and a wiring area over a first surface of the semiconductor body. The power semiconductor device further includes a bipolar power semiconductor element including a first load electrode in the wiring area, an active area in the semiconductor body, and a second load electrode at a second surface of the semiconductor body. The power semiconductor device further includes a current sensing element including a pn or pin junction. The power semiconductor device further includes an optical window configured to allow electromagnetic radiation caused by an on-current of the bipolar power semiconductor element to pass to the current sensing element.