Semiconductor Switch Temperature Sensor Shielding
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Solution Overview
Problem
Power semiconductor switches with integrated temperature sensors face significant capacitive coupling issues due to parasitic capacitances between wiring layers and contact layers, leading to distortions in temperature signals during switching operations, especially when operated as high-side switches.
Innovation Solution
The semiconductor device incorporates additional trenches for routing sense lines and includes conductive pads in the wiring layers to shield these lines, reducing capacitive coupling by maintaining a constant voltage, thus minimizing displacement currents and signal distortions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the temperature sensor is connected to the sense circuit via strip lines formed by wiring layers, then the temperature signal can be transmitted, but significant capacitive coupling occurs between the contact layer and wiring layers causing displacement currents that distort the temperature signal
Solution Approach 1:
A shielding structure (conductive layer or trench filling) is introduced as an intermediary element between the contact layer and the sense lines. This shielding structure acts as a mediator that blocks the capacitive coupling path, preventing displacement currents from distorting the temperature signal while allowing the temperature signal to pass through unaffected.
Solution Approach 2:
The patent segments the sensing path by introducing separate functional layers: the sense lines, the shielding structure, and the contact layer are divided into distinct segments. This segmentation isolates the temperature signal path from the power switching path, eliminating the harmful capacitive coupling between them.
2Reliability
If the contact layer is made thick to provide good contact with external load terminals, then contact reliability improves, but capacitive coupling with subjacent wiring layers increases causing more displacement currents
Solution Approach 1:
The shielding structure serves as an intermediary barrier between the thick contact layer and the wiring layers. It maintains the necessary contact thickness for reliability while blocking the capacitive coupling field lines, thus preventing displacement currents without compromising contact performance.
3Ease of operation
If the sense lines are routed through wiring layers to connect the temperature sensor and sense circuit, then electrical connection is achieved, but the parallel arrangement with contact layer creates parasitic capacitances
Solution Approach 1:
The patent transitions the sense lines from a planar routing through wiring layers to a vertical routing through trenches. This dimensional change allows the sense lines to pass through the substrate in the vertical direction, separating them from the parallel contact layer and eliminating the parasitic capacitance issue while maintaining electrical connectivity.
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 significantly improves temperature sensing accuracy by reducing capacitive coupling and displacement currents, enhancing the reliability of temperature measurements and protection circuits in power semiconductor switches.
Implementation Method 1
a significant capacitive coupling occurs, particularly between the contact layer and the subjacent wiring layer
Data Source
AI summary
A semiconductor device includes a semiconductor body, at least one wiring layer disposed on the semiconductor body and a field effect transistor integrated in the semiconductor body. The field effect transistor has a plurality of gate electrodes residing in corresponding gate trenches formed in the semiconductor body. A first circuit is integrated in the semiconductor body adjacent to the field effect transistor, and a second circuit is integrated in the semiconductor body remote from the first circuit. A first additional trench is formed in the semiconductor body and includes at least one connecting line which electrically connects the first circuit and the second circuit. The semiconductor device also includes at least one conductive pad formed in the at least one wiring layer. The at least one conductive pad is arranged to at least partially cover the first additional trench to form a shielding of the at least one connecting line.