SiC Current Sensing Layout to Limit Heat Escape Error
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The detection accuracy of current values in semiconductor devices is compromised due to differences in heat dissipation between the current sensing and source portions, caused by variations in the placement and size of bonding wires, leading to errors in on-resistance.
Innovation Solution
A SiC semiconductor device design where the current sensing portion is positioned below the sensing-side surface electrode, avoiding direct placement under the wiring member joint, with an interlayer insulating film and passivation film to maintain a fixed distance and prevent heat escape, ensuring accurate current detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the current sensing portion is formed smaller in area than the source portion to achieve appropriate sensing ratio, then the detection accuracy is improved, but the occupation area of bonding wire becomes large causing heat escape and on-resistance error
Solution Approach 1:
The patent positions the current sensing portion in a specific spatial location beneath the sensing-side surface electrode but away from the bonding wire joint part. This spatial arrangement in the vertical dimension allows the sensing portion to maintain small area for accurate sensing while avoiding the harmful thermal effects concentrated at the bonding wire attachment point.
Solution Approach 2:
The patent creates different thermal environments for different portions of the device. The current sensing portion is positioned in a location with controlled heat escape characteristics, while the source portion and bonding wire joint area have different thermal properties. This local differentiation allows each region to operate under optimal thermal conditions.
2Area of stationary object
If the current sensing portion is positioned directly under the bonding wire joint for compact layout, then device area is reduced, but shock from wiring member joining causes cell breakage
Solution Approach 1:
The patent positions the current sensing portion away from the bonding wire joint part in advance, creating a buffer zone that cushions against mechanical shock during the wire bonding process. This preemptive spatial arrangement prevents direct transmission of joining shock to the sensitive cell structure.
Solution Approach 2:
The patent utilizes the vertical dimension beneath the sensing-side surface electrode to position the current sensing portion at a location that is both compact and protected. This spatial arrangement in the cross-sectional dimension achieves area efficiency while providing mechanical protection from bonding wire joint shocks.
3Manufacturing precision
If the current sensing portion is positioned away from the bonding wire joint to avoid heat escape, then on-resistance accuracy is improved, but the layout complexity increases
Solution Approach 1:
The sensing-side surface electrode structure serves multiple functions: it provides the sensing signal output, supports the bonding wire joint, and defines the spatial position of the current sensing portion. This multi-functionality allows the patent to achieve proper thermal separation without adding separate positioning structures, thereby managing layout complexity.
Solution Approach 2:
The patent combines the current sensing portion positioning with the existing sensing-side surface electrode layout. By integrating the sensing portion placement into the overall electrode design rather than treating it as a separate constraint, the patent achieves on-resistance accuracy while minimizing additional layout complexity.
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 design improves the detection accuracy of current values by minimizing errors in on-resistance and enhancing the reliability of current sensing, while allowing for space-saving and efficient manufacturing processes.
Implementation Method 1
heat generated at the second unit cell from escaping while being preferentially transmitted to the wiring member
Data Source
AI summary
A SiC semiconductor device is provided that is capable of improving the detection accuracy of the current value of a principal current detected by a current sensing portion by restraining heat from escaping from the current sensing portion to a wiring member joined to a sensing-side surface electrode. The semiconductor device 1 includes a SiC semiconductor substrate, a source portion 27 including a principal-current-side unit cell 34, a current sensing portion 26 including a sensing-side unit cell 40, a source-side surface electrode 5 disposed above the source portion 27, and a sensing-side surface electrode 6 that is disposed above the current sensing portion 26 and that has a sensing-side pad 15 to which a sensing-side wire is joined, and, in the semiconductor device 1, the sensing-side unit cell 40 is disposed so as to avoid being positioned directly under the sensing-side pad 15.