Semiconductor Device Backside Metal Layer Current Distribution
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Solution Overview
Problem
Chip-scale semiconductor devices experience current crowding and local heating due to uneven current distribution, limiting their ability to handle large currents effectively, as the current flows laterally through the substrate, concentrating at the edges of the contacts.
Innovation Solution
Incorporating an electrically floating metal layer on the backside of the semiconductor substrate, which allows current to flow from one contact to another via the metal layer, reducing resistivity and promoting even current distribution by bypassing direct lateral flow through the substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If contacts are located on a common surface of the substrate in a chip-scale package, then the package size is reduced, but current crowding and local heating occur due to uneven current distribution
Solution Approach 1:
The patent introduces a vertical dimension to the current path by placing contacts on opposite surfaces of the substrate (top and bottom surfaces) rather than on the same surface. This dimensional change allows current to flow vertically through the substrate thickness, avoiding the lateral current crowding that occurs when contacts are on the same surface, thereby maintaining small package size while improving current handling capability
Solution Approach 2:
The patent segments the current path into distinct regions by providing first and second contacts on opposite surfaces, creating separate entry and exit points for current. This segmentation distributes the current flow more evenly through the substrate volume, preventing concentration at specific edges or regions, thus resolving the current crowding issue while maintaining compact packaging
2Device complexity
If current flows laterally through the substrate between contacts on the same surface, then the device structure is simple, but current density concentrates at contact edges causing local heating
Solution Approach 1:
The patent transitions from lateral (horizontal) current flow to vertical current flow by positioning contacts on opposite surfaces of the substrate. This dimensional change distributes current throughout the substrate volume rather than concentrating it at lateral edges, significantly reducing local heating while maintaining relatively simple device structure
Solution Approach 2:
The patent employs a composite structure combining the semiconductor substrate with strategically positioned contacts on opposite surfaces. This composite arrangement creates optimized current pathways that distribute current evenly through the material, reducing resistive heating while preserving structural simplicity
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 approach enhances the current handling capability of the device by reducing current crowding and local heating, enabling it to manage larger currents with improved robustness and efficiency.
Implementation Method 1
an electrically floating metal layer forming an ohmic contact on a backside of the semiconductor substrate
Data Source
AI summary
A semiconductor device and a method of making the same. The device includes a semiconductor substrate provided in a chip-scale package (CSP). The device also includes a plurality of contacts provided on a major surface of the substrate. The device further includes an electrically floating metal layer forming an ohmic contact on a backside of the semiconductor substrate. The device is operable to conduct a current that passes through the substrate from a first of said plurality of contacts to a second of said plurality of contacts via the metal layer on the backside.