Bonding Pad Segmentation for Probe Mark Isolation
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Solution Overview
Problem
As semiconductor pressure sensors shrink in size, the formation of probe marks during testing can lead to bonding failures due to the small size of bonding pads, causing wire bonding issues and potential electrical conductivity problems, affecting the reliability of connections between the bonding pads and external circuits.
Innovation Solution
A silicon structure design where the substrate exposure part, not covered by the protective layer, is positioned at the outer edge of the bonding pad within the pad opening pattern, preventing the wiring conductor from being exposed and allowing for a distinct probe contact area that avoids probe mark overlap during wire bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the bonding pad size is reduced to decrease sensor size, then the sensor miniaturization is achieved, but the probe mark formation during testing causes bonding failures
Solution Approach 1:
The bonding pad area is segmented into two functional zones: a probe contact area for wafer-level testing and a wire bonding area for final assembly. This segmentation allows the probe mark to be confined to a specific region that does not interfere with the wire bonding process, thereby maintaining bonding reliability despite reduced overall pad size
Solution Approach 2:
Different regions of the bonding pad are assigned different functions and properties. The probe contact area is positioned at a corner or edge where probe marks naturally form, while the wire bonding area is positioned away from this region. This local differentiation ensures that the harmful probe marks do not affect the critical wire bonding locations
2Volume of moving object
If the bonding pad size is reduced, then the sensor miniaturization is achieved, but the wire bonding position overlaps with the probe mark position
Solution Approach 1:
The bonding pad is divided into distinct probe contact area and wire bonding area, with the wire bonding area specifically positioned away from corners and edges where probe marks form. This spatial segmentation ensures that even in miniaturized sensors, the wire bonding position does not overlap with probe mark position
Solution Approach 2:
The pad opening pattern is designed in advance to expose the bonding pad at specific locations that are predetermined to be free from probe mark formation. This preliminary design ensures that subsequent wire bonding operations can be performed at optimal positions without risk of probe mark interference
Data Source
AI summary
A silicon structure includes a silicon substrate having an electric element; a wiring conductor and a bonding pad, connecting the electric element and an external circuit; a protective layer disposed on the silicon substrate; and a pad opening pattern provided in the protective layer to exposed the bonding pad, wherein a probe mark position and a wire bonding position differ, without increasing the size of the bonding pad in plan view. A substrate exposure part, which is not covered with the protective layer, is provided at part of an outer edge of the bonding pad disposed inside the pad opening pattern in the protective film, and the wiring conductor is not exposed through substrate exposure part.