Bonded Contact Pad Redundancy for Void-Tolerant Semiconductor Stacks
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Solution Overview
Problem
In stacked semiconductor structures, direct bonding without adhesives can lead to voids and faults at the bonding interface, which can inhibit reliable electrical connections between contact pads, affecting device yield and performance.
Innovation Solution
Implementing electrical redundancy by providing redundant contact pads with sufficient spacing to overcome voids and faults, and using conductive lines or traces to short unconnected pads to maintain electrical connections, along with optional circuitry for selective path switching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If direct bonding without adhesive is used to stack semiconductor elements, then manufacturing complexity and material cost are reduced, but voids and faults at the bonding interface increase, reducing electrical connection reliability
Solution Approach 1:
The patent implements preliminary action by providing redundant contact pads before bonding occurs. The redundant pads are pre-configured with sufficient spacing to account for potential voids and faults that may form during direct bonding, ensuring that if primary connections fail, alternative paths are already in place to maintain electrical connectivity.
Solution Approach 2:
The patent applies parameter changes by modifying the spacing between contact pads to be sufficiently large to overcome potential voids and faults. This parameter adjustment ensures that redundant pads can establish reliable electrical connections even when bonding defects occur, thereby improving connection reliability without requiring adhesive materials.
2Reliability
If redundant contact pads with sufficient spacing are provided to overcome voids and faults, then electrical connection reliability is improved, but device area and routing complexity increase
Solution Approach 1:
The patent applies local quality by implementing redundancy selectively rather than uniformly across the entire device. Redundant contact pads are provided at specific locations where voids and faults are most likely to occur, with spacing optimized for those critical areas. This localized approach maintains reliability while minimizing the overall area increase.
3Reliability
If contact pads are spaced apart to overcome bonding interface voids, then electrical connection reliability is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent uses preliminary action by pre-establishing redundant contact pad configurations during the design and fabrication process, before actual bonding occurs. The redundant pads are positioned with sufficient spacing to account for expected void formation, eliminating the need for post-bonding adjustments and reducing precision requirements during the bonding process itself.
Data Source
AI summary
An element that is configured to bond to another element is disclosed. A first element that can include a first plurality of contact pads on a first surface. The first plurality of contact pads includes a first contact pad and a second contact pad that are spaced apart from one another. The first and second contact pads are electrically connected to one another for redundancy. The first element can be prepared for direct bonding. The first element can be bonded to a second element to form a bonded structure. The second element has a second plurality of contact pads on a second surface. At least one of the second plurality of contact pads is bonded and electrically connected to at least one of the first plurality of contact pads.