Redundant Contact Pad Layout for Void-Tolerant Direct Bonding
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Solution Overview
Problem
In stacked semiconductor devices, direct bonding without adhesives can lead to voids and faults at the bonding interface, which inhibit reliable electrical connections between contact pads, affecting device yield and performance.
Innovation Solution
Implementing electrical redundancy by providing redundant contact pads with increased spacing to ensure connections are maintained even if primary pads are not directly connected due to voids, using conductive lines or traces to short redundant pads and potentially incorporating switches or electronic fuses for selective path management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If direct bonding without adhesive is used to stack semiconductor elements, then manufacturing complexity is reduced and device performance is improved, but voids and faults occur at the bonding interface causing unreliable electrical connections
Solution Approach 1:
The patent applies preliminary action by forming redundant contact pads and conductive traces before the bonding process. These redundant electrical pathways are pre-configured so that if voids or faults occur during direct bonding, alternative connection paths are already in place to maintain electrical connectivity between stacked elements.
Solution Approach 2:
The patent changes the electrical pathway parameters by creating multiple parallel conductive paths with different geometries and locations. By varying the trace routes, pad sizes, and connection points, the design ensures that if one path is compromised by bonding defects, other paths with different physical characteristics can compensate and maintain reliable electrical connection.
2Reliability
If redundant contact pads with increased spacing are implemented, then electrical connection reliability is improved, but device area increases
Solution Approach 1:
The patent segments the electrical connection function into multiple independent pathways distributed across different regions of the device. Instead of relying on a single direct pad-to-pad connection, the conductive traces are segmented into alternative routes that can navigate around voids and defects, providing redundant connectivity without requiring uniformly increased spacing across the entire device.
Solution Approach 2:
The patent transitions from two-dimensional pad alignment to three-dimensional trace routing by conducting traces through multiple metal layers and via holes. This dimensional change allows redundant pathways to be created vertically and laterally, providing alternative connection routes that compensate for bonding interface voids without significantly increasing the device footprint.
3Reliability
If conductive traces and switches are added for path management, then electrical redundancy and reliability are enhanced, but device complexity increases
Solution Approach 1:
The patent applies self-service by designing the redundant trace network to automatically provide alternative pathways without requiring external control or monitoring. The conductive traces are configured so that electrical current naturally flows through available paths based on resistance, and switching elements are designed to fail-open or fail-closed states that automatically route signals through redundant paths when primary paths are compromised.
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.