3DIC Hybrid Bonding Structure for Fine-Pitch Interconnects
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Solution Overview
Problem
Existing semiconductor technologies face challenges in achieving smaller form factors, higher integration density, and lower power consumption, particularly in stacked semiconductor devices, where manufacturing defects such as solder bridging hinder the closer spacing of conductive interconnects.
Innovation Solution
A hybrid bonding process using concave contact pads and convex connectors in a 3D integrated circuit structure, where concave contact pads on one wafer or die contain the material of convex connectors during bonding, reducing the risk of defects and allowing for closer spacing of interconnects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional bonding processes are used with standard contact pads, then manufacturing simplicity is maintained, but solder bridging defects occur and prevent closer spacing of interconnects
Solution Approach 1:
The contact pad is designed with an asymmetric recessed cavity structure that is complementary to the protruding connector shape. This asymmetric geometry ensures that the connector material is contained within the cavity during bonding, preventing lateral flow and solder bridging while enabling closer spacing between adjacent interconnects.
Solution Approach 2:
The recessed cavity acts as an intermediary structure between the contact pad and the connector. It provides a controlled interface that guides the connector material into the cavity during bonding, mediating the interaction between the two components and preventing direct contact between adjacent connectors that would cause bridging.
2Productivity
If closer spacing of conductive interconnects is achieved, then I/O density increases, but the risk of solder bridging defects increases
Solution Approach 1:
The asymmetric recessed cavity design provides physical containment for connector material, allowing interconnects to be spaced closer together without increasing the risk of solder bridging. The cavity walls act as barriers that prevent lateral flow of molten solder even at reduced pitch.
Solution Approach 2:
The recessed cavity provides localized containment exactly where the connector material needs to be controlled during bonding. This local quality enhancement at the contact pad interface enables closer spacing globally across the entire interconnect array without compromising reliability.
3Manufacturing precision
If hybrid bonding with concave contact pads is used, then manufacturing precision and I/O density improve, but process complexity increases
Solution Approach 1:
The recessed cavity structure is formed in advance during the contact pad fabrication process, before the actual bonding operation. This preliminary action prepares the contact pad with the exact geometry needed to contain the connector material, simplifying the bonding process itself by eliminating the need for complex real-time control.
Solution Approach 2:
The recessed cavity structure is self-aligning and self-containing during bonding. The geometry of the cavity automatically guides the connector material into the correct position and contains it during melting and bonding, eliminating the need for complex external alignment or containment mechanisms.
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 I/O density and improves yield by minimizing manufacturing defects like solder bridging, enabling smaller pitch and more efficient electrical connections between stacked semiconductor wafers or dies.
Implementation Method 1
heating and pressing to bond the bonding layers together
Implementation Method 2
heating and pressing to bond the bonding layers together
Data Source
AI summary
An embodiment bonded integrated circuit (IC) structure includes a first IC structure and a second IC structure bonded to the first IC structure. The first IC structure includes a first bonding layer and a connector. The second IC structure includes a second bonding layer bonded to and contacting the first bonding layer and a contact pad in the second bonding layer. The connector extends past an interface between the first bonding layer and the second bonding layer, and the contact pad contacts a lateral surface and a sidewall of the connector.