Self-Aligned Diffusion Barrier for Hybrid Bonded Interconnects
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Solution Overview
Problem
Hybrid bonding in semiconductor devices often results in lateral misalignment of conductive features, leading to metal diffusion into adjacent dielectric material, which is not effectively mitigated by conventional diffusion barriers typically used in BEOL metallization layers, causing reliability issues in interconnect structures.
Innovation Solution
A supplemental diffusion barrier is formed using metallic or chalcogen dopants that react with constituents at the bond interface to create a self-aligned barrier, containing metal diffusion and ensuring the integrity of composite interconnect structures, particularly where misalignment occurs during hybrid bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If hybrid bonding is used to increase interconnect density, then the number of addressable signals increases, but lateral misalignment occurs between bonded conductive features leading to metal diffusion into dielectric material
Solution Approach 1:
A diffusion barrier layer is formed at the bond interface before hybrid bonding occurs. This preliminary barrier prevents metal diffusion into the dielectric material that would otherwise occur due to lateral misalignment between bonded conductive features, thereby maintaining reliability while enabling high interconnect density
Solution Approach 2:
The diffusion barrier layer acts as an intermediary substance between the metal conductive features and the dielectric material. This intermediate layer blocks the harmful interaction (metal diffusion) while allowing the bonding interface to function, resolving the contradiction between high density bonding and metal containment
2Reliability
If conventional diffusion barriers from BEOL metallization are used, then metal diffusion is mitigated in standard interconnect layers, but they are not effective at hybrid bonding interfaces with lateral misalignment
Solution Approach 1:
The diffusion barrier is specifically targeted and formed only at the hybrid bonding interface where metal diffusion is most likely to occur due to lateral misalignment. This localized approach provides effective metal containment at the critical interface without requiring conventional barriers throughout the entire interconnect structure
Solution Approach 2:
The barrier formation process uses specific parameters (temperature, time, dopant concentration) optimized for the hybrid bonding interface environment rather than standard BEOL conditions. This allows the barrier to be effective specifically where needed at the bonding interface with lateral misalignment
3Reliability
If lateral misalignment between bonded conductive features is reduced, then metal diffusion is prevented, but manufacturing precision requirements increase significantly
Solution Approach 1:
Instead of requiring ultra-precise alignment during bonding, the diffusion barrier is formed in advance at the bonding interface. This preliminary barrier provides metal diffusion protection even when lateral misalignment of a few hundred nanometers occurs, significantly relaxing the manufacturing precision requirements
4Device complexity
If no diffusion barrier is present at the bond interface, then the structure is simpler, but metal outdiffusion into dielectric material occurs through the metallization-dielectric interface
Solution Approach 1:
The bondline structure is segmented into distinct functional layers: the dielectric material, the conductive features, and the diffusion barrier layer at the interface. This segmentation isolates the metal diffusion hazard at the interface without complicating the bulk structures, providing targeted protection with minimal added complexity
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
The self-formed diffusion barrier effectively retards metal outdiffusion across the bond interface, enhancing the reliability and longevity of hybrid bonded interconnects by containing metal within the composite interconnect structure, even in the presence of misalignment.
Implementation Method 1
metal diffusion into adjacent dielectric material
Implementation Method 2
metallic or chalcogen dopants that react with constituents at the bond interface to create a self-aligned barrier
Data Source
AI summary
Composite integrated circuit (IC) device structures that include two components coupled through a hybrid bonded composite interconnect structure. The two components may be two different monolithic IC structures (e.g., chips) that are bonded over substantially planar dielectric and metallization interfaces. Composite interconnect metallization features formed at a bond interface may be doped with a metal or chalcogenide dopant. The dopant may migrate to a periphery of the composite interconnect structure and form a barrier material that will then limit outdiffusion of a metal, such as copper, into adjacent dielectric material.