Barrier Collar Structure for Misaligned Bonded Interconnects
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Solution Overview
Problem
In microelectronic assembly bonding, misaligned conductive interconnect structures can lead to diffusion of conductive materials into dielectric materials, causing performance degradation, leakage, and shorting due to placement inaccuracies and differences in pad sizes, which affects package yield and performance.
Innovation Solution
The implementation of a barrier interface, comprising materials like silicon nitride or air gaps, around conductive interconnect pads to inhibit diffusion, ensuring that conductive materials contact the barrier instead of the dielectric, thereby preventing unwanted diffusion and improving alignment accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If direct bonding technique is used to bond stacked dies or wafers, then bonding strength and electrical connection are improved, but placement accuracy requirements increase and diffusion of conductive material into dielectric occurs due to misalignment
Solution Approach 1:
A barrier collar structure is introduced as an intermediary element between the conductive interconnect pad and the dielectric material. This barrier collar prevents direct contact and diffusion of conductive material into the dielectric when misalignment occurs, while still allowing the direct bonding technique to proceed. The barrier collar acts as a protective mediator that decouples the bonding process from the diffusion problem.
Solution Approach 2:
The barrier collar is formed in advance around the conductive interconnect pad before the bonding process. This preliminary protective structure is already in place when the dies or wafers are aligned and bonded, so it can immediately prevent diffusion if misalignment occurs during bonding or subsequent processing steps.
2Reliability
If fine pitch conductive interconnect structures are used to improve electrical performance, then signal integrity is improved, but misalignment and diffusion problems worsen due to smaller tolerances
Solution Approach 1:
The barrier collar serves as a protective intermediary that specifically addresses the diffusion risk associated with fine pitch structures. Because the barrier collar is formed around the conductive pad, it provides a proportional protective zone that scales with the pad size, making it particularly effective for fine pitch interconnects where diffusion would have the most severe impact on electrical performance.
3Reliability
If barrier interface is added around conductive interconnect pads to prevent diffusion, then reliability is improved, but device complexity and manufacturing steps increase
Solution Approach 1:
The barrier collar is applied locally only around the conductive interconnect pads where diffusion is a problem, rather than creating a global barrier structure across the entire die or wafer surface. This localized approach provides the necessary diffusion protection precisely where needed at the pad-dielectric interface, while leaving the rest of the bonding surface available for direct bonding, thus minimizing the increase in device complexity.
4Manufacturing precision
If barrier interface is added to prevent diffusion, then manufacturing precision requirements are relaxed, but additional manufacturing steps and process complexity are required
Solution Approach 1:
The barrier collar is formed in advance as part of the interconnect structure fabrication process, before the bonding alignment step. By preparing this protective structure preliminarily, the actual bonding process can proceed with relaxed alignment tolerances since the barrier collar will prevent diffusion even if perfect alignment is not achieved. The preliminary formation of the barrier collar decouples the diffusion protection function from the alignment precision requirement.
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 barrier interface effectively reduces or prevents conductive material diffusion into insulating materials, enhancing the reliability and performance of microelectronic assemblies by relaxing placement accuracy requirements and reducing leakage issues.
Implementation Method 1
a barrier interface, comprising materials like silicon nitride or air gaps, around conductive interconnect pads to inhibit diffusion
Data Source
AI summary
Representative implementations of techniques and devices are used to reduce or prevent conductive material diffusion into insulating or dielectric material of bonded substrates. Misaligned conductive structures can come into direct contact with a dielectric portion of the substrates due to overlap, especially while employing direct bonding techniques. A barrier interface that can inhibit the diffusion is disposed generally between the conductive material and the dielectric at the overlap.