Multi-Die IC Edge Shaping for Thermal Crack Mitigation
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Solution Overview
Problem
Existing IC die disintegration techniques face challenges such as high cost, lower insertion efficiency, and increased z-height due to high stress during thermal cycling, which can induce cracks in multi-die composite structures, reducing device yield.
Innovation Solution
The implementation of quasi-monolithic integrated circuit structures with shaped IC die edges and corners, and a crack barrier layer to mitigate stress and prevent crack propagation, using inorganic gap fill materials and self-aligned voids to manage stress and prevent delamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multi-die composite structures are fabricated with inter-die fill material, then device integration is achieved, but high stress during thermal cycling induces cracks that reduce functional device yield
Solution Approach 1:
The patent applies preliminary action by shaping the IC die edges and corners (e.g., chamfering, radiusing, or rounding) before assembling the multi-die composite structure. This pre-shaping prevents stress concentration from occurring during thermal cycling, thereby preventing crack formation while maintaining device integration. The edge shaping is performed in advance on individual dies before they are bonded together with fill material.
Solution Approach 2:
The patent converts the potentially harmful stress concentration at sharp edges into a beneficial distributed stress pattern by intentionally creating rounded or chamfered edges. This transformation allows the fill material to bond smoothly to the die edges, converting what would be crack initiation points into stress-distributing features that enhance overall structure reliability during thermal cycling.
2Ease of manufacture
If IC die edges are left sharp and angular, then manufacturing simplicity is maintained, but stress concentration occurs during thermal cycling inducing cracks
Solution Approach 1:
The patent applies spheroidality by rounding or radiusing the edges and corners of IC dies instead of leaving them sharp and angular. This curvature eliminates stress concentration points that would form at sharp edges during thermal cycling. The rounded edges allow stress to distribute evenly across the die-edge-to-fill-material interface, preventing crack initiation while remaining compatible with standard manufacturing processes.
3Reliability
If crack barriers and edge shaping are implemented, then crack propagation is prevented, but device complexity increases
Solution Approach 1:
The patent uses preliminary action by performing edge shaping (chamfering, radiusing, or rounding) on IC dies before assembly. This pre-processing step creates a geometric feature that inherently prevents crack propagation into the die, eliminating the need for additional crack barrier layers or complex protective structures. The simplicity of the approach maintains low device complexity while achieving high reliability.
Data Source
AI summary
Multi-die packages including IC die crack mitigation features. Prior to the bonding of IC dies to a host substrate, the IC dies may be shaped, for example with a corner radius or chamfer. After bonding the shaped IC dies, a fill comprising at least one inorganic material may be deposited over the IC dies, for example to backfill a space between adjacent IC dies. With the benefit of a greater IC die sidewall slope and/or smoother surface topology associated with the shaping process, occurrences of stress cracking within the fill and concomitant damage to the IC dies may be reduced. Prior to depositing a fill, a barrier layer may be deposited over the IC die to prevent cracks that might form in the fill material from propagating into the IC die.