Inorganic Inter-Die Fill Structures for Low-Stress Multi-Die Composites
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Solution Overview
Problem
Current multi-die integration techniques in IC fabrication face challenges such as high cost, low insertion efficiency, and increased z-height due to mechanical stress from inter-die fill materials and slow/expensive gap-fill deposition methods.
Innovation Solution
The development of a multi-die composite structure with a primary fill structure that directly bonds IC dies to a host substrate, using an inorganic primary fill material with through vias for electrical interconnection, and a secondary fill structure to backfill remnant spaces, reducing stress and improving thermal and mechanical compatibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If epoxy based mold compound is used as inter-die fill material, then ease of manufacture is improved, but mechanical reliability deteriorates due to high stress causing failure
Solution Approach 1:
The patent changes the material parameter from organic epoxy-based mold compound to inorganic materials (such as spin-on-glass, silicon oxide, silicon nitride). This material substitution fundamentally alters the stress characteristics, eliminating the high stress problems associated with epoxy while maintaining ease of manufacture through compatible deposition processes
Solution Approach 2:
The patent employs composite material structures where inorganic fill materials are combined with organic mold compound in a multi-layer configuration. The inorganic layer provides mechanical stability and low stress, while the organic layer provides molding capability, creating a composite solution that resolves the contradiction between ease of manufacture and mechanical reliability
2Reliability
If inorganic material is used to fill inter-die spaces to mitigate stress, then mechanical reliability is improved, but productivity deteriorates due to slow and expensive gap-fill deposition
Solution Approach 1:
The patent applies preliminary action by performing planarization of the substrate surface before depositing the inorganic fill material. This pre-preparation step creates a flat, uniform surface that enables rapid and uniform deposition of the inorganic material, significantly improving deposition speed and reducing process cost while maintaining the stress-mitigation benefits
Solution Approach 2:
The patent changes the deposition process parameters by using spin-coating techniques for inorganic materials like spin-on-glass, which offer much faster deposition rates compared to traditional PECVD methods. This parameter change in the deposition process restores productivity while maintaining the mechanical reliability benefits of inorganic materials
3Device complexity
If multi-die composite structures are reduced in thickness, then device complexity is reduced, but mechanical reliability deteriorates due to increased stress concentration
Solution Approach 1:
The patent changes the material composition parameter by substituting low-stress inorganic materials for high-stress organic materials. This material parameter change allows the structure to be thinned without proportionally increasing stress concentration, as the inorganic materials maintain structural integrity at reduced thicknesses
Solution Approach 2:
The patent uses composite material layers where inorganic fill materials are strategically positioned in the multi-die structure. These inorganic layers act as stress-distributing elements that prevent stress concentration even as the overall structure is thinned, enabling reduced device complexity without sacrificing mechanical reliability
Data Source
AI summary
Quasi-monolithic multi-die composites including a primary fill structure within a space between adjacent IC dies. A fill material layer, which may have inorganic composition, may be bonded to a host substrate and patterned to form a primary fill structure that occupies a first portion of the host substrate. IC dies may be bonded to regions of the host substrate within openings where the primary fill structure is absent to have a spatial arrangement complementary to the primary fill structure. The primary fill structure may have a thickness substantially matching that of IC dies and/or be co-planar with a surface of one or more of the IC dies. A gap fill material may then be deposited within remnants of the openings to form a secondary fill structure that occupies space between the IC dies and the primary fill structure.