Stacked Die Assembly Using Substrate Openings Instead of TSVs
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Solution Overview
Problem
Existing semiconductor die packages face challenges in reducing size and cost while accommodating stacked semiconductor dies, as techniques like through-substrate vias (TSVs) and direct chip attach methods are costly and complex.
Innovation Solution
The solution involves a package substrate with an opening extending through it, allowing for the stacking of semiconductor dies with bond pads aligned with the opening, enabling wire bonding to substrate bond pads on the back surface, thereby reducing the need for costly TSVs and bumping processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If through-substrate vias (TSVs) are used to facilitate stacking of semiconductor dies, then the footprint of the package is reduced, but the manufacturing cost increases
Solution Approach 1:
The patent extracts and eliminates the TSV structure from the package design. Instead of forming vias through the substrate to connect stacked dies, the invention uses wire bonds that extend through openings in the substrate to connect bond pads on different dies, thereby removing the need for costly TSV fabrication processes while maintaining the stacked configuration
Solution Approach 2:
The patent introduces wire bonds as an intermediary element to facilitate electrical connection between stacked semiconductor dies. The wire bonds serve as a mediator that connects bond pads on upper dies to substrate bond pads without requiring direct through-substrate via holes, thus reducing manufacturing complexity and cost
2Length of stationary object
If direct chip attach methods (e.g., flip-chip bonding) are used to reduce package height, then the package height is reduced, but the manufacturing cost increases
Solution Approach 1:
The patent employs wire bonds as a lower-cost alternative to expensive flip-chip bumping processes. The wire bonds are simple, inexpensive interconnect elements that can be easily formed using established wire bonding technology, replacing the costly and complex bumping process while achieving the same electrical connection function
3Area of stationary object
If TSVs and direct chip attach methods are used for stacking, then semiconductor dies can be stacked to reduce footprint, but yield and reliability issues arise
Solution Approach 1:
The patent allows bond pads on the semiconductor dies to be directly accessible through openings in the substrate, enabling wire bonds to connect directly to the bond pads without requiring alignment with precise TSV locations. This self-aligning approach reduces the risk of misalignment and connection failures, improving yield and reliability
Data Source
AI summary
Stacked semiconductor dies for semiconductor device assemblies and associated methods and systems are disclosed. In some embodiments, the semiconductor die assembly includes a substrate with an opening extending therethrough. The assembly can include a stack of semiconductor dies attached to the substrate. The stack includes a first die attached to a front surface of the substrate, where the first die includes a first bond pad aligned with the opening. The stack also includes a second die attached to the first die such that an edge of the second die extends past a corresponding edge of the first die. The second die includes a second bond pad uncovered by the first die and aligned with the opening. A bond wire formed through the opening couples the first and second bond pads with a substrate bond pad on a back surface of the substrate.