Integrated Substrate Structure for Fine-Pitch Wafer Testing
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Solution Overview
Problem
The challenge lies in developing an integrated substrate structure that can effectively connect and test semiconductor wafers with fine-pitched terminals, as existing circuit substrates struggle to meet the increasing terminal count and pitch requirements of highly integrated devices, necessitating a solution that balances reliability, electrical performance, thinness, stiffness, and cost-effectiveness.
Innovation Solution
The integrated substrate structure incorporates a thin-film redistribution layer coupled with a circuit substrate, featuring a fine redistribution circuitry and a coarse redistribution circuitry, with conductive features such as pillars and pads that form solder joints for electrical connectivity, along with an underfill layer and surface finishing, to create a robust and efficient interconnection system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional circuit substrate is used to connect fine-pitched semiconductor terminals, then the substrate can provide basic mechanical support, but it cannot meet the required pitch and terminal count for highly integrated devices
Solution Approach 1:
The substrate system is divided into two distinct layers: a thin-film redistribution layer with fine-pitched circuitry for high-density interconnections, and a thicker circuit substrate with coarse circuitry for mechanical support and lower-density connections. This segmentation allows each layer to optimize for its specific function, resolving the contradiction between fine pitch requirements and substrate complexity.
Solution Approach 2:
The invention transitions from a single-plane substrate to a multi-layer three-dimensional structure. The thin-film redistribution layer is positioned at a different vertical dimension than the circuit substrate, enabling fine-pitched terminals to be connected through vertical vias and solder joints while maintaining mechanical stability from the lower substrate layer.
2Manufacturing precision
If the substrate is made thinner to meet pitch requirements, then fine-pitched connections are enabled, but structural stiffness and reliability are compromised
Solution Approach 1:
The structural function is separated from the fine-pitch interconnection function. The thin-film redistribution layer provides the fine pitch (50-200 micrometers) necessary for high-density connections, while the thicker circuit substrate (500-1000 micrometers) provides the mechanical stiffness and strength. This functional segmentation resolves the contradiction between thinness for pitch and thickness for strength.
Solution Approach 2:
The substrate system uses composite construction with a thin-film redistribution layer (5-50 micrometers thick) made of flexible materials suitable for fine patterning, bonded to a thicker circuit substrate (500-1000 micrometers thick) made of rigid materials for mechanical support. This composite structure enables both fine pitch and adequate stiffness simultaneously.
3Manufacturing precision
If a thin-film redistribution layer is introduced to achieve fine pitch, then electrical performance and pitch requirements are met, but manufacturing complexity increases
Solution Approach 1:
The thin-film redistribution layer is manufactured using standard semiconductor fabrication processes (deposition, lithography, etching, plating) that are already well-established in the industry. By merging these existing processes into a integrated manufacturing flow and bonding the thin-film layer to the circuit substrate, the invention achieves fine pitch without proportionally increasing manufacturing complexity.
4Reliability
If conductive features with solder joints are used to connect the layers, then reliable electrical connectivity is achieved, but manufacturing steps and process complexity increase
Solution Approach 1:
The conductive features (solder balls, bumps, or pillars) on the thin-film redistribution layer are designed to self-align with the corresponding pads on the circuit substrate during the bonding process. The solder material automatically forms reliable joints through self-fluxing and self-alignment mechanisms, reducing the need for complex alignment systems and manual positioning steps.
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
This configuration enables reliable and efficient electrical testing of semiconductor wafers by transforming the pitch requirements, ensuring good electrical performance, thinness, stiffness, and competitive pricing, while maintaining planarity and reliability.
Implementation Method 1
The conductive features are interposed between the circuit substrate and the redistribution film to be connected to the fine redistribution circuitry and the coarse redistribution circuitry
Data Source
AI summary
An integrated substrate structure includes a redistribution film, a circuit substrate, and a plurality of conductive features. The redistribution film includes a fine redistribution circuitry, a circuit substrate is disposed over the redistribution film and includes a core layer and a coarse redistribution circuitry disposed in and on the core layer. The circuit substrate is thicker and more rigid than the redistribution film, and a layout density of the fine redistribution circuitry is denser than that of the coarse redistribution circuitry. The conductive features are interposed between the circuit substrate and the redistribution film to be connected to the fine redistribution circuitry and the coarse redistribution circuitry. A redistribution structure and manufacturing methods are also provided.