InFO Redistribution Alignment Marks for Precise Package Overlay
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Solution Overview
Problem
Integrated fan-out packages face challenges in achieving precise alignment and reliable manufacturing due to signal noise and alignment failure rates, which affect the integration density and efficiency of electronic components.
Innovation Solution
The implementation of a redistribution structure with conductive vias and alignment marks, including a grid pattern configuration for the alignment marks, enhances overlay accuracy and reduces signal noise, ensuring precise formation of subsequent elements and improving the reliability of the InFO package.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional alignment methods are used in integrated fan-out packages, then manufacturing process is simpler, but overlay accuracy deteriorates and alignment failure rates increase
Solution Approach 1:
The patent applies preliminary action by forming alignment marks on the encapsulant surface before subsequent redistribution structure fabrication steps. These pre-formed alignment marks serve as reference features for later alignment operations, ensuring accurate positioning of conductive vias and routing patterns without requiring complex real-time alignment systems.
Solution Approach 2:
The patent introduces alignment marks as intermediary reference features between the encapsulant and the redistribution structure. These alignment marks act as mediators that enable precise alignment by providing detectable reference points for positioning subsequent layers, thereby improving overlay accuracy without directly modifying the fundamental manufacturing process complexity.
2Reliability
If alignment marks are not physically contacted with encapsulant, then manufacturing process is easier, but alignment reliability deteriorates due to signal noise
Solution Approach 1:
The patent merges the alignment mark structure with the encapsulant by establishing physical contact between them. This integration combines the alignment reference function with the encapsulant substrate, creating a unified structure that reduces signal noise and improves alignment reliability while avoiding the need for separate alignment mechanisms.
Solution Approach 2:
The alignment marks serve self-service by being formed directly on the encapsulant surface and providing their own reference function. The encapsulant itself becomes part of the alignment system through the physically contacted alignment marks, eliminating the need for external alignment references and simplifying the overall manufacturing process.
3Quantity of substance
If minimum feature size is reduced to increase integration density, then component integration density improves, but manufacturing precision deteriorates due to smaller tolerances
Solution Approach 1:
The patent applies segmentation by dividing the alignment function into distinct alignment marks that are separate from the functional circuit elements. This segmentation allows the alignment marks to be optimized for detection and positioning purposes with larger, more tolerant features, while the functional elements can maintain smaller feature sizes for high integration density without compromising alignment precision.
Data Source
AI summary
An integrated fan-out (InFO) package includes a die, a plurality of conductive structures aside the die, an encapsulant laterally encapsulating the die and the conductive structure, and a redistribution structure. The redistribution structure is disposed on the encapsulant. The redistribution structure includes a plurality of routing patterns, a plurality of conductive vias, and a plurality of alignment marks. The routing patterns and the conductive vias are electrically connected to the die and the conductive structures. The alignment marks surround the routing patterns and the conductive vias. The alignment marks are electrically insulated from the die and the conductive structures. At least one of the alignment marks is in physical contact with the encapsulant, and vertical projections of the alignment marks onto the encapsulant have an offset from one another.