Wafer Edge Die Patterning for Accurate Die Attach Referencing
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Solution Overview
Problem
Conventional die attach processes face challenges in accurately selecting and positioning semiconductor dies due to their small size, making it difficult to distinguish between functional dies used as auto-referencing targets, leading to incorrect selection failures that are hard to detect visually and often occur late in the manufacturing process.
Innovation Solution
The implementation of unique die patterning on incomplete dies along the wafer edge, using a marking and bond pad array formed via photolithography, allows for precise auto-referencing by a die attach machine, reducing the risk of incorrect selection through triangulation and visual verification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional die attach processes are used without unique patterning, then the manufacturing process is simpler and faster, but the accuracy of die selection and positioning deteriorates due to inability to distinguish functional dies
Solution Approach 1:
The patent applies preliminary action by forming unique markings and bond pad arrays on incomplete dies during the wafer fabrication stage, before the dies are separated and packaged. This pre-established patterning enables the die attach machine to easily identify and triangulate reference dies during assembly, solving the selection accuracy problem without adding complexity to the later packaging process.
2Reliability
If unique die patterning is implemented on incomplete dies, then the accuracy of auto-referencing improves through triangulation, but the fabrication process time and cost increase
Solution Approach 1:
The patent merges the formation of unique markings with the existing bond pad array fabrication process. Both features are created using the same photolithography steps and materials that are already part of the standard manufacturing flow, thereby establishing reference patterns without requiring additional process time or resources.
3Ease of operation
If functional dies are used as auto-referencing targets, then the die attach process can proceed, but incorrect selection failures occur that are difficult to detect visually
Solution Approach 1:
The patent applies local quality by placing distinctive markings and unique bond pad array configurations specifically on incomplete dies at the wafer periphery, while leaving functional dies with standard patterns. This localized differentiation enables visual verification systems to easily distinguish reference dies from functional dies, preventing incorrect selection without affecting the functionality of packaged dies.
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 method enhances the accuracy of die attach processes, reduces the risk of errors, and enables early detection of positioning mistakes, while maintaining minimal impact on fabrication time and cost, scalable to advanced technology nodes.
Implementation Method 1
using a marking and bond pad array formed via photolithography
Data Source
AI summary
Systems, devices, and methods for providing unique die patterning are provided herein. A wafer substrate can include a plurality of individual semiconductor dies and a plurality of incomplete dies arranged along an edge of the wafer substrate. Each of the individual semiconductor dies and each of the incomplete dies can include a bond pad array. Each of a subset of the incomplete dies can also include a marking that may be identical or generally similar to the bond pad array. The subset of the incomplete dies, each of which includes both the bond pad array and the marking, can serve as target sites for a die attach machine during an auto-referencing process. In some embodiments, the bond pad arrays and the markings on the subset of the incomplete dies are formed via a photolithography patterning process using the same reticle.