Wafer Crack Stop Structure with Extended Metal Layer
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Solution Overview
Problem
Mechanical dicing processes in wafer manufacturing often result in chipping and crack propagation, which complicates the production of high-quality integrated circuit chips, as existing crack stop structures are not effective in preventing cracks from reaching sensitive areas and are difficult to inspect for defects.
Innovation Solution
A wafer design incorporating a kerf area with a dicing area, a crack stop structure, and a trench, where the metal layer of the crack stop structure extends beyond the crack stop structure towards the dicing area, deflecting laterally propagating cracks perpendicular to the substrate surface and terminating them before reaching the polyimide layer, and additional crack stop patterns are provided under the trench to manage crack energy effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If mechanical dicing processes are used to separate wafers into integrated circuit chips, then productivity is improved by simultaneous processing of multiple chips, but chipping and crack propagation occur that worsen manufacturing precision and reliability
Solution Approach 1:
The wafer is segmented into multiple IC areas separated by kerf areas containing crack stop structures. These structures divide the continuous wafer into isolated regions, preventing cracks from propagating across the entire wafer during mechanical dicing, thereby maintaining manufacturing precision while enabling simultaneous processing of multiple chips
Solution Approach 2:
Crack stop structures serve as intermediary elements positioned between IC areas and dicing areas. These structures intercept and terminate laterally propagating cracks before they reach sensitive IC areas, resolving the contradiction by providing a protective barrier that maintains chip quality during high-productivity mechanical dicing operations
2Reliability
If crack stop structures are added to prevent crack propagation, then reliability is improved by stopping cracks before reaching IC areas, but device complexity increases due to additional structural elements
Solution Approach 1:
Crack stop structures are implemented with local quality by positioning them specifically in kerf areas between IC areas and dicing areas. The structures have varying configurations - some regions have extended metal layers while others have trenches - providing targeted crack protection only where needed, thus improving reliability without unnecessarily increasing overall device complexity
Solution Approach 2:
The crack stop structures utilize the vertical dimension by extending metal layers beyond the crack stop structure towards the dicing area and creating trenches at specific depths. This three-dimensional arrangement provides effective crack termination while optimizing the use of available space, balancing reliability improvement with minimal increase in device complexity
3Reliability
If extended metal layers are used in crack stop structures to deflect cracks, then crack stop effectiveness is improved by deflecting laterally propagating cracks perpendicular to substrate surface, but manufacturing complexity increases due to additional processing steps
Solution Approach 1:
Extended metal layers are formed as part of the preliminary backend-of-line processing steps, creating crack stop structures before final dicing operations. This preliminary action ensures cracks are deflected perpendicular to the substrate surface before they can reach IC areas, improving crack stop effectiveness while integrating the process into existing manufacturing workflows to minimize additional complexity
4Manufacturing precision
If trenches are added between crack stop structure and dicing area to terminate cracks, then manufacturing precision is improved by preventing cracks from reaching polyimide layer, but device complexity increases due to additional structural components
Solution Approach 1:
Trenches are implemented with local quality by positioning them specifically between the crack stop structure and the dicing area, at a depth that terminates cracks before they reach the polyimide layer. This targeted approach ensures manufacturing precision is improved in the critical region where cracks are most likely to propagate, while avoiding unnecessary structural additions in other areas, thus balancing precision improvement with minimal increase in device complexity
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 design effectively prevents chipping and crack propagation, enhancing the quality of integrated circuit devices by ensuring that cracks are deflected and terminated before reaching sensitive areas, and allows for inspection to determine if damage has extended beyond the crack stop structure, thereby improving yield and quality control.
Implementation Method 1
the metal layer of the crack stop structure extends beyond the crack stop structure towards the dicing area, deflecting laterally propagating cracks perpendicular to the substrate surface and terminating them before reaching the polyimide layer
Data Source
AI summary
A wafer has a number of IC areas and a kerf area arranged between the IC areas. The kerf area has a dicing area, a crack stop structure arranged between an IC area and a dicing area, and a trench arranged between the crack stop structure and the dicing area. The crack stop structure includes an extended layer extending beyond the crack stop structure towards the dicing area.