Multi-Magnification Probe Alignment for Semiconductor Testing
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Solution Overview
Problem
The process of positioning probes for testing semiconductor wafers is time-consuming and laborious due to the limited depth of field in microscope lenses, causing focus issues and difficulty in aligning the probe tip with the correct device, especially when multiple devices are closely spaced.
Innovation Solution
A probing system with multiple imaging devices providing different magnification levels, allowing for simultaneous video feeds to be combined into a single composite video feed, enabling the operator to align the probe using wide, medium, and narrow field views without constant zooming, which maintains focus and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single microscope lens with limited depth of field is used for probe positioning, then the device complexity is reduced, but the alignment precision deteriorates due to focus issues when multiple devices are closely spaced
Solution Approach 1:
The imaging system is segmented into multiple imaging devices, each with a different magnification level. This allows the operator to view multiple devices at once at a lower magnification to identify the target device, then switch to a higher magnification view to precisely align the probe tip with the selected device, thereby resolving the focus and alignment precision issues without requiring a single complex lens system
Solution Approach 2:
The system transitions from a single two-dimensional view to a multi-dimensional imaging approach by combining multiple imaging devices with different magnifications. This dimensional expansion in the imaging space allows simultaneous visualization of both the broader device array and the specific probe-target alignment, eliminating the need to constantly refocus or change lenses
2Measurement precision
If constant zooming is performed to align the probe tip with the correct device, then the alignment precision improves, but the time required for positioning increases
Solution Approach 1:
The system performs preliminary positioning by displaying multiple devices simultaneously at a lower magnification level, allowing the operator to identify and select the target device before switching to higher magnification for final probe alignment. This preliminary action eliminates the need for repeated zooming and refocusing, significantly reducing the time required for probe positioning while maintaining alignment precision
3Measurement precision
If frequent lens changes are made to adjust magnification, then the alignment precision improves, but the productivity decreases due to repeated adjustments
Solution Approach 1:
Multiple imaging devices with different magnification levels are merged into a single composite video feed that displays all magnification levels simultaneously. This merging allows the operator to perform all alignment operations without changing lenses, as all magnification levels are available at once in the composite view, thereby maintaining alignment precision while eliminating the productivity loss associated with frequent lens changes
4Measurement precision
If high magnification is used to view closely spaced devices, then the measurement precision improves, but the field of view decreases making it difficult to locate the target device
Solution Approach 1:
The visual field is segmented into multiple magnification levels that can be viewed simultaneously in the composite video feed. The operator can see the broader field of view at lower magnification to locate the target device, while also having access to high magnification views to visualize closely spaced devices with precision, thereby resolving the contradiction between field of view and measurement precision
Data Source
AI summary
A semiconductor testing system that includes an plural imaging devices for capturing plural video sequences from a single optical path and concurrently displaying the video sequences for effectively positioning a probe for testing a semiconductor wafer.