Chip Inspection Tray Height Measurement and Focus Control
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Solution Overview
Problem
Current chip inspection systems face challenges in achieving high throughput and accuracy due to the deformation of plastic trays, which causes chips to fluctuate in height, making precise focusing difficult, especially in high-speed inspection scenarios, and there is a lack of comprehensive inspection processes between wafer-level gold bump inspection and final testing.
Innovation Solution
A system utilizing a three-dimensional sensor to measure chip heights, a focus computing unit to determine focusing positions, and an image sensor to inspect chips, allowing for high-throughput defect detection by adjusting focus based on measured height signals, ensuring accurate inspection across varying chip heights and angles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If coarse and fine focus adjusting mechanisms are used to bring chips into focus, then chip focusing accuracy is improved, but inspection throughput decreases
Solution Approach 1:
The patent applies preliminary action by using a three-dimensional sensor to pre-measure the height of each chip before inspection. This height information is obtained in advance and used to pre-position the imaging device, eliminating the need for time-consuming coarse and fine focus adjustment mechanisms during the inspection process itself.
Solution Approach 2:
The patent replaces the mechanical focus adjustment system (coarse and fine focus mechanisms) with an automated positioning system that uses three-dimensional height measurement data. Instead of mechanically adjusting focus during inspection, the system uses the measured height information to automatically position the imaging device at the correct focal plane for each chip.
2Measurement precision
If every chip is inspected individually with focus adjustment, then inspection accuracy is improved, but inspection time increases
Solution Approach 1:
The system performs preliminary height measurement of all chips using a three-dimensional sensor before the actual inspection begins. This advance measurement allows the inspection process to proceed without time-consuming focus adjustments for each individual chip, thereby maintaining high accuracy while reducing total inspection time.
Solution Approach 2:
The patent enables continuous inspection by eliminating the intermittent focus adjustment steps between chips. The imaging device can continuously inspect chips at high speed because the focal position for each chip is predetermined based on the preliminary three-dimensional height measurements, maintaining uninterrupted inspection flow.
3Ease of operation
If plastic trays are used for chip storage, then ease of handling is improved, but chip height stability deteriorates
Solution Approach 1:
The patent applies feedback by using a three-dimensional sensor to measure the actual height of each chip in the plastic tray. This measured height information is fed back to the positioning system, which then adjusts the imaging device's focal position accordingly. This closed-loop approach compensates for the height variations caused by plastic tray deformation while maintaining ease of handling.
Data Source
AI summary
A system for inspecting chips in a tray comprises a three-dimensional sensor, a focus computing unit, an image sensor and a focusing device. The three-dimensional sensor is used to obtain the height signals of surfaces of the chips. The focus computing unit calculates the focusing positions of chips. The surface inspection sensor is used to inspect the surfaces of the chips. The focusing device is used to bring the images of the surfaces of the chips into the focus of the image sensor.