Wafer Inspection Chuck Targets for Single-Shot Position Measurement
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Solution Overview
Problem
Existing wafer inspection systems face inefficiencies in throughput due to the need to scan and detect marks on chucks that are displaced beyond the imaging range of the imaging unit, requiring time-consuming processes.
Innovation Solution
A wafer inspection apparatus with a target larger than the chuck's allowable movement range, allowing imaging in a single shot and using a separate imaged portion with multiple marks to determine position and angle, and incorporating a black Mylar sheet for reliable imaging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the mark is formed as a small-diameter hole to be imaged by the imaging unit, then the mark can be detected, but if the chuck is significantly displaced beyond the imaging range, the mark will also be displaced and requires scanning to detect, which takes time and reduces throughput
Solution Approach 1:
The patent transitions from a small-point mark (0D/1D) to a large-area mark (2D) that spans the entire chuck surface. This dimensional expansion allows the mark to remain within the imaging unit's field of view regardless of chuck displacement, eliminating the need for scanning operations and thereby improving throughput while maintaining detection accuracy.
Solution Approach 2:
The large-area mark is divided into multiple segments (first mark and second mark) positioned at different locations on the chuck. This segmentation allows the imaging unit to detect at least one mark segment even when the chuck is displaced, ensuring reliable position detection without requiring the imaging unit to scan the entire movement range.
2Loss of time
If the target is made larger than the allowable movement range of the chuck, then single-shot imaging is possible, but the target covers a larger area that may require more complex imaging
Solution Approach 1:
The patent uses a mark area that is larger than necessary to cover the chuck's movement range. This excessive action ensures that even with displacement, the mark remains fully or partially within the imaging unit's field of view, enabling single-shot imaging. The increased mark size compensates for potential misalignment without requiring complex imaging adjustments.
Data Source
AI summary
A wafer inspection apparatus, a chuck position measurement method, and a target capable of improving a throughput are provided. A wafer inspection apparatus 10 includes a probe card 21, a chuck 22 capable of electrically connecting a wafer W to the probe card 21, a holding portion 23 holding the chuck 22, a target provided on the chuck 22, and an imaging unit 25 imaging the target. The target is formed to be larger than an allowable movement range of the chuck 22 with respect to the holding portion 23 to be able to be imaged with the imaging unit 25 fixed at a predetermined position. A position and an angle of the chuck 22 are determined on the basis of the imaged target.