Stacked Light-Receiving Chip Alignment Within the Pixel Region
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Solution Overview
Problem
Existing light-receiving devices face challenges in further downsizing due to the inclusion of alignment marks that do not contribute to functionality, leading to increased device size.
Innovation Solution
The light-receiving device incorporates alignment marks within the pixel region of the first chip, allowing for efficient placement and alignment with corresponding marks on the second chip, enabling precise stacking without increasing the device's size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If alignment marks are provided outside the pixel region for chip stacking alignment, then alignment accuracy is improved, but the device size increases
Solution Approach 1:
The patent merges the alignment mark function with the pixel region by placing alignment marks within the pixel region boundaries. This integration allows the alignment marks to share the same space as functional pixels, eliminating the need for separate dedicated alignment mark areas and thus preventing device size increase while maintaining alignment capability
Solution Approach 2:
The pixel region serves dual purposes: it contains functional sensor pixels for image capture and simultaneously houses alignment marks for chip stacking alignment. This multi-functionality allows the same area to fulfill both imaging and alignment requirements, resolving the contradiction between alignment accuracy and device size
2Area of stationary object
If alignment marks are placed within the pixel region, then device size is reduced, but alignment accuracy may be compromised
Solution Approach 1:
The patent applies local quality by creating specific regions within the pixel region that are dedicated to alignment marks with distinct optical or geometric properties. These localized areas provide high-contrast or geometrically distinctive features that enhance detectability and measurement precision for alignment purposes, ensuring that even though space is constrained, the alignment marks maintain sufficient accuracy
Data Source
AI summary
A light-receiving device includes: a first chip having a pixel region in which a sensor pixel is provided; a second chip including a processing circuit that performs signal processing on a sensor signal outputted from the sensor pixel, the second chip being stacked on the first chip; and a first alignment mark provided in the pixel region of the first chip to correspond to a second alignment mark provided in the second chip.