Image Sensor Mask Openings for Pixel Cross-Talk Isolation
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Solution Overview
Problem
Image sensors experience optical cross-talk between adjacent pixels, compromising performance, especially when applied to optical under-display fingerprint sensing technology, and components at the periphery are sensitive to light, generating interference signals.
Innovation Solution
An image sensor with a mask having an opening in the topmost metal layer that allows light to reach the light collection region while blocking interference between adjacent pixels, using a CMOS image sensor with a metal stacked layer and a microlens to enhance fingerprint sensing accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a mask with an opening is added to block optical cross-talk, then optical cross-talk is reduced, but device complexity increases
Solution Approach 1:
The mask is segmented with openings at specific positions corresponding to the light collection region, allowing light to pass through while blocking adjacent pixel interference. This segmentation approach reduces optical cross-talk by creating distinct light paths for each pixel.
Solution Approach 2:
The mask serves multiple functions: it blocks optical cross-talk between adjacent pixels, defines the light collection region, and maintains structural support for the metal stacked layer. By combining multiple functions into a single component, the patent avoids adding excessive complexity.
2Object-affected harmful factors
If the periphery components are kept optically dark to prevent interference, then interference signals are reduced, but manufacturing complexity increases
Solution Approach 1:
The light blocking function for periphery components is merged with the mask structure. The mask extends to cover peripheral areas and blocks light from reaching non-light-collection regions, eliminating the need for separate light blocking components and simplifying manufacturing.
3Measurement precision
If light is concentrated on the light collection region to improve photoelectric conversion, then sensing accuracy is improved, but risk of overexposure increases
Solution Approach 1:
The mask has different properties in different regions: it has openings at the light collection region to concentrate light and improve photoelectric conversion, while being opaque in peripheral regions to block excess light. This local quality differentiation allows simultaneous optimization of sensing accuracy and overexposure prevention.
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
Reduces optical cross-talk, enhances fingerprint sensing accuracy, and maintains reliability without additional costs, by concentrating light energy on the light collection region for improved photoelectric conversion.
Implementation Method 1
the mask (110) having an opening (124). The opening (124) allows light waves to reach the light collection region (104)
Implementation Method 2
neighboring the front side of the substrate. The opening allows light waves to reach the light collection region (104) so as to be converted into photogenerated charge carriers
Data Source
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AI summary
The present invention discloses an image sensor and a related handheld device. The image sensor includes: a substrate doped to a first conductivity type and the substrate having a front side and a back side, the back side being opposite to the front side; a light collection region disposed in the substrate, neighboring the front side of the substrate, and arranged to collect photogenerated charge carriers, with the light collection region doped to a second conductivity type opposite to the first conductivity type; and a mask disposed over the substrate and the mask having an opening, allowing light waves to reach the light collection region through the opening and be converted into the photogenerated charge carriers.