Optical Sensor Deep Trench Isolation and Protruding Passivation
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Solution Overview
Problem
Existing optical sensors lack sufficient light sensitivity, which limits their performance in various applications.
Innovation Solution
The optical sensor design includes a substrate with a sensing region surrounded by a deep trench isolation structure and a passivation layer with protruding portions, which disperses incident light to increase the length of transmission paths and enhance quantum efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional optical sensor structures are used, then manufacturing is simpler, but light sensitivity is insufficient
Solution Approach 1:
The optical sensor divides the sensing region into multiple segments with different well depths (first, second, and third wells at different depths) and uses a deep trench isolation structure to segment different sensing regions. This segmentation allows photons of different wavelengths to be detected at optimal depths, improving light sensitivity without requiring a complete redesign of the sensor architecture.
Solution Approach 2:
The patent introduces vertical dimensionality by creating wells at multiple depth levels (first depth, second depth, third depth) within the substrate. This multi-level vertical structure enables photons to be detected at different depths corresponding to different wavelengths, enhancing light sensitivity by utilizing the depth dimension rather than only horizontal expansion.
2Reliability
If the sensing region is enlarged to capture more light, then light sensitivity improves, but crosstalk between adjacent regions increases
Solution Approach 1:
The deep trench isolation structure extracts and removes the harmful effect of crosstalk by creating deep isolation trenches between adjacent sensing regions. These trenches physically separate the sensing regions at depth, preventing charge carrier diffusion and optical crosstalk while allowing each sensing region to be sufficiently large for high light sensitivity.
Solution Approach 2:
The deep trench isolation structure acts as an intermediary barrier between adjacent sensing regions. It provides physical and electrical isolation, mediating the interaction between neighboring regions by blocking charge carrier diffusion and optical signals, thereby eliminating crosstalk while maintaining large sensing region areas.
3Reliability
If deeper wells are used to detect longer wavelength photons, then quantum efficiency improves, but manufacturing precision requirements increase
Solution Approach 1:
The patent segments the wavelength detection range into multiple depth levels, with first, second, and third wells positioned at different depths to detect different wavelength ranges. This segmentation allows each well to be optimized for specific wavelength detection, improving quantum efficiency for long-wavelength photons while distributing the manufacturing precision requirements across multiple shallower structures rather than requiring one extremely deep well.
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
This design improves the quantum efficiency of the optical sensor by increasing the length of transmission paths for incident light, thereby enhancing light sensitivity and overall performance.
Implementation Method 1
a passivation layer with protruding portions, which disperses incident light to increase the length of transmission paths
Implementation Method 2
an optical sensor is used to convert an optical image focused on the image sensor into an electrical signal
Data Source
AI summary
An optical sensor includes a substrate, a first/second/third well disposed in a sensing region, a deep trench isolation structure, and a passivation layer. The substrate has a first conductivity type and includes the sensing region. The first well has a second conductivity type and a first depth. The second well has the second conductivity type and a second depth. The third well has the first conductivity type and a third depth. The deep trench isolation structure is disposed in the substrate and surrounding the sensing region, wherein the depth of the deep trench isolation structure is greater than the first depth, the first depth is greater than the second depth, and the second depth is greater than the third depth. The passivation layer is disposed over the substrate, wherein the passivation layer includes a plurality of protruding portions disposed directly above the sensing region.