Integrated Optical Sensor Angular Dependence Reduction
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Solution Overview
Problem
Existing optical sensors, particularly those using interference and plasmonic filters, exhibit significant angular dependence in their transmission characteristics, which affects performance when light incidence angles change, and current solutions are bulky and not fully integrated.
Innovation Solution
An integrated optical sensor design featuring a semiconductor substrate, integrated circuit, dielectric layer, wiring, and a structured diffuser layer that scatters light to a Lambertian distribution, reducing angular dependence and allowing for wafer-level integration with optical filters, eliminating the need for external apertures or diffusers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If interference filters are used in optical sensors, then optical filtering performance is improved, but angular dependence of transmission characteristics increases
Solution Approach 1:
The filter structure is divided into multiple discrete layers (first dielectric layer, metal layer, second dielectric layer) with specific optical properties. Each layer segment contributes to the overall filtering performance while the layered segmentation enables independent optimization of angular dependence characteristics.
Solution Approach 2:
The patent employs a composite filter structure combining dielectric materials and metal layers. This composite approach integrates the high selectivity of dielectric interference filters with the angular insensitivity of plasmonic metal nanostructures, achieving both optical filtering performance and reduced angular dependence.
2Adaptability or versatility
If external aperture and diffusor are added to reduce angular dependence, then angular dependence is reduced, but device complexity and size increase
Solution Approach 1:
The patent merges the filter structure with the sensor substrate by directly forming the layered filter structure (dielectric and metal layers) on the sensor chip. This integration eliminates the need for separate external aperture and diffusor components, reducing device complexity while maintaining angular insensitivity through the integrated plasmonic-dielectric structure.
Solution Approach 2:
The patent transitions from a three-dimensional external optical assembly (aperture + diffusor) to a two-dimensional integrated planar filter structure on the sensor surface. This dimensional reduction integrates optical filtering and angular insensitivity functions directly into the sensor chip, simplifying the overall device architecture.
3Measurement precision
If interference filters are designed for parallel incident light, then transmission performance is optimized, but performance degrades under diffusive incident light
Solution Approach 1:
The patent changes the optical parameters of the filter structure by incorporating metal layers with specific plasmonic properties alongside dielectric layers. This parameter modification enables the filter to maintain high transmission performance for parallel light while simultaneously achieving insensitivity to incident angle variations, improving performance under diffusive light conditions.
4Productivity
If wafer level integration is implemented, then manufacturing efficiency is improved, but integration of optical filters with reduced angular dependence becomes more difficult
Solution Approach 1:
The patent performs preliminary actions by pre-forming the layered filter structure (dielectric and metal layers) directly on the sensor wafer during the semiconductor manufacturing process. This preliminary integration of optical filters enables subsequent wafer-level processing and simplifies final assembly, maintaining manufacturing efficiency while achieving complex optical functionality.
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
The integrated optical sensor achieves reduced wavelength shift and improved performance for true color and ambient light sensors with reduced angular dependence, fabricated using CMOS-compatible processes at minimal additional cost, and integrates a diffuser for consistent light scattering across a wide range of angles.
Implementation Method 1
a structured filter layer (7) arranged on the diffuser and adapted for diffused incident light
Implementation Method 2
The diffuser is adapted for defused incident light according to the principles of geometric scattering
Implementation Method 3
Interference filters consists of alternating layers of dielectric materials and thin metal films with varying index of refraction
Implementation Method 4
Interference filters consists of alternating layers of dielectric materials and thin metal films with varying index of refraction
Implementation Method 5
plasmonic colour filters have become available which employ surface-plasmon based nanostructures
Data Source
Figure 1~2
Figure 3~5
Figure 6
AI summary
An integrated optical sensor comprises a semiconductor substrate (1), an integrated circuit (2), a dielectric layer (6), a wiring (4), a structured filter layer (7) and a diffuser (10). The semiconductor substrate (1) has a main surface (11) and the integrated circuit (2) is arranged in the substrate (1) at or near the main surface (11). Furthermore, the integrated circuit (2) comprises at least one light sensitive component (3). The dielectric layer (6) comprises at least one compound of the semiconductor material. The dielectric layer (6) is arranged on or above the main surface (11). The wiring (4) is arranged in the dielectric layer (6) and provides an electrical connection to the integrated circuit (2), i.e. the wiring is connected to the integrated circuit (2). The structured filter layer (7) is arranged on the dielectric layer (6) and faces the at least one light sensitive component (3), i.e. the diffusor (10) is positioned over the structured filter layer (7). In particular, the structured filter layer (7) is adapted for diffused incident light. The diffuser (10) is arranged on the structured filter layer (7).