Dielectric Optical Component for Wavelength-Selective CMOS Sensing
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Solution Overview
Problem
Conventional CMOS sensors lack efficient wavelength filtering capabilities, leading to reduced sensitivity and increased manufacturing costs due to the need for complex and expensive techniques such as diffractive light trapping pixels and III-V semiconductor nanowires.
Innovation Solution
A dielectric structure with electrically conducting layers and openings is used to selectively transmit electromagnetic radiation of a specific wavelength, creating constructive interference and enhancing optical absorption in a silicon substrate, thereby increasing sensitivity without the need for complex filtering or micro-structuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a thick photon absorption layer is used to improve absorption efficiency, then optical absorption is improved, but manufacturing cost increases due to expensive equipment requirements
Solution Approach 1:
A dielectric layer is introduced as an intermediary between the incident light and the silicon photodetector. This dielectric layer acts as a mediator that enhances light coupling into the photodetector through constructive interference of edge diffracted and spherical waves, improving absorption efficiency without requiring a thicker silicon substrate, thus avoiding the need for expensive thick-substrate fabrication equipment
Solution Approach 2:
The patent changes the optical parameters by introducing a dielectric layer with specific refractive index and thickness parameters. The dielectric layer thickness and refractive index are optimized to create constructive interference that enhances light absorption in the photodetector, achieving improved absorption efficiency with standard manufacturing thicknesses
2Ease of manufacture
If conventional CMOS sensors are used without wavelength selective absorption, then manufacturing is simpler, but filtering capacity is lost requiring additional complex filters
Solution Approach 1:
The patent merges the wavelength selective filtering function with the existing dielectric layer structure already present in the CMOS sensor. The dielectric layer simultaneously serves as an optical mediator for enhancing absorption and as a wavelength-selective filter, eliminating the need for separate complex filtering structures and maintaining manufacturing simplicity while adding spectral selectivity
Solution Approach 2:
The dielectric layer is designed to perform multiple functions: it acts as an optical mediator to enhance light coupling, provides wavelength selective filtering, and maintains compatibility with standard CMOS fabrication processes. This multi-functionality eliminates the need for additional specialized filtering components
3Adaptability or versatility
If wavelength selective absorption is implemented using conventional techniques, then filtering capacity is improved, but device complexity increases due to complex manufacturing techniques
Solution Approach 1:
The dielectric layer serves as a simple intermediary structure that implements wavelength selective absorption through constructive interference of edge diffracted and spherical waves. This approach achieves filtering capacity without requiring complex manufacturing techniques, as the dielectric layer can be deposited using standard semiconductor fabrication processes
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 solution achieves high photodetection for a selected wavelength while reflecting other wavelengths, increasing photon-generated charge carriers and sensitivity, as demonstrated by simulations showing a strong optical hotspot and enhanced optical power in the silicon substrate.
Implementation Method 1
enhancing optical absorption in a silicon photodetector through constructive interference of edge diffracted and spherical waves
Implementation Method 2
edge diffracted and spherical waves
Implementation Method 3
Wavelength selective absorption has been proposed in literature by using techniques such as diffractive light trapping pixels
Implementation Method 4
Some CMOS sensors operate on the photoelectric effect, which converts incident photons into electrical charges generating an electrical voltage
Data Source
AI summary
In example embodiments, an optical component includes a dielectric structure having a substantially rectangular cross-section with an upper surface and a lower surface. A first electrically conducting layer is provided on the upper surface, where the first electrically conducting layer has a first opening positioned to accept incoming electromagnetic radiation. The second electrically conducting layer has a second opening positioned to emit electromagnetic radiation, e.g. toward a CMOS sensor pixel in a silicon substrate. The dimensions of the optical component are configured to provide constructive interference for incident radiation of a selected wavelength.