Nanoscale Diffractive Optical Element CMOS Integration
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Solution Overview
Problem
Conventional diffractive optical elements (DOEs) have microscale periodicity greater than 10 times the target wavelength, are complex, and incompatible with CMOS fabrication techniques, leading to inefficiencies and limitations in optical pattern generation and compatibility with electronic devices.
Innovation Solution
A diffractive optical element with nanostructures having a periodicity ranging from 0.75 to 3 times the target wavelength, formed using CMOS-compatible materials like silicon dioxide and silicon nitride, with optimized pillar shapes and refractive indices, and an anti-reflective coating, enabling efficient light diffraction patterns and integration with semiconductor sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional DOEs with microscale periodicity (>10λ) are used, then fabrication complexity is high and CMOS compatibility is poor, but transmission efficiency is maintained
Solution Approach 1:
The patent changes the periodicity parameter from microscale (>10λ) to nanoscale (0.75λ to 3λ), which fundamentally alters both the fabrication compatibility and optical performance. This parameter change enables CMOS compatibility while simultaneously improving transmission efficiency to above 80%
Solution Approach 2:
The patent employs composite material structures combining silicon dioxide substrate with silicon nitride nanostructures, where each material is selected for its CMOS compatibility and optical properties. This composite approach enables fabrication using standard CMOS processes while achieving the desired optical performance
2Ease of operation
If conventional DOEs with multiple height levels are used, then diffraction control is achieved, but device complexity increases
Solution Approach 1:
The patent extracts the essential diffraction control function from the complex multi-height structure and implements it through a simplified single-height nanostructure array. The nanoscale periodicity itself provides the diffraction control without requiring multiple height levels, thereby removing unnecessary structural complexity
Solution Approach 2:
By changing the periodicity to nanoscale range (0.75λ to 3λ), the patent achieves effective diffraction control with a uniform height structure, eliminating the need for multiple height levels while maintaining or improving diffraction performance
3Ease of operation
If metasurfaces with periodicity ~λ/2 are used, then light control is achieved, but transmission efficiency decreases and design complexity increases
Solution Approach 1:
The patent optimizes the periodicity parameter to the range of 0.75λ to 3λ, which is larger than the metasurface value of ~λ/2. This parameter optimization achieves effective light diffraction control while significantly improving transmission efficiency to above 80%, resolving the trade-off between light control and energy loss
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 improved transmission efficiency and reduced light-dot intensity nonuniformity, enabling the generation of fewer higher-order modes and compact, high-performance optical elements suitable for diverse electronic devices, with simplified fabrication and enhanced compatibility with CMOS processing.
Implementation Method 1
Diffractive optical elements (DOEs) generate desired optical patterns by controlling diffraction of light
Implementation Method 2
the diffractive optical element may include an anti-reflective coating formed on at least one of the substrate layer and the nanostructure layer
Data Source
AI summary
A diffractive optical element (DOE) includes a substrate layer; and a nanostructure layer comprising nanostructures having a predetermined periodicity ranging from 0.75λ to 3λ of a target wavelength λ. The nanostructures are pillar-shaped nanostructures formed on a surface of the substrate layer, holes formed in the substrate layer, or a combination thereof. At least one nanostructure has a plan-view cross-sectional shape of a circle, an oval, a square, or a rectangle. The plan-view cross-sectional shape of at least one nanostructure includes a rounded corner having a corner radius selected based on a desired light dot nonuniformity of a diffraction pattern generated by the DOE. When the nanostructures are pillar-shaped, a refractive index of the nanostructures is greater than a refractive index of the substrate layer. When the nanostructures are holes, a refractive index of the nanostructures is less than a refractive index of the substrate layer.