Optical Device Light-Shielding Layers for Fingerprint Recognition
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Solution Overview
Problem
Traditional optical devices for fingerprint recognition suffer from light leakage through transparent material layers, causing cross-talk interference between neighboring pixel regions due to refraction or diffraction, which existing multi-layered light-shielding designs fail to adequately address.
Innovation Solution
An optical device with a substrate, dielectric layer, patterned light-transmitting layer, and continuous light-shielding layers on both sides of the patterned light-transmitting layer, where the light-shielding layers are conformally formed using materials like titanium nitride or tungsten, and the patterned light-transmitting layer has a high transparency and specific thickness-to-width ratios to prevent light leakage and maintain collimation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If multi-layered light-shielding layers are stacked on both sides of the collimator, then light leakage is reduced, but light still leaks through transparent material layers causing cross-talk interference
Solution Approach 1:
The patent employs a composite light-shielding structure combining transparent material layers with light-shielding material layers. The transparent material (e.g., silicon oxide, silicon nitride) provides structural integrity and adhesion, while the light-shielding material (e.g., aluminum, chromium, titanium nitride) blocks light transmission. This composite approach prevents light leakage through the collimator edges while maintaining structural stability, effectively eliminating cross-talk interference between adjacent pixel units.
Solution Approach 2:
The light-shielding material layers are strategically positioned only at critical locations where light leakage occurs - specifically on the incident light side and exit light side of the collimator, and at the edges of the light-transmitting layer. This localized application ensures light blocking where needed while minimizing overall structure complexity and material usage.
2Stability of the object's composition
If the light-transmitting layer thickness is increased to improve collimation, then collimation effect is enhanced, but light intensity reaching pixel units decreases
Solution Approach 1:
The patent optimizes the thickness of the light-transmitting layer within a specific range (5-15 micrometers) to achieve the desired collimation effect while maintaining sufficient light transmission. Additionally, the light-shielding material layer thickness is controlled at 300-1500 Å to provide effective light blocking without excessive absorption of useful light. These parameter optimizations balance collimation performance with light intensity requirements.
3Reliability
If continuous light-shielding layers are formed on both sides of the patterned light-transmitting layer, then cross-talk is reduced, but manufacturing complexity increases
Solution Approach 1:
The light-shielding structure is segmented into distinct functional layers: transparent material layers providing structural support and light-shielding material layers providing optical blocking. This segmentation allows each layer to be optimized independently and simplifies the manufacturing process by enabling sequential deposition and independent pattern alignment.
Solution Approach 2:
The transparent material layers serve multiple functions: providing structural support, ensuring adhesion between layers, and acting as part of the light-shielding system when combined with the light-shielding material layers. This multi-functionality reduces the need for additional separate components, simplifying the overall device structure.
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 continuous light-shielding layers effectively prevent light leakage, concentrating incident light onto pixel units and reducing cross-talk, while the specific size ratios ensure appropriate light intensity and collimation, enhancing the light receiving capability of the optical device.
Implementation Method 1
light entering the collimator to leak from the transparent material layers on both sides of the collimator into neighboring pixel regions by means of refraction or diffraction
Implementation Method 2
light entering the collimator to leak from the transparent material layers on both sides of the collimator into neighboring pixel regions by means of refraction or diffraction
Implementation Method 3
the light-shielding layer is formed by stacking black light-shielding material layers and transparent material layers on top of each other
Implementation Method 4
an optical device having an optimal collimation effect and capable of avoiding cross-talk
Data Source
AI summary
An optical device is provided. The optical device includes a substrate including a plurality of pixel units, a dielectric layer disposed on the substrate, a patterned light-transmitting layer disposed on the dielectric layer and corresponding to the plurality of pixel units, and a plurality of continuous light-shielding layers disposed on the dielectric layer and located on both sides of the patterned light-transmitting layer. A method for fabricating an optical device is also provided.