Aerogel-Encapsulated Image Sensor Reducing Light Reflection
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Solution Overview
Problem
Conventional image sensor encapsulation methods, such as those using glass packaging layers, suffer from significant light reflection and reduced light transmission due to the refractive index mismatch between the packaging material and the ambient medium, which affects the performance of CMOS image sensors by reducing the amount of light reaching the pixel array.
Innovation Solution
The use of an aerogel layer with a low refractive index, typically between 1.0 and 1.35, encapsulates the image sensor pixel array, formed through methods like spin-coating, dip-coating, or spray-coating, and cured using techniques such as super-critical drying or pinhole drying, to minimize light reflection and maximize light transmission while providing protection from contaminants.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a glass packaging layer is used to encapsulate the image sensor, then protection from contaminants is improved, but light transmission is reduced due to refractive index mismatch
Solution Approach 1:
The patent changes the refractive index parameter of the encapsulation material from conventional glass (n≈1.5) to aerogel (n≈1.0-1.35), which is closer to the refractive index of air and the microlens material. This parameter change reduces optical reflection at interfaces and improves light transmission while maintaining protective encapsulation functionality.
Solution Approach 2:
The patent uses aerogel, a composite material with unique properties combining low density, high porosity, and low refractive index. This composite material simultaneously provides mechanical protection against contaminants and optimal optical transmission, resolving the contradiction between protection and light transmission.
2Strength
If conventional encapsulation materials are used, then structural protection is improved, but optical performance deteriorates due to light reflection
Solution Approach 1:
The patent changes the refractive index parameter of the encapsulation material from conventional glass (n≈1.5) to aerogel (n≈1.0-1.35), which is closer to the refractive index of air and the microlens material. This parameter change reduces optical reflection at interfaces and improves light transmission while maintaining protective encapsulation functionality.
Solution Approach 2:
The patent employs aerogel, a porous material with extremely low density and high porosity (up to 99%). The porous structure contributes to the low refractive index while maintaining mechanical integrity, thereby reducing light reflection losses and improving optical efficiency.
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 aerogel-encapsulated image sensor enhances light transmission by reducing reflections and maintaining high light transmission efficiency, while also protecting the microlens array from contaminants, thereby improving the overall performance and reliability of the image sensor.
Implementation Method 1
The aerogel layer that encapsulates the pixel array of the image sensor. The aerogel layer may have a refractive index, n, that satisfies 1.0≦n≦1.35 at visible wavelengths
Implementation Method 2
The step of curing may include at least one of (a) super-critical drying, (b) surface-modification drying, and (c) pinhole drying an uncured aerogel portion
Implementation Method 3
The step of curing may include at least one of (a) super-critical drying, (b) surface-modification drying, and (c) pinhole drying an uncured aerogel portion
Data Source
AI summary
An aerogel-encapsulated image sensor includes a device die with an image sensor fabricated thereon and an aerogel layer that encapsulates the image sensor. A method for encapsulating image sensor pixel arrays of respective bare image sensors formed on a sensor array sheet may include injecting an uncured aerogel portion on each image sensor pixel array, and curing each uncured aerogel portion. The step of curing may include at least one of (a) super-critical drying, (b) surface-modification drying, and (c) pinhole drying an uncured aerogel portion. The method may further include singulating the sensor array sheet into a plurality of aerogel-encapsulated image sensors. A method for encapsulating image sensor pixel arrays of respective bare image sensors on a device wafer may include forming an aerogel layer on each bare image sensor. The step of forming may include at least one of spin-coating, dip-coating, and spray-coating the aerogel layer.