Multilayer Nano-Post Lens Array for Wavelength-Separating Image Sensors
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Solution Overview
Problem
Current image sensors face challenges in enhancing the signal-to-noise ratio, particularly in effectively separating and concentrating light by wavelengths, which affects their performance in capturing images across different color spectrums.
Innovation Solution
The image sensor incorporates a color separating lens array with a specific structure, including nano posts and peripheral material layers, etch stop layers, and CMP stop layers, to spatially separate light based on wavelength, concentrating each wavelength on corresponding pixels, thereby improving light concentration efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a color separating lens array is used to separate light by wavelengths, then the signal-to-noise ratio is improved, but the manufacturing complexity increases due to multiple layers and materials
Solution Approach 1:
The color separating lens array is divided into multiple functional layers: a first lens layer with first nano posts for initial light separation, a second lens layer with second nano posts for further separation, and intermediate CMP stop layers and etch stop layers for process control. This segmentation allows each layer to contribute to wavelength separation while maintaining manufacturability through standardized layer structures.
Solution Approach 2:
Different regions of the lens array have different nano post configurations optimized for specific wavelength ranges. The first and second lens layers use different nano post dimensions and materials to handle different portions of the spectrum, allowing each region to be optimized for its specific function while contributing to overall light separation performance.
2Productivity
If multiple nano posts and material layers are used for wavelength separation, then light concentration efficiency is improved, but the manufacturing precision requirements increase
Solution Approach 1:
CMP stop layers are deposited before the nano post formation and patterning steps. These stop layers provide a reference plane and protection layer that enables subsequent nanometer-level patterning processes to achieve high precision. The preliminary deposition of these layers establishes the foundation for precise nano post fabrication in later steps.
Solution Approach 2:
Etch stop layers are introduced as intermediary layers between the CMP stop layers and the nano post structures. These etch stop layers facilitate precise etching processes by providing selective etching planes, allowing the nano posts to be formed with high precision without damaging underlying layers. The intermediary layers act as buffers that enable precise manufacturing.
3Reliability
If a color separating lens array with multiple layers is implemented, then image capture quality is improved, but the device complexity increases
Solution Approach 1:
The color separating lens array structure serves multiple functions: the first and second lens layers perform wavelength separation, the CMP stop layers provide planarization references for subsequent processing, and the etch stop layers enable selective etching. By integrating multiple functions into a single structured array, the design achieves high image capture quality without proportionally increasing overall device complexity.
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
This configuration enhances the image sensor's ability to separate and concentrate light by wavelengths, leading to improved signal-to-noise ratio and image capture quality, particularly in applications like vehicle cameras, security devices, and consumer electronics.
Implementation Method 1
The color separating lens array may spatially separate red light, green light, and blue light by using a spatial contrast of a refractive index, collect the separated light, and transfer the collected light to pixels
Data Source
AI summary
Provided is an image sensor including a sensor substrate, a spacer layer on the sensor substrate, and a color separating lens array on the spacer layer and configured to separate light based on a wavelength of the light, wherein the color separating lens array includes a first lens layer including a plurality of first nano posts and a first peripheral material layer around the plurality of first nano posts, a chemical mechanical polishing (CMP) stop layer on the first peripheral material layer, an etch stop layer on an upper surface of the CMP stop layer and directly on an upper surface of each first nano post of the plurality of first nano posts, and a second lens layer on the etch stop layer, the second lens layer including a plurality of second nano posts and a second peripheral material layer around the plurality of second nano posts.