Microlens Array Using Dielectric Layers for CMOS Image Sensors
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The manufacturing processes of CMOS image sensors face challenges due to the weak physical properties of organic photoresist, leading to microlens damage and defects during subsequent processes like packaging and bumping, as well as issues with particle absorption affecting image quality.
Innovation Solution
A method involving the formation of a microlens array using a first and second dielectric layer, etched and deposited in a specific power range to prevent damage and create a continuous, gapless shape, utilizing a microlens array mask and etching processes to enhance image sensor manufacturing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If organic photoresist is used to form microlens, then microlens can be formed by patterning and reflowing, but the microlens is easily damaged by physical impact and particles are absorbed causing defects
Solution Approach 1:
The patent changes the material parameter from organic photoresist to inorganic dielectric material (such as silicon oxide or silicon nitride). This material substitution fundamentally alters the physical and chemical properties, providing enhanced mechanical strength, impact resistance, and particle rejection capabilities while maintaining the microlens forming functionality through controlled deposition and reflow processes
Solution Approach 2:
The patent employs a composite structure consisting of multiple dielectric layers (first dielectric layer, second dielectric layer, and third dielectric layer) with different material compositions and functions. Each layer contributes specific properties: the first layer provides structural foundation, the second layer forms the microlens shape through reflow, and the third layer offers protective coverage, collectively achieving both ease of manufacture and high reliability
2Reliability
If inorganic dielectric material is used to form microlens, then microlens strength and particle resistance improve, but manufacturing process complexity increases
Solution Approach 1:
The patent divides the microlens formation process into three distinct functional layers: a first dielectric layer for structural foundation, a second dielectric layer for microlens shape formation through reflow, and a third dielectric layer for protection. This segmentation allows each layer to be optimized independently for its specific function, simplifying the overall manufacturing control despite the multi-layer complexity
Solution Approach 2:
The patent employs a reflow process that serves multiple functions simultaneously: it shapes the second dielectric layer into microlenses, creates smooth optical surfaces, and ensures proper adhesion between layers. This multi-functionality reduces the need for separate processing steps, thereby managing manufacturing complexity while achieving high reliability
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 approach strengthens the microlens array, preventing damage during subsequent processes and improving image quality by forming a continuous, gapless microlens array, thus enhancing the robustness and performance of the image sensor.
Implementation Method 1
forming a seed microlens array by etching the first dielectric layer using the microlens array mask as an etching mask
Implementation Method 2
forming a microlens array by depositing a second dielectric layer over the seed microlens array and in spaces between neighboring seed microlenses
Data Source
AI summary
An image sensor include an interlayer dielectric layer formed over a semiconductor substrate; a color filter array formed over the interlayer dielectric layer; a planarization layer formed over the color filter; and a microlens array having a continuous, gapless shape formed over the planarization layer and spatially corresponding to the color filter array. The microlens array is composed of a first dielectric layer and a second dielectric layer formed over the first dielectric layer.