Image Sensor Micro-Lens Array LTO Layer Delamination Prevention
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The manufacturing of image sensors faces challenges such as delamination of capping layers due to stress differences and the attachment of polymer particles to micro-lens arrays, which reduces sensitivity and yield rate, particularly in CMOS image sensors during wafer back grinding and packaging processes.
Innovation Solution
The implementation of a Low Temperature Oxide (LTO) layer on the micro-lens array, combined with a thermo-setting resin layer and passivation layers, to prevent delamination and particle attachment, while ensuring a zero gap between adjacent lenses for enhanced sensitivity and yield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a capping layer is used in CMOS image sensor manufacturing, then the structural integrity is improved, but delamination occurs due to stress difference between layers
Solution Approach 1:
A stress compensation layer is introduced between the capping layer and the substrate to act as a mediator that absorbs and balances the stress difference between layers, preventing delamination while maintaining structural integrity
2Ease of manufacture
If photoresist layer is used in manufacturing processes, then the fabrication capability is improved, but polymer particles are generated and attach to micro-lens array
Solution Approach 1:
The harmful polymer particles are extracted and removed from the system by applying oxygen plasma treatment to the micro-lens array, eliminating particle contamination while preserving the fabrication benefits of photoresist usage
3Measurement precision
If micro-lens array is cleaned to remove particles, then the sensitivity is improved, but the cleaning difficulty reduces yield rate
Solution Approach 1:
Oxygen plasma treatment is applied in advance to the micro-lens array to prevent polymer particle attachment before they can contaminate the surface, eliminating the need for difficult cleaning operations and maintaining high yield rate
4Measurement precision
If zero gap between lenses is achieved, then the light conversion sensitivity is improved, but the manufacturing precision requirement increases
Solution Approach 1:
The physical and chemical parameters of the lens material are optimized, including refractive index, curing characteristics, and shrinkage properties, to enable self-alignment and automatic gap closure during the curing process, achieving zero gap without requiring extreme manufacturing precision
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 improves the sensitivity and yield rate of image sensors by preventing delamination and particle attachment, maintaining lens array integrity and optimizing light conversion efficiency.
Implementation Method 1
delamination of a capping layer may occur in a pad open section, the pad of which serves for signal connection with exterior signal lines, due to a stress difference between layers of and/or over the pad
Implementation Method 2
in a wafer back grinding process, a packaging process and the like, polymer particles derived from the photoresist layer and the like may be generated and may attach to the micro-lens array
Implementation Method 3
An image sensor is a semiconductor device that converts an optical image into electrical signals. Such an image sensor includes a micro-lens array that guides incident light toward a photodiode
Data Source
AI summary
Disclosed is an image sensor. The image sensor includes a lower structure having a photodiode and an interconnection, a passivation layer on the lower structure, a thermo-setting resin layer on the passivation layer, a color filter array on the thermo-setting resin layer, a micro-lens array on the color filter array, and a Low Temperature Oxide (LTO) layer on the micro-lens array.