Color Filter Patterning Using Hard Mask Layers
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Solution Overview
Problem
Scaling down color filters in image sensors is challenging due to specific processing features, which can lead to sacrifices in light transmission, process controllability, yield, and optical performance when introducing new materials.
Innovation Solution
The use of optically transparent hard mask layers, such as oxide layers, for color filter patterning allows the extension of existing low-cost, mature color filter materials to smaller pixel sizes, limited only by patterning resolution, which is smaller than the shortest visible wavelength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If color filters are scaled down to follow pixel size reduction, then image sensor resolution is improved, but light transmission and optical performance deteriorate
Solution Approach 1:
The patent introduces a hard mask layer as an intermediary component between the color filter and the pixel structure. This hard mask layer enables precise patterning of color filters at scaled dimensions while maintaining their optical properties, as it provides a robust etching mask that allows accurate pattern transfer without compromising the underlying color filter material's light transmission characteristics
Solution Approach 2:
The patent changes the material parameter of the etching mask from traditional photoresist to hard mask materials such as oxide layers. This parameter change enables better pattern fidelity and etching control at scaled dimensions, allowing color filters to be miniaturized while preserving their optical transmission properties through precise pattern formation
2Manufacturing precision
If new materials are introduced to improve color filter scaling, then manufacturing precision is improved, but process complexity and cost increase
Solution Approach 1:
The hard mask layer serves multiple functions: it acts as an etching mask for pattern transfer, provides structural support during processing, and enables precise alignment for color filter patterning. This multi-functionality eliminates the need for additional specialized materials or processes, maintaining process simplicity while achieving high manufacturing precision
Solution Approach 2:
The patent uses the hard mask layer as a template or copy that defines the final color filter pattern. The hard mask is patterned first with high precision, then this pattern is copied onto the color filter layer through etching, ensuring manufacturing precision without requiring direct patterning of the color filter material itself
3Productivity
If color filter size is reduced, then pixel density is improved, but yield and process controllability deteriorate
Solution Approach 1:
The hard mask layer is formed and patterned before the color filter material is deposited or processed. This preliminary action establishes a precise pattern template that guides subsequent color filter formation, ensuring that even at reduced sizes, the color filters are formed with high accuracy and consistency, thereby maintaining high yield
Data Source
AI summary
Embodiments are disclosed of an apparatus comprising a color filter arrangement including a set of color filters. The set of color filters includes a pair of first color filters, each having first and second hard mask layers formed thereon, a second color filter having the first hard mask layer formed thereon, and a third color filter having no hard mask layer formed thereon. Other embodiments are disclosed and claimed.