Image Sensor Color Filter Fabrication with Sacrificial Layer
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Solution Overview
Problem
As the integration density of image sensors increases, the size of each pixel decreases, leading to technical challenges in forming color filters, including deformation and stain failure during the dry etching process.
Innovation Solution
A method of fabricating an image sensor that involves forming a protection layer on the color filter layer to prevent deformation and using a sacrificial layer and protection layer combination to selectively remove the photoresist pattern without deforming the color filters, with the sacrificial layer being water-soluble and the protection layer made of materials like silicon oxide or silicon nitride, allowing for improved process yield and image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the integration density of the image sensor is increased, then the resolution is improved, but the size of each pixel decreases leading to deformation and stain failure in color filters
Solution Approach 1:
A protection layer is formed on the color filter layer before the dry etching process to prevent deformation during fabrication. This preliminary protective action ensures that when etching occurs, the color filter maintains its shape and position, solving the deformation issue that arises from miniaturized pixel dimensions
Solution Approach 2:
A sacrificial layer is introduced as an intermediary between the protection layer and the color filter layer. This sacrificial layer is selectively removed after etching, allowing the protection layer to be separated from the color filter without causing deformation. The intermediary layer acts as a buffer that prevents direct mechanical stress transfer during the removal process
2Manufacturing precision
If a protection layer is formed on the color filter layer to prevent deformation, then manufacturing precision is improved, but process complexity increases
Solution Approach 1:
The sacrificial layer is designed with specific material properties (water-soluble polymer) that allow it to be selectively removed through simple soaking in deionized water. This parameter change in material selection enables easy removal without requiring complex chemical etching or mechanical removal processes, thereby reducing overall process complexity despite adding a layer
3Manufacturing precision
If photoresist pattern is used as etch mask in dry etching process, then manufacturing precision is improved, but residue formation and stain failure occur
Solution Approach 1:
The photoresist pattern is completely removed after serving its purpose as an etch mask. The sacrificial layer is selectively removed first, then the protection layer is separated, and finally the photoresist is completely extracted through ashing or other removal methods. This complete extraction eliminates residue formation that would otherwise cause stain failure in the color filter
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 method enables the formation of image sensors with improved resolution and process yield by preventing color filter deformation and residue formation, thus enhancing image quality and reducing layer thickness on pixel regions.
Implementation Method 1
the selective removing of the first sacrificial pattern may be performed using a deionized water cleaning process
Implementation Method 2
performing a first dry etching process to the first sacrificial layer and the first protection layer to form a first color filter
Data Source
AI summary
A method of fabricating an image sensor is provided. The method may include preparing a substrate with first to third pixel regions, coating a first color filter layer on the substrate, sequentially forming a first sacrificial layer and a first protection layer to cover the first color filter layer, forming a first photoresist pattern on the first protection layer to be overlapped with the first pixel region, performing a first dry etching process using the first photoresist pattern as an etch mask to the first sacrificial layer and the first protection layer to form a first color filter, a first sacrificial pattern, and a first protection pattern sequentially stacked on the first pixel region, and selectively removing the first sacrificial pattern to separate the first protection pattern from the first color filter.