Image Sensor Adhesion via Protruding Pattern and Multilayer Protective Film
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Solution Overview
Problem
The photoconductive layer in direct conversion type image sensors adheres poorly to the CMOS substrate, leading to peeling issues, which affects the efficiency and reliability of X-ray detection.
Innovation Solution
A protruding pattern and protective film with a multilayer structure, including silicon oxide and silicon nitride, are formed on the substrate to increase the contact area between the photoconductive layer and the substrate, using materials like Au, Pt, and CdTe, and incorporating a metal pattern to enhance adhesion and reduce leakage current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a photoconductive layer is deposited on a CMOS substrate by conventional deposition, then the image sensor can be manufactured, but the photoconductive layer adheres poorly to the protective film and may peel from the substrate surface
Solution Approach 1:
A protruding pattern is formed on the substrate before depositing the photoconductive layer. This preliminary structural modification increases the contact area between the photoconductive layer and substrate, improving adhesion strength before the deposition process occurs.
Solution Approach 2:
The protruding pattern creates localized regions of increased surface area at specific contact points. The protective film thickness is varied locally to form protrusions that enhance adhesion only where needed, rather than uniformly across the entire substrate surface.
2Reliability
If a protruding pattern and multilayer protective film structure are formed to increase contact area, then adhesion strength is improved, but the manufacturing process becomes more complex
Solution Approach 1:
The protruding pattern formation is merged with the existing pixel electrode formation process. Both structures are created simultaneously using the same deposition and patterning steps, eliminating the need for separate surface treatment processes and reducing overall manufacturing complexity.
Solution Approach 2:
The protruding pattern serves multiple functions: it increases adhesion area for the photoconductive layer, acts as part of the pixel electrode structure, and can function as an electrical contact structure. This multi-functionality reduces the need for separate components and simplifies the overall device structure.
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
The increased contact area and multilayer structure improve the adhesion strength of the photoconductive layer, enhancing the image sensor's efficiency and process efficiency by eliminating the need for separate surface treatments.
Implementation Method 1
in the direct conversion type, the X-rays are directly converted into electrical signals using a photoconductive layer
Data Source
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AI summary
Disclosed is an improvement of strength of adhesion between a photoconductive layer and a substrate. The image sensor includes a first electrode and a protruding pattern formed around the first electrode on the substrate, a protective film having an protruded surface formed on the protruding pattern, the photoconductive layer formed on the protective film, and a second electrode formed on the photoconductive layer.