Multilayer Imaging Electrode Structure to Block Metal Diffusion
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Solution Overview
Problem
The diffusion of metals from the electrode in stacked imaging devices, such as TiN/Ti structures, leads to abnormal oxidation and deterioration of the photoelectric conversion film and connection issues, affecting the manufacturing process and device performance.
Innovation Solution
The use of a multilayer electrode structure with a first layer containing tantalum nitride and an uppermost layer made of a metal nitride, such as titanium nitride, to suppress metal diffusion and oxidation, enhancing the electrode's stability and connectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a TiN/Ti electrode structure is used, then the electrode can effectively collect charge, but metal diffusion occurs leading to abnormal oxidation and leakage in the photoelectric conversion film
Solution Approach 1:
The electrode is divided into multiple distinct layers with specific functions: the TiN layer serves as the charge collection layer, while the TaN layer acts as a diffusion barrier. This segmentation prevents metal atoms from migrating between layers, eliminating the harmful oxidation effects while maintaining effective charge collection capability.
Solution Approach 2:
The TaN layer functions as an intermediary barrier between the TiN electrode layer and the photoelectric conversion film. This intermediate layer blocks the diffusion path of metal atoms, preventing them from reaching and oxidizing the photoelectric conversion film, thus eliminating the harmful effects without compromising the electrode's primary function.
2Ease of manufacture
If a simple electrode structure is used, then manufacturing is easier, but metal diffusion causes leakage in the photoelectric conversion film
Solution Approach 1:
The electrode structure is segmented into two functional layers (TiN and TaN) that can be deposited using standard sequential sputtering processes. This segmentation approach maintains manufacturing simplicity while effectively preventing metal diffusion, as each layer can be independently optimized and controlled during fabrication.
Solution Approach 2:
The electrode employs a composite structure combining TiN and TaN materials, each contributing specific properties. TiN provides excellent charge collection with appropriate work function, while TaN provides superior diffusion barrier properties. This composite approach maintains manufacturing feasibility through conventional deposition techniques while ensuring photoelectric conversion film integrity.
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 effectively prevents metal diffusion, maintains the integrity of the photoelectric conversion film, and ensures reliable electrode connections, improving the manufacturing process and device performance.
Implementation Method 1
a photoelectric conversion film that converts light to charge
Implementation Method 2
an uppermost layer among the two or more layers contains a metal nitride... suppress metal diffusion
Implementation Method 3
suppress metal diffusion and oxidation... prevents metal diffusion and abnormal oxidation
Data Source
AI summary
An imaging device includes a photoelectric conversion film and an electrode. The photoelectric conversion film converts light to charge. The electrode collects the charge. The electrode includes two or more layers. The two or more layers include a first layer containing tantalum nitride. An uppermost layer among the two or more layers contains a metal nitride.