Image Sensor Through Electrode Shape for Lower Contact Resistance
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Solution Overview
Problem
Current image sensors face challenges in efficiently integrating photoelectric conversion layers with through electrodes, leading to increased resistance and reduced electrical characteristics due to suboptimal contact areas between electrodes and contact plugs.
Innovation Solution
The image sensor design incorporates a through electrode with a non-planar shape at one end and a planar shape at the other, along with a buffer layer and insulation structure, to enhance contact area and reduce resistance between the through electrode and bottom contact plug, thereby improving electrical connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional through electrode with planar shape is used, then the manufacturing process is simple, but the contact area with bottom contact plug is reduced leading to increased resistance
Solution Approach 1:
The through electrode is designed with an asymmetric non-planar shape where one end has a larger cross-sectional area than the other end. This asymmetric geometry increases the contact area with the bottom contact plug at the larger end, thereby reducing contact resistance and improving electrical characteristics without requiring complex manufacturing processes
Solution Approach 2:
The cross-sectional area parameter of the through electrode is varied along its length, with one end having a larger cross-sectional area than the other. This parameter change optimizes the contact interface with the bottom contact plug, reducing resistance while maintaining manufacturing simplicity
2Reliability
If the contact area between through electrode and bottom contact plug is increased, then resistance is reduced, but the device structure becomes more complex
Solution Approach 1:
The through electrode employs asymmetric geometry where only one end has an enlarged cross-sectional area to increase contact area with the bottom contact plug. This selective asymmetry achieves improved electrical connection without requiring complex structures throughout the entire electrode, balancing performance and simplicity
3Reliability
If a non-planar shape is applied to the through electrode end, then contact area is increased and resistance minimized, but manufacturing precision requirements increase
Solution Approach 1:
The cross-sectional area parameter of the through electrode is gradually varied along its length rather than requiring complex geometric features. This parameter gradient approach achieves increased contact area and reduced resistance while maintaining manufacturability with standard precision tolerances
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 design increases the contact area between the through electrode and the bottom contact plug, minimizing resistance and enhancing the electrical characteristics of the image sensor, leading to improved performance.
Implementation Method 1
The through electrode may electrically connect the photoelectric conversion layer and the floating diffusion region to each other
Implementation Method 2
The photodiode serves to transform an incident light into an electrical signal
Data Source
AI summary
Disclosed is an image sensor including a substrate having a first surface and a second surface opposite to each other, a first photoelectric conversion region and a second photoelectric conversion region in the substrate, a through electrode between the first and second photoelectric conversion regions, an insulation structure on the second surface of the substrate, a first color filter and a second color filter respectively provided on the first and second photoelectric conversion regions, and a photoelectric conversion layer on the insulation structure and electrically connected to the through electrode. The through electrode include a first end adjacent to the first surface and a second end adjacent to the second surface. The first end has a non-planar shape.