Global Shutter Image Sensor Capacitor Layout for Noise Reduction
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Solution Overview
Problem
Existing image sensors face challenges in achieving high shutter efficiency and preventing noise, especially when capturing high-speed images or generating 3D images.
Innovation Solution
The image sensor design includes a semiconductor substrate with transistors on one surface and lower pad electrodes on an interlayer insulating film. A mold insulating layer covers these electrodes, and contact plugs connect them to upper electrodes, enhancing capacitance and reducing noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the image sensor uses a conventional capacitor design, then the device complexity is low, but the shutter efficiency is insufficient and noise occurs during global shutter operations
Solution Approach 1:
The capacitor is divided into multiple segments: a lower pad electrode, multiple lower electrodes arranged in an array, insulating films between them, and an upper electrode. This segmentation increases the total capacitance by creating multiple capacitive elements in series and parallel configurations, thereby improving shutter efficiency without requiring a single large complex capacitor
Solution Approach 2:
The capacitor structure is nested within the pixel circuit layer structure. The lower pad electrode and lower electrodes are formed within the interlayer insulating film layer, and the upper electrode is positioned above them. This nesting allows the capacitor to be integrated into the existing pixel structure without adding significant vertical height or external complexity
2Reliability
If the image sensor uses a conventional electrode design, then the manufacturing process is simple, but noise occurs during global shutter operations
Solution Approach 1:
The lower pad electrode is designed with a specific local quality: it has a main pad portion with a rectangular horizontal cross-section and an extension protruding from the main pad portion. This local structural modification optimizes the electric field distribution and connection characteristics, reducing noise during global shutter operations while maintaining compatibility with existing manufacturing processes
Solution Approach 2:
Multiple lower electrodes are arranged in a two-dimensional array pattern on the lower pad electrode. This dimensional arrangement increases the effective capacitance area without significantly increasing the vertical profile, allowing noise reduction through improved charge storage while maintaining ease of manufacture using standard photolithography and deposition techniques
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 capacitance of the image sensor, leading to improved shutter efficiency and reduced noise during global shutter operations, which is essential for capturing high-quality, distortion-free images.
Implementation Method 1
a photodiode region configured to receive incident light and convert the incident light into an electron-hole pair, therefore generating charges
Data Source
AI summary
Provided is an image sensor including a semiconductor substrate having first and second surfaces, transistors on the first surface, first and second lower pad electrodes apart from each other on a first interlayer insulating film covering the transistors, a mold insulating layer on the first and second lower pad electrodes, a first lower electrode inside a first opening passing through the mold insulating layer on the first lower pad electrode, a second lower electrode inside a second opening passing through the mold insulating layer on the second lower pad electrode, a dielectric film and an upper electrode on the first and second lower electrodes, a first contact plug passing through the mold insulating layer and connected to the first lower pad electrode, and a second contact plug passing through the mold insulating layer and connected to the second lower pad electrode.