Image Sensor Charge Transfer via Opposite-Side Substrate Architecture
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Solution Overview
Problem
Existing image sensors face challenges in reducing noise and improving image quality, while also experiencing process failures and contamination issues during fabrication, particularly when using oxide semiconductor materials in the back-end-of-line (BEOL) process.
Innovation Solution
The development of a highly integrated image sensor design that includes a semiconductor substrate with a photoelectric conversion part, a floating diffusion region, an interlayered insulating layer, a channel pattern, and transfer gate electrodes, which allows for efficient charge transfer and reduced noise, along with a method of fabricating the sensor that forms the channel pattern before the BEOL process to prevent contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the channel pattern is formed using oxide semiconductor material in the BEOL process, then the image sensor achieves high integration and improved image quality, but process failures and contamination issues occur during fabrication
Solution Approach 1:
The channel pattern is formed before the BEOL process using a dedicated semiconductor material layer, preparing the structure in advance to avoid contamination and process failures that would occur if oxide semiconductor material were used during the BEOL process
2Device complexity
If oxide semiconductor material is used in the BEOL process, then device integration is enhanced, but contamination issues arise during fabrication
Solution Approach 1:
The channel pattern is formed in advance before the BEOL process using a dedicated semiconductor material layer, preventing contamination issues that would arise if oxide semiconductor material were introduced during the BEOL process
Solution Approach 2:
The fabrication process is divided into distinct stages: a first semiconductor material layer is formed before the BEOL process for the channel pattern, while the BEOL process uses separate metal layers for interconnections, segregating the oxide semiconductor material from potential contamination sources
3Area of stationary object
If the photoelectric conversion part and transfer gate are disposed on the same surface, then device area is reduced, but noise increases and image quality deteriorates
Solution Approach 1:
The photoelectric conversion part is disposed on the second surface of the substrate while the transfer gate is disposed on the first surface, utilizing the third dimension (vertical separation) to reduce noise and improve image quality without significantly increasing the planar device area
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 enhances image quality by reducing noise and process failures, and prevents contamination issues during fabrication, enabling a more reliable and efficient image sensor production.
Implementation Method 1
a photodiode (PD) that coverts incident light into an electrical signal
Data Source
AI summary
An image sensor and a method of fabricating the same, the image sensor including a semiconductor substrate having a first surface and a second surface facing each other; a first photoelectric conversion part disposed on the second surface of the semiconductor substrate; a first floating diffusion region provided in the semiconductor substrate adjacent to the first surface; a first interlayered insulating layer covering the first surface; a first channel pattern on the first interlayered insulating layer; and a first transfer gate electrode disposed adjacent to the first channel pattern and that controls transfer of charge generated in the first photoelectric conversion part to the first floating diffusion region through the first channel pattern.