Image Sensor Pixel Layout With Trench Isolation Against Crosstalk
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Solution Overview
Problem
As CMOS image sensors increase in resolution, pixel size decreases, leading to pixel interference (crosstalk) that reduces image quality and accuracy, which existing technologies fail to adequately address.
Innovation Solution
The design of an image sensing device with a semiconductor substrate, impurity regions, a photoelectric conversion region, switching elements, and insulation structures, where the photoelectric conversion regions are shaped to prevent crosstalk and improve optical characteristics by reducing pixel interference through trench formation and insulation material use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pixel size is decreased to increase resolution, then image resolution is improved, but pixel interference (crosstalk) increases
Solution Approach 1:
The pixel structure is segmented into separate functional regions: a photoelectric conversion region for generating photocharges and an impurity region for storing photocharges. This spatial segmentation allows each region to perform its function independently, reducing interference between adjacent pixels while maintaining high resolution.
Solution Approach 2:
The patent introduces a specialized impurity region with specific electrical properties (different from the surrounding semiconductor substrate) that is optimized for charge storage. This local quality enhancement creates a dedicated storage zone that prevents charge leakage to adjacent pixels, thereby reducing crosstalk while preserving image resolution.
2Measurement precision
If pixel size is decreased to increase resolution, then image resolution is improved, but image quality deteriorates
Solution Approach 1:
By dividing the pixel into distinct photoelectric conversion and storage regions, the patent ensures that photocharge generation and storage occur in spatially separated zones. This prevents charge leakage and signal degradation, maintaining image quality even as pixel dimensions are reduced for higher resolution.
Solution Approach 2:
The impurity region acts as an intermediary between the photoelectric conversion region and the readout circuitry. It temporarily stores photocharges in a controlled environment with appropriate electrical properties, preventing direct interaction that could cause signal degradation or crosstalk, thus preserving image quality.
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 enhances optical characteristics and reduces crosstalk, improving image quality and accuracy by preventing dark defects and enhancing electron movement capabilities.
Implementation Method 1
a photoelectric conversion region disposed over the semiconductor substrate to be directly coupled to the first impurity region and configured to generate photocharges in response to incident light
Data Source
AI summary
An image sensing device is disclosed. The image sensing device includes a semiconductor substrate including an active region, a first impurity region and a second impurity region formed in the active region, a photoelectric conversion region disposed over the semiconductor substrate to be directly coupled to the first impurity region and configured to generate photocharges in response to incident light and transmit the generated photocharges to the first impurity region, a switching element disposed coupled to the first impurity region and the second impurity region and configured to transmit the photocharges stored in the first impurity region to the second impurity region, an insulation structure disposed on sides of the photoelectric conversion region and a plurality of conductive lines disposed in the insulation structure and configured to read out an electrical image signal corresponding to the photocharges generated by the photoelectric conversion region.