Backside Silicon Wafer Design Reducing Infrared Image Artifacts
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Solution Overview
Problem
Modern image devices suffer from image artifacts due to the penetration of infrared (IR) radiation, which is not effectively absorbed by the substrate, leading to inaccuracies in dark pixel calibration and noise correction, especially in thinner wafers where more IR radiation reaches the dark pixels.
Innovation Solution
Applying an antireflective coating and/or absorption layer on the backside of the imager substrate, modifying the backside surface, or altering the spacing between active and dark pixels to redirect or absorb IR radiation, thereby reducing its interaction with dark pixels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the substrate is made thinner to reduce overall device size and cost, then manufacturing cost and device size are reduced, but infrared radiation penetration increases causing more image artifacts in dark pixels
Solution Approach 1:
An infrared absorption layer is introduced as an intermediary between the substrate and the dark pixels. This layer selectively absorbs infrared radiation before it can reach the dark pixels, thereby preventing image artifacts while allowing the substrate to remain thin for cost and size benefits.
Solution Approach 2:
The infrared absorption layer is strategically positioned only where needed - between the substrate and the dark pixels - rather than throughout the entire device. This localized approach addresses the specific problem of infrared penetration to dark pixels without adding unnecessary complexity or cost elsewhere in the device.
2Measurement precision
If dark pixels are used for black level calibration and dark current subtraction, then image processing accuracy is improved, but infrared radiation creates artifacts in these same dark pixels reducing calibration accuracy
Solution Approach 1:
The infrared absorption layer serves as a protective intermediary that shields dark pixels from infrared radiation during calibration operations. This ensures that dark pixel readings reflect only the intended measurement parameters (dark current, black level) without contamination from infrared-induced artifacts, thereby maintaining calibration accuracy.
3Device complexity
If no infrared mitigation is applied to maintain device simplicity, then device complexity is reduced, but image artifacts from infrared radiation increase reducing image quality
Solution Approach 1:
A single infrared absorption layer is introduced as a straightforward intermediary solution. This minimal addition effectively blocks infrared radiation from reaching dark pixels without requiring complex multi-layer structures, active cooling systems, or sophisticated software correction algorithms, thereby maintaining device simplicity while eliminating image artifacts.
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
Significantly reduces image artifacts by minimizing IR radiation contact with dark pixels, improving image quality, especially under extreme light conditions, and allowing the use of thinner substrates without compromising image integrity.
Implementation Method 1
The absorption layer reduces image artifacts from infrared (IR) radiation by absorbing the IR radiation that penetrates into the substrate
Implementation Method 2
applying an antireflective coating and/or absorption layer to the backside of the imager substrate
Data Source
AI summary
Imaging devices having reduced image artifacts are disclosed. The image artifacts in the imaging devices are reduced by redirecting, absorbing or scattering IR radiation that passes through the imaging device substrate away from dark pixels.