CMOS Image Sensor Pixel Layout for Uniform Same-Color Sensitivity
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Solution Overview
Problem
Solid-state image-capturing elements with Bayer-arrayed pixel groups, particularly those in 4×4 arrays, experience inter-pixel sensitivity differences, leading to non-uniform sensitivity characteristics.
Innovation Solution
Incorporating an on-chip lens for each m×m array of pixels within an n×n same-color pixel group, along with a sensitivity adjustment structure featuring intra-pixel grooves shallower than the element separating portion on the semiconductor substrate, to enhance light incidence and scattering, thereby uniformizing sensitivity across pixels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pixels are arranged in an n×n same-color pixel group, then the pixel array can capture color images with improved resolution, but inter-pixel sensitivity differences are generated leading to non-uniform sensitivity characteristics
Solution Approach 1:
The patent applies local quality by providing sensitivity adjustment structures (dug portions) at specific predetermined pixels within the same-color pixel group rather than uniformly across all pixels. This localized modification allows targeted correction of sensitivity variations at specific positions while maintaining the overall n×n array structure and its color capture capabilities.
Solution Approach 2:
The patent changes the physical parameter of the semiconductor substrate by creating dug portions with different depths at predetermined pixels. These depth variations modify the light path length and sensitivity characteristics locally, enabling adjustment of sensitivity uniformity across the pixel group without changing the overall array configuration.
2Use of energy by moving object
If an on-chip lens is arranged for each m×m array of pixels, then light collection efficiency is improved, but sensitivity uniformity across pixels deteriorates
Solution Approach 1:
The patent combines the on-chip lens arrangement (providing localized light collection for each m×m sub-array) with localized sensitivity adjustment structures at predetermined pixels. This allows each pixel to benefit from its group's on-chip lens while receiving additional individualized sensitivity correction through the dug portions, addressing both light collection efficiency and sensitivity uniformity.
Solution Approach 2:
The sensitivity adjustment structures are designed to preemptively counteract the sensitivity variations that arise from the on-chip lens arrangement. By pre-positioning dug portions at predetermined pixels where sensitivity differences are expected, the system compensates for these variations before they affect 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
The solution effectively reduces inter-pixel sensitivity differences, resulting in more uniform sensitivity characteristics and improved image capture performance by optimizing light path lengths and scattering within the pixel groups.
Implementation Method 1
a sensitivity adjustment structure with a configuration in which a dug portion shallower than an element separating portion for separating a photoelectric converting section in units of the pixels is provided on a light-incidence surface side of a semiconductor substrate at a predetermined pixel in the same-color pixel group
Implementation Method 2
an on-chip lens provided for each m×m array (m is an integer which is equal to or smaller than n) of pixels in the same-color pixel group
Implementation Method 3
an element separating portion for separating a photoelectric converting section in units of the pixels
Data Source
AI summary
The present disclosure relates to a solid-state image-capturing element and electronic equipment that make it possible to attain more uniform sensitivity characteristics.The solid-state image-capturing element is configured such that it is provided with an on-chip lens for each 2×2 array of pixels in a same-color pixel group including pixels that receive light of the same color and that are arranged in a 4×4 array. Further, a sensitivity adjustment structure is configured by providing, on the light-incidence-surface side of a semiconductor substrate of predetermined pixels in the same-color pixel group, intra-pixel grooves with various shapes that are formed by digging shallower than an element separating portion for separating a photoelectric converting section in units of the pixels. For example, the present technology can be applied to a CMOS image sensor.