Phase Difference Detection Pixels with Exit Pupil Correction
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Solution Overview
Problem
Manufacturing variations such as misalignment in lithography and modularization of imaging devices reduce the accuracy of phase difference detection, which in turn affects the accuracy of auto focus (AF) in imaging apparatus.
Innovation Solution
A solid-state imaging device with phase difference detection pixels that include an on-chip lens and a photoelectric conversion section, where the on-chip lenses and light blocking films are formed with deviations corresponding to the arrangement of phase difference detection pixels, allowing for exit pupil correction based on specific arrangements to maintain AF accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If phase difference detection pixels are formed with standard exit pupil correction, then manufacturing variations cause reduction in AF accuracy, but applying exit pupil correction to all pixels increases device complexity and manufacturing difficulty
Solution Approach 1:
The patent applies exit pupil correction only to specific predetermined phase difference detection pixels rather than uniformly to all pixels. This local differentiation allows the system to maintain high measurement precision in critical areas while avoiding the complexity and manufacturing difficulties that would result from applying correction to every pixel, thus resolving the contradiction between measurement precision and device complexity.
Solution Approach 2:
The patent performs preliminary exit pupil correction during the manufacturing process for predetermined pixels before the device is put into operation. By pre-correcting the optical alignment in specific pixels during fabrication, the system establishes accurate phase difference detection capability in advance, eliminating the need for complex real-time correction mechanisms and reducing overall device complexity.
2Measurement precision
If on-chip lenses and light blocking films are formed with precise alignment, then phase difference detection accuracy is maintained, but manufacturing precision requirements increase production difficulty and cost
Solution Approach 1:
The patent applies high-precision lithography alignment and exit pupil correction only to predetermined phase difference detection pixels rather than to all pixels on the sensor. This localized approach maintains the necessary measurement precision for AF functionality while significantly reducing the overall manufacturing precision requirements and associated production difficulty and cost.
Solution Approach 2:
The patent applies exit pupil correction to only a partial set of pixels (predetermined phase difference detection pixels) rather than to all pixels. This partial action provides sufficient correction to maintain accurate phase difference detection for autofocus purposes while avoiding the excessive manufacturing precision requirements that would result from correcting every pixel, thus balancing measurement precision with manufacturing feasibility.
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 prevents a reduction in AF accuracy even with manufacturing variations, ensuring reliable phase difference detection and auto focus performance.
Implementation Method 1
each phase difference detection pixel includes an on-chip lens and a photoelectric conversion section that is formed on a lower layer than the on-chip lens
Implementation Method 2
The phase difference detection pixel may further include a light blocking film which blocks light from reaching a part of the photoelectric conversion section
Implementation Method 3
a photoelectric conversion section that is formed on a lower layer than the on-chip lens
Data Source
AI summary
There is provided a solid-state imaging device including: a pixel region that includes a plurality of pixels arranged in a two-dimensional matrix pattern. Some of the plurality of pixels are configured to be phase difference detection pixels that include a photoelectric conversion section disposed on a semiconductor substrate and a light blocking film disposed above a portion of the photoelectric conversion section. In particular a location of the light blocking film for the phase difference detection pixels varies according to a location of the phase difference detection pixel. For example, the location of the light blocking film for a phase difference detection pixel positioned at a periphery of the pixel region is different than a location of the light blocking film for a phase difference detection pixel positioned in a center portion of the pixel region.