Image Pickup Device Step Part Light Shielding Autofocus
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Solution Overview
Problem
Existing image pickup devices with focus detection functions face challenges in achieving both pixel characteristics for image pickup and autofocus characteristics with a simple structure, particularly in backside irradiation type image pickup apparatuses, where the light condensing position on the silicon substrate side limits autofocus performance due to increased cost and manufacturing complexity.
Innovation Solution
The implementation of an image pickup device with adjacent first and second pixels, each having a photodetection section and a light condensing section with a step part on the photodetection surface, where at least the wall surface of the step part is covered with a light shielding section, and both pixels share the same lens shape and material for the light condensing section, with an organic film filling the step part and a fixed charge film between the photodetection and light condensing sections, and a wiring layer serving as a light shielding section.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the light condensing position is located on the silicon substrate side to suppress color mixing, then color mixing is reduced, but sufficient autofocus characteristics cannot be obtained
Solution Approach 1:
The patent introduces a step part that creates a height difference (vertical dimension) between image pickup pixels and image plane phase difference pixels. This dimensional change allows the light condensing positions to be at different depths, enabling both color mixing suppression and adequate autofocus characteristics to coexist by separating the optical paths in the vertical dimension.
Solution Approach 2:
The patent segments the pixel array into two distinct types: image pickup pixels with photodetection sections at a first depth and image plane phase difference pixels with photodetection sections at a second depth. This segmentation allows each pixel type to have optimized light condensing characteristics suitable for its specific function, resolving the contradiction between color mixing suppression and autofocus performance.
2Reliability
If the shape of the on-chip lens is changed for each of the image pickup pixel and the focus detection pixel, then pixel characteristics and autofocus characteristics can be optimized, but cost and the number of manufacturing steps increase
Solution Approach 1:
The patent employs a universal on-chip lens design where the same lens shape and material are used for both image pickup pixels and image plane phase difference pixels. The differentiation between pixel types is achieved not through lens variation but through the step part structure that creates depth separation, thereby maintaining manufacturing simplicity while achieving distinct functional characteristics.
Solution Approach 2:
The patent applies local quality differentiation through the step part structure rather than through lens design. The vertical position (local quality in the depth dimension) is varied between pixel types to achieve different optical characteristics, while the lens itself remains uniform, thus avoiding increased manufacturing complexity.
3Object-affected harmful factors
If a member on the photodetection side is formed with small thickness to suppress color mixing, then color mixing is suppressed, but the light condensing position is located on the silicon substrate side limiting autofocus performance
Solution Approach 1:
The patent resolves this contradiction by utilizing the vertical dimension through the step part structure. Instead of increasing horizontal structural complexity, the solution creates a vertical separation between pixel types, allowing thin film structures to suppress color mixing while the depth-differentiated photodetection sections maintain adequate autofocus characteristics.
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 allows for effective light condensation at suitable positions for both image pickup and phase difference pixels, reducing oblique incident light crosstalk and maintaining high pixel characteristics while improving autofocus performance with a simplified structure.
Implementation Method 1
the light condensing section condensing incident light toward the photodetection section
Implementation Method 2
the light condensing section condensing incident light toward the photodetection section
Implementation Method 3
the photodetection section including a photoelectric conversion element
Data Source
AI summary
An image pickup device according to the present disclosure includes a first pixel and a second pixel each including a photodetection section and a light condensing section, the photodetection section including a photoelectric conversion element, the light condensing section condensing incident light toward the photodetection section, the first pixel and the second pixel being adjacent to each other and each having a step part on a photodetection surface of the photodetection section, in which at least a part of a wall surface of the step part is covered with a first light shielding section.