Back-Illuminated Image Sensor Light Shielding for Oblique Light
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Solution Overview
Problem
Back-illuminated type solid-state imaging devices face challenges in balancing oblique light characteristics and sensitivity, as high oblique light characteristics can lead to unnecessary light detection, causing image deterioration, while adjusting sensitivity may result in vignetting or color mixture.
Innovation Solution
The implementation of multi-stage light shielding walls between pixels in a matrix arrangement to improve both oblique light characteristics and sensitivity, achieved through a manufacturing method that forms these walls during the pixel array unit formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the height of the light condensing structure is lowered to improve oblique light characteristics, then oblique light characteristics are improved, but sensitivity deteriorates due to vignetting at the opening of the light shielding film
Solution Approach 1:
The light shielding structure is divided into multiple stages with different heights. The first light shielding wall has a first height and the second light shielding wall has a second height higher than the first height. This segmentation allows different portions of the light shielding structure to perform different functions: the lower first stage shields oblique light while the higher second stage prevents vignetting, thus resolving the contradiction between oblique light characteristics and sensitivity
Solution Approach 2:
The invention introduces a vertical dimension variation by creating light shielding walls at different heights (first height and second height). This multi-level vertical structure allows light to be shielded at multiple elevation levels, enabling simultaneous optimization of oblique light rejection and sensitivity by preventing both oblique light entry and vignetting effects
2Illumination intensity
If the width of the light shielding film is increased to improve oblique light characteristics, then oblique light characteristics are improved, but the distance between on-chip lens and light shielding film decreases causing vignetting and sensitivity deterioration
Solution Approach 1:
The light shielding function is segmented into multiple walls at different heights rather than using a single wide film. This allows the light shielding effect to be achieved through vertical segmentation rather than horizontal expansion, maintaining adequate distance between the on-chip lens and light shielding structure while still blocking oblique light
Solution Approach 2:
Instead of increasing the width (horizontal dimension) of the light shielding film, the invention transitions to using multiple light shielding walls at different vertical levels. This dimensional shift from horizontal to vertical light shielding approach achieves the same oblique light blocking function without causing vignetting, thereby maintaining sensitivity
3Reliability
If the focus point is adjusted to the light receiving surface to improve sensitivity, then sensitivity is improved, but color mixture is caused by oblique light from between the on-chip lens and light shielding film
Solution Approach 1:
The light shielding structure is segmented into multiple stages that collectively block oblique light paths from reaching the photodiode. By having light shielding walls at different heights, the structure effectively prevents oblique light from entering between the on-chip lens and light shielding film, thus eliminating color mixture while allowing the focus point to remain at the light receiving surface for optimal sensitivity
Solution Approach 2:
The invention uses vertical multi-level light shielding walls to block oblique light paths that would otherwise cause color mixture. This vertical segmentation creates multiple barriers at different elevations, preventing oblique light from reaching the photodiode even when the focus point is adjusted to the light receiving surface, thereby eliminating color mixture while preserving sensitivity
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 solution effectively enhances oblique light characteristics and sensitivity by minimizing vignetting and color mixture, allowing for better light condensing design and improved process margins.
Implementation Method 1
multi-stage light shielding walls are provided between the pixels
Data Source
AI summary
The present disclosure relates to a solid-state imaging device, a manufacturing method thereof, and an electronic apparatus, in which both oblique light characteristics and sensitivity can be improved. The solid-state imaging device includes pixel array unit in which a plurality of pixels is two-dimensionally arranged in a matrix and multi-stage light shielding walls are provided between the pixels. The present disclosure is applicable to, for example, a back-illuminated type solid-state imaging device and the like.