Imaging Element Anti-Reflection Film for Phase Difference Detection
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Solution Overview
Problem
In imaging technology, light blocking units with high reflection ratios cause scattered light to enter adjacent pixels, leading to color mixing and reduced sensitivity of phase difference detection pixels, especially under low illuminance conditions.
Innovation Solution
A color mixing prevention film with a higher refractive index than the interlayer film is formed on the side walls of the light blocking unit, preventing light from entering adjacent pixels and improving the sensitivity of phase difference detection pixels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a light blocking unit with high reflection ratio is used, then the phase difference detection capability is improved, but scattered light enters adjacent pixels causing color mixing
Solution Approach 1:
An anti-reflection film is introduced as an intermediary layer between the light blocking unit and adjacent pixels. This film mediates the interaction by reducing the reflection of scattered light at the side walls of the light blocking unit, thereby preventing color mixing in adjacent pixels while maintaining the phase difference detection capability of the light blocking unit.
Solution Approach 2:
The optical parameters (reflection ratio, refraction ratio) of the light blocking unit's side walls are modified by coating them with an anti-reflection film. This changes the surface properties to reduce scattered light reflection, thereby eliminating color mixing while preserving the functional optical parameters needed for phase difference detection.
2Measurement precision
If a light blocking unit with high reflection ratio is used, then the phase difference detection capability is improved, but the sensitivity of phase difference detection pixels is reduced
Solution Approach 1:
The anti-reflection film acts as a mediator that reduces light loss from scattered reflections. By minimizing the reflection of incident light at the side walls, more light reaches the phase difference detection pixels, thereby improving sensitivity without compromising the phase difference detection capability provided by the light blocking unit.
3Measurement precision
If a light blocking unit with high reflection ratio is used, then the phase difference detection capability is improved, but under low illuminance conditions the phase difference cannot be detected appropriately
Solution Approach 1:
The scattered light that would normally be harmful (causing color mixing and light loss) is converted into a beneficial effect. The anti-reflection film reduces the harmful reflection, allowing more light to reach the detection pixels. Under low illuminance conditions, this light recovery is crucial for maintaining detection performance.
Solution Approach 2:
The optical parameters of the light blocking unit are modified through anti-reflection coating, changing the reflection and refraction characteristics to maximize light transmission to detection pixels while maintaining the phase difference detection function, especially under low light conditions.
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 suppresses color mixing and enhances the light receiving sensitivity of phase difference detection pixels, ensuring accurate phase difference detection even in low light conditions.
Implementation Method 1
a photo diode configured to generate a pixel signal for each of a plurality of pixels by photoelectric conversion in accordance with a received light intensity
Implementation Method 2
A color mixing prevention film is formed on a side wall of the light blocking unit. The color mixing prevention film can be formed of a material with a refractive index higher than a refractive index of the interlayer film
Data Source
AI summary
The present technology relates to an imaging element, an electronic device, and a manufacturing method that make it possible to prevent color mixing in a pixel adjacent to a phase difference detection pixel and to make the light receiving sensitivity high or more. An anti-reflection film is formed only on the side wall of a light blocking unit that blocks part of the incident light on a photo diode of phase difference detection pixels for detecting the phase difference out of a plurality of pixels. Thereby, the light reflected at the side wall of the light blocking unit does not enter a photo diode of an adjacent pixel, and therefore color mixing is prevented. Furthermore, since the anti-reflection film is not formed on an interlayer layer, the light receiving sensitivity of the light that directly enters the photo diode is not reduced. The present technology can be applied to imaging elements.