CMOS Image Sensor Microlens Stack for AF and Pixel Sensitivity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Solid-state imaging devices face sensitivity differences among imaging pixels due to varying microlens shapes and refractive indices, leading to degraded imaging performance and color mixing, especially when in-layer lenses are provided for focus detecting pixels.
Innovation Solution
A solid-state imaging device with a pixel array unit featuring first microlenses formed in the same layer, covered by a film with a refractive index of 1.4 to 2.0, and a second microlens with a higher refractive index formed on focus detecting pixels, acting as an etching stopper and shared between adjacent focus detecting pixels to maintain AF properties and improve sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If in-layer lenses are provided for focus detecting pixels, then autofocus capability is improved, but pixel height increases and sensitivity of imaging pixels degrades
Solution Approach 1:
The patent introduces a vertical stacking architecture where imaging pixels and focus detecting pixels are arranged in different layers (first pixel layer and second pixel layer). This dimensional separation allows in-layer lenses to be provided only for focus detecting pixels without increasing the height of imaging pixels, thereby maintaining sensitivity while enabling autofocus capability.
2Adaptability or versatility
If microlenses with different curvature and refractive index are formed on the same plane, then focus detecting pixel functionality is improved, but pattern discontinuities cause sensitivity differences among imaging pixels
Solution Approach 1:
The patent segments the pixel array into distinct regions: imaging pixels in a first pixel layer and focus detecting pixels in a second pixel layer. This segmentation allows microlenses with different characteristics to be formed for different pixel types without causing pattern discontinuities, as each pixel type has its own dedicated layer with uniform microlens formation.
3Adaptability or versatility
If all pixels are made taller to accommodate in-layer lenses, then focus detecting pixel AF properties are improved, but sensitivity of imaging pixels degrades and color mixing occurs
Solution Approach 1:
The patent utilizes vertical layering to place focus detecting pixels with in-layer lenses in a second pixel layer above the first pixel layer containing imaging pixels. This dimensional arrangement allows the taller structure with in-layer lenses to exist only where needed for autofocus, while imaging pixels maintain their original height and sensitivity 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
The solution enhances the sensitivity of imaging pixels while preserving the autofocus capabilities of focus detecting pixels, preventing height increases and color mixing, thus improving overall image quality.
Implementation Method 1
The film may be formed as an etching stopper film that prevents etching on the first microlenses of the pixels other than the focus detecting pixel when the second microlens is formed
Implementation Method 2
a second microlens formed on the film of a focus detecting pixel among the pixels
Implementation Method 3
a second microlens formed on the film of a focus detecting pixel among the pixels
Data Source
AI summary
The present technology relates to a solid-state imaging device that can improve the sensitivity of imaging pixels while maintaining AF properties of a focus detecting pixel. The present technology also relates to a method of manufacturing the solid-state imaging device, and an electronic apparatus.The solid-state imaging device includes: a pixel array unit including pixels; first microlenses formed in the respective pixels; a film formed to cover the first microlenses of the respective pixels; and a second microlens formed on the film of the focus detecting pixel among the pixels. The present technology can be applied to CMOS image sensors, for example.