Pixel Separation Refractive Index Layout for Phase Difference Imaging
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Solution Overview
Problem
Current imaging devices with on-chip lenses struggle to effectively acquire imaging and parallax information due to optical characteristic limitations, particularly in the separation of light between adjacent pixels and photoelectric conversion sections, leading to deteriorated image plane phase difference characteristics.
Innovation Solution
The implementation of an imaging device with inter-pixel separation sections and in-pixel separation sections having different refractive indices, where the inter-pixel separation section has a lower refractive index than the semiconductor substrate and the in-pixel separation section has a refractive index equal to or higher than the substrate, allowing for improved light transmission and reduced total reflection within the pixel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If one on-chip lens is disposed across a plurality of pixels to acquire imaging information and parallax information, then the device complexity is reduced and manufacturing is simplified, but the optical characteristic deteriorates due to light reflection between adjacent photoelectric conversion sections
Solution Approach 1:
The patent applies local quality by differentiating the refractive index characteristics of separation sections based on their location. The inter-pixel separation section uses a first refractive index to prevent light entry from adjacent pixels, while the in-pixel separation section uses a second refractive index (closer to substrate) to minimize reflection and maximize light transmission to photoelectric conversion sections. This localized differentiation resolves the optical characteristic deterioration while maintaining the simplified shared lens structure.
Solution Approach 2:
The patent changes the refractive index parameter of separation sections based on their functional requirements. By adjusting the refractive index of the in-pixel separation section to be closer to the semiconductor substrate refractive index, light transmission is improved and total reflection is reduced. This parameter optimization resolves the contradiction between simplified structure and degraded optical performance.
2Object-affected harmful factors
If an inter-pixel separation section with a low refractive index is provided between adjacent pixels, then light from adjacent pixels is effectively blocked, but light transmission within the pixel to photoelectric conversion sections deteriorates due to total reflection
Solution Approach 1:
The patent segments the light separation function into two distinct components: an inter-pixel separation section for blocking light from adjacent pixels, and an in-pixel separation section for guiding light to photoelectric conversion sections. This segmentation allows each component to be optimized independently - the inter-pixel section uses low refractive index for effective blocking, while the in-pixel section uses refractive index matching for efficient light transmission, resolving the energy loss problem.
Solution Approach 2:
Different refractive index characteristics are assigned to different locations: the inter-pixel separation section has a first refractive index optimized for light blocking, while the in-pixel separation section has a second refractive index (closer to substrate) optimized for light transmission. This local quality differentiation resolves the contradiction between blocking external light and transmitting internal light efficiently.
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 enhances the optical characteristics of the imaging device by improving light transmittance and image plane phase difference performance, enabling better photoelectric conversion and image acquisition.
Implementation Method 1
This allows for light entered in each pixel at a wide angle to be totally reflected between adjacent pixels
Implementation Method 2
an in-pixel separation section provided between the photoelectric conversion sections adjacent to each other inside each of the pixels, electrically separating the adjacent photoelectric conversion sections, and having a second refractive index
Data Source
AI summary
An imaging device according to an embodiment of the present disclosure includes: a semiconductor substrate in which a plurality of pixels is arranged in a matrix, the semiconductor substrate including a plurality of photoelectric conversion sections that each generate electric charge corresponding to a light receiving amount by photoelectric conversion for each of the pixels; an inter-pixel separation section between the pixels adjacent to each other, electrically and optically separating the adjacent pixels from each other, and having a first refractive index; and an in-pixel separation section between the photoelectric conversion sections adjacent to each other inside each of the pixels, electrically separating the adjacent photoelectric conversion sections, and having a second refractive index, a difference between the second refractive index and a refractive index of the semiconductor substrate being smaller than a difference between the first refractive index and the refractive index of the semiconductor substrate.