Curved Optical Path Structure for Image Sensor Crosstalk Control
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Solution Overview
Problem
Existing image sensors face challenges in improving light receiving efficiency and reducing crosstalk caused by plain light, particularly when light concentrated by micro lenses does not properly reach the photodiodes.
Innovation Solution
The proposed image sensor design includes a semiconductor substrate with photodiodes, micro lenses to concentrate light, color filters, and an optical path changing member with a curved surface. This optical path changing member is positioned to redirect light that would otherwise be absorbed by pixel isolators, ensuring it reaches the photodiodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If micro lenses are used to concentrate light, then light receiving efficiency should be improved, but light may not properly reach the photodiodes causing reduced efficiency
Solution Approach 1:
The patent introduces an optical path changing member as an intermediary component between the micro lens and the photodiode. This member actively modifies the light path to ensure concentrated light reaches the photodiode, resolving the contradiction between light concentration and accurate light delivery.
Solution Approach 2:
The optical path changing member changes the propagation parameters of light (direction, path) to ensure that concentrated light from the micro lens properly reaches the photodiode, thereby maintaining both high light receiving efficiency and reliable light delivery.
2Object-generated harmful factors
If pixel isolators are used to prevent crosstalk, then signal isolation is improved, but they may absorb useful light reducing light receiving efficiency
Solution Approach 1:
The patent segments the optical path management by using pixel isolators for vertical light blocking and an optical path changing member for horizontal light redirection. This segmentation allows each component to perform its specialized function without compromising overall light receiving efficiency.
Solution Approach 2:
The optical path changing member acts as a mediator that redirects light around the pixel isolators, allowing the isolators to maintain their crosstalk prevention function while the mediator ensures useful light still reaches the photodiode, thus resolving the contradiction between isolation and efficiency.
3Reliability
If an optical path changing member with curved surface is added, then light path control is improved, but device complexity increases
Solution Approach 1:
The patent employs a curved surface (spheroidal or aspherical) for the optical path changing member to achieve effective light path control. The curved geometry naturally redirects light rays without requiring complex mechanical adjustments, thereby improving light path control while keeping the structure relatively simple.
Solution Approach 2:
Instead of adding complex mechanical systems to control light paths in the horizontal plane, the patent utilizes the vertical dimension by placing a curved optical path changing member that passively redirects light through its geometry, thus improving light path control without significantly increasing overall device complexity.
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 design enhances light receiving efficiency by ensuring that concentrated light is effectively directed towards the photodiodes, thereby reducing crosstalk and improving image sensor performance.
Implementation Method 1
micro lenses over the first surface of the semiconductor substrate and configured to concentrate the light
Implementation Method 2
an optical path changing member configured to change a path of at least a portion of the light when the light travels toward the photodiodes through the micro lenses, wherein the optical path changing member has a curved surface being concave or convex on the first surface of the semiconductor substrate
Data Source
AI summary
An image sensor includes a plurality of pixels arranged in a matrix form, photodiodes for the respective pixels, the photodiodes within a semiconductor substrate having a first surface to which light is incident and a second surface that faces away from the first surface, micro lenses over the first surface of the semiconductor substrate and configured to concentrate the light, color filters between the semiconductor substrate and the micro lenses, and an optical path changing member configured to change a path of at least a portion of the light when the light travels toward the photodiodes through the micro lenses. The optical path changing member having a curved surface being concave or convex on the first surface of the semiconductor substrate.