Distributed Index Lens for High-Efficiency Solid-State Imaging
Here’s PatSnap Eureka !
Summary
Problems
Conventional solid-state imaging devices experience a decrease in light-collecting efficiency at wide incident angles due to the interception of oblique light by Al interconnections, leading to reduced sensitivity, especially in pixels near the edge, making it difficult to apply them in optical systems with short focal lengths and limiting further pixel size reduction.
Innovation solutions
A distributed index lens is developed with a discretized refractive index distribution across an area roughly half the width of the incident light's wavelength, combining light-collecting characteristics of both distributed index and film thickness distribution lenses, allowing for high light-collecting efficiency without the limitations of conventional microlens processing.
TRIZ Analysis
Specific contradictions:
General conflict description:
Principle concept:
If a conventional microlens is used, then light-collecting efficiency is relatively high for incident angles around 20°, but light-collecting efficiency declines suddenly for incident angles more than 20°
Why choose this principle:
The microlens is divided into multiple zones (first zone, second zone, third zone) with different refractive indices. This segmentation allows each zone to handle different incident angle ranges, enabling the lens to maintain high light-collecting efficiency across a wide angular range rather than declining suddenly at 20°.
Principle concept:
If a conventional microlens is used, then light-collecting efficiency is relatively high for incident angles around 20°, but light-collecting efficiency declines suddenly for incident angles more than 20°
Why choose this principle:
Different zones of the microlens are assigned different refractive indices tailored to their specific functional requirements. The first zone (central region) has a higher refractive index for capturing near-normal incident light, while the second and third zones have progressively lower refractive indices for capturing oblique incident light, optimizing performance at each location.
Application Domain
Data Source
AI summary:
A distributed index lens is developed with a discretized refractive index distribution across an area roughly half the width of the incident light's wavelength, combining light-collecting characteristics of both distributed index and film thickness distribution lenses, allowing for high light-collecting efficiency without the limitations of conventional microlens processing.
Abstract
The present invention provides a solid-state imaging apparatus and the like which is able to support an optical system whose incident angle is wide. Each pixel is 2.25 μm square in size, and includes a distributed index lens ( 1 ), a color filter (for example, for green) ( 2 ), an Al interconnections ( 3 ), a signal transmitting unit ( 4 ), a planarized layer ( 5 ), a light-receiving device (Si photodiodes) ( 6 ), and an Si substrate ( 7 ). The two-stage concentric circle structure of the distributed index lens is formed by SiO 2 (n=2) with the film thickness 1.2 μm (“grey color”), the film thickness 0.8 μm (“dots pattern”) and the film thickness of 0 μm (“without pattern: white color”), and the medium surrounding the distributed index lens ( 1 )is air (n=1).