CMOS Image Sensor Light Reflection Reduction via Grooved Substrate
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
CMOS image sensing devices suffer from image artifacts due to flare effects caused by light reflection from metal films with high light reflectivity, which degrade image quality.
Innovation Solution
The implementation of an image sensing device structure that includes a semiconductor substrate with grooves and a reflection prevention layer to absorb light, minimizing reflection from the metal film by using through-holes in the pad region to direct incident light to a light absorption structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a metal film with high light reflectivity is used in the image sensing device, then electrical connection and signal transmission are improved, but light reflection causes flare effects that degrade image quality
Solution Approach 1:
A reflection prevention layer is introduced as an intermediary between the incident light and the metal film. This layer has a refractive index between air and the metal film, reducing light reflection through refractive index matching. The layer effectively mediates the optical interaction, allowing the metal film to maintain its electrical function while minimizing its harmful reflective effect.
Solution Approach 2:
The high reflectivity of the metal film, which originally causes harmful flare effects, is converted into a beneficial anti-reflective structure. By forming grooves and filling them with reflection prevention material, the structure utilizes the metal film's reflective property in a controlled manner to create an effective anti-reflection mechanism, turning the harmful reflection into a useful optical management feature.
2Object-generated harmful factors
If grooves are formed in the semiconductor substrate to reduce light reflection, then light absorption is improved, but device structure complexity increases
Solution Approach 1:
The reflection prevention layer is segmented into multiple regions: some areas fill the grooves completely while other areas form through-holes that extend through the metal film layer. This segmentation allows different portions of the structure to serve different functions - groove-filled areas maximize light absorption while through-hole areas provide electrical connectivity and additional light management, reducing overall structural complexity.
Solution Approach 2:
The invention merges multiple functions into a single integrated structure. The reflection prevention layer simultaneously serves as: (1) an anti-reflective coating, (2) a structural element defining grooves and through-holes, and (3) an electrical connection pathway when combined with the metal film. This merging reduces the need for separate components and simplifies the overall device architecture.
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 effectively reduces light reflection from the metal film, minimizing flare effects and improving image quality by ensuring most incident light is absorbed rather than reflected, thereby enhancing imaging detection.
Implementation Method 1
the reflection prevention layer configured to reduce reflection of light incident thereon
Implementation Method 2
the light absorption structure is formed to absorb the light received through the at least one through-hole
Implementation Method 3
photosensing pixels that convert light into pixel signals
Data Source
AI summary
An image sensing device capable of minimizing reflection of light incident upon a metal layer is disclosed. The image sensing device includes a semiconductor substrate in which at least one groove is formed, a reflection prevention layer formed over the semiconductor substrate in a manner that the at least one groove is buried by the reflection prevention layer, and a metal layer formed over the reflection prevention layer, and provided with at least one through-hole corresponding to the at least one groove.