CMOS Image Sensor Nanopillars for Small-Pixel Photosensitivity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional CMOS image sensors have lower photosensitivity due to a small absorption coefficient for visible light and limited light receiving area, which is exacerbated by the reduction in cell size for high integration, leading to reduced light receiving capability.
Innovation Solution
The formation of nanopillars on the light receiving elements, made of crystalline silicon, which increase the absorption coefficient for visible light and extend the light receiving area into three-dimensional space, overcoming the limitations of two-dimensional structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the cell size is reduced for high integration, then the integration density is improved, but the light receiving area is reduced
Solution Approach 1:
The patent transitions from a two-dimensional flat light receiving surface to a three-dimensional nanopillar structure. By forming nanopillars that extend vertically from the substrate surface, the light receiving area is increased in the vertical dimension while maintaining a compact footprint, thereby resolving the contradiction between high integration density and sufficient light receiving area.
2Device complexity
If conventional flat light receiving elements are used, then the device structure is simple, but the absorption coefficient for visible light is small
Solution Approach 1:
The patent employs curved nanopillar structures instead of flat surfaces. The curved surfaces of the nanopillars enhance light trapping and absorption by increasing the optical path length and reducing reflection, thereby improving photosensitivity while maintaining relative structural simplicity through standard semiconductor fabrication processes.
3Ease of manufacture
If the light receiving elements are exposed as flat surfaces, then the manufacturing process is simple, but the light receiving capability is limited
Solution Approach 1:
The patent divides the continuous flat light receiving surface into discrete nanopillar segments. This segmentation increases the effective surface area for light absorption while still using standard photolithography and etching processes, thus maintaining manufacturing simplicity while dramatically improving light receiving capability.
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 nanopillar structure enhances light absorption and re-absorption, significantly increasing photosensitivity and maintaining or exceeding light receiving area despite reduced cell size, while allowing for high integration and low power consumption.
Implementation Method 1
nanopillar structure enhances light absorption and re-absorption, significantly increasing photosensitivity
Implementation Method 2
a CMOS image sensor having a great photosensitivity... light detecting part for detecting light
Data Source
AI summary
Provided are a CMOS image sensor and a method for fabricating the same. A nanopillar is plurally formed at an upper end of a light receiving element.