Curved Backside Protrusions for Higher Image Sensor Quantum Efficiency
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Solution Overview
Problem
CMOS image sensors face challenges in maximizing quantum efficiency due to the limited light receiving surface area caused by straight sidewalls of protrusions in absorption enhancement structures, which reduces the absorption of incident electromagnetic radiation.
Innovation Solution
The implementation of an absorption enhancement structure with protrusions having curved sidewalls on the back-side surface of a semiconductor substrate increases the light receiving surface area, enhancing quantum efficiency by redirecting and absorbing more incident radiation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If protrusions with straight sidewalls are used in the absorption enhancement structure, then the manufacturing process is simpler, but the light receiving surface area is reduced and quantum efficiency is limited
Solution Approach 1:
The patent applies curvature to the sidewalls of the protrusions, transforming them from straight to curved geometries. This curvature increases the surface area of the protrusions, thereby enhancing the light receiving area and improving quantum efficiency while maintaining manufacturability through standard semiconductor fabrication processes.
2Area of stationary object
If protrusions with curved sidewalls are implemented, then the light receiving surface area is increased and quantum efficiency is improved, but the manufacturing process becomes more complex
Solution Approach 1:
The curved sidewalls are achieved through controlled etching processes that create the desired geometry. The curvature is designed to be manufacturable using standard semiconductor fabrication techniques, balancing the complexity increase with the benefits of enhanced light absorption and quantum efficiency.
3Reliability
If protrusions with curved sidewalls are used, then photon absorption is enhanced through increased surface area, but the fabrication process requires additional precision
Solution Approach 1:
The curved sidewalls are designed with specific radius values that can be achieved through controlled etching processes. The curvature radius is optimized to maximize light absorption while remaining compatible with standard manufacturing precision capabilities, ensuring reliable photon absorption enhancement without requiring excessive fabrication precision.
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 curved sidewall design increases the light receiving surface area, thereby enhancing the quantum efficiency of the image sensor, improving its ability to convert optical images into digital data effectively.
Implementation Method 1
increasing the light receiving surface area and enhancing photon absorption through the use of an absorption enhancement structure
Data Source
AI summary
Various embodiments of the present disclosure are directed towards a method for forming an integrated chip. The method includes forming a mask layer on a first side of a semiconductor substrate. The mask layer comprises a plurality of sidewalls defining a plurality of openings. A first etch process is performed on the semiconductor substrate to form a plurality of recesses within the semiconductor substrate. A second etch process is performed on the semiconductor substrate to expand the plurality of recesses and form a plurality of protrusions that comprise curved opposing sidewalls.