Optical Sensor Angle Limiting Filter Gap Control
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Solution Overview
Problem
Optical sensors with angle limiting filters face challenges in maintaining precise angle control due to gap areas on the side walls, leading to light leakage and increased process complexity, especially when miniaturized through semiconductor processes.
Innovation Solution
The optical sensor incorporates an angle limiting filter formed by plugs with a gap space of λ/2 or less between them, allowing for precise incidence angle control and simplifying the process by integrating it with the wiring layer formation, thereby preventing light leakage and reducing the number of necessary processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the angle limiting filter is miniaturized through semiconductor process, then the device size is reduced, but the number of processes is increased when the gap area is to be filled
Solution Approach 1:
The invention extracts the harmful gap area between the angle limiting filter and the substrate, and removes it through selective etching. This eliminates the need for additional filling processes while maintaining the miniaturized device size, thus resolving the contradiction between device size reduction and process complexity increase.
Solution Approach 2:
The invention discards the problematic gap area formed during semiconductor fabrication by selectively removing it through etching processes. This recovery step eliminates the source of light leakage without requiring complex filling operations, thereby maintaining simple manufacturing processes while achieving miniaturization.
2Manufacturing precision
If the gap area is filled to prevent light leakage, then the angle controllability is improved, but the number of processes is increased
Solution Approach 1:
Instead of filling the gap area with additional materials and processes, the invention extracts and removes the gap area through selective etching. This approach achieves the same angle controllability improvement while avoiding the complexity of multiple filling processes.
Solution Approach 2:
The invention replaces the mechanical filling approach with an etching-based removal approach. By substituting the filling process with selective etching of the gap area, the invention achieves precise angle control without increasing process complexity.
3Ease of manufacture
If the gap area is left unfilled, then the manufacturing process is simplified, but light leaks from the gap area causing degradation of angle controllability
Solution Approach 1:
The invention extracts and removes the harmful gap area through selective etching processes. This eliminates light leakage while maintaining manufacturing process simplicity, as the etching steps are integrated into the existing semiconductor fabrication workflow without requiring complex additional filling operations.
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 configuration enables high-precision angle control and simplifies the manufacturing process, ensuring effective light containment and improved performance even with gap areas present, while maintaining the sensor's miniaturized size.
Implementation Method 1
an angle limiting filter that limits an incidence angle of incidence light incident to a light receiving area of the photodiode
Implementation Method 2
between the first plug and the second plug forming the angle limiting filter, a gap area having a space that is equal to or less then λ/2 is disposed
Implementation Method 3
an impurity region, which is formed on a semiconductor substrate, used for a photodiode
Data Source
AI summary
An optical sensor includes an impurity region for a photodiode and an angle limiting filter limiting the incidence angle of incidence light incident to a light receiving area of the photodiode, which are formed on a semiconductor substrate. The angle limiting filter is formed by at least a first plug corresponding to a first insulating layer and a second plug corresponding to a second insulating layer located in an upper layer of the first insulating layer. Between the first plug and the second plug, there is a gap area having a gap space that is equal to or less than λ/2.