RGB Stacked NIR Filter Layout for Compact Solid-State Imaging
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Solution Overview
Problem
Existing solid-state imaging devices are hindered by the use of glass substrates with mounted filters, leading to increased size, cost, and reduced light sensitivity due to the interposition of these substrates, making it difficult to downsize the devices and maintain sensitivity.
Innovation Solution
A compact and cost-effective solid-state imaging device is achieved by using a substrate with RGB stacked filters directly on photodiodes, eliminating the need for a glass substrate with visible light cut filters, and improving light sensitivity by stacking red, green, and blue filters on the photodiode for near-infrared light to effectively remove visible light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a glass substrate with mounted filters is used, then light filtering function is achieved, but device size increases and manufacturing cost increases
Solution Approach 1:
The patent merges the substrate and filter into a single integrated component. The filter is formed directly on the substrate through deposition processes, eliminating the need for a separate glass substrate with mounted filters. This integration reduces device size while maintaining the light filtering function, as the filter layer becomes part of the substrate structure itself.
Solution Approach 2:
The patent extracts the glass substrate from the system by forming filters directly on the main substrate. The separate glass substrate that previously held the filters is removed entirely, and the filtering function is achieved through thin film deposition directly on the substrate surface, thereby reducing overall device volume.
2Reliability
If a glass substrate with mounted filters is used, then light filtering function is achieved, but manufacturing cost increases
Solution Approach 1:
The patent combines multiple manufacturing steps into a single integrated process. The filter is deposited directly on the substrate in the same manufacturing line, eliminating separate steps for mounting filters on glass substrates. This integration reduces manufacturing complexity and cost while maintaining effective light filtering.
Solution Approach 2:
The patent replaces expensive glass substrates with cheaper substrate materials that can be processed more economically. The filter function is achieved through thin film deposition rather than requiring costly glass substrates with precision-mounted filters, thereby reducing manufacturing cost.
3Strength
If a glass substrate is interposed above photodiodes, then structural support is provided, but light receiving sensitivity is lowered
Solution Approach 1:
The patent removes the glass substrate from between the light source and photodiodes. By forming filters directly on the substrate, the optical path is cleared of unnecessary intermediate layers, allowing light to reach the photodiodes without passing through the glass substrate, thereby improving light receiving sensitivity while the substrate itself provides the necessary structural support.
4Reliability
If RGB stacked filters are stacked on photodiode for near infrared light, then visible light is removed, but device complexity increases
Solution Approach 1:
The patent merges multiple filter functions into a single stacked filter structure formed on the substrate. The RGB filters are deposited in layers directly on the substrate in an integrated manufacturing process, eliminating the need for separate filter components and their assembly. This reduces device complexity while achieving effective visible light removal through the combined filtering action of the stacked layers.
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 allows for a downsized, low-cost, and highly sensitive imaging device that improves light sensitivity and resistance to impacts by eliminating the need for a glass substrate and optimizing filter placement, while maintaining effective removal of visible light and transmission of near-infrared light.
Implementation Method 1
a first red filter configured to transmit red light and the near infrared light and remove light in a wavelength band other than the red light and the near infrared light, a first green filter configured to transmit green light and the near infrared light and remove light in a wavelength band other than the green light and the near infrared light, and a first blue filter configured to transmit blue light and the near infrared light and remove light in a wavelength band other than the blue light and the near infrared light
Data Source
AI summary
A solid-state imaging device includes a substrate having a major surface, a photodiode for near infrared light disposed on the major surface and configured to detect near infrared light, and a stacked filter disposed on the photodiode for near infrared light and configured to remove visible light. The stacked filter includes a red filter configured to transmit red light and the near infrared light and remove light other than the red light and the near infrared light, a green filter configured to transmit green light and the near infrared light and remove light other than the green light and the near infrared light, and a blue filter configured to transmit blue light and the near infrared light and remove light other than the blue light and the near infrared light. The red filter, the green filter, and the blue filter are stacked above the photodiode for near infrared light.