Image Sensor Cover Stack With α-Ray Blocking Film
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Solution Overview
Problem
Imaging apparatuses with sealing glass structures suffer from α rays emitted from the glass, which cause white points in captured images, degrading image quality by introducing unwanted light into the image sensor.
Innovation Solution
Incorporating an α-ray transmission preventive film with a thickness of 1 μm or less, having a transmittance of 0.001 count/h or less, between the sensor substrate and the cover substrate, and optionally attaching it to the cover substrate or on-chip lens, along with an antireflection film and a gas or light shielding layers to prevent α ray interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a sealing glass is used to cover the optical element area, then the structural integrity and protection of the imaging apparatus is improved, but α rays are emitted from the glass causing white points in captured images, degrading image quality
Solution Approach 1:
An α-ray transmission preventive film is introduced as an intermediary layer between the sealing glass and the image sensor. This film specifically blocks α rays while allowing visible light to pass through, thereby preventing white points in captured images without compromising the protective function of the sealing glass structure
Solution Approach 2:
The imaging apparatus uses a composite structure combining sealing glass, α-ray transmission preventive film, and antireflection film. Each layer contributes specific properties: the glass provides structural protection, the α-ray film blocks harmful radiation, and the antireflection film optimizes light transmission, together resolving the contradiction between protection and image quality
2Object-affected harmful factors
If an α-ray transmission preventive film is added to block α rays, then image quality is improved by reducing white points, but the device complexity increases
Solution Approach 1:
The patent employs extremely thin films (α-ray transmission preventive film with thickness of 1 μm or less, and antireflection film) that can be integrated into existing imaging apparatus structures. These thin films add minimal complexity while effectively blocking α rays and reducing reflections, maintaining simplicity despite the additional functional layer
Solution Approach 2:
The α-ray transmission preventive film serves multiple functions: it blocks α rays from the sealing glass, allows visible light transmission, and can be combined with antireflection properties. This multi-functionality reduces the need for separate components, thereby limiting the increase in device complexity
3Illumination intensity
If the α-ray transmission preventive film is made thinner to maintain transparency, then light transmission is improved, but the effectiveness in blocking α rays may be reduced
Solution Approach 1:
The patent optimizes the thickness parameter of the α-ray transmission preventive film to be 1 μm or less. This specific thickness parameter achieves the optimal balance between blocking α rays effectively and maintaining high transparency to visible light, allowing the film to fulfill both contradictory requirements simultaneously
Solution Approach 2:
The use of composite material structures (combining α-ray transmission preventive film with antireflection film and sealing glass) allows each layer to be optimized for its specific function. The thin α-ray film focuses on radiation blocking while the composite structure as a whole ensures optimal light transmission, resolving the thickness-transparency effectiveness trade-off
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 solution effectively suppresses the influence of α rays, reducing white points and enhancing image quality by ensuring minimal α ray transmission, while also allowing for miniaturization and reduced flare occurrence in the imaging apparatus.
Implementation Method 1
an α-ray transmission preventive film that transmits image-capturing light... having a transmittance of α rays of 0.001 count/h or less
Implementation Method 2
a sensor substrate having a photoelectric conversion element on which image-capturing light is incident
Implementation Method 3
an antireflection film attached to the α-ray transmission preventive film
Data Source
AI summary
Provided are an imaging apparatus and a manufacturing method for an imaging apparatus that are advantageous for acquiring a captured image in which an influence of a rays is suppressed. An imaging apparatus includes: a sensor substrate having a photoelectric conversion element on which image-capturing light is incident; a cover substrate that covers the photoelectric conversion element and transmits the image-capturing light; and an α-ray transmission preventive film that transmits the image-capturing light.