Back-Illuminated Light Sensor Masking for Stray Light Blocking
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Solution Overview
Problem
Back-illuminated light detection devices face degradation in detection accuracy due to stray light incident from the side surface of the light receiving element, and existing light shielding underfills are insufficient in preventing this issue.
Innovation Solution
A light detection device configuration that includes a back-illuminated light receiving element, a circuit element, a connection member, an underfill, and a frame-shaped light shielding mask with a light shielding layer, where the underfill reaches a gap between the light receiving element and the light shielding layer, and the frame's opening is narrowed from the first opening edge towards the second, allowing the underfill to stabilize and increase the light shielding mask's strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the underfill reaches the side surface of the light receiving element to reliably bond the light receiving element and the circuit element, then the bonding reliability is improved, but stray light is incident from the side surface to the light receiving portion degrading detection accuracy
Solution Approach 1:
The light shielding structure is divided into multiple light shielding portions arranged in an array, each corresponding to a light receiving portion. This segmentation allows the underfill to reach the side surface for bonding while the light shielding portions block stray light from entering the light receiving portions, thus resolving the contradiction between bonding reliability and detection accuracy
Solution Approach 2:
Light shielding portions are introduced as intermediary elements between the underfill and the light receiving portions. These light shielding portions act as mediators that allow the underfill to perform its bonding function while preventing stray light from degrading detection accuracy, thus resolving the technical contradiction
2Measurement precision
If a resin containing filler having light shielding property is used as underfill to prevent stray light, then detection accuracy is improved, but light cannot be sufficiently shielded in accordance with wavelength
Solution Approach 1:
Instead of relying on the optical properties of the underfill material itself, the invention changes the approach by introducing discrete light shielding portions with specific geometric parameters (size, shape, arrangement) that provide reliable light shielding across different wavelengths, thus resolving the contradiction between detection accuracy and light shielding effectiveness
3Measurement precision
If a light shielding mask is provided to prevent stray light from incident to the light receiving element, then detection accuracy is improved, but the light shielding mask requires additional components increasing device complexity
Solution Approach 1:
The light shielding portions are merged with the underfill structure, forming an integrated component rather than a separate mask. This merging reduces device complexity by eliminating additional components while maintaining the light shielding function that improves detection accuracy, thus resolving the technical contradiction
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 effectively prevents stray light from degrading detection accuracy, provides stable fixing strength, and protects the light receiving element from external forces and moisture, while maintaining mechanical strength and uniformity among light receiving portions.
Implementation Method 1
a light shielding layer formed on an inner surface of the opening... the light shielding mask includes a frame having an opening in which the light receiving element is located and a light shielding layer formed on an inner surface of the opening
Data Source
AI summary
A light detection device includes: a back-illuminated light receiving element; a circuit element; a connection member; an underfill; and a light shielding mask. The light shielding mask includes a frame having an opening and a light shielding layer formed on an inner surface of the opening. A first opening edge on the side of the circuit element in the opening is located at the outside of an outer edge of the light receiving element. A second opening edge opposite to the circuit element in the opening is located at the inside of the outer edge of the light receiving element. The opening is narrowed from the first opening edge toward the second opening edge. A width of the frame increases from the first opening edge toward the second opening edge. The underfill reaches a gap between the light receiving element and the light shielding layer.