Sensing Region Shielding Structure for Stray Light Rejection
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Solution Overview
Problem
Conventional optical sensing devices face issues with stray light or ambient light affecting the signal-to-noise ratio, leading to poor performance, and existing designs complicate the manufacturing process.
Innovation Solution
The introduction of a light shielding layer with specific openings and configurations, including multiple layers of organic and metal materials, reduces the impact of stray light and ambient light, improves adhesion, and simplifies the manufacturing process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a light shielding layer is introduced to reduce stray light and ambient light influence, then the signal-to-noise ratio is improved, but the device complexity increases
Solution Approach 1:
The light shielding layer is divided into multiple segments including a first light shielding layer with a first opening and a second light shielding layer with a second opening. Each segment serves a specific function in blocking stray light while allowing desired light to pass through, thereby improving signal-to-noise ratio without requiring a completely complex shielding structure
Solution Approach 2:
The light shielding layer is configured with different opening positions and sizes at different locations. The first opening is positioned to allow light from the sensing element while the second opening is positioned to block ambient light. This localized optimization of shielding properties improves measurement precision without uniformly increasing device complexity throughout the entire structure
2Measurement precision
If multiple light shielding layers with specific openings are used to block stray light, then the signal-to-noise ratio is improved, but the manufacturing complexity increases
Solution Approach 1:
The first light shielding layer and the second light shielding layer are combined in a stacked configuration where both layers are formed using the same photolithography and etching processes. This merging of multiple shielding functions into a unified manufacturing approach improves signal-to-noise ratio while avoiding the need for separate manufacturing steps for each layer
Solution Approach 2:
The openings in the light shielding layers are pre-configured during the photolithography step before the actual sensing element fabrication. By establishing the light shielding structure early in the manufacturing process with predetermined opening patterns, the subsequent steps are simplified and overall manufacturing complexity is reduced
3Object-affected harmful factors
If the light shielding layer extends beyond the sensing region boundary, then stray light blocking is improved, but the alignment precision requirements increase
Solution Approach 1:
The light shielding layer is extended not only in the horizontal direction beyond the sensing region boundary but also in the vertical stacking dimension with multiple layers. This dimensional extension provides enhanced stray light blocking capability while the vertical stacking allows for more tolerant horizontal alignment since the combined shielding effect of multiple layers compensates for minor misalignments
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
Enhances the signal-to-noise ratio of optical signals, increases sensitivity, and reduces manufacturing complexity by minimizing stray capacitance and alignment difficulties.
Implementation Method 1
The first light shielding layer includes at least one first opening corresponding to the sensing element. The second light shielding layer includes at least one second opening overlapped with the at least one first opening in a top-view direction
Data Source
AI summary
An electronic device having a sensing region and a non-sensing region includes a sensing element, a first light shielding layer and a second light shielding layer. The sensing element is disposed corresponding to the sensing region. The first light shielding layer includes at least one first opening corresponding to the sensing element. The second light shielding layer includes at least one second opening overlapped with the first opening. In a cross-section view, a boundary between the sensing region and the non-sensing region is at an outer side of an edge of a portion of the first light shielding layer, and a horizontal distance between an edge of a portion of the second light shielding layer and the sensing element is greater than or equal to a vertical distance between the portion of the second light shielding layer and the sensing element in a top-view direction of the electronic device.