Dual-Level Image Sensor Structure for Visible and NIR/SWIR Capture
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Solution Overview
Problem
Current semiconductor image sensors struggle to effectively capture a wide range of wavelengths, including visible, near-infrared (NIR), and shortwave infrared (SWIR) light, while preventing signal pollution and maintaining color fidelity, which is essential for both image capture and depth sensing applications.
Innovation Solution
A composite semiconductor image sensor is developed, incorporating a depth-sensing device with a germanium-based light-sensing element for enhanced NIR/SWIR absorption and an image-capturing device with a silicon-based light-sensing element for improved visible light absorption, integrated in a dual-level structure that allows for improved design flexibility and placement, along with a method for forming this sensor that includes specific substrate bonding and interconnect structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single-material light-sensing element is used, then the manufacturing process is simple, but the quantum efficiency across different wavelength ranges (visible, NIR, SWIR) cannot be simultaneously optimized
Solution Approach 1:
The patent employs a composite light-sensing element structure where a germanium layer is deposited on top of a silicon substrate. The silicon layer detects visible light while the germanium layer detects NIR and SWIR wavelengths. This composite material approach enables simultaneous optimization of quantum efficiency across different wavelength ranges by leveraging the complementary spectral response characteristics of silicon and germanium materials.
2Adaptability or versatility
If multiple sensing elements are integrated in a dual-level structure, then the design flexibility and wavelength coverage are improved, but the device complexity increases
Solution Approach 1:
The patent merges multiple light-sensing elements with different spectral responses into a single integrated dual-level structure. The silicon-based sensing element and germanium-based sensing element are combined vertically, with the germanium layer deposited on the silicon substrate. This merging approach achieves broad wavelength coverage and design flexibility while maintaining a relatively simple monolithic structure that can be fabricated using standard semiconductor processing techniques.
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 enables improved quantum efficiency and photon detection efficiency across NIR/SWIR and visible light ranges, achieving comparable resolution and mitigating photon detection efficiency and jitter trade-off issues, while simplifying design and manufacturing.
Implementation Method 1
a depth-sensing device with a germanium-based light-sensing element for enhanced NIR/SWIR absorption
Implementation Method 2
an image-capturing device with a silicon-based light-sensing element for improved visible light absorption
Data Source
AI summary
A semiconductor image sensor includes a first substrate including a first front side and a first back side, and a second substrate including a second front side and a second back side. The first substrate includes a layer and a first light-sensing element in the layer. The layer includes a first semiconductor material, and the first light-sensing element includes a second semiconductor material. The second substrate is bonded to the first substrate with the second front side facing the first back side.