Light-Receiving Element Unit With Recessed Stacking
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Solution Overview
Problem
Conventional light receiving element units with stacked light receiving elements face challenges in miniaturization due to increased thickness and manufacturing costs, particularly when using substrates like indium phosphide or gallium nitride, which are more expensive and prone to defects during thinning processes.
Innovation Solution
A light receiving element unit design featuring a first light receiving element with a recess on one side to accommodate a second light receiving element, allowing for stacking without significant thickness increase, and utilizing antireflection layers to minimize light reflection and enhance light reception across a wide wavelength range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If two light receiving elements are stacked to detect different wavelengths, then the wavelength detection capability is improved, but the thickness increases and miniaturization becomes difficult
Solution Approach 1:
The patent applies nesting by placing the second light receiving element inside a recess formed in the first light receiving element. This allows one component to be nested within another, reducing the overall thickness while maintaining the stacked configuration for wavelength detection. The recess is formed to accommodate the second element, enabling miniaturization without sacrificing the dual-wavelength detection capability.
2Length of stationary object
If light receiving elements are thinned by polishing to reduce thickness, then the thickness is reduced, but manufacturing complexity and defect risk increase
Solution Approach 1:
The recess is formed in advance during the manufacturing process of the first light receiving element, before the second element is mounted. This preliminary formation of the recess eliminates the need for subsequent thinning operations on the stacked structure, reducing manufacturing complexity and defect risk while achieving the desired thickness reduction.
3Reliability
If expensive substrates like indium phosphide or gallium nitride are used for light receiving elements, then the light reception performance is improved, but the manufacturing cost increases
Solution Approach 1:
The patent applies local quality by using different substrate materials for different light receiving elements based on their specific wavelength detection requirements. The first light receiving element uses one type of substrate optimized for its wavelength range, while the second element uses another substrate material suited for its wavelength range. This selective material assignment optimizes performance for each element's specific function while managing overall manufacturing costs.
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 design enables the miniaturization of the light receiving element unit while maintaining effective light reception across different wavelengths, reducing manufacturing costs by utilizing a silicon substrate for the first element and an indium phosphide or gallium nitride substrate for the second element, without the need for extensive thinning.
Implementation Method 1
utilizing antireflection layers to minimize light reflection and enhance light reception across a wide wavelength range
Implementation Method 2
two types of light receiving elements that convert light of different wavelength ranges into electrical signals
Data Source
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AI summary
The light receiving element unit (1, 1A, 101) includes a first light receiving element (10, 110) having a light receiving region on the main surface side of the first semiconductor substrate and a second light receiving element having a light receiving region on the main surface side of the second semiconductor substrate(20, 120), and a support substrate (2,102) having wiring for electrically connecting the first light receiving element and the second light receiving element to the outside, one of the first light receiving element and the second light receiving element has a recess (16, 126) formed in a concave shape from the back surface opposite to the light receiving region toward the light receiving region, and the other is accommodated in the recess.