Light-Receiving Element With Adhered Lens Substrate
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Solution Overview
Problem
Conventional methods for manufacturing light receiving elements with integrated lenses face challenges in precision and reproducibility due to deformation during pedestal formation, making it difficult to achieve the desired lens shape and height.
Innovation Solution
A light receiving element is manufactured by adhering a first substrate with a photodiode to a second semiconductor substrate using a resin adhesive, with a pedestal and lens formed on the second substrate, where the heights of the pedestal and lens are equal, and an ultraviolet curable adhesive is used for provisional bonding followed by thermal curing of the adhesive layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a microlens and pedestal are formed using conventional photolithography and dry etching techniques, then the light receiving element can be manufactured, but the lens shape becomes difficult to control and manufacturing precision deteriorates
Solution Approach 1:
The invention divides the manufacturing process into two independent stages: first forming the microlens shape, then separately forming the pedestal structure. This segmentation allows each component to be optimized independently, preventing the deformation issues that occur when both are formed simultaneously in conventional single-step etching processes.
Solution Approach 2:
The microlens is formed in advance before the pedestal is created. By preliminary forming the lens with precise shape control, subsequent pedestal formation does not interfere with the already-established lens geometry, thereby maintaining manufacturing precision while simplifying the overall process.
2Reliability
If a high pedestal is formed to achieve proper working distance for light condensation, then optical coupling efficiency improves, but lens shape control becomes more difficult
Solution Approach 1:
By separating the pedestal formation from the lens formation process, the invention enables the pedestal to be raised to the necessary height for proper optical coupling without compromising lens shape. The independent timing of these operations eliminates the相互 interference that plagues conventional simultaneous formation methods.
Solution Approach 2:
The lens is formed to its final precise shape before the pedestal is raised to the required height. This preliminary lens formation ensures that subsequent pedestal growth does not deform the lens, while still achieving the necessary working distance for efficient light condensation onto the photodiode.
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 approach allows for the precise and reproducible integration of lenses with photodiodes, eliminating the need for high pedestal heights and enabling efficient optical coupling with minimal loss, thus improving the manufacturing precision and reproducibility of light receiving elements.
Implementation Method 1
a fourth step for provisionally bonding the first substrate to the second substrate by irradiating the ultraviolet curable adhesive with ultraviolet rays in order to cure the ultraviolet curable adhesive
Implementation Method 2
a fifth step for bonding the first substrate to the second substrate by heating the adhesive layer in order to cure the adhesive layer
Data Source
AI summary
A light receiving element includes a first substrate, a photodiode formed on a main surface of the first substrate, and a second substrate constituted by a semiconductor and adhered to a rear surface side of the first substrate by an adhesive layer formed from a resin adhesive. A light receiving element according to an embodiment includes a lens that is formed on the side of an adhesion surface of the second substrate, has a convex surface, and is disposed in a light receiving region of the photodiode. The light receiving side of the photodiode is oriented toward the side of the first substrate. The lens is disposed so that the convex surface thereof is oriented toward the side of a light receiving surface of the photodiode.