Waveguide Optical Semiconductor Protrusion Resin Stress
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Solution Overview
Problem
The existing waveguide-type optical semiconductor devices face issues with increased optical loss due to scattering and absorption of light, and stress-related detachment of resin portions from the semiconductor layer, primarily due to differences in thermal expansion coefficients between the semiconductor layer and the resin used for planarization.
Innovation Solution
Incorporating protrusion portions within the stripe-shaped grooves of the waveguide, which reduces the volume of resin buried in the grooves, fixes the relative position of the protrusions, and increases the contact area with other elements, thereby distributing stress uniformly and preventing detachment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If stripe-shaped grooves are filled with resin for planarization, then surface flatness is improved, but stress concentration causes resin detachment from the semiconductor layer
Solution Approach 1:
The groove is divided into two functional zones: a reduced-volume first region containing the protrusion that minimizes stress, and a second region that provides adequate resin coverage for planarization. This segmentation allows the resin to be held securely without excessive stress concentration.
Solution Approach 2:
The groove structure is made non-uniform by introducing a protrusion that creates a localized reduced-volume region. This local modification concentrates the stress-reduction effect where most needed while maintaining overall planarization functionality.
2Reliability
If the volume of resin in grooves is reduced to minimize stress, then resin detachment is prevented, but sufficient planarization and contact area may not be achieved
Solution Approach 1:
The groove is segmented into a first region with reduced volume (containing the protrusion) for stress management, and a second region with adequate volume for planarization. This allows both objectives to be satisfied simultaneously in different zones.
Solution Approach 2:
The protrusion extends in the thickness direction (first direction) to reduce resin volume, while the groove continues in the lateral direction (second direction) to maintain planarization coverage. This dimensional approach allows volume reduction without sacrificing surface flatness.
3Reliability
If protrusions are added to reduce resin volume, then stress is reduced, but device complexity increases
Solution Approach 1:
The groove structure is segmented by adding protrusions that create reduced-volume regions. This segmentation approach systematically manages stress distribution while maintaining a relatively simple overall groove geometry that can be fabricated using standard processes.
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 solution effectively reduces optical loss and prevents resin detachment, enhancing the reliability and performance of the optical semiconductor device by uniformly distributing stress and increasing the contact area with other elements.
Implementation Method 1
the stacked semiconductor layer and the resin differ significantly in thermal expansion coefficient. Thus, stresses are generated in the cured resin portions buried in the stripe-shaped grooves
Data Source
AI summary
A waveguide-type optical semiconductor device includes a substrate with a main surface; a structure including a stacked semiconductor layer including a core layer provided on the main surface of the substrate, a stripe-shaped mesa portion protruding in a first direction orthogonal to the main surface and extending in a second direction parallel to the main surface, and a pair of stripe-shaped grooves defining the stripe-shaped mesa portion and extending in the second direction; a protrusion provided in the pair of stripe-shaped grooves, the protrusion protruding from the structure in the first direction; and a resin portion covering a side face of the protrusion, the resin portion being buried in the stripe-shaped grooves. The relative position of the protrusion with respect to the structure is fixed. In addition, the side face of the protrusion intersects with the second direction when viewed from the first direction.