Self-Aligned Interposer Structures for PIC Optical Coupling
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The integration of optoelectrical devices, such as semiconductor lasers and photodiodes, into photonic integrated circuits (PICs) requires precise alignment of optical and electrical features, which is challenging due to the incompatibility of alignment structures on mounted die and substrates, leading to increased manufacturing complexity and potential coupling losses.
Innovation Solution
The use of mechanical alignment aids, including z-pillars, fiducials, and lateral constraints, formed on both the substrate and optoelectrical devices to facilitate vertical and lateral alignment of optical pathways, enabling efficient transfer of optical signals between devices in PICs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If pre-formed optoelectrical die are integrated into PICs, then functionality is improved, but alignment precision deteriorates due to incompatibility of alignment structures
Solution Approach 1:
The patent introduces alignment reference structures (such as alignment marks, alignment pins, or alignment grooves) as intermediary elements that mediate between the substrate and the mounted optoelectrical die. These reference structures provide a common alignment framework that is compatible with both the substrate's alignment system and the die's alignment system, enabling precise registration without requiring direct compatibility between the two different alignment structures.
Solution Approach 2:
The alignment reference structures are formed on the substrate before the optoelectrical die are mounted. This preliminary formation of alignment references allows the alignment process to be simplified during assembly, as the references are already in place to guide the positioning and alignment of the mounted die, thereby improving alignment precision without complicating the overall manufacturing process.
2Manufacturing precision
If active alignment techniques are used, then alignment precision is improved, but manufacturing complexity and time increase
Solution Approach 1:
The alignment reference structures are designed to enable self-alignment during the mounting process. The structures themselves provide the guiding and positioning functions, allowing the optoelectrical die to be automatically aligned with the substrate features without requiring complex active alignment equipment or procedures. This self-service approach eliminates the need for sophisticated active alignment systems while maintaining high alignment precision.
Solution Approach 2:
The patent replaces complex active alignment mechanisms (such as adjustable mounting stages, real-time feedback systems, or complex positioning equipment) with simpler passive alignment reference structures. These mechanical or geometric references provide the necessary alignment guidance through their physical presence and geometric relationships, substituting the need for complex active mechanical alignment systems.
3Manufacturing precision
If alignment structures are formed on both substrate and die, then alignment precision is improved, but device complexity increases
Solution Approach 1:
The alignment reference structures are designed with local quality variations that provide different functional characteristics at different locations. For example, alignment marks may have specific geometric patterns that provide lateral alignment guidance, while alignment pins or grooves provide vertical positioning. This localized differentiation of alignment structure qualities enables precise multi-dimensional alignment without requiring uniform complex structures throughout the entire substrate or die.
Solution Approach 2:
The alignment system is segmented into separate reference structures with distinct functions. Rather than using a single complex alignment mechanism, the patent employs multiple simpler reference elements (such as separate alignment marks for lateral alignment and alignment pins for vertical alignment) that work together to provide comprehensive alignment. This segmentation reduces the complexity of individual components while achieving the same overall alignment precision.
Data Source
AI summary
Alignment aid structures and the method of formation of these structures on an interposer comprised of a planar waveguide layer and a base structure, facilitate the alignment of the optical axes of optical and optoelectrical devices formed from and mounted to the interposer. Alignment aids formed from a common hard mask on the planar waveguide layer of the interposer structure include vertical and lateral alignment structures and fiducials. Optical losses for signals propagating in interposer-based photonic integrated circuits are reduced with effective alignment structures and methods.