Self-Aligned Waveguide Mirrors for Low-Loss Chip-to-Chip Links
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Solution Overview
Problem
Existing optical waveguides in electronic packaging suffer from significant optical losses due to alignment offsets caused by multiple patterning operations, which hinder efficient chip-to-chip communications.
Innovation Solution
Implementing self-aligned reflective surfaces on opposite ends of the optical waveguide, allowing for a lateral path and minimizing optical losses through total internal reflection, with materials having a higher index of refraction than the package substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple patterning operations are used to route waveguide signals, then routing capability is improved, but alignment offset increases causing optical losses
Solution Approach 1:
The method performs alignment marking before the waveguide routing patterning operations. By pre-establishing alignment references on the substrate, subsequent patterning steps can maintain precise registration without accumulating alignment offsets, thereby enabling complex routing while minimizing optical losses.
Solution Approach 2:
The system uses self-aligned patterning where the waveguide structures automatically register to the pre-marked alignment features. This self-service mechanism eliminates the need for separate alignment procedures between patterning steps, ensuring consistent positioning and reducing alignment-induced optical losses while maintaining routing flexibility.
2Adaptability or versatility
If multiple patterning operations are performed, then waveguide routing flexibility is improved, but manufacturing precision deteriorates due to alignment offset
Solution Approach 1:
Alignment marks are established on the substrate before any waveguide patterning operations. These pre-created references serve as permanent benchmarks that all subsequent patterning steps can register to, ensuring that even complex multi-step routing patterns maintain precise alignment and geometric accuracy.
Solution Approach 2:
The invention replaces mechanical alignment procedures with an optical/self-aligned system where patterned features automatically register to pre-marked alignment structures. This substitution eliminates mechanical alignment errors and ensures consistent manufacturing precision across multiple patterning operations.
3Ease of manufacture
If conventional waveguide routing is used, then manufacturing simplicity is maintained, but optical transmission efficiency deteriorates
Solution Approach 1:
The method adds a preliminary alignment marking step that enables precise self-aligned patterning throughout the waveguide fabrication process. This single additional step establishes reference features that guide all subsequent routing operations, ensuring optimal alignment and minimal optical losses while maintaining overall manufacturing simplicity through the self-aligned approach.
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 self-aligned reflective surfaces effectively reduce optical losses, enabling efficient routing of signals between dies within the package substrate, enhancing chip-to-chip communication performance.
Implementation Method 1
The first end and the second end have reflective structures that are self-aligned to route an optical signal from within the waveguide to overlying dies
Data Source
Figure 1A~1B
Figure 2A~3A
Figure 3B~3D
AI summary
Embodiments disclosed herein include electronic packages and methods of forming such structures. In an embodiment, an electronic package comprises a package substrate, a first die over the package substrate, and a second die over the package substrate. In an embodiment, the electronic package further comprises an optical waveguide on the package substrate. In an embodiment, a first end of the optical waveguide is below the first die and a second end of the optical waveguide is below the second die. In an embodiment, the optical waveguide communicatively couples the first die to the second die.