Photonic IC Seal Ring Layout for Dicing Stress and Edge Coupling
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Solution Overview
Problem
Integrated circuits, particularly photonic integrated circuits, face challenges in protecting internal circuitry from damage during the wafer dicing process, which can lead to cracking and delamination due to stress, and existing seal ring structures may not effectively shield the internal components while allowing optical signal exchange.
Innovation Solution
A seal ring structure is integrated into the photonic integrated circuit, comprising multiple dielectric and conductive layers, which surrounds the interconnection structure and silicon waveguides, providing stress protection during sawing operations while enabling optical signal exchange through edge-coupling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a seal ring structure is added to protect internal circuitry from stress during dicing, then stress protection and structural integrity are improved, but device complexity increases
Solution Approach 1:
The seal ring structure is divided into multiple segments or sections that can be formed through sequential processing steps. This segmentation allows the protective function to be distributed across multiple smaller structural elements rather than requiring a single complex continuous ring, thereby reducing overall structural complexity while maintaining stress protection capability.
Solution Approach 2:
The seal ring structure is formed preliminarily during the semiconductor fabrication process before the dicing operation. By pre-forming this protective structure while the wafer is still in a manageable state, the complexity of adding protection later is avoided, and the structure is integrated into the manufacturing flow without requiring additional complex post-processing steps.
2Reliability
If the seal ring structure covers a large area (80-99% of surface) to maximize protection, then stress protection is improved, but manufacturing precision requirements increase
Solution Approach 1:
The seal ring structure serves multiple functions simultaneously: it provides stress protection during dicing, defines the active circuit area, and serves as a reference for subsequent processing steps. By combining these functions into a single universal structure, the need for multiple separate precision-aligned features is eliminated, reducing overall manufacturing precision requirements while maintaining comprehensive coverage for protection.
3Device complexity
If existing seal ring structures are used, then device complexity is kept low, but stress protection effectiveness is insufficient
Solution Approach 1:
The seal ring structure employs composite material construction, combining different dielectric layers and conductive materials to achieve both mechanical stress protection and electrical functionality. This composite approach provides enhanced protection effectiveness compared to simple single-material rings, while the materials are selected and structured to avoid excessive complexity in fabrication.
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 seal ring structure effectively protects the photonic integrated circuit from stress during sawing, maintaining structural integrity and enabling efficient optical signal transmission, with a coverage area of approximately 80% to 99% of the circuit's surface.
Implementation Method 1
enabling optical signal exchange through edge-coupling
Data Source
AI summary
A photonic integrated circuit has a central region and a peripheral region surrounding the central region. The photonic integrated circuit includes a semiconductor layer, a seal ring structure, and a plurality of silicon waveguides. The seal ring structure is disposed on the semiconductor layer. The seal ring structure is located in the peripheral region and has at least one recess recessing towards the central region from a top view. The seal ring structure is a continuous structure from the top view. The silicon waveguides are embedded in the semiconductor layer.