Optical Package Structure With Clean Grating Coupler Holes
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Solution Overview
Problem
Current optical signal processing technologies face challenges in efficiently integrating optical and electrical components for signal transmission and processing, particularly in maintaining clean grating coupler holes during the manufacturing of 3D packaging structures, which affects the insertion and alignment of optical elements.
Innovation Solution
The method involves forming a polymer wall structure around the photonic die with a filling material that protects the grating coupler holes during the singulation process, allowing for clean and precise optical element insertion by removing the filling material after singulation, thereby maintaining the integrity of the holes for optical coupling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If encapsulant is formed to fill the structure during packaging, then the packaging structure is completed and protected, but encapsulant fillers contaminate the grating coupler holes and prevent clean optical element insertion
Solution Approach 1:
The encapsulant is segmented into two distinct parts: a first encapsulant material that fills the majority of the packaging structure, and a second encapsulant material (or absence of material) that specifically excludes the grating coupler hole region. This segmentation allows the hole to remain free of contaminating fillers while the rest of the structure receives full encapsulation protection.
Solution Approach 2:
The packaging structure exhibits local quality by having different material compositions in different regions. The grating coupler hole region maintains a specific material composition (free of encapsulant fillers) to enable optical functionality, while surrounding regions contain the encapsulant material for structural protection. This localized material differentiation resolves the conflict between protection and cleanliness.
2Manufacturing precision
If filling material is used to protect grating coupler holes during singulation, then hole cleanliness is maintained, but additional process steps are required to remove the filling material
Solution Approach 1:
The protective function during singulation and the final encapsulant material are merged into a single material system. Instead of using a temporary filling material that must be removed, the same encapsulant material used for final protection is applied in a controlled manner that inherently protects the holes during singulation, eliminating the need for separate filling and removal steps.
Solution Approach 2:
The encapsulant material is applied in a preliminary form that automatically protects the grating coupler holes during the subsequent singulation process. The material placement is pre-configured to exclude the hole regions, so the protection action occurs before any potential contamination can happen, eliminating the need for post-processing removal steps.
3Reliability
If encapsulant fillers are present in grating coupler holes, then encapsulation is complete, but optical element insertion and alignment are compromised
Solution Approach 1:
The encapsulation is segmented to create a clear distinction between protected regions (containing encapsulant fillers) and functional regions (grating coupler holes free of fillers). This segmentation ensures that optical element insertion paths remain clear while the rest of the structure receives complete encapsulation, resolving the conflict between completeness and ease of operation.
Data Source
AI summary
A package structure and methods of forming a package structure are provided. The package structure includes a first die, a second die, a wall structure and an encapsulant. The second die is electrically bonded to the first die. The wall structure is located aside the second die and on the first die. The wall structure is in contact with the first die and a hole is defined within the wall structure for accommodating an optical element. The encapsulant laterally encapsulates the second die and the wall structure.