Optical Circuit Package Cavity Layout for Grating Coupler Access
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Solution Overview
Problem
Maintaining optical pathways through circuit packages is challenging, particularly in the manufacturing and implementation of IC architectures, especially for integrated circuits with processors designed for artificial intelligence and machine learning, due to difficulties in interconnecting processor dies, memory dies, and other circuits using optical elements.
Innovation Solution
A circuit package design incorporating an organic interposer with an internal cavity area surrounded by a dam wall, allowing optical access to a grating coupler region, and using underfill material to prevent molding material from entering the cavity while ensuring electrical connections, thereby preserving optical pathways.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If molding material is applied to encapsulate the circuit package, then protection and structural integrity are improved, but optical access to the grating coupler region is blocked
Solution Approach 1:
The circuit package is segmented into multiple regions: a first region containing the grating coupler with optical access, and a second region for electrical components. The molding material selectively encapsulates only the second region, leaving the first region exposed for optical pathways. This spatial segmentation resolves the contradiction by allowing both protection (via molding of non-optical areas) and optical access (via selective non-encapsulation) to coexist.
2Reliability
If underfill material is applied to secure electrical connections, then connection reliability is improved, but the cavity area may be inadvertently filled blocking optical access
Solution Approach 1:
The cavity area is defined and prepared in advance during the substrate formation stage, creating a predetermined space that is inherently protected from underfill material intrusion. By establishing the cavity boundaries before underfill application, the system ensures that subsequent underfilling operations cannot block optical access, thus resolving the contradiction between connection reliability and optical pathway preservation.
Solution Approach 2:
The cavity area acts as an intermediary protective structure between the underfill material and the optical pathway. This intermediate space, formed within the substrate, physically separates the underfill application zone from the optical access zone, allowing underfill to secure electrical connections without compromising optical access to the grating coupler.
3Adaptability or versatility
If optical pathways are maintained through the package, then optical communication capability is preserved, but manufacturing complexity increases
Solution Approach 1:
The optical components (grating coupler) and electrical components are merged into a single integrated circuit package on one substrate. The substrate serves dual functions: as the mechanical support for electrical components and as the optical waveguide structure. This merging eliminates the need for separate optical mounting procedures and aligns optical and electrical interconnects during a single packaging process, thereby reducing manufacturing complexity while preserving optical communication capability.
Data Source
AI summary
The present disclosure relates to example implementations of optically accessible circuit packages. For example, this disclosure includes implementations for creating a circuit package with a photonic integrated circuit (PIC) connected to electrical integrated circuit (EIC) components via an organic interposer. In many implementations, the circuit package maintains optical access to a gating coupler (GC) region on the PIC via an internal cavity area in the organic interposer. In this way, a fiber array unit (FAU) or other optical connection can couple to the circuit package to communicate data from the EIC components of the circuit package and another circuit package or an external device connected to the FAU (e.g., both send and receive data with the cp) via the open access GC region.