Photonic Assembly Layout for Bonding Yield Without Optical Blockage
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Solution Overview
Problem
Existing photonic integrated circuits (PICs) face challenges in achieving high bonding yield and integration with electronic integrated circuits (EICs, particularly due to optical path blockage and insufficient bonding strength between components.
Innovation Solution
A photonic assembly is developed with a dielectric pillar structure in the optical path, where metal bonding pads are arranged to surround and overlap with the optical path, enhancing bonding strength through metal-to-metal bonding and dielectric-to-dielectric hybrid bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If metal bonding pads are placed in the optical path area to enhance bonding strength, then bonding yield improves, but optical path transmission deteriorates due to blockage
Solution Approach 1:
The bonding pad structure is segmented into two types: first bonding pads located outside the optical path area and second bonding pads located within the optical path area. This segmentation allows the second bonding pads to contribute to bonding strength without completely blocking the optical path, as the optical beam can pass through the transparent or translucent dielectric material surrounding the second bonding pads or through gaps between them.
Solution Approach 2:
A transparent or translucent dielectric material is introduced as an intermediary between the second bonding pads and the optical path. This dielectric material allows optical transmission while providing a substrate for the bonding pads, thus mediating between the conflicting requirements of bonding strength and optical transmission.
2Reliability
If bonding pad area is increased to improve bonding strength, then bonding yield improves, but device area increases
Solution Approach 1:
The bonding pad configuration utilizes both the planar dimension (first bonding pads outside optical path) and the vertical/dielectric layer dimension (second bonding pads within optical path area but in transparent material). This dimensional approach allows increased bonding pad area without proportionally increasing the overall device footprint, as the second bonding pads are embedded within the existing optical path area rather than extending it.
Data Source
AI summary
A photonic assembly includes: an electronic integrated circuits (EIC) die including a semiconductor substrate, semiconductor devices located on a horizontal surface of the semiconductor substrate, first dielectric material layers embedding first metal interconnect structures, a dielectric pillar structure vertically extending through each layer selected from the first dielectric material layers, a first bonding-level dielectric layer embedding first metal bonding pads, wherein a first subset of the first metal bonding pads has an areal overlap with the dielectric pillar structure in a plan view; and a photonic integrated circuits (PIC) die including waveguides, photonic devices, second dielectric material layers embedding second metal interconnect structures, a second bonding-level dielectric layer embedding second metal bonding pads, wherein the second metal bonding pads are bonded to the first metal bonding pads.