3D Die Stack With Staircase Mount For Low-Loss Optical Coupling
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Solution Overview
Problem
Current fiber-to-PIC coupling designs face scalability issues and high bandwidth limitations, with one-dimensional arrays offering high bandwidth and low signal loss but not being scalable, while two-dimensional arrays suffer from higher polarization-dependent loss and coupling losses.
Innovation Solution
A three-dimensional stack of dies with optical edge couplers arranged in a 2D array on the sides and through-substrate vias for interconnection, allowing for precise control of vertical pitch and die thickness variability, enabling low coupling losses and polarization-independent coupling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a one-dimensional array of fiber-to-PIC couplings is used, then high bandwidth communication and low signal loss are achieved, but scalability to many fibers is not possible
Solution Approach 1:
The patent transitions from a one-dimensional array of fiber-to-PIC couplings to a three-dimensional stack of dies configuration. By stacking multiple dies vertically and arranging optical edge couplers on the side surfaces in a two-dimensional array pattern, the system achieves both the low signal loss characteristics of edge couplers and the scalability to multiple fibers through the added vertical dimension.
2Adaptability or versatility
If a two-dimensional array of fiber-to-PIC couplings using vertical grating couplers is used, then scalability to large numbers of fibers is achieved, but polarization-dependent loss and coupling losses increase
Solution Approach 1:
The patent employs a three-dimensional stack of dies with optical edge couplers positioned on the side surfaces of the dies. This configuration enables a two-dimensional array of couplers to be formed while maintaining the low loss characteristics of edge couplers, avoiding the high polarization-dependent loss and coupling losses associated with vertical grating couplers.
3Adaptability or versatility
If a three-dimensional stack of dies with 2D array of optical edge couplers is implemented, then scalability and low coupling losses are achieved, but manufacturing precision requirements increase due to die thickness variability
Solution Approach 1:
The patent introduces a carrier mount with a staircase structure where each step is precisely positioned at a specific height. This local structural feature compensates for die thickness variability by providing a tailored support surface for each die in the stack, ensuring that the vertical pitch between optical edge couplers on adjacent dies remains consistent despite variations in individual die thicknesses.
Solution Approach 2:
The carrier mount with staircase steps acts as an intermediary element between the dies and the substrate. It mediates the vertical positioning of multiple dies with potentially varying thicknesses, ensuring precise vertical pitch control for the optical edge couplers without requiring extremely tight control over each die's thickness during manufacturing.
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
This configuration achieves high bandwidth communication with low signal loss and scalability, combining the advantages of one- and two-dimensional arrays by maintaining low coupling losses and polarization-independent coupling.
Implementation Method 1
optical edge couplers configured to optically couple ends of optical fibers to the dies
Data Source
AI summary
An apparatus including a carrier mount having a staircase of steps in an opening in the carrier mount and a plurality of dies, each one of the dies having at least a portion of an edge of a major surface thereof located on one of the steps corresponding to the one of the dies such that the dies form a stack, major surfaces of the dies being substantially parallel in the stack, each of the dies having one or more electro-optical devices thereon.