Bridged Integrated Optical Waveguide for Low-Loss Chip Interconnects
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Solution Overview
Problem
The increasing demand for data computation in data centers and high-performance computing units is hindered by the energy consumption and bandwidth limitations of electrical interconnects, with metal interconnects becoming a bottleneck for further scaling and preventing the full benefit of technological advancements.
Innovation Solution
An integrated optical waveguide with a core and surrounding material of the same substrate, connected by bridges, which allows for high mechanical stability, reduced production costs, and improved performance through reduced sidewall roughness and transmission losses, compatible with CMOS technology.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If electrical interconnects are used for intra- and interchip communication, then data transmission is achieved, but energy consumption increases and bandwidth limitations occur
Solution Approach 1:
The patent substitutes electrical interconnects with optical waveguides for data transmission. The optical waveguide uses light instead of electrical signals to transmit data between chips, thereby reducing energy consumption and increasing bandwidth capacity. This is achieved by integrating optical components directly into the chip structure, replacing the traditional electrical interconnect architecture.
2Ease of manufacture
If through-silicon vias are drilled and filled with resin cladding-core system, then optical interconnection is achieved, but mechanical stability decreases and production complexity increases
Solution Approach 1:
The patent merges the core and cladding structures by forming them as an integrated unit within the substrate using selective etching. Instead of separately drilling vias and filling them with resin, the optical waveguide structure is created directly in the substrate material, eliminating the need for separate filling operations and improving mechanical stability while simplifying the manufacturing process.
3Productivity
If laser drilling is used to create vias for ball lens embedding, then optical coupling is achieved, but integration density decreases
Solution Approach 1:
The patent replaces laser drilling with selective etching processes to create the optical waveguide structures. This substitution allows for precise control of the waveguide dimensions and geometry, enabling higher integration density while maintaining the required optical coupling performance. The etching process can create smaller, more precisely defined structures compared to laser drilling.
4Reliability
If polymer filling is used in optical TSVs, then light confinement is improved, but transmission losses increase due to impedance mismatch
Solution Approach 1:
The patent changes the refractive index parameters of the waveguide structure by using the substrate material itself with appropriate etching patterns. This eliminates the impedance mismatch problem associated with polymer filling while maintaining effective light confinement through the geometric configuration of the waveguide. The refractive index contrast is optimized through the etching depth and pattern rather than material composition.
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 integrated optical waveguide supports high data rates and connection densities, enabling efficient optical connections between chips, reducing energy consumption, and overcoming bandwidth limitations.
Implementation Method 1
etching the integrated optical waveguide with an anisotropic plasma process in an axial direction into the substrate
Implementation Method 2
a refractive index difference between the first refractive index and the second refractive index allows to guide light within the core
Data Source
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AI summary
The present invention regards an integrated optical waveguide (1000) formed in a substrate (10). The integrated optical waveguide (1000) includes a hole (12'), a core (14'), and one or more bridges (16'). The hole (12') extends in an axial direction (z) of the substrate (10). The core (14') is made of the same material as the substrate (10), arranged in the hole (12'), and extends in the axial direction (z). The core (14) has a first refractive index and a sidewall (15') which is at least partly surrounded by a surrounding material (20') which has a second refractive index which is lower than the first refractive index and such that a refractive index difference between the first refractive index and the second refractive index allows to guide light within the core (14'). The one or more bridges (16') extend from the sidewall (15') of the core (14') to a sidewall (18') of the hole (12'). The one or more bridges (16') may also be made of the same material as the substrate (10). Furthermore, one or more of the sidewalls (15'; 17a', 17b'; 18') of the core (14'), the hole (12'), and the one or more bridges (16') may be tapered sidewalls (15'; 17a', 17b'; 18') which include a section which is oblique to the axial direction (z). Additionally an axial length (12) of one or more of the one or more bridges (16') may be shorter than an axial length (l1) of the core (14').