Mid-Infrared Optical Interconnection for Stacked Semiconductor Chips
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Solution Overview
Problem
Current semiconductor chip stacking technologies, such as wire bonding and Through Silicon Via (TSV), face challenges with increasing complexity, high costs, and low yield due to the need for metal wiring, which limits the number of layers that can be stacked and is sensitive to manufacturing errors, and existing optical interconnection methods are hindered by wavelength absorption by next-generation semiconductor materials.
Innovation Solution
The method employs optical interconnection using a mid-infrared wavelength range of light that is transparent to silicon and next-generation high-mobility materials, enabling direct information transmission and reception between stacked semiconductor chips without physical connections, utilizing a laser and photo-sensor on substrates made of silicon, germanium, and III-V compounds, and integrating optical transmitters and detectors through an epitaxial lift-off process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If metal wiring (wire bonding or TSV) is used for interconnection, then electrical connection between chips is achieved, but device complexity and manufacturing cost increase with the number of layers
Solution Approach 1:
The patent replaces the mechanical/electrical wiring system (metal wires, TSV structures) with an optical system using photons for information transmission. This substitution eliminates the need for complex metal interconnections between stacked chips, reducing wiring complexity while maintaining reliable communication through optical signals that pass through the substrate materials.
Solution Approach 2:
The patent introduces optical transmitters and optical detectors as intermediary devices that convert electrical signals to optical signals and back. These intermediaries enable communication between stacked chips without direct electrical contact, simplifying the interconnection architecture by removing the need for complex metal wiring while maintaining signal transmission capability.
2Quantity of substance
If the number of stacked semiconductor chips is increased, then integration density is improved, but heat generation and interference increase
Solution Approach 1:
The patent replaces electrical signal transmission through metal wires with optical signal transmission through photons. This substitution reduces heat generation because optical signals do not suffer from resistive heating effects, and reduces electromagnetic interference since photons do not generate electromagnetic fields that can interfere with adjacent circuits, enabling higher stacking densities.
3Ease of manufacture
If TSV technology is used for interconnection, then manufacturing process is simplified, but alignment precision requirements increase
Solution Approach 1:
The patent introduces optical transmitters and detectors as intermediary components that are integrated onto the chip surfaces. These intermediaries enable optical coupling between stacked chips without requiring precise mechanical alignment of through-silicon vias, as the optical coupling can be achieved through proximity coupling or waveguide structures that are more tolerant to misalignment.
4Reliability
If conventional optical interconnection wavelengths (1.3 μm, 1.55 μm) are used, then optical transmission is achieved, but absorption by semiconductor materials occurs
Solution Approach 1:
The patent changes the wavelength parameter of the optical signal from conventional near-infrared wavelengths (1.3 μm, 1.55 μm) to mid-infrared wavelengths (3-6 μm). This parameter change exploits the transparency window of silicon and other semiconductor materials in the mid-infrared region, reducing absorption losses and enabling optical interconnection through stacked semiconductor chips.
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 approach allows for efficient interconnection between stacked semiconductor chips, reducing bandwidth and power consumption, overcoming the limitations of TSV technology, and eliminating the need for substrate perforation and alignment, thereby lowering costs and improving manufacturing ease.
Implementation Method 1
converting an electrical signal to an optical signal, transmitting the optical signal to a second substrate disposed above or below a first substrate using an optical transmitter provided on the first substrate
Implementation Method 2
receiving the optical signal using an optical detector provided on the second substrate, and converting the received optical signal to an electrical signal
Implementation Method 3
a wavelength range (for example, 1.3 μm, 1.55 μm) of light generally used for interconnection is blocked/absorbed by next-generation semiconductor materials having high mobility such as SiGe, Ge and InGaAs
Implementation Method 4
a wavelength range having transmittance more than a threshold for the first substrate and the second substrate may be selected
Data Source
AI summary
A method for optical interconnection between semiconductor chips according to an embodiment include converting an electrical signal to an optical signal, transmitting the optical signal to a second substrate disposed above or below a first substrate using an optical transmitter provided on the first substrate, receiving the optical signal using an optical detector provided on the second substrate, and converting the received optical signal to an electrical signal. Accordingly, using a mid-infrared wavelength range of light that is transparent to semiconductor materials such as silicon and next-generation high-mobility materials, it is possible to enable interconnection between stacked semiconductor chips without using metal wiring. Using optical interconnection, it is possible to significantly reduce the bandwidth and power consumption, and overcome the limitations of TSV technology, and it is possible to extend the photonics technology and platform established in the existing Si Photonics, thereby reducing the cost required for design.