Through Silicon Optical Interconnects for High-Frequency Signal Transmission
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Solution Overview
Problem
Existing electrical connections between dice, such as wire bonding and through silicon vias, are not optimal for high signal frequency applications due to power inefficiency and manufacturing complexities, necessitating a more efficient interconnect solution.
Innovation Solution
Through silicon optical interconnects that utilize thin back side layers in dice to transmit optical signals, allowing for power-efficient communication between dice with low parasitic load and reduced manufacturing complications, using optical emitters and receivers integrated into the dice with reflective components for signal direction and scattering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If electrical connections (wire bonding or TSVs) are used to connect dice, then electrical signals can be transmitted between dice, but power efficiency deteriorates and manufacturing complexity increases
Solution Approach 1:
The patent replaces electrical interconnects (wire bonds, TSVs) with optical interconnects. Optical signals transmit data between dice without requiring physical electrical connections through the substrate, eliminating resistive losses and parasitic capacitances inherent in electrical connections, thereby improving power efficiency while simplifying manufacturing
Solution Approach 2:
The patent introduces optical emitters and detectors as intermediary components. Optical emitters convert electrical signals to optical signals that can traverse the die substrate, and optical detectors convert them back. This intermediary optical transmission mechanism avoids direct electrical connections, reducing power loss and manufacturing complexity
2Reliability
If TSVs are used for electrical connection, then dice can be electrically coupled, but manufacturing precision requirements increase and assembly yields decrease
Solution Approach 1:
The patent replaces the mechanical TSV formation process with optical transmission through the die substrate. This eliminates the need for precise TSV drilling, filling, and planarization processes, significantly reducing manufacturing precision requirements and improving assembly yields
Solution Approach 2:
The patent extracts the electrical connection function from the substrate interconnect structure. By using optical signals that can penetrate the die substrate, the patent removes the need for TSVs entirely, eliminating their associated manufacturing precision challenges
3Speed
If traditional electrical interconnects are used, then signal transmission is achieved, but parasitic load increases reducing performance at high frequencies
Solution Approach 1:
The patent substitutes electrical signal transmission with optical signal transmission. Optical signals do not suffer from resistive losses, capacitive coupling, or inductive effects that create parasitic loads in electrical interconnects, enabling superior performance at high signal frequencies
Solution Approach 2:
The patent uses optical emitters and detectors as mediators to convert between electrical and optical domains. The optical transmission path through the die substrate eliminates parasitic electrical effects, while the converter interfaces maintain electrical compatibility with existing circuitry
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 through silicon optical interconnects provide better power efficiency and looser tolerances, leading to improved assembly yields and reduced costs, while eliminating the need for TSVs and waveguides, thus enhancing the connectivity between dice, especially at high signal frequencies.
Implementation Method 1
The back side layer has a thickness that is sufficiently thin to allow an optical signal to traverse through the back side layer
Implementation Method 2
a reflective component for reflecting an optical signal from the optical emitter
Data Source
AI summary
Some implementations provide a semiconductor device that includes a first die and an optical receiver. The first die includes a back side layer having a thickness that is sufficiently thin to allow an optical signal to traverse through the back side layer. The optical receiver is configured to receive several optical signals through the back side layer of the first die. In some implementations, each optical signal originates from a corresponding optical emitter coupled to a second die. In some implementations, the back side layer is a die substrate. In some implementations, the optical signal traverses a substrate portion of the back side layer. The first die further includes an active layer. The optical receiver is part of the active layer. In some implementations, the semiconductor device includes a second die that includes an optical emitter. The second die coupled to the back side of the first die.