Optical Interconnection Unit for Stacked Silicon Chips
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Solution Overview
Problem
In multi-chip structures, existing connection methods such as wire bonding and through silicon via hole connections face challenges like signal delay, increased bonding pad area, and complexity, while optical connections are hindered by the thickness of light emitting and receiving devices, making it difficult to achieve a compact package.
Innovation Solution
The implementation of an optical interconnection unit with arrays of light emitting and receiving devices on the side surfaces of silicon chips, using vertical cavity surface emitting lasers and p-n junction photodiodes, along with focusing lenses, to reduce inter-chip distance and facilitate optical signal transmission between stacked chips.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wire bonding method is used for electrical connection between silicon chips, then electrical connection is achieved, but signal delay occurs and bonding pad area increases
Solution Approach 1:
The patent replaces the mechanical wire bonding system with an optical transmission system. Light emitting devices and light receiving devices are used to transmit signals optically between chips, eliminating the need for physical wire bonds and large bonding pads. This substitution resolves the contradiction by achieving reliable signal transmission without increasing bonding pad area.
Solution Approach 2:
The patent transitions from planar wire bonding connections to three-dimensional optical path connections. By using light emitting and receiving devices positioned on chip surfaces, signals can be transmitted through air or optical media in three-dimensional space, eliminating the constraint of requiring large surface area bonding pads for electrical connections.
2Reliability
If through silicon via hole connection method is used, then RC delay is reduced and power consumption is minimal, but manufacturing process becomes complicated
Solution Approach 1:
The patent replaces the complex mechanical through-silicon-via fabrication process with an optical transmission system. Instead of creating physical holes through silicon substrates and filling them with conductive materials, the invention uses light emitting and receiving devices to transmit signals optically, thereby achieving efficient signal transmission with simpler manufacturing processes.
3Reliability
If optical interconnection units with light emitting and receiving devices are installed on facing chips, then optical connection is achieved, but inter layer distance increases
Solution Approach 1:
The patent changes the operational parameters of light emitting and receiving devices to enable shorter transmission distances. By optimizing the emission wavelength, detection sensitivity, and optical coupling efficiency, the system achieves reliable optical connections with reduced inter-layer distances, allowing thinner chip packages while maintaining optical connection reliability.
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 reduces the vertical distance between chips, enhances signal transmission speed, minimizes wire bondings, and simplifies manufacturing by allowing optical communication without increasing chip thickness, while maintaining a compact package design.
Implementation Method 1
a light emitting device and a light receiving device may be installed on chips facing each other
Implementation Method 2
a light emitting device and a light receiving device may be installed on chips facing each other
Implementation Method 3
a focusing lens formed on a surface of the light emitting device
Data Source
AI summary
A multi-chip having an optical interconnection unit is provided. The multi-chip having an optical interconnection unit includes a plurality of silicon chips sequentially stacked, a plurality of optical device arrays on a side of each of the plurality of the silicon chips such that the optical device arrays correspond to each other and a wiring electrically connecting the silicon chip and the optical device array attached to a side of the silicon chip, wherein the corresponding optical device arrays forms an optical connection unit by transmitting and receiving an optical signal between the corresponding optical device arrays in different layers. Each of the optical device arrays includes at least one of a light emitting device and a light receiving device.