Semiconductor Waveguide Integration in Transistor Regions
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Solution Overview
Problem
The integration of photodevices and transistors on the same integrated circuit faces challenges due to differences in required technologies, leading to compromises in performance, space efficiency, and process complexity, with a need for a solution that optimizes both performance and space usage without separate processes.
Innovation Solution
A semiconductor structure with a transistor and photodevice separated by an isolation region, utilizing a double semiconductor-on-insulator (SOI) structure and epitaxial growth to create a continuous semiconductor waveguide with specific dimensions for efficient light transmission, allowing for simultaneous integration and optimization of both device types.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If photodevices and transistors are integrated on the same circuit, then functionality and performance are improved, but process complexity increases due to different technology requirements
Solution Approach 1:
The patent uses a unified semiconductor fabrication process that can manufacture both photodevices and transistors using the same layers and steps. The waveguide structure, formed from the same semiconductor layers as the transistor, serves dual purposes as both an optical transmission medium and a structural element compatible with standard CMOS processing, eliminating the need for separate fabrication processes
Solution Approach 2:
The patent optimizes specific dimensional parameters of the waveguide structure (width between 0.5-5 micrometers, height between 0.1-2 micrometers) and semiconductor layer thicknesses to simultaneously achieve proper optical confinement for photodevice operation and compatibility with standard transistor fabrication processes, resolving the conflict between optical performance and manufacturing simplicity
2Area of stationary object
If space is minimized for device integration, then area efficiency is improved, but performance may be compromised due to dimensional constraints
Solution Approach 1:
The patent moves the optical confinement from a purely lateral (2D) structure to a vertical (3D) structure by creating an embedded waveguide where the semiconductor layer itself forms the confining structure. This vertical confinement allows for compact lateral dimensions while maintaining proper optical mode confinement, achieving both small footprint and high performance
Solution Approach 2:
The waveguide structure is nested within the semiconductor layers that also form the transistor structure. The same semiconductor material and layers serve dual functions: as the active region for transistors and as the waveguide core for optical transmission, maximizing space utilization without compromising either device type's performance
3Reliability
If separate processes are used for photodevices and transistors, then device optimization is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The patent demonstrates that standard CMOS fabrication processes can be used to create both transistors and photodevices with optimized performance. The same deposition, etching, and doping steps that form transistors also create the waveguide structure, eliminating the need for specialized photodevice fabrication processes while maintaining high optical performance
Solution Approach 2:
The patent merges the fabrication processes for transistors and photodevices into a single unified process flow. The waveguide is formed as an integral part of the semiconductor structure during standard transistor fabrication, combining what were previously separate manufacturing operations into one cohesive process that simplifies manufacturing while optimizing both device types
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 enables efficient use of space, improved performance, and simplified processing, allowing for high-performance photodevice and transistor integration with minimal performance tradeoffs, suitable for high-speed systems with potential for reduced interference.
Implementation Method 1
a continuous semiconductor waveguide with specific dimensions for efficient light transmission
Implementation Method 2
utilizing a double semiconductor-on-insulator (SOI) structure and epitaxial growth to create a continuous semiconductor waveguide
Data Source
AI summary
A semiconductor structure having a transistor region and an optical device region includes a transistor in a first semiconductor layer of the semiconductor structure, wherein the first semiconductor layer is over a first insulating layer, the first insulating layer is over a second semiconductor layer, and the second semiconductor layer is over a second insulating layer. A gate dielectric of the transistor is in physical contact with a top surface of the first semiconductor layer, and the transistor is formed in the transistor region of the semiconductor structure. A waveguide device in the optical device region and a third semiconductor layer over a portion of the second semiconductor layer.