Capacitive Optical Modulator Thickness Control via Epitaxial Growth
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Solution Overview
Problem
Existing hybrid III-V/Si-type capacitive electro-optical modulators face manufacturing challenges and inefficiencies, particularly in the thickness control of silicon and III-V material strips, which affect the modulation of optical signals.
Innovation Solution
A method of manufacturing a hybrid III-V/Si-type capacitive electro-optical modulator involves etching a cavity in a silicon layer, growing epitaxial layers, defining strips, and bonding III-V materials with an insulating layer to form a capacitive modulator, allowing for precise control of strip thicknesses and improved optical modulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional manufacturing methods are used for hybrid III-V/Si-type capacitive electro-optical modulators, then the manufacturing process is simpler, but the thickness control of silicon and III-V material strips is poor, affecting modulation efficiency
Solution Approach 1:
The manufacturing process is divided into distinct sequential steps: etching a cavity in the silicon layer, growing epitaxial layers, defining strips, depositing insulating layers, and bonding III-V materials. Each step is independently controlled to achieve precise thickness management of different material layers, resolving the contradiction between manufacturing precision and process complexity by organizing the complex process into manageable segments.
Solution Approach 2:
The method performs preliminary actions by first etching a cavity in the silicon layer before growing epitaxial layers, and by defining the silicon strip geometry before bonding the III-V materials. This preliminary structuring enables precise thickness control of subsequent layers and ensures proper optical mode centering, achieving high manufacturing precision while maintaining a systematic approach to the complex manufacturing process.
2Manufacturing precision
If the optical mode is not centered in the waveguide, then the manufacturing is easier, but the charge storage efficiency is reduced, lowering modulation efficiency
Solution Approach 1:
The method changes the thickness parameters of the silicon strip and III-V material strip to achieve optimal optical mode centering. By carefully controlling the thickness of each layer (silicon strip thickness, III-V material strip thickness, and insulating layer thickness), the optical mode is centered in the waveguide to maximize charge storage efficiency and modulation efficiency, while the parameters are chosen to be compatible with standard manufacturing capabilities.
Solution Approach 2:
The waveguide is constructed as a composite structure with alternating layers of silicon, insulating materials, and III-V semiconductors. This composite material approach enables precise control of the optical mode distribution through the layered structure, achieving optimal mode centering by combining materials with different optical properties in a controlled sequence.
3Speed
If thicker strips are used, then the manufacturing is more robust, but the modulation frequency is limited, preventing achievement of >30 GHz
Solution Approach 1:
The method changes the thickness parameters to use thinner strips compared to conventional designs. The silicon strip thickness and III-V material strip thickness are optimized to enable high-speed modulation exceeding 30 GHz by reducing the capacitance and improving the electrical response time, while the structural robustness is maintained through precise fabrication control and appropriate material selection.
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 better modulation efficiency by centering the optical mode for maximum charge storage, increasing the modulation efficiency and allowing for higher modulation frequencies, such as exceeding 30 GHz.
Implementation Method 1
growing in the cavity, by epitaxy from the second layer, a third germanium or silicon-germanium layer; growing in the cavity, by epitaxy from the third layer, a fourth silicon layer to fill the cavity
Implementation Method 2
bonding, by molecular bonding, a layer of III-V materials to the insulating layer
Data Source
AI summary
A semiconductor device can be formed by etching a cavity in a first silicon layer that overlies an insulating layer, epitaxially growing a germanium or silicon-germanium layer in the cavity, epitaxially growing a second silicon layer in the cavity, etching the second silicon layer and the germanium or silicon-germanium layer to the floor of the cavity to define a first strip in the second silicon layer and a second strip in the germanium or silicon-germanium layer, selectively etching a portion of the second strip to decrease the width of the second strip, filling cavity portions arranged on either side of the first and second strips with an insulator, depositing an upper insulating layer over the first and second strips, and bonding a layer of III-V material to the upper insulating layer.