SOI Substrate with Segmented Silicon Thickness for Multi-Transistor Integration
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Solution Overview
Problem
Conventional silicon-on-insulator (SOI) substrates have a uniform thickness of the topmost monocrystalline silicon layer, making it difficult to fabricate different types of transistors with varying device performance and structures on a single substrate, leading to increased manufacturing costs and form factor issues.
Innovation Solution
A method is developed to create an SOI substrate with varying thicknesses of the monocrystalline silicon layer by forming an island-shaped insulating layer, a silicon epitaxial layer, and trenches, followed by bonding with a second semiconductor substrate using insulating adhesive layers, allowing for different transistor types to be fabricated on a single substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a uniform thickness monocrystalline silicon layer is used in conventional SOI substrates, then the manufacturing process is simple, but it is difficult to fabricate different types of transistors with varying device performance and structures
Solution Approach 1:
The monocrystalline silicon layer is segmented into different thickness regions by introducing island-shaped insulating layers at specific positions. This segmentation allows different regions of the substrate to have different silicon layer thicknesses, enabling fabrication of different transistor types (e.g., RF transistors requiring thinner layers and power transistors requiring thicker layers) on the same substrate without requiring multiple separate substrates.
Solution Approach 2:
The patent applies local quality by creating region-specific insulating layers within the monocrystalline silicon substrate. The island-shaped insulating layers are positioned at specific locations to create localized thickness variations, allowing each region to be optimized for specific transistor requirements while maintaining overall substrate integrity.
2Reliability
If different types of transistors are formed on different SOI substrates with different monocrystalline silicon layer thicknesses, then each transistor type can be optimized, but manufacturing costs and form factor increase
Solution Approach 1:
The patent merges multiple transistor types that would traditionally require separate substrates into a single SOI substrate. By integrating different thickness regions within one substrate, the invention combines the functionality of multiple specialized substrates, reducing the total number of substrates needed, lowering manufacturing costs, and decreasing the overall form factor while maintaining optimized performance for each transistor type.
3Adaptability or versatility
If the topmost monocrystalline silicon layer has uniform thickness, then the substrate structure is simple, but it cannot meet the different thickness requirements for different transistor applications
Solution Approach 1:
The patent applies preliminary action by forming the island-shaped insulating layers within the monocrystalline silicon substrate before the final transistor fabrication process. This preliminary structuring establishes the thickness variation pattern in advance, allowing subsequent transistor processing to proceed with precise thickness control in each region without requiring complex real-time adjustments during device fabrication.
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 the fabrication of multiple transistor types on a single SOI substrate, reducing packaging costs and enabling chip-scale packages with reduced feature sizes and improved device performance.
Implementation Method 1
forming a silicon epitaxial layer on the first surface of the first semiconductor substrate so as to cover the island-shaped insulating layer
Implementation Method 2
etching the silicon epitaxial layer using a laser
Implementation Method 3
bonding the first semiconductor substrate and a second semiconductor substrate using the first insulating adhesive layer and a second insulating adhesive layer disposed on the second semiconductor substrate
Data Source
AI summary
A method of manufacturing a silicon-on-insulator (SOI) substrate is provided. The method includes forming an island-shaped insulating layer on a first surface of a first semiconductor substrate in a first region, forming a silicon epitaxial layer on the first surface of the first semiconductor substrate so as to cover the island-shaped insulating layer, forming a trench by etching the silicon epitaxial layer so as to expose the island-shaped insulating layer, and forming a first insulating adhesive layer on the silicon epitaxial layer and the island-shaped insulating layer so as to fill the trench.