Thermal Oxidation for Silicon-on-Insulator Structures
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Solution Overview
Problem
Conventional methods for forming silicon-on-insulator (SOI) structures are expensive, complex, and limited in controlling thickness, with hydrogen ion separation causing particle defects and high energy oxygen implantation resulting in poly-crystalline silicon outside active regions, leading to higher resistances.
Innovation Solution
A method involving a single crystal silicon substrate with a device pattern and a protection layer, where an oxide insulation layer is formed using thermal oxidation to create either full or partial SOI regions, allowing for better control and separation from non-SOI regions, using silicon nitride as a protection layer to prevent oxidation where needed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional methods (wafer bonding, SIMOX, hydrogen ion separation) are used to form SOI structures, then SOI devices can be manufactured, but the manufacturing process becomes expensive and complex
Solution Approach 1:
The invention divides the substrate into distinct SOI regions and non-SOI regions, allowing selective formation of oxide insulation layers only where needed. This segmentation enables simplified processing for non-SOI areas while maintaining SOI benefits in specific device regions, reducing overall manufacturing complexity.
Solution Approach 2:
The patent applies different structural qualities to different regions: oxide insulation layers are formed locally in SOI regions beneath protrusions, while non-SOI regions retain direct substrate contact. This local differentiation allows each region to be optimized for its specific function without requiring complex global processing.
2Manufacturing precision
If conventional methods are used to form SOI structures, then SOI devices can be manufactured, but controlling the thickness of SOI layers becomes difficult
Solution Approach 1:
The invention forms the oxide insulation layer before creating the protrusion structure. By performing the oxidation process on the substrate first, then forming protrusions on top, the thickness of the oxide layer can be precisely controlled through standard thermal oxidation processes before any subsequent processing steps affect the region.
3Reliability
If hydrogen ion separation processes are used, then SOI structures can be formed, but particle defects are introduced in the SOI film and at interfaces
Solution Approach 1:
The invention replaces mechanical/physical separation methods (hydrogen ion separation) with a chemical oxidation process to create the insulation layer. Thermal oxidation chemically transforms silicon at the substrate surface into silicon oxide, eliminating the need for ion bombardment and associated particle defects while achieving the same electrical isolation function.
4Reliability
If high energy oxygen implantation methods are used, then oxide layers can be formed, but silicon material outside active regions becomes poly-crystalline, resulting in higher resistances
Solution Approach 1:
The invention replaces high-energy oxygen implantation (a mechanical/physical process) with thermal oxidation (a chemical process). Thermal oxidation grows oxide layers through controlled chemical reactions at the silicon surface, preserving the single-crystal structure of the underlying silicon and avoiding the poly-crystalline transformation and associated resistance increases.
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 provides a cost-effective, less complex method for forming SOI structures with improved control over thickness, reducing particle defects and maintaining low resistance, while allowing for both SOI and non-SOI devices to be manufactured on traditional substrates with enhanced thermal conductivity.
Implementation Method 1
forming an oxide insulation layer between the protrusion and the substrate using a thermal oxidation process
Implementation Method 2
forming a protection layer on a portion of the protrusion; and forming an oxide insulation layer between the protrusion and the substrate using a thermal oxidation process
Data Source
AI summary
Methods which include providing a single crystal silicon substrate having a device pattern formed on a portion of the substrate where the device pattern has a protrusion, forming a protection layer on a portion of the protrusion, and forming an oxide insulation layer between the protrusion and the substrate using a thermal oxidation process; methods of forming a partial SOI structure which include providing a single crystal silicon substrate having a device pattern formed thereon where the device pattern comprises a non-SOI region and an SOI region having a protrusion, forming a protection layer on a portion of the protrusion, and forming an oxide insulation layer between the protrusion and the substrate using a thermal oxidation process; structures formed by such methods; and partial silicon-on-insulator structures comprising a single crystal silicon substrate having an device pattern disposed on a surface thereof where the device pattern includes a non-SOI region and an SOI region having a protrusion, and an oxide insulation layer disposed in the device pattern where a portion of the insulation layer is disposed under the protrusion such that the protrusion is isolated from the single crystal substrate, and where the non-SOI region is not isolated from the single crystal structure.