Buried Insulation Regions in Bulk Semiconductor Substrates
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Solution Overview
Problem
The high manufacturing cost and complexity of fabricating silicon-on-insulator (SOI) wafers, particularly due to the limited supply and expense of silicon-on-insulator (SOI) wafers, hinder the widespread use of buried oxide regions in semiconductor devices.
Innovation Solution
A method for forming buried insulation regions within semiconductor substrates using etching and deposition processes, including the formation of epitaxial layers and conductive regions, which allows for the creation of semiconductor devices with reduced manufacturing costs and complexity, utilizing techniques such as isotropic and anisotropic etching, and epitaxial overgrowth to create buried oxide regions without the need for expensive SOI wafers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If SIMOX or wafer bonding processes are used to form buried oxide regions, then the quality and performance of semiconductor devices are improved, but the manufacturing cost and complexity increase significantly
Solution Approach 1:
The patent replaces expensive, limited-supply SOI wafers with readily available bulk semiconductor wafers. The buried oxide region is formed through processing steps (oxidation, etching, deposition) rather than requiring pre-fabricated expensive substrates, effectively substituting a cheap, abundant material with a processed version that achieves the same functional result.
Solution Approach 2:
The patent changes the physical and chemical parameters of bulk semiconductor wafers through oxidation processes to create buried oxide regions. By controlling oxidation conditions, temperature, and time, bulk silicon is transformed into silicon oxide in specific regions, achieving the insulating properties of SOI wafers while starting from inexpensive bulk material.
2Reliability
If SIMOX or wafer bonding processes are used to form buried oxide regions, then the electrical insulation properties are improved, but the device complexity and processing steps increase
Solution Approach 1:
The patent segments the bulk semiconductor wafer by creating isolated buried oxide regions that electrically divide the substrate into separate functional areas. This segmentation achieves the electrical insulation benefits of SOI structures while maintaining compatibility with standard bulk wafer processing techniques.
Solution Approach 2:
The patent performs preliminary oxidation and patterning steps to define where buried oxide regions will form before final device fabrication. By pre-establishing the insulation structures through controlled oxidation and selective removal, subsequent device processing becomes simpler and more straightforward.
3Ease of manufacture
If bulk semiconductor wafers are used instead of SOI wafers, then the manufacturing cost is reduced, but the ability to form buried oxide regions is lost
Solution Approach 1:
The patent introduces oxidation processes and selective etching as intermediary steps that transform bulk semiconductor material into the desired buried oxide structure. These intermediary processes bridge the gap between starting with bulk wafers and achieving the final SOI-like structure with buried oxide regions.
Solution Approach 2:
The patent employs strong oxidizing conditions to rapidly form silicon oxide regions within the bulk semiconductor wafer. By using controlled oxidation processes with appropriate oxidants and temperature conditions, buried oxide regions are created efficiently, enabling bulk wafers to achieve the insulating properties previously only available through expensive SOI substrates.
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 semiconductor devices with buried oxide regions at a lower cost and with greater ease, using bulk semiconductor wafers, thereby overcoming the limitations of traditional SOI wafer fabrication methods, and allows for precise thinning and device formation with improved performance.
Implementation Method 1
An oxide may be formed within the plurality of openings by converting regions of the semiconductor substrate between adjacent ones of the plurality of openings into the oxide
Implementation Method 2
The plurality of openings may be formed by extending through the plurality of second openings using an isotropic etching process
Implementation Method 3
An oxide may be formed within the plurality of openings by converting regions of the semiconductor substrate between adjacent ones of the plurality of openings into the oxide
Implementation Method 4
A semiconductor layer is formed over the buried insulation region at a first side of the substrate
Data Source
AI summary
A method of fabricating a semiconductor device includes forming a buried insulation region within a substrate by processing the substrate using etching and deposition processes. A semiconductor layer is formed over the buried insulation region at a first side of the substrate. Device regions are formed in the semiconductor layer. The substrate is thinned from a second side of the substrate to expose the buried insulation region. The buried insulation region is selectively removed to expose a bottom surface of the substrate. A conductive region is formed under the bottom surface of the substrate.