Silicon-Based Single-Crystal Formation Selectivity
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Solution Overview
Problem
Existing processes for forming silicon-based single-crystal portions on substrates face challenges with deposition selectivity, requiring narrow temperature and pressure ranges, leading to poor reproducibility and long processing times, especially when dealing with mixed substrate zones containing single-crystal and insulating materials.
Innovation Solution
A process using a non-chlorinated silicon hydride as a precursor, combined with a carrier gas, to form a silicon-based layer selectively on single-crystal zones while forming an amorphous layer on insulating zones, followed by selective etching to maintain the single-crystal portion, allowing for lower substrate temperatures and faster deposition with improved selectivity and uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If dichlorosilane is used as precursor for selective epitaxial growth, then single-crystal portions are formed on single-crystal substrate zones, but the process requires narrow temperature and pressure ranges leading to poor reproducibility
Solution Approach 1:
The patent changes the chemical parameters of the deposition process by replacing dichlorosilane with non-chlorinated silicon hydride precursors (such as silane, disilane, or trisilane). This fundamental parameter change in the precursor chemistry enables broader process windows for temperature and pressure while maintaining selective epitaxial growth on single-crystal zones and amorphous deposition on insulating zones, thereby improving reproducibility without sacrificing selectivity.
2Manufacturing precision
If dichlorosilane is used with low growth rate, then selective deposition is achieved, but long deposition times reduce fabrication output
Solution Approach 1:
The patent changes the kinetic parameters of the deposition process by using non-chlorinated silicon hydride precursors that exhibit significantly higher reaction rates and growth speeds compared to dichlorosilane. This parameter change in precursor reactivity enables fast deposition while preserving selective epitaxial growth on single-crystal substrate zones, thereby increasing fabrication output without compromising deposition selectivity.
3Manufacturing precision
If high substrate temperature is used for selective deposition, then satisfactory selectivity is achieved, but thermal impact on existing circuit components increases
Solution Approach 1:
The patent changes the thermal parameters of the deposition process by using non-chlorinated silicon hydride precursors that enable selective epitaxial growth at lower substrate temperatures compared to dichlorosilane-based processes. This parameter change in process temperature reduces the thermal budget and minimizes thermal impact on existing sensitive circuit components and fragile materials while maintaining adequate deposition selectivity between single-crystal and insulating zones.
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 results in more reproducible and efficient formation of single-crystal layers with reduced thermal impact on existing circuit components, enabling the use of fragile materials and achieving uniform thickness across the substrate with enhanced selectivity and precision.
Implementation Method 1
The deposition process most often used for epitaxial growth is CVD (chemical vapor deposition). The layer is then formed from gaseous precursor compounds that are brought into contact with the surface of the substrate and chemically react thereon.
Implementation Method 2
The single-crystal parts of the substrate serve as seeds for forming the portions. Such a way of forming the portions is called epitaxial growth.
Implementation Method 3
The deposition parameters comprise the partial pressures of the gaseous compounds, the temperature of the substrate and the amount of hydrogen chloride (HCl) that is added to the mixture.
Implementation Method 4
b/ etching selectively the silicon-based layer formed in step a so that an amorphous portion of said layer formed in the second substrate zone is removed and a substantially single-crystal portion of said layer, formed in the first substrate zone, remains substantially intact
Data Source
AI summary
Silicon-based single-crystal portions are produced on a surface of a substrate, selectively in zones where a single-crystal material is initially exposed. To do this, a layer is firstly formed over the entire surface of the substrate, using a silicon precursor of the non-chlorinated hydride type, and under suitable conditions so that the layer is a single-crystal layer in the zones of the substrate where a single-crystal material is initially exposed and amorphous outside these zones. The amorphous portions of the layer are then selectively etched so that only the single-crystal portions of the layer remain on the substrate.