SiGe Plasma Oxidation for Uniform Nanosheet Spacer Etching
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Solution Overview
Problem
The existing manufacturing process for gate-all-around transistors, such as nanowire or nanosheet transistors, requires multiple high-precision steps, leading to low yield and high costs due to the need for uniform etching of silicon germanium layers, which is inefficient and costly.
Innovation Solution
A substrate processing method using a plasma processing apparatus that selectively modifies the silicon germanium layers by forming an oxide film on their exposed surfaces with a gas mixture containing fluorine and oxygen, allowing for simultaneous etching and oxidation, thereby reducing the number of processing steps required.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple high-precision processing steps are used to uniformly etch silicon germanium layers, then manufacturing precision is improved, but processing time and device complexity increase
Solution Approach 1:
The patent combines multiple separate processing steps (etching and oxidation) into a single plasma processing step by using a mixed gas atmosphere containing fluorine-based etching gas and oxygen-based oxidizing gas. This allows simultaneous formation of oxide films and etching of silicon germanium layers, reducing processing time while maintaining uniformity through controlled gas composition and plasma parameters.
Solution Approach 2:
The patent changes the chemical parameters of the processing atmosphere by introducing a mixed gas system with specific ratios of fluorine-containing gas (e.g., CF4, SF6) and oxygen-containing gas (e.g., O2, N2O). By adjusting gas flow rates, pressure, and plasma power, the process achieves both precise etching and controlled oxidation in one step, resolving the time-precision tradeoff.
2Manufacturing precision
If multiple separate processing steps are used for etching and oxidation, then manufacturing precision is improved, but device complexity increases
Solution Approach 1:
The patent merges sequential etching and oxidation processes into a single plasma processing chamber operation. By introducing both fluorine-based etching gas and oxygen-based oxidizing gas simultaneously into the plasma environment, the process achieves both material removal and oxide film formation in one step, reducing device complexity while maintaining precision through independent gas flow control.
Solution Approach 2:
The plasma processing system is designed to perform multiple functions simultaneously: etching silicon germanium layers, forming oxide films, and controlling deposition rates. This multi-functional approach reduces the number of required processing steps and equipment while maintaining the precision needed for nanowire and nanosheet transistor fabrication.
3Manufacturing precision
If conventional multi-step processing is used, then manufacturing precision is improved, but productivity decreases
Solution Approach 1:
The patent implements continuous useful action by performing etching and oxidation simultaneously in a single plasma processing step rather than sequentially. The mixed gas plasma environment continuously removes silicon germanium material while concurrently forming protective and functional oxide films, eliminating idle time between steps and improving substrate processing throughput while maintaining uniformity.
Solution Approach 2:
By combining multiple discrete processing operations into one integrated plasma step, the patent eliminates the need for intermediate transfer, chamber evacuation, and repressurization cycles. This merging of operations maintains manufacturing precision through controlled gas chemistry while significantly improving productivity by reducing total process time and increasing substrate throughput.
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 method significantly reduces the number of processing steps, improves machining accuracy, and lowers costs by controlling the etching and oxidation of silicon germanium layers, enabling the formation of inner spacers with desired dimensions and properties, such as low leakage current and good insulation characteristics.
Implementation Method 1
forming an oxide film by selectively modifying a surface layer of an exposed surface of the silicon germanium layer by using a processing gas including fluorine and oxygen and converted into plasma
Implementation Method 2
using a processing gas including fluorine and oxygen and converted into plasma
Data Source
AI summary
The present disclosure appropriately shortens a processing step for processing a substrate in which a silicon layer and a silicon germanium layer are alternatively laminated. The present disclosure provides a substrate processing method of processing the substrate in which the silicon layer and the silicon germanium layer are alternatively laminated, which includes forming an oxide film by selectively modifying a surface layer of an exposed surface of the silicon germanium layer by using a processing gas including fluorine and oxygen and converted into plasma.