Selective SiGe Etching with Passivation to Protect Underlayers
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Solution Overview
Problem
Conventional etching processes struggle to selectively remove one silicon-and-germanium-containing material relative to another in semiconductor manufacturing, often leading to undesirable etching of underlying materials.
Innovation Solution
A method involving selective oxidation and the use of a passivation precursor with an etchant precursor to form a passivation material, which prevents etching of underlying materials while selectively removing silicon-and-germanium-containing materials with different germanium concentrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional etching processes are used to remove silicon-and-germanium-containing material, then etching speed is improved, but selectivity deteriorates causing unwanted etching of underlying layers
Solution Approach 1:
The patent applies preliminary oxidation to the silicon-and-germanium-containing material before etching. This oxidation step creates a modified surface layer that etches at a different rate than the underlying material, enabling selective removal. The oxidation is performed in advance to prepare the material for selective etching, which resolves the contradiction by pre-modifying the target material without affecting the underlying layers.
Solution Approach 2:
The patent changes the chemical composition and physical state of the silicon-and-germanium-containing material through oxidation, transforming it into a state that is more susceptible to selective etching. By altering the material parameters (oxidation state, surface chemistry) before etching, the process achieves both high etching speed and high selectivity, resolving the technical contradiction between these two parameters.
2Manufacturing precision
If wet etching is used to selectively remove material, then etching selectivity is improved, but penetration capability deteriorates in constrained trenches
Solution Approach 1:
The patent replaces wet chemical etching with plasma-based etching for the actual material removal step. Plasma etching uses reactive species in a plasma state that can physically and chemically etch material with better directionality and penetration capability into constrained trenches, while maintaining selectivity through the preliminary oxidation step and controlled plasma chemistry.
Solution Approach 2:
The patent employs a composite approach combining oxidation (chemical modification) with plasma etching (physical-chemical removal). The oxidized silicon-and-germanium material forms a distinct layer that responds differently to plasma etching than the underlying material, enabling selective deep etching into constrained trenches while maintaining high selectivity.
3Length of moving object
If local plasma is used to improve trench penetration, then penetration capability is improved, but substrate damage increases due to electric arcs
Solution Approach 1:
The patent performs preliminary oxidation to create a modified surface layer before plasma etching. This pre-modified layer acts as a protective interface that reduces direct plasma interaction with the substrate, minimizing substrate damage from electric arcs while still allowing effective trench penetration through the oxidized layer.
Solution Approach 2:
The oxidized silicon-and-germanium layer serves as an intermediary between the plasma and the substrate. This intermediate layer absorbs and dissipates some of the plasma energy, reducing the harmful effects of electric arcs on the substrate while still allowing the plasma to effectively etch through the trench.
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
The method achieves selective etching of silicon-and-germanium-containing materials with high selectivity, reducing unwanted etching of underlying layers and improving the quality of semiconductor devices.
Implementation Method 1
The contacting may form a passivation material on the substrate
Implementation Method 2
The contacting may selectively etch the first layer of silicon-and-germanium-containing material
Implementation Method 3
The contacting may oxidize at least a portion of the second layer of silicon-and-germanium-containing material
Data Source
AI summary
Exemplary semiconductor processing methods may include providing a first etchant precursor to a processing region of a semiconductor processing chamber. A substrate may be housed within the processing region. A first layer of silicon-and-germanium-containing material, a second layer of silicon-and-germanium-containing material, and a layer of silicon-containing material may be disposed on the substrate. The methods may include providing a passivation precursor to the processing region. The methods may include contacting the substrate with the first etchant precursor and the passivation precursor. The contacting may selectively etch the first layer of silicon-and-germanium-containing material. The contacting may form a passivation material on the substrate.