SiGe Selective Etching via Oxidation for Germanium Contrast
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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, particularly in gate-all-around (GAA) transistors, leading to undesirable etching of epitaxial silicon-and-germanium-containing material.
Innovation Solution
A method involving selective oxidation of silicon-and-germanium-containing materials with varying germanium concentrations, followed by a controlled etching process, where materials with higher germanium concentrations are preferentially oxidized, making them more resistant to etching, allowing selective removal of materials with lower germanium concentrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional etching processes are used, then etching speed is maintained, but selectivity between different germanium concentration materials deteriorates
Solution Approach 1:
The patent applies preliminary oxidation to the silicon-germanium-containing material before etching. By oxidizing the material in advance, a silicon oxide layer is formed that provides selective protection during subsequent etching processes. This preliminary action enables high selectivity (greater than 40:1) between materials with different germanium concentrations while maintaining acceptable etching speeds.
Solution Approach 2:
The patent changes the chemical state of the silicon-germanium-containing material by controlling oxidation conditions. By adjusting oxidation parameters (temperature, time, atmosphere), the material is transformed into an oxidized state that exhibits different etching resistance. This parameter change enables selective etching based on original germanium concentration while preserving both selectivity and productivity.
2Manufacturing precision
If wet etching is used, then etching uniformity is improved, but penetration capability into constrained trenches deteriorates
Solution Approach 1:
The patent introduces oxidation as an intermediary process between material deposition and etching. This intermediary step creates a protective oxide layer that modifies the etching behavior, enabling uniform etching across complex three-dimensional structures including constrained trenches. The oxidation intermediary allows wet etching to achieve both uniformity and penetration by protecting sidewalls while enabling anisotropic etching into trenches.
3Length of moving object
If dry etching with local plasma is used, then trench penetration is improved, but substrate damage through electric arcs worsens
Solution Approach 1:
The patent applies preliminary oxidation before dry etching with local plasma. This preliminary action creates a protective oxide layer that prevents direct plasma contact with the substrate, thereby eliminating electric arc damage while maintaining the trench penetration capability of local plasma etching. The oxidation step acts as a protective barrier that enables aggressive plasma etching without substrate harm.
4Manufacturing precision
If selective oxidation is applied, then etching selectivity is improved, but process complexity worsens
Solution Approach 1:
The patent merges the oxidation and etching processes into a closely integrated sequence where oxidation is performed immediately before etching in the same fabrication flow. By combining these steps and optimizing their parameters, the process achieves greater than 40:1 selectivity while minimizing the overall complexity increase. The merged approach allows selective etching without requiring entirely separate process modules.
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 with a selectivity of greater than 40:1, ensuring precise removal of targeted silicon-and-germanium-containing materials while preserving other materials, thereby improving the quality of semiconductor devices.
Implementation Method 1
The contacting may remove the native oxide from the first layer of silicon-and-germanium-containing material and the second layer of silicon-and-germanium-containing material
Implementation Method 2
The contacting may oxidize at least a portion of the second layer of silicon-and-germanium-containing material
Implementation Method 3
The contacting may selectively etch the first layer of silicon-and-germanium-containing material
Data Source
AI summary
Exemplary semiconductor processing methods may include providing a pre-treatment precursor to a processing region of a semiconductor processing chamber. A first layer of silicon-and-germanium-containing material and a second layer of silicon-and-germanium-containing material may be disposed on a substrate housed within the processing region. A native oxide may be present on the first layer and the second layer. The methods may include contacting the substrate with the pre-treatment precursor to remove the native oxide. The methods may include providing an oxygen-containing precursor to the processing region. The methods may include contacting the substrate with the oxygen-containing precursor to oxidize at least a portion of the second layer. The methods may include providing an etchant precursor to the processing region. The methods may include contacting the substrate with the etchant precursor to selectively etch the first layer of silicon-and-germanium-containing material.