Selective SiGe Etching Using Nitrogen Radical Pre-Treatment
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Solution Overview
Problem
Current methods for selective etching of SiGe, Si, and Ge in semiconductor substrates are unsatisfactory, often resulting in damage or permanent modification of layers, and struggle with achieving desired selectivity between these materials.
Innovation Solution
A pre-treatment process using a nitrogen plasma with removed ions, applying nitrogen radicals to the substrate, followed by selective etching with gas phase chemistry, allows for controlled etching of SiGe relative to Ge or Si, and vice versa, while maintaining protection of higher Ge content layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional etching methods are used to achieve selective etching of SiGe, Si, and Ge, then etching selectivity is improved, but damage or permanent modification of layers occurs
Solution Approach 1:
A pre-treatment step is performed before the main etching process to modify the surface properties of specific layers. This preliminary action creates a protective modification on Ge layers that prevents damage during subsequent selective etching, while allowing SiGe and Si layers to be etched with high selectivity.
Solution Approach 2:
The patent introduces an intermediary treatment process that modifies the material properties of Ge layers without permanently damaging them. This intermediary step acts as a mediator between the etching process and the Ge layers, enabling selective etching of other materials while protecting Ge from damage.
2Manufacturing precision
If selective etching is performed without pre-treatment, then processing simplicity is maintained, but desired selectivity between materials cannot be achieved
Solution Approach 1:
The pre-treatment step is introduced as a necessary preliminary action that enables high selectivity in the subsequent etching process. By modifying the Ge layers beforehand, the etching process can achieve desired selectivity between SiGe, Si, and Ge materials.
3Productivity
If ions are present in the plasma during treatment, then etching speed is improved, but damage to sensitive layers increases
Solution Approach 1:
The patent extracts or removes ions from the plasma before the treatment step, retaining only the radical components. This extraction of harmful ions while preserving useful radicals enables fast etching speeds without the damaging effects that would otherwise occur to sensitive Ge layers.
Solution Approach 2:
The patent converts the potentially harmful plasma into a beneficial treatment by removing ions while retaining radicals. The resulting ion-free plasma provides the benefits of plasma treatment (such as surface modification and etching capability) without the harmful damaging effects of ions on sensitive Ge layers.
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 selective etching with reduced damage, achieving desired selectivity and protecting higher Ge content layers, allowing for precise processing in semiconductor architectures, including indent, channel release, and channel trim processes.
Implementation Method 1
The treatment is performed with a plasma containing nitrogen, in which nitrogen ions of the plasma have been removed so that the treatment is performed with a plasma of nitrogen radicals
Implementation Method 2
the treatment is performed with a plasma of nitrogen radicals
Implementation Method 3
followed by selective etching with gas phase chemistry
Implementation Method 4
the treated surface (such as a nitride surface) can be removed during the etching and optional heat treatment
Data Source
AI summary
Etching is selectively performed and selectively is modified using a treatment or pre-treatment with nitrogen radicals, prior to etching. Etching is performed with a gas phase chemistry etch. Different selectivities can also be provided in different processes or different regions (or different devices or different locations) of a substrate by the selective use and non-use of the treatment.