Atomic Layer Etching Selectivity Using Surface Conversion Layers
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Solution Overview
Problem
Existing atomic layer etching processes lack high selectivity in etching one material without etching adjacent materials, particularly in semiconductor fabrication where device geometries are becoming smaller, leading to undesired etching of underlying layers.
Innovation Solution
A method involving the use of a first process gas to modify a layer, followed by a second gas to remove the modified layer, and a third gas to convert the exposed surface to a less reactive etch stop layer, ensuring minimal etching of the underlying material, with optional further modifications and removals using fourth and fifth gases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional atomic layer etching processes are used to etch desired materials, then etching of the target material is achieved, but undesired etching of adjacent underlying layers occurs due to insufficient selectivity
Solution Approach 1:
The patent applies preliminary action by converting the surface of the underlying second material to a converted layer with different etch selectivity characteristics before the main etching process completes. This pre-conversion creates a protective barrier that prevents undesired etching of the underlying layer while allowing controlled etching of the first material. The conversion step is performed in advance during the etching sequence, establishing the selective etching capability before it is needed.
Solution Approach 2:
The patent implements local quality by creating a converted layer specifically on the surface of the underlying second material, giving it different chemical properties than the bulk material or the first material. This localized conversion ensures that only the exposed surface of the underlying layer has the protective characteristic, while the rest of the structure maintains its original properties. The converted layer provides localized protection exactly where needed at the interface between materials.
2Manufacturing precision
If multiple process gases are used to achieve selective etching, then etch selectivity is improved, but process complexity increases
Solution Approach 1:
The patent applies universality by using process gases that can perform multiple functions within the atomic layer etching sequence. The first process gas both modifies the first material for etching and can contribute to the conversion of the underlying layer. The second process gas removes the modified layer while also potentially participating in the conversion process. This multi-functionality reduces the need for additional specialized gases, maintaining selectivity while limiting the increase in process complexity.
Solution Approach 2:
The patent implements continuity of useful action by designing the process gas sequence where each gas contributes to multiple objectives throughout the etching cycle. The conversion process occurs continuously during the etching sequence rather than as a separate discrete step, allowing the useful action of material removal and surface conversion to occur simultaneously. This continuous approach integrates the selectivity-enhancing conversion step into the existing etching process flow without adding significant complexity.
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
Achieves high etch selectivity, allowing precise etching of targeted materials while minimizing etching of adjacent layers, thereby improving semiconductor fabrication precision.
Implementation Method 1
modifying a layer of the first material by flowing a first process gas onto the substrate and thereby creating a modified layer of the first material
Implementation Method 2
removing the modified layer of the first material by flowing a second process gas onto the substrate
Implementation Method 3
converting, when the surface of the second material is uncovered via removal of the modified layer, the surface to a converted layer of the second material by flowing a third process gas onto the substrate
Data Source
AI summary
Apparatuses and methods are provided. Some methods may include providing a substrate to a processing chamber, the substrate having a first material adjacent to and covering a surface of a second material, modifying a layer of the first material by flowing a first process gas onto the substrate and thereby creating a modified layer of the first material, removing the modified layer of the first material by flowing a second process gas onto the substrate, and converting, when the surface of the second material is uncovered via removal of the modified layer, the surface to a converted layer of the second material by flowing a third process gas onto the substrate, in which the first and second process gases are less reactive with the converted layer than with the first material and the second material.