Atomic Layer Etching Selectivity via Surface Conversion Etch Stop
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Solution Overview
Problem
In semiconductor fabrication, achieving high etch selectivity is challenging as device geometries shrink, making it difficult to effectively etch desired materials without etching other materials.
Innovation Solution
A method involving a substrate with a first material covering a second material, where a first process gas modifies the first material, a second process gas removes the modified first material, and a third process gas converts the exposed second material surface into a converted layer that is less reactive with the etching gases than the first and second materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional etching processes are used to remove the first material, then etching speed is maintained, but etch selectivity deteriorates causing unwanted etching of the second material
Solution Approach 1:
The patent applies preliminary action by converting the surface of the second material to a different material state before the etching process begins. This pre-conversion creates an etch-stop layer that prevents unwanted etching of the second material, allowing the etching process to proceed with high selectivity without sacrificing etching speed of the first material.
Solution Approach 2:
The patent implements local quality by creating a converted layer only on the surface of the second material where it is exposed, while leaving the bulk material and other regions unchanged. This localized conversion provides selective protection exactly where needed, maintaining etch selectivity without affecting the overall etching process efficiency.
2Reliability
If the second material surface is converted to a less reactive layer, then protection against etching is improved, but process complexity increases due to additional process gases and steps
Solution Approach 1:
The patent applies universality by designing the conversion process to serve multiple functions simultaneously: it creates an etch-stop layer for selectivity, prepares the surface for subsequent processing, and can be integrated with existing etching workflows. The same process gas flow infrastructure is used for both conversion and etching operations, reducing the need for entirely separate process equipment.
Solution Approach 2:
The patent implements continuity of useful action by making the conversion process continuous with the etching process. The conversion occurs on exposed surfaces as they become available during the etching of the first material, and the converted layer remains in place to protect the second material throughout the subsequent etching steps, maintaining protection effectiveness without requiring intermittent re-application.
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 enhances etch selectivity by creating an etch stop layer that protects the underlying material from etching, allowing for precise removal of the first material while minimizing the etching of the second material.
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.