Bottom Passivation for Selective Lateral Dielectric Etching
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The semiconductor industry faces challenges in achieving precise and selective lateral etching for advanced semiconductor devices like gate-all-around field effect transistors (GAAFETs) due to difficulties in eliminating vertical etching and potential damage to device structures during lateral etching processes.
Innovation Solution
A two-step plasma process involving directional surface functionalization with a halogen-containing plasma followed by an oxygen plasma treatment is used to form a selective bottom passivation layer, which is then cyclically repeated to achieve a thick layer at the bottom while minimizing sidewall coverage, enabling controlled lateral etching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional plasma etching is used to remove dielectric layers, then lateral etching can be achieved, but vertical etching cannot be completely eliminated causing potential damage to device structures
Solution Approach 1:
A passivation layer is formed on the bottom surface of the recess before the lateral etching process. This preliminary protective action prevents vertical etching damage during subsequent dielectric removal, allowing precise lateral etching without harm to underlying device structures.
Solution Approach 2:
The passivation layer acts as an intermediary protective barrier between the plasma etching process and the device structures at the recess bottom. It selectively protects against vertical etching while permitting lateral etching to proceed, thereby resolving the contradiction between achieving lateral etching precision and preventing vertical etching damage.
2Object-affected harmful factors
If a thick passivation layer is formed at the bottom to protect device structures, then vertical etching damage is prevented, but sidewall coverage increases reducing lateral etching effectiveness
Solution Approach 1:
The passivation layer is selectively formed with different thicknesses at different locations: thick at the bottom surface to provide protection, and thin or absent on the sidewalls to maintain lateral etching effectiveness. This localized quality variation resolves the contradiction between protection and etching effectiveness.
Solution Approach 2:
The solution transitions from uniform passivation layer coverage to dimensionally selective coverage, where the passivation layer thickness varies by location (bottom vs. sidewalls). This dimensional differentiation allows simultaneous achievement of bottom protection and sidewall etching efficiency.
3Manufacturing precision
If multiple plasma steps are used to form selective passivation layer, then directional selectivity is improved, but process complexity increases
Solution Approach 1:
The process utilizes changes in plasma parameters (gas composition, power levels, pressure) between different plasma steps to achieve selective passivation layer formation. By modifying physical and chemical parameters rather than adding numerous process steps, directional selectivity is improved while process complexity is managed.
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 method enhances directional selectivity in lateral etching, protecting the underlying structure and allowing precise removal of dielectric layers without damage, thus facilitating the fabrication of complex semiconductor devices.
Implementation Method 1
exposing the substrate to a first plasma including a halogen
Implementation Method 2
exposing the substrate to a first plasma including a halogen, and exposing the substrate to a second plasma including oxygen to form the bottom passivation layer
Implementation Method 3
exposing the substrate to a second plasma including oxygen to form the bottom passivation layer
Implementation Method 4
exposing the substrate to a third plasma including fluorine in the plasma processing chamber to laterally etch the dielectric layer at sidewalls of the recess
Data Source
AI summary
A method of processing a substrate that includes: forming a bottom passivation layer including an oxide over a first portion of a dielectric layer at a bottom of a recess of the substrate, the recess having sidewalls including a second portion of the dielectric layer; and performing a lateral etch to etch the second portion of the dielectric layer, the bottom passivation layer covering the first portion of the dielectric layer during the lateral etch, and where the forming of the bottom passivation layer includes exposing the substrate to a first plasma including a halogen, and exposing the substrate to a second plasma including oxygen to form the bottom passivation layer.