Mask Layer Pre-treatment for Ballistic Electron Beam Etching
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Solution Overview
Problem
The existing dry plasma etching processes using ballistic electron beams often result in line edge roughness (LER) and pattern abnormalities in the mask layer, which can lead to reduced manufacturing yields and poor device performance due to initial exposure to energetic electron beams and atomic halogen species, causing damage and defects in the mask layer.
Innovation Solution
A method involving the pre-treatment of the mask layer with an oxygen-containing, halogen-containing, or noble gas plasma in the absence of bond-breaking excitation, followed by the formation of a protective layer or exposure to an electron beam without atomic halogen species, to reduce LER and enhance etch selectivity during the etching process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a dry plasma etching process using ballistic electron beams is used to etch thin films, then etching speed and anisotropy are improved, but line edge roughness and pattern abnormalities occur in the mask layer
Solution Approach 1:
The patent applies preliminary action by treating the mask layer with oxygen plasma or electron beam exposure before the main etching process. This pre-treatment modifies the mask layer surface to make it more resistant to damage from the subsequent ballistic electron beam etching, thereby preventing line edge roughness while maintaining high etching speed.
Solution Approach 2:
The patent implements beforehand cushioning by forming a protective layer on the mask layer prior to etching. This protective layer acts as a cushion that absorbs the damaging effects of energetic electron beams and reactive species, protecting the mask pattern from degradation while allowing fast anisotropic etching to proceed.
2Reliability
If ballistic electron beams and atomic halogen species are used during etching, then etch selectivity is improved, but damage and defects occur in the mask layer
Solution Approach 1:
The patent applies preliminary action by pre-treating the mask layer with oxygen plasma or electron beam exposure before the main etching process. This pre-treatment modifies the mask layer surface to make it more resistant to damage from the subsequent ballistic electron beam etching, thereby preventing line edge roughness while maintaining high etching speed.
Solution Approach 2:
The patent introduces an intermediary protective layer between the mask layer and the etching plasma. This protective layer mediates the interaction by being exposed to the ballistic electron beams and reactive species first, thereby protecting the underlying mask layer from damage while allowing the etching process to proceed with high selectivity.
3Device complexity
If no protective measures are taken for the mask layer, then process complexity is reduced, but manufacturing yield decreases due to pattern abnormalities
Solution Approach 1:
The patent applies preliminary action by pre-treating the mask layer with oxygen plasma or electron beam exposure before the main etching process. This pre-treatment modifies the mask layer surface to make it more resistant to damage from the subsequent ballistic electron beam etching, thereby preventing line edge roughness while maintaining high etching speed.
Solution Approach 2:
The patent employs a disposable protective layer that is intentionally designed to be consumed or modified during the etching process. This protective layer is cheaper and simpler to apply than complex mask protection systems, and its temporary nature allows it to effectively absorb damage without requiring recovery or regeneration.
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 proposed method effectively reduces line edge roughness and pattern abnormalities, improving etch selectivity and manufacturing yields by creating a resilient mask layer that minimizes damage from energetic electrons and halogen species, thereby enhancing the overall etching process.
Implementation Method 1
forming plasma in a plasma processing system from a process gas
Implementation Method 2
electrons heated via the transfer of radio frequency (RF) power
Implementation Method 3
coupling direct current (DC) power to an electrode in the plasma processing system to form an electron beam within the plasma processing system
Implementation Method 4
treating the mask layer with an oxygen-containing, halogen-containing, or noble gas plasma
Implementation Method 5
selected surfaces of the substrate are etched by the plasma
Implementation Method 6
create reactant specie(s) suitable for the exposed surface etch chemistry
Data Source
AI summary
A method of pre-treating a mask layer prior to etching an underlying thin film is described. A thin film, such as a dielectric film, is etched using plasma that is enhanced with a ballistic electron beam. In order to reduce the loss of pattern definition, such as line edge roughness effects, the mask layer is treated with a hydrocarbon chemistry or hydrofluorocarbon chemistry or fluorocarbon chemistry or combination of two or more thereof prior to proceeding with the etching process.