EUV Mask Critical Dimension Control via Oxygen Nitrogen Plasma
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing EUV lithography mask fabrication processes face challenges in controlling critical dimensions (CD) and removing debris particles due to high Van der Waals forces and hydrophobic surface properties, leading to potential fabrication errors and mask scrap.
Innovation Solution
The proposed solution involves a method for making EUV lithography masks that includes patterning an absorber layer to form trenches, treating the mask with oxygen plasma to enhance oxide layer growth and reduce CD, and subsequently treating it with nitrogen plasma to protect the capping layer and adjust the trench width to meet target CD specifications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the absorber layer is patterned to form trenches with narrow critical dimensions, then the device functional density increases, but the manufacturing precision deteriorates due to high Van der Waals forces causing adsorption of debris particles and etch bias
Solution Approach 1:
The patent applies oxygen plasma treatment to oxidize the absorber layer surface, changing its chemical composition and surface properties. This oxidation reduces the Van der Waals forces and hydrophobicity, thereby improving particle removal capability and critical dimension control during subsequent cleaning processes
Solution Approach 2:
Oxygen plasma is used as a strong oxidizing environment to accelerate the formation of oxide layers on the absorber layer surface. This enhanced oxidation modifies the surface energy and reduces adhesion of debris particles, addressing the manufacturing precision issue while maintaining high device functional density
2Ease of manufacture
If the absorber layer surface is left with hydrophobic properties, then the fabrication process is simpler, but particle removal during cleaning is hindered
Solution Approach 1:
The patent changes the surface energy parameters of the absorber layer through oxygen plasma treatment. The plasma oxidation converts the hydrophobic surface to a more hydrophilic state, reducing the adhesion strength of organic debris particles and enabling effective removal during cleaning without complicating the fabrication process
Solution Approach 2:
Oxygen plasma provides a reactive environment that temporarily modifies the surface properties during treatment. The plasma state allows for controlled oxidation that reduces particle adhesion, and the effect is maintained after returning to ambient conditions, effectively addressing particle removal issues
3Productivity
If the etch bias is kept at 2-3 nm, then the patterning process is faster, but the critical dimension specification is not met due to narrow CD requirements at lower nodes
Solution Approach 1:
The patent applies oxygen plasma treatment as a preliminary step before final patterning and cleaning. This pre-treatment modifies the absorber layer surface to reduce subsequent etch bias and improve particle removal, allowing the patterning process to meet narrow critical dimension specifications while maintaining efficient processing speed
Solution Approach 2:
By changing the surface oxidation state through plasma treatment, the patent modifies the etch characteristics of the absorber layer. This parameter change reduces the etch bias from 2-3 nm to a lower value, enabling compliance with narrow critical dimension specifications at lower technology nodes without sacrificing patterning productivity
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 effectively controls critical dimensions and improves particle removal during cleaning, enhancing the accuracy and reusability of EUV lithography masks while reducing the risk of fabrication errors.
Implementation Method 1
treating the mask with oxygen plasma to enhance oxide layer growth
Implementation Method 2
enhance oxide layer growth on the first and second sidewalls
Implementation Method 3
treating the mask with nitrogen plasma to protect the capping layer
Implementation Method 4
The absorber layer may exhibit high Van der Waals forces, resulting from a high number of metal atoms, that cause adsorption of debris particles on a surface thereof
Data Source
AI summary
The present disclosure describes a method of patterning a semiconductor wafer using extreme ultraviolet lithography (EUVL). The method includes receiving an EUVL mask that includes a substrate having a low temperature expansion material, a reflective multilayer over the substrate, a capping layer over the reflective multilayer, and an absorber layer over the capping layer. The method further includes patterning the absorber layer to form a trench on the EUVL mask, wherein the trench has a first width above a target width. The method further includes treating the EUVL mask with oxygen plasma to reduce the trench to a second width, wherein the second width is below the target width. The method may also include treating the EUVL mask with nitrogen plasma to protect the capping layer, wherein the treating of the EUVL mask with the nitrogen plasma expands the trench to a third width at the target width.