Localized EUV Pellicle Glue Removal Without Capping Layer Damage
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Solution Overview
Problem
Existing EUV mask cleaning systems are unable to completely remove pellicle glue from EUV masks, leading to potential performance issues in subsequent lithography processes due to residue left on the LTEM substrate, as they cannot use oxidized chemicals that could damage the Ruthenium-containing capping layer.
Innovation Solution
A localized EUV mask cleaning method and system that uses targeted cleaning chemicals, such as sulfuric acid-hydrogen peroxide mixtures or Tetrahydrofuran, applied through a pressurized system with a multi-tube design to specifically target and remove the glue without damaging the Ruthenium capping layer, and optionally employs plasma or focused laser beams to react with the glue, ensuring effective removal while minimizing contamination of other areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional cleaning chemicals are used on the entire EUV mask, then the Ruthenium-containing capping layer is protected from damage, but the pellicle glue cannot be completely removed
Solution Approach 1:
The patent applies different cleaning chemicals to different regions of the EUV mask. Specifically, oxidized cleaning chemicals are applied only to the region where pellicle glue is located, while the rest of the mask receives protective treatment. This localized approach allows aggressive glue removal without exposing the Ruthenium-containing capping layer to damaging oxidized chemicals throughout the entire mask surface.
Solution Approach 2:
The cleaning process is divided into distinct segments: a glue-removal portion targeting the pellicle glue region and a protective portion covering the rest of the mask. The system segments the application area and chemical types, ensuring that the Ruthenium-containing capping layer is protected while the glue is effectively removed from its specific location.
2Manufacturing precision
If oxidized cleaning chemicals are applied to remove glue completely, then glue removal effectiveness is improved, but the Ruthenium-containing capping layer is damaged
Solution Approach 1:
The patent implements spatial differentiation in chemical application by directing oxidized cleaning chemicals exclusively at the pellicle glue region while shielding or excluding the Ruthenium-containing capping layer from exposure. This localized chemical treatment achieves complete glue removal without inflicting damage on the sensitive capping layer materials.
Solution Approach 2:
The cleaning system segments the mask surface into a treatment zone (where glue is removed using oxidized chemicals) and a protected zone (where the Ruthenium-containing capping layer is shielded from oxidized chemicals). This segmentation allows the use of aggressive cleaning agents without compromising the integrity of the capping layer.
3Ease of operation
If the pellicle is removed for cleaning, then access to glue is achieved, but glue residue remains on the LTEM substrate
Solution Approach 1:
The patent changes the chemical parameters of the cleaning process by introducing oxidized cleaning chemicals specifically for glue removal. After pellicle removal exposes the glue on the LTEM substrate, the system applies these enhanced chemicals to completely eliminate glue residue, thereby improving upon conventional cleaning methods that leave residue behind.
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 method effectively removes EUV pellicle glue from the EUV mask without damaging the Ruthenium-containing capping layer, ensuring improved lithography performance by eliminating glue residue and allowing the use of stronger cleaning agents, while maintaining compatibility with existing process flows.
Implementation Method 1
a cleaning chemical is injected onto the glue, the cleaning chemical reacting with the glue to produce a waste chemical
Implementation Method 2
a pressurized system with a multi-tube design... a first tube through which a cleaning chemical is injected under a positive pressure, and a second tube through which a waste chemical is removed under a negative pressure
Implementation Method 3
optionally employs plasma or focused laser beams to react with the glue
Implementation Method 4
optionally employs plasma or focused laser beams to react with the glue
Data Source
AI summary
An extreme ultraviolet (EUV) mask is received. The EUV mask has an EUV pellicle disposed thereover. The EUV pellicle is coupled to the EUV mask at least in part via glue that is disposed on the EUV mask. The EUV pellicle is removed, thereby exposing the glue. A localized glue-removal process is performed by targeting a region of the EUV mask on which the glue is disposed. The localized glue-removal process is performed without affecting other regions of the EUV mask that do not have the glue disposed thereon. The localized glue-removal process may include injecting a cleaning chemical onto the glue and removing a waste chemical produced by the cleaning chemical and the glue. The localized glue-removal process may also include a plasma process that applies plasma to the glue. The localized glue-removal process may further include a laser process that shoots a focused laser beam at the glue.