Lithography Pellicle Assembly Scanning for In-Situ Particle Detection
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Solution Overview
Problem
The challenge in EUV lithography is the formation of reticle defects due to particles from the vacuum environment of the EUV scanner chamber, which leads to pattern failure, and the use of pellicles introduces inner on-pellicle defects (IOPDs) that reduce EUV power and increase cycle time, with current inspection methods being inefficient and costly.
Innovation Solution
A method for in-situ scanning of the pellicle using optical imagers mounted to the mask stage during mounting, allowing real-time detection and removal of particles on both the pellicle and mask surfaces, reducing tool downtime and improving yield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pellicles are used to prevent reticle defects from particles, then reticle reliability is improved, but inner on-pellicle defects are introduced that reduce EUV power and increase cycle time
Solution Approach 1:
The system performs preliminary scanning and detection of particles on the reticle and pellicle surfaces before final mounting. By detecting and removing particles in advance using optical scanners and ion guns, the system prevents inner on-pellicle defects that would otherwise reduce EUV power and increase cycle time, thus maintaining high productivity while ensuring reticle reliability
2Measurement precision
If current inspection methods are used to detect particles, then particle detection is achieved, but the process is inefficient and costly
Solution Approach 1:
The system replaces traditional mechanical inspection methods with optical scanning technology. Optical scanners mounted on the mask stage perform non-contact, real-time detection of particles on the reticle and pellicle surfaces during mounting operations, significantly improving inspection efficiency while maintaining high detection precision and reducing costs
3Loss of time
If in-situ scanning is performed during mounting, then real-time particle detection is achieved, but device complexity increases
Solution Approach 1:
The system merges the particle detection function with the existing mounting system by mounting optical scanners on the mask stage. This integration allows real-time particle detection during mounting operations without requiring separate inspection equipment, thus minimizing tool downtime while avoiding excessive increase in device complexity
Solution Approach 2:
The mask stage is designed to serve multiple functions: it not only positions and mounts the reticle and pellicle but also carries optical scanners for real-time particle detection. This multi-functionality reduces the need for additional dedicated inspection equipment, balancing the trade-off between real-time detection capability and system complexity
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 identifies and removes particles before final mounting, preventing pattern failures and maintaining EUV power, thereby enhancing productivity and reducing yield loss.
Implementation Method 1
determining whether a defect level of the pellicle is less than a selected value by scanning the pellicle by a first optical detector
Data Source
AI summary
A method includes: placing a mask on a mask stage; placing a pellicle assembly on a pellicle stage, the pellicle assembly including a pellicle; determining whether a defect level of the pellicle is less than a selected value by scanning the pellicle by a first optical detector; forming a protected mask assembly by mounting the pellicle assembly to the mask assembly; and performing semiconductor processing using the protected mask assembly.