Pellicle with Light Shielding and Grating Patterns for EUV Mask Protection
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Solution Overview
Problem
Highly integrated semiconductor devices require exposure devices using extreme ultra violet (EUV) light, but reflective masks are prone to contamination by particles during the exposure process, leading to errors and instability in the exposure process.
Innovation Solution
A pellicle for reflective masks is designed, comprising a pellicle body with a light shielding pattern and a grating pattern, which is placed over the reflective mask to protect it from particle contamination, featuring a pellicle frame that supports the pellicle body and includes a central region and a peripheral region with the light shielding pattern formed on the peripheral region to block EUV and DUV light, and a grating pattern to suppress the influence of reflected DUV light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a reflective mask is used for EUV light exposure, then the resolution and exposure precision are improved, but the mask becomes susceptible to particle contamination during the exposure process
Solution Approach 1:
A pellicle is introduced as an intermediary component between the EUV light source and the reflective mask. The pellicle serves as a protective barrier that prevents particle contamination of the mask while allowing EUV light to pass through, thus resolving the contradiction between maintaining exposure precision and preventing mask contamination
Solution Approach 2:
The pellicle is designed as a thin film structure that provides protective functionality without significantly obstructing the EUV light. This thin film approach allows the mask to maintain its optical performance while being protected from particles in the exposure environment
2Reliability
If a pellicle is added to protect the reflective mask, then particle contamination is reduced, but the device complexity increases
Solution Approach 1:
The pellicle is implemented as a thin film structure that provides effective particle protection while minimizing optical interference. The thin film design allows the protective function to be added with minimal impact on the overall device complexity and optical performance
Solution Approach 2:
The pellicle structure is designed to perform multiple functions simultaneously: it protects the mask from particles, maintains optical transmission for EUV light, and can be integrated with the mask support structure. This multi-functionality reduces the need for separate protective components, thereby limiting the increase in device complexity
3Reliability
If the pellicle body is made thicker to improve protection, then particle barrier capability is enhanced, but the transmission rate of EUV light decreases
Solution Approach 1:
The thickness of the pellicle is optimized to a specific parameter range that balances particle protection capability with EUV light transmission. By carefully controlling the thickness parameter, the pellicle provides adequate protection while maintaining high light transmission rate
Solution Approach 2:
The pellicle is designed as an ultra-thin film structure that provides effective particle barrier functionality without significantly absorbing EUV light. The thin film design allows the protective function to be achieved with minimal optical loss
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 pellicle effectively prevents particle contamination, ensuring a stable and accurate exposure process by maintaining a high transmission rate of EUV light and reducing reflection errors, thereby enhancing the reliability of EUV light exposure devices.
Implementation Method 1
a light shielding pattern formed on a peripheral region of the pellicle body corresponding to a black border region of the reflective mask
Implementation Method 2
a grating pattern formed on the light shielding pattern corresponding to the black border region, wherein the grating pattern may suppress the influence of reflected light deviating from a wavelength range of the EUV light
Implementation Method 3
maintaining a high transmission rate of EUV light
Data Source
AI summary
A pellicle for a reflective mask including a pellicle body, a light shielding pattern, a grating pattern, and a pellicle frame. The pellicle body includes a central region and a peripheral region, wherein the peripheral region surrounds the central region. The light shielding pattern is formed on the peripheral region of the pellicle body; the grating pattern is formed on the light shielding pattern, and the pellicle frame is located under the peripheral region of the pellicle body, and the pellicle frame is configured to support the pellicle body.