Phase-Shifting EUV Mask Defect Compensation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing EUV lithography masks face challenges in defect inspection and repair due to microscopic defects in substrates and reflective multilayers, which affect printability and are difficult to detect and correct.
Innovation Solution
A phase-shifting EUV mask design with a low thermal expansion substrate, a reflective multilayer, and a buffer layer, combined with a patterned second reflective layer, is used to enhance reflectivity and reduce defects, allowing for improved imaging quality and throughput by using multiple exposures with reduced exposure doses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If EUV lithography uses a reflective mask with multilayer coating to achieve high resolution for 7-nm technology nodes, then imaging resolution is improved, but mask defects become more difficult to detect and repair
Solution Approach 1:
The patent applies preliminary action by incorporating a buffer layer during mask fabrication that prevents defect formation before they occur. The buffer layer is designed to compensate for potential defects in the reflective multilayer coating, addressing defect issues proactively rather than detecting and repairing them after formation. This approach improves defect detection capability while maintaining the high resolution imaging capability of the reflective mask.
2Manufacturing precision
If multiple exposures with reduced exposure doses are used to improve imaging quality, then imaging quality is improved, but processing time increases
Solution Approach 1:
The patent applies parameter changes by optimizing the buffer layer thickness and composition to achieve the desired imaging quality with fewer exposures. By carefully controlling the buffer layer parameters (thickness, material composition), the system can achieve improved imaging quality while minimizing the number of exposure steps required, thus reducing the time penalty associated with multiple exposures.
3Reliability
If a buffer layer is added to the mask structure to reduce defects, then defect resistance is improved, but mask structure complexity increases
Solution Approach 1:
The patent applies local quality by adding the buffer layer only in specific regions where defect compensation is most needed, rather than uniformly throughout the entire mask structure. The buffer layer is strategically positioned to address critical defect areas in the reflective multilayer coating, providing defect resistance where it matters most while minimizing the overall increase in mask structure 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
The solution improves imaging quality, reduces radiation energy loss, and increases throughput by minimizing the impact of mask defects and other errors, resulting in higher yield and reduced defects in semiconductor device manufacturing.
Implementation Method 1
A phase-shifting EUV mask design with a low thermal expansion substrate, a reflective multilayer, and a buffer layer, combined with a patterned second reflective layer, is used to enhance reflectivity and reduce defects
Data Source
AI summary
An extreme ultraviolet lithography (EUVL) method includes providing at least two phase-shifting mask areas having a same pattern. A resist layer is formed over a substrate. An optimum exposure dose of the resist layer is determined, and a latent image is formed on a same area of the resist layer by a multiple exposure process. The multiple exposure process includes a plurality of exposure processes and each of the plurality of exposure processes uses a different phase-shifting mask area from the at least two phase-shifting mask areas having a same pattern.