Phase-Shifting EUV Mask Exposure for Defect Compensation
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Solution Overview
Problem
Existing EUV lithography masks suffer from defects that are difficult to inspect and repair, affecting printability and requiring improvements in manufacturing processes to meet critical dimension tolerances in semiconductor integrated circuits.
Innovation Solution
A phase-shifting EUV mask design with a multilayer reflective coating and patterned reflective layers, utilizing alternating phase-shift materials to enhance imaging quality, reduce radiation energy loss, and minimize shadow effects, combined with a multiple exposure process to compensate for mask defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a reflective mask with multilayer coating is used in EUV lithography, then pattern transfer capability is improved, but imaging quality deteriorates due to defects in substrate, reflective multilayers, or absorbers
Solution Approach 1:
The patent applies preliminary inspection and repair actions to the reflective mask before the lithography process. Defects in the substrate, reflective multilayers, or absorbers are detected and corrected in advance, preventing imaging quality deterioration while maintaining pattern transfer capability
Solution Approach 2:
The patent introduces an intermediary inspection and repair system between the mask and the lithography process. This intermediary system identifies and corrects defects that would otherwise degrade imaging quality, allowing the reflective mask to maintain both its pattern transfer capability and imaging quality
2Manufacturing precision
If higher resolution lithography processes are implemented to meet size constraints, then manufacturing precision is improved, but device complexity increases
Solution Approach 1:
The patent implements preliminary mask inspection and repair processes before high-resolution lithography. By preparing the mask in advance and correcting defects, the actual lithography process becomes simpler and more reliable, reducing overall processing complexity while maintaining high resolution
Solution Approach 2:
The patent enables the mask to serve itself through automated inspection and repair systems. The mask is autonomously examined and corrected for defects, eliminating the need for complex manual intervention and simplifying the overall high-resolution manufacturing process
3Reliability
If multiple exposure processes are used to compensate for mask defects, then imaging quality is improved, but exposure duration increases
Solution Approach 1:
The patent performs preliminary mask inspection and repair before the exposure process. By correcting defects in advance, the need for multiple exposure processes is eliminated or reduced, maintaining high imaging quality while minimizing exposure duration
Solution Approach 2:
The patent converts the potential harm of mask defects into a benefit by using preliminary repair processes. The defects that would require multiple exposures are corrected in advance, transforming what would be a time-consuming multi-exposure process into a single, efficient exposure while maintaining or improving imaging quality
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
Improves imaging quality, reduces exposure duration, and increases throughput by minimizing radiation energy loss and compensating for mask defects, while maintaining high resolution and contrast.
Implementation Method 1
A reflective mask (also referred to as a reticle) to transfer a pattern of a layer of an integrated circuit device to a wafer
Implementation Method 2
The reflected EUV radiation exposes the photoresist layer, thereby forming a latent pattern in the photoresist layer
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.