Phase-Shifting EUV Mask Layout for Multi-Exposure Lithography
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Solution Overview
Problem
Existing EUV masks and manufacturing methods face challenges in detecting and repairing microscopic defects, which affect the printability of patterns and are difficult to inspect, leading to complexity in processing and manufacturing semiconductor integrated circuits.
Innovation Solution
A phase-shifting EUV mask design with a multilayer reflective coating and a patterned second reflective layer, utilizing alternating materials to achieve a 180° phase shift and minimize radiation energy loss, along with a multiple exposure process to form a patterned resist layer, enhancing imaging quality and throughput.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If EUV lithography processes are implemented to meet size constraints, then resolution is improved, but manufacturing complexity increases
Solution Approach 1:
The mask is divided into multiple identical pattern areas, where each area can independently form the required pattern. This segmentation allows the manufacturing process to target and repair specific defective areas without affecting the entire mask, thereby reducing manufacturing complexity while maintaining high resolution
Solution Approach 2:
The invention changes the parameter of mask structure by adding a second reflective layer with alternating materials designed to produce a 180-degree phase shift. This parameter change improves resolution through better pattern definition while the modular design keeps manufacturing complexity manageable
2Manufacturing precision
If reflective masks are used to transfer patterns, then imaging quality is improved, but radiation energy loss increases
Solution Approach 1:
The mask uses a composite structure with a reflective multilayer coating consisting of alternating layers of materials with different optical properties. This composite structure is designed to reflect EUV radiation efficiently while maintaining the required phase shift, thereby improving imaging quality and reducing radiation energy loss simultaneously
3Productivity
If multiple exposure processes are used to form patterns, then throughput is increased, but manufacturing precision requirements increase
Solution Approach 1:
The mask contains multiple identical pattern areas that can be used in sequence during multiple exposure processes. Each area is independently manufacturable and inspectable, allowing the system to maintain high throughput through parallel processing while reducing the precision burden on any single exposure step
Solution Approach 2:
The mask is pre-designed with multiple identical pattern areas and phase-shift structures that are manufactured and inspected before use. This preliminary action ensures that when multiple exposures are performed, the precision requirements are already met, allowing high throughput without compromising pattern formation precision
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 defects and errors in the lithography process, resulting in higher resolution and reduced production time.
Implementation Method 1
EUV lithography uses a reflective mask (also referred to as a reticle) to transfer a pattern of a layer of an integrated circuit device to a wafer. A reflective mask typically includes a reflective multilayer coating (multi-layered mirror stack) disposed on a substrate.
Implementation Method 2
A phase-shifting EUV mask design with a multilayer reflective coating and a patterned second reflective layer, utilizing alternating materials to achieve a 180° phase shift
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.