EUV Mask Defect Avoidance Pattern for Blister Prevention
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Solution Overview
Problem
The existing EUV lithography process faces challenges with blister defects due to hydrogen accumulation between the capping layer and the absorption layer, leading to reduced reliability and durability of EUV masks, and increased resource waste and manufacturing time.
Innovation Solution
The introduction of a defect avoidance pattern (DAP) in the absorption layer of the EUV mask, which exposes a beam calibration point (BCP) to prevent hydrogen accumulation and minimize blister defects, thereby enhancing the mask's reliability and durability, and optimizing the manufacturing process by reducing additional processes and turn-around time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional EUV mask structure is used, then the mask can be manufactured with standard processes, but hydrogen accumulation causes blister defects that reduce reliability and durability
Solution Approach 1:
The patent introduces a beam calibration point (BCP) opening in the absorption layer before the mask is fully assembled and used. This preliminary opening prevents hydrogen accumulation from occurring in the first place by providing an escape path, thereby preventing blister defects before they can form and compromise mask reliability.
Solution Approach 2:
The patent creates a localized opening (BCP) specifically in the non-transfer region of the absorption layer, rather than modifying the entire mask structure. This localized modification allows hydrogen to escape from the critical area without affecting the overall mask integrity or the transfer region functionality, thus resolving the blister defect issue while maintaining mask reliability.
2Reliability
If additional defect avoidance patterns are added to the mask, then blister defects are prevented, but the manufacturing process becomes more complex and time-consuming
Solution Approach 1:
The patent combines the beam calibration point opening with the existing absorption layer fabrication process. By integrating the BCP opening creation into the standard absorption layer formation steps, the patent avoids adding separate complex manufacturing processes while still achieving the defect prevention function, thus improving durability without significantly increasing process complexity.
Solution Approach 2:
The BCP opening structure serves multiple functions: it prevents hydrogen accumulation to avoid blister defects, and it also facilitates beam calibration during mask manufacturing. This multi-functional design means that a single structural feature provides both defect prevention and process calibration benefits, reducing the need for additional separate components or processes.
3Manufacturing precision
If the absorption layer is made completely opaque to prevent light transmission, then pattern transfer is achieved, but hydrogen has no escape path leading to blister defects
Solution Approach 1:
The patent segments the absorption layer into two functional regions: a transfer region with full absorption for accurate pattern transfer, and a non-transfer region containing the BCP opening that allows hydrogen escape. This segmentation maintains the necessary opacity for pattern transfer precision while creating a localized pathway for hydrogen relief, thus resolving the contradiction between manufacturing precision and reliability.
Solution Approach 2:
The patent applies different properties to different parts of the absorption layer: the transfer region maintains complete opacity for precise pattern transfer, while the non-transfer region contains a localized opening for hydrogen escape. This local differentiation allows the mask to simultaneously achieve high pattern transfer accuracy and improved reliability by preventing hydrogen accumulation.
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 DAP effectively prevents blister defects by exposing the BCP, improving the EUV mask's reliability and durability, and optimizing the manufacturing process by minimizing resource waste and reducing manufacturing time.
Implementation Method 1
a reflective multilayer disposed on the substrate, wherein the reflective multilayer comprises a plurality of each of two types of material layers and including tens of two types of material layers that are alternately stacked on each other
Implementation Method 2
an absorption layer disposed on the reflective multilayer, wherein the absorption layer comprises a central transfer region and a non-transfer region
Data Source
AI summary
The present disclosure describes an extreme ultra-violet (EUV) mask having improved reliability and durability and a manufacturing method thereof. The extreme ultra-violet mask includes a substrate, a reflective multilayer disposed on the substrate and comprising a plurality of each of two types of material layers alternately stacked on each other, and an absorption layer disposed on the reflective multilayer, wherein the absorption layer comprises a central transfer region and a non-transfer region, wherein an opening through the non-transfer region of the absorption layer forms a defect avoidance pattern that exposes a beam calibration point of the reflective multilayer.