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Proceedings Paper

Challenges and solutions ensuring EUVL photomask integrity
Author(s): O. Brux; P. Dreß; H. Schmalfuß; R. Jonckheere; W. Koolen-Hermkens
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Paper Abstract

Industry roadmaps indicate that the introduction of Extreme Ultraviolet Lithography (EUVL) is on track for high volume manufacturing. Although, there has been significant progress in each of the individual subsets of the EUVL infrastructure, the absolute management of the process outside of the scanner and up to the point-of-exposure has been highlighted as critical requirement for the adoption of EUVL. Significant changes in the EUV system environment and mask architecture are driving a zero process tolerance level. Any unforeseen contamination introduced to the scanner environment from the EUV mask could cause considerable downtime and yield loss. Absolute mask integrity at the point-of-exposure must be guaranteed. EUV mask cleaning processes-of-record have been developed and introduced to the industry [1]. The issue is not longer "how to clean the mask" but, "how to keep it clean". With the introduction of EUVL, mask cleanliness extends out beyond the traditional mask cleaning tool. Complete control of contamination and/or particles during transportation, handling and storage will require a holistic approach to mask management. A new environment specifically for EUV mask integrity must be developed and fully tested for the sub 16nm half-pitch node introduction. The SUSS MaskTrack® Pro (MTP) InSync was introduced as the solution for EUV mask integrity. SUSS demonstrated the fully automated handling of EUV masks into and out of a Dual Pod System [2]. Intrinsic cleanliness of each individual handling and storage step of the inner pod (EIP) and EUV mask inside the MTP InSync Tool was investigated and reported. A target specification of a PRP ≤ 0.08 as criterion for the cross contamination between EIP and the EUV reticle during handling within MTP InSync has been achieved and therefore proofing the applicability for the Dual Pod automation. Moreover an appropriate automated handling, other aspects like backside particle contamination and EIP cleanliness plays a significant role to ensure EUV mask integrity. With this concept in mind a system for particle detection has been integrated into MTP InSync. This allows verifying the POR performance for backside cleaning by measuring particles down to 150nm size. A dynamic capture rate of larger 97% at 200nm particle size based on PSLs was achieved; for EIP cleaning, a dry-cleaning technology is under investigation. During feasibility studies high particle removal efficiency (PRE) results larger 99% has been achieved for particles down to 100nm. In this paper, the full scope and roadmap of the MTP InSync will be discussed. Preliminary results of backside particle detection and challenges on EUV Inner Pod (EIP) cleaning will be presented.

Paper Details

Date Published: 29 June 2012
PDF: 12 pages
Proc. SPIE 8441, Photomask and Next-Generation Lithography Mask Technology XIX, 84411J (29 June 2012); doi: 10.1117/12.978198
Show Author Affiliations
O. Brux, SUSS MicroTec Photomask Equipment GmbH & Co. KG (Germany)
P. Dreß, SUSS MicroTec Photomask Equipment GmbH & Co. KG (Germany)
H. Schmalfuß, SUSS MicroTec Photomask Equipment GmbH & Co. KG (Germany)
R. Jonckheere, IMEC (Belgium)
W. Koolen-Hermkens, SUSS MicroTec Photomask Equipment GmbH & Co. KG (Germany)

Published in SPIE Proceedings Vol. 8441:
Photomask and Next-Generation Lithography Mask Technology XIX
Kokoro Kato, Editor(s)

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