Ruthenium (Ru) peeling and predicting robustness of the capping layer using finite element method (FEM) modeling

Il Yong Jang, Arun John, Frank Goodwin, Su Young Lee, Byung Gook Kim, Seong Sue Kim, Chan Uk Jeon, Jae Hyung Kim, Yong Hoon Jang

Research output: Chapter in Book/Report/Conference proceedingConference contribution

7 Citations (Scopus)


Ruthenium (Ru) film used as capping layer in extreme ultraviolet (EUV) mask peeled off after annealing and in-situ UV (IUV) cleaning. We investigated Ru peeling and found out that the mechanical stress caused by the formation of Si oxide due to the penetration of oxygen atoms from ambient or cleaning media to top-Si of ML is the root cause for the problem. To support our experimental results, we developed a numerical model of finite element method (FEM) using commercial software (ABAQUS™) to calculate the stress and displacement forced on the capping layer. By using this model, we could observe that the displacement agrees well with the actual results measured from the transmission electron microscopy (TEM) image. Using the ion beam deposition (IBD) tool at SEMATECH, we developed four new types of alternative capping materials (RuA, RuB, B4C, B4C-buffered Ru). The durability of each new alternative capping layer observed by experiment was better than that of conventional Ru. The stress and displacement calculated from each new alternative capping layer, using modeling, also agreed well with the experimental results. A new EUV mask structure is proposed, inserting a layer of B4C (B4C-buffered Ru) at the interface between the capping layer (Ru) and the top-Si layer. The modeling results showed that the maximum displacement and bending stress observed from the B4C-buffered Ru are significantly lower than that of single capping layer cases. The durability investigated from the experiment also showed that the B4C-buffered structure is at least 3X stronger than that of conventional Ru.

Original languageEnglish
Title of host publicationPhotomask and Next-Generation Lithography Mask Technology XXI
EditorsKokoro Kato
ISBN (Electronic)9781628413236
Publication statusPublished - 2014
EventPhotomask and Next-Generation Lithography Mask Technology XXI - Yokohama, Japan
Duration: 2014 Apr 152014 Apr 17

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
ISSN (Print)0277-786X
ISSN (Electronic)1996-756X


OtherPhotomask and Next-Generation Lithography Mask Technology XXI

Bibliographical note

Publisher Copyright:
© 2014 SPIE.

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering


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