Surface modification of the MoSiON phase shift mask to reduce critical dimension variation

Hyeokseong Choo, Dongwan Seo, Sangwoo Lim

Research output: Contribution to journalArticle

Abstract

Phase shift masks (PSMs) were introduced to extend the limits of optical lithography. However, cleaning a MoSiON-based PSM pattern with an ammonium hydroxide/hydrogen peroxide mixture (APM), although efficient at cleaning the PSM pattern, etches the PSM layer, inducing changes in the phase angle and transmittance due to the introduction of variation of the critical dimension (CD). In this study, we investigated the effects of plasma treatment and furnace annealing on the etching of the MoSiON PSM in APM. In particular, we found that the etch behavior and surface chemical state after each treatment were correlated. We also compared variations in the CD between patterned PSM layers and blank masks. After O 2 or N 2 plasma treatment, the top surface of MoSiON had a thicker transition layer with an extreme increase in O, and a huge variation in CD was also observed after APM treatment. However, CD variation of the patterned MoSiON layer was minimal when the sample was first annealed in NH 3 ambient gas and then subjected to APM treatment. This phenomenon may be related to an increase in the portion of the SiO 2 -like state at the top surface of the MoSiON PSM layer and its optimization without a change in the transition layer thickness.

Original languageEnglish
Pages (from-to)320-325
Number of pages6
JournalApplied Surface Science
Volume282
DOIs
Publication statusPublished - 2013 Oct 1

All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Condensed Matter Physics
  • Physics and Astronomy(all)
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films

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