Passivation of poly-Si surface using vinyl and epoxy group additives for selective Si3N4 etching in H3PO4 solution

Taegun Park, Taehyeon Kim, Changjin Son, Sangwoo Lim

Research output: Contribution to journalArticlepeer-review


This work investigates the mechanism of polycrystalline silicon (poly-Si) dissolution in H3PO4. The etching rate of poly-Si was more rapid than that of silicon dioxide (SiO2) in H3PO4 solution, because poly-Si surface possesses unstable Si1+, Si2+, and Si3+ states – rather than Si4+, which is more stable. Additives such as epichlorohydrin, 1,2-epoxy-3-phenoxypropane, vinyl bromide, and phenyl vinyl ether with epoxy or vinyl groups were introduced into the H3PO4 to passivate the poly-Si surface. This significantly increased the presence of the Si4+ state and provided hydrophobic functional groups on the poly-Si surface to reduce the wettability of the poly-Si surface. The introduction of these additives significantly reduced the etching rate of poly-Si. 3-glycidyloxypropyl trimethoxysilane, 3-glycidyloxypropyl dimethoxymethylsilane, allyltrimethoxysilane, and vinyltrimethoxysilane with Si–O bonds, as well as epoxy or vinyl groups in their molecular structures, were demonstrated to suppress the etching rate of both SiO2 and poly-Si. The introduction of these additives to H3PO4 promoted the selective removal of silicon nitride (Si3N4) layers from multi-layered Si3N4/SiO2 trench structures without the loss of either poly-Si or SiO2.

Original languageEnglish
Article number155143
JournalApplied Surface Science
Publication statusPublished - 2023 Jan 15

Bibliographical note

Funding Information:
The authors gratefully acknowledge financial support from SK hynix incorporation.

Publisher Copyright:
© 2022 Elsevier B.V.

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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