Silicon dioxide mask by plasma enhanced atomic layer deposition in focused ion beam lithography

Zhengjun Liu*, Ali Shah, Tapani Alasaarela, Nikolai Chekurov, Hele Savin, Ilkka Tittonen

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

7 Citations (Scopus)


In this work, focused ion beam (FIB) lithography was developed for plasma enhanced atomic layer deposited (PEALD) silicon dioxide SiO2 hard mask. The PEALD process greatly decreases the deposition temperature of the SiO2 hard mask. FIB Ga+ ion implantation on the deposited SiO2 layer increases the wet etch resistivity of the irradiated region. A programmed exposure in FIB followed by development in a wet etchant enables the precisely defined nanoscale patterning. The combination of FIB exposure parameters and the development time provides greater freedom for optimization. The developed process provides high pattern dimension accuracy over the tested range of 90-210 nm. Utilizing the SiO2 mask developed in this work, silicon nanopillars with 40 nm diameter were successfully fabricated with cryogenic deep reactive ion etching and the aspect ratio reached 16: 1. The fabricated mask is suitable for sub-100 nm high aspect ratio silicon structure fabrication.

Original languageEnglish
Article number085303
Number of pages7
Issue number8
Publication statusPublished - 24 Feb 2017
MoE publication typeA1 Journal article-refereed


  • FIB lithography
  • PEALD SiO2
  • HAR silicon machining
  • resist-free
  • nanofabrication
  • SIO2


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