Chemically controlled megasonic cleaning of patterned structures using solutions with dissolved gas and surfactant

Bichitra Nanda Sahoo, So Young Han, Hyun Tae Kim, Keita Ando, Tae Gon Kim, Bong Kyun Kang, Andreas Klipp, Nagendra Prasad Yerriboina, Jin Goo Park

Research output: Contribution to journalArticlepeer-review

Abstract

Acoustic cavitation is used for megasonic cleaning in the semiconductor industry, especially of wafers with fragile pattern structures. Control of transient cavitation is necessary to achieve high particle removal efficiency (PRE) and low pattern damage (PD). In this study, the cleaning performance of solutions with different concentrations of dissolved gas (H2) and anionic surfactant (sodium dodecyl sulfate, SDS) in DIW (DI water) on silicon (Si) wafers was evaluated in terms of PRE and PD. When only DIW was used, PRE was low and PD was high. An increase in dissolved H2 gas concentration in DIW increased PRE; however, PD also increased accordingly. Thus, we investigated the megasonic cleaning performance of DIW and H2-DIW solutions with various concentrations of the anionic surfactant, SDS. At 20 ppm SDS in DIW, PRE reached a maximum value and then decreased with increasing concentration of SDS. PRE decreased slightly with increasing concentrations of SDS surfactant when dissolved in H2-DIW. Furthermore, PD decreased significantly with increasing concentrations of SDS surfactant in both DIW and H2-DIW cases. A high-speed camera setup was introduced to analyze bubble dynamics under a 0.96 MHz ultrasonic field. Coalescence, agglomeration, and the population of multi-bubbles affected the PRE and PD of silicon wafers differently in the presence of SDS surfactant. We developed a hypothesis to explain the change in bubble characteristics under different chemical environmental conditions.

Original languageEnglish
Article number105859
JournalUltrasonics Sonochemistry
Volume82
DOIs
Publication statusPublished - 2022 Jan

Keywords

  • Acoustic bubble cavitation
  • Dissolved gas
  • Megasonic cleaning
  • Particle removal
  • Pattern damage
  • Surfactant

ASJC Scopus subject areas

  • Chemical Engineering (miscellaneous)
  • Environmental Chemistry
  • Radiology Nuclear Medicine and imaging
  • Acoustics and Ultrasonics
  • Organic Chemistry
  • Inorganic Chemistry

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