In situ studies of a possible atomic layer etching process of copper.

Sammanfattning

As semiconductor manufacturing moves toward atomic-scale precision, conventional etching methods face limitations in selectivity and control. This thesis investigates the possibility of using hexafluoroacetylacetone (Hhfac) as a precursor in an electron-assisted atomic layer etching (e-ALE) process for copper substrates. The proposed method involves repeated exposure of copper to Hhfac, followed by low-energy plasma electron bombardment to induce selective etching. A combination of in-situ and ex-situ analytical techniques was employed, including quartz crystal microbalance (QCM), mass spectrometry (MS), optical emission spectroscopy (OES), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). QCM results revealed a net mass loss of copper per cycle, consistent with atomic layer etching behaviour. MS and OES confirmed the presence of fluorinated species and ionized copper, while XPS analysis indicated Cu–F bond formation. SEM imaging showed notable changes in surface morphology following etch cycles. Together, these findings support the hypothesis that Hhfac can facilitate controlled etching of copper through a plasma-assisted process. The results contribute to the development of precise and potentially more environmentally sustainable techniques for the future of nanotechnology.