公开(公告)号：US20250120318A1

公开(公告)日：2025-04-10

申请号：US18908317

申请日：2024-10-07

Applicant: California Institute of Technology

Inventor： Harold Frank Greer ,  Jenni Solgaard ,  Ivy Chen ,  Austin Minnich ,  Alireza Marandi ,  Ryoto Sekine

IPC: H10N30/082 ,  H01L21/67

Abstract: Lithium niobate (LiNbO3, LN) is a ferroelectric crystal of interest for integrated photonics owing to its large second-order optical nonlinearity and the ability to impart periodic poling via an external electric field. However, on-chip device performance based on thin-film lithium niobate (TFLN) is presently limited by propagation losses arising from surface roughness on the nano- and microscale. Atomic layer etching (ALE) can smooth these features and thereby increase photonic performance. In one embodiment disclosed herein, an isotropic ALE process for x-cut MgO-doped LN uses sequential exposures of H2 and SF6/Ar plasmas. We observed an etch rate of 1.59±0.02 nm/cycle with a synergy of 96.9%. ALE can be achieved with SF6/O2 or Cl2/BCl3 plasma exposures in place of the SF6/Ar plasma step with synergies of 99.5% and 91.5% respectively. The process decreased the sidewall surface roughness of TFLN waveguides etched by physical Ar+ milling by 30% without additional wet processing.