Dry-wet digital etching of Ge_(1-x)Sr_x

摘要

The development of a precise micromachining process for Ge_(1-x)Sr_x has the potential to enable both the fabrication and optimization of Ge_(1-x)Sr_x-based devices in photonics and microelectromechanical systems. We demonstrate a digital etching scheme for Ge_(0.922)Sn_(0.078) based on a two-stage, highly selective CF_4 plasma dry etch and HC1 wet etch. Using X-Ray Reflectivity, we show consistent etch control as low as 1.5 nm per cycle, which is defined as one dry etch step followed by one wet etch step. The etch rate increases to 3.2 nm per cycle for a longer dry etch time due to physical sputtering contributions, accompanied by an increase in RMS surface roughness. By operating within a regime with minimal sputtering, we demonstrate that good digital etch depth control and surface quality can be achieved using this technique.