Bias-Pulsed Atomic Layer Etching for Rapid Material Processing

Atomic layer etching (ALE) is a binary cyclical process renowned for its precise removal of atomic monolayers, making it ideal for fabricating nanotechnological devices; However, its slow effective etch rate, often less than a monolayer per minute (tenths or hundredths of an angstrom per second), limits its widespread use to niche applications requiring unparalleled precision. If the process were faster, semiconductor, optical, and quantum devices could regularly employ ALE, benefiting from its ability to achieve consistent critical dimensions and smoother post-etch surfaces, thereby enhancing overall device performance.<br/>The slow pace of ALE is primarily due to the time-consuming purge steps required to fully separate the chemical and physical phases of the cycle. Therefore, minimizing the duration of these purge steps is a logical strategy for speeding up the process. Bias-pulsed atomic layer etching (BP-ALE) addresses this challenge by using plasma etching in a simplified manner. Unlike traditional plasma ALE, which pulses multiple parameters such as gas flows, plasma DC bias, chamber pressure, and substrate temperature, BP-ALE achieves atomic precision by pulsing only the plasma DC bias. This method eliminates the need for gas purging, significantly reducing cycle time.<br/>BP-ALE has been successfully demonstrated on materials like 4H-SiC and diamond, achieving cycle durations of just 6 seconds compared to the minute-long cycles of conventional ALE, while also producing subangstrom RMS surface roughness. This presentation will detail the execution and potential applications of BP-ALE, outline the material and chemical characteristics necessary for its implementation, and predict material/chemistry systems suitable for BP-ALE processing.