Atomic layer etching processes for low-damage patterning and in-situ passivation of semiconductor materials


Thin-film technologies such as atomic layer deposition (ALD) play a significant role in the ongoing miniaturization in the semiconductor industry. This technology enables 3D structures to be deposited and layer thicknesses to be precisely adjusted. In the current "ALEStar" project, ALD processes are to be combined with novel etching processes such as atomic layer etching (ALE) to realize nitride devices with precisely tunable electrical properties. Compared to silicon, nitride semiconductor materials, such as gallium nitride (GaN), aluminum nitride (AlN) and their ternary compounds AlGaN, are characterized by high electron mobility, breakdown voltage and a large direct band gap. Therefore, nitride semiconductor materials are particularly suitable for high-frequency applications and high-voltage electronics.

ALE technology offers two major advantages to increase efficiency in the fabrication of high performance nitride devices. On the one hand, the atomic layer precise ALE process allows a more accurate fabrication of the very low step heights especially in the contact and gate area with simultaneously reduced damage compared to previous dry chemical etching processes such as Rapid Ion Etching (RIE). On the other hand, the self-limitation of the process promises high lateral homogeneity over the entire wafer. In addition, the researchers are looking into the possibility of in-situ passivation of the etched layer by depositing thin film dielectrics. The process development is supported by an accompanying characterization of the materials used. In addition, the surface condition of the test components after processing as well as their functionality will be investigated. This enables monitoring of the etching process at an early stage of development.

Another focus of the project is the evaluation of etching gases. The aim is to examine what alternatives there are to chlorine-containing etching gases and what environmental and technical advantages are associated with them.


Abbildung: Schematische Darstellung eines MISHFETs auf Saphir-Substrat. Durch Polarisationseffekte an der AlGaN/GaN-Heterostruktur bildet sich ein zweidimensionales Elektronengas (2DEG) aus (links). MISHFET mit rückgeätztem Gate- und Source/Drain-Kontaktbereich (rechts). [Adaption aus der Dissertation von Alexander Schmid: "Untersuchungen zu Vanadium-basierten ohmschen Kontakten in AlGaN/GaN-MISHFETs", 2020].

Project name:  Development[A1]  of atomic layer etching processes for low-damage patterning of semiconductor materials and their in-situ passivation. (ALEStar)

Funding: Sächsisches Staatsministerium für Wirtschaft, Arbeit und Verkehr

Funding code: 100401562, 100401564

Project period: 01.07.2020 - 31.03.2022

Project partner: Fraunhofer Technology Center High Performance Materials THM, branch of the Fraunhofer Institute for Integrated Systems and Device Technology IISB

 [A1]sind die Unterstreichungen in der englischen Übersetzung so sinnvoll?, deutscher Satz war: Entwicklung von Atomlagen-Ätzprozessen zur schädigungsarmen Strukturierung von Halbleitermaterialien und deren in-situ Passivierung