When semiconductors meets insulating layers
Understanding interface formation between InAs semiconductors and hafnium dioxide insulating layers
Most semiconductor devices are still based on silicon, even though other semiconductor materials such as InAs have superior electrical properties. The problem with these materials is that their interface towards thin insulating layers, which are needed for e.g. transistor processing, contains many defects which hamper device performance. Strong efforts are going on in many places to improve this interface between III-V semiconductors and so-called high-k insulating layers.
A research team with scientists from NanoLund and MAX IV recently reported that the chemical model which has generally been used to describe formation of this interface is too simplified. The researchers monitored the surface chemistry during the formation of hafnium dioxide on InAs in an atomic layer deposition process using ambient-pressure X-ray photoelectron spectroscopy at MAX-lab. They observed an unexpected two-step reaction, where the removal of unwanted oxides and defects could clearly be distinguished from the formation of the insulating hafnium dioxide layer. This observation suggests a path to optimize the deposition process and enable better interfaces. The study will be continued with strongly improved time resolution at the new HIPPIE beamline at MAX IV.
Read the paper published in Nature Communications: “Self-cleaning and surface chemical reactions during hafnium dioxide atomic layer deposition on indium arsenide” by R. Timm, A. Head, S. Yngman, J. Knutsson, M. Hjort, S. McKibbin, A. Troian, O. Persson, S. Urpelainen, J. Knudsen, J. Schnadt, and A. Mikkelsen, Nature Commun. 9, 1412 (2018), DOI: 10.1038/s41467-018-03855-z.