IFC s an open building model file format. It is mostly used for exchanging models between programs (such as ArchiCAD, Revit, Tekla, etc.). I have no idea why it would create that file in the circumstances you describe. In any case I doubt it is anything to worry about.
Archicad does some background processing all the time concerning IFC - 've seen "IFC something Tree"-messages now and then. I would guess it does some management just to keep the IFC saving process available and possible at all times. While doing this, it may create temporary files now and then, iles that you normally don't see because they're cleared away when Archicad doesn't need them anymore. But at a power outage, you'd see them because ther ws no time to get rid of them.
If you have opened your Autosave or backup and all is well, after you have saved the project and quit Archicad normally I'm sure you can delete this file if it still remains.