Earlier quoted context omitted.
They go even smaller than 0.1mm. McMaster-Carr sells a 0.051mm drill bit for $25: https://www.mcmaster.com/8904A11/ That's the absolutely small I could find, though I suspect specialty vendors have even smaller ones. You can find MMC's other micro drill bits here: https://www.mcmaster.com/micro-drill-bits/ My only experience with these was in school where we used 0.25mm micro end mills (like a drill bit that cut side…
>0.051mm Holy shucks... How are they even manufactured? I imagine they have really precise grinding tools to make the flutes..
Sphinx uses laser ablation for their smallest drills (0.0030mm is their smallest catalog item, but they've made smaller as special order parts).