Node names stopped meaning anything a long time ago, it's not really 3nm, that's just the marketing name. Think 11 inch "Footlong" but more extreme.
That being said, direct S/D tunneling is expected to become an issue at channel lengths of around 1nm, although anisotropic carrier mass can be used to delay this further.
That being said, direct S/D tunneling is expected to become an issue at channel lengths of around 1nm, although anisotropic carrier mass can be used to delay this further.