I've seen electronic microscope image of a working polar transistor in few dozens of atoms. Wires were couple atoms wide. The method employed for that scale was

I've seen electronic microscope image of a working polar transistor in few dozens of atoms. Wires were couple atoms wide. The method employed for that scale was able to place about couple of hundreds of tungsten atoms per second. It was in 2005. I lost contact with these people, I don't know how they do now.