There are all sorts of techniques you can use to create features smaller than the wavelength. Optical Proximity Correction, Immersion, phase-shifting, multi-patterning, etc:

https://en.wikipedia.org/wiki/Immersion_lithography

https://en.wikipedia.org/wiki/Optical_proximity_correction

https://en.wikipedia.org/wiki/Phase-shift_mask

https://en.wikipedia.org/wiki/Multiple_patterning