Direct tunneling in the channel becomes a problem < 4nm. the gate insulator can be even thinner since they use high dielectric constant ones which limits the tu

Direct tunneling in the channel becomes a problem < 4nm. the gate insulator can be even thinner since they use high dielectric constant ones which limits the tunneling current. As GP mentioned the main problem with 10nm is the photolithographic process. Currently they're using 193nm ArF lasers. EUV "light" is very difficult to generate and handle. There aren't even lenses for it, only lossy mirrors, so each optics step will lose you a fraction of the input power and heat the mirrors.