Dies are one dimensional, making multi dimensional dies is the next challenge in IC manufacturing.
Today we do use 2.5D transistors AKA FinFets but that's still as single layer.
Multiple masks are used however as creating the feature size expected today with the wavelengths we have requires multiple patterning which means multiple masks are used.
14nm today still uses the same 193nm lithography from 65nm if not earlier, the only way to create features which are actually smaller than the wavelength of the light is by using multiple hard mask and resist layers.
Today we do use 2.5D transistors AKA FinFets but that's still as single layer.
Multiple masks are used however as creating the feature size expected today with the wavelengths we have requires multiple patterning which means multiple masks are used.
14nm today still uses the same 193nm lithography from 65nm if not earlier, the only way to create features which are actually smaller than the wavelength of the light is by using multiple hard mask and resist layers.