The 13 layers Retric was referring to are not layers of transistors, but layers of wiring. All chips currently manufactured only have a single layer of transistors. Above this single layer of transistors are many layers for wires which are alternatingly used for wires mostly in X- and mostly in Y-direction.

That's what I had thought (and reflected in my brief comment - "transistors within the 1 plane") - it seemed they corrected me, to my surprise. Thanks.