This video shows a pcb's manufacture process of 6 layers with microrvias and buried via
Playing the video you can see the main phases of the manufacture process :
Photosensitive film application, Insolation, Optical test, Multilayer press, Drilled, Desmear, Blackhole, Electrolytic plated, Laser microvies, Solder mask, Ink legend, Plated finish, Electrical test.