Traditional methods of IC manufacture involve etching unwanted semiconductor material from a preexisting chip, in the same way a sculptor carves a statue. Futurists suggest that, rather than etching switches and logic gate s into semiconductor material, chips ought to be mechanically assembled one molecule at a time. Some scientists believe ICs can be grown from biological seeds, just as a plant reproduces cells to create a defined structure such as a tree. Both of these processes involve nanotechnology , and would result in the greatest possible number of switches per unit volume of material substance.