4. Now we are designing a process to produce aluminum metal lines of pitch 1.0 µm and height ($t_f$) 0.5 µm. Assume that the metal linewidth and spacewidth are equal (that is, 0.5 µm each, as measured at the top of the metal lines). Due to the presence of anisotropy A = 0.75 of the process, the photoresist has to be uneven block- and open-widths.
(a) [20 Pts.] What open-width x of resist should be in order to produce such a structure?
(b) [20 Pts.] Assume the same resist opening width, what minimum pitch could be obtained for such a structure with wet etching? (Again, metal thickness is 0.5 µm, and we want equal metal width and spacing as measured at the top.)
