$10\mathrm{.}3.$ In a certain process, it is desired that the pitch of metal lines be equal to or less than $\backslash (1\mathrm{.}0\backslash$mu $\backslash$mathrm$\{$~m$\}\backslash )($the pitch equals one metal linewidth plus one spacing between metal lines, measured at top of features$).$ Assume that the metal finewidth and spacing are equal $($that is$,\backslash (0\mathrm{.}5\backslash$mu $\backslash$mathrm$\{$~m$\}\backslash )$ each$).$ The height of such structures is also $\backslash (0\mathrm{.}5\backslash$mu $\backslash$mathrm$\{$~m$\}\backslash ),$ and the minimum lithographic dimension is $\backslash (0\mathrm{.}25\backslash$mu $\backslash$mathrm$\{$~m$\}\backslash ).$

a$.$ What minimum degree of anisotropy is needed in an etch process in order to produce such a structure?

b$.$ What minimum pitch could be obtained for such a structure with wet etching? $($Again with minimum lithograph dimension of $\backslash (0\mathrm{.}25\backslash$mu $\backslash$mathrm$\{$~m$\}\backslash ),$ thickness of $\backslash (0\mathrm{.}5\backslash$mu $\backslash$mathrm$\{$~m$\}\backslash ),$ and equal metal width and spacing.$)$