Specifically, to etch layers anisotropically has advantages over isotropic etching in defining the underlying gap, e.g. gap region 3108A. Next, preferred embodiments deposit 3015 insulating material layer 3115??? such material may be SiO2, Si3N4, Al2O3, or other insulating materials, for example, as illustrated in FIG. 25AX. Next, preferred embodiments CMP etch then directly etch 3017 insu