A method of making a semiconductor device includes forming at least one device layer over a substrate, forming a plurality of spaced apart first features over the device layer, where each three adjacent first features form an equilateral triangle, forming sidewall spacers on the first features, filling a space between the sidewall spacers with a plurality of filler features, selectively removing the sidewall spacers, and etching the at least one device layer using at least the plurality of filler features as a mask. A device contains a plurality of bottom electrodes located over a substrate, a plurality of spaced apart pillars over the plurality of bottom electrodes, and a plurality of upper electrodes contacting the plurality of pillars. Each three adjacent pillars form an equilateral triangle, and each pillar comprises a semiconductor device. The plurality of pillars include a plurality of first pillars having a first shape and a plurality of second pillars having a second shape different from the first shape.