In method for forming a semiconductor device, a first opening is formed in a dielectric stack that has a cylinder shape with a first sidewall. A first conductive layer is deposited along the first sidewall of the first opening and a first insulating layer is deposited along an inner sidewall of the first conductive layer. The dielectric stack is then etched along an inner sidewall of the first insulating layer so as to form a second opening that extends into the dielectric stack with a second sidewall. A second conductive layer is further formed along the second sidewall of the second opening and a second insulating layer is formed along an inner sidewall of the second conductive layer. A bottom of the second conductive layer is positioned below a bottom of the first conductive layer to form a staggered configuration.