An apparatus for an ion trap includes an electrically conductive substrate
having top and bottom surfaces and having vias that cross from the top
surface to the bottom surface. The apparatus includes a pair of planar
first electrodes supported over said top surface and second electrodes
having planar surfaces. The planar surfaces are located over said top
surface, and portions of the planar surfaces are located laterally
adjacent to said planar first electrodes. One of the second electrodes
includes a portion that is located in one of the vias and traverses the
substrate.