We developed a pillar-shaped microelectrode array (MEA) with varying heights for enhancing the spherical conformity of fully implantable epiretinal prosthesis comprising a 3D stacked retinal chip. The fabricated MEA is composed of 100 pillar electrodes with heights ranging from 60 to 80 μm. The Pt-coated Cu pillar electrode with a surface diameter of 70m and a height of 75 μm and the Pt planar electrode with a surface diameter of 70 μm have 24.6 and 125 kΩ impedances, respectively, at 1kHz in vitro experiment. The pillar electrode shows lower impedance than the planar electrode because of a larger surface area. However, to avoid cross-talking between pillar electrodes, we developed a sidewall passivation process of the pillar electrode by using the surface tension of polyimide. The impedance of the isolated pillar electrode 116 kΩ at 1kHz is similar to the impedance of the planar electrode, because they have similar electrode surface areas. The pillar-shaped MEA shows a better spherical conformity.