Patent ID: 7906392

Claim:
A method of making a semiconductor device, comprising: forming a plurality of lower electrodes over a substrate; forming an insulating layer containing a plurality of first openings having a first width, such that the lower electrodes are exposed in the first openings; forming first semiconductor regions of a first conductivity type in the first openings; forming a sacrificial material in the plurality of first openings over the first semiconductor regions; forming a plurality of second openings in the insulating layer to expose the sacrificial material, the second openings having a second width greater than the first width; removing the sacrificial material from the first openings through the second openings; forming second semiconductor regions of a second conductivity type in the first openings, wherein the first and the second semiconductor regions form pillar shaped diodes in the first openings; and forming upper electrodes in the second openings in the insulating layer such that the upper electrodes contact the second semiconductor regions.