Method of manufacturing contact programmable ROM

A method for manufacturing a contact programmable read only memory device, said method comprising the sequential steps of:

• forming first and second memory cells prior to programming the device, each of which has a gate region and a source/drain region on a semiconductor substrate,
• forming a first interlayer insulating layer over the whole surface of the semiconductor substrate on which said memory cells are formed,
• forming a plurality of first openings on said first interlayer insulating layer so that source/drain regions of said first and second memory cells are exposed,
• forming a plurality of contact holes and then connecting said contact holes to said source/drain regions by filling said first openings with metal interconnect material, prior to programming the device,
• forming a second interlayer insulating layer over said filled metal interconnect material and said first interlayer insulating layer,
• forming a second opening on said second interlayer insulating layer so that the surface of said metal interconnect material connected to the source/drain region of said second memory cell is exposed, and
• programming said device by forming an interconnecting layer connected electrically to the contact hole of said second memory cell, but not the contact hole of said first memory cell, by filling said second opening, said filling being in accordance with a program such that said second memory cell is permanently programmed to a logic value different than a logic value of said first memory cell.