Abstract: A ROM device includes cells with buried bit lines in a semiconductor substrate. A thin insulating layer covers the substrate has closely spaced, parallel, word lines formed thereon arranged orthogonally relative to the bit lines. The word lines are covered with reflowed glass insulating layers about 2500.ANG. thick. The glass insulating layers comprise a sublayer of undoped glass and an overlayer of doped glass, the underlayer about 500.ANG.-1500.ANG. thick and the overlayer about 1000.ANG.-1500.ANG. thick. An etched, patterned metal layer is formed on the glass insulating layer. The overlayer has been substantially removed by etching where the metal layer has been etched. An ion implantation pattern has been implanted into the substrate adjacent to the conductive lines. The device has been passivated. The implanted impurity ions having been activated by annealing the device.