Cmos-compatible read only memory and method for fabricating the same

Abstract

A CMOS-compatible read only memory (ROM) includes a first single-poly PMOS transistor that is serially electrically connected to a second single-poly PMOS transistor for recording digital data “1” or digital data “0”. The first and second single-poly PMOS transistors are both formed on an N-well of a P-type substrate. The first single-poly PMOS transistor includes a select gate electrically connected to a word line, a first P+ source doping region electrically connected to a source line, and a first P+ drain doping region. The second single-poly PMOS transistor includes a floating gate, a second P+ source doping region electrically connected to the first P+ drain doping region, and a second P+ drain doping region electrically connected to a bit line. The second P+ source doping region and the second P+ drain doping region define a floating gate channel region under the floating gate. A fast FPLD-to-ROM conversion method is also disclosed. After the final software code is fixed and the addresses where the memory units to be coded are determined, the FPLD are transformed into a ROM by either changing the layout of a photo mask that is used to define polysilicon gates to cancel the pre-selected floating gates according to the fixed software code, or by ion implanting the pre-selected floating gate channel regions underneath those floating gates where the memory units are to be coded.