公开(公告)号：FR2826169A1

公开(公告)日：2002-12-20

申请号：FR0107872

申请日：2001-06-15

Applicant: ST MICROELECTRONICS SA

Inventor： THOMAS SIGRID

IPC: G11C17/12 ,  H01L21/8246 ,  H01L27/112 ,  G11C17/08

Abstract: The read-only memory store is constituted of cells wherein each programmed cell (20) comprises a series connection of a memory element (22) and a selection transistor (4) connected between a selection line (SL) and a bit line (BL). The selection transistor is of MOS type and its gate (5) is connected to a read line (RL). The memory element (22) is no longer a MOS transistor as in known programmable cells, but an active zone (26) which is uniformly n-type doped and acts as a resistance. The memory element of a non-programmed cell is p-MOS transistor whose gate is connected to that of the selection transistor, or left unconnected as in programmable cells. The read-only memory is implemented in the same integrated circuit chip as a programmable memory, where the selection lines of the read-only memory and the programmable memory are connectable to a selection supply voltage (VDD), and the selection lines of the programmable memory are selectively connectable to a write supply voltage (VPP), which is higher than the selection supply voltage. A method for making the read-only memory in a monocrystalline semiconductor substrate comprises the steps of defining the active zones (11,26) in the same dimension, forming an insulated line (5) above the active zone (11), implanting the exposed parts of the active zones, depositing an insulator on the obtained structure, opening the insulator so to partially expose the active zones in the neighbourhood of each extremity, and forming the selection lines (SL) in contact with the active zones (26), conducting links (9) so to pair up the active zones (11,26) and the bit lines (BL) in contact with the active zones (11).