Abstract: A single-poly two-transistor PMOS memory cell for multiple-time programming applications includes a PMOS floating gate transistor sharing a drain/source P+ diffusion region with a PMOS select gate transistor all formed within a first n-well. A control plate for the floating gate transistor is formed in a second n-well. A single-poly two-transitor PMOS memory cell for one-time programming applications includes a PMOS floating gate transistor having a source formed as a p+ diffusion region in a single n-well. The source is adapted to also serve as control plate for the floating gate transistor.

Abstract: A single-poly two-transistor PMOS memory cell for multiple-time programming applications includes a PMOS floating gate transistor sharing a drain/source P+ diffusion region with a PMOS select gate transistor all formed within a first n-well. A control plate for the floating gate transistor is formed in a second n-well. A single-poly two-transitor PMOS memory cell for one-time programming applications includes a PMOS floating gate transistor having a source formed as a p+ diffusion region in a single n-well. The source is adapted to also serve as control plate for the floating gate transistor.

Abstract: A program voltage of a first level is applied to the control gate of a PMOS floating gate memory cell to realize an injection of hot electrons induced by band-to-band tunneling (BTBT) into the floating gate of the cell. As the threshold voltage of the cell increases due to the accumulation of charge on the floating gate, the injection of BTBT induced hot electrons subsides. The program voltage is reduced to a second level which induces the injection of channel hot electrons (CHE) into the floating gate, thereby boosting the rate of charge accumulation on the floating gate.

Abstract: A nonvolatile memory array is disclosed which includes a plurality of PMOS two-transistor (2T) memory cells. Each 2T cell includes a PMOS floating gate transistor and a PMOS select transistor and is connected between a bit line and a common source line. The select gate and the control gate of each 2T cell in a common row are connected to a word line and to a control gate line, respectively. The 2T cells of the array are programmed using a combination of FN tunneling and BTBT induced hot electron injection, and are erased using FN tunneling. In some embodiments, the array is divided into sectors, where each sector is defined by an n- well region and includes a predetermined number of rows of the 2T cells. Here, the source of each 2T cell in a sector is coupled to a common source line of the sector. In other embodiments, the bit lines of the array are segmented along sector boundaries.

Abstract: A nonvolatile PMOS memory array includes a plurality of pages, where each column of a page includes two series-connected PMOS OR strings in parallel with a bit line. Each PMOS OR string includes a PMOS select transistor coupled between the bit line and two series connected PMOS floating gate memory cells. The PMOS floating gate memory cells are programmed via channel hot electron (CHE) injection and erased via electron tunneling. A soft-program mechanism is used to compensate for over-erasing of the memory cells. In some embodiments, the bit lines are segmented along page boundaries to increase speed.

Abstract: A P-channel single-poly EPROM cell has P+ source and P+ drain regions, and a channel extending therebetween, formed in an N-type well. A thin layer of tunnel oxide is provided over the channel and, in some embodiments, over significant portions of P+ source and P+ drain regions. A poly-silicon floating gate overlies the tunnel oxide. A P diffusion region is formed in a portion of the N-well underlying the floating gate and is thereby capacitively coupled to the floating gate. In this manner, the P diffusion region serves as a control gate for the memory cell. Programming is accomplished by coupling a sufficient voltage to the floating gate via the control gate while biasing the source and drain regions to cause the hot injection of electrons from the N-well/drain junction to the floating gate, while erasing is realized by biasing the floating gate, N-well, source and drain regions appropriately so as cause the tunneling of electrons from the floating gate to the N-well, the source, and the drain.

Abstract: A memory array includes a predetermined number of rows of PMOS Flash memory cells formed in each of a plurality of n- well regions of a semiconductor substrate, where each of the n- well regions defines a page of the memory array. In some embodiments, a plurality of bit lines define columns of the memory array, where the p+ drain of each of the memory cells in a common column are coupled to an associated one of the bit lines. In other embodiments, a plurality of sub-bit lines define columns of the memory array, where the p+ drain of each of the memory cells in a common column are coupled to an associated one of the sub-bit lines, and groups of a predetermined number of the sub-bit lines are selectively coupled to associated ones of a plurality of bit lines via pass transistors.

Abstract: A P-channel single-poly non-volatile memory cell having P+ source and P+ drain regions and a channel extending therebetween is formed in an N-type well. An overlying poly-silicon floating gate is separated from the N-well by a thin oxide layer. A P-type diffusion region is formed in a portion of the N-well underlying the floating gate and is thereby capacitively coupled to the floating gate. Within this P-type diffusion area lies an N-type diffusion area which serves as the control gate for the cell. The P-type diffusion region electrically isolates the control gate from the N-well such that voltages may be applied to the control gate in excess of those applied to the N-well without creating a current path from the control gate to the N-well. Programming is accomplished by coupling a sufficient voltage to the floating gate via the control gate while biasing the source and drain regions so as to cause the tunneling of electrons from the P+ drain region of the cell to the floating gate.

Abstract: A P-channel single-poly EPROM cell has P+ source and P+ drain regions, and a channel extending therebetween, formed in an N-type well. A thin layer of tunnel oxide is provided over the channel and, in some embodiments, over significant portions of P+ source and P+ drain regions. A poly-silicon floating gate overlies the tunnel oxide. A P diffusion region is formed in a portion of the N-well underlying the floating gate and is thereby capacitively coupled to the floating gate. In this manner, the P diffusion region serves as a control gate for the memory cell. Programming is accomplished by coupling a sufficient voltage to the floating gate via the control gate while biasing the source and drain regions to cause the hot injection of electrons from the N-well/drain junction to the floating gate, while erasing is realized by biasing the floating gate, N-well, source and drain regions appropriately so as cause the tunneling of electrons from the floating gate to the N-well, the source, and the drain.

Abstract: A semiconductor fabrication process allows for the fabrication of high-voltage transistors, logic transistors, and memory cells where, as required for sub-0.3 micron device geometries, the gate oxide of the logic transistors is thinner than the tunnel oxide thickness of the non-volatile memory cells without the undesirable contamination of the gate oxide of the logic transistors or contamination of the tunnel oxide of the memory cells. In one embodiment, the tunnel oxide of the memory cells is grown to a desired thickness. In a next step, a layer of doped polysilicon which will serve as the floating gate of the memory cell(s) is immediately deposited over the tunnel oxide of the memory cells, thereby protecting the tunnel oxide from contamination in subsequent masking and etching steps. The gate oxide of the logic transistors and the gate oxide of the high-voltage transistors are then grown to a desired thickness.

Abstract: A P-channel MOS memory cell has P+ source and drain regions formed in an N-well. A thin tunnel oxide is provided between the well surface and an overlying floating gate. In one embodiment, the thin tunnel oxide extends over a substantial portion of the active region and the device. An overlying select and control gate is insulated from the floating gate by an insulating layer. The select and control gate including an elongated extension portion for preventing overprogramming of the circuit. The device is programmed via hot electron injection from the drain end of the channel region to the floating gate, without avalanche breakdown, which allows the cell to be bit-selectable during programming. Erasing is accomplished by electron tunneling from the floating gate to the N-well with the source, drain, and N-well regions equally biased. Since there is no high drain/well junction bias voltage, the channel length of the cell may be reduced without incurring and destructive junction stress.

Abstract: A P-channel MOS memory cell has P+ source and drain regions formed in an N-well. A thin runnel oxide is provided between the well surface and an overlying floating gate. In one embodiment, the thin tunnel oxide extends over a substantial portion of the active region and the device. An overlying control gate is insulated from the floating gate by a first insulating layer. An overlying select gate is insulated from the control gate by an insulating layer. The select gate includes an elongated extension portion for preventing overprogramming of the circuit. The device is programmed via hot electron injection from the drain end of the channel region to the floating gate, without avalanche breakdown, which allows the cell to be bit-selectable during programming. Erasing is accomplished by electron tunneling from the floating gate to the N-well with the source, drain, and N-well regions equally biased.

Abstract: A P-channel MOS memory cell has P+ source and drain regions formed in an N-well. A thin tunnel oxide is provided between the well surface and an overlying floating gate. In one embodiment, the thin tunnel oxide extends over a substantial portion of the active region and the device. An overlying control gate is insulated from the floating gate by an insulating layer. The device is programmed via hot electron injection from the drain end of the channel region to the floating gate, without avalanche breakdown, which allows the cell to be bit-selectable during programming. Erasing is accomplished by electron tunneling from the floating gate to the N-well with the source, drain, and N-well regions equally biased. Since there is no high drain/well junction bias voltage, the channel length of the cell may be reduced without incurring and destructive junction stress.

Abstract: A P-channel flash EEPROM cell has P+ source and P+ drain regions, and a channel extending therebetween, formed in an N-type well. A thin layer of tunnel oxide is provided over the channel. A poly-silicon floating gate and poly-silicon control gate, separated by a dielectric layer, overlie the tunnel oxide. Programming is accomplished via hot electron injection while erasing is realized by electron tunneling. The threshold voltage of the cell may be precisely controlled by the magnitude of voltage coupled to the floating gate during programming. Since the injection of hot electrons into the floating gate is independent of variations in the thickness of the tunnel oxide layer and the coupling ratio between the floating gate and the control gate, programming operations and data retention are not affected by process variations.