摘要:
A memory array (25) having a selected memory cell (10) and an unselected memory cell (30) is programmed and read. Each memory cell in the memory array (25) contains an isolation transistor (22) and a floating gate transistor (23). To program the selected memory cell (10), programming voltages are applied to a control gate line (21), a drain line (14), an isolation line (19), and a source line (12). To reduce the effects of the drain disturb problem, a gate terminal (32) of the unselected memory cell (30) is held at a positive voltage. To read selected memory cell (10), a read voltage is applied to an isolation gate line (31) of unselected memory cell (30) which insures that the unselected memory cell (30) does not conduct or contribute to leakage current and power consumption during the read operation.
摘要:
A nonvolatile memory (20) includes an array of floating gate transistors (22) organized as rows and columns. Word lines of adjacent rows are coupled together to form shared word lines. In one embodiment, a coupling transistor (56-61) is used to couple the sources of the floating gate transistors (36, 39-55) of a row to a predetermined potential in response to the shared word line being selected. The sources of the unselected floating gate transistors of the array (22) are isolated. In another embodiment, an inverter (113, 114, and 115) couples the sources to zero volts in response to the shared word line being selected. The conductivity of the floating gate transistors (36, 39-55) is controlled in response to the logic state of the shared word lines to ensure that unselected cells do not adversely affect the operation of the nonvolatile memory.
摘要:
An EEPROM device includes a split-gate FET (10) having a source (36), a drain (22), a select gate (16) adjacent the drain (22), and a control gate (32) adjacent the source (36). When programming the split-gate FET (10), electrons are accelerated in a portion of a channel region (38) between the select gate (16) and the control gate (32), and then injected into a nitride layer (24) of an ONO stack (25) underlying the control gate (32). The split-gate FET (10) is erased by injecting holes from the channel region (38) into the charge nitride layer (24). When reading data from the split-gate FET (10), a reading voltage is applied to the drain (22) adjacent the select gate (16). Data is then read from the split-gate FET (10) by sensing a current flowing in a bit line coupled to the drain (22).
摘要:
An EEPROM cell (40) includes a floating gate transistor (47) and an isolation transistor (45). Both a floating gate (48) and an isolation gate (46) are formed on a tunnel dielectric (44) within the cell. The isolation gate is coupled to a doped source region (52) of the floating gate transistor. The isolation transistor is not biased during a program operation of the cell, enabling a thin tunnel dielectric (less than 120 angstroms) to be used beneath all portions of both gates within the cell. Thus, the need for both a conventional tunnel dielectric and a gate dielectric is eliminated. The cell tolerates over-erasure, can be programmed at low programming voltages, and has good current drive due to the thin tunnel dielectric throughout the cell.
摘要:
A cross-point EEPROM memory array includes a semiconductor substrate (10) having first and second bit-lines (32, 34) spaced apart by a channel region (36). A control gate electrode (24) is formed by a portion of a control gate line, which overlies a first portion of the channel region (36) and is separated therefrom by an ONO layer (17). A select gate electrode (40) is formed by a portion of a select gate line disposed on the substrate (10) perpendicular to the control gate line. Individual cells in the array are programmed by injecting electrons using source-side injection into trapping sites (19) in the silicon nitride layer (14) of the ONO layer (17). The cells in the array are erased by electron tunneling through the top silicon dioxide layer (16) of the ONO layer (17), and are dissipated in the control gate electrode (24). Improved operating performance is obtained, in part, by fabricating the first silicon dioxide layer (12) of the ONO layer (17) to a greater thickness than the top silicon dioxide layer (16) of the ONO layer (17).
摘要:
An EEPROM cell (40) includes a floating gate transistor (47) and an isolation transistor (45). Both a floating gate (48) and an isolation gate (46) are formed on a tunnel dielectric (44) within the cell. The isolation gate is coupled to a doped source region (52) of the floating gate transistor. The isolation transistor is not biased during a program operation of the cell, enabling a thin tunnel dielectric (less than 120 angstroms) to be used beneath all portions of both gates within the cell. Thus, the need for both a conventional tunnel dielectric and a gate dielectric is eliminated. The cell tolerates over-erasure, can be programmed at low programming voltages, and has good current drive due to the thin tunnel dielectric throughout the cell.
摘要:
A non-linear charge pump (1120) provides various voltages for use in a nonvolatile memory (400) and operates at low power supply voltages. The non-linear charge pump (1120) includes at least two non-linear voltage doubling stages (1132, 1134), which allows a capacitor formed with relatively thin gate oxide in a first stage (1132) to be made larger than a capacitor formed using relatively thick gate oxide in a second stage (1134). An output of a last voltage doubling stage (1136) is then input to a linear stage (1150) to generate a precise voltage. Another charge pump (1140) including non-linear stages (1142, 1144) followed by a linear stage (1146) is used to generate a reference voltage for the main non-linear charge pump (1130). The nonlinear stage (1130) includes a special bulk biasing circuit to bias the bulk of a transistor (1285) on the output side of the charging circuit (1284, 1285, 1286, 1287) continuously to prevent forward biasing the parasitic drain-bulk diode.
摘要:
Methods of replacing/reforming a top oxide around a charge storage element of a memory cell and methods of improving quality of a top oxide around a charge storage element of a memory cell are provided. The method can involve removing a first poly over a first top oxide from the memory cell; removing the first top oxide from the memory cell; and forming a second top oxide around the charge storage element. The second top oxide can be formed by oxidizing a portion of the charge storage element or by forming a sacrificial layer over the charge storage element and oxidizing the sacrificial layer to a second top oxide.
摘要:
Methods of forming a top oxide around a charge storage material layer of a memory cell and methods of improving quality of a top oxide around a charge storage material layer of a memory cell are provided. The method can involve providing a charge storage layer on a semiconductor substrate, a nitride layer on the charge storage layer, and a first poly layer on the nitride layer, and converting at least a portion of the nitride layer to a top oxide. By converting at least a portion of a nitride layer to a top oxide layer, the quality of the resultant top oxide layer can be improved.
摘要:
A memory device and a method of making the memory device are provided. A first dielectric layer is formed on a substrate, a floating gate is formed on the first dielectric layer, a second dielectric layer is formed on the floating gate, a control gate is formed on the second dielectric layer, and at least one film, including a conformal film, is formed over a surface of the memory device.