Abstract: A method of eliminating contamination of tunnel oxide in stacked gates due to SAS photoresist process and preventing of n+ implantation caused by resist residue from the SAS photoresist process in fabricating of semiconductor memory devices is disclosed. The process provides for providing stacked gates separated by trenches on the semiconductor memory device. Source and drain implants are performed on the semiconductor memory device before the SAS etch is accomplished. The trenches between the stacked gates are filled with oxide so as to cover the entire surface of the semiconductor memory device prior to applying a SAS photoresist mask. Then, a SAS photoresist mask is applied to a flat top surface of the semiconductor memory device. A SAS etch is performed on the semiconductor memory device so as to remove the oxide.

Abstract: A unified program method and circuitry for performing concurrently a programming and verifying operation in an array of Flash EEPROM memory cells is provided. Each of the memory cells includes a floating gate array core transistor. A single bandgap voltage is provided which corresponds to a predetermined amount of drain current at which programming is to be terminated. A program voltage is selectively connected to at least one of the columns of array bit lines containing the array core transistor which is to be programmed. A control gate bias voltage corresponding to a programmable memory state is selectively connected to the gate of the array core transistor. A core cell current flowing through the array core transistor and the predetermined amount of drain current is compared. The program voltage is disconnected so as to terminate automatically programming of the array core transistor when the core cell current falls below the predetermined amount of drain current.

Abstract: A method and apparatus for providing a charge pump that is particularly useful for generating high voltages and high currents for erasing and programming flash electrically-erasable programmable read only memory arrays (Flash EEPROMs). The invention includes an efficient method and circuit for generating a pumped voltage with no voltage drop from one stage to the next by using a simple two-phase clocking scheme and an auxiliary pump to gate a larger primary pump. One feature allows adjustment of the level of voltage pumping to accommodate higher voltage power supplies.

Abstract: An output noise control circuit with significantly reduced power/ground bounce characteristics when multiple outputs thereof are being simultaneously switched is provided. The output noise control circuit includes a plurality of output buffers each being formed of an output driver stage, a first pre-driver stage, and a second pre-driver stage. Each of the output driver stages includes a pull-up drive transistor and a pull-down drive transistor. Each of the first pre-driver stages includes a first inverter, and each of said second pre-driver stages includes a second inverter. A shared pull-up resistor has its one end coupled to each of the first pre-driver stage inverters and its other end connected to a ground potential node. A shared pull-down resistor has its one end coupled to each of the second pre-driver stage inverters and its other end connected to a power supply potential node.

Abstract: A unified erase method used in an array of flash EEPROM memory cells arranged in a plurality of sectors for performing either a single-sector, multiple-sector, or all-sector erasing operation with a reduced amount of total erase time and a uniform VT distribution as good as that of a single-sector erase operation is provided. An erase-verify operation is performed sequentially on the plurality of sectors from a first sector to a last sector beginning with a first address of each sector if its corresponding erase-on signal is not turned OFF. The current address of each sector is stored at a point where the erase-verify operation failed. An erase pulse is applied only to all sectors simultaneously that have not passed the erase-verify operation. The erase-verify operation is then repeated beginning at the current address stored. The erasing operation is terminated when the erase-on signal has been turned OFF in all sectors in the plurality of sectors.

Abstract: A method and apparatus for providing a charge pump that is particularly useful for generating high voltages and high currents for erasing and programming flash electrically-erasable programmable read only memory arrays (Flash EEPROMs). The invention includes an efficient method and circuit for generating a pumped voltage with no voltage drop from one stage to the next by using a simple two-phase clocking scheme and an auxiliary pump to gate a larger primary pump. One feature allows adjustment of the level of voltage pumping to accommodate higher voltage power supplies.

Abstract: There is provided a method of correcting overerased memory cells in a flash EEPROM memory cell after erase so as to produce a narrow threshold voltage distribution width. A ground potential is applied to all of the sources and substrates of the cells in the array of memory cells. First positive pulse voltages are simultaneously applied to each word line in a first timed sequence on a word line by word line basis. A second positive pulse voltage is simultaneously applied to each bit line in a second timed sequence in a bit line by bit line basis when the first positive pulse voltages are being applied to a first word line and is then repeated for each subsequent word line until a last word line is applied.

Abstract: There is provided a method of measuring the value of the threshold voltage of a memory core cell in an array of flash EEPROM memory core cells. The memory core cell includes an array core transistor having a corresponding array threshold voltage which is to be measured. There is provided a reference current level at a constant value which is generated by a reference cell transistor having a fixed bias condition and a fixed threshold voltage so that the relationship of the bias voltage applied to its gate and the fixed threshold voltage is linear. A control gate bias voltage applied to the gate of the array core transistor having the array threshold voltage which is to be measured is varied continuously.

Abstract: The invention is a novel erase method for erasing flash EEPROM memory devices. A memory cell of such a memory device has a first semiconductor region of one conductivity type formed in a second region of the opposite conductivity type, source and drain regions of the opposite conductivity type formed in the first semiconductor region, and a gate. The second region is formed within a substrate of the one conductivity type. The gate includes a control gate and a floating gate, which retains charge and overlies the first semiconductor region. The erase method of the invention includes the steps of: applying a first voltage of one polarity to the source region and the first and second semiconductor regions; and simultaneously applying a second voltage of the opposite polarity to the gate, whereby any charge on the floating gate tunnels through the floating gate dielectric into both the first region and the source region, thereby removing any charge retained by the floating gate.