Patent application number | Description | Published |
20080303016 | PHASE CHANGE MEMORY DEVICES EMPLOYING CELL DIODES AND METHODS OF FABRICATING THE SAME - Phase change memory devices having cell diodes and related methods are provided, where the phase change memory devices include a semiconductor substrate of a first conductivity type and a plurality of parallel word lines disposed on the semiconductor substrate, the word lines have a second conductivity type different from the first conductivity type and have substantially flat top surfaces, a plurality of first semiconductor patterns are one-dimensionally arrayed on each word line along a length direction of the word line, the first semiconductor patterns have the first conductivity type or the second conductivity type, second semiconductor patterns having the first conductivity type are stacked on the first semiconductor patterns, an insulating layer is provided on the substrate having the second semiconductor patterns, the insulating layer fills gap regions between the word lines, gap regions between the first semiconductor patterns and gap regions between the second semiconductor patterns, a plurality of phase change material patterns are two-dimensionally arrayed on the insulating layer, and the phase change material patterns are electrically connected to the second semiconductor patterns, respectively. | 12-11-2008 |
20090040819 | NONVOLATILE MEMORY DEVICE USING RESISTIVE ELEMENTS AND AN ASSOCIATED DRIVING METHOD - A nonvolatile memory device is configured to increase the reliability of a write operation by providing a sufficiently high write current while reducing current consumption in a read operation. The nonvolatile memory device includes a memory cell array having a plurality of nonvolatile memory cells. A global bit line and a local bit line coupled to a plurality of the nonvolatile memory cells. The local bit line has first and second nodes. First and second bit line selection circuits are included where the first bit line selection circuit is coupled to the first node of the local bit line and the second bit line selection circuit is coupled to the second node of the local bit line. The first and second bit line selection circuits operate during a first period to electrically connect the local bit line to the global bit line, and only one of the first and second bit line selection circuits operates during a second period to electrically connect the local bit line to the global bit line. | 02-12-2009 |
20090122593 | Write driver circuit for phase-change memory, memory including the same, and associated methods - A write driver circuit for a memory that includes phase-change memory cells changeable between a RESET state resistance and a SET state resistance in response to an applied current pulse, the write driver circuit including a write current level adjusting unit configured to determine first to n-th SET state current levels in response to a SET state current level signal, where n is an integer greater than 1, and configured to determine a RESET state current level in response to a RESET state current level signal, and a write current output unit configured to generate one of a SET state current pulse and a RESET state current pulse corresponding to a SET state current level or a RESET state current level determined by the write current level adjusting unit. | 05-14-2009 |
20090122601 | POWER SUPPLYING CIRCUIT AND PHASE-CHANGE RANDOM ACCESS MEMORY INCLUDING THE SAME - Embodiments of the invention provide a power supplying circuit (PSC) and a phase-change random access memory (PRAM) including the PSC. According to an aspect of the invention, the PSC includes: a first voltage generator configured to output a first voltage to a first terminal; and a second voltage generator configured to output a second voltage to a second terminal, the second voltage generator including: a voltage pump unit configured to output the second voltage based on a clock signal and a pump control signal; a pump output detector coupled to the voltage pump unit, the pump output detector configured to output a pump output detection signal; and a discharging unit coupled to the voltage pump unit, the discharging unit configured to discharge a level of the second voltage to a predetermined level in response to a discharge signal. Embodiments of the invention may prevent write and/or read malfunctions that can occur due to changes in the level of a voltage supplied to PRAM cell blocks. | 05-14-2009 |
20090168493 | SEMICONDUCTOR MEMORY DEVICE WITH STACKED MEMORY CELL AND METHOD OF MANUFACTURING THE STACKED MEMORY CELL - In a semiconductor memory device and method, resistive-change memory cells are provided, each including a plurality of control transistors formed on different layers and variable resistance devices comprising a resistive-change memory. Each resistive-change memory cell includes a plurality of control transistors formed on different layers, and a variable resistance device formed of a resistive-change memory. In one example, the number of the control transistors is two. The semiconductor memory device includes a global bit line; a plurality of local bit lines connected to or disconnected from the global bit line via local bit line selection circuits which correspond to the local bit lines, respectively; and a plurality of resistive-change memory cell groups storing data while being connected to the local bit lines, respectively. Each of the resistive-change memory cells of each of the resistive-change memory cell groups comprises a plurality of control transistors formed on different layers, and a variable resistance device formed of a resistive-change memory. In addition, the semiconductor memory device has a hierarchical bit line structure that uses a global bit line and local bit lines. Accordingly, it is possible to increase both the integration density of the semiconductor memory device and the amount of current flowing through each of the resistive-change memory cells. | 07-02-2009 |
20090213646 | Phase-change random access memories capable of suppressing coupling noise during read-while-write operation - A semiconductor memory device includes at least one write global bit line connected to a plurality of local bit lines and at least one read global bit line connected to the local bit lines. The phase-change memory device having the write global bit line and the read global bit line suppress coupling noise generated during a read-while-write operation. | 08-27-2009 |
20090213647 | Phase-change random access memory capable of reducing word line resistance - A phase-change random access memory (PRAM) device capable of reducing a resistance of a word line may include a plurality of main word lines of a semiconductor memory device or PRAM bent n times in a layer different from a layer in which a plurality of sub-word lines are disposed. The semiconductor memory device or PRAM may further include jump contacts for connecting the plurality of cut sub-word lines. In a PRAM device including the plurality of main word lines and the plurality of sub-word lines being in different layers, the number of jump contacts for connecting the plurality of main word lines to a transistor of a sub-word line decoder is the same in each sub-word line or the plurality of main word lines are bent several times so that a parasitic resistance on a word line and power consumption may be reduced, and a sensing margin may be increased. | 08-27-2009 |
20090316474 | Phase change memory - The phase change memory device includes a plurality of memory banks, a plurality of local conductor lines connected to the plurality of memory banks, at least one global conductor line connected to the plurality of local conductor lines, and at least one repair control circuit configured to selectively replace at least one of the at least one global conductor line with at least one redundant global conductor line and configured to selectively replace at least one of the plurality of local conductor lines with at least one redundant local conductor line. | 12-24-2009 |
20100015785 | Method for reducing a reset current for resetting a portion of a phase change material in a memory cell of a phase change memory device and the phase change memory device - According to one embodiment, at least a portion of the phase change material including a first crystalline phase is converted to one of a second crystalline phase and an amorphous phase. The second crystalline phase transitions to the amorphous phase more easily than the first crystalline phase. For example, the first crystalline phase may be a hexagonal closed packed structure, and the first crystalline phase may be a face centered cubic structure. | 01-21-2010 |
20100103726 | PHASE CHANGE MEMORY DEVICES AND SYSTEMS, AND RELATED PROGRAMMING METHODS - A method programs a phase change memory device. The method comprises receiving program data for selected memory cells; generating bias voltages based on reference cells; sensing read data stored in a selected memory cell by supplying the selected memory cell with verification currents determined by the bias voltages; determining whether the read data is identical to the program data; and upon determining that the program data for one or more of the selected memory cells is not identical to the corresponding read data, iteratively applying a write current to the one or more selected memory cells. | 04-29-2010 |
20100110781 | Phase change memory device generating program current and method thereof - A phase change memory device may include a memory cell array, a write driver, and/or a control unit. The memory cell array may include a plurality of memory cells. The write driver may be configured to provide a program current to the memory cell array for setting a state of a phase change material to program a selected memory cell. The write driver may be configured to provide the program current such that the program current has a plurality of steps. The control unit may be configured to receive step information for adjusting a magnitude and a width of each step of the program current during a test operation and provide the step information to the write driver during a normal operation. | 05-06-2010 |
20100118601 | PHASE CHANGE RANDOM ACCESS MEMORY DEVICE - In a phase-change random access memory (PRAM) device, a write operation is performed by applying a set pulse to failed PRAM cells. The set pulse comprises a plurality of stages sequentially decreasing from a first current magnitude to a second current magnitude. The first current magnitude or the second current magnitude varies from one write loop to another. | 05-13-2010 |
20100232218 | METHOD OF TESTING PRAM DEVICE - A method of testing PRAM devices is disclosed. The method simultaneously writes input data to a plurality of memory banks by writing set data to a first group of memory banks and writing reset data to a second group of memory banks, performs a write operation test by comparing data read from the plurality of memory banks with corresponding input data, and determines a fail cell in relation to the test results. | 09-16-2010 |
20100246248 | MEMORY CELL ARRAY BIASING METHOD AND A SEMICONDUCTOR MEMORY DEVICE - A method of biasing a memory cell array during a data writing operation and a semiconductor memory device, in which the semiconductor memory device includes: a memory cell array including a plurality of memory cells in which a first terminal of a memory cell is connected to a corresponding first line of a plurality of first lines and a second terminal of the memory cell is connected to a corresponding second line of a plurality of second lines; a bias circuit for biasing a selected second line of the second lines to a reference voltage and a non-selected second line to a first voltage; and a local word line address decoder applying the reference voltage or a pumping voltage corresponding to the first voltage to the bias circuit. | 09-30-2010 |
20110026303 | VARIABLE RESISTANCE MEMORY DEVICE AND SYSTEM THEREOF - A nonvolatile memory device comprising: a plurality of memory banks, each of which operates independently and includes a plurality of resistance memory cells, each cell including a variable resistive element having a resistance varying depending on stored data; a plurality of global bit lines, each global bit line being shared by the plurality of memory banks; a temperature compensation circuit including one or more reference cells; and a data read circuit which is electrically connected to the plurality of global bit lines and performs a read operation by supplying at least one of the resistance memory cells with a current varying according to resistances of the reference cells. | 02-03-2011 |
20110080775 | NONVOLATILE MEMORY DEVICE, STORAGE SYSTEM HAVING THE SAME, AND METHOD OF DRIVING THE NONVOLATILE MEMORY DEVICE - A nonvolatile memory device includes a memory cell array including a plurality of nonvolatile memory cells each having a resistance corresponding to one of a plurality of first resistance distributions, a temperature compensation circuit including one or more reference cells each having a resistance corresponding to one among one or more second resistance distributions, and a data read circuit including a compensation unit and a sense amplifier, the compensation unit being adapted to supply compensation current to a sensing node, an amount of the compensation current varying based on the resistance of each reference cell, and the sense amplifier being adapted to compare the level of the sensing node with a reference level and to output a comparison result. | 04-07-2011 |
20110188303 | Phase change memory device generating program current and mehtod thereof - A phase change memory device may include a memory cell array, a write driver, and/or a control unit. The memory cell array may include a plurality of memory cells. The write driver may be configured to provide a program current to the memory cell array for setting a state of a phase change material to program a selected memory cell. The write driver may be configured to provide the program current such that the program current has a plurality of steps. The control unit may be configured to receive step information for adjusting a magnitude and a width of each step of the program current during a test operation and provide the step information to the write driver during a normal operation. | 08-04-2011 |
20120039141 | VOLTAGE CONTROL METHOD AND MEMORY DEVICE USING THE SAME - A memory device is provided, which includes a plurality of global bit lines, a discharge line, a switching circuit configured to connect the plurality of global bit lines to the discharge line in response to a discharge enable signal, a first discharge circuit configured to apply a first voltage that is higher than a ground voltage to the discharge line, a precharge circuit configured to apply a precharge voltage to a selected global bit line among the plurality of global bit lines, and a second discharge circuit configured to discharge the selected global bit line to a second voltage that is higher than the ground voltage. | 02-16-2012 |
20140022831 | Semiconductor Memory Device Having Dummy Bit Line - A semiconductor memory device includes a plurality of functional bit lines, at least one dummy bit line, and a dummy bit line selection unit. The at least one dummy bit line is adjacent to an outermost bit line of the functional bit lines. The dummy bit line selection unit activates the at least one dummy bit line in response to a selection control signal of one of the plurality of functional bit lines that is not adjacent to the at least one dummy bit line. The semiconductor memory device may ensure a photo margin, so that the pattern size of the functional bit lines can be made uniform. | 01-23-2014 |