摘要:
To provide a variable resistance element writing method that, even when a variable resistance element has a possibility of becoming a half LR state, can ensure a maximum resistance change window by correcting the variable resistance element to a normal low resistance state. In a method of writing data to a variable resistance element (10a) that reversibly changes between a high resistance state and a low resistance state according to a polarity of an applied voltage, as a voltage applied to an upper electrode (11) with respect to a lower electrode (14t): a positive voltage is applied in a high resistance writing step (405) to set the variable resistance element (10a) to a high resistance state (401); a negative voltage is applied in a low resistance writing step (406, 408) to set the variable resistance element (10a) to a low resistance state (403, 402); and a positive voltage is applied in a low resistance stabilization writing step (404) after the negative voltage is applied in the low resistance writing step (408), thereby setting the variable resistance element (10a) through the low resistance state to the high resistance state (401).
摘要:
A writing method optimum for a variable resistance element which can maximize an operation window of the variable resistance element is provided. The writing method is performed for a variable resistance element that reversibly changes between a high resistance state and a low resistance state depending on a polarity of an applied voltage pulse. The writing method includes a preparation step (S50) and a writing step (S51, S51a, S51b). At the preparation step (S50), resistance values of the variable resistance element are measured by applying voltage pulses of voltages that are gradually increased to the variable resistance element, thereby determining the first voltage V1 for starting high resistance writing and the second voltage V2 having a maximum resistance value. At the HR writing step (S51a), a voltage pulse having a voltage Vp that is equal to or higher than the first voltage V1 and equal to or lower than the second voltage V2 is applied to the variable resistance element, thereby changing the variable resistance element from the low resistance state (S52) to the high resistance state (S53).
摘要:
A method of writing data to a variable resistance element (10a) that reversibly changes between a high resistance state and a low resistance state according to a polarity of an applied voltage, as a voltage applied to an upper electrode (11) with respect to a lower electrode (14t): a positive voltage is applied in a high resistance writing step (405) to set the variable resistance element to a high resistance state (401); a negative voltage is applied in a low resistance writing step (406, 408) to set the variable resistance element to a low resistance state (403, 402); and a positive voltage is applied in a low resistance stabilization writing step (404) after the negative voltage is applied in the low resistance writing step, thereby setting the variable resistance element through the low resistance state to the high resistance state.
摘要:
A method of writing data to a variable resistance element (10a) that reversibly changes between a high resistance state and a low resistance state according to a polarity of an applied voltage, as a voltage applied to an upper electrode (11) with respect to a lower electrode (14t): a positive voltage is applied in a high resistance writing step (405) to set the variable resistance element to a high resistance state (401); a negative voltage is applied in a low resistance writing step (406, 408) to set the variable resistance element to a low resistance state (403, 402); and a positive voltage is applied in a low resistance stabilization writing step (404) after the negative voltage is applied in the low resistance writing step, thereby setting the variable resistance element through the low resistance state to the high resistance state.
摘要:
To provide a variable resistance element writing method that, even when a variable resistance element has a possibility of becoming a half LR state, can ensure a maximum resistance change window by correcting the variable resistance element to a normal low resistance state. In a method of writing data to a variable resistance element (10a) that reversibly changes between a high resistance state and a low resistance state according to a polarity of an applied voltage, as a voltage applied to an upper electrode (11) with respect to a lower electrode (14t): a positive voltage is applied in a high resistance writing step (405) to set the variable resistance element (10a) to a high resistance state (401); a negative voltage is applied in a low resistance writing step (406, 408) to set the variable resistance element (10a) to a low resistance state (403, 402); and a positive voltage is applied in a low resistance stabilization writing step (404) after the negative voltage is applied in the low resistance writing step (408), thereby setting the variable resistance element (10a) through the low resistance state to the high resistance state (401).
摘要:
An optimum forming method of performing a forming for a variable resistance element to maximize an operation window of the variable resistance element is provided. The forming method is used to initialize a variable resistance element (100). The forming method includes: a determination step (S35) of determining whether or not a current resistance value of the variable resistance element (100) is lower than a resistance value in a high resistance state; and a voltage application step (S36) of applying a voltage pulse having a voltage not exceeding a sum of a forming voltage and a forming margin when the determination is made that the current resistance value is not lower than the resistance value in the high resistance state (No at S35). The determination step (S35) and the voltage application step (S36) are repeated to process all memory cells in a memory array (202) (S34 to S37).
摘要:
An optimum forming method of performing a forming for a variable resistance element to maximize an operation window of the variable resistance element is provided. The forming method is used to initialize a variable resistance element (100). The forming method includes: a determination step (S35) of determining whether or not a current resistance value of the variable resistance element (100) is lower than a resistance value in a high resistance state; and a voltage application step (S36) of applying a voltage pulse having a voltage not exceeding a sum of a forming voltage and a forming margin when the determination is made that the current resistance value is not lower than the resistance value in the high resistance state (No at S35). The determination step (S35) and the voltage application step (S36) are repeated to process all memory cells in a memory array (202) (S34 to S37).
摘要:
A writing method optimum for a variable resistance element which can maximize an operation window of the variable resistance element is provided. The writing method is performed for a variable resistance element that reversibly changes between a high resistance state and a low resistance state depending on a polarity of an applied voltage pulse. The writing method includes a preparation step (S50) and a writing step (S51, S51a, S51b). At the preparation step (S50), resistance values of the variable resistance element are measured by applying voltage pulses of voltages that are gradually increased to the variable resistance element, thereby determining the first voltage V1 for starting high resistance writing and the second voltage V2 having a maximum resistance value. At the HR writing step (S51a), a voltage pulse having a voltage Vp that is equal to or higher than the first voltage V1 and equal to or lower than the second voltage V2 is applied to the variable resistance element, thereby changing the variable resistance element from the low resistance state (S52) to the high resistance state (S53).
摘要:
Provided is a nonvolatile storage device (200) capable of stably operating without increasing a size of a selection transistor included in each of memory cells. The nonvolatile storage device (200) includes: a semiconductor substrate (301) which has a P-type well (301a) of a first conductivity type; a memory cell array (202) which includes memory cells (M11) or the like each of which includes a variable resistance element (R11) and a transistor (N11) that are formed above the semiconductor substrate (301) and connected in series; and a substrate bias circuit (220) which applies, to the P-type well (301a), a bias voltage in a forward direction with respect to a source and a drain of the transistor (N11), when a voltage pulse for writing is applied to the variable resistance element (R11) included in the selected memory cell (M11) or the like.
摘要:
In forming, an automatic forming circuit (210) included in a nonvolatile memory device (200) causes a constant current IL to flow in a selected memory cell having a considerably high initial resistance. When the forming generates a filament path in the memory cell and thereby a resistance value is decreased, a potential of a node NBL and a potential of a node Nin are also decreased. If the potentials become lower than that of a reference voltage Vref, an output NO of a difference amplifier (303) for detecting forming success is activated, and a forming success signal Vfp is activated after a delay time depending on the number n of flip flops FF1 to FFn and a clock signal CLK. Thereby, a switch transistor (301) is in a non-conducting state and the forming on a variable resistance element is automatically terminated.