Semiconductor memory device and method for programming and erasing a memory cell
First Claim
1. A semiconductor memory device comprisinga memory cell having a variable resistive element whose electrical resistance is varied,programming means for programming data into said memory cell using the variation of the electrical resistance of said variable resistive element,programming state detection means for detecting variation in the electrical resistance at the time of programming operation carried out by said programming means, andprogramming control means for stopping the programming operation by said programming means when the electrical resistance is varied to a predetermined reference value.
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Abstract
A semiconductor memory device comprises a memory array in which memory cells having variable resistive elements (R11 to Rij) whose electrical resistance is varied by electrical stress and is held even after the electrical stress is released and selection transistors (T11 to Tij) comprising N type MOSFETs are arranged with a matrix; programming means for applying the electrical stress to the variable resistive elements (R11 to Rij) to program data into the memory cell; programming state detection means for detecting the variation in the electrical resistance at the time of the programming operation; and programming control means for stopping the application of the electrical stress when the electrical resistance is varied to a predetermined reference value. With this structure, it is possible to constitute the semiconductor memory device in which the time required for programming data is shortened and the programming precision is high.
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Citations
38 Claims
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1. A semiconductor memory device comprising
a memory cell having a variable resistive element whose electrical resistance is varied, programming means for programming data into said memory cell using the variation of the electrical resistance of said variable resistive element, programming state detection means for detecting variation in the electrical resistance at the time of programming operation carried out by said programming means, and programming control means for stopping the programming operation by said programming means when the electrical resistance is varied to a predetermined reference value.
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12. A semiconductor memory device comprising
a memory cell having a variable resistive element whose electrical resistance is varied by electrical stress and is held even after the electrical resistance is released, programming means for programming data into said memory cell by applying the electrical stress to said variable resistive element to vary the electrical resistance, programming state detection means for detecting variation of said electrical resistance at the time of programming operation by said programming means, and programming control means for stopping application of the electrical stress by said programming means when the electrical resistance is varied to a predetermined reference value.
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23. A semiconductor memory device comprising
a memory cell having a variable resistive element whose electrical resistance is varied, erasing means for erasing data from said memory cell using variation of the electrical resistance of said variable resistive element, erasing state detecting means for detecting variation of the electrical resistance at the time of erasing operation by said erasing means, and erasing control means for stopping the erasing operation by said erasing means when the electrical resistance is varied to a predetermined second reference value.
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29. A semiconductor memory device comprising
a memory cell having a variable resistive element whose electrical resistance is held even after the electrical resistance is varied by electrical stress and the electrical stress is released, erasing means for erasing data from said memory cell by applying the electrical stress to said variable resistive element to vary the electrical resistance, erasing state detecting means for detecting variation of the electrical resistance at the time of erasing operation by said erasing means, and erasing control means for stopping application of the electrical stress by said erasing means when the electrical resistance is varied to a predetermined second reference value.
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35. A programming method into a memory cell, wherein
said memory cell includes a variable resistive element whose electrical resistance is varied, a programming operation for programming data into said memory cell using variation of the electrical resistance and a detecting operation for detecting variation of the electrical resistance of said memory cell at the time of the programming operation are carried out simultaneously, the programming operation is carried out until the electrical resistance reaches a predetermined reference value.
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36. A programming method into a memory cell, wherein
said memory cell includes a variable resistive element whose electrical resistance is varied by electrical stress and is held even after the electrical stress is released, a programming operation for programming data into said memory cell by applying the electrical stress to said variable resistive element to vary the electrical resistance and a detecting operation for detecting variation of the electrical resistance of said memory cell at the time of programming operation are carried out simultaneously, the application of the electrical stress is stopped when the electrical resistance is varied to a predetermined reference value.
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37. An erasing method from a memory cell, wherein
said memory cell includes a variable resistive element whose electrical resistance is varied, an erasing operation for erasing data from said memory cell is carried out using the variation of the electrical resistance, a detecting operation for detecting the electrical resistance of said memory cell at the time of the erasing operation is carried out simultaneously with said erasing operation, said erasing operation is carried out until it is detected that the electrical resistance reaches a predetermined reference value.
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38. An erasing method from a memory cell, wherein
said memory cell includes a variable resistive element whose electrical resistance is varied by electrical stress and is held even after the electrical stress is released, an erasing operation for erasing data from said memory cell is carried out by applying the electrical stress to said variable resistive element to vary the electrical resistance, a detecting operation for detecting variation of the electrical resistance of said memory cell at the time of the erasing operation, said detecting operation and said erasing operation are carried out simultaneously, the application of the electrical stress is stopped when the electrical resistance is varied to a predetermined second reference value.
Specification