Abstract: A nonvolatile semiconductor memory device includes a memory cell array for storing user data provided by arranging memory cells each having a variable resistive element having a first electrode, a second electrode, and a variable resistor made of a metal oxide sandwiched between the first and second electrodes. The first and second electrodes are formed of a conductive material forming ohmic junction with the variable resistor and a conductive material forming non-ohmic junction with the variable resistor, respectively. The variable resistor changes between two or more different resistance states by applying a voltage between the electrodes. The resistance state after being changed is maintained in a nonvolatile manner. The variable resistive elements of all memory cells in the memory cell array are set to the highest of the two or more different resistance states in an unused state before the memory cell array is used to store the user data.

Abstract: Provided is a semiconductor memory device that is capable of stably programming with desirable controllability to a desired electric resistance state in a random access programming action and is provided with a variable resistance element. Regardless of a resistance state of a variable resistance element of a memory cell that is a target of a writing action (erasing and programming actions), an erasing voltage pulse for bringing the resistance state of the variable resistance element to an erased state having a lowest resistance value is applied. Thereafter, a programming voltage pulse for bringing the resistance state of the variable resistance element to a desired programmed state is applied to the variable resistance element of the programming action target memory cell. By always applying the programming voltage pulse after having applied the erasing voltage pulse, a plurality of programming voltage pulses being sequentially applied can be avoided.

Abstract: Regardless of a resistance state of a variable resistance element of a memory cell that is a target of a writing action (erasing and programming actions), an erasing voltage pulse for bringing the resistance state of the variable resistance element to an erased state having a lowest resistance value is applied. Thereafter, a programming voltage pulse for bringing the resistance state of the variable resistance element to a desired programmed state is applied to the variable resistance element of the programming action target memory cell. By always applying the programming voltage pulse after having applied the erasing voltage pulse, a plurality of programming voltage pulses being sequentially applied can be avoided. Further, the memory cell array is constituted of even-numbers of subbanks, and the application of the erasing voltage pulse in one subbank and the application of the programming voltage pulse in the other subbank are alternately performed.

Abstract: A variable resistance element that can stably perform a switching operation with a property variation being reduced by suppressing a sharp current that accompanies completion of forming process, and a non-volatile semiconductor memory device including the variable resistance element are realized. The non-volatile semiconductor memory device uses the variable resistance element for storing information in which a resistance changing layer is interposed between a first electrode and a second electrode, and a buffer layer is inserted between the first electrode and the resistance changing layer where a switching interface is formed. The buffer layer and the resistance changing layer include n-type metal oxides, and materials of the buffer layer and the resistance changing layer are selected such that energy at a bottom of a conduction band of the n-type metal oxide configuring the buffer layer is lower than that of the n-type metal oxide configuring the resistance changing layer.

Abstract: A semiconductor memory device includes a memory cell array where a plurality of memory cells are arranged in a matrix, each of the memory cells serially connecting a two-terminal type memory element and a transistor for selection, a first voltage applying circuit that applies a write voltage pulse to a bit line, and a second voltage applying circuit that applies a precharge voltage to a bit line and a common line. In writing the memory cell, after the second voltage applying circuit has both terminals of the memory cell previously precharged to the same voltage, the first voltage applying circuit applies the write voltage pulse to one terminal of the writing target memory cell via the bit line, and while the write voltage pulse is applied, the second voltage applying circuit maintains the application of the precharge voltage to the other terminal of the memory cell via the common line.

Abstract: A semiconductor memory device having a cross point structure includes a plurality of upper electrodes arranged to extend in one direction, and a plurality of lower electrodes arranged to extend in another direction at a right angle to the one direction of the upper electrodes. Memory materials are provided between the upper electrodes and the lower electrodes for storage of data. The memory materials are made of a perovskite material and arranged at the lower electrodes side of the corresponding upper electrode extending along the corresponding upper electrode.

Abstract: A nonvolatile semiconductor memory device includes a bit voltage adjusting circuit which, for each bit line, fixes potentials of a selected bit line and a non-selected bit line to a predetermined potential to perform a memory operation and a data voltage adjusting circuit which, for each data line, fixes potentials of a selected data line and a non-selected data line to a predetermined potential to perform a memory operation. Each of the voltage adjusting circuits includes an operational amplifier and a transistor, a voltage required for a memory operation is input to the non-inverted input terminal of the operational amplifier, and the inverted input terminal of the operational amplifier is connected to the bit line or the data line, so that the potential of the bit line or the data line is fixed to a potential of the non-inverted input terminal of the operational amplifier.

Abstract: A nonvolatile semiconductor memory device include: a two terminal structured variable resistive element, wherein resistive characteristics defined by current-voltage characteristics at both ends transit between low and high resistance states stably by applying a voltage satisfying predetermined conditions to the both ends. A transition from the low resistance state to the high resistance state occurs by applying a voltage of a first polarity whose absolute value is at or higher than first threshold voltage, and the reverse transition occurs by applying a voltage of a second polarity whose absolute value is at or higher than a second threshold voltage. A load circuit is connected to the variable resistive element in series having an adjustable load resistance. A voltage generation circuit applies a voltage to both ends of a serial circuit. The variable resistive element can transit between the states by adjusting a resistance of the load circuit.

Abstract: A semiconductor memory device having a cross point structure includes a plurality of upper electrodes arranged to extend in one direction, and a plurality of lower electrodes arranged to extend in another direction at a right angle to the one direction of the upper electrodes. Memory materials are provided between the upper electrodes and the lower electrodes for storage of data. The memory materials are made of a perovskite material and arranged at the lower electrodes side of the corresponding upper electrode extending along the corresponding upper electrode.

Abstract: A semiconductor memory device having a cross point structure includes a plurality of upper electrodes arranged to extend in one direction, and a plurality of lower electrodes arranged to extend in another direction at a right angle to the one direction of the upper electrodes. Memory materials are provided between the upper electrodes and the lower electrodes for storage of data. The memory materials are made of a perovskite material and arranged at the lower electrodes side of the corresponding upper electrode extending along the corresponding upper electrode.

Abstract: A manufacturing method for a variable resistive element according to which a stable switching operation can be achieved with excellent reproducibility is provided. A conductive thin film is deposited on a semiconductor substrate and patterned to a predetermined form, and after that, a first interlayer insulating film is deposited. An opening is then created in a predetermined location on the first interlayer insulating film in such a manner that the upper surface of the conductive thin film is exposed and the thickness of the conductive thin film formed at the bottom of this opening is reduced through processing, and after that, an oxidation process is carried out on the periphery of the exposed conductive thin film. As a result, a variable resistor film is formed in the peripheral region of the opening, and this variable resistor film divides the conductive thin film into a first electrode and a second electrode.

Abstract: A nonvolatile semiconductor memory device comprises: a two terminal structured variable resistive element, wherein resistive characteristics defined by current-voltage characteristics at both ends transit between low and high resistance states stably by applying a voltage satisfying predetermined conditions to the both ends, a transition from the low resistance state to the high resistance state occurs by applying a voltage of a first polarity whose absolute value is at or higher than a first threshold voltage, and the reverse transition occurs by applying a voltage of a second polarity whose absolute value is at or higher than a second threshold voltage; a load circuit connected to the variable resistive element in series having an adjustable load resistance; and a voltage generation circuit for applying a voltage to both ends of a serial circuit; wherein the variable resistive element can transit between the states by adjusting a resistance of the load circuit.

Abstract: A semiconductor memory device comprising a variable resistance element having a variable resistor between a first electrode and a second electrode, in which electric resistance is changed by applying a voltage pulse between the electrodes comprises at least one reaction preventing film made of a material having an action of blocking the permeation of a reduction species promoting a reduction reaction of the variable resistor and an oxidation species promoting an oxidation reaction of the variable resistor. This prevents the resistance value of the variable resistance element from fluctuating due to a reduction reaction or an oxidation reaction of the variable resistor caused by hydrogen or oxygen existing in the manufacturing steps, so that a semiconductor memory device having a small variation of the resistance value and having a good controllability can be realized with good repeatability.

Abstract: The present invention is directed towards a method of manufacturing a semiconductor memory device arranged of a cross point memory array having memory elements provided between upper and lower electrodes for storage of data. The present invention comprises a lower electrode lines forming step of planarizing each of the lower electrode lines and insulating layers provided on both sides of the lower electrode line so as to be substantially uniform in the height thus for patterning the lower electrode lines, a memory element layer depositing step of depositing on the lower electrode lines a memory element layer for the memory elements, and an annealing step of annealing with heat treatment either between the lower electrode lines forming step and the memory element layer depositing step or after the memory element layer depositing step so that any damages caused by the polishing of the surface of the lower electrode lines can be eliminated.

Abstract: A semiconductor memory device having a cross point structure includes a plurality of upper electrodes arranged to extend in one direction, and a plurality of lower electrodes arranged to extend in another direction at a right angle to the one direction of the upper electrodes. Memory materials are provided between the upper electrodes and the lower electrodes for storage of data. The memory materials are made of a perovskite material and arranged at the lower electrodes side of the corresponding upper electrode extending along the corresponding upper electrode.

Abstract: A contact plug electrically connected with a MOS transistor is formed in a first interlayer dielectric. Then, a barrier metal material is deposited over the first interlayer dielectric and the contact plug, and patterned into a barrier metal electrically connected with the contact plug. After a SiN film is formed as an anti-oxygen-permeation film over the barrier metal and the first interlayer dielectric, the film is abraded by a chemical mechanical polishing technique until a top surface of the barrier metal is exposed. Then, a lower electrode material, a dielectric material and an upper electrode material are deposited in this order on the SiN film and the barrier metal, and then patterned such that a resulting lower electrode covers at least the entire upper surface of the barrier metal. Thereafter a second interlayer dielectric is deposited, and a heat treatment is performed in an oxygen ambient to recover film quality of a capacitor dielectric.

Abstract: A contact plug electrically connected with a MOS transistor is formed in a first interlayer dielectric. Then, a barrier metal material is deposited over the first interlayer dielectric and the contact plug, and patterned into a barrier metal electrically connected with the contact plug. After a SiN film is formed as an anti-oxygen-permeation film over the barrier metal and the first interlayer dielectric, the film is abraded by a chemical mechanical polishing technique until a top surface of the barrier metal is exposed. Then, a lower electrode material, a dielectric material and an upper electrode material are deposited in this order on the SiN film and the barrier metal, and then patterned such that a resulting lower electrode covers at least the entire upper surface of the barrier metal. Thereafter a second interlayer dielectric is deposited, and a heat treatment is performed in an oxygen ambient to recover film quality of a capacitor dielectric.

Abstract: A semiconductor device has a diffusion layer formed on a silicon substrate, an interlayer insulator which covers a surface of the silicon substrate and whose surface is planarized, and a dielectric capacitor composed of a lower electrode connected to the diffusion layer via a buried conductive layer which is buried within a contact hole opened in the interlayer insulator and which is formed of a barrier metal layer composed of a contact plug, a low resistance layer and tantalum silicon nitride, and a dielectric film formed on the lower electrode, and an upper electrode. The lower electrode has a side-wall sloped configuration that its cross-sectional area monotonously increases from the buried conductive layer side toward the. upper dielectric film. Thus, a high-integration semiconductor device which allows the lower electrode to be micro-fabricated and enables lower-voltage operation and higher reliability can be obtained.

Abstract: A semiconductor device has a diffusion layer formed on a silicon substrate, an interlayer insulator which covers a surface of the silicon substrate and whose surface is planarized, and a dielectric capacitor composed of a lower electrode connected to the diffusion layer via a buried conductive layer which is buried within a contact hole opened in the interlayer insulator and which is formed of a barrier metal layer composed of a contact plug, a low resistance layer and tantalum silicon nitride, and a dielectric film formed on the lower electrode, and an upper electrode. The lower electrode has a side-wall sloped configuration that its cross-sectional area monotonously increases from the buried conductive layer side toward the upper dielectric film. Thus, a high-integration semiconductor device which allows the lower electrode to be micro-fabricated and enables lower-voltage operation and higher reliability can be obtained.

Abstract: After forming a capacitor of a stack type ferroelectric memory device by sequentially patterning an upper electrode, a ferroelectric film and a lower electrode formed above an interlayer insulator film, the capacitor is covered with an oxidation barrier layer. After forming the oxidation barrier layer, the in-process memory device is heat treated at a high temperature in an oxygen-containing atmosphere. The oxidation barrier layer prevents the lower electrode of the capacitor and a barrier metal film between the capacitor and the interlayer insulator film from oxidation during heat treatment. Thus, the occurrence of peelings and hillocks in the lower electrode and the barrier metal film is avoided so that a semiconductor memory has good electrical characteristics and high reliability.