Operation Method Optimization Of Resistive Switching Memory Based On Metal Oxide

Nowadays,the demand for semiconductor memory is increasing.The traditional flash memory faces the physical bottleneck of the size scalability.As the size of the device decreases,the problem of crosstalk and the decline of the charge retention performance are highlighted.Therefore,it is an inevitable trend to develop a new type of memory technology.The resistive random access memory has the advantages of simple structure,compatibility with CMOS process,excellent scalability,low operation voltage,low power consumption,fast switching speed,feasibility for 3D integration and so on.It will become a strong competitor of the next generation of new non-volatile memory.However,resistive random access memories are also faced with many problems when used as large-scale storage applications,such as the uniformity of operating voltage and resistance is poor and slow switching speed when using verify operation methods.We can improve these issues from multiple perspectives,such as material systems,manufacturing processes,and operating methods.To solve these problems,this paper mainly optimizes the uniformity and switching speed from the operating methods.In this paper,the operating methods of the single device and array with TiN/HfO_x/TaO_x/TiN material systems are optimized.In order to optimize the uniformity of the resistive memory under low current,we first proposed a current and voltage joint verification strategy.The current and voltage joint verification strategy is different from the traditional incremental step pulse programming method.The traditional ISPP method control the conductive filaments only by changing the voltage.In the current and voltage joint verification strategy,the electric field and current compliance(current compliance,CC)jointly control the conductive filaments of the resistive random access memory,therefore,it greatly improves the uniformity of the resistance.Based on the current and voltage joint verification strategy,7 different resistance states are obtained,which improves the multilevel storage capability of the resistive random access memory.Since there is tradeoff between switching speed and uniformity,we need to consider uniformity when improving switching speed.Therefore,in order to improve the switching speed of the resistive random access memory,we proposed a verify operation method in which the switching speed and uniformity are cooperatively optimized.The new verification method is mainly improved from three aspects,namely,the verification number,the pulse amplitude and the step,and the pulse width.The test results under three kinds of different pulse widths show that multiple short pulses are better than a long pulse with the same length.For the memory of the TiN/HfO_x/TaO_x/TiN material system,the SET process needs 3 pulses at most and the over programming bit rate is 7%under the excitation of the 10ns pulse.The RESET process needs 4 pulses at most,which improves the switching speed of the resistive random access memory greatly,and the tradeoff between the switching speed and uniformity is achieved.