Study On Dimensional, Uniformity And Operating Polarity Of Cu_xSi_yO Resistance Memory

As device dimensions’continuing scaling down, the traditional Flash memory technology is about to reach its physical limits. Because of its simple structure, miniature, fast read and writing speeds, low power consumption, and CMOS process compatibility, and low cost, resistive memory is considered to be the most likely alternative to Flash technology. Based on novel CuxSiyO resistive memory, this paper addressed a series of hot and difficult problems of resistive memory. These problems include the scaling down capacity, the uniformity of the parameters, bipolar and unipolar operating modes.In order to prove its ability to replace NAND Flash, resistive memory’s device size is at least capable of scaling to the20nm technology generation. Based0.13um logic process we manufactured the1M bit CuxSiyO resistive memory chip, and used a spacer pattern technology to fabricate small size resistive device whose hole-size is40nm, and55nm,70nm and90nm (corresponding to22nm,32nm,45nm,65nm technology generation). The test results show that, CuxSiyO resistive memory can work properly in the22nm technology generation. The other hand, when the device size is smaller than90nm, the low-resistance state resistance as the reduction of the size of the device is increased, RESET current also reduced. For a40nm device, the RESET current is only one fifth of that of the190nm device, i.e. only30uA.Parameters inhomogeneity is one of the biggest challenges of the resistive memory. Parameters uneven cause the voltage, resistance window smaller or even disappear, and also causes the device to require a more complex algorithms and circuits to achieve operation. This paper presents a test method and test platform, which can collect data on the large-capacity resistive memory chip. We also discussed how to use physical techniques and electrical ones to detect inhomogeneities. The CuxSiyO resistive memory unevenness in initial state is caused by the uneven quality of the film and the thickness of the CuxSiyO. Further, this paper studies the CuxSiyO preparation conditions as well as the size of the array uniformity, and to optimize the process and design conditions.Resistive memory can be divided into bipolar type and unipolar type, according to whether SET/RESET operation voltage direction is the same. Bipolar type shows less SET/RESET interference and small operating current; the unipolar type shows simple operation and compatibility with the diode. Traditional CuxSiyO resistive memory can work in bipolar mode. This study found that under certain forming conditions CuxSiyO resistive memory can be stably operated in unipolar mode. The low resistance state conduction characteristics and the measurement of the resistance-temperature curve shows that:Bipolar conduction is due to the hole-conductive, and the unipolar type is conductive by the metal ion. This paper also proposed, according to the needs of different applications, CuxSiyO memory can work in bipolar and unipolar mode by controlling the operating conditions.Finally, I hope that through the study and discussion of these issues, which will deepen the understanding of the mechanism of the resistive switching, and to accelerate the applications of resistive memroy.