Structure of phase change memory cell and implementation method thereof

Abstract

The invention relates to a block construction of a phase change memory and an implementation method thereof, comprising an underlay, a bottom layer electrode, a transition layer, a heat insulating layer, a phase-change material layer, a transition layer, a tungsten electrode and a top electrode. The structure is characterized in that a hollow groove which is etched by the exposure etching technology is arranged in the tungsten electrode under the phase-change material layer; the hollow groove is filled with heat insulating material SiO2 to reduce a contact surface of a hot part, thereby reducing crystal region volume; the inside radius of the hollow groove-shaped tungsten electrode is more than 0.4 times as long as the outer radius of the hollow groove-shaped tungsten electrode. When current of the phase-change material layer is heavier than threshold current, the phase-change material switches from non-crystal phase to crystal phase. A hollow structure is adopted in the tungsten electrode, thereby increasing the resistance difference between an initial crystallization state and a complete crystallization state, thus realizing more intermediary resistance states between two steady crystallization states by different operating currents and improving storage capacity of the phase-change memory.

Description

technical field [0001] The invention relates to a structure and a realization method of a phase-change memory unit, and relates to a nanometer material manufacturing process in microelectronics. Background technique [0002] Compared with the current dynamic random access memory (DRAM) and flash memory (FLASH), phase change random access memory (PRAM) has obvious advantages: small size, low driving voltage, low power consumption, fast read and write speed, and non-volatile. PRAM may also be made into multi-level memory and suitable for extreme temperature environments. Because of its radiation resistance and vibration resistance, it is not only used in daily portable electronic products, but also has great potential application prospects in aerospace and other fields. In 2001, the International Semiconductor Federation predicted PRAM as one of the first memories that could be commercialized. [0003] One of the key issues in the current phase change memory research is how t...

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Problems solved by technology

On the one hand, it is to reduce the cell size, but with the reduction of the cell size, the quantum effect becomes the bottleneck to increase the number of storage cells per unit area. Another way is to realize multiple resistance states by manipulating the current or through a multi-layer phase change material composite film. , that is to change the original storage unit can only record "0, 1", realize a unit can record a variety of signals "0, 1, 2, 3..." such as Journal of The Electrochemical Society, 154 12 H999-H1003 (2007) ; In the literature J.Maimon and E.Spall, "Chalcogenide-based non-volatile memory technology," Aerospace Conference, 2001, IEEE Proc., vol.5, pp.2289-2294, March 2001. The crystalline phase change material gradually crystallizes. Although different resistance states are obtained, due to the instability of its crystallization state, a slight change in the read current will cause a change in the crystallization state. Therefore, how to obtain stable multiple resistance states becomes a problem. extremely critical

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