Articles you may be interested inInvestigation of thermal resistance and power consumption in Ga-doped indium oxide (In2O3) nanowire phase change random access memory Appl. Phys. Lett.A self-aligned process for phase-change material nanowire confined within metal electrode nanogap

A phase-change random access memory (PCRAM) geometric model is proposed to improve the thermal efficiency. A low-κ layer with very low thermal conductivity is inserted into the insulation layer. Then, the effective programming area and the programming current are greatly reduced. In addition, the selection conditions for the low-κ layer are carefully studied to help us find a suitable material that can be used as a low-κ layer. It is believed that this simple geometric model is a useful tool for increasing the thermal efficiency of PCRAM devices and for selecting the appropriate conditions for a low-κ layer allowing low-current operation.

A lithography-independent and wafer scale method to fabricate a metal nanogap structure is demonstrated. Polysilicon was first dry etched using photoresist (PR) as the etch mask patterned by photolithography. Then, by depositing conformal SiO2 on the polysilicon pattern, etching back SiO2 anisotropically in the perpendicular direction and removing the polysilicon with KOH, a sacrificial SiO2 spacer was obtained. Finally, after metal evaporation and lifting-off of the SiO2 spacer, an 82 nm metal-gap structure was achieved. The size of the nanogap is not determined by the photolithography, but by the thickness of the SiO2. The method reported in this paper is compatible with modern semiconductor technology and can be used in mass production.

An electroless deposition (ELD) method is introduced to fabricate a metal nanoplug for its advantages of simplicity, low cost and auto-selectivity. It was demonstrated that nanoplugs of less than 50 nm in diameter can be fabricated by ELD nickel on various substrates, such as silicon, tungsten and titanium nitride. The main composition of the ELD nanoplug was characterized as nickel by an energy dispersive X-ray microanalyzer. A functional vertical phase-change random access memory (PCRAM) device with a heater diameter of around 9 m was fabricated by using the ELD method. The I -V characteristics demonstrated that the threshold current is only 90.8 A. This showed that the ELD process can satisfy the demands of PCRAM device application, as well as device performance improvement. The ELD process provides a promising method for the simple and low-cost fabrication of metal nanoplugs.