Impacts of post-metallization annealing on the memory performance of Ti/HfO₂-based resistive memory

Abstract

Impacts of post-metallization annealing (PMA) on bipolar resistance switching of Ti/HfO x stacked films were investigated. A Ti capping film as a scavenging layer with assistance of PMA is used to tune the dielectric strength of the 10-nm-thick HfO x layer. The polycrystalline microstructure of 10-nm-thick HfO x seems immune to the temperature of PMA in this work. The initial resistance and forming voltage in the Ti/HfO x devices mitigate as the increment of the annealing temperature. With enough annealing temperature (>450 • C), the device shows a good on/off ratio, high temperature operation ability and robust endurance (>10 6 cycles). Through the reaction between Ti and HfO x at 500 • C, the abundant oxygen ions are depleted from the insulator and the left charge-defects building conductive percolative paths in the dielectric layer. The operation-polarity independence of the form-free HfO x device in initial state is demonstrated. The forming-free memory with initial low resistance of 800 at 0.1 V can be operated with stable bipolar resistance switching via initially positive or negative voltage sweep. The formless device with 10 nm thick HfO x also exhibits excellent nonvolatile memory performances, including enough on/off ratio, improved HRS uniformity and good high temperature retention (3 × 10 4 s at 200 • C). The results of this work suggest that the PMA temperature will affect the memory window and cycling reliability of the Ti/HfO x -based resistive memory. Optimum temperature (450 • C) will improve the memory performance of the Ti/HfO x stacked layer.

Impact of inserted Ta ultrathin layer and postdeposition annealing on the forming voltage of Ir/Ti/Ta/HfO2/TiN/Ti/SiO2/Si resistive switching devices

“…It is known that when the density of oxygen vacancies in the HfO x layer increases the forming voltage of the HfO x -based RS device decreases. 13,23,24) The decrease in the forming voltage of device-C indicates that the oxygen atoms inside the HfO 2 layer migrate to the Ti scavenging layer.…”

Effects of Ambient and Annealing Temperature in HfO2 Based RRAM Device Modeling and Circuit-Level Implementation

“…Resistive switching effect is identified in various transition metal oxides, especially Ta 2 O 5 , TiO 2 , ZrO 2 , CeO 2 and HfO 2 .In that, a high dielectric constant (∼21) HfO 2 based RRAM performs excellent switching and reliability, due to its high band gap energy (5.6 eV), low leakage current and excellent compatibility with a conventional CMOS processing technology. 17,[23][24][25][31][32][33] Considering these uniqueness of the HfO 2 material, the proposed memory cell is designed with a 30 nm HfO 2 as a switching layer.…”

“…As will be shown in the following sections, the role played by temperature is of the utmost importance in understanding the electrical behavior of RRAMs, a problem already recognized by several authors. [22][23][24][25] The study of the role played by the annealing temperature within the RRAM models is particularly carried out for the SFM because its use is extensive and its algebraic formulation is both compact and intuitive. For more development, it should be noted that in recent years the modeling of voltage controlled model devices has been approached using a variety of approaches; 12,14,[16][17][18] in particular, different types of filament shapes have been considered (cylindrical, truncated by and, and hourglass).…”

Experimental optimization of post metal annealing on fully depleted-silicon on insulator tunneling field effect transistor

“…[1][2][3] PMA has been applied not only in the enhancement of transistors, but also for other devices that can benefit from an improvement in interface characteristics; in fact, PMA improves the mobility of surface-bound electrons, which immediately leads to an improvement in the performance of semiconductor devices. [4][5][6][7] In these regards, research has been actively conducted to investigate the application of PMA to metal-oxide-semiconductor field-effect transistors (MOSFETs). Efforts have been made to optimize the conditions of PMA on MOSFETs fabricated with a variety of materials, including silicon.…”