A research team at Hanyang University developed a selector device using pure silicon dioxide (SiO₂) and elucidated its operating principle. It is evaluated as a technology that simultaneously secures the stability and process compatibility required for next-generation high-density memory structures.

A research team led by Professor Tae-Joo Park at Hanyang University announced on the 14th that they have implemented a pure SiO₂-based selector and elucidated the operating principle of the device.

The research results explained that the structure is compatible with CMOS (Complementary Metal-Oxide Semiconductor) processes and suggests potential applications in next-generation memory and computing technologies.

■ Implementation of SiO₂-based selection device

Recently, 3D structured memory technology is being utilized in the semiconductor industry to cope with the increase in data throughput.

Among these, the crossbar array is considered a structure capable of achieving high integration density, but it has been pointed out that there are limitations to stable operation due to the 'sneak path' problem, where current flows to unselected cells.

To solve this, the research team focused on a selector that controls the current flow.

Unlike existing chalcogenide-based or metal ion composite oxide materials, SiO₂, an insulator widely used in semiconductor processes, was utilized.

A thin film of SiO₂ with a thickness of about 5 nm was formed between the upper and lower TiN electrodes using atomic layer deposition (ALD), and it was confirmed that a 'threshold switching' characteristic in which current flows only above a specific voltage was observed.

The device showed a switching speed of approximately 400ns and a durability of more than 10 cycles, and it was found that it could be fabricated in a process below 300℃ and maintained stability even after heat treatment.


■ Elucidation of Oxygen-Based Operation Mechanism

The research team also conducted an analysis of the operating mechanism along with the device implementation.

Through the analysis of the interface structure and electrical properties, it was confirmed that oxygen vacancies within SiO₂ act as a major factor in the formation of threshold switching characteristics.

In particular, they stated that a phenomenon was observed in which the current increased rapidly as the distribution of oxygen vacancies and the charge state changed during the electrical generation process. The research team explained that these results suggest that the operating voltage of the device can be controlled by adjusting the state of oxygen vacancies.

This research was conducted through industry-academia collaboration with SK Hynix and supported by the National Research Foundation of Korea and the Korea Basic Science Institute.

The research results were published in the international academic journal 'ACS Applied Materials & Interfaces' on April 1 and selected as a cover article.