Newly Introduced Ultrathin Boron Nitride Films Further Efforts in Miniaturizing Electronic Devices

July 11, 2020 by Luke James

A new study led by researchers at the Ulsan National Institute of Science and Technology (UNIST) has unveiled ultrathin boron nitride films for next-generation electronics.

An international research team led by scientists at the Ulsan National Institute of Science and Technology, in partnership with researchers from the University of Cambridge and the Catalan Institute of Nanoscience and Nanotechnology, claims to have discovered a novel material that could enable further innovation in the field of electronic device miniaturization. 

This new material comes from the joint study where the research team successfully demonstrated the synthesis of thin films of amorphous boron nitride (a-BN) that featured extremely low dielectric constant, high breakdown voltage, and superior metal battier properties. 


Potential in Next-Gen Electronic Circuits

According to the research team, their newly fabricated material holds great potential for next-generation electronic circuits, such as interconnect insulators. This is promising because, in the ongoing miniaturization process of logic and memory devices in electronic circuits, the interconnects—the wires that connect different chip components—also need to be made smaller to guarantee improved performance. 

To date, extensive research efforts have been devoted to decreasing the resistance of scaled interconnects because the integration of dielectrics using CMOS-compatible processes has proven to be very challenging. According to the research team, the interconnect isolation materials needed should have low relative dielectric constants and be thermally, mechanically, and chemically stable. 

As such, lots of work has been poured into obtaining materials with low relative dielectric constants (k-values) and avoid artificially adding pores in thin films. And although several attempts have been made to develop materials with the desired characteristics, these have often failed to be successfully integrated into interconnects due to poor mechanical properties and chemical stability, which lead to failures. 


A remote ICP-CVD system for precise control of borazine flow.

An illustration of the remote ICP-CVD system with a borazine mass flow controller for precise control of borazine flow. The a-BN films were grown on Si substrates at 400°C. Image used courtesy of the University of Cambridge, Catalan Institute of Nanoscience and Nanotechnology


a-BN with "Extremely Low-k Dielectrics"

In their work, the joint research team has reportedly succeeded in demonstrating an approach to grow a-BN with extremely low-k dielectrics. In particular, the team synthesized around 3 nm thin a-BN on a silicon substrate. They achieved this using low temperature remote inductively coupled plasma chemical vapor deposition (ICP-CVD). The a-BN material showed an extremely low dielectric constant 30% lower than that of currently available insulators. 

"We found that temperature was the most important parameter with ideal a-BN film deposition occurring at 400° C," says Seokmo Hong in the Doctoral program of Natural Sciences, the first author. "This material with ultra-low-k also manifests a high breakdown voltage and likely superior metal barrier properties, making the film very attractive for practical electronic applications."

The material also exhibits excellent mechanical properties, and when researchers tested the diffusion barrier properties in harsh conditions, they say that it can prevent metal atom migration from the interconnects into the insulator.

According to the researchers, this will help resolve the long-standing challenge of interconnects in CMOS IC fabrication, enabling further device miniaturization when demand for smaller and more compact electronic solutions is growing. If the team's a-BN material is commercialized, it could be a great help in overcoming the looming crisis facing the semiconductor industry.