Ultralow-dielectric-constant amorphous boron nitride

Abstract

The decrease in signal processing speed due to increased resistance and capacitance delay resulting from aggressive miniaturisation of logic and memory devices is a major obstacle for continued down scaling of electronics. 1-3 In particular, minimizing the dimensions of interconnects -metal wires that connect different device components on the chip -is crucial for device scaling. The interconnects are isolated from each other by nonconducting or dielectric layers. Much of the recent research has focused on decreasing the resistance of scaled interconnects because integration of dielectrics using complementary metal oxide semiconductor (CMOS) compatible processes has proven to be exceptionally challenging. The key requirements for interconnect isolation materials are that they should possess low relative dielectric constants (referred to as values), serve as diffusion barriers against migration of interconnect metals such as cobalt into semiconductors and be thermally, chemically and mechanically stable. In 2005, the International Roadmap for Devices and Systems (IRDS) recommended dielectrics with -values of < 2.2 and the most recent report recommends dielectric values of ≤ 2 by 2028. 4 Despite this, state-of-the-art low- materials, such as silicon oxide derivatives, organic compounds, and aerogels exhibit  values > 2 and possess poor thermomechanical properties. 5 Here, we report a dielectric thin film with ultra-low  values of1.78 and 1.16 -close to that of air ( = 1) -at 100 kHz and 1 MHz, respectively, in amorphous boron nitride (a-BN) obtained using CMOS compatible low temperature process. We demonstrate that 3 nm thin a-BN is mechanically and electrically robust with breakdown strength of 7.3 MV/cm -exceeding requirements. Cross-sectional transmission electron microscopy reveals that a-BN is able to prevent diffusion of cobalt interconnect atoms into silicon under very harsh accelerated conditions -in contrast with

The Properties and Preparation Methods of Different Boron Nitride Nanostructures and Applications of Related Nanocomposites

“…The resistivity of BN at room temperature is 10 16 ∼10 18 Ω ⋅ cm, and it can be stabilized at about 10 4 Ω ⋅ cm at 2000 °C, indicating its excellent high‐temperature insulation [82] . In addition, the large band gap (bulk BN is about 5.2–5.4 eV, h‐BN and c‐BN are found to be as high as 6 and 6.5 eV, respectively), surface optical phonon modes (with energies two times higher than SiO 2 ), [90] dielectric characteristics (ϵ=3–4), [91] and high in‐plane breakdown electric field (35 kV/mm) make BN as an excellent dielectric substrate in the insulation shielding performance better than graphene, molybdenum disulfide, and other low‐dimensional nanomaterials [92] …”

Building Functional Memories and Logic Circuits with 2D Boron Nitride

“…fabricated amorphous a‐BN with low relative dielectric constants, which can be used as diffusion barriers, instead of tunneling barriers for h‐BN, to protect channels from the migration of metal atoms in the electrodes. [ 200 ] The a‐BN films have relative dielectric constants as low as 1.16 at a working frequency of 1 MHz, which is beneficial to be the interconnect isolating materials in the applications of large‐scale complementary metal–oxide semiconductor (CMOS) electronics.…”

Analytical Study of Porous Organosilicate Glass Films Prepared from Mixtures of 1,3,5- and 1,3-Alkoxysilylbenzenes

“…Many different materials have been evaluated during the last 20 years as potential lowk candidates [4,5]. Currently, organosilicate glasses (OSG) have been selected as the most suitable for modern BEOL integration technology, although other candidates, such as metal organic frameworks, amorphous boron nitride and some others are still under study [4,6,7]. OSG low-k materials are also termed carbon-doped oxides (SiCOH) and have a structure similar to traditional silicon dioxide, where a part of oxygen-bridging atoms is replaced with terminal methyl groups.…”