Ultralow‐k Amorphous Boron Nitride Based on Hexagonal Ring Stacking Framework for 300 mm Silicon Technology Platform

Abstract

The implementation of ultralow dielectric constant (k value ≈ 2) materials to reduce signal propagation delay in advanced electronic devices represents a critical challenge in next generations of microelectronics technologies. The introduction of well‐stacked and low polarity molecules that do not compromise film density may lead to improvements and desirable material engineering, as conventional porous SiOx derivatives exhibit detrimental degradation of thermo‐mechanical properties when their k values are further scaled down. This work presents a systematic engineering approach for controlling ultralow‐k amorphous boron nitride (aBN) deposition on 300 mm Si platforms. The results indicate that aBN grown from borazine precursor exhibits ultralow dielectric constant ≈2, high density, excellent mechanical strength, and extended thermodynamic stability. Unintentional boron ion doping during plasma dissociation that may induce artificial reductions of k value on n‐type substrates is alleviated by employing a remote microwave plasma process. Moreover, the adoption of low growth rate processes for ultralow‐k aBN deposition is found to be critical to provide for the superior mechanical strength and high density, and is attributed to the formation of hexagonal ring stacking frameworks. These results pave the way and offer engineering solutions for new ultralow‐k material introduction into future semiconductor manufacturing applications.

Revealing the improved stability of amorphous boron-nitride upon carbon doping

“…However, larger H doping worsens the mechanical properties due to fewer sp 3 -hybridized atoms, lower density, and more porous structure. Reduction in mechanical properties with lower density and sp 3 -hybridized atoms has already been shown for α-BN and other amorphous structures [10,9,34,35,36]. Even though the reported Young's modulus values in this study are lower than hexagonal and cubic BN, α-BN:H still has superior mechanical properties than other ultralow-dielectric materials.…”

“…8,9 Atomically thin α-BN has been recently demonstrated to possess ultralow dielectric constant ( k < 2), low metal diffusivity and high mechanical robustness. 10,11 This recent breakthrough follows years of efforts in the pursuit of wafer-scale fabrication of atomically thin h-BN on various types of substrates, for potential use in the integration with graphene and/or transition metal dichalcogenides for nanoelectronic devices and circuits. 12–16…”

“…A potential new barrier dielectric has recently emerged, amorphous boron nitride (α-BN). Experimental reports on α-BN indicate that it has a low dielectric constant, kvalues lower than 2, and exhibits higher stability and mechanical properties compared to other low dielectric materials such as organic polymeric materials [7,8,9]. In addition, theoretical predictions suggest that a certain density of carbon content improves the structural and thermal properties of α-BN:C [10].…”

Impact of hydrogenation on the stability and mechanical properties of amorphous boron nitride

“…However, larger H doping worsens the mechanical properties due to fewer sp 3 -hybridized atoms, lower density, and more porous structure. Reduction in mechanical properties with lower density and sp 3 -hybridized atoms has already been shown for α-BN and other amorphous structures [9,10,[34][35][36]. Even though the reported Young's modulus values in this study are lower than hexagonal and cubic BN, α-BN:H still has superior mechanical properties than other ultralow-dielectric materials.…”

“…A potential new barrier dielectric has recently emerged, amorphous boron nitride (aBN) (α-BN). Experimental reports on α-BN indicate that it has a low dielectric constant, k-values lower than 2, and exhibits higher stability and mechanical properties compared to other low dielectric materials such as organic polymeric materials [7][8][9]. In addition, theoretical predictions suggest that a certain density of carbon content improves the structural and thermal properties of α-BN:C [10].…”