Dielectric Breakdown in Chemical Vapor Deposited Hexagonal Boron Nitride

Abstract

Insulating films are essential in multiple electronic devices because they can provide essential functionalities, such as capacitance effects and electrical fields. Two-dimensional (2D) layered materials have superb electronic, physical, chemical, thermal, and optical properties, and they can be effectively used to provide additional performances, such as flexibility and transparency. 2D layered insulators are called to be essential in future electronic devices, but their reliability, degradation kinetics, and dielectric breakdown (BD) process are still not understood. In this work, the dielectric breakdown process of multilayer hexagonal boron nitride (h-BN) is analyzed on the nanoscale and on the device level, and the experimental results are studied via theoretical models. It is found that under electrical stress, local charge accumulation and charge trapping/detrapping are the onset mechanisms for dielectric BD formation. By means of conductive atomic force microscopy, the BD event was triggered at several locations on the surface of different dielectrics (SiO, HfO, AlO, multilayer h-BN, and monolayer h-BN); BD-induced hillocks rapidly appeared on the surface of all of them when the BD was reached, except in monolayer h-BN. The high thermal conductivity of h-BN combined with the one-atom-thick nature are genuine factors contributing to heat dissipation at the BD spot, which avoids self-accelerated and thermally driven catastrophic BD. These results point to monolayer h-BN as a sublime dielectric in terms of reliability, which may have important implications in future digital electronic devices.

Recommended Methods to Study Resistive Switching Devices

“…The best quality material is normally achieved by mechanical exfoliation, but this leads to small material flakes (typically <10 µm) with uncontrollable thicknesses, [78] and it requires EBL to pattern the electrodes. [7] CVD can be used to grow high quality graphene, [80] molybdenum disulfide (MoS 2 ), [81] molybdenum diselenide (MoSe 2 ), [82] tungsten disulfide (WS 2 ), [83] tungsten selenide (WSe 2 ), [84] and hexagonal boron nitride (h-BN), [85][86][87] among many others. The two most widespread methods to synthesize 2D materials applied to RS devices are chemical vapor deposition (CVD) and liquid-phase exfoliation.…”

“…The two most widespread methods to synthesize 2D materials applied to RS devices are chemical vapor deposition (CVD) and liquid-phase exfoliation. [89][90][91] A solution commonly employed is to synthesize the 2D material on the most suitable substrates (metallic foils for graphene [80] and h-BN [85][86][87] and SiO 2 or sapphire for 2D transition metal dichalcogenides (TMDs) [81][82][83] ) and transfer it on the desired sample using different methods, [92][93][94] being the wet transfer with the assistance of a polymer scaffold the most used by the RS community. The problem is that the temperature used for the growth is typically >700 °C, which prevents growing the 2D material on wafers with existing integrated circuits due to diffusion problems; the maximum temperature allowed for complementary metal-oxidesemiconductor (CMOS) back-end of line integration is typically 450 °C.…”

A Review on Dielectric Breakdown in Thin Dielectrics: Silicon Dioxide, High‐k, and Layered Dielectrics

“…For modeling the d I BD /d t in h‐BN layers, the following parameters have been used; t ox = 3 nm, k = 300 W mK −1 , and E a = 1.1 eV. Reproduced with permission . Copyright 2017, American Chemical Society (ACS).…”

“…To clarify this issue additional experiments have been performed. The effect of the BD event has been analyzed via CAFM comparing multilayers with monolayers, both of h‐BN . Voltage sweeps from 0 V to V MAX have been applied at different locations on the bare surface of a 5–7 layer thick h‐BN/CuNi sample (locations A‐I in Figure a); the value of V MAX was 8 V at positions A–C, 4 V at positions D–F, and 2.5 V at positions G–I (respectively).…”

“…The inset in panel (c) is the current map of one hillock (blue = 0 pA, yellow = 10 pA). Reproduced with permission . Copyright 2017, ACS.…”