Atmospheric-Pressure Plasma-Enhanced Spatial ALD of SiO₂ Studied by Gas-Phase Infrared and Optical Emission Spectroscopy

Abstract

An atmospheric-pressure plasma-enhanced spatial atomic layer deposition (PE-s-ALD) process for SiO2 using bisdiethylaminosilane (BDEAS, SiH2[NEt2]2) and O2 plasma is reported along with an investigation of its underlying growth mechanism. Within the temperature range of 100–250 °C, the process demonstrates self-limiting growth with a growth per cycle (GPC) between 0.12 and 0.14 nm and SiO2 films exhibiting material properties on par with those reported for low-pressure PEALD. Gas-phase infrared spectroscopy on the reactant exhaust gases and optical emission spectroscopy (OES) on the plasma region are used to identify the species that are involved in the ALD process. Based on the identified species, we propose a reaction mechanism where BDEAS molecules adsorb on −OH surface sites through the exchange of one of the amine ligands upon desorption of diethylamine (DEA). The remaining amine ligand is removed through combustion reactions activated by the O2 plasma species leading to the release of H2O, CO2, and CO in addition to products such as N2O, NO2, and CH-containing species. These volatile species can undergo further gas-phase reactions in the plasma as indicated by the observation of OH*, CN*, and NH* excited fragments in OES. Furthermore, the infrared analysis of the precursor exhaust gas indicated the release of CO2 during precursor adsorption. Moreover, this analysis has allowed the quantification of the precursor depletion yielding values between 10 and 50% depending on the processing parameters. Besides providing insights into the chemistry of atmospheric-pressure PE-s-ALD of SiO2, our results demonstrate that infrared spectroscopy performed on exhaust gases is a valuable approach to quantify relevant process parameters, which can ultimately help evaluate and improve process performance.

Atmospheric-pressure plasma-enhanced spatial atomic layer deposition of silicon nitride at low temperature

“…material 1: fig. S1, which is in good agreement with an earlier report on SiO 2 spatial ALD using the same precursor [4].…”

“…In conventional, temporal ALD, a substrate is cyclically exposed to a precursor and a coreactant that are separated in time and undergo self-limiting surface reactions, thus allowing for Ångströmlevel thickness control and unparalleled uniformity and conformality over 3D substrates. In the case of PE-ALD, the plasma-activated co-reactant can effectively reduce the thermal budget required for film deposition, and often allows for improved layer properties, compared to those of layers grown with thermal ALD [4,5].…”

“…Therefore much shorter ALD cycle times can be achieved [14]. Most of the literature on spatial ALD concerns metal oxides produced either by thermal or plasma-enhanced spatial ALD, [4,[15][16][17] and only a few examples have been published for spatial-ALD of metallic films (Ag and Cu) [18,19]. To our knowledge, no attempts have been reported so far to deposit nitrides in an atmospheric-pressure spatial ALD set-up.…”

Area‐selective atomic layer deposition on HOPG enabled by writable electron beam functionalization

“…[ 1 ] With the continued downscaling of devices and a shift away from traditional planar device architecture, these top‐down approaches face challenges with resolution and alignment. [ 1 , 2 ] To continue advancing Moore's law, bottom‐up nanofabrication techniques with improved spatial control [ 3 ] over the placement, selectivity, and dimension of thin films are being developed. Atomic layer deposition (ALD) is a robust tool for bottom‐up deposition of thin films of oxides, metals, sulfides, fluorides, and other materials at relatively low temperatures [ 4 ] and is attractive for next‐generation semiconductor manufacturing processes.…”

“…The technique builds on recent work in which localized defect engineering of graphene was demonstrated by introducing OH species to the graphene surface. [40] By exploiting the electron beam-induced chemistry, sp 3 -type defects were introduced to graphene without etching the carbon in the lattice. [39] The resulting defects included -COOH (carboxyl) and C-OH (hydroxyl) bonds, as characterized by X-ray photoelectron spectroscopy.…”