Inherently Area‐Selective Atomic Layer Deposition of SiO₂ Thin Films to Confer Oxide Versus Nitride Selectivity

Abstract

Area‐selective atomic layer deposition (AS‐ALD) offers tremendous advantages in comparison with conventional top‐down patterning processes that atomic‐level selective deposition can achieve in a bottom‐up fashion on pre‐defined areas in multi‐dimensional structures. In this work, a method for exploiting substrate‐dependent selectivity of aminosilane precursors for oxides versus nitrides through chemo‐selective adsorption is reported. For this purpose, AS‐ALD of SiO2 thin films on SiO2 substrates rather than on SiN substrates are investigated. Theoretical screening using density functional theory (DFT) calculations are performed to identify Si precursors that maximize adsorption selectivity; results indicate that di(isopropylamino)silane (DIPAS) has the potential to function as a highly chemo‐selective precursor. Application of this precursor to SiN and SiO2 substrates result in inherent deposition selectivity of ≈4 nm without the aid of surface inhibitors. Furthermore, deposition selectivity is enhanced using an ALD‐etch supercycle in which an etching step inserts periodically after a certain number of ALD SiO2 cycles. Thereby, enlarged deposition selectivity greater than ≈10 nm is successfully achieved on both blanket‐ and SiO2/SiN‐patterned substrates. Finally, area‐selective SiO2 thin films over 4–5 nm are demonstrated inside 3D nanostructure. This approach for performing inherent AS‐ALD expands the potential utility of bottom‐up nanofabrication techniques for next‐generation nanoelectronic applications.

Nanometric 3D Printing of Functional Materials by Atomic Layer Deposition

“…It was then proposed to regularly add the surface treatment step (passivation step) in the ALD cycles changing a cycle from a (treatment + AB) process to an (ABC) cycle with the treatment reinjected regularly [23]. Another proposed solution is to use super-cycles with the injection of etching steps every x ALD cycles, this is called ASD by super-cycles of deposition-etching [24][25][26][27][28]. In the end, with these different ASD strategies, passivation or super-cycles, [29] the possibility to deposit thin films of more than 10 nm on a previously selected surface has been successfully demonstrated.…”

Area‐Selective Atomic Layer Deposition Using Vapor Dosing of Short‐Chain Alkanethiol Inhibitors on Metal/Dielectric Surfaces

“…Recently, as state-of-the-art technology enters the sub-10-nm scale, the conventional top-down patterning of thin films is undergoing significant challenges with regard to atomic-scale precision and reliable processing. [1][2][3] In particular, issues with misalignment of multilevel pattern structures, so-called edgeplacement errors, arising from the large number of lithographic steps are considered a prime bottleneck limiting the advancement to smaller technology nodes in the semiconductor industry. [3][4][5][6] In this context, area-selective atomic layer deposition (AS-ALD) is gaining considerable attention as a means of significantly improving current top-down fabrication approaches by introducing a bottom-up additive process chains.…”

“…[1][2][3] In particular, issues with misalignment of multilevel pattern structures, so-called edgeplacement errors, arising from the large number of lithographic steps are considered a prime bottleneck limiting the advancement to smaller technology nodes in the semiconductor industry. [3][4][5][6] In this context, area-selective atomic layer deposition (AS-ALD) is gaining considerable attention as a means of significantly improving current top-down fabrication approaches by introducing a bottom-up additive process chains. [7,17] Indeed, though the van der Waals interaction was not taken into account, stochastic packing simulations with regard to one of the short-chain aminosilanes, bis(N,N-dimethylamino) dimethylsilane, corroborated the restricted accommodation of ≈50% on the hydroxyl surface at its saturation on account of the steric interactions between the adsorbates, indicating that the subsequent ALD process is difficult to inhibit.…”

“…[7] In this regard, one of the biggest challenges with respect to the industrial application of AS-ALD with such small inhibitor molecules involves securing high enough deposition selectivity. [3,5] We recently demonstrated a methodology for enhanced deposition selectivity with a discrete feeding method of aminosilane inhibitors, in which dividing inhibitor feeding periods into cut-in purge steps enabled improved chemisorption density of small alkylating agents, avoiding undesired pseudo-saturation via the molecular screening effect from transient physisorption during the initial precursor feeding step. [5] More interestingly, it is worth noting that further extension of deposition selectivity can be enabled through either a post-correcting etch step [23,27] or redosing SAMs.…”

“…

with modification of surface characteristics, which allows a desired film to be deposited on one region of pre-patterned surfaces (i.e., growth areas) while simultaneously inhibiting deposition in adjacent regions (i.e., non-growth areas). [3,[7][8][9][10] One of the most common strategies for the successful implementation of AS-ALD is to locally deactivate non-growth areas with self-assembled monolayers (SAMs) as inhibitor molecules. [11][12][13][14][15][16][17] In other words, surface modification with such alkylating agents is the most important prerequisite in that the subsequent ALD process operates with a strong dependence of the surface character in the employed substrates by virtue of a surface-reaction-controlled regime with an alternating exposure of precursor and co-reactant molecules.

…”