Insight into Selective Surface Reactions of Dimethylamino-trimethylsilane for Area-Selective Deposition of Metal, Nitride, and Oxide

Abstract

Area-selective deposition (ASD) is a promising bottom-up manufacturing solution for catalysts and nanoelectronic devices. However, industrial applications are limited as highly selective ASD processes exist only for few materials. “Passivation/deposition/defect removal” cycles have been proposed to increase selectivity, but cycling requires the passivation to be selective to the growth surface as well as the ASD-grown material. Dimethylamino-trimethylsilane (DMA-TMS) can passivate SiO2 surfaces by covering them with −Si­(CH3)3 groups. However, the interaction of DMA-TMS with materials other than SiO2 and Si remains largely unknown and its compatibility with cycling is not yet understood. This work investigates the selectivity of metal, nitride, and oxide atomic layer deposition (ALD) to DMA-TMS-passivated SiO2 as well as the surface chemistry and selectivity of the DMA-TMS reaction. The ALD coreagents O2, NH3, and H2O show low reactivity with the −Si­(CH3)3-terminated surface at temperatures up to 300 °C, but the selectivity of ALD strongly depends on the metal precursor and temperature. We demonstrate that DMA-TMS is a selective passivation agent for ASD of and on TiO2, TiN, and Ru selective to SiO2, by TiCl4/H2O, TiCl4/NH3, and EBECHRu/O2 ALD, respectively. We investigate the DMA-TMS reaction on Ru and TiN/TiO2 growth surfaces under conditions that passivate SiO2. At least 77% of the area of the growth surface remains reactive for ALD, confirming the compatibility of DMA-TMS with cycling for ASD. We investigate the impact of changes in surface composition due to patterning before ASD and find that DMA-TMS removes F impurities on TiN and TiO2 surfaces. DMA-TMS selectively passivates SiO2 on three-dimensional (3D) nanopatterns, allowing preferential TiO2 deposition on a nonpassivated growth surface. Thus, the selectivity of DMA-TMS shows great promise to expand the ASD material space as well as to increase selectivity during ASD cycles.

Area-Selective Deposition of Ruthenium by Area-Dependent Surface Diffusion

“…The 70 nm deep trenches are etched in SiO2, exposing the TiN growth surface at the bottom of each trench. Some SiO2 substrates were treated with DMA-TMS at 250 ˚C for 300 s to produce a Si-CH3 terminated SiO2 surface 18 . Some of the TiN/SiO2 nanopatterns were subject to a DMA-TMS treatment to obtain a well-defined -CH3 terminated SiO2.…”

“…To date, ASD can be achieved through different approaches, many of which rely on the combined use of surface modifications and vapor phase deposition techniques such as chemical vapor deposition (CVD) [10][11][12][13] and atomic layer deposition (ALD) 4, [14][15] . Surface modifications are typically aimed at suppressing the adsorption of precursor molecules on nongrowth surfaces [16][17][18][19][20][21][22][23][24][25][26][27] . However, the growth and morphology of deposits is not dictated by adsorption alone, but is rather the result of the competition between adsorption, surface diffusion, and aggregation of adspecies [28][29][30][31] (Figure 1).…”

Selectivity Enhancement for Ruthenium Atomic Layer Deposition in Sub‐50 nm Nanopatterns by Diffusion and Size‐Dependent Reactivity

“…[13] However, the pristine OSG surface is not representative for ASD as the surface composition changes from methyl-terminated OSG to hydroxyl-terminated SiO 2 during the patterning processes, and restoration of the methyl-termination is required to enable Ru ASD by ALD, for example by N,N-dimethylamino-trimethylsilane (DMA-TMS). [32,38,39] We therefore first investigate the Ru ALD growth mechanism on blanket SiO 2 substrates passivated with DMA-TMS (SiO 2 -OSi(CH 3 ) 3 ). SiO 2 is an omnipresent material in nanoelectronics and is a typical nongrowth surface for many practical implementations of Ru ASD.…”

“…This could be related to the lack of studies in patterns with nanoscale dimensions: high impact on selectivity is expected especially in patterns with dimensions in the same order of magnitude as the diffusion length, which is only 16 nm for Ru adspecies in the EBECHRu/O 2 Ru ALD process on OSG. [13,19,32] Another interesting feature of this Ru ALD process is the size-dependent reactivity of Ru nanoparticles. Ru nanoparticles that are too small to catalyze O 2 dissociation do not grow by precursor adsorption, which intrinsically limits the nanoparticle growth.…”

Origin of area selective plasma enhanced chemical vapor deposition of microcrystalline silicon

“…For AS-ALD, the passivation of the non-growth surface results from a pretreatment prior to the film deposition process. This can be done either by using organic films such as self-assembled monolayers (SAMs) [13][14][15][16] or polymers 17 that preferentially react with a certain type of surfaces (metal or oxides) inhibiting any film growth, or by exposing the surface to an H2 plasma 18 . However, many constraints face this methodology, such as the adsorption of the precursor on the inhibitor, or losing the inhibitor molecules after few cycles 19 .…”