Area-selective deposition (ASD) provides promise to facilitate the fabrication of nano-electronic devices with 2D transition metal dichalcogenide channels. This paper explores Ru ASD by chemical vapor deposition (CVD) on a Si/SiO2 substrate that is partly covered by triangular single-layer WS2 crystals. Opposite to most chemically driven deposition techniques, this Ru deposition is inherently selective, with the WS2 basal plane being more active than the WS2 crystals edges. Continuous Ru layers form on the basal plane of the WS2 crystals with less than 2% selectivity loss on the SiO2 surface. Ru deposition initiates near the WS2 crystal edges and expands over the WS2 basal plane with a lateral growth rate that is more than 10 times larger than the vertical growth rate. The anisotropic growth is attributed to diffusion-mediated aggregation of Ru adspecies on the WS2 basal plane. Moreover, experimental observations are consistent with theoretical predictions for self-confined deposition on the WS2 crystals, while there is no physical barrier to prevent lateral overgrowth. The obtained insights are relevant for a wide range of applications that rely on chemically driven deposition on 2D materials, and promote further research on precise nanopattern replication by self-confined growth without relying on physical barriers.

Area-selective deposition (ASD) is a bottom-up patterning technique that is of interest for nanoprocessing and next-generation semiconductor device manufacturing. This work demonstrates the great potential of dechlorosilylation chemistry for ASD through the example of Ge2Sb2Te5 (GST), a promising phase change material for storage class memory (SCM) applications. The fabrication of SCM devices may be facilitated by ASD as it involves complex nanoscale three-dimensional structures. We therefore investigate GST ASD on a TiN growth area with SiO2 as a nongrowth area. A selectivity of >0.9 is maintained up to similar to 45 nm of GST by using a single reaction of an aminosilane small molecule inhibitor in combination with GST atomic layer deposition (ALD) with GeCl2C4H8O2, SbCl3, and Te[(CH3)(3)Si](2) as precursors at 70 degrees C. The high selectivity is maintained for much thicker films compared to that of previously investigated ALD chemistries that use other precursors and O-2, H2O, or NH3 co-reagents in combination with the same inhibitor. Interestingly, the selectivity, the ideal 2:2:5 composition, and the amorphous phase of Ge2Sb2Te5 are maintained during ASD on SiO2/TiN line patterns with a half-pitch of 45 nm. A careful study of the growth evolution suggests that the growth mechanism for ASD on these nanopatterns relies on diffusion in addition to adsorption, indicating that diffusion-mediated selective deposition is not limited to metal ASD processes such as those of Ru and Pt. We propose that the combination of the ALD dechlorosilylation chemistry with passivation approaches including small molecule inhibitors creates a promising avenue for expanding the ASD material space to a wide range of new materials, enabling new applications for ASD in nanoelectronics, nanoprocessing, catalysis, etc.

Area-selective deposition (ASD) is a bottom-up technique that provides numerous opportunities for nanoelectronic device fabrication. For example, advanced nano-interconnect structures with barrierless metals like Ru in the contact holes can be created by Ru ASD with the bottom metals as growth surfaces and dielectrics as non-growth surfaces. This work investigates Ru ASD by chemical vapor deposition (CVD) on industrially relevant substrates and nanopatterns and reveals how selectivity and growth rate are modulated by the CVD conditions and type of nanopattern. For low-k dielectric/Cu substrate combinations, the selectivity reverses from metal-on-metal to metal-on-dielectric upon only changing the CVD co-reagent from H2 to NH3. In contrast, NH3 is the preferred co-reagent for SiO2-TiN line patterns with critical dimension (CD) of 40 nm due to the more favorable adsorption and diffusion kinetics that cause growth rate and selectivity enhancement. Consistent with a diffusion-mediated mechanism, the growth rate enhances even more for Ru CVD on nanoscale contact holes with CD of 10.5 nm, becoming 2.4 times higher as compared to unpatterned substrates. Thus, the ASD process changes drastically when pattern dimensions reach the nanoscale. The reported insights facilitate rational design of metal ASD processes for multiple applications in nanofabrication. This work reveals how the selectivity and growth rate of ruthenium area-selective deposition are modulated by the deposition conditions, substrate materials, and type of nanopatterns. The growth rate increases on nanoscale patterns, consistent with a diffusion-mediated growth mechanism. This enables to maintain selectivity up to higher thickness, which holds promise for advanced semiconductor device fabrication and other nanoscale applications.image

Small-molecule inhibitors have recently been introduced for passivation during area-selective deposition (ASD). Small silanes like (N,N-dimethylamino)trimethylsilane (DMATMS) selectively react with −OH sites on SiO2 to form a less reactive –OSi(CH3)3 terminated surface. The –OSi(CH3)3 surface termination can inhibit many atomic layer deposition (ALD) processes, including TiCl4/H2O ALD. However, the mechanisms by which ALD is inhibited and by which selectivity is eventually lost are not well understood. This study uses in situ Fourier-transform infrared spectroscopy to probe the adsorption of DMATMS on SiO2 and the subsequent reactions when the passivated surface is exposed to TiCl4/H2O ALD. The chemisorption of DMATMS on isolated –OH groups on SiO2 is shown to inhibit the reaction with TiCl4. Further, we find that starting with an inherently inhibiting H-terminated Si surface, DMATMS can also react with residual –OH groups and reduce the extent of nucleation. Finally, using Rutherford backscattering spectrometry, the effectiveness of DMATMS passivation on SiO2 and H-terminated Si is quantified during extended ALD cycle numbers. The insight into the mechanisms of passivation by DMATMS and passivation loss can enable the rational design of highly selective ASD processes by carefully matching compatible surfaces, passivating agents, and ALD precursors.

Area-selective deposition (ASD) is a possible enabler for the fabrication of various future semiconductor devices. However, it remains challenging to characterize and optimize ASD processes in patterns with nanoscale dimensions, as required for semiconductor device applications. Therefore, we study Ru ASD on different types of nanopatterns on 300 mm-wafers and assess the role of the pattern geometry and density on selectivity. As selectivity is often improved by means of passivation-deposition-etch cycles, we investigate an ASD cycle consisting of passivation by (N,N-dimethylamino)trimethylsilane, deposition by (ethylbenzyl)(1-ethyl-1,4-cyclohexadienyl)Ru/O2 atomic layer deposition (ALD) and an O/Cl plasma etch. On line-space patterns with a 32 nm critical dimension, the passivation-deposition-etch cycle yields a lower defectivity level than the passivation-deposition approach for a given Ru ASD thickness. The comparison of Ru ASD on line-space and hole nanopatterns reveals the pattern-dependent selectivity, that is explained by accumulation of Ru nanoparticles at pattern edges. 300 mm-wafer uniformity is also investigated and related to reactor design. The investigation of ASD on nanopatterned 300 mm-wafers is enabled by ASD-specific developments of X-ray photoelectron spectroscopy, optical critical dimension scatterometry, and scanning electron microscopy. This research highlights the possibilities and challenges in developing ASD processes in an industrial setting.

Area-selective atomic layer deposition (AS-ALD) is a coveted method for the fabrication of next-generation nano-electronic devices, as it can complement lithography and improve alignment through atomic scale control. Selective reactions of small molecule inhibitors (SMIs) can be used to deactivate growth on specific surface areas and as such enable AS-ALD. To investigate new applications of ASD, we need insight into the reactions of SMIs with a broad range of technology relevant materials. This paper investigates the reactions of aminosilane SMIs with a broad range of oxide surfaces and the impact on subsequent atomic layer deposition (ALD). We compare the reactions of two aminosilane SMIs, namely, dimethylamino-trimethylsilane (DMA-TMS) and hexamethyldisilazane (HMDS), with a hydroxylated SiO2 surface and the impact on subsequent ALD processes. The DMA-TMS reaction saturates faster than the HMDS reaction and forms a dense trimethylsilyl (TMS) layer with a higher TMS surface concentration. The higher TMS surface concentration yields better inhibition and higher selectivity during subsequent TiO2 ALD. We show that a wide range of surfaces, i.e., MgO, HfO2, ZrO2, Al2O3, TiO2 (TiN/TiOx), SiO2, SnO2, MoOx, and WO3 remain reactive after DMA-TMS exposure for conditions where SiO2 is passivated, indicating that DMA-TMS can enable AS-ALD on these surfaces with respect to SiO2. On these surfaces, DMA-TMS forms residual TMS and/or SiOxCyHz surface species that do not markedly inhibit ALD but may affect interface purity. Surfaces with lower, similar, and higher surface acidity than SiO2 all show less reactivity toward DMA-TMS, suggesting that surface acidity is not the only factor affecting the substrate-inhibitor interaction. Our study also compares a hybrid inorganic-organic SnOxCyHz and inorganic SnO2 material in view of their relevance as resist for extreme ultraviolet lithography. DMA-TMS can enable selective infiltration in SnOxCyHz, as opposed to selective deposition on SnO2, indicating tunable reactivity by bulk and surface composition. These insights into the reactivity of aminosilane SMIs may aid the design of new area-selective deposition processes, broaden the material space, and enable new applications.

Area‐selective deposition (ASD) is a promising bottom‐up approach for fabricating nanoelectronic devices. However, a challenge is to prevent the undesired growth of nanoparticles in the nongrowth area. This work uses kinetic Monte Carlo (KMC) methods to investigate the defectivity in ruthenium ASD by (ethylbenzyl)(1‐ethyl‐1,4‐cyclohexadienyl)Ru/O2 (EBECHRu) atomic layer deposition (ALD) in line‐space nanopatterns with different dimensions. Ru ASD is governed by adsorption as well as diffusion. The defectivity depends on the pattern dimensions, as nanoparticles can diffuse and reach the interface with the growth area where they aggregate. For linewidths of 50 nm and smaller, all Ru adspecies are captured at the growth interface before growth by precursor adsorption is catalyzed. The synergetic effect of diffusion and size‐dependent reactivity reduces defectivity below 1010 Ru atoms cm−2 for at least 1000 ALD cycles. This is more than 1000 times lower than for patterns with a linewidth of 200 nm and larger, where the Ru content decreases significantly only near the interface with the growth surface. The predicted depletion zone is confirmed by experiments in nanoscale line‐space patterns. Overall, this mechanism results in smaller and fewer Ru nanoparticles for smaller patterns, facilitating the development of passivation‐deposition‐etch ASD processes for nanoelectronic device fabrication.

Area-selective deposition (ASD) enables the growth of materials on target regions of patterned substrates for applications in fields ranging from microelectronics to catalysis. Selectivity is often achieved through surface modifications aimed at suppressing or promoting the adsorption of precursor molecules. Here we show, instead, that varying the surface composition can enable ASD by affecting surface diffusion rather than adsorption. Ru deposition from (carbonyl)- (alkylcyclohexadienyl)Ru and H2 produces smooth films on metal nitrides and nanoparticles on SiO2. The latter form by surface diffusion and aggregation of Ru adspecies. Kinetic modeling shows that changing the surface termination of SiO2 from -OH to -CH3, and thus its surface energy, leads to larger and fewer nanoparticles because of a 1000-fold increase in surface diffusion rates. Kinetic Monte Carlo simulations show that even surface diffusion alone can enable ASD because adspecies tend to migrate from high- to low-diffusivity regions. This is corroborated by deposition experiments on 3D TiN-SiO2 nanopatterns, which are consistent with Ru migrating from SiO2 to TiN. Such insights not only have implications for the interpretation of experimental results but may also inform new ASD protocols, based on chemical vapor and atomic layer deposition, that take advantage of surface diffusion.

The structure and as such the properties of alkanethiolate self-assembled monolayers (SAMs) on metal surfaces depend on the surface structure, thiolate coverage, and chain length. The chain length ...

Area‐selective deposition (ASD) receives increasing attention as a bottom‐up approach for nanoelectronic device fabrication. Uptake of ASD is however limited by defects, which manifest as undesired particle growth on the nongrowth surface. A defect mitigation solution is demonstrated for Ru ASD on TiN/SiO 2 nanopatterns by making use of the size‐dependent Ru nanoparticle reactivity. During the initial stages of 1‐(ethylbenzyl)‐1,4‐(ethylcyclohexadienyl)ruthenium and oxygen (EBECHRu/O 2 ) atomic layer deposition (ALD) on dielectrics, Ru particles are too small to catalytically dissociate oxygen, and their growth is suppressed. This phenomenon creates an ASD process window in which particles can be completely etched while retaining the integrity of the ASD pattern on a TiN growth surface. Decreasing the ALD temperature strongly suppresses defect growth, which can be used to expand the process window for ASD. The ASD process window is confirmed by self‐focusing secondary ion mass spectrometry (SF‐SIMS) with its low limit of detection while analyzing 10 4 structures simultaneously. No defects are detected for Ru ASD on 36 nm TiN/SiO 2 patterns by SF‐SIMS. The Ru ASD process is applied for bottom‐up block patterning and functional hardmask patterns are obtained on 300 mm wafers. The approach followed in this work can produce defect‐free ASD processes for a wide variety of applications.

Understanding the growth mechanisms during the early stages of atomic layer deposition (ALD) is of interest for several applications including thin film deposition, catalysis, and area-selective deposition. The surface dependence and growth mechanism of (ethylbenzyl)(1-ethyl-1,4-cyclohexadienyl)ruthenium and O-2 ALD at 325 degrees C on HfO2, Al2O3, -OH, and Si-O-Si terminated SiO2, and organosilicate glass (OSG) are investigated. The experimental results show that precursor adsorption is strongly affected by the surface termination of the dielectric, and proceeds most rapidly on -OH terminated dielectrics, followed by Si-O-Si and finally Si-CH3 terminated dielectrics. The initial stages of growth are characterized by the formation and growth of Ru nanoparticles, which is mediated by the diffusion of Ru species. Mean-field and kinetic Monte Carlo modeling show that ALD on OSG is best described when accounting for (1) cyclic generation of new nanoparticles at the surface, (2) surface diffusion of both atomic species and nanoparticles, and (3) size-dependent nanoparticle reactivity. In particular, the models indicate that precursor adsorption initially occurs only on the dielectric substrate, and occurs on the Ru nanoparticles only when these reach a critical size of about 0.85 nm. This phenomenon is attributed to the catalytic decomposition of oxygen requiring a minimum Ru nanoparticle size.