Relation between Reactive Surface Sites and Precursor Choice for Area-Selective Atomic Layer Deposition Using Small Molecule Inhibitors

Abstract

Implementation of vapor/phase dosing of small molecule inhibitors (SMIs) in advanced atomic layer deposition (ALD) cycles is currently being considered for bottom-up fabrication by area-selective ALD. When SMIs are used, it can be challenging to completely block precursor adsorption due to the inhibitor size and the relatively short vapor/phase exposures. Two strategies for precursor blocking are explored: (i) physically covering precursor adsorption sites, i.e., steric shielding, and (ii) eliminating precursor adsorption sites from the surface, i.e., chemical passivation. In this work, it is determined whether steric shielding is enough for effective precursor blocking during area-selective ALD or whether chemical passivation is required as well. At the same time, we address why some ALD precursors are more difficult to block than others. To this end, the blocking of the Al precursor molecules trimethylaluminum (TMA), dimethylaluminum isopropoxide (DMAI), and tris(dimethylamino)aluminum (TDMAA) was studied by using acetylacetone (Hacac) as inhibitor. It was found that DMAI and TDMAA are more easily blocked than TMA because they adsorb on the same surface sites as Hacac, while TMA is also reactive with other surface sites. This work shows that chemical passivation plays a crucial role for precursor blocking in concert with steric shielding. Moreover, the reactivity of the precursor with the surface groups on the non-growth area dictates the effectiveness of blocking precursor adsorption.

Extending growth inhibition during area-selective atomic layer deposition of Al2O3 on aminosilane-functionalized SiO2

“…DMAI is a heteroleptic precursor and less reactive than trimethyl aluminum, which is the most commonly used precursor for Al 2 O 3 ALD. 13 Our previous study 14 and other studies 15,16 have reported improved growth inhibition using DMAI as the Al precursor during area-selective ALD of Al 2 O 3 based on small molecule inhibitors. In an ALD cycle, the chamber was first filled with B30 mtorr of DAMI vapor with varied trapping time, followed by a 20 s Ar purge step.…”

Computational Investigation of Precursor Blocking during Area-Selective Atomic Layer Deposition Using Aniline as a Small-Molecule Inhibitor

“…Most of the conventional fabrication processes are designed on the basis of the top-down approach, comprising numerous deposition, lithography, and etching steps. , At small feature sizes, traditional top-down approaches suffer from alignment issues between the patterning steps . Therefore, processes exploiting the properties of the underlying pattern instead of purely relying on metrology and patterning precision are needed. , During the past decade, area-selective deposition (ASD), a bottom-up alternative enabling self-aligned fabrication schemes, has gained considerable attention in academia and industry. − ASD refers to processes that deposit the target material on the areas where the growth is desired (i.e., growth areas), while deposition is avoided on the neighboring areas where the growth is not desired (non-growth areas). The selectivity of deposition on the growth areas can be achieved by exploiting differences in the chemical or physical properties, such as different material compositions, surface terminations, or lattice properties. ,,, …”

Inhibitor-Free Area-Selective Atomic Layer Deposition with Feature Size Down to Nearly 10 nm

“…As the advanced semiconductor technology rapidly moves toward the 3 nm technology node and beyond, complicated multilayer structures in integrated circuits highly call for precise alignment . As a consequence, the conventional top–down fabrication processes based on extreme ultraviolet lithography and etching techniques severely suffer from misalignment (edge placement error) and more intricate fabrication processes, which has become a critical bottleneck hindering the evolution of semiconductor technology. − In the face of rigorous challenges, area-selective atomic layer deposition (AS-ALD) has been proposed as an enabling technology for novel bottom-up and self-aligned fabrication. ,, AS-ALD is capable of selectively depositing ultrathin films on the growth area (GA) and not upon the non-GA (NGA), which possesses a high potential to reduce the lithography and etching steps in advanced semiconductor technology nodes. For example, the fully self-aligned via (FSAV) structure has been regarded as one of the important applications of AS-ALD. , The FSAV technique can enhance the reliability of integrated circuits by increasing the distance between the neighboring metal vias. − Conventionally, the FSAV topography was fabricated by lithography and recess etching processes, which results in damage to metal surfaces .…”

“…For instance, trimethylaluminum (TMA, which is a commonly used ALD precursor) has to be replaced by dimethylaluminum isopropoxide (DMAI) or tris(dimethylamino)aluminum (TDMAA) to prevent selectivity loss. 1 However, the DMAI and TDMAA precursors suffer from lower yield and poor film quality as compared with the TMA precursor. 19 Therefore, a novel approach toward the realization of AS-ALD without the need for any SAMs and inhibitors is highly favorable to prevent the disadvantages including time consumption, poor thermal stability, selectivity loss, and the limitation of precursors.…”

“…Furthermore, the method encounters the following challenges including time consumption for SAM deposition, poor thermal stability for polymer-based inhibitors, and selectivity-loss for SMI. ,,,, The AS-ALD based on SMI even restricts the use of precursors. For instance, trimethylaluminum (TMA, which is a commonly used ALD precursor) has to be replaced by dimethylaluminum isopropoxide (DMAI) or tris­(dimethylamino)aluminum (TDMAA) to prevent selectivity loss . However, the DMAI and TDMAA precursors suffer from lower yield and poor film quality as compared with the TMA precursor .…”