Rapid room-temperature synthesis of metal-organic frameworks (MOFs) is highly desired for industrial implementation and commercialization. Here we find that a (Zn,Cu) hydroxy double salt (HDS) intermediate formed in situ from ZnO particles or thin films enables rapid growth (<1 min) of HKUST-1 (Cu3(BTC)2) at room temperature. The space-time-yield reaches >3 × 10(4) kg·m(-3)·d(-1), at least 1 order of magnitude greater than any prior report. The high anion exchange rate of (Zn,Cu) hydroxy nitrate HDS drives the ultrafast MOF formation. Similarly, we obtained Cu-BDC, ZIF-8, and IRMOF-3 structures from HDSs, demonstrating synthetic generality. Using ZnO thin films deposited via atomic layer deposition, MOF patterns are obtained on pre-patterned surfaces, and dense HKUST-1 coatings are grown onto various form factors, including polymer spheres, silicon wafers, and fibers. Breakthrough tests show that the MOF-functionalized fibers have high adsorption capacity for toxic gases. This rapid synthesis route is also promising for new MOF-based composite materials and applications.

Area-selective thin film deposition is expected to be important in achieving sub-10 nm semiconductor devices, enabling feature patterning, alignment to underlying structures, and edge definition. Atomic layer deposition (ALD) offers advantages over common chemical vapor deposition methods, such as precise thickness control and excellent conformality. Furthermore, several ALD processes show inherent propensity for substrate-dependent nucleation. For example, tungsten ALD using SiH 4 (or Si 2 H 6 ) and WF 6 is more energetically favorable on Si than on SiO 2 , but selectivity is often lost after several ALD cycles. We show that modifying the W ALD process chemistry can decrease the W nucleation rate on SiO 2 , thereby expanding the ALD "selectivity window". Specifically, we find that adding H 2 during the WF 6 dose step helps passivate SiO 2 against W nucleation without modifying W growth on silicon. Surface characterization confirms that H 2 promotes fluorine passivation of SiO 2 , likely through surface reactions with HF produced in the gas phase. This passivation affords at least 10 additional W ALD cycles, corresponding to ∼6 nm of additional W growth, before substantial nucleation occurs on SiO 2 . We show that reactant modification also reduces undesirable nucleation due to substrate proximity or loading effects in patterned film growth. Further understanding of ALD reaction chemistry and film nucleation will lead to improved selective metal and dielectric film deposition, enabling ALD bottom-up patterning.

Fiber@ALD@MOF structures fabricated via ALD and layer-by-layer MOF synthesis show good conformality and high adsorption capacity.

Controlled thin film etching is essential for further development of sub-10 nm semiconductor devices. Vapor-phase thermal etching of oxides is appealing for achieving highly conformal etching of high aspect ratio features. We show that tungsten hexafluoride (WF6) can be used to selectively etch amorphous TiO2 films versus other oxides including Al2O3. Chemical vapor etching (CVE) of TiO2 by WF6 was studied with quartz crystal microbalance (QCM), spectroscopic ellipsometry, X-ray photoelectron spectroscopy (XPS), and thermodynamic modeling. The XPS results show evidence for a WO x F y layer that forms on of the TiO2 films during the etch process, which may act as a surfactant layer to help enable fluorination of the TiO2. Direct CVE of TiO2 by WF6 is strongly temperature dependent, where etching proceeds readily at 220 °C, but not at T ≤ 170 °C. This is consistent with thermodynamic modeling showing that the etching rate is determined by the volatilization of metal fluoride and WF2O2 product species. We also show that, at low temperature, BCl3 can be used as a coreagent with WF6 to achieve self-limiting atomic layer etching (ALE) of TiO2. At 170 °C, the rate of ALE saturates at ∼0.6 Å/cycle, which is ∼2× the rate of TiO2 ALD at the same temperature. Experimental QCM analysis shows selectivity for TiO2 ALE vs Al2O3 as predicted by thermodynamic modeling. We also demonstrate and describe how etching reactions during initial cycles can differ from those during steady-state ALE, and we draw a physical analogy between rate evolution in ALE and well-known rate evolution during nucleation in atomic layer deposition (ALD). This work expands understanding of surface reactions in CVE and ALE and the range of reactants and materials that can be active for advanced thermal ALE processing.

While metal‐organic frameworks (MOFs) show great potential for gas adsorption and storage, their powder form limits deployment opportunities. Integration of MOFs on polymeric fibrous scaffolds will enable new applications in gas adsorption, membrane separation, catalysis, and toxic gas sensing. Here, we demonstrate a new synthesis route for growing MOFs on fibrous materials that achieves high MOF loadings, large surface areas and high adsorptive capacities. We find that a nanoscale coating of Al2O3 formed by atomic layer deposition (ALD) on the surface of nonwoven fiber mats facilitates nucleation of MOFs on the fibers throughout the mat. Functionality of MOFs is fully maintained after integration, and MOF crystals are well attached to the fibers. Breakthrough tests for HKUST‐1 MOFs [Cu3(BTC)2] on ALD‐coated polypropylene fibers reveal NH3 dynamic loadings up to 5.93 ± 0.20 mol/kg(MOF+fiber). Most importantly, this synthetic approach is generally applicable to a wide range of polymer fibers (e.g., PP, PET, cotton) and MOFs (e.g., HKUST‐1, MOF‐74, and UiO‐66).