HfO₂ Area Selective Deposition via Substrate-Dependent Area Selective Atomic Layer Etching

The development of new material–substrate systems and methods for area selective deposition (ASD) is vital to the manufacturing of next-generation microelectronics. Atomic layer deposition (ALD) and atomic layer etching (ALE) have been integrated to achieve ASD by reintroducing the initial nucleation delay during ALD on the surface, where no growth is desired, but many ALD processes show minimal nucleation delay on some materials. This work demonstrates the integration of HfO2 thermal ALD (TDMAHf and H2O) and thermal ALE (WF6 and BCl3) for HfO2 ASD on Co/Si–H versus Ru/SiO2 via the substrate-dependent film structuring and etching rate. At 275 °C, the quartz crystal microbalance shows the same growth rate on Co and Al2O3 during HfO2 ALD, but significantly more HfO2 is removed on Al2O3 than Co during HfO2 ALE before etching stops on each surface. Ultrathin HfO2 films deposited at 275 °C are amorphous on SiO2 and partially structured on Co. After annealing at 600 °C, the ⟨−111⟩ monoclinic crystalline plane is observed in HfO2 on SiO2 and Co with additional orthorhombic and tetragonal crystalline planes observed on only Co. Spectroscopic ellipsometry and transmission electron microscopy show >4 nm HfO2 selectively grown via integrated ALD/ALE on metal versus dielectric without the use of organic nucleation inhibition. This work provides novel insights into chemical patterning of dielectric materials via integrated ALD/ALE and low-temperature control of structured materials for advanced atomic scale processing.