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

Abstract

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.