Atomic Layer Deposition of High Quality HfO₂Using In-Situ Formed Hydrophilic Oxide as an Interfacial Layer

Abstract

High-quality HfO 2 cannot be grown directly on Si substrate using atomic layer deposition (ALD), and an interfacial oxide layer is needed. Traditionally, interfacial oxide layer is formed either in SC1 solution (2 NH 4 OH: 4 H 2 O 2 : 200 H 2 O) or by ozonated water spraying. A highly hydrophilic SiO 2 interfacial layer was in-situ formed in the ALD chamber using 1 cycle of ozone and water. The HfO 2 deposited on this interfacial layer showed great growth linearity. The gate leakage current is comparable to that formed using chemical oxide as the interfacial layer. The capacitance-voltage (C-V) curves have negligible frequency dispersion and hysteresis, which suggest high quality in both the interface and electrical properties. The in-situ formation of hydrophilic interfacial layer have advantages over the traditional interfacial layer. This might be useful for formation of interfacial layer on sophisticated 3-D MOS structures such as FinFETs and nanowire FETs. In addition, the chemical oxidation step can be eliminated from the integrated circuits manufacturing processes, which is economically beneficial to the industry. After a decade of investigation, atomic layer deposition (ALD) of high dielectric constant (high-k) material HfO 2 became the mainstream manufacturing processing in semiconductor industry. This is because the superior quality of HfO 2 films obtained by ALD. ALD provides precise control of film thickness and uniformity at the atomic scale, due to its self-limiting surface reaction. However, not all surfaces are suitable for ALD deposition.Extensive work has been done to explore the proper interface conditions for ALD of metal oxides. It is widely accepted that non-oxide like Si surface creates barrier for initial cycles of ALD, results in growth incubation period.1-3 Researchers such as E. P. Gusev, etc. and R. L. Puurunen, etc. explored the ALD nucleation of ZrO 2 , Al 2 O 3 , TiO 2 and HfO 2 on Si surface, and proved that comparing to nucleation on SiO 2 surface, nucleation on H-terminated Si surface is characterized by non-uniformity, island-like morphology, poor metal oxide qualities, and metal diffusion at high temperature.4-11 Plus, underlying SiO 2 would grow at the Si/metal oxide interface at moderate temperature, which is harmful to the scaling of MOS devices.12,13 This has been proved by infrared spectroscopy.14 There are also researches on nucleation of HfO 2 on Si (110) and Si (111), 15 and Ge surface, 16,17 which is a potential substrate material with high mobility. L. In this work, we report an ALD-based in-situ formation of SiO 2 interfacial layer using one cycle of ozone and water. The interfacial layer formed is highly hydrophilic, and the ALD HfO 2 grown on this interfacial layer has comparable qualities to HfO 2 grown on SC1 chemical oxide. The interfacial layer was in-situ formed in the ALD chamber. This method might be used in sophisticated 3-D MOS structures because ALD allows molecules to be deposited on the surface that cannot be accessible using other methods. In addition...

Chemically stable artificial SEI for Li-ion battery electrodes

“…The deposition rate (1.25 Å /layer) was calculated by the slope of the growth line, and it matches well with previous studies of HfO 2 growth. 26,27,29,30 Fig . 2 shows the cycling performance of bare Si electrodes, Si coated with 5 layers (0.63 nm), 10 layers (12.5 nm), and 20 layers (25.1 nm) of HfO 2 under the constant current with a charge/discharge rate equivalent to C/3 (C ¼ 3600 mA/g).…”

“…HfO 2 has been widely used as high-k dielectrics in the semiconductor industry. Moreover, HfO 2 is known for its stability under various conditions, 25,26 which may be desirable for LIB applications. We use X-ray photoelectron spectroscopy (XPS) to demonstrate the stability of HfO 2 coatings by comparing the cycle-aged electrode coatings with freshly prepared coated electrodes.…”