In situ study of the atomic layer deposition of HfO2 on Si

Abstract

Physical and electrical characteristics of atomic-layer deposition-HfO2 films deposited on Si substrates having different silanol Si-OH densities J. Vac. Sci. Technol. A 31, 01A132 (2013); 10.1116/1.4769206 Low temperature growth of high-k Hf-La oxides by remote-plasma atomic layer deposition: Morphology, stoichiometry, and dielectric properties J. Vac. Sci. Technol. A 30, 01A147 (2012); 10.1116/1.3665419 X-ray photoelectron spectroscopy and ultraviolet photoelectron spectroscopy investigation of Al-related dipole at the HfO 2 / Si interface J. Appl. Phys. 105, 024102 (2009); 10.1063/1.3066906 Photoelectron spectroscopic analysis of Hf-silicate/ Si O 2 ∕ Si stacks deposited by atomic layer chemical vapor deposition J.The authors investigated in situ the initial stages of the atomic layer deposition (ALD) growth of HfO 2 on Si(001)/SiO 2 substrates by using tetrakis-di-methyl-amino-Hf and H 2 O as precursors. The surface morphology and the chemical and electronic properties of HfO 2 ultrathin films were studied after each ALD cycle by surface-sensitive techniques. Atomic force microscopy image analysis was performed by analyzing the height-height correlation function (HHCF), the root mean square surface roughness, and the surface fractal dimension, as function of the number of ALD cycles. Parameters directly related to HHCF, e.g., surface width, correlation length, local slope, and roughness exponent, were calculated and used for determination of scaling exponents. A complex behavior of all parameters up to the eighth ALD cycle was evidenced. High-resolution synchrotron radiation photoemission spectroscopy was applied to characterize the chemical nature of Si/SiO 2 /HfO 2 interface. Changes arising in the Si 2p, O 1 s, and Hf 4f core level lines after each ALD cycle up to the complete formation of two layers of HfO 2 were observed. The thickness of the growing HfO 2 layer was calculated to estimate the growth per cycle to approximately 0.1 nm/cycle. By means of ultraviolet photoemission spectroscopy, variations of valence band maximum and secondary electron cutoff after each ALD cycle were observed and the presence of an interfacial dipole was pointed out. Finally, the loss function onset of electron energy loss spectroscopy changed during ALD because of bandgap variations from SiO 2 to HfO 2 . By combining all experimental results a new and fully comprehensive growth model of ALD during the initial stages was developed.

Atomic Layer Deposition of Crystalline MoS2 Thin Films: New Molybdenum Precursor for Low‐Temperature Film Growth

“…The small grain size and considerable roughness make it difficult to determine from the SEM and AFM images when a continuous or closed film is formed, and although the morphology is also a challenge for AFM roughness measurements, the small decrease in roughness between 750 and 1000 cycles may indicate the formation of a continuous film, as demonstrated by the simulations of ALD film growth by Nilsen et al [66,67] as well as experimental observations on HfO 2 [68] and Pt [69] ALD films, for example. Additional information on the surface morphology can be obtained by examination of line profiles taken from the AFM images (Figure 3d).…”

Advanced measurement and diagnosis of the effect on the underlayer roughness for industrial standard metrology

“…2b,c. An oxygen plasma treatment was conducted after surface etching because the hydrogen-terminated Si surface shows poor nucleation and forms a nano-island morphology during the atomic layer deposition (ALD) process 23,32–35 . An HfO 2 layer was deposited onto the surface-treated Si wafers using ALD equipment (Nano-ALD2000; IPS, Pyeongtaek, Korea) because the insulating film of the mass-produced wafer is a 3 nm thick hafnium oxide film, as shown in Supplementary Fig.…”

In situ synchrotron based x-ray techniques as monitoring tools for atomic layer deposition

“…There are however several examples of the use of XPS as in vacuo technique, meaning that the sample gets transferred from an ALD chamber to an XPS analysis chamber under UHV conditions. 37,38,[42][43][44][45] However, the development of high pressure XPS and ambient pressure XPS systems, as are currently pioneered for in situ studies during catalysis, could make in situ XPS possible under ALD conditions. 73 …”