Krzysztof Kolanek

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

The authors investigated in situ the initial stages of the atomic layer deposition (ALD) growth of HfO2 on Si(001)/SiO2 substrates by using tetrakis-di-methyl-amino-Hf and H2O as precursors. The surface morphology and the chemical and electronic properties of HfO2 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/SiO2/HfO2 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 HfO2 were observed. The thickness of the growing HfO2 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 SiO2 to HfO2. By combining all experimental results a new and fully comprehensive growth model of ALD during the initial stages was developed.The authors investigated in situ the initial stages of the atomic layer deposition (ALD) growth of HfO2 on Si(001)/SiO2 substrates by using tetrakis-di-methyl-amino-Hf and H2O as precursors. The surface morphology and the chemical and electronic properties of HfO2 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/SiO2/HfO2 interface. Changes arising in the Si 2p, O 1 s, and Hf ...

Fullerene based materials for ultra-low-k application

Fullerene-based materials are considered to be a candidate for ultra-low-k material applications. We have incorporated fullerene C60 into a siloxane material by means of the sol-gel method. Thickness of obtained film was investigated by atomic force microscope, dielectric constant was measured by the capacitance-voltage characterization (CV). Interactions between the components within the films were investigated by using X-ray photoelectron spectroscopy and near edge X-ray absorption fine structure spectroscopy. We found that the ratio of carbon, oxygen and silicon atoms within obtained film equals 2.7∶1.9∶1. The microscopic and CV investigations show that the samples composition is inhomogenous although the fullerenes concentration within the material is low. However, dielectric constant is in the range of 2.3 to 2.5.

Height distribution of atomic force microscopy images as a tool for atomic layer deposition characterization

The authors propose the analysis of surface height histograms as a tool for the atomic layer deposition (ALD) growth characterization in the initial stage of the process. ALD of HfO2 on a Si(100)/SiO2 substrate was investigated in situ by ultra high vacuum atomic force microscope working in noncontact mode. The ALD cycles, made by using tetrakis-di-methyl-amido-Hf and H2O as precursors, were performed at 230 °C. After each ALD cycle, the relation between the film growth and the root mean square surface roughness was studied. Parameters equivalent to HfO2 layer thickness, coverage, and surface roughness of the substrate and deposited material can be calculated in the proposed routine.

In situ measurements of the atomic layer deposition of high-k dielectrics by atomic force microscope for advanced microsystems

We investigated in situ the atomic layer deposition (ALD) of high-k dielectrics for advanced microsystems by ultra high vacuum (UHV) atomic force microscope (AFM). With our equipment we examined the surface topography of the substrate and the thin high-k films without breaking the vacuum and therefore without contaminating the sample with external agents. Following the full analysis of the Si(001)/SiO2 substrates we started the ALD process. After each ALD cycle using tetrakis-di-methyl-amido-Hf (TDMAHf), and H2O as precursors, we studied the relation between the film growth and the root mean square surface roughness, surface fractal dimension and correlation length. Additional information about the ALD was extracted from the statistical description of the surface by the height histogram together with the surface skewness and kurtosis parameters. The in situ studies of the ALD process with the UHV/AFM system were correlated with the experiments performed by means of synchrotron radiation photoelectron spectroscopy for understanding the fundamental properties of the ALD of high-k thin films on Si(001)/SiO2 substrates.