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Institute
BTU
We report on a novel system for in-situ atomic layer growth (ALD) of high-k dielectric films. First results were obtained for Hf-oxide samples by using Hf-tetrachloride as precursor and water as oxidizer. We compare the photoelectron spectra of Si2p, O1s and Hf4f of our in-situ prepared films with samples (ex-situ) prepared by industrial ALD reactors and discuss similarities and differences observed in the core level spectra of the various samples by considering the different growth conditions.
In this study we produced 3-aminopropyltrimethoxysilane based hybrid nanocomposites using fullerene derivative [6,6]–phenyl–C61–butyric acid methyl ester (PCBM) as nanodopants. Additionally,
we modified obtained material with incompletely condensed cage polyhedral oligomeric silsesqiuox-anes (POSS) in order to improve its properties. Thin films were deposited by means of the spin-coating method. The films were characterized by atomic force microscopy (AFM), X-ray photoelectron
spectroscopy (XPS) and capacitance–voltage (CV) measurements. We observed that a properly chosen
PCBM concentration may be a crucial factor to obtain high quality APTMS based films by the spin-coating technique. XPS revealed the presence of the C-NH-C species within POSS containing films
indicating chemical interaction between the amino group of APTMS and the POSS molecules. AFM results suggest that at high POSS monomer concentration in the range of 1% the creation of fractal-shaped aggregates takes place. The CV characterization of the samples exhibits a decrease of the APTMS based films dielectric constant due to the POSS and PCBM contribution. The combination of the applied methods delivers complementary information concerning the properties of the analyzed films.
We have investigated the growth of Hf-oxide on Si by means of photoemission and X-ray absorption spectroscopy using synchrotron radiation at Bessy, Berlin. The Hf-oxide layers were grown via atomic layer deposition (ALD) using an in-situ ALD reactor attached to the investigation chamber. The XPS and XAS spectra were measured after every deposition cycle by transferring the sample into the investigation chamber without breaking the vacuum. From the experimental data we have obtained information about the early stages of the Hf-oxide growth, concerning in particular the reactivity of the interface with Si. Due to the possibility to study the layers after every cycle and with different oxidation parameters without exposing them to contaminants, the in situ investigation revealed to be a very important method to understand the growth properties of Hf-oxide.
The C60 fullerenes and some of its -OH, -CF3 and -Cl derivates are candidates for application as ultra-low-k insulators in the semiconductor industry. Future preparation of thin films based on these materials requires the stability of the substituted fullerenes against chemical handling and processing steps. The latter issue was addressed by our NEXAFS studies that were done by synchrotron radiation at the beam line U49/2-PGM2 at BESSY II. Performed were the C K-edge NEXAFS studies in total fluorescence and total electron yield modes. The C60 based films were deposited on silicon by spraying from solutions. The influence of the different substitutional groups with C60 molecules was studied. The data were compared to the reference spectra of a pure C60 film. For C60(OH)24, C60-Cl2 and C60(CF3)12 a variance of the intensity of the π*-resonance as well as shift to higher energies of 0.5 eV (-OH), 0.6 eV (-F), 0.7 eV (-Cl) were observed. The results confirm the necessary stability of the used C60 derivatives and shall be used for optimization of the film deposition chemistry and conditions.
A model has been developed to simulate electromigration degradation in an interconnect segment in two
dimensions using finite differences. The model was deployed on a parallel computer to statistically assess the lifetimes. The simulation takes into account the diffusion paths for electromigration mass transport along the grain boundaries and the capping layer. The microstructure is generated with a Monte Carlo
algorithm, using a modified Potts model. Diffusivities along the grain boundaries and the capping layers
were applied as multiples of a base diffusivity and were statistically scattered. The simulation results correlate well with electromigration tests.