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The nucleation of TaCN films during plasma enhanced atomic layer deposition (PEALD) using pentakis-(dimethylamino)tantalum (PDMAT) in combination with H2/Ar plasma was investigated on several substrate surfaces by X-ray photoelectron spectroscopy (XPS) without vacuum break. A cluster tool combining a process reactor with a surface analysis unit under high vacuum conditions ensures a direct qualification and quantification of the chemical surface composition by XPS starting from the very first precursor pulse. Due to the high sensitivity of in vacuo XPS measurements, tantalum can be detected at the substrate surface already after the very first precursor pulse of the PEALD process. The amount of adsorbed tantalum precursor molecules on the silicon oxide surface is much higher compared to the H-terminated Si and low-k surfaces. The early cycles are characterized by the onset of Ta O bonds. A Ta O interface layer grows on the substrate surface until all the reactive OH-groups are consumed. This is followed by the emergence of Ta C and Ta N bonds when the homogenous growth mode begins. The PEALD nucleation of TaCN was also investigated on low-k substrates (SiCOH). The homogeneous film body on all substrates consist of Ta- carbide -nitride, and -oxide compounds. In summary, we obtained precise information about the initital tantalum precursor adsorption on several substrate materials and explored the capability to enhance the initial growth on low-k substrates. These examples demonstrate as well that in-vacuo XPS measurements are ideally suited for studying film growth nucleation.

The copper electrochemical deposition (Cu-ECD) filling capability of high aspect ratio through silicon vias (HAR-TSVs) and homogeneity over 300 mm wafers were investigated on a film stack of thermal ALD (thALD) TaxNy barrier with thermal ALD Ru seed in comparison to TixNy barrier with a standard Cu i-PVD seed layer using a commercial 300 mm plating tool. As a first step, Cu-ECD was conducted on wafers with TSV blind holes with aspect ratios (AR) of 10 to 12. To achieve this, a thermal ALD film stack of approximately 6 nm TaxNy and 9 nm Ru (with a sheet resistance of [25.6 ± 1.4] Ω/ϒ) were deposited at 250 °C. The reactants for the barrier layer were (tert-butylimido)tris(diethylamino)tantalum(V) (TBTDET) and ammonia (NH3) as co-reactant. For the Ru seed layer deposition (ethylcyclopentadienyl)(pyrrolyl)ruthenium(II) (ECPR) and molecular oxygen as co-reactant were used supplemented by a hydrogen purge step after every third ALD cycle. The corresponding ALD growth was observed during the entire process by in-situ real-time spectroscopic ellipsometry (irtSE). Blister-free deposition and satisfactory film stack adhesion with no delamination was verified ex situ by scanning electron microscopy (SEM). The deposited copper inside the TSVs was analyzed by focused ion beam (FIB) imaging and X-ray tomography. The Cu ECD filling capability in HAR-TSVs was shown on a film stack of thALD TaxNy thALD Ru seed using a commercial industry standard 300 mm plating tool. A novel blister-free ultra-thin Ru ALD film having good adhesion properties and unique advantages, e. g. high conformity in high-aspect-ratio through-silicon vias large-scale film uniformity over 300 mm wafers, as well as good reproducibility was developed.

In this work, the precursor tert -butylimido-tris-ethylmethylamido-tantalum (TBTEMT) was applied for the atomic layer deposition (ALD) of tantalum oxide (Ta 2 O 5 ) thin films for the first time. Water was used as the second reactant. A self-limiting, and hence, ALD-like film growth was confirmed in the temperature range from 100 to 300 °C. The temperature window of this process extends from 250 to 300 °C and features a growth rate of about 0.56 A/cycle. For lower temperatures, the growth rate increases gradually up to 0.92 A/cycle at 100 °C. At a deposition temperature of 200 °C, the process showed perfect layer-by-layer growth with 0.64 A/cycle and without any noticeable incubation period on both silicon with native oxide and hydrogen-terminated silicon. In addition, the conformal coating of structures with an aspect ratio of 40:1 is demonstrated as well. According to XPS analyses, the films are oxygen rich (Ta:O ratio around 0.34 ± 0.01 for films grown at 150–300 °C) and contain a significant amount of carbon (6 ± 2 at.%) and some nitrogen ( 3 , 2.25 and 31, respectively. Films grown at 200 °C are amorphous and smooth. They exhibit a film density of 7.8 ± 0.1 g/cm 3 , a refractive index of 2.17 (at 550 nm) and a dielectric constant of 26 ± 1. However, the films suffer from high leakage currents (> 10 − 4 A/cm 2 ). In addition, electrical measurements revealed the formation of an interfacial layer between the Ta 2 O 5 films and bare silicon. By using substrates with a thin thermally grown silicon oxide, the leakage could be reduced by three orders of magnitude. Post-deposition annealing at 800 °C in nitrogen resulted in the crystallization of the Ta 2 O 5 films, which is also accompanied by an increase in film density and refractive index. Moreover, the crystallized films exhibit an enhanced dielectric constant of 48 ± 2. Electrical measurements revealed the growth of an interfacial layer with an equivalent oxide thickness of around 2.4 nm due to the 800 °C annealing. While this interfacial layer degrades the effective permittivity of the dielectric ( e.g. 20.5 ± 0.5 for a 20 nm Ta 2 O 5 film), it also causes a reduction of the leakage currents by more than three orders of magnitude ( e.g. to 1·10 − 7 A/cm 2 for a 20 nm Ta 2 O 5 film).

Aluminum oxide (Al 2 O 3 ) thin films grown by atomic layer deposition (ALD) at low temperatures exhibit low film densities, and therefore, may not meet the requirements for demanding barrier applications. In this work, a novel approach is presented to obtain improved film densities by short-term thermal treatments while keeping the overall low thermal budget of the deposition process. For that purpose, millisecond flash lamp annealing (FLA) was directly integrated into the ALD process, enabling the thermal treatment of the growing films not only subsequent to the deposition process but already right during the stage of film growth. By applying this in situ FLA after every single ALD cycle, the density of Al 2 O 3 films grown at a substrate temperature of 75 °C could be increased from 2.8 g/cm 3 up to 3.1 g/cm 3 . However, this 10% increase in film density was not related to an ordinary film densification. Instead, the studies reveal that in situ FLA promoted an enhanced and denser film growth, most probably by directly affecting the surface chemistry of the ALD process. The enhanced film growth was observed in terms of a 25% increase in the mass gain per cycle, reaching a level comparable to pure ALD at a deposition temperature of 250 °C. Furthermore, the application of in situ FLA also resulted in an improved film composition, increased refractive indices, higher dielectric constants and reduced leakage currents. The presence of molecular hydrogen during the FLA treatments led to an even further improved mass gain per cycle, film composition and dielectric constant. Despite the FLA treatments the films remained amorphous. In addition, the film densities obtained by the application of in situ FLA were not achieved by conventional post deposition annealing with temperatures up to 600 °C.

Atomic layer deposited nanolaminates of alternating AlOx and TiOx thin-films are investigated as moisture barriers for organic electronic devices. Direct encapsulation on organic light emitting diodes (OLEDs) is tested in aging experiments and compared to calcium corrosion tests of equivalent barrier films. This allows for a direct assessment of moisture barrier performance in simple as well as more complex systems. Thickness variations are performed for the nanolaminate single and total layer thickness, with an optimum single layer thickness of 1–2 nm observed. This correlates to the maximum number of dyads once completely closed single layers are produced. For large single layer thickness and low dyad count, strong lateral diffusion from the edges occurs in the OLEDs, which likely correlates to poor mechanical stability. At optimum single layer thickness, barriers remain mechanically and chemically stable up to 100 nm total thickness. OLEDs encapsulated with such nanolaminate barriers show no significant degradation after 2500 h of continuous aging.

Microcrystalline silicon thin-film solar cells were fabricated at high absorber layer deposition rates from 1.0 up to 2.5 nm/s. High efficiencies of 9.6% (1.0 nm/s) and 8.6% (2.5 nm/s) were achieved using a very high frequency (VHF) of 140 MHz for the deposition of all silicon layers (p–i–n). Using such a high frequency in the VHF band is unique in the field of thin-film silicon solar cells. The efficiencies obtained especially at very high rates belong to the highest reported efficiencies so far for this technology. This shows that VHF deposition with frequencies larger than 100 MHz is very well suited for a highly productive solar cell fabrication. The VHF power homogeneity problem can be solved by using for example the linear plasma source concept developed at FAP GmbH/TU-Dresden. We show that the efficiency at very high rates of 2.5 nm/s is limited by an increased crack formation in the absorber layer.

Organic devices like organic light emitting diodes (OLEDs) or organic solar cells degrade fast when exposed to ambient air. Hence, thin-films acting as permeation barriers are needed for their protection. Atomic layer deposition (ALD) is known to be one of the best technologies to reach barriers with a low defect density at gentle process conditions. As well, ALD is reported to be one of the thinnest barrier layers, with a critical thickness – defining a continuous barrier film – as low as 5–10nm for ALD processed Al2O3. In this work, we investigate the barrier performance of Al2O3 films processed by ALD at 80°C with trimethylaluminum and ozone as precursors. The coverage of defects in such films is investigated on a 5nm thick Al2O3 film, i.e. below the critical thickness, on calcium using atomic force microscopy (AFM). We find for this sub-critical thickness regime that all spots giving raise to water ingress on the 20×20μm2 scan range are positioned on nearly flat surface sites without the presence of particles or large substrate features. Hence below the critical thickness, ALD leaves open or at least weakly covered spots even on feature-free surface sites. The thickness dependent performance of these barrier films is investigated for thicknesses ranging from 15 to 100nm, i.e. above the assumed critical film thickness of this system. To measure the barrier performance, electrical calcium corrosion tests are used in order to measure the water vapor transmission rate (WVTR), electrodeposition is used in order to decorate and count defects, and dark spot growth on OLEDs is used in order to confirm the results for real devices. For 15–25nm barrier thickness, we observe an exponential decrease in defect density with barrier thickness which explains the likewise observed exponential decrease in WVTR and OLED degradation rate. Above 25nm, a further increase in barrier thickness leads to a further exponential decrease in defect density, but an only sub-exponential decrease in WVTR and OLED degradation rate. In conclusion, the performance of the thin Al2O3 permeation barrier is dominated by its defect density. This defect density is reduced exponentially with increasing barrier thickness for alumina thicknesses of up to at least 25nm.

In this study, PVD Ru-Mn composites were investigated in terms of major concerns that arise with the introduction of a new type of barrier. First, the Cu diffusion barrier performance after annealing at 600^oC and under subsequent BTS of +2MV/cm, 250^oC was investigated on SiO"2, and after 350^oC annealing on low-k dielectrics. Ru-Mn films proved to serve as outstanding Cu diffusion barrier over a wide range of Mn content. Second, the origin of the barrier performance was investigated using TEM, EELS and XPS depth profiling techniques, revealing the stuffing of grain boundaries as barrier mechanism. Third, Cu plating on damascene wafers applying a Ru-Mn seed layer was tested, and also the Cu adhesion thereon, resulting in a complete feature fill and excellent Cu wetting behavior. Fourth, the blocking of oxygen diffusion was examined, leading to a performance comparable to PVD TaN. Finally, the Mn content inside Ru was reduced down to 1at.% without compromising the superior material properties.

The initial growth behavior of ruthenium during the thermal-activated atomic layer deposition (ALD) using [(ethylcyclopentadienyl)(pyrrolyl)ruthenium(II)] (ECPR) and molecular oxygen was investigated in a cluster tool combining an ALD reactor with a surface analysis unit under high vacuum conditions. A direct qualification and quantification of the chemical surface composition by X-ray photoelectron spectroscopy (XPS) and a determination of the surface topography by atomic force microscopy (AFM) were conducted in the course of the ALD cycles without vacuum break. XPS revealed a substrate-inhibited Ru growth on a hydrogen-terminated silicon surface, which was preceded by an incubation period of 20ALD cycles. The Si surface oxidized during the first 50cycles. AFM measurements showed a roughness maximum around the 40th ALD cycle, which suggested an island growth mode and thus corresponded with the substrate inhibition. As verified from the AFM data with an analytical model by Nilsen et al. the Ru islands coalesced between the 40th and 50th ALD cycle. The ALD growth initiation of Ru was also investigated on aluminum oxide and tantalum nitride. XPS revealed a similarly inhibited growth behavior on all the investigated substrates. However, the ECPR adsorption during the very first Ru precursor pulse differed as the amount of chemisorbed Ru on the NH"y-terminated TaN"x(O, C) surface was much higher compared to the OH-terminated Al"2O"3 and the H-terminated Si surface. Summarizing, we demonstrated that in-vacuo XPS and AFM as well as the combination of both are ideally suited for studying the ALD growth initiation of Ru. Furthermore, we provided important chemical information about the initial Ru precursor adsorption on several foreign substrate materials, which will direct further investigations towards a non-inhibited Ru growth.

The paper presents atomic layer deposition (ALD) processes and process integration for the deposition of insulating liners, copper diffusion barriers, and seed layers for direct copper plating in high aspect ratio (>20:1) through silicon vias. A TaN-based copper diffusion barrier was deployed on an aluminum oxide insulating liner. The latter has the potential to act also as a dielectric barrier against copper diffusion according to BTS and TVS measurements. Furthermore, ruthenium ALD films applied as seed layers for direct copper plating were deposited with an intermediate annealing step to improve film adhesion and ensure the deposition of thick films without any delamination. The step coverage of the presented ALD processes was confirmed by SEM measurements on cross-sections of coated TSV structures. Finally a subsequent electrochemical deposition (ECD) of copper was conducted revealing the satisfying functionality of the Ru seed layer.

The dependence has been investigated of electrical, optical and structural properties of undoped ZnO films grown on single-crystal c -sapphire substrates by pulsed laser deposition on the substrate temperature in the range between 50 °С and 650 °С. It has been shown that an increase in energy density of laser radiation at the target surface leads to lowering of the temperature of epitaxial growth of zinc oxide films. The surface roughness of the films produced at the substrate temperature of 450 °C does not exceed several monolayers, and the width of X-ray diffraction peaks 2 Θ at half maximum near the lattice site (00.2) makes 0.035°.

Moisture uptake of a benzocyclobutene (BCB) film has been investigated by using the capacitance-time (C-t) measurement method. The change in the permittivity at 80% relative humidity (RH) at room temperature in saturation is about 1.54%. To derive the absolute amount of water molecules from the change in capacitance an appropriate electrical model is required. For the direct measurement of the amount of water molecules in the BCB film gravimetric measurements have been performed at the same environmental conditions by using a quartz crystal microbalance (QCM). In saturation the change in mass induced by the moisture uptake is only about 0.14%. However, the application of the Debye equation using the dipole moment of water vapor yielded an excellent agreement between electrical and physical measurements.

In order to deposit thin films on a substrate several techniques can be used, e.g. chemical vapour deposition, atomic layer deposition or sputter deposition, depending on their specific advantages and disadvantages due to the related application. A significant parameter is the energy incident upon the substrate by the specific technique, especially when the heat capacitance of the substrate is low. Within this paper we analyse the energy transported into a thin wire (few 10 μm in diameter) during a dynamic inline aluminium sputter process in a cylindrical magnetron source. The evoked heating is important for the tensile strength of the wire and uniformity of the sputtered layer. Therefore, mathematical models were created to estimate the energy input into the wire supported by monte-carlo-simulations of the sputtering process using the TRIM-simulation (Transport and Range of Ions in Matter). Measurements with a Langmuir probe and the corresponding deposition rate were used to quantify these models, showing that at an aluminium coating process of a gold wire, the significant energy input is only due to electrons and ions of the processing gas (argon). Using the heat equation based on the sputtering apparatus' parameters, it was also possible to determine the energy input into the wire with in situ electrical resistance measurements. Both methods did show similar results, whereby the resistance results were more stable. The determined energy input made it possible to calculate the temperature profile during the wire-coating process which can be useful for estimations about film diffusion and process optimisation.

Co-sputtered Ru-Ta(N), Ru-W(N) and Ru-Mn composites are investigated in terms of their barrier properties against Cu diffusion. A wide range of stoichiometries is analyzed with regard to crystallization, barrier properties, resistivity, Cu adhesion and direct Cu plating behaviour. All films were annealed at 350^oC and 600^oC in forming gas for 1h and subsequently stressed at elevated temperatures and electrical fields (BTS, 250^oC, 2MV/cm, 30min). The leakage current was monitored during BTS to observe increased leakage due to Cu diffusion. The Cu ions that eventually have passed the barrier and drifted into the dielectric of the MIS test structure were detected and quantified using the triangular voltage sweep method. The addition of 10% W or Ta into a Ru film already leads to a highly improved barrier performance against Cu diffusion, comparable to TaN, as long as the temperatures involved are kept below 350^oC. Outstanding barriers were identified after 600^oC annealing and subsequent BTS, among them Ru"5"0W"5"0", Ru"5"0Ta"5"0 and Ru"9"5Mn"5. However, only Ru"9"0Ta"1"0 and Ru"9"5Mn"5 offer an excellent Cu adhesion and the possibility of direct Cu plating.

Chemical mechanical planarization (CMP) models which are able to make predictions on the chip and feature scale are highly desirable in semiconductor manufacturing. Most of the models proposed in the past years have largely focused on the pattern density and neglected effects of pattern size in planarization. We here propose a new CMP feature scale model that incorporates size effects by considering the roughness of the polishing pad. It is validated by experimental data from CMP test structures containing variations of both pattern-density and -size. The results are applied to ILD- and STI-CMP as particularly important processes in industry. The derived model describes the feature step height and shape evolution with high accuracy throughout the planarization process.

The diffusion barrier properties of PVD Ru and PECVD / PEALD Ru-C films, deposited by RuEtcp"2 precursor and N"2/H"2 plasma, were compared on the basis of bias temperature stress measurements. An MIS test structure was used to distinguish between thermal diffusion induced by annealing and a Cu field drift due to applied electric fields. BTS-CV, TZDB and TDDB measurements revealed that the barrier performance is significantly better for PEALD and PECVD Ru-C films. This improvement is associated with carbon impurities in the Ru films with a concentration in the order of several percent according to ToF-SIMS and ERDA. The TDDB mean time to failure at 250^oC, +5MV/cm was 7s for PVD Ru samples, ~500s for PECVD Ru-C, ~800s for PEALD Ru-C and>3600s for PVD TaN. Triangular voltage sweep measurements at 300^oC, 0.1V/s confirmed the presence of Cu ions inside the SiO"2 for degraded dots, in contrast to the Al reference sample and to PVD TaN, which performed best among all the Cu barriers under test. XRD data suggests that PEALD and PECVD Ru-C films are only weakly crystalline.

Electroplated Cu(Ag) alloy thin films are potential candidates for future electronic devices in terms of lifetime and reliability compared to copper as the state of the art interconnect material. In the present paper we focus on the microstructure of Cu(Ag) alloy films considering the grain evolution as well as silver incorporation and segregation. We show that Ag alloying addition prevents room temperature recrystallization. Thermally induced grain growth occurs mainly between 180 °C and 330 °C. Silver can be incorporated as solid solution into the Cu matrix by up to 0.8 at.% after annealing and even in higher concentrations in the as-deposited state, which is significantly above the equilibrium solubility limit. Precipitations are formed by the continuous mode and can be mainly found at the film surface but also inside the Cu(Ag) grains as ball-shaped particles. Based on our results a reliability improvement is expected by mechanical strengthening due to alloying effects while maintaining a low electrical resistivity and a {111} fiber texture.

By an ALD process with the solid precursors HfCl 4 and (CpCH 3 ) 3 Y and the oxidant water Yttrium doped HfO 2 was deposited on TiN layer on highly doped silicon. The films were analysed by ellipsometry, XRR, RBS and XRD. For the electrical characterisation, capacitance and I-V measurement on MIM structure were used. By doping the HfO 2 with 6.2 at.% Yttrium and annealing the film at 500 °C in N 2 the k-value increased by 60% for a 9.5 nm thick film, the leakage current also increased. The deposited amorphous film crystallises at 450 °C into the cubic phase.

The temperature dependence of the sticking coefficient (SC) of precursor molecules used in atomic layer deposition (ALD) was investigated. Tetrakis(ethylmethylamino) hafnium (TEMAHf) and Pentamethylcyclopentadienyltitan-trimethoxid (Cp*Ti(OMe)(3)) were used in combination with ozone to deposit hafnium dioxide and titanium dioxide films at different substrate temperatures. The SC of TEMAHf was determined at 180, 230, and 270 degrees C. The SC of TEMAHf depends exponentially on the substrate temperature. The activation energy and the pre-exponential factor were obtained for this ALD process. The SC of Cp*Ti(OMe)(3) was determined at 270 degrees C. A possible explanation for the small SC of Cp*Ti(OMe)(3) could be the reduced symmetry of the precursor molecule. Therefore, symmetric precursor molecules and high process temperatures appear beneficial for efficient ALD processes.

Electromigration effects in interconnect metallizations cause a need for materials with superior resistance against electromigration failure but with adequate electrical properties. In principle, Cu(Ag) alloys are potential candidates to become an interconnect material of the next generation of microelectronic devices. Therefore, in the following paper the electroplating of such Cu(Ag) alloys from a sulfuric acid electrolyte solution with varying silver content in a home built deposition tool is presented. Besides the general deposition characteristics, the growth mode of the films and the deposition into trenches will be discussed. The investigations show that Cu(Ag) alloys can be deposited with adequate homogeneity of the film thickness by electroplating. Furthermore, the electrical resistivity is low enough to assure a use of these films for interconnect applications. However, distinct island growth and insufficient trench filling capabilities lead to the fact that the additive composition needs to be optimized for Cu(Ag) thin film electroplating.

For feature sizes smaller than 100nm, proximity effect correction gains more importance in electron beam lithography. Several methods have been proposed for the determination of the proximity parameters, most of them being extensive and time-consuming. This paper investigates the reliability of the doughnut test and specifies the electron backscattering portion with a given resist-process. The functionality of the method for negative resist systems exposed by a variable shaped e-beam writer is shown for the first time. Compared with conventional methods, the modified doughnut test was proven to be a fast, straightforward and reliable method for determining the backscattering proximity parameters when utilized together with sensitive scanning electron microscopy.

Electromigration failure of copper interconnects in microelectronics evokes a need for materials with improved resistance against electromigration effects. Copper-silver alloy thin films are a promising material for the next generation of interconnects and were investigated with respect to their electromigration resistance. The investigations were done by atom drift experiments by means of Blech structures fabricated in single damascene technology with two different Ta-based liner systems. Electromigration induced atom drift could be demonstrated. The resistance against electromigration of Cu(Ag) films appears to be slightly higher than for pure Cu films. However, significant experimental errors are still present. Additionally, de-alloying effects were observed.

Amorphous and microcrystalline silicon single layers and p–i–n solar cells were produced dynamically using an inline deposition system called “line source”. A highly uniform deposition of thin-film silicon layers with layer-thickness variations of less than ±5% was achieved. Amorphous and microcrystalline silicon single junction solar cells were dynamically fabricated with initial efficiencies of 8.3% and 6.3%, respectively. The dynamic deposition rate of these solar cells is 6.75 nm m/min in case of a-Si:H and 3.3 nm m/min for μc-Si:H. In this work it will be shown that an enhancement of the deposition rate up to 15.6 nm m/min during the i-layer deposition of a-Si:H solar cells has only a weak negative influence on the initial efficiencies of the cells. Further on, the effect of substrate velocity on solar cell characteristics of a-Si:H solar cells is investigated. Finally, a productivity estimation of the line source concept is presented.

A method to determine the sticking coefficient of precursor molecules used in atomic layer deposition (ALD) will be introduced. The sticking coefficient is an interesting quantity for comparing different ALD processes and reactors but it cannot be observed easily. The method relies on free molecular flow in nanoscale cylindrical holes. The sticking coefficient is determined for tetrakis(dimethylamino)titanium in combination with ozone. The proposed method can be applied independent of the type of reactor, precursor delivery system and precursors.

To increase the electromigration resistance of copper interconnects copper alloy systems are of interest. In the present paper electrical properties of Cu(Ag) films will be discussed with respect to heat treatment and in comparison to copper and other alloy systems. The investigations show that the electrical resistivity of Cu(Ag) films is very low in comparison to other copper alloy systems. Up to an alloy content of about 2 at.% Ag the International Technology Roadmap for Semiconductors criterion of 2.2 μΩcm (scattering by geometrical constraints neglected) can be fulfilled after heat treatment. The various components of the electrical resistivity will be discussed in detail. The investigations show that grain growth and the redistribution of silver and impurities dominate the electrical resistivity evolution.

The deposition of ultra thin Ta(N) films by ALD is a possibility to achieve conformal film thickness and suitable step coverage for microelectronic applications. Due to the sorption of a precursor molecule to the substrate surface, the chemical interface conditions are important. In the present study selected substrate pretreatments were investigated by in situ XPS and spectroscopic ellipsometry in reference to the amount of carbon containing contamination and oxygen and in reference to the ALD growth rate of Ta(N) films. Furthermore, surface roughness was measured by AFM and will be discussed in dependence on the individual pretreatment and the ALD Ta(N) cycle number.

Ta-N based thin films were grown by thermal atomic layer deposition (ALD) with an alternating supply of the reactant source TBTDET (tert-butylimidotris(diethylamido)tantalum) and NH3 (ammonia). The films were deposited using a newly designed and constructed atomic layer deposition prototype tool combined with several in situ metrology. It was observed that thin films were successfully deposited on a 300mm Wafer with a saturated growth rate of approximately 0.55i?/cycle at 270?C. The as deposited films resulted in the formation of Ta(C)N consisting of 38at% Ta, 32at% N and 10at% C. With in situ spectroscopic ellipsometry (SE) the growing behaviour of the film was investigated and compared to atomic force microscopy (AFM) images.

To avoid plasma induced erosion of chamber hardware, the application of remote plasma sources to activate the etch gases was introduced. We present results on the etch behaviour of titanium nitride (TiN) using mixtures of NF"3, Cl"2 and argon. The gas mixture was excited in a remote plasma source and then routed through a reaction chamber to study the etch behaviour of TiN samples which simulate the situation at the chamber walls. The dependency of the TiN etch rate on temperature, gas flow, composition and pressure was examined. While the temperature (studied in the range 25-300^oC) turned out to be the most sensitive parameter, the general etch rate was mainly dependent on the availability of atomic fluorine. Etch products and NF"3/Cl"2 dissociation have been monitored by quadrupole mass spectrometry and infrared spectroscopy. While NF"3 showed a high decomposition up to 96%, chlorine decomposition was not observed. However the addition of chlorine increased the etch rates up to 260% in the low pressure/low temperature regime. Surface effects of chlorine addition are indicated by X-Ray Photoelectron Spectrometry and REM surface analysis.

The aim of this study is to reduce the amount of harmful substances in the effluent gas in the plasma cleaning process of vacuum chambers by substituting the greenhouse gas SF 6 . We present comparative studies for the optimised cleaning rates which are based on C 4 F 8 / O 2 and NF 3 diluted with He, Ar and N 2 in comparison to SF 6 /O 2 . Since the deposition of amorphous silicon (a-Si) requires a temperature of 200-250 °C in the vacuum chamber, the cleaning process has to match with these conditions, creating especially limitations on the maximum plasma power that can be used. The results for C4F 8 /O 2 turn out to be unsatisfactory. NF 3 however appears to be more promising. We find that the utilisation of NF 3 as etching gas in the vacuum chamber approaches up to 90% and the dilution can be up to 80%. This high dilution and utilisation demonstrates also that cleaning with NF 3 can be cheaper than cleaning with SF 6 even though NF 3 is much more expensive than SF 6 .

Aluminum oxide was deposited on arsenic doped silicon, using atomic layer deposition (ALD) with either a silicon oxide or a silicon nitride interface. The physical properties of these films were investigated by elastic-recoil-detection, X-ray-photoelectron-spectroscopy and transmission electron microscopy. Special focus was given to contamination of the film and the interface, crystallization and temperature effect on diffusion. The films remained stoichiometric and did not have Al–Al clusters, even post annealing steps. Evidence of diffusion of silicon and arsenic into the dielectric and of aluminum from the film was found. Carbon and hydrogen were seen in the film and at the interface as well, whereas hydrogen diffused out of the film to some extent due to anneal. Carbon content in the layer was reduced by using O3 as oxidant. Grain size of crystalline Al2O3 films was in the order of film thickness.

The integration of ultra low k materials in copper damascene architecture is one of the main issues in finding microelectronic-process-compatible dielectric materials. The aim of this paper is to show the integration conformity with common equipment and process steps using a PECVD (plasma enhanced chemical vapor deposition) CF polymer ultra low k material in a Cu single damascene architecture (Proceedings of the Advanced Metallization Conference, 2002). The intermetal dielectric low k material used in the described structures has 2.1≤k≤2.3 (k depends on deposition process parameters [Microelectron. Eng. 50 (2000) 7-14]) and the copper was deposited by a metal organic chemical vapor deposition process. After chemical mechanical polishing the structures were characterized by scanning electron microscopy and electrical measurements.

The objective of our investigations was to develop a new etching process, which accomplished well defined positive etch profiles in silicon. Using this so-called PPE-process (Positive Profiles Etching process) we realized patterns in silicon with tilt angles of the sidewalls between 60 and 88° and an etch depth up to 200 μm. Etch rates between 3 and 5 μm/min can be achieved and a large number of process parameters enables the variation of the etch profiles in a wide range. Based on these results we could create complex etch profiles by a combination of several silicon etching processes according to application-oriented demands.

Sputter deposited Ta and TaN single layers of 10 nm thickness as well as graded TaN/Ta and Ta/TaN/Ta layer stacks that act as diffusion barriers for Cu metallization were investigated after annealing at temperatures between T an =300 and 700 °C. By means of glancing angle X-ray diffraction, glow discharge optical emission spectroscopy and transmission electron microscopy, results of microstructure and phase characterization were correlated with diffusion phenomena. For the pure Ta barrier, Ta diffusion through the Cu cap layer to the sample surface is observed at T an =500 °C, and the transformation of initially grown metastable β-Ta into the equilibrium α-Ta phase occurs at T an =600 °C. In contrast, a fcc TaN layer remains stable at least up to T an =700 °C. In the case of the graded layer stacks, first signs of N diffusion out of the TaN film into the adjacent Ta layers are observed after annealing at T an =300 °C, and formation of hexagonal Ta 2 N starts at T an =500 °C. Whereas in the course of thermal treatments for the threefold graded Ta/TaN/Ta barrier all TaN reacts with Ta to form Ta 2 N, some fcc TaN remains in the twofold graded TaN/Ta barrier.

Aluminum oxide was deposited using atomic layer deposition on either a silicon oxide or a silicon nitride interface. Water vapor or ozone were used as oxidation precursors. The structural properties of these films were investigated by time-of-flight secondary-ion-mass-spectroscopy (ToF-SIMS), X-ray photoelectron spectroscopy (XPS) and elastic recoil detection (ERD). Special attention was given to contamination issues of the film and the interface, bonding conditions and temperature influence on diffusion. The results suggest that the silicon most likely diffused along grain boundaries of polycrystalline Al2O3. Carbon and hydrogen were located at the interface and furthermore hydrogen diffused out of the film to some extent due to anneal. Carbon content in the layer was reduced when using O3 as an oxidant. The formation of metallic aluminum clusters was not observed for any of the investigated process conditions.

Integration of materials with a high dielectric constant into storage or gate capacitor applications requires a detailed understanding of the crystallization behavior. The dependence of crystallinity on annealing temperature and time was studied for thin atomic-layer-deposited (ALD) Al2O3 films of varying thickness, using grazing-incidence X-ray diffraction. The correlation between dielectric constant and annealing condition was investigated and an increase in dielectric constant due to annealing was observed.

The high- k dielectric material (Ba,Sr)TiO 3 has been intensively investigated for possible applications in dynamic random access memory circuits. During the BST deposition process in O 2 ambient, typically at 650°C, the diffusion of oxygen through the bottom electrode into the poly Si plug must be prevented. Amorphous TaSiN films are excellent candidates as oxygen barrier layers. Ba 0.5 Sr 0.5 TiO 3 (BST) films with thickness of 100 nm were deposited on the electrode structure SiO 2 /TaSiN/Pt. The sol–gel method was used to grow the BST films. The barrier effect for oxygen diffusion is studied in TaSiN layers with thickness of 50 nm, which were deposited by a reactive sputter process. X-ray photoemission spectroscopy results confirm that this amorphous material is a suitable barrier against oxygen diffusion at 650°C. The BST films, deposited at 650°C and post-annealed at 650°C show a dielectric constant of 100 at 100 kHz and a dissipation factor of less than 5%.

The erosion plume resulting from an ablation of a tantalum target in vacuum with an excimer laser radiation (308 nm) was studied using the Langmuir probe technique. The spatial and temporal dependencies of the electron probe currents were obtained in real time. The electron temperature of different plume regions was determined from a series of I–U characteristics taken at different distances between the probe and the target. We determined that the plume electron temperature is non-uniform and has a maximum value in front of the plume.

The laser plasma plume expansion induced by UV nanosecond irradiation from metallic Nb and Ta targets has been studied using Langmuir probe time-of-flight measurements. The ion current shape was measured as a function of the laser radiation flux at various probe-to-target distances. The ion velocity distribution and the ion energy spectra have been determined by measuring the time of flight of ions reaching the Langmuir probe. A multi-mode velocity distribution of ions has been revealed. The dependence of the amplitudes of the plume energy components on the plume scatter time and on the laser radiation flux has been investigated. The experimental time-of-flight data have been compared with a Maxwell velocity distribution. The threshold values of the laser intensity were determined for different distribution modes in the ion energy spectrum.

An advanced CMOS scheme for the integration of a graded epitaxial Silicon Germanium (SiGe) layer is presented. SiGe is deposited into the source drain regions right after gate formation to create compressive strain in the transistor channel of the pMOSFETs and thus improve charge carrier mobility. The SiGe layer is exposed to subsequent process steps such as cleaning, implantation and annealing which cause erosion and dopant loss. This effect becomes more severe with increasing Ge content, which is wanted to increase stress in the channel. The negative effect of SiGe erosion on DC transistor performance is shown in this paper and how it can be reduced by optimized SiGe deposition utilizing a two layer stack with different Ge content. First a film with higher Ge concentration is deposited followed by a lower percent Ge film which is aimed to protect the SiGe film underneath. Electrical data for PMOS devices with 55 nm embedded SiGe with 20–30% Ge are presented and compared to the corresponding graded SiGe stack (25–30%, 50 nm with 5 nm thick 15% cap). Comparing Embedded Silicon Germanium (eSiGe) devices with 30 at% Ge, we see a 5% I DSAT improvement for the graded layer over the monolithic one.

Low temperature etching of Si with SF"6 has been studied, using a DECR system and a special Helicon type plasma source. In contrast to the current understanding of low temperature etching, we did not observe a ''freezing'' of the lateral etching reaction, but obtained isotropic etch profiles, even at temperatures below -120^o C. Anisotropic etch profiles are obtained by an addition of O"2. We therefore propose a sidewall passivation mechanism to explain the reduction of the lateral etching. Si etch rates of [email protected]/min at selectivities Si/SiO"2 well above 100/1, with anisotropic profile have been obtained.