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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 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.

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.

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.

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.

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 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.

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.