H. Ruelke

GlobalFoundries Inc., Schenectady, New York, United States

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Publications (22)11.69 Total impact

  • C. Kubasch · T. Olawumi · H. Ruelke · U. Mayer · J. W. Bartha

    No preview · Article · Jan 2015
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    C Kubasch · H Ruelke · U Mayer · J W Bartha
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    ABSTRACT: At different moisture levels the leakage current and the disruptive strength of SiCOH, a nonporous low-κ dielectric, has been investigated. If water is in the dielectric film, the current density increased of about 6 orders of magnitude due to the ionization of water molecules in the applied electric field. Furthermore, at a constant electric field the delay time until the highest current value is reached depends on the water concentration and the silanol amount in the dielectric film. The delay time can vary between 1 minute in an untreated sample and 39 minutes in a thinner and plasma treated sample. In addition, the disruptive strength in the dry state and in the water saturated state at 80% relative humidity remains constant at about 10 MV/cm.
    Full-text · Article · Nov 2014
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    C Kubasch · T Olawumi · H Ruelke · U Mayer · J W Bartha
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    ABSTRACT: A porous ultra low-κ dielectric (pULK) and a dense SiCOH dielectric were investigated before and after a plasma treatment with argon in terms of the change in the bonding types, the relative permittivity and the water uptake. Fourier transform infrared (FTIR) spectroscopy revealed a change in the bonding types of the dielectrics in general and a significant increase in the hydroxyl band especially. The high hydroxyl amount leads to an increase in the relative permittivity of these dielectrics by up to 6.25% for SiCOH and up to 12.5% for the pULK material. Furthermore, if water diffuses into the dielectric films from the environment, the moisture uptake is up to 2.7 times higher in saturation at 80% relative humidity in comparison to the untreated samples. Due to the plasma damaged upper layer of the materials, the diffusion process of water into the bulk dielectrics is significant reduced. Overall, it has been found that the pULK material is more vulnerable to the used plasma treatment in comparison to the dense SiCOH film.
    Full-text · Article · Oct 2014
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    Full-text · Dataset · Aug 2013
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    T. Breuer · U. Kerst · C. Boit · E. Langer · H. Ruelke · A. Fissel
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    ABSTRACT: The electrical degradation of ultra low-k SiCOH dielectric before breakdown is investigated. A new technique to obtain information before breakdown has been developed to define stress conditions and observe degradation patterns before total destruction occurs. Electrical measurements and physical inspection in specifically designed test structures have been made to focus on intrinsic properties. A typical leakage current characteristic, voiding and tantalum transport have been observed. These observations have been interpreted by quantitatively adapting physical effects. This investigation provides a model that describes the observed phenomena in a qualitatively manner.
    Full-text · Article · Dec 2012 · Journal of Applied Physics
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    ABSTRACT: This experimental study presents a comparison of differently tensile stressed silicon nitride (SiN) layers and their response to irradiation in a vacuum ultraviolet (VUV) curing system. Therefore, three types of silicon nitride with initial stress levels of 450 MPa, 700 MPa and 980 MPa were deposited by plasma enhanced chemical vapor deposition (PECVD). In contrast to industrial standard VUV curing with broadband lamps ≥ 220 nm radiation wavelengths, we analyzed the effects of curing with single wavelengths at 172 nm and 222 nm. The samples were characterized by Fourier Transform Infrared Spectroscopy, ellipsometry, and wafer bow measurement. It could be shown that high energy photons are able to dehydrogenize SiN films more than lower energetic photons compared with lower Si-N-Si crosslinking effects. Furthermore, we could show that a dual combined 172 nm and 222 nm VUV curing procedure can produce films with very low hydrogen concentration and high percentage of structural units consisting of Si-N-Si bonds. In conclusion of this study, an up to +900 MPa stress increasing process could be established.
    No preview · Article · Jan 2012 · MRS Online Proceeding Library
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    ABSTRACT: A dense plasma enhanced chemical vapor deposition (PECVD) SiCOH film and a porous ultralow-κ (pULK) film have been investigated by means of the Fourier transform infrared spectroscopy. Structural differences between both materials have been found in particular in the amount of silanol groups and in the location and shape of the Si-O-Si stretching vibration band. Furthermore, moisturized samples of these materials have been investigated in situ during outgassing in rough vacuum. It has been observed that the pULK film contains only about 25% of the water amount found in the dense SiCOH film in saturation at 80% relative humidity and room temperature. A comparison of the water-related species in the investigated dielectric films with a liquid water spectrum identified hydrogen-bonded water-silanol groups in both materials and hydrogen-bonded water-water groups in the pULK film. During the outgassing process, no indication of shrinking or other structural changes were found, except for a shift in the silanol-associated vibration band to slightly higher wavenumbers. The achieved results are in good agreement to previous electrical characterization of both dielectric films.
    No preview · Article · Oct 2011 · IEEE Transactions on Electron Devices
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    ABSTRACT: Reactive ion etch processes for modern interlevel dielectrics become more and more complex, especially for further scaling of interconnect dimensions. The materials will be damaged within such processes with the result of an increase in their dielectric constants. The capability of selected additives to minimize the low-k sidewall damage during reactive ion etching (RIE) of SiCOH materials in fluorocarbon plasmas was shown in different works in the past. Most of the investigated additive gases alter the fluorine to carbon ratio as well as the dissociation of the parent gas inside the etch plasma. The result is a changed etch rate, a modified polymerization behavior and other characteristics of the process induced SiCOH damage. Heavy inert ions like argon will be accelerated to the sample surface in the cathode dark space and enhance therewith the sputter yield on the SiCOH network [1]. In this paper the additives Ar, O2, C4F8, H2, N2 and CO were added to a conventional CF4 etch plasma. We try to provoke different changes in the plasma conditions and therewith in the process results. Contact angle measurements, spectroscopic ellipsometry, Hg-probe analysis, FTIR measurements and SEM cross-sections were used to overview the additive induced modifications. To understand the influences of the additives gases more exactly, changes in the physical and chemical plasma behavior must be analyzed. Therefore quadrupole mass spectrometry (QMS) and quantum cascade laser absorption spectroscopy (QCLAS) were used.
    No preview · Article · May 2011 · Microelectronic Engineering
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    ABSTRACT: The influence of moisture on the electrical properties of PECVD SiCOH and a PECVD porous ultralow- κ (pULK) material has been investigated in comparison with a thermal oxide and a PECVD oxide. Capacitance-time ( C - t ) measurements are performed on metal-insulator-metal structures during exposure to different humidity conditions (0% to 80% RH) to determine the effect on the relative permittivity. The results show a big difference in the amounts of moisture absorbance of the investigated materials. While the PECVD oxide and the thermal oxide show no effect on exposure to a humid atmosphere, the increase in the permittivity of SiCOH due to moisture uptake is 7%, and surprisingly, the change in the permittivity of the porous dielectric material is 1.75%. Within these experiments, the diffusion process of moisture into the dielectric materials could be observed in situ , and a diffusion model is created to extract diffusion constants and a value for the saturation concentration. Furthermore, the flatband voltage shift of SiCOH and the pULK material in metal-insulator-semiconductor structures at different ambient humidity levels has been studied. The findings suggest that moisture uptake causes a positive charge inside the dielectric materials, which is responsible for the observed flatband voltage shift.
    No preview · Article · Sep 2010 · IEEE Transactions on Electron Devices
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    ABSTRACT: The focus of this paper is the impact of CF4 based plasma etch processes with the additives argon and C4F8 on material properties and geometrical parameters of etched trenches using dense and porous SiCOH. Argon and C4F8 were added to change the radical to ion composition and to shift the carbon to fluorine ratio, respectively. With several techniques, FTIR, spectral ellipsometry and contact angle measurements, modifications in the structure of the materials and their surface conditions were analyzed. To understand the influences of the additives on the plasma conditions, optical emission spectroscopy (OES) and quadrupole mass spectrometry (QMS) were used to estimate the composition of the plasma insitu.For the additive argon, a slightly enhanced etch rate and an increased refractive index due to serious plasma damage for porous SiCOH was observed. At higher Ar flow rates peaks of Si2O4Hx clusters in the QMS spectra and increased CO and O lines, measured with OES, indicate a higher sputter yield on the SiCOH network. SEM cross-sections show, that argon has no effect on the sidewall geometry of etched trenches. A higher CH/CN line in the OES spectra indicates an enhanced sputter effect of the SiCN films in via bottoms.For C4F8 addition results of spectral ellipsometry show a decreased etch rate and refractive index. Using FTIR the formation of a polymer film on the surface was observed. Higher C2 lines in the OES spectra are indications of enhanced polymerization efficiency. Finally, the addition of C4F8 decreases the etch rate in the trench sidewalls and therewith assumedly the sidewall damage.
    No preview · Article · Mar 2010 · Microelectronic Engineering
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    ABSTRACT: The focus of this paper is the improvement of etch processes for SiCOH dielectrics in CF4 plasmas with respect to the sidewall damage. Three different additives, Ar, O2 and C4F8, were admixed to the parent gas in different concentrations to provoke a change of the etch process. Argon was added to enhance the sputter effect on the SiO 4/2 matrix of the SiCOH. Using the additive O2, a serious damage of the SiCOH in combination with a CH3 extraction, an enhanced hydrophilic behavior and a surface densification was aspired. Finally the C4F8 was used to enhance the polymerization efficiency of the etch process. The real occurrence of the theoretical predicted mechanism was analyzed using different bulk and surface sensitive measurement methods, e.g. contact angle measurements, spectral ellipsometry, Hg-probe investigation and FTIR analysis. A slight reduction of the sidewall damage with C 4F8 addition and a small increase of this value using argon were measured using SEM cross sections. The plasma dissociation of the process gas and the formation of SiFx and COx compounds as reaction products were clear influenced by the additives, measured with quadrupole mass spectrometry (QMS). Measurements with the quantum cascade laser absorption spectroscopy (QCLAS) show a surprising saturation effect for SiF 4 in the reaction chamber. The maximum SiF4 concentration was 1.5·1013 molecules/cm3. It seems that higher SiF4 concentrations are not possible, when SiCOH will be etched. Finally a new evaluation method on the basis of the correlation coefficient was applied to find dependencies between changes in the surface energy and dielectric constant and the results of the optical emission spectroscopy (OES). Therewith it was possible to identify species in the plasma, which promote and hamper the process induced rise of the dielectric constant and the surface energy. A promoting behavior was found for fluorine and different oxidizing species. Compounds of carbon, nitrogen and silicon as well as argon hamper the process induced material degradation.
    No preview · Article · Jan 2010
  • T. Breuer · U. Kerst · C. Boit · E. Langer · H. Ruelke
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    ABSTRACT: This paper presents a basic investigation of Ultra Low K (ULK) SiCOH dielectrics degradation before breakdown. For the first time very early stages of degradation before breakdown have been revealed and a theory of the basic process of ULK alteration under electrical stress has been proposed. Tip electrode test structures have been specifically designed for this investigation in order to determine the location of degradation and breakdown. A stepwise increased voltage stress test with a meticulously observed current in fA range was developed and successfully applied.
    No preview · Article · Jan 2010
  • T. Breuer · U. Kerst · C. Boit · E. Langer · H. Ruelke
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    ABSTRACT: The degradation of Ultra Low K (ULK) SiCOH dielectrics before breakdown is investigated. For the first time very early stages of degradation before breakdown have been revealed and a model of the basic process of ULK alteration process under electrical stress is proposed. Two different degradation patterns were found. Tip electrode test structures have been specifically designed for this investigation in order to determine the location of degradation and breakdown. A stepwise increased voltage stress test with a meticulously observed current in the fA range was developed and successfully applied.
    No preview · Article · Jan 2010
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    ABSTRACT: The focus of this paper is to find correlations between the sidewall profiles as well as etch rates of SiCOH based low dielectric constant (low-k) films in fluorocarbon based plasma etch processes and specific plasma parameters, which were measured using optical emission spectroscopy (OES) and quadrupole mass spectrometry (QMS) as in situ diagnostics. SEM cross-sections were prepared to investigate the trench profiles after the etch processes. We found, that the change between CHF3 and CF4 base chemistry has an impact on the etch rate. In the SEM cross-section no distinctive impact on the sidewall profiles becomes visible. In situ measurements show a higher concentration of H ions and the presence of HF in the etch plasma using CHF 3 as base chemistry. With the introduction of argon, no distinctive impact on the sidewall profiles was observed in SEM cross-sections. But argon enhances significantly the concentration of CH and CN groups in the plasma. The additive C4F8 is a promising candidate to alter the sidewall profiles and the etch rate. SEM cross-sections show a minor reduced material removal at the trench sidewalls using C4F8 as additive. C4F8 has a smaller influence on the concentration of CH and CN groups than argon but it decreases significantly the concentration of C2 bands (swan bands). This indicates, that the C2 band concentration is a measure for the polymerization efficiency of the etch process. Finally, no differences in the chemical etch mechanism between dense and porous SiCOH films are observed as result of the in situ measurements. The porous films have pronounced higher etch rates than those of dense SiCOH and a weaker mechanical strength, which makes the etch process more difficult.
    No preview · Article · Jan 2009
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    ABSTRACT: An optimized 4-way stress integration on partially-depleted SOI (PD-SOI) CMOS is presented. An embedded-SiGe process and a compressive-stressed liner film are used to induce compressive strain in the PMOS (PMOS "stressors"). A stress memorization process and a tensile-stressed liner film are used to induce tensile strain in the NMOS (NMOS "stressors"). With optimization, the different stress techniques are highly compatible and additive to each other, improving PMOS and NMOS saturation drive current by 53% and 32%, respectively. This improvement results in 40% higher product speed. To demonstrate the extendibility for future transistor nodes the stress improvements were increased further resulting in record PMOS performance of IDSAT=860muA/mum at 200nA IOFF (self-heating corrected) and 1V. The stress techniques are proven in AMD's 90nm manufacturing processes, and have been scaled for use in 65nm manufacturing
    Full-text · Conference Paper · Jan 2006
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    ABSTRACT: A high performance 65 nm SOI CMOS technology is presented. Dual stress liner (DSL), embedded SiGe, and stress memorization techniques are utilized to enhance transistor speed. Advanced-low-K BEOL for this technology features 10 wiring levels with a novel K=2.75 film in selected levels. This film is a SiCOH-based dielectric optimized for stress to enable integration for enhanced performance. The resulting technology delivers pFET and nFET AC switching on-current of 735 muA/mum and 1259 muA/mum respectively, at an off-current of 200 nA/um (V<sub>dd</sub>=1.0 V), and 6% reduction in interconnect delay. Process yield is demonstrated on a SRAM cell with size of 0.65 mum<sub>2</sub>
    Full-text · Conference Paper · Jan 2006
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    ABSTRACT: For the first time, tensile and compressively stressed nitride contact liners have been simultaneously incorporated into a high performance CMOS flow. This dual stress liner (DSL) approach results in NFET/PFET effective drive current enhancement of 15%/32% and saturated drive current enhancement of 11%/20%. Significant hole mobility enhancement of 60% is achieved without using SiGe. Inverter ring oscillator delay is reduced by 24% with DSL. Overall yield for the DSL process is comparable to that of a similar technology without DSL. Single and multi-core SOI microprocessors are being manufactured using the DSL process in multiple, high-volume fabrication facilities.
    No preview · Conference Paper · Jan 2005
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    ABSTRACT: Partially depleted (PD) SOI technologies are mature for production of high speed, low power microprocessors. The paper highlights several challenges found during the course of development of a PD 90nm SOI technology. The technology features highly advanced transistors using strained Si and a gate length of sub 45nm with a nine layer low k hackend. By optimizing the strained Si process and overall processing we have achieved yield equal than conventional technologies but with higher performance. The technology was developed for the 64bit Opteron™ and Athlon™ 64 microprocessors.
    No preview · Article · Jan 2005
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    ABSTRACT: Partial depleted (PD) SOI technologies have reached maturity for production of high speed, low power microprocessors. The paper will highlight several challenges found during the course of development for bringing 40nm gate length (LGATE) PD SOI transistors into volume manufacturing for high-speed microprocessors. The key innovations developed for this transistor in order to overcome classical gate oxide and LGATE scaling is an unique differential triple spacer structure, stressed overlayer films inducing strain in the Silicon ...
    No preview · Article · Dec 2004 · Materials Science and Engineering B
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    ABSTRACT: Partial depleted (PD) SOI technologies have reached maturity for production of high speed, low power microprocessors. The paper will highlight several challenges found during the course of development for bringing 40nm gate length (L<sub>GATE</sub>) PD SOI transistors into volume manufacturing for high-speed microprocessors. The key innovations developed for this transistor in order to overcome classical gate oxide and LGATE scaling are an unique differential triple spacer structure, stressed overlayer films inducing strain in the Silicon channel and optimized junctions. This transistor structure yields an outstanding ring oscillator speed with an unloaded inverter delay of 5.5ps. The found improvements are highly manufacturable and scaleable for future device technologies like FD SOI.
    No preview · Conference Paper · Feb 2004