A gas cell for in-situ measurements of Volatile Organic Compounds (VOCs) and their adsorption behaviour on different surfaces by means of X-ray Fluorescence (XRF) and X-ray Absorption Fine-Structure ...(XAFS) spectroscopy has been developed. The cell is especially designed to allow for the efficient excitation and detection of low-Z elements such as carbon, oxygen or nitrogen as main components of VOCs. Two measurement modes are available. In the surface mode, adsorption on a surface can be studied using XAFS by fluorescence detection under shallow angles of incidence. The transmission mode enables the simultaneous investigation of gaseous samples via XAFS in transmittance and fluorescence detection modes. Proof-of-principle experiments were performed at the PTB plane grating monochromator beamline for soft X-ray radiation at the synchrotron radiation facility BESSY II. The flexible design and high versatility of the cell are demonstrated with the investigation of ethanol (EtOH) as one of the most abundant VOCs. The comparison of Near-Edge X-ray Absorption Fine-Structure (NEXAFS) spectra under transmission and fluorescence detection in the gas phase with measurements of adsorbed molecules on a Si-wafer surface both at the C and O-K absorption edges proves the applicability of the cell for the monitoring of adsorption processes.
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•X-ray spectroscopy of gaseous samples•Specially in the spectral range of soft X-ray radiation (C, N, O)•Transmission and fluorescence simultaneously.•Sample cell for X-ray Fluorescence (XRF) and X-ray Absorption Fine-Structure (XAFS)•Grazing incidence excitation allows for quantitative XRF investigations•Investigations of Volatile Organic Compounds (VOCs) on exchangeable surfaces.•Proof-of-principle experiment shows adsorption of ethanol on Si wafer surface.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The preparation of aminated monolayers with a controlled density of functional groups on silica surfaces through a simple vapor deposition process employing different ratios of two suitable ...monoalkoxysilanes, (3-aminopropyl)diisopropylethoxysilane (APDIPES) and (3-cyanopropyl)dimethylmethoxysilane (CPDMMS), and advances in the reliable quantification of such tailored surfaces are presented here. The one-step codeposition process was carried out with binary silane mixtures, rendering possible the control over a wide range of densities in a single step. In particular, APDIPES constitutes the functional silane and CPDMMS the inert component. The procedure requires only small amounts of silanes, several ratios can be produced in a single batch, the deposition can be carried out within a few hours and a dry atmosphere can easily be employed, limiting self-condensation of the silanes. Characterization of the ratio of silanes actually bound to the surface can then be performed in a facile manner through contact angle measurements using the Cassie equation. The reliable estimation of the number of surface functional groups was approached with a dual-mode BODIPY-type fluorescence label, which allows quantification by fluorescence and XPS on one and the same sample. We found that fluorescence and XPS signals correlate over at least 1 order of magnitude, allowing for a direct linking of quantitative fluorescence analysis to XPS quantification. Employment of synchrotron-based methods (XPS; reference-free total reflection X-ray fluorescence, TXRF) made the traceable quantification of surface functional groups possible, providing an absolute reference for quantitative fluorescence measurements through a traceable measurement chain.
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IJS, KILJ, NUK, PNG, UL, UM
Bovine fibrinogen monolayers on thin gold films and glassy carbon substrate were investigated using grazing incidence X‐ray fluorescence (GIXRF) and spectroscopic ellipsometry (SE). The aim was to ...determine the amount of protein and to develop models and references for the SE measurement. Both methods were capable of measuring protein amount in the range of μg cm−2 with a sensitivity below 10%, which suggests the use of both techniques as complementary, combined methods. To do it with a high confidence, the lateral uniformity and the stability of the layers during transportation has to be investigated in more detail in the future.
Spectroscopic ellipsometry (SE) and X‐ray fluorescence (XRF) are used to measure protein monolayers on gold and amorphous carbon substrates. The amount of protein on the surface is quantified in terms of mass per unit area using de Feijter's method and a reference‐free approach for SE and XRF, respectively. A good agreement is found, pointing out the importance of the lateral homogeneity and temporal stability.
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This special edition contains the proceedings of ALTECH 2014 – Analytical Techniques for Precise Characterisation of Nanomaterials, Symposium H of the European Materials Research Society (E‐MRS) ...Spring Meeting 2014 that was held in Lille, France, from 26th–30th May. ALTECH is a series of conferences initiated in 1989. The conference was offered as a satellite of symposium of semiconductor conferences in Europe or, on occasion, in the U.S., with a strong focus on analytical techniques for microelectronics manufacturing and research. In 2012, the German metrology institute PTB joined the executive board of the ALTECH and proposing a broadening of the ALTECH scope towards the characterization of nanomaterials. While imec has ensured the organizational continuity, further European metrology institutes adhered to the organizational board which made ALTECH to an important European metrology event on nanomaterials characterisation.
Our conference covered recent and innovative developments in analytical techniques that can provide precise characterization of surfaces and materials, characterization of nanostructures and study of thin films with nanoscale and/or atomic resolution. In total, 167 contributions were presented, including 11 invited presentations, 87 contributed oral presentations and 69 poster presentations. The event also included significant contributions from the European Metrology Research Program projects 'Metrology for the manufacturing of thin films', 'Traceable characterization of nanostructured devices', 'Novel electronic devices based on control of strain at the nanoscale', and 'Chemical metrology tools for manufacture of advanced biomaterials in the medical device industry' including related tutorial sessions.
Nanomaterials have unique properties associated with their small dimensionality. Functional nanomaterials are rapidly finding wider use in modern technological products in many areas, for example, displays, energy conversion, energy storage, sensors and biosensors. The accurate characterization of nanoscale materials is essential for the development of such innovative products. Conversely, properly engineered nanomaterials are currently seen as one of the most promising tools for high resolution optical microscopy.
The objective of ALTECH was to highlight metrology capabilities for both the determination of the key structural and material property parameters in view of a better understanding of the related functional properties. One major focus was the application of these techniques to new and complex material systems with high potential of industrial impact, including nanoscale objects (nanowires, quantum dots), nanostructured thin films of organic, hybrid, or inorganic semiconductors, and functionalized surfaces. A special focus was given to complementary metrology in terms of using different analytical techniques with the aim of ensuring accuracy and traceability, i.e. the inclusion of a well‐described uncertainty budget. As many of these techniques depend on modelling to achieve reliable results, effective material analysis and computational analysis of materials and thin layers were also a key topic.
These proceedings contain a selection of 23 manuscripts published in pss (a) and pss (c). pss (c) is organized in three sections:
– Analysis of surfaces and materials
– Characterization of nanostructures
– Study of thin films.
We would like to thank all invited speakers, contributors and attendees for their high‐quality contributions and excellent discussions which made ALTECH a very successful meeting. We are grateful to the scientific committee and external colleagues who supported the symposium and the organisation of these proceedings as well as acted as session chairs and reviewers.
We thank the E‐MRS headquarter staff for their assistance in organising the symposium as well as Wiley‐VCH for helping with the publication of these proceedings. We also would like to acknowledge the sponsorship of several companies and institutions (NPL, Berlin Partner, Rigaku, Elexience, EXSA, INRIM, AXO Dresden, Sentech), as well as the support of the European Union through the European Metrology Research Programme (EMRP), projects IND07 ThinFilms and NEW01 TReND, IND54 Nanostrain, and IND56 Q‐AIMDS. The EMRP is jointly funded by the EMRP participating countries within EURAMET and the European Union.
Andreas Nutsch, PTB, Germany
Fernando Araujo de Castro, NPL, U.K.
Christoph Adelmann, Imec, Belgium
Blanka Detlefs, CEA‐Leti, France
Guest Editors
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The scaling down of critical dimensions for the manufacturing of nanoelectronics requires the continuous introduction of new materials. The results of the analysis of thin high-
k
films made from Al
...2
O
3
as reference samples were used at multiple laboratories to show the power and strength of complementary metrology,
e.g.
using various techniques, such as synchrotron radiation X-ray spectrometry, 'table top' grazing incidence X-ray spectrometry and X-ray reflectometry, and spectroscopic ellipsometry. The layer thicknesses and material parameters validated by several analytical techniques demonstrate the successes of the use of complementary metrology. The requirement for validation, assurance, and support using differing analytical methods is driving the integration of multiple methods into one tool. This paper proposes an integrated metrology approach for reliable characterization of structure and composition. For the analysis of surfaces and materials, light sources in different spectral ranges,
e.g.
X-rays or infrared light, are used for diffraction, scattering, or excitation of fluorescence. The use of appropriate detectors in the scattering or fluorescence geometry is indispensable. Highly precise metrology requires accurate positioning of the sample with respect to the sources and the detectors. The handling unit for samples and automation are the main contributors to the cost of the semiconductor metrology equipment. For this reason, the approach of integrating multiple analytical techniques has advantages with respect to cost aspects and handling steps. A design study of the 450 mm analytical platform was performed. This design study integrates seven complementary analytical methods into one metrology chamber. Five methods rely on X-ray characterization methods, such as Total Reflection X-Ray Fluorescence Analysis (TXRF), Grazing Incidence X-Ray Fluorescence Analysis (GIXRF/XRF), X-Ray Reflectometry (XRR), X-Ray Diffractometry (XRD), and Grazing Incidence Small Angle X-Ray Scattering (GISAXS). Furthermore, the two methods of spectroscopic ellipsometry and vacuum UV reflectometry using the spectral range of ultra-violet to infrared were supplemented. A novel 5-axis positioning system was designed and patented, enabling the integration of all analytical methods into one chamber under vacuum or atmospheric conditions.
The feasibility of integration of seven complementary analytical methods in one advanced metrology chamber for 450 mm wafers is demonstrated.
Currently, yield enhancement and APC (advanced process control) systems operate independently within the manufacturing process. Yield enhancement has several requirements such as the root cause ...analysis of yield loss, the reliability of defect density data, and the demand for a link between yield models and APC. For root cause studies chemical analysis uses different preparation techniques to describe the nature and location of contamination or defect densities, e.g. copper bulk contamination or wafer edge effects. The reliability of defect density data and the matching of defect inspection tools improve by the reduction of noise. In combination with a process model this is the prerequisite to set up a random defect-based yield scenario which describes single processes. The combination of this scenario with methods for data acquisition and tracking from APC enhances the prediction of yield.
Selective in-filling growth by chemical beam epitaxy (CBE) is ideally suited for the monolithic integration of InP-based laser diodes and photonic devices. The growth was carried out on exactly ...oriented (100) n-InP substrates as well as on 2° off toward next 110 oriented substrates. The preparation of the substrates and the growth parameters,
e.g.
growth rate, strongly influences the shape and optical properties of embedded (GaIn)(AsP) laser diodes shown by scanning electron microscopy (SEM) and spatially resolved cathodoluminescence (CL) measurements. By reducing the growth rate from 1.3 µm/h to 0.4 µm/h at a high V/III
B
E
P
ratio of 18 during the growth of the InP buffer flat layers are grown within narrow grooves. Separate confinement heterostructure (SCH) multi quantum well (MQW) laser diodes (λ=1.55 µm) with cleaved mirrors selectively in-filled in 3 µm wide grooves show a device performance comparable to conventional `state of the art' quaternary laser diodes;
e.g.
lasers with 6 QW show threshold currents of 16 mA and light output of several mW in CW operation. By butt joining we integrated quaternary ridge waveguide (RW) laser diodes and waveguides.
Cavity 'ringdown' spectroscopy is besides ion mobility spectroscopy another technique for the online detection of volatile compounds in air. Based on absorption spectroscopy, cavity 'ringdown' ...spectroscopy (CRDS) works by attuning light from a laser to a wavelength in the infrared spectrum at which a certain contaminant adsorption peak occurs. The concentration is calculated from the time it takes for the light to fade or 'ringdown' within an adsorption cell (cavity) which is filled with the gas to be analyzed. A test setup for generation of airflows contaminated with acids substances of H-X type was build and tested successfully. The setup was used to compare a cavity 'ringdown' spectroscopy with impinger sampling in combination ion chromatography. The developed methods can be used for the evaluation of HF-levels in the clean room air. CDRS can be used to monitor HF-levels under dynamic conditions of local sources continuously.
A gas cell for in-situ measurements of Volatile Organic Compounds (VOCs) and their adsorption behavior on different surfaces by means of X-Ray Fluorescence (XRF) and X-ray Absorption Fine-Structure ...(XAFS) spectroscopy has been developed. The cell is especially designed to allow for the efficient excitation and detection of low-Z elements such as carbon, oxygen or nitrogen as main components of VOCs. Two measurement modes are available. In the surface mode, adsorption on a surface can be studied using XAFS by fluorescence detection under shallow angles of incidence. The transmission mode enables the simultaneous investigation of gaseous samples via XAFS in transmittance and fluorescence detection modes. Proof-of-principle experiments were performed at the PTB plane grating monochromator beamline for soft x-ray radiation at the synchrotron radiation facility BESSY II. The flexible design and high versatility of the cell are demonstrated with the investigation of ethanol (EtOH) as one of the most abundant VOCs. The comparison of Near-Edge X-ray Absorption Fine-Structure (NEXAFS) spectra under transmission and fluorescence detection in the gas phase with measurements of adsorbed molecules on a Si-wafer surface both at the C and O-K absorption edges proves the applicability of the cell for the monitoring of adsorption processes.
In this paper we address the problem of revealing copper contamination induced in the device region by the final part of the process. A method to reveal the effects of copper contamination is ...identified based on the recovery of MOS capacitors from deep depletion. In the presence of copper contamination carrier generation is dominated by surface generation, which is not surprising because copper is known to be prone to surface segregation. Copper segregation at the wafer surface was also confirmed by TOF-SIMS measurements. The measurements of surface generation velocity are non-destructive and the required structures can be easily integrated in device wafers. However, a recovery of the copper-related surface generation velocity with the time spent after the thermal treatment was observed. For this reason, it is important that the measurements are carried out in a short time after the thermal treatment responsible for copper segregation at the wafer surface.
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