Nondestructive and In-Situ Characterization
Friday, April 14, 2000 8:30 AM in Room San Diego
F2-1 In Situ Studies of Diffusion and Crystal Growth in Plasma Depsoited Thin ITO Films
H. Wulff, M. Quaas, H.J. Steffen, R. Hippler (University of Greifswald, Germany)
Tin-doped indium oxide (ITO) films were deposited on unheated Si(100) substrates by means of DC-planar magnetron sputtering. A metallic In/Sn (90/10) target and oxygen as reactive gas were used. The flow of the reactive gas oxygen was varied between 0 and 2 sccm and bias voltages were used between 0 and -100 V. With increasing oxygen flow film structure and composition change from crystalline metallic In/Sn to amorphous ITO. The diffusion of oxygen into metallic films and the amorphous-to-crystalline-transformation of ITO were studied in this system using in situ grazing incidence x-ray diffractometry (GIXRD), grazing incidence x-ray reflectometry (GIXR), AFM and XPS. In situ measurements of GIXRD were made during annealing in vacuum (10@super -6@ mbar) at temperatures that ranged between 100@super o@C and 300@super o@C. The studies show that two processes determine the ITO crystal growth, the diffusion of oxygen into the metallic film and a fast crystallization of amorphous ITO. The kinetic parameters diffusion constant, activation energy as well as reaction order and activation energy of crystal growth process were extracted from the x-ray integral intensities. An analytical model was developed for the investigation of the diffusion processes. From this model the effective diffusion coefficient D was determined. It can be shown that the diffusion coefficient D depends on the plasma parameters. Crystallization occurs via classical nucleation and growth mode parameter that is consistent with three dimensional transformation geometry.
F2-2 A Structural Analysis PVD-grown TiAlN/Mo Multilayers
C.J. Tavares (Universidade do Minho, Portugal); L. Rebouta (Universidade do Minho, Portugal); E. Alves (ITN, Portugal)
The quest for a reliable and effective coating which will protect and enhance the mechanical properties of the underlying substrate, and the coating itself, is a scientific area that recently has witnessed many important industrial developments. Bearing this in mind, TiAlN/Mo multilayers have been designed to fulfill these purposes. They have been deposited with dc magnetron sputtering on high-speed steel substrates, with varying modulation periods. Experimental X-ray diffraction (XRD) and computational refinement of the latter patterns has undergone to achieve the basics to elucidate their structural properties. The ultramicrohardness, residual stress and adhesion to the substrates have also been accessed.
F2-3 X-ray Study on Residual Stress and Deformation Behavior of Composite Plating
H.M. Masuda, S.T. Takago, Y.H. Hirose (Kanazawa University, Japan)
The composite plating method is used to develop the surface strength of the material. In this study, prepared composite plating is composed of the Ni-Co-P alloy and the silicon nitride made by the electrolysis plating method. Ni-Co-P/?-Si3N4 composite plating is put to practical use on the wear and heat resistance compared with a past as Cr plating etc. It has been put to practical use by the piston ring, which is parts of the excellent gasoline engine and the liners. An X-ray stress measurement method as nondestructive and non-contact. It is possible to exercises the elucidation of the stress state at surface layer in a thin film and the composite material. There is a liner relation between diffraction angle 2? and sin2?. We can measure the residual stress with each other from the relation. It is forecast to become complex the stress state by the Dual phase material the material which contains ?-Si3N4, and generating the microscopic stress by the influence of the interaction. The X-ray stress measurement method was used to Ni-Co-P/??-Si3N4 composite plating in this study, and then, it caused for the deformation behavior of the matrix and the influence of film thickness on residual stress was discussed.
F2-4 Thickness Dependent Effective Thermal Expansion Properties of Ultra-thin Polymer Films
B.C. Chung, H.K. Kim, F.G. Shi (University of California, Irvine); B. Zhao, M. Brongo (Conexant Systems, Inc)
Investigating the thermal expansion properties of thin films is of crucial importance, since a mismatch in thermal expansion coefficients between the film and the substrate is a major source of stress on the thin film. The electronic industry has known that such stresses from thermal expansion coefficient mismatches lead to interlayer delamination, surface roughening and cracking. Although research has been performed on the thermal expansion of thin films, there is little information on the thickness dependent thermal expansion of films, especially that of ultra-thin films. In the present work, we investigated the thickness-direction thermal expansion properties for several ultra-thin advanced low-k crystalline polymer films in the thickness range of 48 to 1140 nm. Each sample was pre-heated to remove residual moisture and the thickness change was studied over the range of 25 to 305 (C, which is prior to the melting temperature. Temperature dependent thickness measurements were made by a thin-film measurement system (Filmetrics F20) which determines the thickness by measuring the reflectance spectrum and comparing it with a series of calculated reflectance spectra. From this data, the thickness dependent out-of-plane thermal expansion coefficients (TEC) for the various thickness samples and the temperature dependent TECs were analyzed. Analysis results showed that the TECs were strongly thickness dependent and was mildly temperature dependent. Glancing angle x-ray diffraction (XRD) and fourier transform infrared spectroscopy (FTIR) were performed for a definite identification of the chemical and an evaluation of their phase information.
F2-5 Optical Emission Spectroscopy of a PCVD Process Used for the Deposition of TiN on Cemented Carbides
S. Peter (University of Chemnitz, Germany); R. Tabersky, U. König (Widia-Valenite, Essen, Germany); F. Richter (Technical University of Chemnitz, Germany)
In thermal CVD only few process parameters are accessable during a coating run. Thus the knowledge on the true reaction mechanism of the deposition is rather scarce. It is almost unknown how the different molecule fragments do influence the film growth and the resulting coating properties. In CVD processes enhanced by a plasma excitation of the gaseous species the analysis of the superposed optical emission spectra enables the direct observation of the reactive particles in the close vicinity of the growing film. Thus the in-situ OES analysis can give new insights into the deposition process, especially, if it is combined with methods for the characterization of the plasma process like Langmuir probe measurements, mass spectroscopy or laser-induced fluorescence. In this contribution we report on a new OES study of the PCVD process of the deposition of titanium nitride. From the results we expect a better understanding of the plasma processes used in the coating production of Widia/Valenite. The in-situ OES measurements were made with successively modified process parameters . Thus the most process specific lines of the large spectroscopical manifold were selected. Based on these results thick TiN coatings were deposited monitored by OES. The determination of the coating properties and its relations to the OES signals is in progress. First results will be presented.
F2-7 Classical and Acousto-optical Emission Spectroscopy of DC and Pulsed High Current Arc processes
J. Vetter (Metaplas Ionon GmbH, Germany); T. Wallendorf (IfU GmbH Floeha, Germany); T. Witke, P. Siemroth (Fraunhofer Institute for Material and Beam Technology Dresden, Germany)
Currently, vacuum arc processes are widely used to deposit thin films running in a broad spectrum of discharge parameters (e. g. arc currents between 50 and 5000 A) and pressures of reactive gases. It is well known that arc discharges generate highly ionized metal plasmas. The variation of the plasma state can excellently be studied by Optical Emission Spectroscopy. Until now, the DC arc is mostly used in industrial applications but there is a growing number of devices with pulsed high current arc discharges getting to industrial relevance. The present paper shows how arc discharge conditions may influence the ionization state of the generated plasma. A new development, the Acousto-optical Emission Spectroscopy (AOS) is described in the paper. It combines high temporal resolution (below microsecond) for preselected emission lines with high optical sensitivity. The paper contains a comparative discussion of the AOS device and a conventional grating spectrometer. Plasma pulses produced by HCA (High Current Arc) discharges were studied with microsecond resolution. Results of the temporal behavior of the main species will be present.
F2-8 Reduction of Si-OH Groups in Plasma-Deposited Silicon-Oxide Films at Low Substrate Temperatures
Y. Inoue, H. Sugimura, O. Takai (Nagoya University, Japan)
Recently plasma-enhanced chemical vapor deposition (PECVD) using organosilicon compounds has been extensively studied, because PECVD can lower a substrate temperature to deposit silicon-oxide films on polymer materials which have generally poor heat resistance. However, the deposition of silicon-oxide films at low temperatures leads to remains of Si-OH groups, which may degrade mechanical and optical properties of the films. In this study, we have performed monitoring of chemical bonding states on the growing film surfaces by infrared reflection absorption spectroscopy (IR-RAS) to understand the origin of the groups as well as the way to reduce them. @paragraph@We used a remote-type rf-PECVD system. After evacuation below 10@super -4@ Pa, a reactant organosilicon gas and an oxygen gas were introduced into a deposition chamber. Total pressure and rf power were kept at 10 Pa and 75 W. In-situ observation of film surfaces was carried out by a Fourier-transform infrared spectrometer. @paragraph@Vibrational absorption bands due to Si-O-Si networks and Si-OH bondings were strongly observed. In addition, absorption bands due to -COOH groups were also detected. The intensities of the absorption bands due to Si-OH increased almost linearly with deposition time t. On the other hand, the peak shape for O-H absorption depended on t. It means that at least two kinds of -OH bonding states exist in the films and that their compositions change with t.
F2-9 Measurement of Out-plane Thermal Expansion of Thin Films
H.H. Zhu, G.G. Li, D.A. Harrison, I. Bloomer (n&k Technology, Inc.)
The differences in the coefficient of thermal expansion (CTE) amongst thin film layers in planar semiconductor devices can adversely affect the performance of integrated circuits. These mismatches in CTEs can build up stress and ultimately result in delamination and/or other undesirable consequences. Therefore, a quick, accurate, and reproducible method of characterizing CTE is required to ensure the quality of such devices. @paragraph@ In this paper, we present the results of recent measurements of out-plane CTE on polymer, porous SiO@sub 2@ and thermal SiO@sub 2@ thin films deposited on Si substrates @footnote 1@. The results were obtained using a spectrophotometric technique that incorporates the Forouhi-Bloomer dispersion equations to simultaneously and non-destructively determine the thickness and optical constants (n and k) of the layers @footnote 2@. Significant and material dependent changes in the refractive indices of the materials were detected during thermal expansion. @paragraph@ The results of this work are compared with measurements from other optical techniques, which assuming constant values in the refractive index of the materials. It is demonstrated that significant errors and inaccurate results may be encountered when operating under such assumptions. @FootnoteText@ @footnote 1@ The authors would like to thank and acknowledge Brad Sun of Intel Corporation for establishing this work and providing samples. @footnote 2@ A.R. Forouhi and I. Bloomer; Phys. Rev. B34, 7018 (1986); ibid. 38, 1865 (1988).
F2-10 In-situ Hard Coatings Strain Measurement Using a Commercial Strain-Gage Device
M. Cremona, L. Moraes Gazola, L.C. Scavarda do Carmo, J. Tupiassu P. de Castro (Pontificia Universidade Catolica do Rio de Janeiro, PUC-Rio, Brazil); C.A. Achete (Universidade Federal do Rio de Janeiro, UFRJ, Brazil)
For many surface coating applications it is fundamental to accurately monitor and control the film's physical properties for a particular selected purpose. Particularly important are the thermal and/or residual stresses, which occur in the process of hard coating deposition. These stresses can affect the optical, electrical, magnetic and mechanical properties of the film and, consequently, the need to measure and control the stress it is vital for the success of the final device. The development of in-situ analyses not only provides the possibility of a feedback control during deposition, but also assists in a more efficient evaluation of the best conditions to achieve particular properties. @paragraph@ In this work we present a novel technique which can be utilized to measure in-situ the induced substrate strain caused by the stress working in the depositing film. The technique, based in the employment of a commercial strain-gage, was used during the deposition of ultr! a-ha rd silicon carbide (SiC) films by RF Magnetron sputtering, onto thin (95µm) stainless steel substrates. The direct measurement of the electrical resistance of the strain-gage by using a 7@super 1/2@ digits high-resolution multimeter, provides the strain values used to found the stress present in the film/substrate interface. Using a value of 480 GPa for the Young modulus of the SiC film @footnote 1@, preliminary results furnish a value of the stress @sigma@ of about 0.8 GPa which is in good agreement with other ex-situ measurements performed on the same material @footnote 2@. Furthermore, it was found that the sensibility of this technique is about 1x10@super -5@. The research is under way to improve the accuracy and study the possibility to develop a more compact device. @paragraph@ This work is supported by PADCT III - CNPq , and FINEP. @FootnoteText@ @footnote 1@ M. Ohring, The Material Science of Thin Films, Academic Press, San Diego, USA, 1992. @footnote 2@ Deposition ! and Characterization of Ultra-Hard Silicon Carbide Coatings by RF Magnetron Sputtering, A Costa, R. Carius , C. Achete and S. Camargo, ICMCTF2000 - submitted
F2-11 Solute Impregnation: A New Technique to Characterize the Porosity of Thin Films
C.M. Lopatin, V.B. Pizziconi, T.L. Alford (Arizona State University)
A new technique has been developed to characterize the porosity of thin films. Designated “Solute Impregnation”, the method consists of immersing the film in a solution containing a tracer solute species, allowing the tracer to penetrate into the film via any pores that are open to the surface. The tracer adheres to the inner surface of the pores, and its presence, which can be determined through a variety of methods, provides information regarding the nature of the porosity. In the present work the method was applied to the study of sol-gel derived, sub-micron thin films of the bio-ceramic hydroxyapatite. Barium atoms were used as the tracer species, and Rutherford backscattering spectrometry was used to obtain the concentration depth profile of the barium, thus also providing a depth profile of the porosity. It was found that the films had an open pore structure throughout the film thickness. It was also found that the degree of porosity decreased when the films were densified using ion-implantation, confirming the validity of the technique. It was also found that some degree of depth asymmetry was introduced with implantation, demonstrating that solute impregnation can be used to probe subtle effects that are difficult to observe with other methods.