井上 尚三

This paper describes fabrication and characterization of MEMS hermetic package with lead-free solder film line heated by using exothermic Al/Ni multilayer structure. The Al/Ni structure deposited by DC magnetron sputtering shows self-propagating exothermic reaction. By applying a spark, the reactive structure generates heat enough to melt solder film. The heat of reaction depended on Al/Ni bilayer thickness and the total film thickness. We used the Al/Ni structure as a local heat source for MEMS soldering packages. The solder film-bonded silicon elements using the local heating were fabricated without other external heat sources. The bond strength examined by blister test was evaluated on the basis of weibull statistics.

This paper describes a simple evaluation method for in-plane Poisson's ratio of thin film materials. We designed an on-chip bending test chip that generates bending of film specimen via torsion bars, when applying normal load to loading levers. Using micro machining technologies, the test chip has been fabricated from SOI wafer. Average value of in-plane Poisson's ratio was 0.063, which deviates only 2% from the ideal value of single crystal Si. Therefore, this technique is useful for Poisson's ratio evaluation of thin film materials.

This paper describes an experimental analysis of surface stress distribution on single crystal silicon (SCS) microstructures using laser Raman spectroscope. A handmade tensile tester was employed to apply a uniaxial tensile stress to SCS specimen with a 270 nm-height and 4 μm-square SCS boss in the gauge section. In room temperature, Raman spectroscope measured surface stress, applied by the tensile tester, around the boss. The stress distribution obtained from two-curve fitting of Raman spectrum was in good agreement with that estimated by finite element analysis (FEA).

This paper investigates thermomechanical deformation behaviors of titanium-nickel (Ti-Ni) shape memory alloy (SMA) films in order to derive their constitutive relationships for a reliable design of Ti-Ni SMA microelectromechanical systems (MEMS) actuators. dc magnetron sputtering with block-on-disk target was employed to deposit composition-controlled Ti-Ni SMA films, characterized by uniaxial tensile testing with in situ X-ray diffraction (XRD) measurements. The XRD tensile tests enable us to measure the Poisson's ratio, as well as the Young's modulus of Ti-Ni films with various film compositions. At room temperature (RT), Ti-Ni films having Ti contents less than 50 atomic% (at.%) exhibit superelastic behavior, and those having Ti contents greater than 50 at.% exhibit shape memory behavior. The Ni-53.2 at.% Ti film, however, failed in a brittle manner at mere 0.8%, because precipitation hardening occurred with increasing Ti content. At elevated temperatures, Ti-Ni films having Ti contents of 50.2-52.6 at.% undergo phase change from martensite to austenite. The Young's modulus depends on temperature at each phase, regardless of film composition. But the Poisson's ratio is independent of both temperature and composition. However, film composition does affect the measured material constants, b(A), b(M), c(A), and c(M), that are used to construct the constitutive relationships. Stress-strain curves calculated from the constructed constitutive relationships are in close agreement for both the martensite and austenite phases with those obtained from tensile tests, so that the constitutive relationships are expected to find great utility in the design of Ti-Ni film-actuated MEMS. (c) 2006 Elsevier B.V. All rights reserved.

This paper describes a novel experimental technique for measuring mechanical properties of gold-tin (Au-Sn) eutectic solder film used for soldering package in microelectromechanical systems (MEMS). Dual-source DC magnetron sputtering was employed to deposit Au-20 weight % (wt%) Sn film. The tensile test with in situ X-ray diffraction (XRD) measurement evaluates the Young's modulus and Poisson's ratio at intermediate temperatures. The Young's modulus and Poisson's ratio at room temperature were found to be 51.3 GPa and 0.288, lower than bulk values. The Young's modulus decreased with increasing temperature, whereas the Poisson's ratio did not depend on temperature. The XRD tensile test also showed creep deformation behavior of Au-Sn film. We have developed a shear deformation test technique, which is performed by using Au-Sn film sandwiched by two single crystal silicon (Si) cantilever structures, to characterize the shear properties of the film. The shear moduli obtained from the shear deformation tests ranged from 11.5 to 13.3 GPa, about 38% lower than those from the XRD tensile tests. The measured shear strength from 12 to 17 MPa exhibited a temperature dependency. Information about the tensile and shear characteristics would likely to be of great use in designing Au-Sn soldering packages for MEMS. (C) 2007 NIMS and Elsevier Ltd. All rights reserved.

This paper describes the development of a novel silicon ( Si) cantilever beam device actuated by titanium-nickel ( Ti-Ni) shape memory alloy ( SMA) films. A Ti-Ni SMA film can yield high work output per unit volume, so a Ti-Ni film-actuated Si cantilever beam device is a prospective tool for use as a microelectromechanical system ( MEMS) probe card that provides a relatively large contact force between the probe and electrode pad in spite of its minute size. Before fabrication of the device, the thermomechanical deformation behavior of Ti-Ni SMA films with various compositions was investigated in order to determine a sufficient constituent film for a MEMS actuator. As a result, Ti-Ni films having a Ti content of 50.2 to 52.6 atomic% ( at%) were found to be usable for operation as a room temperature actuator. We have developed a Ti-Ni film-actuated Si cantilever beam device, which can produce a contact force by the cantilever bending when in contact, and also by the shape memory effect ( SME) of the Ti-Ni film arising from Joule heating. The SME of the Ti-Ni film can generate an additional average contact force of 200 mu N with application of 500 mW to the film. In addition to physical contact, a dependable electric contact between the Au film-coated probe tip and the Al film electrode was achieved. However, the contact resistance exhibited an average value of 25 Omega, which would have to be reduced for practical use. Reliability tests confirmed the durability of the Ti-Ni film-actuated Si cantilever-beam, in that the contact resistance was constant throughout a large number of physical contacts (> 10(4) times).

This paper describes novel MEMS probe card device, which is composed of silicon (Si) cantilever beams actuated by titanium-nickel (Ti-Ni) shape memory alloy (SMA) films. Since Ti-Ni SMA film can yield a higher work output per unit volume, Ti-Ni film-actuated Si cantilever beam is expected to be a MENIS probe card device providing large contact force between probe and electrode pad. The developed cantilever beam produces a contact force by not only cantilever bending in contact but also the shape memory effect (SME) of Ti-Ni film arising from Joule's heating. The SME of Ti-Ni film containing Ti of 50.5 atomic (at.) % to 53.2 at. % can generate an additional contact force of 200 mu N on average under applying an electric power of 500 mW to the film. Ti-Ni film-actuated Si cantilever beam would be a key element for successful MEMS probe card with larger contact force and smaller size.

The purpose of this work is to quantitatively clarify the shape memory behavior of Fe-Pd films containing similar to 30at%Pd by thermal cycling testing under various constant stresses. Fe-Pd films (4 pm thick) were deposited onto Si wafers with thermally formed 1 mu m-thick SiO2 layer using a dual-source dc magnetron sputtering apparatus. The deposited films were all annealed at 900 degrees C for 60 min followed by iced water quenching. Perfect shape recovery was observed for Fe-30.0at%Pd film when the applied stress was lower than 300 MPa. The maximum recoverable strain was similar to 0.6%. Fe-29.2at%Pd film, on the other hand, showed unrecovered strain after thermal cycling even if the applied stress was 40 MPa. XRD measurements of the Fe-29.2at% Pd film before and after thermal cycling revealed irreversible fcc-bct martensitic transformation that occurred during cooling process at a temperature around -80 degrees C. The critical stress of Fe-Pd films, at which plastic deformation commences to occur, is higher for films with 30 at% Pd than for films with 29.2 at% Pd, which is practically advantageous. The M, temperature of these films is lower than room temperature when no bias stress is applied, while it becomes higher than room temperature when appropriate bias stress is applied, obeying Clapeyron-Clausius law.

In this study, mechanical properties of micron-thick single crystalline silicon (Si) and electroplated nickel (Ni) films at intermediate temperatures are investigated by means of X-ray diffraction (XRD) tensile testing. The developed tensile test technique enables us to directly measure lateral (out-of-plane) elastic strain of microscale crystalline specimen using XRD during tensile loading, and determines Young's modulus, Poisson's ratio and tensile strength of the Si and Ni specimens. The specimens, measuring 10 mu m thick, 300 mu m wide and 3 mm long, are prepared through a conventional micro-machining process, and the ultraviolet lithographie galvanoformung abformung (UV-LIGA) process including a molding and an electroplating. The Si specimens, showing brittle fracture at room temperature (R.T.), have average Young's modulus and Poisson's ratio of 169 GPa and 0.35, respectively, in very good agreement with analytical values. The Ni specimens, showing ductile fracture, have those of 190 GPa and 0.24, lower than bulk coarse grained Ni. Young's moduli of both the Si and Ni specimens decrease with increasing temperature, but Poisson's ratios are independent of temperature. The influence of specimen size on elastic-plastic properties of the specimens is discussed.

This paper describes an experimental analysis of surface stress distribution on single crystal silicon (SCS) microstructures using laser Raman spectroscope. A handmade tensile tester was employed to apply an uniaxial tensile stress to SCS specimen with a 270nm-height and 4μm-square SCS convex structure in the gauge section. In room temperature, Raman spectroscope measured surface stress, applied by the tensile tester, around the convex. The stress distribution obtained from two-curve fitting of Raman spectrum was in good agreement with that estimated by finite element analysis.

This paper describes a novel evaluation method for in-plane Poisson's ratio of film materials. We have designed an on-chip bending test chip that can generate bending force to film specimen via torsion bars, when applying normal load to loading levers. Using surface micro machining technologies, the test chip has been fabricated from SOI wafer with 10μm devise layer thickness. Average value of in-plane Poisson's ratio was 0.063, which deviates only 2% from the ideal value of single crystal silicon. Therefore, this technique would be useful for Poisson's ratio evaluation of thin film materials.

This paper describes Raman spectroscopic stress analysis of single crystal silicon (SCS) microstructures for development of reliability evaluation technique utilized for silicon-based microelectromechanical systems (MEMS). An inhouse tensile tester was employed to apply a uniaxial tensile stress to the SCS specimen with a 270 run-height, 4 mu m-square SCS boss in the gauge section. Raman spectra on the boss were obtained under a constant tensile stress applied. The stress distribution obtained from two-curve fitting of Raman spectrum was in good agreement with that estimated by finite element analysis (FEA). The Raman spectroscopic stress evaluation method would be effective for nondestructive reliability testing for silicon-MEMS.

This paper describes a novel and simple method for measuring in-plane Poisson's ratio of film materials. We designed on-chip pure-bending test specimen where pure-bending deformation can be produced via torsion bar by application of normal load to loading lever. During pure-bending, the interference pattern of a family of hyperbola, corresponding to the contour tines of a film specimen in the out-of-plane direction, is observed with optical interferometer. In-plane Poisson's ratio of a film specimen can be obtained from only the angle of asymptotes of hyperbola consisting of the interference lines, regardless of other material constants. The measured Poisson's ratio of single crystal silicon (SCS) specimen was 0.063 on average, in close agreement within 2 % deviation from analytical value.

In this study, thermomechanical properties of titanium-nickel (Ti-Ni) shape memory alloy (SMA) films are investigated in order to derive constitutive relations. Ti-Ni SMA films, deposited by DC magnetron sputtering under controlled film composition, are characterized by uniaxial tensile tests. At room temperature (R.T.), Ti-Ni films having Ti contents less than 50 at% exhibit superelastic behavior, and those having Ti contents greater than 50 at% exhibit shape memory behavior. However, the Ni-53.2 at% Ti film fractured at a tensile strain of 0.8% because of an increase in brittleness with increasing Ti content. At elevated temperatures, Ti-Ni films having Ti contents of 50.2 to 52.6 at% undergo phase change from martensite to austenite. The Young's modulus of the Ti-Ni films depends on temperature at each phase, regardless of film composition. Film composition does, however, affect the measured material constants b(A), b(M), c(A), and c(M). Stress-strain curves calculated from the constructed constitutive equation closely agree with those obtained from tensile tests, for both the martensite and austenite phases. The constitutive equations are expected to find great utility in the design of Ti-Ni film-actuated microelectromechanical systems (MEMS). (c) 2005 Elsevier Ltd. All rights reserved.

In the present paper, we show that a-SiC films deposited from two independent Si and graphite magnetron sputtering sources have small tensile stress of similar to 100MPa without post-deposition annealing. Our sputtering apparatus has a rotation substrate holder that is designed to move to the front of individual targets alternately. In this experimental geometry, the relaxation period, when no deposition is made, must be present during sputtering. The presence of this relaxation period is found to be effective to change the compressive internal stress of deposited films into tensile direction. We have also succeeded to fabricate free-standing a-SiC soft X-ray filter with the thickness of 100-600 nm. The transmission spectra of these filters for soft X-ray beam showed good agreement with calculated ones. (c) 2005 Elsevier Ltd. All rights reserved.

It is well known that a sputtered metal film grows with inclined columns when the incident angle of sputtered particles inclines to the substrate normal. This phenomenon is usually explained by so-called self-shadowing effect. We have shown that the novel structured film, such as zigzag and/or helical columnar structure along with the growth direction, can be grown by changing the incident angle of sputtered particles into substrates during deposition. The relationship between sputtering conditions and film structures has also been investigated. Furthermore, the contact angle of a water drop on the Cr films with helical columnar structure was found to be much smaller than that on the inclined columnar film. This suggests that we can control the characteristics of surface by coating these novel columnar structured films.

This paper describes measurement of mechanical properties of micron-thin polycrystalline titanium nitride (TiN) films. We developed a novel tensile test technique that can directly measure lateral elastic strain of a microscale single/poly-crystalline specimen by means of X-ray diffraction (XRD), which enables evaluation of not only Young's modulus but also Poisson's ratio of TiN films. TiN films having thicknesses of 0.5 µm to 1.6 µm are deposited onto the top and bottom surfaces of a microscale single crystal silicon (Si) specimen. The deposition is carried out by r.f. reactive magnetron sputtering under Ar partial pressure ranging from 0.7 Pa to 1.0 Pa. Average values of Young's modulus and Poisson's ratio for the Si monolayer specimen are found to be 169 GPa and 0.35, respectively, which are in close agreement with analytical values. TiN films deposited under an Ar partial pressure of 0.7 Pa have average Young's modulus of 290 GPa and Poisson's ratio of 0.36. These values gradually decrease with increasing Ar partial pressure, but are independent of TiN film thickness. Fracture strength of a TiN/Si/TiN composite specimen shows dependence on film thickness, regardless of Ar partial pressure. © 2005, The Institute of Electrical Engineers of Japan. All rights reserved.

This paper describes a novel local heating technique for MEMS soldering and bonding technologies. Nanostructured aluminum/nickel (Al/Ni) multilayer films show self-propagating exothermic reactions, driven by a reduction in atomic bond energy. In this work, we demonstrate the validity of the Al/Ni reactive films as a heat source in manufacturing MEMS solder packages. Dual-source DC magnetron sputtering was employed to deposit the alternative layers of Al and Ni under controlling their thicknesses. By inducing spark, the Al/Ni multilayer film that generates heat enough to melt Au-Sn solder films is ignited, thereby having succeeded in fabrication of Au-Sn film-bonded MEMS elements. The local heating technique using Al/Ni multilayer film's exothermic reactions is expected to have the great potential as soldering technologies in MEMS.

This paper describes the effects of specimen size and temperature on viscoelastic properties of microscale SU-8 polymers at intermediate temperatures. Two different types of uniaxial tensile testers examine glassy/rubbery moduli, fracture strain and relaxation modulus of SU-8 polymer specimens. The average glassy modulus at R.T. is 3.5 GPa, which decreases with temperature elevations up to 573 K irrespective of specimen size. Yield stress and fracture strain, however, exhibit the size and temperature dependencies. Besides, we have constructed the master curves of relaxation modulus for micro/milliscale SU-8 polymer specimens. The master curve of microscale SU-8 polymers is in good agreement with that of milliscale polymers, which indicates that the apparent activation energy is independent of the size. The master curves approximated using a Prony series would be widely used to conduct viscoelastic finite element analysis, leading to reliable design of SU-8 micro-components. © 2005 IEEE.

This paper focuses on investigating mechanical properties of micron-thick polycrystalline titanium nitride (TiN) films. We propose a new technique that can directly measure lateral strain of microscale crystalline specimen by X-ray diffraction (XRD) during tensile test. The XRD tensile test can provide not only Young's modulus but also Poisson's ratio of TiN films. Micron-thick TiN films were deposited onto both surfaces of single crystal silicon (Si) specimen by r.f. reactive magnetron sputtering. Young's modulus and Poisson's ratio of Si specimen obtained by XRD tensile tests were in good agreement with analytical values. TiN films deposited at Ar partial pressure of 0.7Pa had the average values of 290GPa and 0.36 for Young's modulus and Poisson's ratio. The elastic mechanical properties of TiN films gradually decreased down to 220GPa and 0.29 with increasing Ar partial pressure up to 1.0Pa, regardless of film thickness. The change in the film properties with Ar partial pressure would be attributed to the change in the film density.

An Fe-Pd ferromagnetic shape memory alloy micro actuator is controlled. The actuator is displaced by raising temperature of the actuator by Jule heating because of shape memory characteristic. Controlling supplied voltage by PID control, displacement of the actuator is made to follow reference values. Finally, experimental results are shown. © 2005 SICE.

We present a new MEMS probe card, which is composed of silicon (Si) cantilever beams actuated by titanium-nickel (Ti-Ni) shape memory alloy (SMA) films. Since Ti-Ni film can yield a higher work output per unit volume, the Ti-Ni film-actuated Si cantilever beam has the potential as a MEMS probe card to generate a large contact force between a probe and electrode pad. The cantilever beam produces a contact force by not only cantilever bending in contact but also the shape memory effect (SME) of Ti-Ni film arising from Joule's heating. The SME of the Ti-Ni film containing Ti atom of 50.5% to 53.2% can generate an additional contact force of 200 mu N on average under applying an electric power of 500 mW to the film. The Ti-Ni film-actuated Si cantilever beam could be a key element for a successful MEMS probe card with larger contact force and smaller size.

The purpose of the present work is to clarify the fatigue behavior of Ni-25 mol%Mn-23 mol%Ga ferromagnetic,shape memory alloy at a temperature below martensite finish temperature. Low cycle fatigue tests for single crystal specimens were carried out using a custom-made compressive testing machine which was capable to change loading conditions without interruption. The specimens were deformed with formation and propagation of Luders bands, where rearrangement of martensite variants took place to accommodate strain under compressive loading. Fatigue failure occurred in transgranular mode by the connection of microcracks with two different directions formed at the Luders bands. The Luders band front was initially defined clearly, but it became unclear and wide due to the microcrack growth with increasing the number of cycles. Fracture surface was found to be lath-like, and it seemed to be consisted of the interface of martensite variants.

Ferromagnetic shape memory alloy Ni-25at%Mn-23at%Ga prepared by melting in an electric furnace was investigated to study compression properties at various temperatures with and without magnetic field. The magnetic field is applied parallel to the compression axis at a temperature below martensite finish temperature and at a temperature above austenite finish temperature. Triggering stress necessary for rearrangement of martensite variants is reduced by 0.76similar to1.68 MPa (i.e., 2.5similar to5.5%) when a magnetic field of 0.4similar to0.6 T is applied to martensite state. The stress reduction is larger at a higher magnetic field. On the other hand, triggering stress for stress-induced martensite transformation is essentially unchanged under the same magnetic field applied to austenite state. This is due in part to very small changes in Gibbs free energy under magnetic field because of large temperature differences between M-s and T-c. and because of essentially no difference in magnetization between martensite and austenite phases.

We have investigated the effect of deposition conditions on the crystal structure and optical properties of InN films deposited by reactive sputtering in pure nitrogen gas. InN films have been deposited onto glass, (0001) sapphire and (111) Si substrates by rf reactive puttering of pure In target. The nitrogen gas pressure, substrate temperature and applied rf power were varied in the range of 0.5-1.3 Pa, RTsimilar to600degreesC and 20-55 W, respectively. All deposited films had a wurtzite structure with strong <0 0 0 1> preferred orientation. In the case of the glass substrate, the full-width at half-maximum of InN0002 peak became large with increasing applied rf power and/or nitrogen gas pressure. The angular dispersion of the c-axis of films deposited onto sapphire increases with increasing substrate temperature. This behavior was similar to that of the films on glass substrates. The angular dispersion of the c-axis of films deposited on (111) Si at temperatures between 200degrees and 450degreesC was smaller than those films grown on the others. This may suggest the existence of some interactions between the growing InN film and (111) Si substrate. (C) 2004 Elsevier Ltd. All rights reserved.

Ta2O5 dielectric films were deposited on Si and quartz substrates by O-2 gas cluster ion beam (O-2-GCIB) assisted deposition at various incidence angles. The film structure and optical properties were significantly influenced by incidence angle. For films deposited using O-2-GCIB at 7 keV energy, when the incidence angle was smaller than 30degrees from the surface normal, a very smooth and dense film was realized and there were no significant difference in optical properties as the films deposited at normal incidence. However, when the incidence angle was higher than 45degrees, surface roughness increased and ripples were formed on the film surface. At a higher acceleration energy, which induces the sputtering of materials, previous reports have shown that in the case of Ar GCIB, ripple formation has been observed at an incidence angle larger than 45degrees. The same result was observed in the case of O-2 cluster ion beam assisted deposition.

等比組成のTi-Ni合金円板に純Tiチップを配した複合ターゲットをスパッタすることで48～52at%Niの組成範囲のTi-Ni薄膜を作製した。成長した薄膜は非晶質であったので、結晶化させると共に平滑な形状を記憶させるために熱処理を施した。DSC測定、引張り試験、及び一定荷重下での温度走査に伴う歪み変化の計測等から薄膜の形状記憶特性を評価し、マイクロアクチュエータに適した薄膜の形成条件を検討した。

This paper presents a novel strain measurement technique for determining Poisson's ratio of micron-thick polycrystalline TiN films. We developed a new compact tensile tester operating with X-ray diffraction (XRD) equipment in order to evaluate Young's modulus, Poisson's ratio and fracture strength of TiN films. TiN films having the thickness between 1.5 mum and 2.0 mum were deposited onto 9 mum or 24 mum-thick single crystal silicon (SCS) specimen by rf reactive magnetron sputtering. Young's moduli of TiN films deposited at Ar pressure of 0.7 Pa and 0.9 Pa were found to be 290 GPa and 240 GPa, respectively. Poisson's ratios of the films were, for the first time, determined to be 0.36 and 0.27 by out-of-plane normal strain measurements using XRD during tensile tests. The change in the mechanical properties of TiN films with Ar pressure should be attributed to the change in the film density. This technique proposed can be useful for accurately measuring Poisson's ratio of micron-thick single-and poly-crystalline MEMS films.

Shape change (strain) was observed for a polycrystalline thermoelastic ferromagnetic shape memory alloy Ni-9.5at.% Mn-27at.% Ga upon cooling and healing with and without magnetic field. The shape change occurred at martensite start temperature, M-S, and it was increased with increasing magnetic field. A large strain of 0.82% was observed when a magnetic field of 10 kOe was applied under a compressive stress of 126 MPa at 73 degreesC, several degrees above austenite finish temperature, A(f). This magnetic field effect on changes of M-S can be explained by a modified Clausius-Clapeyron relationship. (C) 2003 Elsevier B.V. All rights reserved.

Fe-Pd films have been deposited onto fused quartz substrates using a dual source dc magnetron sputtering apparatus, equipped with two independent targets of pure Fe and Pd. The Pd content of deposited films can be controlled with an accuracy of I at% Pd by varying the power for the Pd target at constant power for the Fe target. Fe-Pd films containing about 29 at% Pd show a fct structure after annealing at 900degreesC followed by quenching into iced water. These films underwent a thermoelastic fcc-to-fct martensitic transformation and the fct-phase region, where the fct phase is present at room temperature in the annealed films, has a tendency of shifting toward higher Pd content with increasing film thickness. This thickness effect is attributed to the difference in internal stress created during annealing. The martensite start temperature (M,) of films containing 28.5-30.0 at%Pd was higher than room temperature. and it became lower with increasing Pd content. When Fe-30 at%Pd films were separated from the quartz substrate, they showed shape memory behavior upon heating after deformation.

The purposes of this study are primarily to obtain basic knowledge of the fabrication of Fe-Pd ferromagnetic shape memory (SM) thin films and to investigate the effect of Pd content and thickness on the martensitic transformation behavior. Fe-Pd films were deposited onto fused quartz substrates by dual source sputtering. The crystal structures of as-sputtered films of Fe-28similar to30at%Pd and Fe-30similar to32at%Pd alloys were found to be bcc and fcc, respectively. It was observed that the crystal structure of Fe-28similar to30at%Pd films changed into a structure containing a fct phase after annealing at 900degreesC for 60 min followed by iced water quenching. The I'd content region where annealed films contain a fct structure tends to shift higher Pd with increasing film thickness. Annealed films containing fct phase underwent a thermoelastic fcc-to-fct martensitic transformation. The M-s temperature of films containing 28.5similar to30.0at% Pd was higher than RT, and it became lower with increasing Pd content. Fe-Pd films fabricated on thin Si substrates were found to show cyclic SM behavior under a constant magnetic bias force when temperature was changed repeatedly.

Ferromagnetic Ni-25at%Mn-23at.%Ga shape memory (SM) alloy was fabricated compositionally uniformly in vacuum using an electric furnace, and its polycrystalline specimens were deformed monotonically in compression and cyclically in compression-unloading-heating-cooling mode at room temperature. Polycrystals deformed in compression at various temperatures showed perfect SM effects and superelastic behavior, and using Clausius-Clapayron relationship, the martensite and its reverse transformation temperatures were determined. Polycrystals failed within several cycles when deformed cyclically at above M-f point, while no failure occurred up to 100 cycles at strain amplitudes between 1.1 and 4.4% when deformed cyclically at near M, point, although intergranular fracture occurred. The result suggests the Ni2MnGa alloy should be intrinsically ductile.

Fe-Pd films have been deposited onto fused quartz and silicon substrates by dc magnetron sputtering. When an arc-melted and homogenized Fe-30at.% Pd alloy disk was used as a sputtering target, Fe-Pd films fabricated was shown to contain about 24 at.% Pd under the deposition condition used. The target configuration was then modified by placing Pd wires on the target so as to control the Pd content of films with an accuracy of I at.% Pd. Fe-Pd films containing 28.5 at.% Pd underwent a thermoelastic fcc-to-fct martensite transformation after annealing at 900 degreesC followed by quenching into iced water. Apparently, the reverse transformation was also thermoelastic and the thermoelastic transformations occurred repeatedly upon thermal cycling. Some of the Fe-28.5at.% Pd films were peeled off from the quartz substrate and they showed SM effects upon heating after deformation. A diaphragm-shaped free-standing film was also fabricated on a thin Si substrate. This film showed attractive transformation characteristics, including a narrow transformation hysteresis loop of about 4 degreesC and a small temperature difference between M-f and A(f) (about 10 degreesC) in addition to M-s (43 degreesC) close to room temperature. This diaphragm-shaped film showed a reversible ballooning behavior with a maximum strain of about 0.05% upon thermal cycling. (C) 2003 Elsevier Science B.V. All rights reserved.

In order to clarify the effect of target materials on the reactive sputtering process, we have characterized the hysteresis behavior of four kinds of target materials, Ti, Nb, Cr and Al. When highly reactive metals such as Ti and Nb were used as taret, the hysteresis behavior appeared very clearly. On the other hand, the hysteresis became unclear when a low reactive metal such as Al was used. The hysteresis of Cr target was very small though the reactivity of Cr was not so low. This is attributed that the difference of sputtering yield between Cr metal and Cr-N nitride is smaller than that of the other metal. We have also investigated the optimum deposition conditions of sputtered Me-N films using the rf reactive sputtering apparatus equipped with a PEM (Plasma Emission Monitoring) control system for stabilizing the hysteresis behavior. The optimum condition for nitride films using highly reactive target metals such as Ti and Nb appeared to be near the unstable region of reactive sputtering process. The PEM system used in the study was found to be very useful for depositing these nitride films. In the case of AIN films, optimum condition was an excessive nitrogen partial pressure region. This difference in the optimum conditions is considered to be caused by the difference of reactivity of target metal and the stable metal-nitrogen alloy phase.

This paper presents the development of tensile test technique for evaluation of elastic properties of MEMS materials in order to reliably design MEMS. A compact tensile tester operating in X-ray diffraction system was newly developed to measure Young's modulus, Poisson's ratio and fracture strength of micro-sized single/poly crystalline materials. Changes of X-ray diffraction patterns with increasing a tensile stress directly derived lateral strains of single crystal silicon (Si) specimens. Averaged value of Young's modulus and Poisson's ratio of the specimens was 168 GPa and 0.270,respectively, in agreement with analytical values calculated from anisotropic theory. This technique has, therefore, great potential for evaluating mechanical properties of micro-sized materials.

We have studied the effect of ion flux on the properties of sputtered stainless steel films. To investigate the effect of ion flux, films have been deposited onto glass substrates using do planar magnetron-sputtering apparatus, which is equipped with an external magnetic coil. As the external coil current changes, the magnetic field of the magnetron cathode changes from balanced to unbalanced mode smoothly. Targets used were commercial SUS304 and SUS310S steel disks. The applied do power and Ar pressure were kept constant at 140 W and 0.5 Pa, respectively. The difference of the composition between as-deposited films and the target material appeared to be small. Films deposited using SUS304 target showed a bcc structure with (110) preferred orientation though the target material was metastable, austenitic stainless steel. When SUS310S steel with stable austenite was used as target material, as-deposited films consisted of a mixture of fcc and bcc phase. The ion flux showed very small effect on the structure and the composition of deposited SUS304 films. In the SUS310S films, however, the ion flux affected the volume ratio of fcc to bcc phase. Both films were superior in the corrosion resistance and the hardness as compared with bulk material. (C) 2002 Elsevier Science Ltd. All rights reserved.

We have studied the influence of the nitrogen partial pressure (PNZ) on composition, crystal structure, internal stress, resistivity and hardness of the rf reactive sputtered Cr-N films. Cr-N films have been deposited onto glass substrates by rf reactive magnetron sputtering using a plasma emission monitoring control system, where a signal in proportion to the light emitted by the sputtered Cr in the glow discharge plasma was used to control the admission of the reactive nitrogen into the system. Applied rf power and argon partial pressure (P-Ar) were kept constant at 140 W and 0.3 Pa, respectively. It is found that the composition of nitrogen in as-deposited films increases with increasing P-N2. Stoichiometric CrN films seemed to grow at a P-N2 of about 1similar to2 x 10(-2) Pa. The crystal structure of the film deposited at P-N2 lower than 1 x 10(-2) Pa is of hexagonal Cr2N, while the film deposited at P-N2 higher than 1 x 10(-2) Pa is of single phase CrN with an NaCl-type structure. The CrN film with good mechanical property is found to grow within a very narrow region of P-N2. (C) 2002 Elsevier Science Ltd. All rights reserved.

We have deposited Ti/C multilayer films onto glass and Si wafer substrates by do magnetron sputtering. The structure and the mechanical properties of multilayer films with various periods have been investigated. The multilayer films, of which periods were longer than 1.16 nm, showed diffraction peaks in low angle XRD patterns corresponding to their artificial layered structure. The Ti layer in the multilayer film was found to be amorphous when the period was less than about 5 nm. The roughness of Ti/C interface appeared to be larger than that of W/C multilayer system, which should be caused by a tendency of Ti layer to grow with a columnar structure. The hardness of Ti/C multilayer films was found to be constant when the period was larger than 2 nm. As the period decreased less than 2 nm, the hardness increased rapidly and reached nearly to the hardness of TiC single layer films. This should be caused by the increase in relative quantity of Ti-C bonds in the films.

A scanning vibrating electrode technique (SVET) was applied to make in-situ observations of stress corrosion cracking (SCC) in type 304 steel single crystals exposed to a 2.5 kmol m(-3) H2SO4 + 0.4 kmol m(-3) NaCl solution at room temperature. The three-dimensional (3-D) plots of corrosion current density during SCC can be successfully displayed with the SVET. Under the applied stress conditions of yield strength and above. the anodic current is observed locally at the site of crack nucleation along the mechanically induced slip-steps. Following the crack nucleation, the anodic current peaks disappear with the crack growth on 11101, planes. regardless of the test condition. It is. therefore. concluded that the SVET can be applied to make in-situ observations of crack nucleation and growth during stress corrosion. (C) 2001 Elsevier Science B.V. All rights reserved.

The corrosion resistance of a TiN surface prepared by plasma-based ion implantation (PBII) was compared with that of TIN coating films prepared by sputtering deposition, plasma spraying, and shielded vacuum are deposition. The corrosion test with the potentiodynamic polarization curve shows that the PBII sample had the best corrosion resistance. The SEM observation indicates that there was no pinhole on the TiN surface prepared by PBII. However, a lot of pinholes were observed in the TiN coating films prepared by the other dry coating processes. (C) 2001 Elsevier Science B.V. All rights reserved.

We have studied the effect of tensile axis on strain induced martensitic formation in SUS304 steel. Single crystal specimens having various tensile axes were deformed by the Instron type testing machine at 293 K. After deformation, quantitative analysis of α' martensite formed in specimens were carried out by using a newly developed apparatus. This apparatus estimates an amount of α' martensite with measuring the magnetic force between a specimen and a permanent magnet, of which force was calibrated by standard samples. The formation of α' martensite appeared to be classified into 3 groups. (1) In case of &lt 001&gt specimen, no martensite was found without necking down part. (2) In &lt 111&gt specimen, relatively small amount of martensite formation was found. (3) In specimen with the other tensile axes, large amount of martensite was formed. This classification agrees with previously reported hydrogen induced fracture.