Laser generation and detection of surface acoustic waves: Elastic properties of surface layers

A noncontact all‐optical method for surface photoacoustics is described. The surface acoustic waves (SAWs) were excited employing a KrF laser and detected with a Michelson interferometer using a 633‐nm HeNe laser. Due to an active stabilization scheme developed for the interferometer a surface displacement of 0.2 A could be detected. The materials investigated included pure materials such as polycrystalline aluminum, and crystalline silicon; films of gold, silver, aluminum, iron, and nickel on fused silica; and a‐Si:H on Si(100). In the case of pure materials the shape of the acoustic pulse and the phase velocity were determined. The dispersion of the SAW phase velocity observed for the film systems was used to extract information on the film thickness, density, and transverse and longitudinal sound velocity. Models for the theoretical treatment of film systems and the calculation of dispersion curves are presented.

[1]  Paolo Cielo,et al.  Laser generation of convergent acoustic waves for materials inspection , 1985 .

[2]  Keiji Tanaka.  Elastic properties of covalent glasses , 1986 .

[3]  Y. Pao,et al.  On the determination of phase and group velocities of dispersive waves in solids , 1978 .

[4]  Gordon S. Kino,et al.  A unified theory for elastic wave propagation in polycrystalline materials , 1984 .

[5]  A. Karabutov.  FROM THE CURRENT LITERATURE: Laser excitation of surface acoustic waves: a new direction in opto-acoustic spectroscopy of a solid , 1985 .

[6]  N. Chubachi,et al.  Cut‐off characteristics of leaky Sezawa and pseudo‐Sezawa wave modes for thin‐film characterization , 1990 .

[7]  Grimsditch,et al.  Surface waves in Au/Cr superlattices. , 1987, Physical review. B, Condensed matter.

[8]  J. Wolfe,et al.  Phonon Scattering in Condensed Matter V , 1986 .

[9]  R. Dewhurst,et al.  Surface Acoustic Wave Interactions with Cracks and Slots: A Noncontacting Study Using Lasers , 1986, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control.

[10]  M. Grimsditch,et al.  Brillouin scattering from hydrogenated amorphous silicon , 1978 .

[11]  A. Neubrand,et al.  Study of attenuation and dispersion of optically excited surface acoustic waves employing small poly(vinylidene difluoride) foil transducers , 1989 .

[12]  Y. Nakagawa,et al.  Deposition of new piezoelectric Ta2O5 thin films and their surface acoustic‐wave properties , 1987 .

[13]  Thomsen,et al.  Surface generation and detection of phonons by picosecond light pulses. , 1986, Physical review. B, Condensed matter.

[14]  D. Royer,et al.  Analysis of thermal generation of Rayleigh waves , 1984 .

[15]  R. O. Dillon,et al.  Sound velocity in amorphous films of germanium and silicon , 1985 .

[16]  D. Wolf.  Computer simulation of elastic and structural properties of thin films. I. (001) orientation in fcc metals , 1990 .

[17]  A. A. Oliner,et al.  Acoustic surface waves , 1978 .

[18]  David A. Hutchins,et al.  A pulsed photoacoustic investigation of ultrasonic mode conversion , 1986 .

[19]  F. Cocks,et al.  On the thermoelastic properties of hydrogenated amorphous silicon , 1981 .

[20]  C. M. Scala,et al.  Time‐ and frequency‐domain characteristics of laser‐generated ultrasonic surface waves , 1989 .

[21]  N. Chubachi,et al.  Measurements of acoustic properties for thin films , 1982 .

[22]  S. Gracewski.  Surface wave generation by laser interference: Small penetration depth analysis , 1990 .

[23]  J. Monchalin.  Optical Detection of Ultrasound , 1986, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control.

[24]  Clemens,et al.  Relationship between interfacial strain and the elastic response of multilayer metal films. , 1988, Physical review letters.

[25]  Frank Jansen,et al.  Thermomechanical properties of amorphous silicon and nonstoichiometric silicon oxide films , 1987 .

[26]  R. Jackman,et al.  Photochemical processing of electronic materials , 1991 .

[27]  Danner,et al.  Surface acoustic waves in Ni/V superlattices. , 1986, Physical review. B, Condensed matter.

[28]  R. C. Weast.  Handbook of chemistry and physics , 1973 .

[29]  H. Känel,et al.  Characterization of crystal surfaces, thin films and superlattices by brillouin scattering from surface acoustic modes , 1989 .

[30]  A new ultrasonic method for measuring elastic moduli in unsupported thin films: Application to Cu‐Pd superlattices , 1990 .

[31]  H. F. Tiersten,et al.  Elastic Surface Waves Guided by Thin Films , 1969 .

[32]  Inspec.  Properties of amorphous silicon , 1985 .

[33]  K. Hesch,et al.  Process characterization and mechanism for laser-induced chemical vapor deposition of a-Si : H from SiH4 , 1988 .

[34]  H. Willems,et al.  Characterization of microstructure by backscattered ultrasonic waves , 1981 .

[35]  B. Auld,et al.  Acoustic fields and waves in solids , 1973 .

[36]  J. C. Baboux,et al.  Generating acoustic waves by laser: theoretical and experimental study of the emission source , 1988 .