The measurement of thin film stress using phase shifting interferometry

Abstract A new technique for determining the stress of thin films is described. This technique combines digital phase shifting interferometry with image-processing software. A circular disc polished on one side is used as the coated substrate during film deposition. The average stress in thin films can be derived by comparing the deflection of the substrate before and after film deposition. The deflection of the substrate by the deposited film is obtained by the phase map. Using the Zernike polynomial fitting algorithm, a three-dimensional contour map is generated from the polynomial coefficients to visualize the deformation of the thin film and to examine the tensile or compressive stress after film deposition. Four oxide films prepared by ionbeam sputter deposition are investigated for their film stresses. The experimental results show that the stress values are concordant with measurements using other methods.

[1]  J. McNeil,et al.  Ion-assisted deposition of optical thin films: low energy vs high energy bombardment. , 1984, Applied optics.

[2]  R. W. Hoffman,et al.  Stress Anisotropy in Evaporated Iron Films , 1959 .

[3]  J. Sites,et al.  Ion Beam Sputter Deposition Of Optical Coatings , 1983 .

[4]  R. Glang,et al.  Handbook of Thin Film Technology , 1970 .

[5]  Anthony E. Ennos,et al.  Stresses developed in optical film coatings. , 1966, Applied optics.

[6]  F. d'Heurle,et al.  Aluminum films deposited by rf sputtering , 1970 .

[7]  Properties of ion-plated Nb2O5 films , 1989 .

[8]  H. Pulker,et al.  Mechanical stress in thin SiO2 and Ta2O5 films produced by reactive-low-voltage-ion-plating (RLVIP) , 1997 .

[9]  S. N. Sahu,et al.  A Laser Beam Deflection System for Measuring Stress Variations in Thin Film Electrodes , 1990 .

[10]  D. W. Hoffman,et al.  Stress-related effects in thin films , 1989 .

[11]  P. Flinn,et al.  Mechanical stress as a function of temperature for aluminum alloy films , 1990 .

[12]  K. Kinosita.  Recent developments in the study of mechanical properties of thin films , 1972 .

[13]  C J Kim,et al.  Polynomial fit of interferograms. , 1982, Applied optics.

[14]  P. Martin,et al.  Properties of thin films of tantalum oxide deposited by ion-assisted deposition , 1994 .

[15]  A. Thetford.  Optical shop testing: Edited by D. Malacara John Wiley, 1978, £21.15 , 1979 .

[16]  E. Irene,et al.  A measurement of intrinsic SiO2 film stress resulting from low temperature thermal oxidation of Si , 1986 .

[17]  Hyman Joseph Levinstein,et al.  Thermal stresses and cracking resistance of dielectric films (SiN, Si3N4, and SiO2) on Si substrates , 1978 .

[18]  R. W. Hoffman,et al.  Stresses in thin films: The relevance of grain boundaries and impurities , 1976 .

[19]  E. Klokholm.  An Apparatus for Measuring Stress in Thin Films , 1969 .

[20]  N. J. Salamon,et al.  Thin film stress from nonspherical substrate bending measurements , 1991 .

[21]  S. Askraba,et al.  A novel technique for the measurement of stress in thin metallic films , 1996 .

[22]  H. Hoffmann,et al.  Michelson interferometer for deformation measurements in an UHV system at elevated temperatures , 1976 .

[23]  A. Reisman,et al.  Stress Measurements of Thermally Grown Thin Oxides on (100) Si Substrates , 1989 .

[24]  G. Stoney.  The Tension of Metallic Films Deposited by Electrolysis , 1909 .

[25]  A simple technique to measure stress in ultrathin films during growth , 1995 .

[26]  T. Eiju,et al.  Digital phase-shifting interferometry: a simple error-compensating phase calculation algorithm. , 1987, Applied optics.