DOI: 10.1051/jp3:1997265
J. Phys. III France 7 (1997) 2375-2381

Strain Measurements in Thin Film Structures by Convergent Beam Electron Diffraction

A. Armigliato¹, R. Balboni¹, A. Benedetti¹, S. Frabboni², A. Tixier³ and J. Vanhellemont<sup>4

1</sup>  CNR Istituto Lamel, via P. Gobetti 101, 40129 Bologna, Italy
²  INFM and Dipartimento di Fisica, Università di Modena, via Campi 213/A, 41100 Modena, Italy
³  SGS-Thomson Microelectronics s.r.l., via C. Olivetti 2, 20141 Agrate Brianza, Italy
⁴  IMEC, Kapeldreef 75, 3001 Leuven, Belgium

(Received 3 October 1996, accepted 9 May 1997)

Abstract
The Convergent Beam Electron Diffraction technique (CBED) has been applied to determine the lattice strain in Si _1-xGe _x/Si heterostructures and below patterned films on silicon substrates. The well known problem of the stress relaxation which occurs in thinned TEM samples has been overcome, in the case of the heterostructures, by applying the isotropic elasticity theory to the lattice constants measured along different crystallographic directions through the shift of the High Order Laue Zone (HOLZ) lines in the central disk of the CBED patterns. In this way bulk strain values have been obtained, in good agreement with values deduced from independent techniques. In patterned structures, the high spatial resolution of the CBED technique has been applied to determine the distribution of the components of the strain tensor induced into oxidized silicon substrates by Si ₃N ₄ stripes. A good agreement with the results obtained using numerical computations has been found.

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