X-ray Diffraction Determination of Stresses in Thin Films

3 This paper presents the aethodology eaployed in the deteraination of the stress tensor for thin crystalline filas usine x-ray rockine curves . Use of the saae equipaent for the deteraination of the averaee stress in polyor non-c rystalline thin filas attached to a crystalline substrate is also di s cussed . In this case the lattice curvature of the substrate is deterained by measureaent of the shift in the Braee peak with lateral position in the substrate . Strains in sinele crystal layers aay be aeasured usine Braee diffraction fro• the layers and fro• the substrate or a reference crystal. with the highest strain sensitivity of any known technique . The difference in Brage ane l es for a strained and an unstrained crystal is related to the chanee in d spacing of the Brage planes , and the elastic strain is related to'this angular difference . The separation of two peaks on an x-ray rocking curve is generally not equal to the difference in Brage angles of two diffractine crystals , so diffractoaeter aeasureaents aust be carefully interpreted in order to obtain x-ray strains in crystalline filas (x-ray strains are strains relative to the reference crystal) . The unstrained d spacings of the fil• and the d spacings of the reference crystal aust be known to obtain the elastl c s t rains in the fila , fro• which the stress tensor is deterained .