CHARACTERIZATION OF AL-SI-CU METAL LINES BY MEANS OF TEM ANALYSIS ANDTHE SARF TECHNIQUE

Four groups of samples deposited at different temperatures, T-D, have been characterized by means of the SARF (Spectral Analysis of Resistan ce Fluctuations) technique. For each temperature, lines with the same length (800 mu m) and two different widths (1 mu m and 2 mu m) were av ailable. An accurate TEM (Transmission Electron Microscopy) analysis h as been carried out with the aim of investigating the dependence of th e microstructure on T-D. While 1-mu m-wide lines showed a quasi-bamboo structure, regardless of T-D, 2-mu m-wide lines appeared constituted by grains whose size was smaller than the stripe width. In this case, the grain size distribution was dependent on T-D. A new microstructura l parameter has been introduced to which electromigration noise seems to be very sensitive: the percentage of grains of the metal film whose size is smaller than the stripe width. The correlation observed among noise parameters, microstructural characteristics of the lines and, i n the case in which they were available, lifetime data, has confirmed the potentiality of the SARF technique as a diagnostic tool. (C) 1997 Elsevier Science Ltd.