Cu damascene interconnects with crystallographic texture control and its electromigration performance

Abstract

The effect of underlayer texture on Cu film properties and electromigration performance in Cu damascene interconnects have been studied. The Cu film orientation depends strongly on the underlayer texture. The Cu<111> orientation can be controlled by changing the preferred orientation of the TiN underlayer, which has the same cubic structure as the Cu. The Cu film deposited on a highly <111>-oriented TiN underlayer indicates a strong <111> orientation. The atomic arrangement between Cu(111) and TiN(111) planes has a rotational angle within /spl plusmn/10/spl deg/ around the <111> axis in spite of lattice mismatch of 14.7%. In the case of damascene interconnects, sidewalls in a trench affect Cu texture and the dependence of the underlayer texture on the Cu film orientation becomes small as line width decreases. EM performance, however, has been improved by the realization of Cu damascene interconnects with a strong <111> orientation.