LINEWIDTH AND UNDERLAYER INFLUENCE ON TEXTURE IN SUBMICROMETER-WIDE AL AND ALCU LINES

The local texture in three types of patterned, thin-film, Al and AlCu interconnections on Si semiconductor devices is investigated by electr on backscatter diffraction. Two types of standard planar metal structu res were investigated: (1) blanket Al and (2) blanket Al-0.5 wt % Cu o n TiN/Ti underlayers. Both were deposited on amorphous SiO2 substrates followed by reactive ion etching to define 0.45-10 mu m wide lines an d >10x10 mu m(2) pads. Damascene structures were also investigated in which Al-0.5 wt % Cu films were deposited into preformed Ti-lined amor phous SiO2 trenches, 0.3-5.0 mu m wide by 0.4 mu m deep, followed by c hemical-mechanical polishing to remove the metal overburden. For these three types of structures, distinctly different behaviors were observ ed: the two planar metal samples exhibited either little change or a l arge increase in their (111) fiber texture strength with decreasing li newidth, while the damascene samples showed a marked decrease in the ( 111) fiber texture with decreasing linewidth and feature size. In addi tion, a novel trimodal (111) texture distribution was found in 0.3 mu m wide damascene lines in which appreciable TiAl3 formed. (C) 1998 Ame rican Institute of Physics.