This study examined the effects of a Ti underlayer on the microstructure evolution of Cu(B)/Ti/SiO2 thin films upon annealing. For comparison, Cu(B)/SiO2 was annealed at temperatures ranging from 100 to 900 degrees C. In the case of Cu(B)/SiO2, abnormal grain growth abruptly occurred at approximately 400 degrees C and continued at temperature >= 400 degrees C. The growth was based on the formation of {111} twins along the < 112 > direction. In the case of Cu(B)/Ti/SiO2, the Ti underlayer reacts with B atoms to form titanium boride, which acts as a sink for the outdiffusion of B atoms. The redistribution of boron, as a result of the formation of titanium boride, has a significant influence on the microstructure evolution in Cu(B)/Ti/SiO2 samples at temperature >= 400 degrees C. Abnormal grain growth was observed at between 400 and 500 degrees C, which is believed to have been driven by strain energy minimization. At 600 degrees C and higher, B depletion from the grain interiors caused a relaxation of the elastic strain, resulting in normal grain growth. (C) 2007 Elsevier B.V. All rights reserved.