A thin layer of Ta is introduced between Ti films and Si substrates in order to promote the formation of C54 TiSi2. After rapid thermal annealing (RTA) at 580degreesC, the single C40 TiSi2 phase is first found in the sample with a Ta interlayer, and compared with others' work, the crystalline quality of C40 TiSi2 is highly improved. The C54 TiSi2 phase is formed directly bypassing C49 TiSi2 when the samples are annealed at 650degreesC. The formation temperature of C54 TiSi2 is lowered by 100degreesC because of the formation of the pure C40 TiSi2 films. (C) 2003 Elsevier Science B.V. All rights reserved.