THE IMPROVEMENT OF ELECTRICAL PERFORMANCE OF TA DOPED BST THIN-FILMS

Electrical properties of the Ta doped BST thin films fabricated by two step process have been investigated. Ta doped BST thin films were pre pared by two step process, which consists of thin (10 nm) bottom layer formed at 600 degrees C and main layer deposited at 350 degrees C. Ta doped BST thin films (50 nm) deposited by one step process showed ver y low leakage current density of 2x10(-8) A/cm(2) at 1.5 V but exhibit ed large silicon oxide equivalent thickness of 0.95 nm. However Ta dop ed BST thin films of 50 nm deposited by two step process have small eq uivalent thickness of about 0.52 nm as well as low leakage current den sity of 3x10(-8) A/cm(2) at 1.5 V. With decrease of film thickness, ox ide equivalent thickness could be reduced to 0.47 nm and low leakage c urrent density of 4x10(-8) A/cm(2) could be obtained.