Interface and oxide properties of rf sputtered Ta2O5- Si structures

✍ Scribed by T Dimitrova; E Atanassova

• Publisher: Elsevier Science
• Year: 1998
• Tongue: English
• Weight: 201 KB
• Volume: 51
• Category: Article
• ISSN: 0042-207X
• DOI: 10.1016/s0042-207x(98)00148-1

✦ Synopsis

Interface and oxide properties of Ta 2 O 5 -Si structures with rf sputtered Ta 2 O 5 of 7-80 nm thickness have been investigated using capacitors on p-Si and transistor-like test structures. It is found tha the electrical properties of the films are dominated by an extremely thin SiO 2 layer which is unavoidably formed at the interface Si-Ta 2 O 5 during rf sputtering. The as-deposited layers exhibit a large defect density in the form of oxide charges and acceptor type interface states, which are thickness dependent. A high density of interface states in the upper half of the Si band gap is detected. High temperature annealing at 1123 K in oxygen is effective for the reduction of the fixed oxide charges, that are reduced by about two orders of magnitude. The nature of the electrically active centres is proposed to be defects such as weak dangling Ta-O bonds and/or Si-O bonds.