AVS 46th International Symposium
    Thin Films Division Monday Sessions
       Session TF-MoP

Paper TF-MoP30
Preparation and Characterization of RF-sputtered SrTiO@sub 3@ Thin Films

Monday, October 25, 1999, 5:30 pm, Room 4C

Session: Poster Session
Presenter: K. Radhakrishnan, Nanyang Technological University, Singapore
Authors: K. Radhakrishnan, Nanyang Technological University, Singapore
C.L. Tan, Nanyang Technological University, Singapore
H.Q. Zheng, Nanyang Technological University, Singapore
G.I. Ng, Nanyang Technological University, Singapore
Correspondent: Click to Email
Strontium titanate, SrTiO@sub 3@ (STO) material has found wide applications ranging from capacitor dielectrics in ICs to semiconductor memories and submicron ICs. This paper focuses on synthesis of STO thin films on Si and GaAs substrates under various growth conditions such as oxygen partial pressure and substrate temperature, and post annealing conditions. STO films were deposited by RF-magnetron sputtering in Ar/O@sub 2@ plasma. The substrate temperature was 200 to 300°C. Platinum was used as electrodes. The dielectric constant increased with increase in O@sub 2@ partial pressure during sputtering. However, it showed a decreasing trend when the partial pressure ratio, O@sub 2@/Ar was >1. The dielectric constant measured for these samples is low (14 to 22). X-ray diffraction measurements (XRD) showed peaks mainly due to substrate with weaker peaks corresponding to STO phase. The STO samples were annealed to study the effect of annealing on dielectric constant. The films were annealed for 1 hr under O@sub 2@ flow. It was observed that the dielectric constant was around 20 when the films were annealed below 500°C. However, when the temperature was above 500°C the dielectric constant value increased five times. A high value of 125 was measured for the film annealed at 600oC. The increase in the dielectric constant was due to the development of stable STO phase when annealed under O@sub 2@. Films annealed above 500°C showed intense XRD peaks corresponding to STO phase for (110), (200) and (211). The effect of film thickness on the dielectric constant was determined using 100 to 425nm thick samples. The dielectric constant increased from 117 to a high value of 145 when the thickness was 425nm. The average breakdown voltage measured capacitors with STO film thickness of 110nm was found to be 855kV/cm.