AVS 50th International Symposium
    Thin Films Wednesday Sessions
       Session TF-WeP

Paper TF-WeP12
Ferroelectric Properties of Highly Oriented BLT Films for Ferroelectric-gate Field-effect Transistors

Wednesday, November 5, 2003, 11:00 am, Room Hall A-C

Session: Poster Session
Presenter: J.M. Lee, Chungang University, Korea
Authors: J.M. Lee, Chungang University, Korea
C.I. Kim, Chungang University, Korea
K.T. Kim, Chungang University, Korea
Correspondent: Click to Email
Ferroelectric thin films such as Bi-based layered perovskite (SrBi@sub 2@ Ta@sub 2@ O@sub 9@, Bi@sub 4@ Ti@sub 3@ O@sub 12@, Bi@sub 3.25@ La@sub 0.75@ Ti@sub 3@ O@sub 12@, etc.) and Pb(Zr,Ti)O@sub 3@ thin films have been extensively investigated for non-volatile ferroelectric random access memory (FeRAM) devices. Metal-ferroelectric-semiconductor field-effect-transistors (MFSFETs) have advantages of high switching speed, nonvolatility, and high density. However, the MFSFETs have been problem such as interdiffusion between the film and Si. To suppress them, a metal-ferroelectric-insulator-semiconductor (MFIS) structure has been demonstrated. The most important thing in developing a MFIS structure is to find a good insulator that acts as a buffer between the Si substrate and the ferroelectric material, and have relative high dielectric constants, low leakage current, good interface characteristics, and compatibility. The MFIS capacitors were fabricated using a metalorganic decomposition method. Thin layers of Al@sub 2@ O@sub 3@ were deposited as a buffer layer on SiO@sub 2@ /Si and BLT thin films were used as a ferroelectric layer. The electrical and structural properties of the MFIS structure were investigated by varying the Al@sub 2@ O@sub 3@ layer thickness. X-ray diffraction was used to determine the phase of the BLT thin films and the quality of the Al@sub 2@ O@sub 3@ layer. AES and TEM show no interdiffusion that suppressed by using the Al@sub 2@ O@sub 3@ film as buffer layer. The width of the memory window in the C-V curves for the MFIS structure increased with increasing thickness of the Al@sub 2@ O@sub 3@ layer. The experimental results show that the BLT-based MFIS structure is suitable for non-volatile memory FETs with large memory window.