AVS 52nd International Symposium
    Thin Films Monday Sessions
       Session TF-MoP

Paper TF-MoP5
Metalorganic Chemical Vapor Deposition and Characterization of Zr-silicate Gate Dielectrics

Monday, October 31, 2005, 5:00 pm, Room Exhibit Hall C&D

Session: Aspects of Thin Films Poster Session
Presenter: S. Lee, POSTECH, Korea
Authors: J. Kim, POSTECH, Korea
S. Lee, POSTECH, Korea
K. Yong, POSTECH, Korea
Correspondent: Click to Email
Zirconium silicate [ZrSi@sub x@O@sub y@] film, demonstrating good thermal stability in direct contact with Si, is a very promising candidate to replace SiO@sub 2@ (k=3.9) gate dielectrics. Zr-silicate films were deposited by injecting tetrakis-diethylamido-zirconium [Zr(NEt@sub 2@)@sub 4@] and tetra-n-butyl-orthosilicate [Si(O@super n@Bu)@sub 4@] precursors all together into metal-organic chemical vapor deposition (MOCVD) reactor. The growth rate was about 1 nm/min at 450~500 @super o@C. High-resolution TEM image of Zr-silicate films showed an atomically flat interface of silicate/silicon even in ultra thin films and showed smooth surface with RMS (root mean square) value of 0.5 nm. The Zr/(Zr+Si) ratio was average 0.2 for the bulk film, indicating a Si-rich composition. However at the silicate/silicon interface, it shows a higher Zr concentration than Si, implying a Zr-rich composition at the interface. Zirconium silicate films with ~30 % ZrO@sub 2@ were amorphous up to 800 @super o@C and above 900 @super o@C, phase separation of the films occurred into ZrO@sub 2@ and Zr-silicate phases. Amorphous silicates are desirable in order to avoid dislocations and grain boundaries, which provide pathways for diffusion of dopants from the electrode to the substrate and may exhibit high leakage paths. ZrSi@sub x@O@sub y@ exhibited a leakage current density of 1.6 x 10@super -4@ A/cm@super 2@ at a gate bias of 1 V for an equivalent oxide thickness of 4.3 nm and showed very low hysteresis volatage (delta VFB) below 0.02 V, which indicates the low impurities and defect contents in Zr-silicate films.