AVS 50th International Symposium
    High-k Gate Dielectrics and Devices Topical Conference Tuesday Sessions
       Session DI-TuM

Paper DI-TuM7
The Effect of Hf Content in Liquid Precursor on the Properties of Mist Deposited Ultra-Thin Films of HfSiO@sub 4@

Tuesday, November 4, 2003, 10:20 am, Room 317

Session: High-k Dielectric Growth and Processing
Presenter: K. Chang, The Pennsylvania State University
Authors: K. Chang, The Pennsylvania State University
K. Shanmugasundaram, The Pennsylvania State University
D.-O. Lee, Primaxx Inc.
P. Roman, Primaxx Inc.
P. Mumbauer, Primaxx Inc.
J.R. Ruzyllo, The Pennsylvania State University
Correspondent: Click to Email
Ultra-thin (<10nm) films of hafnium silicate formed by mist deposition method for gate dielectric application in advanced MOS devices were investigated. Precursors with Hf:Si ratio of 0.103:1, 0.276:1, and 1:1 were prepared to investigate the effect of Hf content on mist deposition process and film characteristics. MOS capacitors were fabricated for electrical characterization using Pt gate electrode. The Hf composition in the HfSiO@sub 4@ film was analyzed with angle-resolved X-ray photoelectron spectroscopy. The 1:1 precursor resulted in 12.6 at.% of Hf in the film and 7.5 at.% of Hf was obtained in the HfSiO@sub 4@ film deposited with 0.103:1 precursor. Deposition rate of HfSiO@sub 4@ linearly increases with the Hf content in the precursor even though the Hf composition in the film didn’t scale in the same order. Despite the difference in Hf content of the precursor, an interfacial oxide 2.2nm ~ 3.0nm thick was always detected by transmission electron microscopy. Through electrical characterization, it was determined that the obtained gate stacks feature an equivalent oxide thickness of 0.8nm ~ 1.5nm depending on the process. It is postulated that the lower EOT is caused by Hf diffusion from HfSiO@sub 4@ film during thermal treatment step and lower EOT of the interfacial layer. For lower EOT of the interfacial oxide, higher Hf content in the precursor is needed. Using 1:1 precursor, EOT 1.5nm HfSiO@sub 4@ thin film is deposited with leakage current density of less than 1×10@super -2@ A/cm@super 2@.