AVS 47th International Symposium
    Dielectrics Wednesday Sessions
       Session DI+EL+MS-WeA

Paper DI+EL+MS-WeA7
High-quality Ultrathin Fluorinated Silicon Nitride Gate Dielectric Films Prepared by Plasma Enhanced Chemical Vapor Deposition Employing NH@sub 3@ and SiF@sub 4@

Wednesday, October 4, 2000, 4:00 pm, Room 312

Session: Alternate Gate Dielectrics
Presenter: H. Ohta, Nagoya University, Japan
Authors: H. Ohta, Nagoya University, Japan
M. Hori, Nagoya University, Japan
T. Goto, Nagoya University, Japan
Correspondent: Click to Email
The silicon nitride (SiN@sub x@) film attracts much attention as scaled gate dielectric films in next generation@super ,@s ULSI. However, the conventional SiN@sub x@ film has a poor interface with silicon and is leaky due to a high trap density in the film. Recently, we have developed ultrathin fluorinated SiN@sub x@ films formed by ECR-PECVD employing NH@sub 3@/SiF@sub 4@. It is known that the average bond energy (5.73eV) of Si-F is higher than that of Si-H (3.18eV). Therefore, it is expected that the Si-F bond in the film should have improved the quality of gate dielectric film. In this study, we have investigated properties of ultrathin SiN@sub x@ films (4nm) formed at 350°C. These films (fluorinated SiN@sub x@ films) contain fewer hydrogen atoms than the conventional SiN@sub x@ films formed by ECR-PECVD employing NH@sub 3@/SiH@sub 4@. As-deposited fluorinated SiN@sub x@ films indicated the excellent hysteresis loop (20mV) in the C-V curve, and reduced the leakage current by several orders of magnitude than the thermal SiO@sub 2@ in the identical equivalent oxide thickness (EOT). These film properties and the surface reactions for the SiN@sub x@ film formation with good quality are discussed on the basis of results of the in-situ XPS, in-situ FT-IR RAS, FT-IR, and thermal desorption mass spectroscopy (TDS). As a result, the control of fluorine concentration in the SiN@sub x@ films was found to be a key factor for forming the fluorinated SiN@sub x@ films with high quality at low temperatures. The fluorinated SiN@sub x@ is very effective for ultrathin gate dielectric films in next generation@super ,@s ULSI.