AVS 47th International Symposium
    Material Characterization Tuesday Sessions
       Session MC-TuP

Paper MC-TuP5
Development of Secondary Ion Mass Spectrometry Methodology for the Film Thickness Measurement of Sub-2nm SiO@sub 2@ Interlayers

Tuesday, October 3, 2000, 5:30 pm, Room Exhibit Hall C & D

Session: Poster Session
Presenter: J. Zhao, Advanced Micro Devices
Authors: C.M. Jones, Advanced Micro Devices
J. Zhao, Advanced Micro Devices
Correspondent: Click to Email
Film thickness of interfacial SiO@sub 2@ in poly-emitter devices and thickness of gate oxide in transistors is crucial to device performance and speed. The thickness regimes (0-1nm and 1.5-2.5 nm, respectively) are too thin to allow for accurate measurement by electron microscopic techniques. In the present work, we report the development of secondary ion mass spectrometry (SIMS) methodology for the film thickness measurement of sub-2nm SiO@sub 2@ interlayers. The SiO@sub 2@ interlayer structure is polycrystalline Si / SiO@sub 2@ / Si substrate. The polycrystalline Si layer can be up to a few hundred nano-meters thick. The sample is analyzed by SIMS and a concentration depth profile of oxygen is acquired. High-energy Cs bombardment is used, so that the thin SiO@sub 2@ layer is diluted by ion beam mixing. A 14.5 kV net impact energy provides sufficient mixing to change the composition of the interface from that of stoichiometric SiO@sub 2@ to Si with a high dose of oxygen. The areal density of the interfacial oxygen peak may be calibrated against a SIMS oxygen ion implant standard with a precision of better than 3%. The SiO@sub 2@ thickness is then calculated with equal precision, using the formula derived. A statistical measurement of the same sample over a period of several weeks demonstrated a superior reproducibility.