AVS 47th International Symposium
    Material Characterization Monday Sessions
       Session MC-MoM

Paper MC-MoM5
Matching the High Dose Ultra Shallow As Doping Profiles Measured by X-ray Photoelectron Spectroscopy, Magnetic Sector Secondary Ion Mass Spectrometry and Low Energy Quadrupole Secondary Ion Mass Spectrometry

Monday, October 2, 2000, 9:40 am, Room 207

Session: Depth Profiling
Presenter: T. Neil, Advanced Micro Devices
Authors: J. Zhao, Advanced Micro Devices
C.M. Jones, Advanced Micro Devices
T. Neil, Advanced Micro Devices
D. Zhou, University of Central Florida
Correspondent: Click to Email
SIMS has proven to be a powerful technique for dopant depth profile analysis, however, quantification of dopant concentrations in the outermost several nanometers is still not at all trivial. A major problem arises because SIMS analysis exhibits a surface transient before reaching equilibrium in the sputtering process. Ion yields and sputtering-rate vary significantly during the transient zone and after reaching the equilibrium. The surface transient can be reduced to a few nanometers if a low-energy primary ion beam is used, but a further reduction is hindered by the presence of native oxide of varying thickness on Si wafers. For ultra-shallow As doping profiles using Cs@super +@ primary ions, which increases the negative secondary ion yields, surface oxide significantly depress the As@super ?@ negative ion yield. In the present work, an attempt of using XPS depth profiling to determine the high dose ultra-shallow As dopant profile, with particular interests in the dopant distribution and concentration within the surface transient region, was reported. XPS quantification is free from the ion yield and erosion rate variations of SIMS quantification, and a detection limit of 3e19at/cm@super 3@ for As is demonstrated. XPS results show higher As concentration up to ten times at the sample surface region (<10nm) than that of magnetic sector SIMS result. In addition, the feature of As piled up at the interface of surface oxide and Si substrate was clearly detected in the XPS depth profile, but missed in the magnetic sector SIMS depth profile. After the first 10nm, XPS and magnetic sector SIMS depth profiles match each other, and magnetic sector SIMS demonstrates a superior detection limit down to 5e16at/cm@super 3@. A comparison of the As dopant profiles measured by low energy quadrupole SIMS and magnetic sector SIMS, which was corrected by XPS for the surface transient region, will be further discussed in the paper.