AVS 50th International Symposium
    Applied Surface Science Monday Sessions
       Session AS-MoM

Paper AS-MoM8
Determination of SiGe Film Composition and Thickness by Combined AES and Multiple-Voltage X-ray Emission Analysis

Monday, November 3, 2003, 10:40 am, Room 324/325

Session: Practical Surface Science
Presenter: J.T. Armstrong, National Institute of Standards and Technology
Authors: J.T. Armstrong, National Institute of Standards and Technology
S.A. Wight, National Institute of Standards and Technology
R.B. Marinenko, National Institute of Standards and Technology
D.S. Simons, National Institute of Standards and Technology
E.B. Steel, National Institute of Standards and Technology
Correspondent: Click to Email
SiGe epitaxially grown on Si is used for bandgap-engineered devices with significant potential in a variety of microelectronic products. The composition of SiGe layers is often determined by RBS; however, the analytical accuracy is limited to ~5-10%, in part due to the lack of suitable standards. We are working on development of higher accuracy analytical procedures to characterize SiGe films being considered as NIST reference materials (50-150 nm, 3-40 atom % Ge, grown on Si substrates). We use a combination of Auger electron spectroscopy, multiple voltage x-ray emission analysis, and SIMS to determine their homogeneity, thickness and composition. Results are compared to measurements made on a series of bulk SiGe alloys also being investigated as possible NIST reference materials. The new generation of field emission scanning Auger microprobes (FE-SAM) provides superior capabilities for this type of analysis. With our newly installed FE-SAM, we are able to simultaneously perform Auger electron spectroscopy and high precision and accuracy EDS x-ray analysis at beam energies ranging from <1 to 25 keV. Using low voltage EDS analysis (2-4 keV) (augmented by the lack of contamination enabled by UHV and incorporating our newly refined correction procedures) we are able to determine the film compositions to better than 2% relative. By multiple higher voltage x-ray analysis (5-25 keV) on the FEASAM and electron microprobe, we are able to determine the lateral homogeneity and thickness. By AES and SIMS we are able to determine the in-depth homogeneity of the films and separately estimate their thickness. Preliminary results show good agreement among these measurements.