AVS 52nd International Symposium
    Applied Surface Science Thursday Sessions
       Session AS+TF-ThM

Paper AS+TF-ThM7
Characterization of Ultra Shallow Arsenic Implants by ARXPS, LEXES, MEIS, and Dynamic SIMS

Thursday, November 3, 2005, 10:20 am, Room 206

Session: Thin Film Characterization
Presenter: G. Conti, Applied Materials
Authors: G. Conti, Applied Materials
Y. Uritsky, Applied Materials
H. Graoui, Applied Materials
M. Foad, Applied Materials
C.R. Brundle, Brundle & Associates
D. Kouzminov, Materials Analytical Services
C. Hitzman, Full Wafer Analysis
P. Mack, Thermo Electron Inc., UK
J. Wolstenholme, Thermo Electron Inc., UK
Correspondent: Click to Email
Ultra-shallow As implants are a leading-edge technology. Low voltage results in implant layers of tens of A thickness after anneal. Reliable metrology for shallow implants is needed. We characterize the implant layer as a function of nominal dose (1E14 to 2E15 ions/cm2) at 2KV, using a variety of techniques. Angle Resolved-XPS gives precise measurement of SiO2 oxide thickness, monitors the chemical state of As, and gives a non-destructive rough depth profile. Low Energy X-Ray Emission Spectroscopy, LEXES, gives a non-destructive As dose measurement, which depends on calibration against a bulk standard, for accuracy. MEIS gives a non-destructive depth distribution of atoms not in Si substitutional sites, and a dose calibrated by reference to amorphised Si. Dynamic SIMS provides very precise dose and depth distribution measurement to very low As concentrations, but is destructive and has a problem with the initial part of the depth scale and any As dose within it. Taken together a complete picture of the implant layer is obtained. Prior to annealing the As has a broad distribution, centered at about 50A depth. The outer oxide layer increases from 13A at 1E14 ions/cm2 dose to 18A for 2E15 ions/cm2 dose. ARXPS showed that samples from one particular implanter had a component of As2O3 very near the surface, well removed from the elemental As implant. The annealing conditions (N2 with 10% O2) double the oxide thickness (22A at 1E14 ions/cm2 dose; 38A at 2E15 ions/cm2), and cause the As to pile up just on the Si side of the SiO2/Si interface, but with a strong diffusion tail to 150A depth (SIMS). XPS shows that any oxide component is eliminated by anneal. A comparison of the MEIS to the SIMS depth distributions shows that the diffusion tail is in substitutional sites, and therefore not observable in the MEIS.