Accurate in depth profiling of As and P shallow implants by secondary ion mass spectroscopy

Abstract

Depth profiling of ultrashallow B implants in silicon using a magnetic-sector secondary ion mass spectrometry instrument J. Depth scale distortions in shallow implant secondary ion mass spectrometry profilesThe challenge for secondary ion mass spectroscopy is to accurately measure the profile shape for low-energy implants within the first few nanometers as well as to precisely determine the junction depth in the structure after any thermal treatment. Even if knowledge of the exact profile shape is not required for dose measurement, this information becomes essential for process modeling. This article presents results on the accurate determination in depth distribution of shallow As and P implants in Si. Sub-keV impact energy is investigated for O 2 ϩ and Cs ϩ primary ions. An in situ laser interferometer providing a real-time record of the sputter rate is used for the depth scale calibration. Fundamental and instrumental effects limiting the depth resolution, the sensitivity, and the accuracy are discussed.

SIMS depth profiling of ultrashallow P, Ge and As implants in Si using MCs2+ ions

“…The new generation of Cameca magnetic sector SIMS instruments offers these features together with a high mass resolution capability that is mandatory for phosphorous profile analysis. 2 Previous Cameca SIMS tools meet these requirements for O 2 C primary beam operation 3 but cannot routinely analyze negative secondary ions under Cs C bombardment with an impact energy of <2 keV. Measurements of As profiles with an impact energy of <2 keV for Cs C bombardment required the detection of positive secondary ions and application of the MCs C cluster technique (where M is the element of interest).…”

“…6 The optimal instrumental conditions for As implant profile analysis (15 keV, 1.5 ð 10 15 atoms cm 2 ) with this instrument were obtained using 1.1 keV Cs C impact energy and an incidence angle of 61°w ithout oxygen flood. More recently, a new method for the quantitative analysis of light electronegative elements (H, C, N, O) based on the detection of MCs 2 C ions has been developed and different processes for the formation of the MCs C and MCs 2 C ions have been proposed. 7 -9 For MCs C ions, the main process seems to be a recombination between a Cs C ion and a neutral sputtered atom M 0 .…”