On the phosphorus characterization in thin SiO 2 (P,B) CVD layer deposited onto a silicon substrate by PIXE

Abstract

In this work the capability of the PIXE technique to monitor a rapid and accurate quantification of P in thin SiO 2 (P,B) CVD layers (400 nm) deposited onto silicon substrate is discussed. In order to improve the sensitivity for P determination, a systematic study was undertaken using protons and helium ion beams at different energies using different thickness of Kapton X-ray absorbers. 600 keV proton or 1.5 MeV helium under normal incidence, using 146 μm Kapton as X-ray absorber, permits an accurate quantification of P with high sensitivity within few minutes of acquisition time. This sensitivity is highly improved when using grazing incidence angles (e.g. 80°), thus 1 MeV protons can be easily used. Finally, the PIXE results show that the phosphorus concentration in the CVD layer varies linearly with the percentage of the phosphine gas used in the CVD gas mixture.