OPTIMIZED EXTERNAL IR REFLECTION SPECTROSCOPY FOR QUANTITATIVE-DETERMINATION OF BOROPHOSPHOSILICATE GLASS PARAMETERS

Infrared (IR) external reflection spectroscopy has been optimized for the quantitative determination of composition and film thickness of bo rophosphosilicate glass (BPSG) deposited on silicon wafer substrates. The precision of the partial Least-squares calibrations for boron and phosphorus contents and thin-film thickness were measured as the cross -validated standard error of prediction statistic. The results showed that BPSG IR reflection spectra collected over a wide range of inciden t IR radiation angles (15 degrees, 25 degrees, 45 degrees, and 60 degr ees) can be used for the simultaneous quantification of these three BP SG parameters. When high angles of incidence were employed, the measur ement was found to be more sensitive to small errors in the angle of i ncidence. The polarization state of the incident IR radiation did not noticeably affect the prediction of the three calibrated BPSG paramete rs. The results achieved in this study provide guidelines for at-line process monitoring and quality control of BPSG thin films used in the fabrication of microelectronic devices.