Fast method of measuring phosphorous concentration in PSG and BPSG films
AssigneeInmos Limited
InventorRonald A. Carpio
Life of this patent
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Abstract
A method of measuring the phosphorus concentration in phosphosilicate and borophosphosilicate films using infrared spectroscopy in conjuction with derivative spectroscopic techniques. This method is easily adapted for use with a Fourier Transform spectrometer. A spectrum of the film is taken with a dual beam infrared spectrometer. The second derivative of the spectrum is plotted to rersolve close peaks. Amplitudes of the P.dbd.O band at 1316 cm.sup.-1 and the O--Si--O band at 818 cm.sup.-1 are measured. A ratio between these amplitudes is calculated. The ratio is then matched to a calibration curve to determine the phosphorus concentration.
Claims12
A method of measuring phosphorus concentration in phosphosilicate film, which comprises:
- (a) depositing the film on a first wafer, and placing the first wafer for analysis in a dual beam infrared spectrometer;
- (b) using a reference in the reference beam of the spectrometer;
- (c) determining, with the spectrometer, a spectrum of the film;
- (d) calculating the second derivative of said spectrum;
- (e) determining from the second derivative calculation a value based on the P.dbd.O stretching band;
- and
- (f) referring to a calibration curve which relates the value to the phosphorus concentration in the phosphosilicate film.
Dependencies are inferred from the claim text.