Publications Details
Quantitative Determination of Dielectric Thin-Film Properties Using Infrared Emission Spectroscopy
We have completed an experimental study to investigate the use of infrared emission spectroscopy (IRES) for the quantitative analysis of borophosphosilicate glass (BPSG) thin films on silicon monitor wafers. Experimental parameters investigated included temperatures within the range used in the microelectronics industry to produce these films; hence the potential for using the IRES technique for real-time monitoring of the film deposition process has been evaluated. The film properties that were investigated included boron content, phosphorus content, film thickness, and film temperature. The studies were conducted over two temperature ranges, 125 to 225 *C and 300 to 400 *C. The later temperature range includes realistic processing temperatures for the chemical vapor deposition (CVD) of the BPSG films. Partial least squares (PLS) multivariate calibration methods were applied to spectral and film property calibration data. The cross-validated standard errors of prediction (CVSEP) fi-om the PLS analysis of the IRES spectraof21 calibration samples each measured at 6 temperatures in the 300 to 400 "C range were found to be 0.09 wt. `?40 for B, 0.08 wt. `%0 for P, 3.6 ~m for film thickness, and 1.9 *C for temperature. By lowering the spectral resolution fi-om 4 to 32 cm-l and decreasing the number of spectral scans fi-om 128 to 1, we were able to determine that all the film properties could be measured in less than one second to the precision required for the manufacture and quality control of integrated circuits. Thus, real-time in-situ monitoring of BPSG thin films formed by CVD deposition on Si monitor wafers is possible with the methods reported here.