Quantitative Determination of Borophosphosilicate Glass Thin-Film Properties Using Infrared Emission Spectroscopy

Abstract

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 so that the potential for using the IRES technique for real-time monitoring of the film deposition process could be 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 latter 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) from the PLS analysis of the IRES spectra of 21 calibration samples each measured at six temperatures in the 300 to 400 °C range were found to be 0.09 wt % for B, 0.08 wt % for P, 3.6 nm for film thickness, and 1.9 °C for temperature. Upon lowering the spectral resolution from 4 to 32 cm−1 and decreasing the number of spectral scans from 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.

Monitoring Dielectric Thin-Film Production on Product Wafers Using Infrared Emission Spectroscopy

“…16 The temperature variations were ascribed to lack of reproducible contact between the sample and the heater and/or the sample and the thermocouple when placing a sample in the emission apparatus. The temperature variations are potentially a significant source of error in the measurement of film properties on product wafers.…”

“…We have recently shown that nondestructive determination of thin-lm dielectric properties on monitor wafers can be m ade with the use of infrared emission spectroscopy (IRES). [13][14][15][16] These experiments illustrated that although IR emission data collected from BPSG thin-lm samples are complicated, it is possible to collect highly precise spectra on a time scale that is fast relative to the CVD process. Multivariate analysis methods applied to these spectra then provide rapid m easurements of B content, P content, lm temperature, and lm thickness.…”

Distinguishing between organic and inorganic phosphorus in hydroxyapatite by elemental analysis

“…Determination of the phosphorus content in soil, 1 glass 2 and phosphorus – containing compounds has been extensively evaluated by spectrophotometric methods. 3 , 4 The phosphorus capacities of orthophosphates, condensed phosphates, and phosphorus ligands bound to organic polymers can be measured using the vanadate-molybdate reagent.…”

Analysis of waveguide silica glasses using Raman microscopy

“…Fourier transform infra-red spectroscopy (FTIR) [14][15][16][17], infra-red external reflection absorption spectroscopy (IRRAS) [18] and infra-red emission spectroscopy (IRES) [19] have all been used to analyze for boron and phosphorous content in BPSG. These infra-red spectroscopic techniques give valuable structural information in addition to compositional analysis but, unfortunately the wavelengths involved limit their ability to target and analyze particular regions of planar waveguide structures.…”