Measurement of particles is crucial in wafer and photomask cleaning. In order to develop a simple method to quantify the number of particles on a semiconductor wafer, multiple internal reflection Fourier transform-infrared spectroscopy (MIR FT-IR) was used. The results using this measurement technique revealed that the number of polystyrene latex (PSL) particles deposited on a Si surface linearly increase with the concentration of PSL particles in deionized water. Furthermore, the ozonated deionized water (DIO3) process was superior to the sulfuric peroxide mixture (SPM) process in suppressing the deposition of PSL particles. Using this measurement technique in combination with scanning electron microscopy (SEM) measurements, the number of PSL spheres in a unit area could be estimated from the peak absorbance intensity of C-H2.