The behavior of particulates in a capacitively coupled, 13.56 MHz radio frequency (rf) excited CH4 plasma was investigated by time-resolved laser:light scattering (LLS). The ballistic motion of the large particulates causes the LLS signal to fluctuate with peaks at the plasma sheath boundary. In an Ai plasma with a substrate which had been coated by diamondlike carbon film in the CH4 plasma process, a quasistatic particulate cloud formed and the LLS signal, the self-bias voltage, and-the optical emission oscillated slowly all with the same period. Also, the shape of the particulate cloud changed periodically. The time variation of the particulate’s mean size in the cloud was obtained by the angular dissymmetry measurement of scattered light intensities. The behavior of the particulates seemed to depend on the particulate size. The, time-resolved plasma potential obtained from the heated, fast scanning Langmuir probe Indicates that the formation of particulates influences the plasma state. The optical microscope and scanning electron microscopy were used to observe the morphology and the size of the particulates. Transmission electron microscopy and electron probe x-ray microanalysis studies indicate that they have an armorphous structure. Together with the observation of the collected particulates, the results of LLS studies showed that two different groups of particulates are generated in CH4 plasma. The optical emission spectra of the particulate-contaminated Ar plasma and the normal clean Ar plasma were obtained and compared. The difference between the two spectra indicates that the mean energy of the secondary electrons which come out of the powered electrode changes as a result of the interaction with the particulate cloud formed around the plasma-sheath boundary. The distribution bf; the particulate cloud was highly dependant on the rf power. The ion drag force due to the ambipolar diffusion flux from the central high plasma density region to the wall is thought to play an important role in particulate cloud distribution. A modified turn-off process is suggested to prevent particulates from falling on the wafer surface.