Coherent anti-Stokes Raman spectroscopy has been used for in-situ diagnosis of Tadiofrequency discharge dissociation of silane. Based on the CARS intensity change of the Vi band of SiH4 we have studied the effects of EF power and total gag pressure on the dissociation rates of silane in SiH4-H2 and SiH4-N2 systems. In addition, the dissociation intermediates of silane have been detected by CARS technique with good signal to noise ratio and tentative assignment of the CARS spectrum has been made.