We report a him synthesis method called electron cyclotron resonance (ECR) plasma aided reactive pulsed laser deposition. Silicon nitride films were synthesized at low temperature by means of laser ablation of a silicon target in an ECR microwave discharge in pure nitrogen gas. It is found that silicon and nitrogen are well-distributed in the deposited films with a composition of near stoichiometric Si3N4. Optical emission spectroscopy indicated that nitrogen in the ECR plasma was highly activated. The presence of the ECR nitrogen plasma during the deposition is considered to lead to enhanced nitridation of the ablated silicon in the plume as well as at the substrate, and to be responsible for the effective incorporation of nitrogen in the films.