The characteristics of CHF3 electron cyclotron resonance(ECR) plasma, which is formed in the case of a floating grid in an ECR-chemical vapor deposition system and +60V or -60V biased at grid, were investigated by an actinometric optical emission spectroscopy. It is found that the effects of grid and biasing on the distribution of radicals occur mainly at a low microwave input power. It is considered that the distribution of radicals at a low power is controlled by ele ctron collision and sheath potential together due to low electron temperature. H owever, the effect of sheath potential at a high power decreases due to increasi ng electron temperature. As a result, the distribution of radicals at a high pow er is dominated by electron collision.