This paper presents a new deployment formulation in order to improve coverage in Sensor Networks. Sensor deployment is an important issue in designing sensor networks. This paper studies the geometric properties of voronoi diagram, addressing a divide-and-conquers deployment protocol in an area of interest. This novel methodology can deploy homogeneous sensor while heterogeneous sensor in whole area. By this methodology the solution of the deployment of each voronoi polygon can be formulated as nonlinear function. Simulation results show that this method can improve coverage within a short deploying time.