Diffraction based overlay (DBO) metrology has fully demonstrated its remarkable advantages in terms of high resolution, high precision and low tool-induced shift (TIS) and so on . DBO technologies have been gradually replaced the traditional image based overlay (IBO) technologies and have also been developed to address the overlay metrology challenges for 22 nm technology node and beyond. In comparison with IBO technologies, the biggest problems that DBO faces now are high mark costs and long measurement time. IBO only uses single pad for two-dimensional (2D) overlay errors measurement, while DBO should adopt one-dimensional gratings for measurement with x, y directions. Furthermore, at least two marks are needed for one direction measurement. We introduce 2D periodic structure based DBO technologies. The DBO physical model is established through rigorous coupling wave analysis (RCWA) program. The feasibility of this method is proved by means of analysis of the overlay measurement sensitivity and main measurement errors. The application of 2D DBO measurement technology can help to reduce the measurement time and mark cost by half. The DBO measurement cost will thus be dramatically lowered, and the measurement efficiency will be promoted.