The stacked structure of a semiconductor device is aggressively tried to solve the limit of device size, which has been reduced by the condensation of device design. To make the stacked device, we should make single crystal Si layer for upper transistors using the crystallization of amorphous Si layer deposited on the thick ILD layer. The fast process feedback is strongly needed to optimize and to check the process. We proposed electron back scattered diffraction (EBSD) method to monitor the Si crystallization process. The crystallization of a-Si film is monitored using the crystalline orientation map, the (001) crystal direction map and area, and the grain size distribution. For the mass production of devices, we are developing an in-fab metrology tool of EBSD