We have developed new 50 kV electron beam writer, EBM-4000, which is designed to fulfill the requirements for the 90 nm node mask. EBM-4000 makes use of the assets of our previous model, but major modifications are carried out on electron optics, writing circuits, and vacuum system. The written patterns are evaluated about CD uniformity, image placement accuracy, and throughput. The results indicate that CD uniformity and image placement accuracy meet the requirements for 90 nm node photomask, and EBM-4000 has a potential to extend its feasibility to 65 nm node photomask with acceptable throughput. (C) 2003 American Vacuum Society.