The semiconductor industry is investigating metrology methods and tools to ensure the high accuracy and stability required for chip making. Lithography equipment manufacturers are under constant pressure to provide in situ measurements that prevent wafer processing form slipping from the established parameters. This is especially true for DUV exposure tools utilizing excimer lasers with high repetition rates. Dose metrology is one of the key parameters for linewidth control in photolithography. This paper discusses current developments in dose metrology for 248, 193, and 157 nm wavelengths. Particular emphasis is placed on the methodology to support dose stability over the lifetime of the tool. Aspects of tool-to-self and tool-to- tool matching are examined in detail, as well as the implications of the mix-and-match use of lithography equipment. To ensure the long-term accuracy of present tools, strong cooperation is needed within the semiconductor industry from suppliers and end users; and beyond, from standards organizations and international consortia. This paper describes the tasks that have to be accomplished to sustain the dose metrology during the transition from the existing tools to future generations of optical micro lithographic tools.