Along with the trend of reducing the critical dimension in photolithography, exposure wavelength has been shortened from 248nm to 193nm. Resin structures of resist including their chemical characteristics have been altered from PHS to acrylate polymer. On the other hand, 2.38wt% TMAH developer solution is widely used, which was optimized at the time of 436nm resist process. However, since the resist backbone and chemical characteristics of 193nm resist are different from that of 436nm resist. So, TMAH concentration of 2.38wt% is not necessarily the best value for 193nm process and may even worsen the process latitude. Therefore, we have studied improvement of the process latitude such as CD uniformity, pattern defect, and dissolution mechanism of 193nm resist in developer solution, by applying Diluted Developer Solution (DDS) on 193nm resist process.