We have developed a new reticle exposure system, which can fabricate 150nm generation masks by means of a stitching exposure technique. We call this exposure system the Photomask Repeater, or high accuracy repeater (HR). HR is a modified i-line stepper for mask manufacturing with a field size of 22 by 22 mm in a single exposure. However, the device size on a 4x mask is larger than 22 by 22 mm. Furthermore the improvement in mask CD uniformity is required. For this purpose the exposure field size was extended with the use of 'seamless stitching technology'. This is the key to obtaining a feasible exposure system with the use of this method. Results have been achieved with this system showing CD variation of less than +/- 5 nm across a 1D seam band by means of a 'gradation filter'. Moreover, overall Cd uniformity is less than 13nm, while image placement accuracy is less than 24nm. HR is an attractive system for SoC mask manufacturing, and is also effective in reducing TAT.