SiC-Au-stepper masks have been used for the fabrication of sub-micron devices by SOR based X-ray lithography in connection with a high precision alignment. As a test device we chosed a sub-micron transistor with four lithographic layers. The gatelength and the gate-width is scaled down from 2.0 pa to 0.5 wri, and 8.0 p.m to 1.0 p.m respectively. The SiC-mask blanks have been fabricated in a batch process by high temperature CVD deposition. Due to extensive process optimization SiC-membranes with a very smootA surface (RMS-roughness < 20 nm) and a Young's modulus as high as the bulk value (4.6•19 Pa) have been fabricated. Membranes of 2.5 4m in thickness having areas of up to 28 cm are being prepared with excellent transparency for synchrotron and optical radiation. For high X-ray absorption electroplated Au absorbing pattern have been applied. The combination of rigid SiC-membranes with a stress reduced Au-absorber (stress less than 1•10 Pa) will result in a mask distortion of less than 5 ppm even for a "worstcase" geometry of membrane and absorber pattern. Precise 0.5-micron pattern with an excellent control of the critical dimensions have been generated by e-beam lithography and electroplating, as well as mask copying by using synchrotron orbit radiation (SOR). Due to the excellent detection accuracy of the alignment pattern in case of SiC-masks (6 nm) a practical determined alignment accuracy of 40 nm has been obtained by using the MAX1 stepper at BESSY.