ABSTRACT
Since the adoptation of the stepper for 64 Kbit dynamic random access memory mass-production line, it has stepper have been used for photolithography of LSI. Pellicle film composed of nitrocellulose was used as protection against the dust adhesion on the mask for g-line stepper. However, nitrocellulose film sustained damage with i-line exposure and optical transmittance and membrane stress decreased. Electron beam (EB) direct writing technology is suitable for fabrication of devices with submicron dimensions and ASICS chips in small-scale production. To improve the throughput of EB lithography, the shape of the electron beam was changed from a point beam to a fixed shaped beam and to a variable shaped beam. Proximity effect correction is one of most important key technologies in electron beam exposure lithography. X-ray lithography includes many technical issues, such as construction of small synchrotron radiation rings, vertical stepper and X-ray mask formation.
