Half Micron Cmos Device Fabrication Using Hybrid Lithography With X-Ray And Optical Steppers

Hybrid lithography technology, using a newly developed X-ray stepper and a conventional optical stepper, was applied to half micron CMOS device fabrication. X-ray lithography was applied to four principal mask levels in thirteen lithography steps. In order to correct the geometrical run out in X-ray lithography levels, every die on X-ray masks had been shrunk to 99.99%, in length, of the original pattern. For realizing sufficient resolution and mask alignment accuracy, X-ray mask to wafer spacing was kept at 15 ±lμm, during the mask alignment and X-ray exposure process. Several advanced technologies, such as X-ray exposure in open air, protecting the resist from oxygen, and deep UV curing for X-ray resists, were applied. As a result, a half micron 101 stage CMOS ring-oscillator, which was designed with a submicron alignment margin, has been successfully fabricated, using a single layer resist process.