| Popis: |
The penumbral shadow has been recognized as the resolution- limiting parameter in x-ray lithography. In the present study, the exposure of resist with monochromatic (2.84 keV) x-rays and an experimental palladium spectrum is simulated for various values of the penumbral shadow. Two mask structures with an absorber wall angle of 0 and 17 degrees and an absorber thickness of 1 um are compared. The effects of the penumbra and the finite absorber thickness on line acuity, linewidth control and uniformity are demonstrated. The simulation is compared to electrical linewidth measurements of resistors fabricated in 300 nm poly-silicon films. Negative acting resist was patterned with palladium radiation at a penumbra of 0.3 um through a boron nitride supported gold absorber mask with a thickness of about 0.8 um. The data indicate that the experimental linewidth control is considerably smaller than calculated, especially for small x-ray doses. |
