Projection and proximity printings are compared in terms of linewidth tolerance. Computer simulated exposure-defocus and gap-exposure diagrams are used to characterize the two techniques respectively. The depth of focus for projection printing in terms of the universal depth parameter k2 is evaluated as a function of the universal width parameter k1, for five long and short representative lithographic features, then three long features. Similarly, the depth of focus and working distance for proximity printing are evaluated for a O.25-jm system in x-ray and 2.5-,um system in uv and some preliminary comparison to experimental results is shown. The image contours and depth of focus of the two imaging techniques are compared. Proximity effects are present for both techniques. The distinction of working distance and depth of focus for proximity printing is observed for the first time. Against intuition, a shorter mask-to-wafer gap is not always better.

Date Published: 1 May 1990
PDF: 10 pages
Proc. SPIE 1263, Electron-Beam, X-Ray, and Ion-Beam Technology: Submicrometer Lithographies IX, (1 May 1990); doi: 10.1117/12.20147

Published in SPIE Proceedings Vol. 1263:
Electron-Beam, X-Ray, and Ion-Beam Technology: Submicrometer Lithographies IX
Douglas J. Resnick, Editor(s)