Massachusetts Institute of technology 3.155J/6.152J Microelectronics Processing Technology Fall Term 2003 Problem Set: Lithography Out: October 8. 2003 Due: October 15. 2003 1)Plot resolution and depth of field as a function of exposure wavelength for a projection aligner with 100nm
Massachusetts Institute of Technology 3.155J / 6.152J Microelectronics Processing Technology Fall Term 2003 Problem Set: Lithography Out: October 8, 2003 Due: October 15, 2003 1) Plot resolution and depth of field as a function of exposure wavelength for a projection aligner with 100nm < λ < 500nm. Assume NA = 0.26. Recalculate on the same plot for NA = 0.41. Discuss the implication of these plots for the technologist that must manufacture transistors with 0.5 µm features. 2) A 0.6 µm thick layer of resist has Q0 = 40 mJ/cm2 and Qf = 160 mJ/cm2 . Calculate the resist contrast and CMTF. If the resist thickness is cut in half, Qf reduces to 70 mJ/cm2 while Q0 is unchanged. Assuming NA = 0.4, use the figure below to determine the minimum linewidth for an aligner with S = 1.0 using both resist thicknesses with a source of 365 nm. The figure below plots MTF of the aligner for a set of lines and spaces. The lines and spaces are of equal width (W), and the spatial frequency is normalized by the Rayleigh criteria, R. In other words, a normalized spatial frequency of 0.5, corresponds to a linewidth W equal to R (since the equivalent source spacing of the lines is 2W. 3) Estimate the diffraction-limited resolution for an X-Ray exposure system using photons with an energy of 1 keV and a mask to wafer separation of 20 microns