《Microelectronics Process》Problem Set: Lithography

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 <A<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 ransistors with 0.5 um features 2)A0.6 um thick layer of resist has Qo=40 mJ/cm and Q=160 mJ/cm2. Calculate the resist contrast and CMTF. If the resist thickness is cut in half, Q reduces to 70 mJ/cm while Qo 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 tor(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 l keV and a mask to wafer separation of 20 microns

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