3) Lithography - resolution (a) What types of diffraction are relevant to shadow printing and projection printing? How does diffraction determine optical resolution in either case? What three parameters can be improved to achieve better optical resolution in lithography? What 3 ways can be used to enhance lithographic resolution (e.g. resolution enhancing techniques)? (b) Determine the lithographic resolution in a proximity printing system if we are using an ArF source, the resist thickness is 2 μm and the gap separation is 15 μm. What would the best glass to use for the mask in this case and why? (c) Using projection printing, what is the resolution for an ArF source if we are using an air- mediated (n=1) optical lens system with sin a = 0.93? What is the resolution if done with ultrapure water as the medium? Assume k₁ = 0.25 (the practical limit).