$(1)(4$ points$)$ The design shown above is a negative refractive index device providing invisibility cloak function. The dimension and overall structure is given. Considering the size of the structure, the most reliable and feasible methodology is photolithography. Please explain why and how many photomasks would we need?

$(2)(8$ point$)$ Draw your fabrication process step by step.

$(3)(3$ points$)$ If you choose another method to make the same structure, what could be an alternative option? Please justify your decision.