Assuming that a shield is placed horizontally on the top layer of the chip, the shield width is 150 nm, the shield wire thickness is 200 nm, a vertical target wire is on metal 2, the length of this...

Assuming that a shield is placed horizontally on the top layer of the chip, the shield width is 150 nm, the shield wire thickness is 200 nm, a vertical target wire is on metal 2, the length of this target wire is 3000 nm, and the shield to target layer depth is 5000 nm, what is the maximum shield space to protect against FIB-based probing attack whose maximum aspect ratio is 6? How many shield wires are needed to protect the target wire at least? Hint: Consider that a complete cut of shield wires can be detected and only consider perpendicular milling.