Eli5 how are nanoscale metamaterials made through the process of photolithography?

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Eli5 how are nanoscale metamaterials made through the process of photolithography?

In: Engineering
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Photolithography lets you print patterns with very small details, on the micrometer or even nanometer scale. Basically, you apply a thin layer of plasticky light-sensitive “photoresist” to the object. Then, you put a “mask” in front of it and shine light through the mask. The mask has a pattern drawn on it, that lets light shine through except where the pattern blocks it. It’s like shadow puppets. Where the light shines through the mask and onto the photoresist, it weakens the photoresist. Then, you dip the object in a developer chemical which washes away the weakened areas of the photoresist. Now, the photoresist covering your object is not a solid layer, but instead it’s patterned with the pattern that was on the mask.

Now, you can do other processes to remove or add material to the object. You could use acid or other stuff to dissolve away the object, but the object will be protected where the photoresist pattern is. Thus, you’ll etch the pattern into the object. Or you can spray material onto the object, but the material will only get on the object through the holes in the photoresist pattern, so when you remove the photoresist entirely with other chemicals, that pattern will be sprayed on the object.

Metamaterials are things that have special properties because of patterns on them, so by putting patterns on objects like this, it turns them into metamaterials.