Controlled removal of a material by a chemical, plasma or physical process. etch selectivity compares removal rates for different materials; directionality compares removal rates along different geometric directions. High selectivity does not imply a vertical profile, and high directionality does not guarantee an undamaged surface.
A durable patterned layer used to protect underlying material during an etch. Its thickness and etch selectivity must survive the intended depth; erosion and lateral bias can change final feature dimensions even when the starting pattern is correct.
Chemical stripping of organic material, commonly photoresist, by reactive species produced in a plasma. oxygen radicals convert suitable organic material into volatile oxidation products. A remote source reduces direct energetic ion bombardment, but exposed materials can still oxidize and inorganic residue can remain.
An etch that removes a material in different directions without a strongly preferred geometrical direction. It can undercut an overhang and release a sacrificial layer, but can also widen a patterned opening. Access and transport can make the realized undercut nonuniform even with locally isotropic chemistry.
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Etching is a printmaking technique that involves using acid to carve designs into the surface of a metal plate, typically made of copper, zinc, or steel. The process generally involves the following steps: 1. **Preparation of the Plate**: The metal plate is cleaned and coated with a layer of wax or a similar material called a ground. This ground will resist acid.