What is "etching"

Etch \Etch\, v. t. [imp. & p. p. Etched; p. pr. & vb. n. Etching.] [D. etsen, G. ["a]tzen to feed, corrode, etch. MHG. etzen, causative of ezzen to eat, G. essen ??. See Eat.]

1. To produce, as figures or designs, on mental, glass, or the like, by means of lines or strokes eaten in or corroded by means of some strong acid.

   Note: The plate is first covered with varnish, or some other ground capable of resisting the acid, and this is then scored or scratched with a needle, or similar instrument, so as to form the drawing; the plate is then covered with acid, which corrodes the metal in the lines thus laid bare.

2. To subject to etching; to draw upon and bite with acid, as a plate of metal.

   I was etching a plate at the beginning of 1875.
   --Hamerton.

3. To sketch; to delineate. [R.]

   There are many empty terms to be found in some learned writes, to which they had recourse to etch out their system.
   --Locke.

Etching \Etch"ing\, n.

1. The act, art, or practice of engraving by means of acid which eats away lines or surfaces left unprotected in metal, glass, or the like. See Etch, v. t.

2. A design carried out by means of the above process; a pattern on metal, glass, etc., produced by etching.

3. An impression on paper, parchment, or other material, taken in ink from an etched plate.

   Etching figures (Min.), markings produced on the face of a crystal by the action of an appropriate solvent. They have usually a definite form, and are important as revealing the molecular structure.

   Etching needle, a sharp-pointed steel instrument with which lines are drawn in the ground or varnish in etching.

   Etching stitch (Needlework), a stitch used outline embroidery.

1630s, verbal noun from etch (v.), also "the art of engraving;" 1760s as "a print, etc., made from an etched plate."

n. 1 (lb en uncountable) The art of producing an image from a metal plate into which an image or text has been etch with acid. 2 (lb en countable) The image created by this process. vb. (present participle of etch English)

1. n. an impression made from an etched plate

2. an etched plate made with the use of acid

3. making engraved or etched plates and printing designs from them [syn: engraving]

Etching is traditionally the process of using strong acid or mordant to cut into the unprotected parts of a metal surface to create a design in intaglio (incised) in the metal. In modern manufacturing, other chemicals may be used on other types of material. As a method of printmaking, it is, along with engraving, the most important technique for old master prints, and remains in wide use today. In a number of modern variants such as microfabrication etching and photochemical milling it is a crucial technique in much modern technology, including circuit boards.

Etching is used in microfabrication to chemically remove layers from the surface of a wafer during manufacturing. Etching is a critically important process module, and every wafer undergoes many etching steps before it is complete.

For many etch steps, part of the wafer is protected from the etchant by a "masking" material which resists etching. In some cases, the masking material is a photoresist which has been patterned using photolithography. Other situations require a more durable mask, such as silicon nitride.

Etching may refer to:

• Etching, a printmaking technique in art
• Glass etching, a glass decoration technique
• Industrial etching, or chemical milling, chemical etching in manufacturing and industry
• Photochemical machining, with chemicals, using a photoresist
• Etching (microfabrication), a process in producing microelectronics
• Ion track etching
• Unwanted glass etching done by dishwashers

Most of the above can be called chemical etching, though the term is mostly used for industrial etching. An etcher is most likely to mean a printmaker. An etchant (sometimes mordant) is any chemical used to etch, but probably refers to an industrial process.