Dry etching refers to the removal of material, typically a masked pattern of semiconductor material, by exposing the material to a bombardment of ions (usually a plasma of Nitrogen, Chlorine and Boron Trichloride) that dislodge portions of the material from the exposed surface. Unlike with many (but not all, see isotropic etching) of the wet chemical etchants used in wet etching, the dry etching process typically etches directionally or anisotropically. Derka semiconductor is a material with an electrical conductance that is intermediate between that of an insulator and a conductor. ... ... General Name, Symbol, Number nitrogen, N, 7 Chemical series nonmetals Group, Period, Block 15, 2, p Appearance colorless Atomic mass 14. ... General Name, Symbol, Number chlorine, Cl, 17 Chemical series halogens Group, Period, Block 17, 3, p Appearance yellowish green Atomic mass 35. ... In semiconductor technology isotropic etching is non-directional removal of material from a substrate via a chemical process using an etchant substance. ... Wet etching is the removal of material by immersing the wafer in a liquid bath of chemical etchant. ...

Dry etching is used in conjunction with photolithographic techniques to attack certain areas of a semiconductor surface in order to form recesses in material, such as contact holes (which are contacts to the underlying semiconductor substrate) or via holes (which are holes that are formed to provide an interconnect path between conductive layers in the layered semiconductor device) or to otherwise remove portions of semiconductor layers where predominantly vertical sides are desired. Photolithography is a process used in semiconductor device fabrication to transfer a pattern from a photomask (also called reticle) to the surface of a substrate. ...