Isotropic etching
Encyclopedia
In semiconductor
technology
isotropic etching is non-directional removal of material from a substrate via a chemical process using an etchant
substance. The etchant may be a corrosive liquid or a chemically active ionized gas, known as a plasma
.
Isotropic etching is most easily understood by comparison to anisotropic (or non-isotropic) etching. The most important commercial application of anisotropic etching is in semiconductor
chip processing, where photolithography
is used to print resist lines on silicon
wafer
s. To adequately reproduce very tiny lines (below 0.1 micrometer) into underlying silicon and metal layers on a wafer held in the horizontal plane, the direction of etching must be vertical only. The etchant may not be permitted to spread in the horizontal plane.
Isotropic etching may occur unavoidably, or it may be desirable for process reasons.
Semiconductor
A semiconductor is a material with electrical conductivity due to electron flow intermediate in magnitude between that of a conductor and an insulator. This means a conductivity roughly in the range of 103 to 10−8 siemens per centimeter...
technology
Technology
Technology is the making, usage, and knowledge of tools, machines, techniques, crafts, systems or methods of organization in order to solve a problem or perform a specific function. It can also refer to the collection of such tools, machinery, and procedures. The word technology comes ;...
isotropic etching is non-directional removal of material from a substrate via a chemical process using an etchant
Etching (microfabrication)
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....
substance. The etchant may be a corrosive liquid or a chemically active ionized gas, known as a plasma
Plasma (physics)
In physics and chemistry, plasma is a state of matter similar to gas in which a certain portion of the particles are ionized. Heating a gas may ionize its molecules or atoms , thus turning it into a plasma, which contains charged particles: positive ions and negative electrons or ions...
.
Isotropic etching is most easily understood by comparison to anisotropic (or non-isotropic) etching. The most important commercial application of anisotropic etching is in semiconductor
Semiconductor
A semiconductor is a material with electrical conductivity due to electron flow intermediate in magnitude between that of a conductor and an insulator. This means a conductivity roughly in the range of 103 to 10−8 siemens per centimeter...
chip processing, where photolithography
Photolithography
Photolithography is a process used in microfabrication to selectively remove parts of a thin film or the bulk of a substrate. It uses light to transfer a geometric pattern from a photomask to a light-sensitive chemical "photoresist", or simply "resist," on the substrate...
is used to print resist lines on silicon
Silicon
Silicon is a chemical element with the symbol Si and atomic number 14. A tetravalent metalloid, it is less reactive than its chemical analog carbon, the nonmetal directly above it in the periodic table, but more reactive than germanium, the metalloid directly below it in the table...
wafer
Wafer (electronics)
A wafer is a thin slice of semiconductor material, such as a silicon crystal, used in the fabrication of integrated circuits and other microdevices...
s. To adequately reproduce very tiny lines (below 0.1 micrometer) into underlying silicon and metal layers on a wafer held in the horizontal plane, the direction of etching must be vertical only. The etchant may not be permitted to spread in the horizontal plane.
Isotropic etching may occur unavoidably, or it may be desirable for process reasons.