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Etching is used in microfabrication to chemically remove layers from the surface of a wafer during manufacturing. Etching is a critically important process module in fabrication, 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 ...
Anisotropy (/ ˌænaɪˈsɒtrəpi, ˌænɪ -/) is the structural property of non-uniformity in different directions, as opposed to isotropy. An anisotropic object or pattern has properties that differ according to direction of measurement. For example, many materials exhibit very different physical or mechanical properties when measured along ...
Isotropic etching. Isotropic etching is a method commonly used in semiconductors to remove material from a substrate via a chemical process using an etchant substance. The etchant may be in liquid-, gas- or plasma -phase, [1] although liquid etchants such as buffered hydrofluoric acid (BHF) for silicon dioxide etching are more often used.
Deep reactive-ion etching. Deep reactive-ion etching (DRIE) is a special subclass of reactive-ion etching (RIE). It enables highly anisotropic etch process used to create deep penetration, steep-sided holes and trenches in wafers /substrates, typically with high aspect ratios. It was developed for microelectromechanical systems (MEMS), which ...
Isotropy. In physics and geometry, isotropy (from Ancient Greek ἴσος (ísos) 'equal' and τρόπος (trópos) 'turn, way') is uniformity in all orientations. Precise definitions depend on the subject area. Exceptions, or inequalities, are frequently indicated by the prefix a- or an-, hence anisotropy.
This is known as anisotropic etching and one of the most common examples is the etching of silicon in KOH (potassium hydroxide), where Si <111> planes etch approximately 100 times slower than other planes (crystallographic orientations). Therefore, etching a rectangular hole in a (100)-Si wafer results in a pyramid shaped etch pit with 54.7 ...
A plasma etcher, or etching tool, is a tool used in the production of semiconductor devices. A plasma etcher produces a plasma from a process gas, typically oxygen or a fluorine -bearing gas, using a high frequency electric field, typically 13.56 MHz. A silicon wafer is placed in the plasma etcher, and the air is evacuated from the process ...
Wet etching was widely used in the 1960s and 1970s, [144] [145] but it was replaced by dry etching/plasma etching starting at the 10 micron to 3 micron nodes. [146] [147] This is because wet etching makes undercuts (etching under mask layers or resist layers with patterns). [148] [149] [150] Dry etching has become the dominant etching technique ...