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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, and every wafer undergoes many etching steps before it is complete.
If the etch is intended to make a cavity in a material, the depth of the cavity may be controlled approximately using the etching time and the known etch rate. More often, though, etching must entirely remove the top layer of a multilayer structure, without damaging the underlying or masking layers. The etching system's ability to do this depends on the ratio of etch rates in the two materials (selectivity).
Some etches undercut the masking layer and form cavities with sloping sidewalls. The distance of undercutting is called bias. Etchants with large bias are called isotropic.
Modern VLSI processes avoid wet etching, and use plasma etching instead. Plasma systems can operate in several modes by adjusting the parameters of the plasma. Ordinary plasma etching operates between 0.1 and 5 Torr. (This unit of pressure, commonly used in vacuum engineering, equals approximately 133.3 pascals) The plasma produces energetic free radicals, neutrally charged, that react at the surface of the wafer. Since neutral particles attack the wafer from all angles, this process is isotropic.
The source gas for the plasma usually contains small molecules rich in chlorine or fluorine. For instance, carbon tetrachloride (CCl4) etches silicon and aluminium, and trifluoromethane etches silicon dioxide and silicon nitride. A plasma containing oxygen is used to oxidize ("ash") photoresist and facilitate its removal.
Allwin21 Corp focuses on the following main Etcher equipments.
Matrix303
Matrix403
Gasonics AE2001
Gasonics PEP3510
Tegal901e
Tegal903e
AW Control Software provides the unique upgrade system for Matrix, Gasonics, Tegal, Series. Advantage of upgraded system include:
Integrated process control system
Real time graphics display
Real time process data acquisition, display, and analysis
Programmed comprehensive calibration and diagnostic functions
Better performance and maintenance than the original systems
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