Advanced Silicon Etching (ASE) is a

deep reactive-ion etching Deep reactive-ion etching (DRIE) is a special subclass of reactive-ion etching (RIE). It enables highly anisotropy, anisotropic etching (microfab), etch process used to create deep penetration, steep-sided holes and trenches in wafer (semiconducto ...

(DRIE) technique to etch deep and high aspect ratio structures in silicon. ASE was created b
Surface Technology Systems Plc
(STS) in 1994 in the UK. STS has continued to develop this process with faster etch rates. STS developed and first implemented the switched process, originally invented by Dr. Larmer in Bosch, Stuttgart. ASE consists in combining the faster etch rates achieved in an

isotropic In physics and geometry, isotropy () is uniformity in all orientations. Precise definitions depend on the subject area. Exceptions, or inequalities, are frequently indicated by the prefix ' or ', hence '' anisotropy''. ''Anisotropy'' is also ...

Si etch (usually making use of an SF₆ plasma) with a deposition or passivation process (usually utilising a C₄F₈ plasma condensation process) by alternating the two process steps. This approach achieves the fastest etch rates while maintaining the ability to etch anisotropically, typically vertically in Microelectromechanical Systems (

microelectromechanical systems MEMS (micro-electromechanical systems) is the technology of microscopic devices incorporating both electronic and moving parts. MEMS are made up of components between 1 and 100 micrometres in size (i.e., 0.001 to 0.1 mm), and MEMS devices ...

(MEMS)) applications. The ASE HRM claims to be an improvement on previous generations of ICP design, now incorporating a decoupled plasma source (patent pending). The decoupled source generates high-density plasma which is allowed to diffuse into a separate process chamber. Using a specialized chamber design, the excess ions (which negatively affect process control) are reduced, leaving a uniform distribution of fluorine free-radicals at a higher density than that available from the conventional ICP sources. The higher fluorine free-radical density facilitates increased etch rates, typically over three times the etch rates achieved with the original process.

Notes

References

* {{Citation , last = Hopkins , first = J , title = Developments in Si and SiO₂ Etching for MEMS-based Optical Applications (2004) , url=http://www.stsystems.com/pages/process_content.asp?menuID=33&subID=80&menuTitle=Technical%20Papers&mainMenuTitle=Publications , accessdate = 2008-04-01 , archiveurl = https://web.archive.org/web/20070702162101/http://www.stsystems.com/pages/process_content.asp?menuID=33&subID=80&menuTitle=Technical+Papers&mainMenuTitle=Publications , archivedate = July 2, 2007.

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Further reading