Process for the production of microelectromechanical systems

#This application is a U.S. national stage application under 35 U.S.C. §371 of International Application No. PCT/EP2008/067623 file Dec. 16, 2008, which claims priority to European Patent Application No. 07150296.7 file Dec. 21, 2007, this whole content of this application being incorporated herein by reference for all purposes.

#The present invention relates to the etching of circuit patterns on semiconductor wafer structures in the fabrication of integrated circuits, specifically it relates to the etching of deep trenches in structures in the fabrication of microelectromechanical systems (“MEMS”).

#MEMS concerns the technology of very small items, e.g. machines, generally ranging in the size from a micrometer to a millimeter. The potential of very small machines was appreciated long before the technology existed. Common applications include inkjet printers operating with piezoelectrics or thermal bubble ejection, accelerometers in cars, e.g. for airbag deployment in collisions, gyroscopes, silicon pressure sensors e.g. for monitoring car tires or blood pressure, optical switching technology or bio-MEMS applications in medical and health-related technologies. Microelectronic circuits process the information gathered by sensors from the environment through measuring mechanical, thermal, biological, chemical, optical or magnetic phenomena.

#General procedure: the different constituents are passed in gaseous form from respective storing bottles to a stainless steel container stored therein in gaseous form. By controlling the volume during storing the respective gases, gas mixtures comprising the appropriate amounts of gases given in table 1 are prepared.

#TABLE 1 Etching gas mixtures (amounts given in % by volume) Example F2 COF2 N2 Ar O2 1.1 20 70 10 — 1.2 — 70 — 20 10 1.3 5 65 20 10 — 1.4* 5 55 20 10 *Elemental fluorine and nitrogen are added as 1:4 v/v mixture.

#TABLE 2 Passivating gas mixtures Example C4F6 Ar H2 CHF3 1.5 60 40 — — 1.6 50 40 — 10 1.7 50 40 10 — 1.8 40 40 10 10 (amounts given in % by volume)