Process for the production of microelectromechanical systems
| Title: | Process for the production of microelectromechanical systems |
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| Patent Number: | 8,524,112 |
| Publication Date: | September 03, 2013 |
| Appl. No: | 12/808718 |
| Application Filed: | December 16, 2008 |
| Abstract: | Elemental fluorine and carbonyl fluoride are suitable etchants for producing microelectromechanical devices (“MEMS”). They are preferably applied as mixtures with nitrogen and argon. If applied in Bosch-type process, C4F6 is a highly suitable passivating gas. |
| Inventors: | Riva, Marcello (Hannover, DE) |
| Assignees: | Solvay Fluor GmbH (Hannover, DE) |
| Claim: | 1. A method of producing a microelectromechanical system (“MEMS”) from a structure comprising a step wherein the structure is etched applying an etching gas, wherein said etching gas is a mixture consisting of elemental fluorine, nitrogen, argon, and optionally oxygen, said mixture containing equal to or more than 10% by volume of elemental fluorine, equal to or less than 25% by volume of elemental fluorine, equal to or more than 5% by volume of argon, equal to or less than 15% by volume of argon, equal to or more than 65% by volume of nitrogen, equal to or less than 80% by volume of nitrogen, and optionally between 2 and 15% by volume of oxygen, the contents adding up to 100% by volume. |
| Claim: | 2. The method according to claim 1 , wherein consecutively to etching, passivation of at least a part of an etched surface of the structure is provided. |
| Claim: | 3. The method according to claim 2 , wherein said passivation is carried out with a passivating agent selected from organic compounds providing, in a plasma, a fluoropolymer. |
| Claim: | 4. The method according to claim 3 , wherein the passivating agent is a passivating gas selected from the group consisting of c-C 4 F 6 , c-C 5 F 8 , CH 2 F 2 , CHF 3 , CF 4 , C 2 F 6 , C 3 F 8 , C 2 F 4 , C 4 F 6 , c-C 6 F 6 , CF 3 I, and C 4 F 8 . |
| Claim: | 5. The method according to claim 1 , wherein said structure is a silicon wafer. |
| Claim: | 6. The method according to claim 1 , wherein a passivating gas comprising C 4 F 6 is applied for providing passivation in a passivating step, and wherein the etching step and passivating step are performed consecutively after each other. |
| Claim: | 7. A mixture, comprising carbonyl fluoride, a passivating gas, and argon, and optionally further comprising a compound selected from the group consisting of nitrogen, hydrogen, and a hydrogen-releasing gas, wherein the content of carbonyl fluoride is equal to or greater than 15% by volume and equal to or lower than 60% by volume; wherein the content of the passivating agent is equal to or greater than 10% by volume and equal to or lower than 50% by volume; wherein the content of argon is equal to or greater than 20% by volume and equal to or lower than 50% by volume; wherein, when nitrogen is comprised in the mixture, its content is in a range of from 1 to 10% by volume; and wherein, when hydrogen or the hydrogen-releasing gas is comprised in the mixture, its content is equal to or greater than 2% by volume and equal to or lower than 15% by volume. |
| Claim: | 8. The mixture according to claim 7 , further comprising nitrogen. |
| Claim: | 9. The mixture according to claim 7 , wherein the passivating gas is selected from the group consisting of c-C 4 F 6 , c-C 5 F 8 , CH 2 F 2 , CHF 3 , CF 4 , C 2 F 6 , C 3 F 8 , C 2 F 4 , C 4 F 6 , c-C 6 F 6 , CF 3 I, and C 4 F 8 . |
| Claim: | 10. A mixture consisting of elemental fluorine, nitrogen, argon, and optionally oxygen, said mixture containing equal to or more than 10% by volume of elemental fluorine, equal to or less than 25% by volume of elemental fluorine, equal to or more than 5% by volume of argon, equal to or less than 15% by volume of argon, equal to or more than 65% by volume of nitrogen, equal to or less than 80% by volume of nitrogen, and optionally between 2 and 15% by volume of oxygen, the contents adding up to 100% by volume. |
| Claim: | 11. The mixture according to claim 10 , being in liquid state. |
| Claim: | 12. The mixture according to claim 11 , being compressed in a container. |
| Claim: | 13. The mixture according to claim 10 , wherein the sum of elemental fluorine and argon is equal to or lower than 45% by volume and equal to or higher than 25% by volume. |
| Claim: | 14. The mixture according to claim 10 , wherein the content of elemental fluorine is in the range of from 18 to 22% by volume. |
| Claim: | 15. The mixture according to claim 7 , being in liquid state. |
| Claim: | 16. The mixture according to claim 11 , wherein the passivating gas is C 4 F 6 . |
| Claim: | 17. A method for producing a microelectromechanical system (“MEMS”) from a structure, said method comprising simultaneously etching and passivating the structure while applying the mixture according to claim 7 . |
| Claim: | 18. The mixture according to claim 7 , further comprising hydrogen or a hydrogen-releasing gas. |
| Current U.S. Class: | 252/791 |
| Patent References Cited: | 4784720 November 1988 Douglas 4805456 February 1989 Howe et al. 5047115 September 1991 Charlet et al. 5445712 August 1995 Yanagida 5445713 August 1995 Kunihisa et al. 5501893 March 1996 Laermer et al. 6015759 January 2000 Khan et al. 6203671 March 2001 Demmin 2001/0027702 October 2001 Hobbs et al. 2003/0189024 October 2003 Khan et al. 2005/0029221 February 2005 Chang et al. 2006/0108576 May 2006 Laermer et al. 2007/0056926 March 2007 Ko 2007/0187359 August 2007 Nakagawa et al. 2007/0232048 October 2007 Miyata et al. 0200951 December 1986 1498940 January 2005 1596419 November 2005 2290413 December 1995 10223614 August 1998 2003081919 March 2003 WO 94/14187 June 1994 WO 03/066515 August 2003 WO 2007/116033 October 2007 WO 2010/115734 October 2010 |
| Other References: | Hibert, Cyrille—“State of the art DRIE processing”, presentation at the Center of MicroNanoTechnology (CMI) annual review on May 18, 2004; accessed online on Feb. 28, 2012 at http://cmi.epfl.ch/etch/files/Talk—Cyrille—CMI2004.pdf ; 14 pgs. cited by applicant Arana, Leonel, R., et al—“Isotropic etching of silicon in fluorine gas for MEMS micromachining”, Journal of Micromechanics and Microengineering, 2007, vol. 17 (2) , pp. 384-392; 9 pgs. cited by applicant Bargon, J., et al—“Oxygen Containing Fluorocarbons as Gaseous Etching Compounds for Reactive Ion Etching”, 1978, IBM Technical Disclosure Bulletin, vol. 20 (8), p. 3295; 1 pg. cited by applicant Vittorio, Salvatore A.—“MicroElectroMechanical Systems (MEMS)”, Proquest, Released Oct. 2001; accessed online at http://www.csa.com/discoveryguides/mems/overview.php on Dec. 13, 2007 ; 7 pgs. cited by applicant Peccoud, L., et al—“New trends and limits in plasma etching”, 1987, Journal of Physics D: Applied Physics, vol. 20( 7) pp. 851-857; 7 pgs. cited by applicant U.S. Appl. No. 12/296,139, filed Oct. 6, 2008, Anja Pischtiak, et al. cited by applicant |
| Primary Examiner: | Deo, Duy |
| Attorney, Agent or Firm: | Ortego, Beatrice C. |
| Accession Number: | edspgr.08524112 |
| Database: | USPTO Patent Grants |
| Language: | English |
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