Ceramic element e.g. lid, for cooperating with part to e.g. form cavity for encapsulation device encapsulating microelectromechanical systems, has metal layer protected by intermetallic layer, which is covered by material part
HM 705,797 A2 Specification field of the invention l'invention relates to a method of manufacturing an encapsulation device for an electro-micromechanical (also known under the abbreviation the MEMS from English terms "micro-System") and, in particular, for a MEMS type quartz resonator. Background of the invention the electronic components having a MEMS are formed generally by a hermetically sealed housing in which is mounted the MEMS. The MEMS can be e.g. a piezoelectric resonator, such as a quartz resonator for connection to an oscillator circuit. Most of the small quartz resonators, which are for example used in electronic watches or electromechanical, are tuning fork type resonator. de such quartz resonators are usually enclosed vacuum in housings, in the case of generating low frequency signal provided by the oscillator circuit, or in an inert gas atmosphere. In addition, a portion of the cover can be transparent to a wavelength of a light beam determined to permit adjustment of the optical of the quartz resonator. generally, such resonators are mounted in housings such as ceramics which are relatively flat. These packages comprise a hollow main part of parallelepipedal shape inside which is mounted the resonator, and a rectangular cover attached to the main portion. to ensure sealing between the cover and the main portion, currently, use is made of a metal alloy seal eutectic gold and tin which is inserted between the two parts and the assembly is heated to finally sealing the housing under a controlled atmosphere. alloys are gold and tin have disadvantages to use materials inherently expensive and have a relatively low melting point, [...] to say about 278 °c. The latter feature limits the possible methods during or after the connection of the housing on its support for use as a circuit board, for example. It is understood indeed that any heat treatment greater than 280 °c carried out subsequently to the connection is only possible under an unsealing of the casing which, even partial, would lose the hermeticity of the device and thus the performance of the resonator. The element e.g. lid (4), has an element body that is intended for forming a metal layer (15) for metallization, where the element is partially covered by the metallization. The metallization comprises a coating for protection against gold oxidation. The metal layer is protected by an intermetallic layer (19), which is covered by a non-diffused material part (12'), where melting point of material e.g. indium and tin, is lower than 250 degrees Celsius. The metal layer comprises a fixing layer (13) fixing against the body. Independent claims are also included for the following: (1) a method for manufacturing an element (2) an encapsulation device (3) a method for manufacturing an encapsulation device. 1. element (2, 4, 44, 64) arranged to cooperate with another part (4, 2) to form an encapsulation device (3) of a component (5) having the element (2, 4, 44, 64) at least partially coated with a metallic coating (11, 9, 49, 69) characterized in that said metallic coating comprises at least one layer (15, 16, 55, 64) protected by a metal intermetallic (19, 59, 79) which is covered by a section (12 ', 52', 72') unscattered material whose melting point is lower than 250 °c. 2. element (2, 4, 44, 64) according to the preceding claim, characterized in that the member is a cover (4, 44, 64) for closing said encapsulation device (3). 3. element (2, 4, 44, 64) according to claim 1, characterized in that the element is a main portion (2) for forming a cavity (10) of the device (3) encapsulating. 4. element (2, 4, 44, 64) according to one of the preceding claims, characterized in that the element (2, 4, 44, 64) is formed from a ceramic or metal. 5. element (2, 4, 44, 64) according to one of the preceding claims, characterized in that said at least one layer (15, 16, 55, 75) metal layer includes nickel and/or copper and/or gold. 6. element (2, 4, 44, 64) according to one of claims 1 to 4, characterized in that said at least one metal layer is formed by the body of the element (64). 7. element (2, 4, 44, 64) according to one of the preceding claims, characterized in that said at least one metal layer (15, 16) further comprises a layer (13, 14) engaging against said element body (2, 4). 8. element (2, 4, 44, 64) according to the preceding claim, characterized in that the layer (13, 14) hooking includes molybdenum and/or tungsten and/or titanium and/or chromium. 9. element (2, 4, 44, 64) according to one of the preceding claims, characterized in that the intermetallic (19, 59, 79) comprises gold. 10. Element (2, 4, 44, 64) according to one of the preceding claims, characterized in that said material whose melting point is lower than 250 °c is indium. HM 705,797 A2 1, 1. Element (2, 4, 44, 64) according to one of claims 1 to 9, characterized in that said material whose melting point is lower than 250 °c is tin. 12. method (24, 26) for producing a (2, 4, 44, 64) arranged to cooperate with another part (4, 2) to form an encapsulation device of (3) of a component (5) comprising the following steps: a) forming the member (2, 4, 44, 64); and b) depositing a metalization (9, 11, 49, 69) comprising at least one layer (15, 16, 55) protected by a coating of metal (17, 18, 57, 75); characterized in that it further comprises the following steps: c) depositing a layer (12, 52, 72) of a material whose melting point is lower than 250 °c on the coating (17, 18, 57, 75); d) partially diffuse material whose melting point is lower than 250 °c in the coating (17, 18, 57, 75) to fully convert the coating (17, 18, 57, 75) in a intermetallic and leaving a portion (12 ', 52', 72') non-diffuse material whose melting point is lower than 250 °c. 13. Method (24, 26) according to the preceding claim, characterized in that the element (2, 4, 44, 64) is formed from a ceramic or metal. 14. Method (24, 26) according to claim 12 or 13, characterized in that said at least one layer (15, 16, 55) metal layer includes nickel and/or copper and/or gold. 15. Method (24, 26) according to claim 12 or 13, characterized in that said at least one metal layer is formed by the body of the element (64). 16. Method (24, 26) according to any of claims 12 to 15, characterized in that the method comprises, between step a) and step b), a step of depositing a layer (13, 14, 33, 34) for engaging said at least one layer (15, 16) of metal. 17. Method (24, 26) according to the preceding claim, characterized in that the layer (13, 14) hooking includes molybdenum and/or tungsten and/or titanium and/or chromium. 18. method (24, 26) according to any of claims 12 to 16, characterized in that the coating (17, 18, 57, 75) comprises gold. 1 9. (3) encapsulating device arranged to receive a component (5) comprising a housing (7) comprising a main portion (2) forming a cavity (10) which is sealed by a cap (4, 44, 64) with sealing means (6) characterized in that the sealing means (6) comprise an intermetallic (20, 40) formed by at least one metal (15, 16, 15 ', 16', 55, 64) with a material (12, 52, 72) whose melting point is lower than 250 °c to allow intermixing its liquid state with said at least one metal. 20. (3) encapsulation device according to the preceding claim, characterized in that the sealing means (6) comprise a second intermetallic (19, 19 ', 39, 39', 59, 79) adjacent said first (20, 40) intermetallic formed by at least one second metal (17, 18, 57, 75) with the material (12, 52, 72) whose melting point is lower than 250 °c. 21. (3) encapsulation device according to the preceding claim, characterized in that said at least one second metal (17, 18, 57, 75) comprises gold. 22. (3) encapsulation device according to claim 20 or 21, characterized in that the sealing means (6) comprise a third intermetallic (40) generally identical to the first intermetallic, the first and third intermetallic being located at each side of the second intermetallic (39'). 23. (3) encapsulation device according to one of claims 19 to 22, characterized in that the sealing means (6) comprise at least one primer layer (13, 14, 33, 34) against the housing (7). 24. (3) encapsulation device according to one of claims 19 to 23, characterized in that the sealing means (6) comprise a layer of said at least one metal (15, 16, 15 ', 16', 55, 64) between the cover (4, 44, 64) and said intermetallic (20, 40) and between the main part (2) and said intermetallic (20, 40). 25. (3) encapsulation device according to one of claims 19 to 23, characterized in that the sealing means (6) comprise a layer of said at least one metal (15, 16, 15 ', 16', 44) between the main part (2) and said intermetallic (20, 40) and in the cover (64). 26. (3) encapsulation device according to one of claims 19 to 25, characterized in that said material whose melting point is lower than 250 °c is indium. 27. (3) encapsulation device according to one of claims 19 to 25, characterized in that said material whose melting point is lower than 250 °c is tin. 28. (3) encapsulation device according to one of claims 19 to 27, characterized in that said at least one metal (15, 16, 15 ', 16', 55, 64) includes nickel and/or copper and/or gold. HM 705,797 A2 29. (3) encapsulation device according to one of claims 19 to characterized in that the housing (7) is formed of a ceramic and/or metal. 30. (3) encapsulation device according to one of claims 19 to characterized in that the cavity (10) is under vacuum or in a controlled atmosphere. 31. (21) a method of manufacturing a device (3) encapsulating a component (5) characterized in that it comprises the following steps: e) (5) form said component; F.) making a main portion (2) having a first metalization (1, 1) and forming a cavity (10), and a cover (4, 44, 64) including a second metal plating (9, 49, 69), the main part (2) or cover (4, 44, 64) being realized according to the method (24, 26) according to any of claims 12 to 17; grams) (25) for mounting the component (5) in the cavity (10); and H) assembling (27) the portion (12 ', 52', 72 ') non-diffuse material whose melting point is lower than 250 °c during step d) of the main part (2) or cover (4, 44, 64) against respectively the metalization (9, 11) of the cover (4, 44, 64) or the main part (2); I-) diffuse completely encircle the (29) (12', 52 ', 72') non-diffuse material whose melting point is lower than 250 °c in said metallization (11, 9, 49, 69) adjacent to completely transform the material whose melting point is lower than 250 °c in a second intermetallic (20) adapted to seal said component in the encapsulation device (3). 32. (21) the method according to the preceding claim, characterized in that it comprises, between step f) and step g), the step of depositing a layer (18, 17, 57, 75) protection to protect said metallization formed not covered by the part (12 ', 52', 72') non-scattered. 33. (21) a method according to claim 31 or 32, characterized in that the main part (2) and the cover (4, 44, 64) are formed of ceramic and/or metal. 34. (21) a method according to one of claims 31 to 33, characterized in that step I) is carried out under vacuum or in a controlled atmosphere. 35. Method (21, 24, 26) according to any of claims 12 to 17 and 31 to 34, characterized in that said component (5) is a quartz tuning fork resonator. 36. Method (21, 24, 26) according to any of claims 12 to 17 and 31 to 35, characterized in that the material whose melting point is lower than 250 °c is indium. 37. method (21, 24, 26) according to any of claims 12 to 17 and 31 to 35, characterized in that the material whose melting point is lower than 250 °c is tin.
