EP2321216A2

EP2321216A2 - Method and device for encapsulating microstructures

Info

Publication number: EP2321216A2
Application number: EP09740426A
Authority: EP
Inventors: Sébastien Brault; Elisabeth Dufour-Gergam; Martial Desgeorges
Original assignee: KFM Technology SRL
Current assignee: KFM Technology SRL
Priority date: 2008-08-01
Filing date: 2009-07-31
Publication date: 2011-05-18
Also published as: JP2011529798A; FR2934580B1; WO2010012966A2; US20110165365A1; WO2010012966A3; FR2934580A1; US8617413B2

Abstract

The present invention relates to a method for encapsulating structures (11) (typically MEMS structures) supported by a carrier substrate (12) (typically made of glass or silicon), which method comprises: application, on the carrier substrate (12), of at least one cover (7) supported by a mould (1, 2, 6), the mould comprising a catching layer (6), each cover (7) being in contact with the catching layer (6); then fastening of at least one cover (7) onto the carrier substrate (12); and then separation of the mould (1, 2, 6) from the at least one cover (7). The catching layer (6) comprises a fluoropolymer. Preferably, the mould (1, 2, 6) is separated from the at least one cover (7) by mechanical means, by pulling the mould (1, 2, 6) away from the at least one cover (7). Thus, the mould (1) can be reused, which considerably simplifies encapsulating operations carried out on an industrial scale.

Description

"Method and device for encapsulating microstructures"

Technical area

The present invention relates to a method and a device for individually or collectively encapsulating structures carried by a substrate. It also relates to an encapsulation mold for such a method or device, and a method of manufacturing such a mold.

The field of the invention is more particularly but not limited to that of the encapsulation of microsystems on a glass or silicon substrate.

State of the art

In all fields, the packaging stage represents the final step of manufacturing a product. The packaging of microelectromechanical systems (or MEMS for "Micro Electro Mechanical Systems") is complex because the MEMS include mechanical parts generally deformable or mobile very sensitive to liquids and generally to their environment.

In many cases, the microsystems must be protected from the external environment in a humidity and gas-tight cavity in order to limit their aging and increase their reliability.

The creation of this cavity for the encapsulation of the microsystem is also called "Packaging". This packaging step has become as important today as the microsystems manufacturing process.

In the 1980s, a new approach was developed: Wafer-Level Packaging (WLP) enables collective and simultaneous encapsulation of all microsystems present on a carrier substrate.

The ultimate goal of MEMS encapsulation in a cavity is to protect them from the external environment to the cavity and to ensure the stability and reliability of their performance. To achieve this goal encapsulation must generally provide all or part of the following functions:

• mechanical protection of MEMS from scratches, shocks and vibrations that may occur during their testing, handling, transportation or use;

• chemical protection of MEMS against corrosion, contamination and humidity thanks to the stability and inertia of the internal cavity environment;

• a passage of connections (usually electrical connections) between the microsystems and the external environment to the cavity;

• a thermal management of the devices, ie in particular a protection to the heat).

A disadvantage of existing encapsulation processes is that they are very complex and cumbersome to implement. In particular, each encapsulation generally requires the manufacture of a mold to be completely dissolved during encapsulation.

The object of the present invention is to provide a method and a device for encapsulation simpler and / or more effective than those of the state of the art.

Presentation of the invention

This objective is achieved with a method of encapsulation of at least one structure carried by a carrier substrate, comprising:

an application on the carrier substrate of at least one cover carried by a mold, the mold comprising a hooked layer, each cover being in contact with the hooked layer, and

a fixation of the at least one cover on the carrier substrate, then

- A separation of the mold and the at least one cover, characterized in that the hook layer is made from a fluoropolymer and therefore comprises this fluoropolymer.

By fluoropolymer is meant throughout this document a polymer comprising fluorine atoms. According to the invention, the fluorinated polymer preferably comprises at least one carbon chain and along this chain several CF type bonds between a carbon atom C and a fluorine atom F, as is the case in a fluorocarbon polymer. The fluoropolymer preferably comprises but not limited to Teflon. The fluoropolymer preferably comprises a fluorocarbon polymer such as: PTFE-type Teflon, also called polytetrafluoroethylene,

- Teflon type FEP, also called fluorinated ethylene-propylene,

PFA type Teflon, also called perfluoroalkoxy,

PVDF, also called polyfluorovinylidene,

ETFE, also called modified copolymer of ethylene and tetrafluoroethylene, and

- ECTFE, also called ethylene / chlorotri-fluoroethylene.

In a first embodiment of the encapsulation method according to the invention, it is possible to separate the mold and the at least one cover mechanically, by tearing the mold from at least one cover. The mold preferably comprises a mold substrate in contact with the hook layer, and the breaking force required to separate the mold substrate and the hook layer is preferably greater than the breaking force required to separate the mold layer. layer of hung and the at least one hood.

In a second embodiment of the encapsulation process according to the invention, the mold can be separated from the at least one cover chemically, by dissolving the hooked layer. For example, the bonding layer can be dissolved in an acid bath or in a solvent bath, for example in a nitric acid bath.

In the encapsulation process according to the invention, the at least one cover is preferably fixed on the carrier substrate by means of a polymer seal or a eutectic seal located between the at least one cover and the substrate. carrier, or by means of a thermo-compression welding. When applying the at least one cover, the seal may be structured at at least one connection passage connected to the at least one structure. In addition, the at least one hood may be perforated, and may include one or more holes of various sizes and shapes. These holes are particularly useful in the case where the cover encapsulates an optical structure such as a light detector or an acoustic structure such as a microphone.

The mold preferably comprises silicon atoms. Thus, the mold can adhere with the fluoropolymer due to its content of silicon, especially via Si-C bonds between silicon atoms of the mold and carbon atoms of the fluorocarbon polymer.

Each cap may comprise a metal layer in contact with the fluoropolymer.

The invention further relates to an encapsulated structure obtained by the encapsulation method according to the invention.

According to yet another aspect of the invention, there is provided a device for encapsulating at least one structure carried by a carrier substrate, implementing a method according to the invention, and comprising: a mold comprising a layer of hooked and carrying at least one cover so that each cover is in contact with the hooked layer,

means for applying, on the carrier substrate, the at least one cover carried by the mold,

means for fixing on the carrier substrate the at least one cover applied to the carrier substrate, means for separating the mold and the at least one cover fixed on the carrier substrate, characterized in that the hooking layer comprises a fluorinated polymer.

The fluoropolymer preferably comprises a fluorocarbon polymer, and more specifically preferably polytetrafluoroethylene.

In a first embodiment of the device according to the invention, the separation means may comprise means for mechanically separating the mold and the at least one cover, arranged to tear the mold from at least one cover. The mold can then comprise a mold substrate in contact with the hook layer, and the breaking force needed to separate the mold substrate and the hook layer is preferably larger than the breaking force needed to separate the mold layer. layer of hung and the at least one hood.

In a second embodiment of the device according to the invention, the separation means may comprise means for separating chemically the mold and the at least one cover, arranged to dissolve the layer of hooked. The chemical separation means may for example comprise an acid bath or a solvent bath, in particular a nitric acid bath.

The fixing means may comprise means for welding a polymer seal or a eutectic seal located between the at least one cap and the carrier substrate, or thermo-compression welding means. The seal may comprise at least one structured part for at least one passage of a connection connected to the at least one structure.

In addition, the at least one hood can be holed as previously described.

The mold may include silicon atoms.

Each cap may comprise a metal layer in contact with the fluoropolymer.

The invention also relates to an encapsulation mold for an encapsulation device according to the invention and for an encapsulation process according to the invention, said mold comprising: a mold substrate comprising at least one mold cavity; hook layer deposited on one side of the mold substrate carrying the at least one mold cavity, characterized in that the hook layer comprises a fluoropolymer.

The mold substrate may comprise silicon atoms.

The mold according to the invention can carry, at each mold cavity, a cover on the hooked layer. Each cover preferably comprises a metal layer in contact with the fluoropolymer. The breaking force required to separate the mold substrate and the hook layer is preferably greater than the breaking force required to separate the hook layer and the at least one cover. At least one of the hoods can be holed as previously described. In general, the invention relates to a mold obtained by a method of manufacturing a mold according to the invention.

Indeed, the invention also relates to a method of manufacturing an encapsulation mold according to the invention, comprising: an etching in a mold substrate, for forming at least one mold cavity, - a deposit of a layer hooked on one side of the mold substrate carrying the at least one mold cavity, characterized in that the hook layer comprises a fluoropolymer.

After the deposition of the hook layer, the mold substrate may comprise silicon atoms.

The mold manufacturing method according to the invention may further comprise a deposit, on the hook layer, of a cover at each mold cavity. Each cap may comprise a metal layer in contact with the fluoropolymer. The breaking force required to separate the mold substrate and the hook layer is preferably greater than the breaking force required to separate the hook layer and the at least one cover. At least one of the hoods can be holed as previously described.

The deposition of the hook layer preferably comprises an exposure of the mold substrate to a plasma of C ₄ F ₈ (this compound comprising four carbon atoms for eight fluorine atoms) such as octafluorobutene, perfluorobutene, hexafluorobutene, octafluorocyclobutane or the like.

Description of the Figures and Embodiments

Other advantages and particularities of the invention will appear on reading the detailed description of implementations and non-limiting embodiments, and the following appended drawings: FIG. 1 is a sectional sectional view of a mold according to the invention for an encapsulation device according to the invention, FIG. 2 is a three quarter view of the mold of FIG. 1,

FIG. 3 is a schematic view of a first preferred embodiment of an encapsulation device according to the invention, comprising the mold of FIGS. 1 and 2,

FIGS. 4 to 6 illustrate a mold, covers, and a carrier substrate of the device of FIG. 3 for different stages of an encapsulation process according to the invention.

Firstly, with reference to FIGS. 1 and 2, a mold 1 according to the invention for a device and encapsulation method according to the invention, and a manufacturing method according to the invention for manufacturing such a mold, will be described first. 1.

This manufacturing method comprises a chemical etching of a mold substrate 2 initially having a plate shape with parallel faces 4, 5. This mold substrate 2 is etched to form at least one mold cavity 3 on one of these parallel faces. 5. The mold substrate 2 is typically a glass or silicon wafer

This etching is carried out by a typical etching process in the field of lithography, and comprises for example a drawing of a pattern on the face 5 of the mold substrate 2 with the aid of a mask. Thus, the engraving of the mold is carried out:

- Wet (for example using an etching solution of KOH, EDP, TMAH ...), and in this case the areas not protected by the mask of Si ₃ N ₄ or SiO ₂ are etched, or

by dry seeing (for example of the "DRIE" type), and in this case the mask may be a photosensitive resin, an SiO ₂ mask, or an aluminum layer.

After this etching, a hook layer 6 is deposited on the face 5 of the mold substrate 2 carrying the at least one mold cavity 3. The hook layer 6 is made from a fluoropolymer and therefore comprises this fluorinated polymer. By fluoropolymer is meant a polymer comprising fluorine atoms. This fluorinated polymer here comprises a carbon chain and along this chain several CF type bonds between a carbon atom C and a fluorine atom F. This layer of hook is represented in dashed lines on the sectional views of Figures 1 and 3 to 6, and is shown in a layer filled with small dots in Figure 2. The fluoropolymer comprises a fluorocarbon polymer, and more specifically includes polytetrafluoroethylene (or "PTFE"). ) of general chemical formula:

or :

n is an integer, typically between 1 and an almost infinite number equal to several thousand, several million or more, and

the groups R 1 and R ₂ for example comprise carbon atoms C, oxygen O, fluorine F and / or other and therefore comprise, for example, CF, CH ₃ , CF ₃ or other groups.

Deposition of the bonding layer comprises exposing the mold substrate 2 to a C ₄ F ₈ plasma in a reactive ion etching (RIE) frame ("Reactive Ion Etching") or in a deep reactive ion etching frame "DRIE"("Deep Reactive Ion Etching").

The thickness of this hooked layer is between a few nanometers and a few micrometers. The contact angle between a drop of deionized water and this hook layer 6 has a value of between 100 ° and 115 °.

Then, a thick resin lithography 17 is performed on the mold 1, more precisely on the hook layer 6. The resin 17 is shown only in Figure 1, and not in Figure 2.

Then, several covers 7 are deposited on the mold 1, more precisely on the hooking layer 6, a cover 7 being deposited at each mold cavity 3, so that each cover 7 takes the form of a cavity of mold 3 and thus has a shape of hood cavity 8. Each cover 7 has the shape of a substantially constant thickness plate forming a hood cavity 8. The deposit of covers 7 comprises a stack of films. These films are metal films such as nickel, copper, and / or titanium films. Concretely, we deposit on the substrate of mold 2 successively and on top of each other a titanium thin film using an evaporator or a sprayer, then a thin copper film using an evaporator or a sprayer, then a thick film of nickel by electrochemical bath. The thick nickel film is thus oriented towards the inside (that is to say the concave side) of each hood cavity 8 with respect to the other films, and constitutes the mass of each hood, that is to say the majority of the material of each hood.

The pattern of the resin 17 deposited during the thick resin lithography allows to define the shape and size of each cover 7, and to separate the covers 7 between them. The pattern of the resin 17 is not necessarily continuous: in particular, the pattern of the resin 17 may comprise isolated portions 27 located in at least one of the mold cavities 3.

The hook layer 6 is a non-adherent layer vis-à-vis the covers. In other words, the adhesion between the mold substrate 2 and the hook layer 6 is greater than the adhesion between the hook layer 6 and the covers 7. The mold substrate 2 made of glass or silicon comprises silicon atoms which are in direct contact with mainly the carbon atoms of the fluorocarbon polymer 6. Thus, the mold can adhere with the fluoropolymer due to its content of silicon atoms, especially via Si-C bonds between silicon atoms of the mold and the carbon atoms of the fluorocarbon polymer. Each cap 7 comprises a titanium metal layer which is in direct contact with mainly fluorine atoms of the fluorocarbon polymer. The breaking force necessary to separate the mold substrate 2 and the hook layer 6 is greater than the breaking force required to separate the hook layer 6 and each cover 7. This phenomenon is even more accentuated by the fact that the use of C ₄ F ₈ plasma to make the hook layer 6.

Then, the resin 17 is removed for example by dissolving it. Figure 2 illustrates the mold 1 after dissolution of the resin 17. After dissolution of the insulated portions 27, at least one mold is obtained with holes 37 through which the hook layer 6 is exposed.

Finally, for each cover 7, a seal 9 is deposited: which is situated on the cover 7 considered, on the opposite side of this cover 7 with respect to the hooking layer 6, and

- which surrounds the cavity 8 of the cover considered 7.

In a variant, the joints 9 are eutectic joints, comprising an alloy whose melting point is less than that of each of the elements constituting it. This alloy consists for example of an alloy of gold and silicon.

In another variant, the seals 9 comprise a polymer gasket comprising, for example, benzo-cyclo-butene (BCB) or an epoxy resin, in particular an SU8-type resin.

The encapsulation mold 1 resulting from this manufacturing process is illustrated in FIGS. 1 and 2, and comprises:

the mold substrate 2 made of glass or silicon, comprising a plurality of mold cavities 3,

- The hook layer 6 deposited on the face 5 of the mold substrate 2 carrying the mold cavities, the hook layer comprising a fluoropolymer comprising polytetrafluoroethylene.

This mold 1 is common to several covers 7. In fact, the mold 1 carries a cover 7 on the hook layer 6 at each mold cavity 3, so that each cover 7 is in direct contact with the protective layer. hung 6 and is connected to the mold 1 via the hooked layer. The covers 7 are separated, that is to say that they are not connected directly to each other, but only via the mold 1.

Finally, this mold carries for each cover 7 the seal 9 described above.

Note that in Figures 1 to 6, the mold 1 comprises only two mold cavities 8 and can carry only two covers 7. It will be understood that this representation is intended only to simplify and lighten these figures, the mold 1 typically comprising several tens, hundreds, thousands or more of mold cavity 8 so that it is arranged to carry as many covers 7.

With reference to FIGS. 3 to 6, a first preferred embodiment of an encapsulation device 10 according to the invention implementing a first preferred embodiment of the invention will now be described. encapsulation method according to the invention. FIG. 3 is a schematic view of the device 10, and FIGS. 4 to 6 are enlargements of a part of this device 10 illustrating the relative positions of the mold 1, the covers 7, and the carrier substrate 12 for different stages of an encapsulation process according to the invention.

The device 10 comprises the mold 1 already described with reference to FIGS. 1 and 2, which comprises the tie layer 6 made of polytetrafluoroethylene and which carries the covers 7 so that each cap is connected to the common mold via the diaper In addition, the device 10 comprises: means 13 for holding a carrier substrate 12, for example by pinching or sucking the carrier substrate 12, said carrier substrate bearing structures 11,

a motorized stage 14 arranged to move along three orthogonal axes X, Y, Z the carrier substrate held by the holding means 13,

means 15 for holding the mold 1, for example by pinching or sucking the mold 1, and

- A motorized plate 16 arranged to move along the three orthogonal axes X, Y, Z the mold 1 maintained by the holding means 15.

The carrier substrate 12 is typically a glass or silicon wafer. Each structure 11 is a microstructure, more precisely a microsystem such as an electromechanical microsystem or MEMS ("Micro Electro Mechanical Systems"). The MEMS 11 comprise, for example, a sensor, an actuator, or a "freed" MEMS (that is to say comprising a movable, disconnected or vibrating part) such as a resonator.

Before applying on the carrier substrate 12 the covers 7 carried by the mold 1, the good alignment of the mold 1 and the carrier substrate 12 in a plane defined by the X and Y axes is controlled by an alignment control device which is preferably independent of the encapsulation device according to the invention, but which in certain variants may be part of it. The mold 1 as the carrier substrate 12 comprise optical markers such as alignment crosses. The alignment check is controlled by alignment cross recognition software, these software collaborating with means for moving the carrier substrate 12 relative to the covers 7 carried by the mold 1, or this control of the alignment is performed manually by a user.

It is subsequently considered that the Z axis is substantially perpendicular to the mold 1 and the carrier substrate 12 and connects the mold 1 to the carrier substrate 12. In the device according to the invention, the plates 14 and 16 are arranged to approach the mold 1 in the direction of the carrier substrate 12 along the Z axis as illustrated in FIG. 4, until the caps 7 carried by the mold 1 are applied to the carrier substrate 12. Thus, thanks to these plates 14, 16, it is applied to the carrier substrate 12 the covers 7 carried by the mold by maintaining a certain pressure of the mold 1 and covers 7 on the carrier substrate 12. This application is illustrated in Figure 5. The plates 14, 16 are micrometric plates having accuracies of the order of one micron. Thanks to these plates, the covers 7 are applied on the carrier substrate 12 so that the concave face of each mold cavity 3 and each hood cavity 8 is oriented towards the carrier substrate 12 so as to cover, encapsulate and protect the least one of the structures 11. In other words, each cover 7 is applied to the carrier substrate 12 so that each structure 11 is encapsulated and protected in a cavity 8.

The device 10 further comprises means for fixing the covers 7 on the carrier substrate when these covers 7 are applied to the carrier substrate. The fixing means comprise a source of emission 18. During the application of the covers 7 on the carrier substrate 12 illustrated in FIG. 5, the covers 7 are thus fixed on the carrier substrate 12 by means of the seals 9 and the source. 18. The attachment thus comprises a seam weld 9 made at low temperature and at low pressure, so as not to affect the performance of the microsystems 11.

In the variant where the seals are eutectic seals, the source 18 emits heat to melt the seals 9 so as to weld the covers 7 to the carrier substrate 12. The advantages of the eutectic seals are a moderate welding temperature (typically around 300 °), a very good adhesion and the possibility of making cavities 8 encapsulant the structures 11 under vacuum.

In the preferred embodiment where the seals are polymer seals, the source 18 emits heat and / or ultraviolet radiation which transforms the seals 9 by passing them from a liquid or viscoelastic phase to a "solid" phase crosslinked or gelled by heating and / or exposure to UV radiation, so as to weld the covers 7 to the carrier substrate 12. The polymer joints 9 have a very good tolerance to the topography of the carrier substrate 12 and a low welding temperature range ranging from room temperature up to about 250 ⁰ C. Thus, a fixation via a polymer seal limits the risks of melting the layer of hanging 6. On the other hand, the polymer joints do not allow to make cavities under empty, the polymers are generally not sufficiently hermetic.

The seals 9 have in some places structured parts, so that when the covers 7 are applied to the carrier substrate 12, these seals 9 are structured at the level of electrical connection passages connected to the structures 11 and carried by the carrier substrate. . Each connection starts from a microstructure 11 to the outside of the cavity 8 encapsulating this microstructure 11. Apart from the structured parts, the joints 9 have a smooth outer surface and a constant thickness. At the structured portions, the seals 9 have the same thickness as at the unstructured portions but have a structured outer surface having, for example, a grid or embossing shape including grooves and depressions. When the seals 9 melt during attachment of the covers 7 to the carrier substrate 12, the lack of material at the embossing hollows compensates for the extra thickness due to the electrical connections.

Finally, the device 10 comprises means for separating the mold 1 and the covers 7, after these covers 7 have been fixed on the carrier substrate 12.

The separation means are arranged to mechanically separate the mold and each cover, by tearing each mold 7 from the mold 1. As shown in FIG. 6, the mold 1 and the covers 7 are separated by tearing off the covers 7, the mold 1 means motorized plates 16, 14 which draw in opposite directions along the axis Z on the one hand the mold 1 and other the covers 7 fixed to the carrier substrate 12, until mechanical rupture between the hook layer 6 and the covers 7. After the mechanical break, the polytetrafluoroethylene layer 6 remains on the mold substrate 2, and the covers 7 remain fixed on the carrier substrate 12 so as to form a substrate 12 carrying structures 11 encapsulated by covers 7.

Thus, the caps 7 are transferred from the mold 1 and to the carrier substrate 12, using a reusable mold 1. The mold 1 is reusable because the hooking layer 6 limits the adhesion between the mold 1 and the covers 7, and the hook layer 6 remains attached to the mold substrate 2. To reuse the mold 1, just deposit new covers 7 at each mold cavity 3, which greatly simplifies encapsulations made on an industrial scale.

In addition, the mold 1 comprising several cavities 3 and carrying several covers 7, it is noted that the encapsulation just described is a collective encapsulation, that is to say a simultaneous encapsulation in parallel of several structures 11 by several cavities 8, which has the advantage of being much faster than a series of individual encapsulation succeeding in time.

Finally, the encapsulation just described is compatible with the release of the microsystems 11 before encapsulation, because the carrier substrate 12 is not manipulated during the making of the covers 7. It is called liberation of a microsystem the fact of to make mobile or free of movement the parts of this microsystem to be mobile or free of movement for its proper functioning.

The device 10 finally comprises a bath 19 of fuming nitric acid concentrated to 99%, in which the encapsulated substrate 12 can be immersed by means of the motorized stage 14. Thus, by dipping the substrate 12 carrying the encapsulated structures 11, it is cleaned the covers of a few small residues of fluoropolymer that could remain accidentally on the hoods 7. The fluoropolymer residues can also be cleaned by means of an oxygen plasma.

We will now describe a second embodiment of encapsulation device according to the invention implementing a second encapsulation method embodiment of the invention, only for their difference from the first embodiments of device and method according to the invention described above. In particular, references 1 to 19 will not be described again.

In this second embodiment, the separation means comprise the bath 99% fuming nitric acid concentrated to 99%. Indeed, after fixing the covers 7 to the substrate 12, the bath 19 is immersed in the bath and by means of the plates 14 and 16 an assembly comprising the mold 1, the covers 7 carried by the mold 1 and fixed to the carrier substrate 12, and the carrier substrate 12. Thus, the mold 1 and the covers are separated chemically, by dissolving the hook layer 6 in the bath 19.

Of course, the invention is not limited to the examples that have just been described and many adjustments can be made to these examples without departing from the scope of the invention.

In particular, the seals 9 can be deposited on the carrier substrate 12 around each structure 11 instead of being deposited on the covers 7 around each hood cavity 8.

In addition, in the description of the figures, the hooking layer 6 is common to all the covers 7; alternatively, the mold 1 may comprise separate hooked layers deposited at each mold cavity 3.

Similarly, instead of using caps 7 separated from one another, the covers can be connected directly to each other and thus be grouped on the same plate forming several hood cavities 8.

In addition, the mold 1 can carry only one cover 7 and only one mold cavity 8, so as to encapsulate only one structure both individually and localized.

In addition, in the first embodiment instead of using the motors 14 and 16, the step of tearing the covers can be implemented for example using a system of claw, lever arm , or pneumatic cylinder, or can be implemented manually by an operator using an equivalent instrument. It is further noted that, in a variant of the manufacturing process of the mold 1, the deposition of the hook layer 6 is carried out by spin coating ("spin coating") or by spray coating. a liquid phase of PTFE.

In addition, each cover 7 may comprise a polymer such as benzo-cyclo-butene (BCB) or an epoxy resin, in particular an SU8-type resin rather than a metal. Each cover 7 may also include glass or silicon.

Finally, instead of a eutectic or polymer joint weld, the covers 7 can be fixed on the carrier substrate 12 by means of: a direct silicon weld comprising, for example, a heat emission by the source 18; this type of weld is applicable if for example each cover 7 and the carrier substrate 12 are made of silicon, or an anode solder comprising for example a heat emission by the source 18 and an application of an electrical voltage between each cover 7 and the carrier substrate 12; this type of weld is applicable if, for example, each cover 7 is made of glass and if the carrier substrate 12 is made of silicon, or of a heat-compression weld comprising, for example, a heat emission by the source 18 and the application of each cover 7 on the carrier substrate with high pressure; this type of weld is applicable if for example each cover 7 and the carrier substrate 12 both comprise copper metal joints arranged to be superposed during the application of each cover 7 on the carrier substrate.

Claims

A method of encapsulating at least one structure (11) carried by a carrier substrate (12), comprising:

- an application on the carrier substrate (12) of at least one cover (7) carried by a mold (1, 2, 6), the mold comprising a hook layer (6), each cover (7) being in contact with the hooked layer (6), then

- Fixing the at least one cover (7) on the carrier substrate (12), then

- A separation of the mold (1, 2, 6) and the at least one cover (7), characterized in that the hook layer (6) is made from a fluoropolymer.

2. Method according to claim 1, characterized in that the fluoropolymer comprises a fluorocarbon polymer, and preferably comprises polytetrafluoroethylene.

3. Method according to claim 1 or 2, characterized in that the mold (1, 2, 6) and the at least one cover (7) are separated mechanically by tearing off the at least one cover ( 7) the mold (1, 2, 6).

4. Method according to claim 3, characterized in that the mold (1, 2, 6) comprises a mold substrate (2) in contact with the hook layer (6), and in that the necessary breaking force to separate the mold substrate (2) and the hook layer (6) is greater than the breaking force necessary to separate the hook layer (6) and the at least one cover (7).

5. Method according to claim 1 or 2, characterized in that separates the mold (1, 2, 6) of the at least one cover (7) chemically, by dissolving the layer of hanging (6) .

6. Method according to claim 5, characterized in that dissolves the layer of hanging (6) in an acid bath or in a bath of solvent (19).

7. Method according to any one of the preceding claims, characterized in that the at least one cap (7) is fixed on the carrier substrate (12) by means of a polymer seal (9) or a eutectic seal (9) or a thermo-compression weld.

8. Method according to claim 7, characterized in that during the application, the seal is structured at at least one connection passage connected to the at least one structure.

9. Method according to any one of the preceding claims, characterized in that the at least one cover is perforated.

10. Method according to any one of the preceding claims, characterized in that the mold (1, 2, 6) comprises silicon atoms.

11. Method according to any one of the preceding claims, characterized in that each cover (7) comprises a metal layer in contact with the fluoropolymer (6).

12. Device for encapsulation (10) of at least one structure (11) carried by a carrier substrate (12), comprising:

- a mold (1, 2, 6) comprising a hook layer (6) and carrying at least one cover (7) so that each cover (7) is in contact with the hook layer (6),

means (13, 14, 15, 16) for applying to the carrier substrate (12) the at least one cover (7) carried by the mold (1, 2, 6),

means (9, 18) for fixing on the carrier substrate (12) the at least one cover (7) applied on the carrier substrate (12), - means (13, 14, 15, 16, 19) for separating the mold (1, 2, 6) and the at least one cover (7) fixed on the carrier substrate (12), characterized in that the layer hook (6) comprises a fluoropolymer.

13. Device according to claim 12, characterized in that the fluoropolymer comprises a fluorocarbon polymer, and preferably comprises polytetrafluoroethylene.

Device according to claim 12 or 13, characterized in that the separating means comprise means (13, 14, 15, 16) for mechanically separating the mold (1, 2, 6) and the at least one cover ( 7), arranged to pull the mold from at least one cover.

15. Device according to claim 14, characterized in that the mold (1, 2, 6) comprises a mold substrate (2) in contact with the hook layer (6), and in that the necessary breaking force to separate the mold substrate (2) and the hook layer (6) is greater than the breaking force necessary to separate the hook layer (6) and the at least one cover (7).

16. Device according to claim 12 or 13, characterized in that the separating means comprise means (19) for chemically separating the mold and the at least one cover, arranged to dissolve the hook layer.

17. Device according to claim 16, characterized in that the chemical separation means comprise an acid bath or a solvent bath.

18. Device according to any one of claims 12 to 17, characterized in that the fixing means comprise means (18) for welding a polymer gasket (9) or a eutectic seal (9) or welding means by thermo compression.

19. Device according to claim 18, characterized in that the seal comprises at least one structured part for at least one passage of a connection connected to the at least one structure.

20. Device according to any one of claims 12 to 19, characterized in that the at least one cover is perforated.

21. Device according to any one of claims 12 to 20, characterized in that the mold (1, 2, 6) comprises silicon atoms.

22. Device according to any one of claims 12 to 21, characterized in that each cover (7) comprises a metal layer in contact with the fluoropolymer.

An encapsulation mold (1, 2, 6) for an encapsulation device according to any one of claims 12 to 22, comprising: a mold substrate (2) comprising at least one mold cavity

(3), - a hook layer (6) deposited on one face (5) of the mold substrate (2) carrying the at least one mold cavity (3), the hook layer (6) comprising a fluoropolymer, characterized in that the mold carries, at each mold cavity (3), a cap (7) on the hook layer (6).

24. Mold according to claim 23, characterized in that the fluoropolymer comprises a fluorocarbon polymer, and preferably comprises polytetrafluoroethylene.

25. Mold according to claim 23 or 24, characterized in that the mold substrate (2) comprises silicon atoms.

26. Mold according to any one of claims 23 to 25, characterized in that each cover (7) comprises a metal layer in contact with the fluoropolymer.

Mold according to one of claims 23 to 26, characterized in that the breaking force required to separate the mold substrate (2) and the hook layer (6) is greater than the required breaking force. to separate the hook layer (6) and the at least one cover (7).

28. Mold according to any one of claims 23 to 27, characterized in that at least one of the covers is perforated.

The method of manufacturing a mold according to any one of claims 23 to 28, comprising:

an etching in a mold substrate (2), to form at least one mold cavity (3),

a deposition of a hook layer (6) on a face (5) of the mold substrate (2) carrying the at least one mold cavity (3), the hook layer comprising a fluoropolymer, characterized in that it further comprises a deposit, on the hooked layer, of a cover (7) at each mold cavity (3).

30. The method of claim 29, characterized in that the fluoropolymer comprises a fluorocarbon polymer, and preferably comprises polytetrafluoroethylene.

31. The method of claim 29 or 30, characterized in that after the deposition of the hook layer (6), the mold substrate (2) comprises silicon atoms.

32. A method according to any one of claims 29 to 31, characterized in that each cover (7) comprises a metal layer in contact with the fluoropolymer.

Method according to one of claims 29 to 32, characterized in that the breaking force required to separate the mold substrate (2) and the hook layer (6) is greater than the required breaking force. to separate the hook layer (6) and the at least one cover (7).

34. Process according to any one of claims 29 to 33, characterized in that at least one of the covers is perforated.

35. Process according to any one of claims 29 to 34, characterized in that the deposition of the hook layer (6) comprises an exposure of the mold substrate to a C ₄ F ₈ plasma.

36. Encapsulated structure obtained by the encapsulation process according to any one of claims 1 to 11.