MEMS device with particle filter and method of manufacturing

Abstract

MEMS device with particle filter and method of manufacturing. A MEMS sensor (1) with a medium inlet (MO) in its carrier board (CB) is disclosed, which has an integral filter mesh (MSH) closing the medium inlet. The mesh can be applied in unstructured form over the entire surface of the carrier board. Then, structuring is performed to preferably simultaneously produce perforations forming the filter mesh.

Description

Background Art

[0001] Various types of MEMS components require package openings for use as environmental access ports such as pressure sensors, gas sensors, and sensors for ultrasound or audible sound (ie, microphones), and actors such as ultrasound transmitters.

[0002] Depending on the construction and requirements of such components, they are susceptible to functional degradation or complete failure caused by particles entering the port and disturbing sensitive internal structures.

[0003] In particular, capacitive MEMS microphones are affected by this problem. In principle, the acoustic-electric transducer consists of two or more parallel plates, at least one of which (the "membrane") is impermeable and movable, and at least one other (the "backplate") is perforated and rigid. For optimized performance, the distance between these plates is very small (typically 1 ... 5 μm) to achieve good signal sensitivity, while the individual perforated openings are relatively wide (typically 5 ... 10 μm) to minimize airflow resistance and noise. Obviously, particles small enough to pass through the openings are large enough to block the gap and interfere with the free movement of the membrane caused by the sound pressure.

[0004] It is common practice to apply a protective member (net, fabric) between the component port and the housing port to keep off dust and moisture during the assembly of, for example, mobile phones. However, the components are not protected before and especially during the assembly process, which is usually not performed under strict clean room conditions. This causes yield losses and reliability issues. Summary of the invention

[0005] It is therefore an object of the present invention to provide a MEMS device and preferably a MEMS microphone with an improved particle filter that does not deteriorate the mechanical and electrical device performance too much. A further object is to provide a particle filter for the media access opening of a MEMS sensor that is easy to manufacture and retains smaller particles better than known dust grids.

[0006] The MEMS sensor according to the invention meets at least one of these objects.Preferred embodiments and variants as well as methods for manufacturing can be obtained from further aspects of the invention.

[0007] The MEMS sensor comprises in particular a MEMS chip mounted on a carrier board. The media inlet in the carrier board allows the following interaction of the environment with the MEMS sensor, which can sense at least one current environmental parameter, such as pressure, temperature or humidity. In order to prevent particles from reaching the MEMS chip and its sensitive or movable structures, a filter screen is provided between the media inlet and the MEMS chip. The filter screen is formed from a foil bonded to the top surface of the carrier board by means of an adhesive. After being applied in an unstructured form, the foil is structured by forming perforations in the perforated area above the media inlet before the MEMS chip is mounted.

[0008] Such perforations can be formed with a diameter substantially smaller than the diameter of known particle filters used in current MEMS sensors. The foil is applied without perforations, and the foil is therefore in an unstructured form, which provides better handling capabilities and higher stability than such a filter mesh. In addition, the foil can be selected from any suitable material that can be perforated. The filter mesh does not need to be an integral component of the carrier and therefore does not need to be suitable for the carrier in view of the choice of material. Therefore, in view of the grid formed integrally with the carrier and in view of the filter mesh attached to the surface in the form of a mesh, the thickness of the foil can be greatly reduced.

[0009] Structuring of the foil applied to a larger area than required can be done in the same step as forming the perforations.

[0010] When using a filter mesh for a MEMS sensor with a MEMS chip assembled in flip-chip technology, the low thickness allows the filter to be arranged below the chip, since the solder bump gap between the plate and the MEMS chip measures about 50 μm to 100 μm. The filter mesh according to the invention can be produced without problems with a thickness of 1 μm to 10 μm. Moreover, if, for example, the MEMS sensor is embodied as a capacitive sensor like a microphone, the filter mesh is not too close to the sensitive membrane of the MEMS chip, as is the case with a backplate. Thus, losses due to squeeze film damping are avoided. And finally, the filter mesh can be made thin enough and have a maximum perforation ratio, in the case of a microphone, achieving good acoustic performance while maintaining a sufficient level of robustness.

[0011] The foil may be selected, for example, from polyimide foils such as Furthermore, one can use, for example, or Like polyaramid (aromatic polyamide), for example. Furthermore, any polymer foil and metal foil may also be useful. In the area of ​​the medium inlet, the foil preferably has a thickness of about 1 μm to 10 μm to avoid the above-mentioned disadvantages. In the contact area where the foil is in direct contact with the carrier plate, and beyond the sensitive area of ​​the MEMS chip and beyond the medium inlet, the foil can have a greater thickness without interfering with the function of the MEMS sensor. The higher thickness at the outer margin of the foil can provide the filter mesh with a higher mechanical stability and robustness.

[0012] The perforations comprise a plurality of holes, each hole preferably having a diameter of 2 μm to 10 μm and arranged in a regular pattern. A maximum amount of perforations is sought. It is possible to provide an area ratio of perforations to perforated area of ​​30% or more, preferably 50% or more.

[0013] The MEMS chip has a sensing surface which generally comprises a movable microstructured part, such as a membrane. The MEMS chip is mounted to a carrier above the foil, maintaining a distance of at least 10 μm, preferably at least 50 μm, between the perforated area of ​​the foil and the sensing surface. A suitable compromise can then be made between bump height and foil thickness. However, it is preferred to minimize both of these geometric dimensions.

[0014] In an embodiment, the carrier has a multilayer structure with at least two dielectric layers sandwiching a wiring layer therebetween. Then, the medium inlet can be structured together with the structured corresponding dielectric layer at the same time. One of the dielectric layers can include a plurality of through-going holes in the region of the medium inlet to provide a filter grid across the medium inlet. Any other or all dielectric layers have only one hole / opening according to the diameter of the medium inlet. In the case of a grid formed in the dielectric layer in the region of the medium inlet, the diameter of the hole is greater than the diameter of the perforation in the foil. Then, using a coarse filter grid as the first stage and a finer filter mesh as the second stage, two-stage filtering is possible.

[0015] In an embodiment, the carrier consists of a multilayer laminate with internal electrical connections, through-holes and external solder contacts for surface mount components of the MEMS sensor. Typical materials are HTCC (High Temperature Co-fired Ceramic), LTCC (Low Temperature Co-fired Ceramic) or organic laminates (e.g. "FR4").

[0016] The MEMS chip is selected from any microstructured sensor chip. Preferably, the MEMS chip is a capacitive sensor or microphone for pressure, which comprises a membrane as a movable part and a rigid backplate forming a capacitor electrode. The sensor can also be an acceleration sensor, a gyroscope sensor or a humidity or chemical sensor.

[0017] The sensing area of ​​the MEMS chip usually coincides with the outer surface of the MEMS chip. In the MEMS sensor of the present invention, the sensing area can be arranged above the filter mesh and thus directly adjacent to the filter mesh. However, the opposite arrangement is also possible, so that the sensing area faces away from the carrier board.

[0018] The MEMS chip can be mounted by means of solder contacts, bumps or glue. In the latter case, a conductive adhesive can provide mechanical and electrical contact with the contact pads of the carrier. Alternatively, the electrical contact can be provided by wire bonding.

[0019] The carrier provides contact pads on the top surface and external contacts for the surface mount components of the MEMS sensor.

[0020] The foil can be applied and attached to the surface of the carrier in different ways. Since adhesive mounting is preferred, it is necessary to use and apply a separate adhesive or to use a self-adhesive foil.

[0021] The adhesive may be applied directly to the surface of the carrier according to the desired pattern, for example by dispensing, stamping or printing.The pattern comprises at least an edge region in the perimeter of the opening.

[0022] Alternatively, the adhesive can be applied as a viscous second foil or as a large-area layer of viscous adhesive, which is applied and attached to the carrier, covering the entire top surface of the board and, in the case of a viscous foil, also covering the media inlet. The second (viscous) foil has a preferred thickness in the range of 1 μm to 50 μm, more preferably about 10 μm. In a later step, the second foil is structured by removing the foil in the edge region of the perimeter of the opening required for the second foil to be bonded thereon. Therefore, no viscous foil remains over the media inlet.

[0023] A very suitable type of adhesive is a photoresist that allows for patterning by photolithography. In that case, the layer is exposed by a mask aligner. Alternatively, direct imaging by a scanning laser (LDI) is possible. In a development step, the unexposed foil areas are removed. When a positive resist is used, inversed patterning can be accomplished.

[0024] Other patterning methods (such as laser ablation) may also be employed.

[0025] The unstructured foil can be applied and attached to the pattern of adhesive by laminating the unstructured foil to the entire top surface of the carrier or to the pattern of adhesive. Heat and pressure can be applied for good adhesion. Polyimide (e.g. ) are very suitable as foils. Polyaramids, such as or The foil may be covered with a metal layer, which may be applied after lamination of the foil. In case existing features induce a topology of the carrier surface, the foil may have corresponding openings. A curing recipe depending on the requirements of the adhesive may be applied.

[0026] The foil then has to be cut to easily remove the overhanging area of ​​the foil so that the remaining foil that is covering the sound hole is held by the adhesive pattern or more generally by the bonding effect of the foil or the applied adhesive. This cutting can be done by a scanning laser, for example a UV laser with a spot size <100 μm, but also by an excimer laser can be used.

[0027] In an alternative variation, the steps of applying the adhesive and laminating the foil to the adhesive pattern can be replaced by using a self-adhesive foil. In a preferred embodiment, the foil comprises a polymer in the B stage and can be applied by lamination. After application, the foil is cured and hardened to provide the desired mechanical strength.

[0028] In a further alternative variant, the adhesive can be applied to the bottom side of the foil over its entire area or in a pattern before the foil is applied to a carrier, for example by lamination.

[0029] For the subsequent flip chip assembly of the silicon die, solder bumps can be applied to the contact pads on the substrate. This can also be done in an earlier step, but the flat surface of the substrate facilitates the lamination process of adhesive and foil. It is also possible to provide solder bumps at the silicon die.

[0030] Later in the process, the perforations are formed or preformed as a regular pattern of holes or blind holes in the perforated area of ​​the foil. The perforated area corresponds at least to the area of ​​the medium inlet. However, larger or smaller perforated areas are also possible.

[0031] A favorable hole pattern for perforation consists of holes with a diameter of 5 μm arranged at a pitch of 7 μm. Other patterns, pitches and non-circular holes can be used. The total opening ratio should be >30%, preferably about 50% or more relative to the self-supporting area of ​​the foil. Suitable tools for creating holes are excimer lasers or short pulse scanning lasers. As an alternative, photolithographical structuring and / or plasma etching can be applied.

[0032] In a next step, the MEMS chip can be mounted by means of the previously applied bumps such that the sensing area of ​​the MEMS chip and the medium inlet are arranged approximately coaxially.

[0033] Typically the MEMS chip needs to be sealed to the surface of the carrier. This can be done by applying a sealing mass along the bottom edge of the MEMS chip along the entire perimeter. Other sealing methods include applying a sealing foil from the top to the MEMS chip and carrier, thereby sealing the MEMS chip to the surface of the carrier. In the case of a capacitive sensor, parts of the sealing foil can be removed in the area of ​​the recess in the chip above the membrane electrode.

[0034] Further components of the MEMS sensor may be mounted adjacent to the MEMS chip such as an ASIC providing signal amplification and further signal processing and control of the sensor functions. This and any additional chips may also be sealed by the sealing foil.

[0035] In a final step, a cover may be mounted to the carrier to surround at least the MEMS chip below its concave portion. The cover may be mounted by using glue. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In the following, the present invention will be explained in more detail with reference to preferred embodiments and related drawings. For a better understanding, the drawings are only schematic and not drawn to scale. Identical or comparable parts are represented by the same reference numerals. Although the examples refer to a MEMS sensor embodied as a MEMS microphone, a large number of other MEMS sensors may also be similarly embodied.

[0037] Figure 1 A bottom port MEMS microphone according to the invention with a mesh comprising a foil with perforations is shown in cross section.

[0038] Figure 2 A bottom port MEMS microphone according to the invention having a mesh comprising a foil with perforations mounted on a pattern of adhesive is shown in cross section.

[0039] Figure 3 The cross-sectional view shows Figure 2 An arrangement of the opposite MEME chip, with a MEMS microphone comprising a mesh with a perforated foil mounted on a pattern of adhesive.

[0040] Figure 4 A MEMS microphone having a mesh comprising a foil with perforations having a reduced thickness in its central region is shown in cross section.

[0041] Figures 5 to 7 Different shapes of foils as may be used in a MEMS microphone according to the invention are shown.

[0042] Figure 8 8a to 8h show the MEMS microphone in cross-section after different production steps.

[0043] Fig. 9 d to 9i show in cross-sectional views different process stages of an alternative process for manufacturing a MEMS microphone. DETAILED DESCRIPTION

[0044] Figure 1 A first embodiment of a MEMS microphone 1 according to the invention is shown in a cross-sectional view. The microphone comprises a MEMS chip MC mounted on a carrier board CB such that a membrane and a back plate BP of the MEMS chip MC face a medium inlet MO in the carrier board CB. Furthermore, the MEMS microphone 1 comprises an ASIC SC, which is a small semiconductor chip that supports and controls the functions of the MEMS microphone 1.

[0045] The mesh MSH which has been formed by perforating a foil applied directly to the top surface of the carrier board CB spans the media inlet MO and provides a particle filter which retains particles having a diameter larger than the diameter of the holes forming the perforations. The cover CP is bonded or welded to the carrier board and surrounds the MEMS chip MC and the ASIC SC in its cavity. The acoustic seal seals the MEMS chip MC and the ASIC SC to the carrier board to provide a front volume for the microphone. Here, the acoustic seal comprises a foil laminated over the chip and structured to expose the back plate BP.

[0046] Figure 2 A similar MEMS microphone 1 is shown with the following difference: the foil is attached to the carrier by a pattern AP of adhesive. Furthermore, an acoustic seal AS is applied only to the bottom edge of the MEMS chip MC along its perimeter to seal the MEMS chip to the surface of the carrier CB only.

[0047] Figure 3A similar MEMS microphone is shown with the following differences: The MEMS chip MC and the ASIC SC are attached using adhesive GL. The back plate is oriented opposite to the carrier plate. The MEMS chip can be located on the edge of a foil F, which has perforations forming a net MSH. The foil is attached by a pattern AP of adhesive. The electrical contact of the MEMS chip and the ASIC SC is done via bonding wires.

[0048] Figure 4 The following differences are shown. Figure 2 The MEMS microphone shown in FIG. 4 is similar to the MEMS microphone shown in FIG. 4 : the foil is thinned in the central part from the top. Therefore, the edge of the foil F which exceeds the perforated area and is in contact with the carrier plate has a greater thickness. The mesh MSH including the perforations covers the medium inlet MO.

[0049] Figure 5 A top view of a foil F with perforations forming a web MSH is shown. The foil is structured into a rectangle to be placed between the bumps.

[0050] Figure 6 In the top view a foil F shape with concave rounded corners is shown. In the concave recesses bumps for mounting the MEMS chip MC can be placed.

[0051] Figure 7 In the top view the foil F is shown to be circular in shape. However, the foil F may have any other shape without departing from the invention.

[0052] Figure 8 8a to 8h show the MEMS microphone in cross-section after different production steps.

[0053] Figure 8 a shows a carrier board CB in cross section. It consists of a multilayer laminate with internal electrical connections, through holes and external solder contacts (not shown) for surface mounted components. Typical materials are HTCC (high temperature co-fired ceramic), LTCC (low temperature co-fired ceramic) or organic laminates (e.g. "FR4"). The dielectric inlet is located in the board CB, providing an inlet for external sound pressure to enter the package. As shown, the hole can have different sizes in various layers. It is also possible to have one hole in one layer and multiple smaller holes in another layer. The shape of the hole can be circular or other shapes. Only one unit site is shown. In a preferred embodiment of the present invention, the arrangement of multiple such units formed on the same carrier board ("panel") is processed in parallel. Singularization (i.e. cutting into separate parts) is completed after performing some or all steps of the method.

[0054] Figure 8b shows the carrier after being coated with a thin layer of adhesive AL, typically with a thickness between 1 μm and 50 μm, preferably about 10 μm.

[0055] Figure 8 c: The adhesive layer AL has been patterned. Very suitable types of adhesives can allow for patterning by photolithography. In this case, the layer is exposed by a mask aligner or scanning laser direct imaging (LDI) and then developed. Other patterning methods (such as laser ablation) can be used. As an alternative, Figure 8 The step in b can be omitted and the adhesive can be directly applied according to the desired pattern, for example by dispensing, embossing or printing. Regardless of the method, a high viscosity (>10 Pas) of the adhesive is advantageous. Preferably, the adhesive may have a thixotropic property, and further preferred are solid polymers in the "B stage" that melt under heat and pressure before starting to solidify. The adhesive chemistry can be based on epoxy, imide, acrylate or a mixture. The most appropriate pattern is a closed ring around the medium inlet MO. However, additional areas may also be present at other locations.

[0056] Figure 8 d: A thin foil (typical thickness 1 μm to 10 μm) is laminated onto the adhesive pattern AP across the entire carrier. Heat and pressure may be applied for good adhesion. Polyimide (e.g. ) are very suitable. Other polymer or metal films can also be used. In case existing features induce a topology of the carrier surface, the foil F can have corresponding openings. A curing recipe depending on the requirements of the adhesive can be applied.

[0057] Figure 8 e: The foil F has been cut so that the remaining foil covering the media inlet MO is held by the adhesive pattern AP, while the surrounding foil is easily removed. This cutting can be achieved by a scanning laser, such as a UV laser with a spot size <100 μm or by an excimer laser.

[0058] Figure 8 f: For the subsequent flip-chip assembly of the MEMS chip MC, solder bumps B are applied to the contact pads on the carrier board CB. This could also be done in an earlier step, but the flat surface facilitates the lamination process. It is also possible to provide solder bumps on the MEMS chip MC.

[0059] Figure 8g: Now apply the perforations. An advantageous pattern consists of holes with a diameter of 5 μm arranged at 7 μm spacing to achieve high acoustic transparency. Typically, hole sizes from 1 μm to 10 μm may be useful. The minimum distance between the holes is 1 μm when measured from edge to edge. Other patterns, spacings and non-circular holes can be used. Relative to the self-supporting area of ​​the foil (perforated area above the medium inlet), the total opening ratio should be >30%, preferably about 50% or more. Suitable tools for creating the holes are excimer lasers or short pulse scanning lasers. As an alternative, photolithographic structuring can be applied.

[0060] Figure 8 h: Solder the MEMS chip onto solder bump B.

[0061] Fig. 9 d to 9i show in cross-sectional views different process stages of an alternative process for manufacturing a MEMS microphone.

[0062] In this alternative process flow, the laser used to drill the holes does not have to drill through the entire polymer foil, but only through a very thin (0.1 μm-1.0 μm) etching mask layer, preferably a metal layer ML like Ti, Al or Cr sputtered onto the polymer foil F. By this, blind holes BH are created.

[0063] In the next step, the etching is carried out by means of a plasma etching process (e.g. RIE, reactive ion etching, using a plasma etching process such as O 2 CF 4 , SF 6 or the like, or a gas or mixture thereof) a hole pattern is etched through the polymer foil. Anisotropic etching properties are preferred.

[0064] This method makes it easier to achieve appropriate hole geometries with well-defined shapes and cross-sections and narrow spacings on the one hand, and on the other hand requires only very short laser processing times with low thermal impact.

[0065] It is not necessary to subsequently remove the etching mask, i.e. the perforated metal layer ML, since this layer does not contribute significantly to the thickness of the filter mesh MSH. Therefore, there is practically no degradation of the acoustic performance of the microphone. On the contrary, this metal layer ML adds a very advantageous feature to the assembly, since it

[0066] -- Helps shield light and infrared radiation from entering the microphone's sound port, which could otherwise affect the semiconductor chip contained in the microphone package as well as the MEMS chip by generating leakage current. This will cause noise

[0067] -- Improved protection of the component against electromagnetic interference and electrostatic discharge, especially when the metal layer ML is connected to ground by any suitable means.

[0068] This alternative process starts from Fig. 9 d starts, Fig. 9 d shows the first alternative explained above. Figure 8 d Same stage. A foil F of, for example, 5 μm polyimide has been laminated on an adhesive pattern AP applied on the surface of a circuit board CB.

[0069] A thin metal layer ML, for example 200 nm of Ti, is deposited on the foil F, for example by sputtering. Fig. 9 e shows the arrangement at this stage. Further shown are arrows pointing to the cutting lines for the structured foil F and the metal layer ML thereon. Fig. 9 f shows a structure with, for example, a circular CO 2 The laser cut structured metal layer foil F. The area is now limited to covering the medium inlet MO plus the edges at ther perimeter of the opening.

[0070] according to Fig. 9 g, applying bumps B to the circuit board for subsequent mounting of the MEMS chip thereon.

[0071] Fig. 9 h shows a stage at which a pattern of blind holes BH has been drilled by laser. The blind holes do not go through the entire polymer foil but only through a very thin structured metal layer ML.

[0072] In accordance with Fig. 9 In the next step of i, by means of a plasma etching process (e.g. RIE, reactive ion etching, using a method such as O 2 CF 4 , SF 6 or the like, or a mixture thereof) by etching through the metal layer ML has completed the perforation PF. Preferably, anisotropic etching characteristics are set.

[0073] Thereafter, the fabrication of the MEMS sensor is completed as described above.

[0074] In a further alternative embodiment, a thicker foil F (about 10 μm to 50 μm) is used, in particular a foil having an adhesive layer on its lower surface or having inherent adhesiveness. In this case, no Figure 8 b and 8c. For acoustic reasons, it may be necessary to locally reduce the thickness in the central area to 1 μm to 10 μm. This is possible with the same excimer laser. Figure 4 The MEMS sensor thus produced is depicted in In a similar method, a local thinning of the foil in a central region is performed from the opposite side of the foil F.

[0075] Although there are a number of exemplary embodiments, the present invention is not limited to the embodiments shown. The MEMS chip can be any kind of sensing chip that requires a medium to enter.

[0076] The scope of the present invention should be limited only by the terms of the claims.

[0077] List of reference symbols used

[0078] 1MEMS Sensor

[0079] AL adhesive layer

[0080] AP Adhesive Pattern

[0081] AS Acoustic Seal

[0082] B Bump

[0083] BH blind hole

[0084] BP Backplane

[0085] CB carrier board

[0086] CP cover

[0087] The DL dielectric layer has

[0088] F Foil

[0089] GL Adhesive

[0090] GRD Filter Grid

[0091] MC MEMS Chip

[0092] ML Metal Layer

[0093] MO medium inlet

[0094] MSH filter screen

[0095] PA perforation area

[0096] PF perforation

[0097] SCASIC.

Claims

1. A method for manufacturing a MEMS sensor, comprising the steps of - providing a carrier board (CB) with a medium inlet (MO), - Apply a foil (F) onto the top surface of the carrier plate, completely covering the media inlet, - providing perforations (PF) in a perforated area (PA) of the foil (F), the perforated area (PA) extending at least partially over the area of ​​the media inlet (MO), wherein the perforations form a filter mesh and the foil (F) has a thickness of 1 μm to 10 μm in the area of ​​the media inlet (MO), - mounting a MEMS chip (MC) having a surface with a sensing area on the top surface of a carrier board (CB) such that a medium to be sensed can reach the sensing area through a medium inlet (MO); wherein the foil (F) is bonded to the top surface by means of an adhesive; Wherein the foil (F) comprises a polymer in the B-stage, which acts as foil and adhesive, the foil (F) is applied by lamination and the foil is cured after application.

2. The method according to claim 1, in, The material of the foil is selected from the group of polymer, polyimide foil, aramid polymer foil and metal foil.

3. The method according to any one of the preceding claims 1 and 2, in, The perforations include a plurality of holes having a diameter of 2 μm to 10 μm and arranged in a regular pattern to provide an area ratio of the perforations to the perforated area (PA) of 30% or more.

4. The method according to any one of the preceding claims 1 and 2, in, The perforations include a plurality of holes having a diameter of 2 μm to 10 μm and arranged in a regular pattern to provide an area ratio of the perforations to the perforated area (PA) of 50% or more.

5. The method according to any one of the preceding claims 1 and 2, - in, MEMS chip has a sensing surface - wherein the MEMS chip is mounted to a carrier above the foil such that a distance of at least 10 μm is maintained between the perforated area of ​​the foil and the sensing surface.

6. The method according to any one of the preceding claims 1 and 2, - in, MEMS chip has a sensing surface - wherein the MEMS chip is mounted to a carrier above the foil such that a distance of at least 50 μm is maintained between the perforated area of ​​the foil and the sensing surface.

7. The method according to any one of the preceding claims 1 and 2, - in, The MEMS chip (MC) is mounted on a carrier board (CB) in a flip chip assembly.

8. The method according to any one of the preceding claims 1 and 2, - in, The carrier board (CB) has a multilayer structure with at least two dielectric layers and a wiring layer sandwiched between them. - Wherein the medium inlets (MO) are structured individually in the layer - wherein all dielectric layers comprise one or more through holes in the region of the media inlet, wherein one of the dielectric layers comprises one or more through holes in the region of the media inlet to provide a filter grid (GRD) across the media inlet (MO) - wherein the diameter of the holes of the filter mesh (GRD) is at least 10 times larger than the diameter of the perforations.

9. The method according to any one of the preceding claims 1 and 2, in, The foil (F) consists of an organic material and is mounted on a carrier board (CB) by gluing.

10. The method according to any one of the preceding claims 1 and 2, - in, The foil (F) is applied to the entire area of ​​the carrier board (CB) - wherein, after application, the structured foil is limited in area to the area of ​​the medium inlet (MO) of the top surface plus an edge area in the perimeter of the medium inlet (MO), - wherein the foil is bonded to the surface of the carrier board in the edge region - wherein forming the perforations (PF) and structuring the foil are performed in the same way and in the same step.

11. The method according to any one of the preceding claims 1 and 2, - in, The foil (F) is applied to the entire area of ​​the carrier board (CB) wherein, after application, the structured foil is limited in area to the area of ​​the medium inlet (MO) on the top surface plus an edge area in the perimeter of the medium inlet, - wherein the foil is bonded to the surface of the carrier board in the edge region - wherein the perforations (PF) are first preformed as blind holes (BH) - wherein a plasma etching step is then performed to etch blind vias until a through-hole (PF) penetrates through the foil (F).

12. The method according to any one of the preceding claims 1 and 2, in, Lasers are used for structuring the foil (F) and for forming perforations (PF) or blind holes (BH).

13. The method according to any one of the preceding claims 1 and 2, comprising - applying a metal layer (ML) to the entire surface of the foil (F), - Forming a blind hole (BH) at least through the metal layer to form an etching mask for subsequent formation of a through hole (PF) by etching.

14. The method according to any one of the preceding claims 1 and 2, in, Photolithographic structuring is used to form the perforations (PF) and / or the structured foil (F).

15. The method according to any one of the preceding claims 1 and 2, in, Mounting the MEMS chip (MC) to the carrier board (CB) includes soldering or gluing wherein, after its mounting, the MEMS chip is sealed to the top surface of the carrier by a seal to surround the volume between the MEMS chip, the seal and the carrier, Therein, the perforated area (PA) is arranged completely within the volume.

16. A method according to any one of the preceding claims 1 and 2, wherein a package is formed between the cover and the carrier around the MEMS chip (MC) and at least another chip required for the operation of the MEMS chip by applying a cover (CP) over the MEMS chip (MC) and sealing it to the top surface of a carrier (CB).

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