EP2438767B1 - Component with a micromechanical microphone structure and method for production such a component - Google Patents

Description

State of the art

The invention relates to a component with a micromechanical microphone structure. The microphone structure includes an acoustically active diaphragm that acts as a deflectable electrode of a microphone capacitor, a fixed acoustically transmissive mating element that acts as a counter electrode of the microphone capacitor, and means for detecting and evaluating the capacitance changes of the microphone capacitor. The membrane is realized in a membrane layer over the semiconductor substrate of the device and spans a sound opening in the back of the substrate. The counter element is formed in a further layer over the membrane.

Furthermore, the invention relates to a method for producing such components in the wafer composite and subsequent separation.

• eine akustisch aktive Membran, die als auslenkbare Elektrode eines Mikrofonkondensators fungiert,
• ein feststehendes akustisch durchlässiges Gegenelement, das als Gegenelektrode des Mikrofonkondensators fungiert, und
• Mittel zum Erfassen und Auswerten der Kapazitätsänderungen des Mikrofonkondensators, wobei die Membran in einer Membranschicht über dem Halbleitersubstrat des Bauelements realisiert ist und eine Schallöffnung in der Substratrückseite überspannt, und wobei das Gegenelement in einer weiteren Schicht über der Membran ausgebildet ist; wobei sich diese weitere Schicht im wesentlichen über die gesamte Bauelementfläche erstreckt.

The document DE 10 2004 011145 shows a component including method for its production with a micromechanical microphone structure, at least comprising

• an acoustically active membrane, which acts as a deflectable electrode of a microphone capacitor,
• a fixed acoustically permeable counter element, which acts as a counter electrode of the microphone capacitor, and
• Means for detecting and evaluating the capacitance changes of the microphone capacitor, wherein the membrane is realized in a membrane layer over the semiconductor substrate of the device and spans a sound opening in the substrate back, and wherein the counter-element is formed in a further layer over the membrane; wherein this further layer extends substantially over the entire component surface.

In the US 2002/0067663 A1 a microphone component of the type mentioned is described, the micromechanical microphone structure is realized in a layer structure over a semiconductor substrate. The perforated counter element here forms a base-like elevation in the device surface and is adapted to the size of the underlying membrane. This spans a sound opening in the back of the substrate. Between the counter element and the membrane there is an air gap, which was produced by sacrificial layer etching. In the known microphone component, the rigidity of the counter element depends substantially on its peripheral shape, ie on the shape of the base edge region, by which the counter element is kept at a distance from the diaphragm.

For cost reasons, the production of such microphone components takes place as far as possible in the wafer composite. Usually, a multiplicity of microphone structures arranged in a grid are produced on a semiconductor wafer for this purpose. Only then are the components separated. In this case, the very fragile and sensitive to water structure of the known microphone component proves problematic.

The cost-effective sawing with water-cooled circular saw, which is widespread in microtechnology, can not be considered without additional protective measures for these components. So it can be assumed that the sensitive microphone structures can not withstand the impinging jet of water. In addition, water that gets between the two electrodes of the microphone capacitor leads to irreversible adhesion of the membrane to the counter element, whereby the microphone function is also disabled.

Therefore, the separation of micromechanical microphone components of the type mentioned above is done so far with the help of special processes. Particularly often the so-called stealth dicing is used, are generated in the predetermined breaking points in the wafer material. Subsequently, the wafer is broken into individual chips along these predetermined breaking points, partly with the aid of a doctor blade. For this special machines and thus additional investment costs are required. In addition, the process times of the typically used 400 .mu.m to 800 .mu.m thick wafers are relatively long, not least because of the high number of required "laser cuts".

Disclosure of the invention

With the present invention, a device with a stable but acoustically sensitive microphone structure is proposed as well as a simple and inexpensive method for its production.

This is inventively achieved in that - in contrast to that from the US 2002/0067663 A1 known microphone component - the further layer in which the counter-element is formed extends substantially over the entire component surface and compensates for differences in level, so that the entire device surface is largely flat according to this further layer.

According to the invention, it has been recognized that it has an advantageous effect on the rigidity of the mating element of the microphone structure when the mating element is formed in a relatively thick layer which extends over the entire component surface and compensates for differences in level. In this case, the counter element is integrated with equal rigidity on all sides, the strength essentially depending only on the layer thickness. The thicker the layer, the stiffer the counter element, the stronger the counter element is integrated in the layer structure of the component and the better the leveling effect, especially in the edge region of the counter element.

According to the invention, it has also been recognized that the thus modified microphone structure of the known component can be easily produced in a sequence of processes of bulk and surface micromechanics, as already used in the production of inertial sensors. The largely flat component surface simplifies in particular the separation of the microphone components according to the invention, which will be explained in more detail in connection with the production method according to the invention.

In principle, there are various possibilities for the realization of the microphone structure according to the invention.

From the viewpoint of mass production of microphone components with identical acoustic properties as possible, it proves to be advantageous if the membrane layer of the microphone device according to the invention is realized in the form of a thin polysilicon layer which is electrically insulated from the semiconductor substrate by a first insulating layer, and if the counter element in a thick epi-polysilicon layer is formed, which is electrically insulated from the membrane layer by a second insulating layer. The layer thickness of this second insulation layer determines the distance between the membrane and the counter element. Well-controlled standard methods of bulk and surface micromechanics are available for the production of such a layer structure with predetermined defined layer thicknesses.

However, the acoustic properties of the microphone component in question here are determined not only by the distance between the membrane and the counter element, but also by the intrinsic stresses in the layer structure and in particular in the membrane. Uncontrolled voltages within the membrane can lead to undesired deflection of the membrane and thus alter the sensitivity-determining properties of the microphone capacitor. Therefore, a stress-relaxing spring suspension for the membrane is formed in the membrane layer of an advantageous development of the microphone component according to the invention. The spring elements thus consist here of the same material as the membrane and are as far as possible designed to compensate for the layer stresses which occur during the production of the thin polysilicon layer and which are difficult to control. Due to this layer stress compensation, the sound pressure sensitivity of the membrane is essentially determined only by its bending stiffness. The spring suspension of the membrane also contributes to the maximization of the microphone use signal, since a sound pressure-induced deformation preferably occurs in the region of the spring elements, while the contributing to the measuring capacity membrane is deflected almost plane-parallel to the counter electrode. The influence of occurring in the connection region of the membrane parasitic capacitances is comparatively low due to the recesses between the spring elements. Therefore, the resonance frequency of the membrane and thus the acoustic working range of the microphone component according to the invention on the design of the spring suspension in conjunction with a defined predeterminable layer thickness of the membrane can be adjusted very easily controlled.

The spring suspension advantageously comprises at least three spring elements. The fixed points of these spring elements can be embedded between the first and the second insulating layer and thus connected to the semiconductor substrate and the counter element. Alternatively, however, the spring elements can also be connected via one of the two insulation layers either to the semiconductor substrate or to the counterelement.

As already mentioned, in addition to the microphone component described above, a particularly advantageous method for producing such components is also proposed. Accordingly, first a first electrically insulating Sacrificial layer applied to a semiconductor substrate. A membrane layer is then applied to this first sacrificial layer and patterned in order to produce for each component at least one membrane with a spring suspension. Thereafter, a second electrically insulating sacrificial layer is applied to the structured membrane layer, to which then at least one further layer is applied and patterned in order to produce an acoustically permeable counter element for each membrane. In addition, at least one sound opening is produced under each membrane in the rear side of the semiconductor substrate. The first sacrificial layer and the second sacrificial layer are now removed at least in the area below and above each membrane and its spring suspension. Only after the exposure of the microphone structures, the components are finally isolated.

As a membrane layer, a thin polysilicon layer is advantageously deposited on the first sacrificial layer. In addition, it proves to be advantageous to grow on the second sacrificial layer a thick epi-polysilicon layer as a further layer in which the counter-elements are formed.

The process sequence of this method variant for producing a microphone component is based on a proven and easily controllable method for the production of inertial sensors. Thus, the polysilicon layer used according to the invention as a membrane layer is used in the case of the production of inertial sensors for the realization of buried interconnects. And in the case of the inertial sensors, the thick epi-polysilicon layer in which the counterelements are realized according to the invention serves as a functional layer.

On the one hand, the first and the second electrically insulating sacrificial layer have the function of an electrical insulation between the two electrodes of the microphone capacitor and with respect to the semiconductor substrate. On the other hand, the membranes are exposed using the sacrificial layers. Within the scope of the method according to the invention, these sacrificial layers may additionally each have the function of an etch stop boundary. Thus, the second sacrificial layer advantageously acts as an etch stop in the structuring of the counterelements or the thick epi-polysilicon layer, if this takes place in an anisotropic etching process, in particular in a trench process or in a DRIE process. The first sacrificial layer advantageously acts as an etch stop in the generation of the Sound openings in an anisotropic etching process, especially in a DRIE process.

To release the membranes, the first sacrificial layer and the second sacrificial layer are advantageously removed in an isotropic etching process, wherein the etching attack takes place via the sound openings and through passage openings in the counterelements. SiO 2 or SiGe are particularly suitable as sacrificial layer materials.

The use of a sacrificial SiGe layer with ClF3 as etching gas is particularly advantageous because of the high selectivity of the etching process compared to numerous materials used in microsystems technology, and in particular to silicon. This etching process is characterized by its high etching speed and the large undercuts that can be achieved with it. In addition, SiGe sacrificial layers are particularly stress-free, so that relatively thick sacrificial layers and thus large electrode spacings can be realized with this material without additional voltages being introduced into the component structure. This increases the freedom of design in the design of the microphone component.

As already mentioned, the microphone structures according to the invention are exposed in the wafer composite and only then separated. A particularly advantageous variant of the method according to the invention makes use of the structure of the microphone component according to the invention, namely that the layer in which the counter-elements are realized, located at the top of the layer structure and that this layer is relatively thick and stable and according to the invention largely flat , These layer properties enable the application of a protective film, which reliably prevents the penetration of particles and liquid into the microphone structures. In this way, the microphone components can be singulated in a sawing process standardized in micromechanics, which has enormous cost advantages compared with the methods currently used for singulating microphone components. After separation, the protective film is removed as far as possible without residue.

In this connection, it proves to be advantageous to use a protective film which loses its adhesive power by UV irradiation or by a heat treatment or by UV irradiation in combination with a heat treatment. Such a protective film can easily under vacuum the largely flat surface of the layer structure are laminated and after the separation process by a UV irradiation in combination with a heat treatment without residue and without damaging the microphone structures are again detached from the component surfaces.

Brief description of the drawings

Fig. 1

zeigt eine schematische Schnittdarstellung durch die Mikrofonstruktur eines erfindungsgemäßen Bauelements 10,

Fig. 2a bis 2f

veranschaulichen anhand von schematischen Schnittdarstellungen des Schichtaufbaus das erfindungsgemäße Verfahren zur Herstellung der in Fig. 1 dargestellten Mikrofonstruktur,

Fig. 3

zeigt die Draufsicht auf eine kreisrunde Membran mit Federaufhängung eines erfindungsgemäßen Mikrofonbauelements, und

Fig. 4a bis 4f

veranschaulichen anhand von schematischen Schnittdarstellungen den erfindungsgemäßen Vereinzelungsprozess von im Waferverbund erzeugten Mikrofonstrukturen.

As already discussed above, there are various possibilities for embodying and developing the teaching of the present invention in an advantageous manner. For this purpose, reference is made on the one hand to the claims subordinate to the independent claims and on the other hand to the following description of several embodiments of the invention with reference to FIGS.

Fig. 1

shows a schematic sectional view through the microphone structure of a device 10 according to the invention,

Fig. 2a to 2f

illustrate on the basis of schematic sectional views of the layer structure, the inventive method for producing the in Fig. 1 represented microphone structure,

Fig. 3

shows the top view of a circular diaphragm with spring suspension of a microphone component according to the invention, and

Fig. 4a to 4f

illustrate on the basis of schematic sectional views of the singulation process according to the invention of microphone structures generated in the wafer composite.

Embodiments of the invention

This in Fig. 1 illustrated component 10 comprises a micromechanical microphone structure with a deflectable acoustically active membrane 11 and a fixed acoustically permeable counter-element 12, which is also referred to as backplate. The membrane 11 and the counter element 12 are realized here in a layer structure on a semiconductor substrate 1. In the back of the Semiconductor substrate 1, a sound opening 13 is formed, which extends over the entire thickness of the semiconductor substrate 1 and is spanned by the arranged on top of the semiconductor substrate 1 membrane 11. The membrane 11 is realized in a thin polysilicon layer 3 and electrically insulated by a first insulating layer 2 against the semiconductor substrate 1. The deflectability of the thin membrane 11 is favored by its formed in the polysilicon layer 3 spring suspension 14. In contrast, the counter element 12 is formed in a relatively thick epi-polysilicon layer 5 over the membrane 11 and fixedly connected to the layer structure. The counter-element 12 is electrically insulated via a second insulation layer 4 both against the membrane 11 and against the semiconductor substrate 1. The thickness of this second insulating layer 4 also determines the distance between the diaphragm 11 and counter element 12 in the idle state. In the middle region of the counter element 12, passage openings 15 are formed, so that the counter element 12 is acoustically permeable and does not impair the sound-induced deflections of the diaphragm 11.

The membrane 11 and the counter-element 12 form the electrodes of a microphone capacitor whose capacitance changes with the distance between the diaphragm 11 and the counter-element 12. For detecting the capacitance changes of the microphone capacitor, a charging voltage is applied between the diaphragm 11 and the counter electrode 12, which is also referred to as a bias voltage. The means for detecting and evaluating the capacitance changes of the microphone capacitor are not shown here in detail.

According to the invention, the epi-polysilicon layer 5, in which the counter-element 12 is formed, extends over the entire device surface and compensates for differences in level, so that the entire device surface corresponding to this epi-polysilicon layer 5 is substantially planar. This proves to be particularly advantageous in connection with the separation of these components, which will be described below in connection with FIGS FIGS. 4a to 4f will be explained in more detail.

A particularly advantageous variant of the method for producing the microphone structure of in Fig. 1 illustrated component 10 will be described below in connection with the FIGS. 2a to 2f described. The starting point of this procedure forms a semiconductor substrate 1, for example in the form of a silicon wafer, as in Fig. 2a is shown. In a first method step, a first electrically insulating sacrificial layer 2 was applied to the wafer front side. This may be an SiO 2 layer or even a SiGe layer. Over the first sacrificial layer 2, a membrane layer 3 was then deposited and patterned to produce at least one membrane with a spring suspension for each component. An example of such a membrane structure is in Fig. 3 and will be explained in more detail in connection with this figure. In the exemplary embodiment described here, the membrane layer 3 is a polysilicon layer whose layer thickness is between 0.1 μm and 3 μm, depending on the requirements of the microphone component.

Fig. 2b shows the layer structure after a second electrically insulating sacrificial layer 4 has been applied to the structured membrane layer 3 and patterned. With the structuring of the second sacrificial layer, the electrical contacting of the microphone structure was prepared here. Advantageously, the same material is selected for the two sacrificial layers 2 and 4, which can then be removed in a subsequent process stage in a common etching process from the front and from the back of the membranes.

On the second sacrificial layer 4, a thick epi-polysilicon layer 5 was then produced, which is shown in FIG Fig. 2c is shown. For this purpose, the layer material is advantageously grown epitaxially from the gas phase starting from a starting layer of thin LPCVD polysilicon. The thickness of an epi-polysilicon layer 5 thus produced may be of the order of magnitude of 3 μm to 20 μm, depending on the requirements of the microphone component. Fig. 2c illustrates that the layer structure was leveled by means of the epi-polysilicon layer 5, which is favored by the deposition process in conjunction with the relatively large layer thickness. The planar surface of the epi-polysilicon layer 5 has now been provided with a structured metallization 6, which likewise serves for contacting the individual components of the microphone structures. However, such a metallization can also be applied to the layer structure at a later time in the production process.

Fig. 2d shows the layer structure after the structuring of the epi-polysilicon layer 5 in an anisotropic trench process or in a DRIE process. there the second sacrificial layer 4 was used as the etch stop limit. In the context of this structuring, the counter-elements 12 of the microphone structures within the epi-polysilicon layer 5 were exposed and provided with passage openings 15. The trench trenches 7 serve not only to define but also to electrically decouple individual regions of the epi-polysilicon layer 5. Thus, in the structuring of the epi-polysilicon layer, the contact regions 16 and 17 for the substrate 1 and the membranes have also been defined.

Thereafter, in the exemplary embodiment illustrated here, the sound openings 13 were produced in an anisotropic DRIE process emanating from the substrate rear side, which is shown in FIG Fig. 2e is shown. The sacrificial layer 2 formed the etch stop boundary for this backside etching process, which can just as well be performed before the structuring of the epi-polysilicon layer 5.

Finally, the diaphragms 11 of the microphone structures and the associated spring suspensions 14 were exposed by means of isotropic sacrificial layer etching. The required etching attack took place simultaneously from both sides of the layer structure. In this case, the etching gas reached the sacrificial layer 4 from the front side via the trenches 7 and the through openings 15 and from the back via the sound openings 13 to the sacrificial layer 2. In the case of SiO 2 sacrificial layers, the sacrificial layer material is preferably dissolved out with HF vapor. For SiGe sacrificial layers, ClF3 is used as the etching gas. Fig. 2f shows the in Fig. 1 illustrated microphone structure as a result of this etching process and illustrates that the distance between the diaphragm 11 and counter element 12 by the layer thickness of the sacrificial layer 4 is determined.

According to the method described above, the membranes of the microphone components according to the invention are realized together with their spring suspensions in a thin polysilicon layer. The spring elements of the individual membranes are designed as much as possible so that the membranes are largely independent of the layer tension of the membrane material suspended. Fig. 3 shows an advantageous layout for the spring suspension of a circular membrane 30. The membrane 30 is suspended here on a total of six spring elements 31. The spring elements 31 are realized in the form of curved webs which are arranged along the circumference of the membrane and each extend over one sixth of the circumference of the membrane. An end to everyone Spring element 31 is connected to the membrane 30, while the other end is integrated into the surrounding edge region of the layer structure. For this purpose, these ends of the spring elements 31 may, for example, be embedded between the two sacrificial layers such that they are connected both to the counter element and to the substrate. Alternatively, however, these spring ends can also be connected on one side only to either the counter element or the substrate. The spring suspension shown here is designed so that it can compensate for the occurring during the production of the polysilicon membrane layer and difficult to control layer voltages, at least within certain limits, when the polysilicon was deposited Tensile, as well as when it was deposited compressively.

The membrane 30 shown here is stably suspended via the spring elements 31. The deformation during pressurization takes place mainly in the region of the spring elements 31. As a result, the membrane surface acting as the movable electrode, which is decisive for the microphone function, is deflected approximately plane-parallel to the counter element, which has a favorable effect on the microphone user signal.

In the embodiment described here, a simple electronic function is provided as overload protection for the microphone structure. The transmitter automatically detects a striking of the membrane on the counter element, which in case of overload, e.g. at very high sound pressure or shock. In order to solve the occurring electrostatic adhesive forces and to avoid a permanent electrostatically induced adhesion of the membrane to the counter element, the bias voltage is temporarily interrupted. In the tension-free state, the membrane can then automatically detach again from the counter element. This concept is particularly suitable for bias voltages of less than 5 V, since at these low bias voltages still no electrical welding can take place between membrane and counter element.

As in connection with the FIGS. 2a to 2f described, the production of the microphone structures according to the invention including the exposure of the membranes in the wafer composite takes place. The following is in conjunction with the FIGS. 4a to 4f a particularly advantageous method for separating these microphone structures described.

First, with the aid of a vacuum laminator, a protective film 41 with special adhesion properties is applied to the largely planar upper side of the layer structure 40 which is according to the invention Fig. 4a is shown. This protective film 41 loses its adhesive force when exposed to UV light in combination with heat, which allows a simple, residue-free detachment of the protective film 41 after the singulation process.

Fig. 4b shows the layer structure 40 with the protective film 41 after it has been glued onto a saw frame covered with a sawing foil 42. The sawing foil 42 must be heat-resistant at least to the extent that it is insensitive to temperatures at which the protective foil 41 loses its adhesive force. In addition, the adhesive force of the protective film 41 and the adhesive force of the sawing foil 42 must each be so large that chips with a chip size of, for example, 1x1 mm ² remain stuck during a sawing process.

Since the layer structure 40 and in particular the microphone structures exposed in the layer structure 40 are protected by the protective film 41, the layer structure 40 can now be sawn with the aid of a water-cooled circular saw. The protective film 41 effectively prevents the penetration of water or sawing particles into the microphone structures. In Fig. 4c the layer structure 40 with the protective film 41 is already sawn. However, the individual components 50 still adhere to the continuous sawing foil 42.

After the sawing process, the protective film 41 can be removed from the top of the individual components 50. For this, it is first exposed to UV radiation. This is followed by a temperature treatment, during which the laminated protective film 41 completely dissolves from the top of the component. Accordingly, after the temperature treatment on each component 50 pieces of film that can be sucked off or blown off. In the embodiment described here, the film pieces are recorded with a stamping process, which in the Fig. 4d and 4e is shown. For this purpose, a second wafer 43 is used, on the stamp surface of which a two-sided adhesive film 44, a soft polymer layer or a soft lacquer layer has been applied.

Thereafter, the sawing foil 42 can be expanded and the individual components 50 can be picked and packed with pick-and-place tools of the sawing foil 42, which by Fig. 4f is illustrated.

The microphone structure according to the invention with a largely planar component surface makes it possible to apply a protective film to the top side of the wafer layer structure. As a result, the microphone components according to the invention can be singulated in a standard sawing process, wherein the additional process complexity caused by the application and removal of a second film is negligible. Since the protective film 41 itself is also relatively inexpensive, its use within the scope of the singulation method contributes only insignificantly to the overall costs of a single component.

Claims (14)

1. Component having a micromechanical microphone structure, at least comprising

   - an acoustically active membrane (11), which functions as a deflectable electrode of a microphone capacitor,

   - a stationary acoustically permeable counterelement (12), which functions as a counterelectrode of the microphone capacitor, and

   - means for detecting and evaluating the changes in capacitance of the microphone capacitor,

   wherein the membrane (11) is realized in a membrane layer (3) above the semiconductor substrate (1) of the component and spans a sound opening (13) in the rear side of the substrate, and
   wherein the counterelement (12) is formed in a further layer (5) above the membrane (11);
   characterized in that said further layer (5) substantially extends over the entire component area and compensates for level differences, such that the entire component surface is largely planar in accordance with said further layer (5).
2. Component according to Claim 1, characterized in that the membrane layer (3) is realized in the form of a thin polysilicon layer, which is electrically insulated from the semiconductor substrate (1) by a first insulation layer (2), and in that the counterelement (12) is formed in a thick epitaxial polysilicon layer (5), which is electrically insulated from the membrane layer (3) by a second insulation layer (4), wherein the layer thickness of said second insulation layer (4) determines the distance between the membrane (11) and the counterelement (12).
3. Component according to either of Claims 1 and 2, characterized in that a spring suspension (14) for the membrane (11) is formed in the membrane layer (3).
4. Component according to Claim 3, characterized in that the spring suspension (14) comprises at least three spring elements which are connected to the semiconductor substrate and/or the counterelement via the first and/or the second insulation layer.
5. Method for producing components according to any of Claims 1 to 4,

   - wherein a first electrically insulating sacrificial layer (2) is applied to a semiconductor substrate (1),

   - wherein a membrane layer (3) is applied to the first sacrificial layer (2) and structured in order to produce at least one membrane (11) with a spring suspension (14) for a respective component,

   - wherein a second electrically insulating sacrificial layer (4) is applied to the structured membrane layer (3),

   - wherein at least one further layer (5) is applied to the second sacrificial layer (4) and structured in order to produce an acoustically permeable counterelement (12) for each membrane (11),

   - wherein at least one sound opening (13) is produced in the rear side of the semiconductor substrate (1) below each membrane (11),

   - wherein the first sacrificial layer (2) and the second sacrificial layer (4) are removed at least in the region below and above each membrane (11) and the spring suspension (14) thereof, and

   - wherein the components are singulated only after the microphone structures have been exposed.
6. Method according to Claim 5, characterized in that a thin polysilicon layer is deposited as membrane layer (3) on the first sacrificial layer (2), and in that a thick epitaxial polysilicon layer (5) is grown on the second sacrificial layer (4), the counterelements (12) being formed in said epitaxial polysilicon layer.
7. Method according to Claim 6, characterized in that the epitaxial polysilicon layer (5) is structured in an anisotropic etching process, in particular in a trench process or in a DRIE process, wherein the second sacrificial layer (4) functions as an etching stop.
8. Method according to any of Claims 5 to 7, characterized in that the sound openings (13) are produced in an anisotropic etching process, in particular in a DRIE process, wherein the first sacrificial layer (2) functions as an etching stop.
9. Method according to any of Claims 5 to 8, characterized in that the first sacrificial layer (2) and the second sacrificial layer (4) are removed in an isotropic etching process, wherein the etching attack is effected via the sound opening (13) and via passage openings (15) in the counterelements (12).
10. Method according to any of Claims 5 to 9, characterized in that the first sacrificial layer (2) and/or the second sacrificial layer (4) are formed from SiO₂ or SiGe.
11. Method according to any of Claims 5 to 10, characterized in that after the microphone structures have been exposed, a protective film (41) is applied to the layer construction (40) above the semiconductor substrate, said protective film preventing particles and liquid from penetrating into the microphone structures, and in that said protective film (41) is removed from the component surface in a manner free of residues after the components have been singulated.
12. Method according to Claim 11, characterized in that a protective film (41) is used which loses its adhesive force as a result of UV irradiation, as a result of a thermal treatment or as a result of a UV irradiation in combination with a thermal treatment.
13. Method according to Claim 12, characterized in that the protective film (41) is laminated onto the largely planar surface of the layer construction (40) under vacuum and is detached from the component surfaces after the singulation process by means of a UV irradiation in combination with a thermal treatment.
14. Method according to any of Claims 11 to 13, characterized in that the components are singulated in a standard sawing process.

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