Method of manufacturing layered structure of MEMS device and MEMS device having such layered structure

Abstract

The present disclosure relates to a method for manufacturing a layered structure of a MEMS device, a layered structure as a layered structure produced by the method, and a MEMS device 200 comprising such a layered structure. For the layered structure or the MEMS device 200, an exemplary starting substrate is used in the manufacturing process that forms a mechanically active functional layer 10, where the mechanically active functional layer 10 comprises a ferroelectric and / or piezoelectric material.

Description

Technical Field

[0001] The present disclosure relates to a method of manufacturing a layered structure of a MEMS device, a layered structure of a MEMS device, and a MEMS device including such a layered structure. Background Art

[0002] A generic method for producing a layered structure for a MEMS device, in particular a piezoelectrically driven MEMS device, as well as a generic layered structure for a MEMS device and a generic MEMS device comprising such a layered structure are known, for example, from US 2009 / 0185253 A1.

[0003] In piezoelectrically driven MEMS devices known in the prior art, for example according to US 2009 / 0185253 A1, the mechanically active functional layer (usually referred to as the device layer) of the layered structure of the MEMS (microelectromechanical system) is usually formed by a non-piezoelectric supporting layer (e.g. silicon), in which the moving or oscillating parts (such as mirror holding support elements and holding spring structures) are formed, for example, by so-called deep reactive ion etching (DRIE).

[0004] During the manufacture of layered structures, the piezoelectric material is usually applied or deposited onto a supporting functional layer. Thus, layered structures (also called MEMS wafers) are used, in which the piezoelectric material must be applied to the subsequent mechanically active structures of the functional layers (e.g. silicon) by additional processing steps during the manufacture and then locally removed again for structuring, e.g. by means of photolithographic masking and etching processes (e.g. subsequent etching of the surfaces not protected by the photoresist of the photolithographic mask).

[0005] All process steps are associated with costs and time. In addition, the growth of the ferroelectric / piezoelectric layer depends on the respective deposition process and the respective growth substrate, so that production-related fluctuations and integration-related limitations occur, which also applies to the piezoelectric coefficient generated by the driven piezoelectric layer.

[0006] Furthermore, the layer thickness of the ferroelectric / piezoelectric layers applied by deposition is limited (typically about 0.5 μm to 5 μm), which also limits the force or torque generation and the electrical drive voltage to be applied (breakdown field strength is typically about 1 MV / cm to 2 MV / cm).

[0007] In view of the above disadvantages, the object of the present disclosure is to provide an improved method for manufacturing a layered structure of a MEMS device based on the above prior art, in particular in a way that saves cost and / or time and / or improves the performance of the produced layered structure. Summary of the invention

[0008] The present disclosure relates to a method for manufacturing a layered structure of a MEMS device, a layered structure manufactured by the method, and a MEMS device including the layered structure, particularly preferably a vacuum-packaged MEMS mirror device.

[0009] In particular, in order to solve the above-mentioned objects, a method for manufacturing a layered structure of a MEMS device and a layered structure manufactured by the method, as well as a MEMS device comprising the layered structure, particularly preferably a vacuum-packaged MEMS mirror device, are proposed according to the independent claims. The dependent claims relate to some exemplary preferred embodiments.

[0010] According to a first aspect, in some embodiments, a method for manufacturing a layered structure of a MEMS device, in particular a MEMS mirror device or a vacuum packaged MEMS mirror device is provided.

[0011] The method of manufacturing a layered structure of a MEMS device exemplarily comprises: providing a starting substrate, which exemplarily comprises at least one functional layer (ie one or more functional layers); and / or structuring at least one functional layer of the starting substrate.

[0012] Preferably, structuring of the at least one functional layer may be performed to form one or more active elements of a MEMS device in the at least one functional layer and / or to form a spring structure in the at least one functional layer, which spring structure preferably holds one or more active elements of a MEMS device.

[0013] In some preferred embodiments, at least one functional layer of the starting substrate may include ferroelectric and / or piezoelectric materials.

[0014] In some embodiments, this is based on the idea that, for example, instead of a silicon substrate, a substrate comprising a ferroelectric and / or piezoelectric material can be used as a starting substrate, and in particular, the starting substrate comprises at least one functional layer comprising a ferroelectric and / or piezoelectric material. In particular, in some embodiments, the starting substrate may preferably comprise one or more ferroelectric and / or piezoelectric layers or one or more functional layers comprising a ferroelectric and / or piezoelectric material.

[0015] In this way, costs and time of many process steps can be saved, in particular deposition processes, for example deposition of the piezoelectric layer, can be avoided.

[0016] Furthermore, the ferroelectric and / or piezoelectric substrate may form at least one functional layer in which the active elements of the MEMS and / or the spring structures holding them may be formed.

[0017] At least one functional layer can preferably form a mechanically active layer and simultaneously drive and / or detect oscillating movements as an actuator and / or sensor.

[0018] In the case of MEMS, "mechanically effective" may here particularly mean that the mechanically effective layer or at least one mechanically effective functional layer (device layer) of the MEMS layered structure preferably forms a layer which is designed or formed according to its structuring to perform oscillatory movements (in particular one-dimensional or two-dimensional oscillatory movements), or so that one or more structures or bodies formed in the mechanically effective layer or the mechanically effective functional layer can perform oscillatory movements, in particular one-dimensional or two-dimensional oscillatory movements (for example, around one oscillation / torsion axis or around two preferably transverse or in particular perpendicular oscillation / torsion axes, for example via a spring structure, for example using a bending spring, a torsion spring and / or a zigzag spring, in particular, for example, for Lissajous scanning movements or preferably resonant Lissajous scanning movements).

[0019] Preferably, a holding structure and / or a spring structure for the movable structure or body of the mechanically active layer or mechanically active functional layer can also be formed in this mechanically active layer or mechanically active functional layer.

[0020] In some embodiments, the retaining structure and / or spring structure may include a spring, particularly preferably a bending spring, a zigzag spring and / or a torsion spring, which may preferably be designed to retain one or more active structures or bodies of a mechanically effective layer or a mechanically effective functional layer, for example so that the active structure or body can perform corresponding oscillatory rotational movements (for example, torsional oscillations) around corresponding axes of one or more corresponding oscillation and / or torsion axes.

[0021] Furthermore, the formation of a mechanically effective layer or a mechanically effective functional layer may preferably determine one or more resonant frequencies, deflection amplitudes and / or any dynamic deformations of the MEMS (e.g. in retaining structures and / or spring structures formed in the mechanically effective layer or the mechanically effective functional layer or in the formed structure or body (such as a mirror support element having a mirror plate)).

[0022] In addition, in some embodiments, the starting substrate or one or more functional layers in the starting substrate can be provided as a ferroelectric and / or piezoelectric single crystal or polycrystal, thereby providing optimal ferroelectric / piezoelectric properties with optimal ferroelectric / piezoelectric coefficients, which cannot be achieved in traditional deposition processes due to process variations and growth conditions.

[0023] In some preferred embodiments, the starting substrate including at least one functional layer may be made of ferroelectric and / or piezoelectric materials.

[0024] In some preferred embodiments, one or more functional layers of the starting substrate may be made of ferroelectric and / or piezoelectric materials.

[0025] Preferably, the starting substrate comprising at least one functional layer may comprise one or more piezoelectric layers of ferroelectric and / or piezoelectric materials, in particular one or more functional layers of ferroelectric and / or piezoelectric materials.

[0026] In some preferred embodiments, the starting substrate including the at least one functional layer and / or the at least one functional layer of the starting substrate may include and / or may consist of single crystals of ferroelectric and / or piezoelectric materials.

[0027] In a further preferred embodiment, the starting substrate comprising the at least one functional layer and / or the at least one functional layer of the starting substrate may comprise and / or consist of a polycrystal of a ferroelectric and / or piezoelectric material.

[0028] Furthermore, in embodiments having a plurality of functional layers in the starting substrate, one or more functional layers of the starting substrate may comprise and / or consist of single crystals of ferroelectric and / or piezoelectric materials, wherein one or more other functional layers of the starting substrate may comprise and / or consist of polycrystals of ferroelectric and / or piezoelectric materials.

[0029] In particular, the starting substrate is preferably not a silicon substrate, and preferably the starting substrate does not comprise silicon, or the starting substrate does not comprise a functional layer comprising silicon.

[0030] In some preferred embodiments, the ferroelectric and / or piezoelectric materials may include aluminum nitride (AlN), aluminum scandium nitride (AlScN), lithium niobate (LiNbO3), lithium tantalate (LiTaO3), lead zirconate titanate (PZT), niobium-doped PZT (PZT-Nb) and / or quartz.

[0031] In some embodiments, the starting substrate including at least one functional layer and / or at least one functional layer of the starting substrate may include and / or consist of at least partially amorphous ferroelectric and / or piezoelectric material.

[0032] The at least partially amorphous (eg (partially) amorphous) ferroelectric and / or piezoelectric material may, for example, comprise or consist of PVDF (polyvinylidene fluoride (CF2-CH2)n).

[0033] In some embodiments having multiple functional layers in a starting substrate, the starting substrate can be provided such that the starting substrate includes, for example, at least one functional layer including or consisting of a ferroelectric and / or piezoelectric single crystal, at least one functional layer including or consisting of a ferroelectric and / or piezoelectric polycrystal, and / or at least one functional layer including or consisting of at least partially amorphous ferroelectric and / or piezoelectric material.

[0034] In some preferred embodiments, the layer thickness of at least one functional layer of the starting substrate comprising ferroelectric and / or piezoelectric material can be substantially greater than or equal to 50 μm, in particular substantially greater than or equal to 100 μm, and / or substantially less than or equal to 1 mm.

[0035] In particularly preferred embodiments having several functional layers comprising ferroelectric and / or piezoelectric material, the layer thickness of each functional layer is preferably substantially greater than or equal to 50 μm, particularly preferably substantially greater than or equal to 100 μm, and / or substantially less than or equal to mm.

[0036] In some preferred embodiments, the method may also include: applying and / or providing a conductive electrode layer on the respective opposite sides (e.g., on the front and back sides) of at least one functional layer (e.g., if the starting substrate includes more than one ferroelectric and / or piezoelectric functional layer, the conductive electrode layer has been applied and / or provided in the starting substrate between adjacent functional layers of the starting substrate); and / or structuring the electrode layer to form a patterned electrode surface on the respective opposite sides (e.g., on the front and back sides) of at least one functional layer.

[0037] In some preferred embodiments, the mirror of the MEMS device can be formed during the structuring of one of the electrode layers, particularly preferably during the structuring of the outer electrode layer or during the structuring of the upper or front electrode layer.

[0038] In a further embodiment, a further mirror layer may also be applied to form a reflective mirror for the MEMS device. The mirror layer may comprise or consist of a metal, such as aluminum. Alternatively or additionally, depending on the field of application or the wavelength range, electrodes and / or mirror layers made of gold, platinum or silver may be used. For example, a mirror layer made of a more expensive metal, such as gold, platinum and / or silver, may be applied to an electrode layer made of a cheaper metal, such as aluminum.

[0039] In some preferred embodiments, when at least one functional layer of the starting substrate is structured, a mirror support element can be formed in at least one functional layer, wherein particularly preferably, a mirror (such as the above-mentioned mirror) can be arranged and / or formed on the mirror support element.

[0040] In some preferred embodiments, in particular when at least one functional layer is structured, a spring structure for holding a reflector support element with a reflector can be formed in at least one functional layer. In particular, in some preferred embodiments, it is preferably formed in such a way that the reflector support element with the reflector is held so that it can oscillate, for example around one or two axes (particularly preferably oscillation and / or torsion axes), for example by a bending spring, a torsion spring and / or a zigzag spring.

[0041] In some embodiments, the spring structure may include a spring, particularly preferably a zigzag spring, a bending spring and / or a torsion spring, which is preferably designed to hold the reflector support element so that the reflector support element can perform an oscillatory rotational movement (e.g. a torsional oscillation) about a corresponding oscillation and / or torsion axis.

[0042] In some embodiments with two axes (particularly two oscillation and / or torsion axes), the mirror support element with the mirror and / or the spring structure are particularly preferably designed for a two-dimensional Lissajous scanning movement or preferably a resonant two-dimensional Lissajous scanning movement of the mirror support element with the mirror.

[0043] In some preferred embodiments, a conductive electrode layer for electrical contact may be formed on the opposite side of at least one functional layer.

[0044] In other preferred embodiments, one of the electrode layers (e.g. the second electrode layer) can be guided to the side of another (first) electrode layer by perforated electroplating in the region of at least one functional layer (particularly preferably in the center and / or lateral regions), preferably in such a way that conductive (first and second) electrode layers for electrical contact can be formed on the same side of the at least one functional layer.

[0045] In particular, at least one second electrode layer of the conductive electrode layers can preferably be guided by perforated electroplating in the region of at least one functional layer from a second side of at least one functional layer to a first side of at least one functional layer on which the first electrode layer of the conductive electrode layers is arranged.

[0046] Particularly preferably, at least the first electrode layer and the second electrode layer can be designed to provide electrical contact of the first electrode layer and the second electrode layer on the same first side of the functional layer by electroplating through holes of the second electrode layer.

[0047] For example, in some preferred embodiments, the (second) electrode layer arranged on the back side of at least one functional layer can be guided by perforated electroplating in an area region of the at least one functional layer (in particular in the center or lateral region) to the front side on which another (first) electrode layer is applied, preferably in such a way that the conductive (first and second) electrode layers can be designed for electrical contact on the front side of at least one functional layer, because preferably, the (second) electrode layer applied to the back side of the at least one functional layer can also be contacted on the front side.

[0048] In some preferred embodiments, the starting substrate may include (eg, exactly one) ferroelectric and / or piezoelectric functional layer.

[0049] In some preferred embodiments, the starting substrate may also include multiple ferroelectric and / or piezoelectric functional layers.

[0050] For example, the starting substrate can comprise two ferroelectric and / or piezoelectric functional layers, particularly preferably with a (second) electrode layer arranged in between. Corresponding (first) electrode layers can be arranged on the top and bottom (outside).

[0051] Furthermore, the starting substrate may comprise, for example, three or more ferroelectric and / or piezoelectric functional layers, wherein corresponding electrode layers may preferably be arranged between adjacent ferroelectric and / or piezoelectric functional layers, particularly preferably in such a way that one, several or each ferroelectric and / or piezoelectric functional layer is arranged between two corresponding (first and second) electrode layers.

[0052] According to a second aspect, in some embodiments, a layered structure is further proposed, which layered structure can preferably be produced, in particular, by a method according to at least one of the preceding exemplary aspects.

[0053] In some preferred embodiments, the layered structure may include: at least one structured functional layer, in which one or more active elements of the MEMS device and / or a spring structure that holds one or more active elements of the MEMS device may preferably be formed.

[0054] In particular, in some embodiments the active element may comprise a mirror support element, to which, exemplarily, a mirror plate and / or a mirror layer may be applied, in particular for reflecting electromagnetic radiation, particularly preferably light in the visible and / or infrared range.

[0055] In some preferred embodiments, at least one functional layer may include ferroelectric and / or piezoelectric materials.

[0056] According to a third aspect, in some embodiments, a MEMS device, in particular a MEMS mirror device or a vacuum packaged MEMS mirror device, is further proposed, the MEMS device comprising a layered structure produced by a method according to at least one of the preceding exemplary aspects.

[0057] In operation, according to some embodiments, such MEMS devices may be configured for periodic movement or oscillation within a frequency range of about 1 Hz to kHz, in embodiments preferably for frequencies substantially less than or equal to 200 kHz, and particularly preferably for frequencies substantially less than or equal to 100 kHz.

[0058] This distinguishes such MEMS devices from so-called oscillating quartz devices, which are designed for frequency ranges in the MHz range.

[0059] Other aspects and examples of embodiments as well as advantages of the above-described aspects and features and more specific embodiments may also be found in the following description and explanation of the accompanying drawings, which should not be construed as limiting in any way. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] Figure 1A An exemplary cross-sectional view showing a layered structure of a MEMS device according to a background example;

[0061] Figure 1B Shown include Figure 1A An exemplary cross-sectional view of a MEMS device with a layered structure is shown;

[0062] Figure 2 An exemplary cross-sectional view showing a layer structure during a manufacturing process of an exemplary manufacturing sequence according to an exemplary embodiment;

[0063] Figure 3 Shown according to Figure 2 an exemplary functional schematic cross-sectional view of the fabricated layered structure;

[0064] Figure 4 shows an exemplary functional schematic cross-sectional view of a layered structure according to another exemplary embodiment;

[0065] Figure 5 Shown including according to Figure 3 An exemplary schematic cross-sectional view of a layered structure MEMS device;

[0066] Figure 6 Shown including according to Figure 4 An exemplary schematic cross-sectional view of a layered structure MEMS device;

[0067] Figure 7An exemplary cross-sectional view of a layer structure during a manufacturing process showing an exemplary manufacturing sequence according to another exemplary embodiment;

[0068] Figure 8 Shown include Figure 7 An exemplary schematic cross-sectional view of a MEMS device of a layered structure is shown;

[0069] Fig. 9 An exemplary cross-sectional view showing a layer structure during a manufacturing process of an exemplary manufacturing sequence according to another exemplary embodiment; and

[0070] Fig.10 Shown include Fig. 9 An exemplary schematic cross-sectional view of a MEMS device of a layered structure is shown.

[0071] Reference numerals list

[0072] 1. Substrate layer

[0073] 2 Passivation layer

[0074] 2b Passivation layer

[0075] 3 Functional layer (device layer)

[0076] 3a Grooves or structured areas of the functional layer

[0077] 4 Piezoelectric layer

[0078] 5 Electrode layer

[0079] 5a Reflector

[0080] 6 Covering elements

[0081] 7 Basic components

[0082] 10 Piezoelectric functional layer (device layer)

[0083] 10a First piezoelectric functional layer

[0084] 10b Second piezoelectric functional layer

[0085] 10c The third piezoelectric functional layer

[0086] 11. First electrode layer (top electrode)

[0087] 11a First electrode layer

[0088] 11b First electrode layer

[0089] 111 Reflector

[0090] 12. Second electrode layer (bottom electrode; counter electrode)

[0091] 12a Second electrode layer (counter electrode)

[0092] 12b Second electrode layer (counter electrode)

[0093] 100MEMS Devices

[0094] 200MEMS devices

[0095] 300MEMS devices

[0096] 400MEMS devices

[0097] 500MEMS Devices DETAILED DESCRIPTION

[0098] Hereinafter, examples or embodiments of the present disclosure are described in detail with reference to the accompanying drawings. The same or similar elements in the drawings may be denoted by the same reference numerals, but may also be denoted by different reference numerals in some cases.

[0099] However, it should be emphasized that the purpose of the present disclosure is by no means limited to or restricted to the embodiments and their features described below, but further includes modifications to the embodiments, in particular modifications covered by modifications of the features of the examples or by a combination of one or more features of the examples within the scope of protection of the independent claims.

[0100] First, refer to Figure 1A and Figure 1B Background examples are described which are intended to facilitate understanding of the embodiments and advantages described below. Figure 1A and Figure 1B The underlying hierarchical structure is not actually known prior art.

[0101] A general layer structure of the prior art and a corresponding production process can be found, for example, in US 2009 / 0185253 A1.

[0102] Even if the reference Figure 1A and Figure 1B The following description relates to background examples and, unless explicitly stated to the contrary, any described technical details and / or features of the method, the manufacturing sequence, the layer structure and in particular the individual steps and / or layers of the layer structure may also relate to corresponding details and / or features of the exemplary embodiments described below.

[0103] Figure 1A An exemplary cross-sectional view of a layered structure of a MEMS device according to a background example is shown. Figure 1B Shown including according to Figure 1A An exemplary cross-sectional view of a layered structure MEMS device of the background example.

[0104] The layer structure comprises, for example, a substrate layer 1, a functional layer 3 applied to the substrate layer 1 (for example using an intermediate passivation layer 2), a piezoelectric layer 4 (for example, a counter electrode having a bottom electrode or a top electrode) applied to the functional layer 3 (for example using an intermediate passivation layer 2b), and an electrode layer 5 applied to the piezoelectric layer 4 or to a region of the functional layer 3.

[0105] The electrode layer 5 exemplarily forms a top electrode of the piezoelectric layer 4 , and exemplarily forms a reflector 5 a in an area (eg, in a middle area) arranged on the functional layer 3 .

[0106] In the following, an example is given according to Figure 1A Explanation of the possible manufacturing process of the layer structure.

[0107] In an exemplary manufacturing process, corresponding passivation layers 2 and / or 2b (exemplary intermediate layers) may be applied to the top and bottom (or front and back) of substrate layer 1. In addition, functional layers 3 (often referred to as device layers) may be applied on substrate layer 1, on the top side of substrate layer 1, with exemplary passivation layers 2 (intermediate layers) in between.

[0108] The substrate layer 1 may for example be made of or comprise silicon.In a suitable embodiment, the substrate layer 1 may for example be provided as a SCS wafer (SCS, "single crystal silicon", for example as a crystalline bulk silicon substrate).

[0109] Furthermore, the substrate layer can also be provided by an SOI wafer (SOI, “Silicon On Insulator”), which may already comprise the substrate layer 1 and, for example, also the functional layer 3 and / or the intermediate layer 2 .

[0110] An exemplary SOI wafer may include a handle wafer which may include, for example, a crystalline bulk silicon substrate, exemplarily followed by an intermediate layer (typically silicon oxide, eg, 100 nm to 2000 nm).

[0111] In other examples, the intermediate layer (eg intermediate layer 2 and / or 2b) may also consist of other (eg dielectric) layers, such as silicon nitride, silicon oxynitride or aluminum oxide. In particular, different intermediate layers may consist of different materials.

[0112] The functional layer 3 (e.g., with a layer thickness of 5 μm to 300 μm) then forms the mechanically active layer. The functional layer 3 can, for example, be made of or include silicon and can, for example, also consist of a pure crystalline substrate (e.g. SCS, “single crystal silicon”) or be applied using an epitaxial deposition process, for example also in polycrystalline form.

[0113] Furthermore, the piezoelectric layer 4 can be applied onto the functional layer 3 , for example with a further interposed passivation layer 2 b . In this case, the electrically conductive layer can preferably be arranged on the underside of the piezoelectric layer 4 , which can serve as a bottom electrode for the piezoelectric layer 4 .

[0114] The piezoelectric layer 4 may preferably include or be formed of a piezoelectric material, preferably having a high piezoelectric and / or ferroelectric constant.

[0115] For example, the piezoelectric layer 4 may include aluminum nitride (AlN), aluminum scandium nitride (AlScN), lead zirconate titanate (PZT), or niobium-doped PZT (PZT-Nb). The piezoelectric layer 4 may also include a semi-crystalline polymer material such as PVDF (polyvinylidene fluoride (CF2-CH2)n).

[0116] Furthermore, the piezoelectric layer 4 , which is applied on or above the functional layer 3 , for example, can be structured in a next or also later process step, particularly preferably by means of a wet and / or dry etching process.

[0117] The remaining area of ​​the piezoelectric layer 4 preferably defines a piezoelectric element and / or a driving and / or sensing element (e.g., an actuator and / or sensor surface) in a subsequent MEMS structure for generating, driving, controlling and / or sensing movement or vibration of a movably held component or element of the MEMS.

[0118] In a further step, for example, an electrode layer 5 can be applied onto the piezoelectric layer 4 (which may optionally have been structured beforehand).

[0119] In a further exemplary step, the electrode layer 5 applied to or over the piezoelectric layer 4 can be structured. In the exemplary step of structuring the electrode layer 5, for example, the desired structure of a top electrode (top electrode) for upper electrical contacting of the piezoelectric layer 4 can be formed.

[0120] Furthermore, in the step of structuring the electrode layer 5 , as an example, a reflective mirror 5 a (eg, a mirror layer having a reflective surface) may be formed in the area of ​​the layer structure (eg, in the center) using the material of the electrode layer 5 .

[0121] In such an example, the electrode layer may comprise a metal, in particular aluminum, so that the surface of the electrode layer 5 already has a reflective surface and is suitable for forming the mirror 5a. For example, the top electrode layer (e.g. made of metal, in particular aluminum) deposited on the entire surface may be structured using a wet-chemical or dry-chemical lithography step, for example using spray lithography, using a lift-off process (wherein the lithography is performed before the metal deposition) or for example using positive photoresist lithography.

[0122] In a further exemplary step, the functional layer 3 may be structured in the area 3a. In particular, the mechanically effective structure of the MEMS device may be formed in the functional layer. This includes, for example, forming or exposing a mirror support element, which may be formed, for example, by a central area of ​​the functional layer 3 (here, for example, the area of ​​the functional layer 3 below the mirror layer 5a) and any retaining webs, which may be formed by the functional layer 3 and may, for example, act as retaining spring structures, and which retaining webs hold the mirror support element so that it may, for example, oscillate around one, two or more oscillation or torsion axes (for example, around one oscillation / torsion axis or around two oscillation / torsion axes, which are preferably transverse to each other or in particular perpendicular to each other, for example via springs of a spring structure, for example using bending springs, torsion springs and / or zigzag springs, in particular, for example, for Lissajous scanning movements or preferably resonant Lissajous scanning movements).

[0123] In some embodiments, the spring structure may include a spring, particularly preferably a bending spring, a zigzag spring and / or a torsion spring, which is preferably designed to hold the reflector support element so that the reflector support element can perform an oscillatory rotational movement (e.g. a torsional oscillation) about a corresponding oscillation and / or torsion axis.

[0124] In the conventional method in the prior art, the so-called deep reactive ion etching (DRIE) is usually used to structure the functional layer 3 so as to form deep trenches in the functional layer 3 (eg, area 3a). For example, deep reactive ion etching can be performed using a photolithography mask to structure the functional layer 3.

[0125] In a further exemplary step, the layer structure can be opened on the back side in order to expose the functional layer 3 on the side opposite to the piezoelectric layer 4 (back side).

[0126] In a further exemplary step, the manufactured layered structure may be arranged in accordance with Figure 1B The vacuum packaged MEMS device 100 is shown in FIG.

[0127] For example, the layered structure can be hermetically sealed from above with a translucent cover element 6 (e.g. a translucent dome element or a glass dome) and / or from below with a base element or substrate element 7 under a vacuum atmosphere (e.g. vacuum packaging). In some further embodiments, it is also possible to provide cover elements of different shapes or 3D shapes (e.g. angular or flat, e.g. also tilted windows or flat windows). The material of the cover element is preferably translucent, e.g. made of glass or other optically transparent material (e.g. about 400 nm to 2500 nm), such as borosilicate glass (e.g. SCHOTT's ). BF33).

[0128] Therefore, if Figure 1B As shown, a vacuum packaged (or vacuum encapsulated) MEMS mirror device 100 (eg, a MEMS mirror scanner) including the fabricated layered structure may be provided with a piezoelectrically driven, deflectable or steerable mirror 5a.

[0129] Various exemplary embodiments are described below. Unless the difference is explicitly stated, any details or exemplary features in the above examples, especially those related to individual process steps and materials, can also be applied similarly to the following embodiments. In addition, unless the difference is explicitly stated, the description of details or exemplary features of the following embodiment examples, especially the description of individual process steps and materials, can also be applied similarly to other embodiment examples.

[0130] Figure 2 An exemplary cross-sectional view of a layer structure during a manufacturing process showing an exemplary manufacturing sequence according to an embodiment example. In further possible embodiments, the order of the steps may also be different, steps may be omitted and / or additional steps may be added.

[0131] In contrast to the above-mentioned background examples, the basic idea of ​​some embodiments is that at least one functional layer which later forms a mechanically active layer of a MEMS device is formed from a piezoelectric and / or ferroelectric material.

[0132] Thus, exemplarily, the mechanically acting functional layer (i.e., one or more layers forming in particular a moving element or an oscillating element of a MEMS) is already ferroelectric and / or piezoelectric, whereby the ferroelectric and / or piezoelectric functional layer also drives the amplitude and / or frequency of movement or vibration in the MEMS - acting as an actuator, and / or detects the amplitude and / or frequency of movement or vibration in the MEMS - acting as a sensor. This means that no further piezoelectric layer needs to be deposited on the functional layer.

[0133] In contrast to the above-mentioned background examples, and in particular in contrast to the prior art, this therefore advantageously allows many manufacturing steps to be saved, including various deposition steps, such as the deposition of the functional layer 3 and the deposition of the piezoelectric layer 4, and also the backside opening or exposure of the functional layer 3 (e.g. through the backside opening of the substrate layer 1 in the above-mentioned background examples). As a result, a lot of cost and time can be saved in the manufacturing process.

[0134] Furthermore, in some embodiments, the starting substrate including the functional layer 3 can be provided as a single-layer or multi-layer piezoelectric single crystal or polycrystal in some embodiments. This enables the piezoelectric performance to be improved or optimized by optimizing the piezoelectric coefficient, in particular compared to previously known methods in which the piezoelectric layer is deposited on the starting substrate in the process.

[0135] Here, a substrate layer 10 of ferroelectric / piezoelectric material can be provided directly (eg, instead of a layer structure having a substrate layer 1 and a functional layer 3), hereinafter referred to as a piezoelectric functional layer 10; see for example Figure 2 (i).

[0136] In some preferred embodiments, the piezoelectric functional layer 10 may be provided as a substrate of a ferroelectric / piezoelectric single crystal or polycrystalline. However, the piezoelectric functional layer 10 may also be at least partially amorphous.

[0137] In some preferred embodiments, the layer thickness of the piezoelectric functional layer 10 may be substantially greater than or equal to 50 μm, preferably substantially greater than or equal to 100 μm, exemplarily even substantially greater than or equal to 200 μm. In embodiments, the piezoelectric functional layer 10 may be provided with a layer thickness substantially greater than or equal to 100 μm and / or substantially less than or equal to 1 mm.

[0138] In some preferred embodiments, the piezoelectric functional layer 10 may include a ferroelectric and / or piezoelectric material, or may be formed of a ferroelectric and / or piezoelectric material preferably having a high piezoelectric and / or ferroelectric constant.

[0139] For example, the piezoelectric functional layer 10 may include aluminum nitride (AlN), aluminum scandium nitride (AlScN), lithium niobate (LiNbO3), lithium tantalate (LiTaO3), lead zirconate titanate (PZT), niobium-doped PZT (PZT-Nb) and / or quartz, or be composed of one of the above materials.

[0140] In a further step, a conductive layer (hereinafter referred to as the first electrode layer 11) can be applied or deposited on one side of the provided piezoelectric functional layer 10; see for example Figure 2 (ii).

[0141] In a further step, the first electrode layer 11 can be structured; see for example Figure 2 (iii). Here, in an embodiment, the upper (front) electrode surface can be formed for deflection of the piezoelectric crystal or the piezoelectric functional layer 10. In the exemplary step of structuring the first electrode layer 11, the desired structure of the upper electrode (top electrode) for the upper (front) electrical contact of the piezoelectric functional layer 10 can be formed.

[0142] In some embodiments, for example when manufacturing a layered structure of a MEMS mirror device, one or more mirrors or mirror plates may also be formed in this step, such as Figure 2 (iii) Mirror 111. For example, in the step of structuring the first electrode layer 11, the material of the electrode layer 11 may be used to form a mirror 111 (eg, a mirror layer having a surface reflecting electromagnetic radiation) in the area of ​​the layer structure (eg, in the center).

[0143] In some embodiments, the first electrode layer 11 may include, for example, a metal, in particular aluminum, such that a surface of the first electrode layer 11 may preferably already have a reflective surface and / or be suitable for forming a reflector 111 .

[0144] For example, a top electrode layer (e.g. made of metal, in particular aluminum) deposited over the entire surface can be structured via a lithography step using wet or dry chemistry (e.g. by spray lithography), or alternatively via a lift-off process (wherein the lithography is performed before the metal deposition). In some embodiments, the electrode layer can also be applied by shadow mask deposition.

[0145] In a further example, a non-reflective electrode layer (or also, for example, a less reflective electrode layer, for example having a reflectivity substantially less than or equal to 60% in the relevant wavelength range) and / or a non-metallic electrode layer (for example doped polysilicon) can be provided, whereby in a further process step a further mirror layer, for example of a metal, can then be applied in the center (for example as a thin metal film) to form a reflector.

[0146] In some preferred embodiments, the material of the (front) metal electrode layer 11 or the mirror layer 111 can be selected according to the desired application in the corresponding wavelength range, in particular having very good reflection behavior in the wavelength range of the desired application (e.g., substantially greater than or equal to 85% in the relevant wavelength range), such as aluminum or silver for visible light (e.g., wavelength substantially 400nm to 700nm), or gold for infrared light or infrared radiation (e.g., wavelength substantially 850nm to 2000nm).

[0147] In a further step, a further conductive layer, hereinafter referred to as the second electrode layer 12 (or counter electrode), may be applied or deposited on the side of the piezoelectric functional layer 10 opposite to the first electrode layer 11 (ie, for example, on the rear side); see for example Figure 2 (iv).

[0148] In some embodiments, the second electrode layer 12 can include, for example, a metal, particularly aluminum.

[0149] For example, a bottom electrode layer (e.g. made of metal, in particular aluminum) deposited over the entire surface can be structured by a photolithography step using wet chemistry or dry chemistry (e.g. by spray lithography), or alternatively using a lift-off process (wherein the photolithography is performed before the metal deposition). In some embodiments, the electrode layer can also be applied by shadow mask deposition.

[0150] In a further example, a non-reflective or non-metallic electrode layer (eg, doped polysilicon) can be provided.

[0151] In a further step, the second electrode layer 12 can be structured; see for example Figure 2 (v). Here, in the implementation example, a lower electrode surface for deflection of the piezoelectric crystal or the piezoelectric functional layer 10 can be formed. In the exemplary step of structuring the second electrode layer 12, the desired structure of the lower electrode (e.g., the rear bottom electrode) for the lower electrical contact of the piezoelectric functional layer 10 can thus be formed. Thus, the structured electrode layer 12 can be used as a counter electrode or a counter electrode surface for the electrode of the first electrode layer 11, for example, for negative potentials.

[0152] In a further step, the piezoelectric functional layer 3 can be structured; see for example Figure 2 (vi). In particular, the mechanically effective structure of the MEMS device can be formed in the functional layer. This includes, for example, forming or exposing a mirror support element, which is formed by a (e.g. central) area of ​​the functional layer 10 (here, for example, the area of ​​the functional layer 10 below the mirror layer 111) and a retaining web, which can be formed by the functional layer 10 and can, for example, act as a retaining spring structure, and which can retain the mirror support element so that it can, for example, oscillate around one, two or more oscillation or torsion axes (e.g., around one oscillation / torsion axis or around two oscillation / torsion axes, which are preferably transverse to each other or in particular perpendicular to each other, for example via a spring of a spring structure, for example using a bending spring, a torsion spring and / or a zigzag spring, in particular, for example, for a Lissajous scanning movement or preferably a resonant Lissajous scanning movement).

[0153] In some embodiments, the spring structure may include a spring, particularly preferably a bending spring, a zigzag spring and / or a torsion spring, which is preferably designed to hold the reflector support element so that the reflector support element can perform an oscillatory rotational movement (e.g. a torsional oscillation) about a corresponding oscillation and / or torsion axis.

[0154] The structuring of the functional layer 10 can be carried out using a wet-chemical or dry-chemical lithography step. In this case, the structuring of the functional layer 10 can be carried out together with the structuring of the second electrode layer 12, or at least with the same mask. In a further embodiment, the structuring of the functional layer 10 can also be carried out independently of the structuring of the second electrode layer 12 and / or with another lithography mask (for example, subsequently etching the surface not protected by the photoresist of the lithography mask).

[0155] In further embodiments, other structuring processes are also possible, for example by laser ablation or also by so-called LIDE processes (laser induced deep etching), in which, for example, in areas of the crystal that have been exposed or irradiated, the crystal is chemically and physically changed so that the etching rate in these areas (for example in wet chemistry) is significantly higher compared to other areas that have not been exposed or irradiated.

[0156] In the above-described embodiments, the electrode layers 11 and 12 may be applied or deposited exemplarily on the respective sides (eg the front and back sides) of the ferroelectric and / or piezoelectric functional layer 10 .

[0157] In a further embodiment, a starting substrate can conveniently already be provided, which includes a ferroelectric and / or piezoelectric functional layer 10 and in which, for example, one or both of the electrode layers 11 and 12 have already been applied, for example bonded to the functional layer 10, or as a laminated composite material, which already includes the functional layer 10 and a first electrode layer 11 and / or a second electrode layer 12.

[0158] Figure 3 An exemplary electrical drive circuit is shown, for example, according to Figure 2 Exemplary schematic functional cross-sectional view of the fabricated layered structure.

[0159] exist Figure 3 , schematically shown, as an example, at least one AC voltage can preferably be applied between at least one electrode of the first electrode layer 11 and at least one electrode of the second electrode layer 12, for example to control (and / or detect) a voltage generation or a voltage drop across the piezoelectric substrate or the piezoelectric functional layer 10. In some further embodiments, several AC voltage sources can also be used for different actuator surfaces (e.g., with different oscillation frequencies in a lateral or vertical torsion or oscillation axis, for example via a spring structure, for example using a bending spring, a torsion spring and / or a zigzag spring, for example for a 2D Lissajous scanning movement or preferably a resonant 2D Lissajous scanning movement of the mirror 111).

[0160] Figure 3 The thin dashed arrow in shows schematically by way of example a controllable or excitable and / or detectable deflection of the piezoelectric functional layer 10 , whereby an oscillation or oscillating movement of a mirror support element of the piezoelectric functional layer 10 arranged below the mirror 111 can be driven and / or detected. Figure 3 The thick dashed arrow in illustratively shows, as an example, the reflection of the light beam on the (oscillating or moving) mirror 111 .

[0161] Figure 4 An exemplary schematic functional cross-sectional view of a layered structure in another exemplary electrical drive circuit according to another exemplary embodiment is shown.

[0162] and Figure 3 In contrast to the example in , in further embodiments, for example, Figure 4 As shown, the second (rear) electrode layer 12 may be plated with holes, wherein at least in an exemplary lateral (or central) region of the functional layer 10, the second electrode layer 12 ( Figure 4 The exemplary second electrode layer on the left in the figure) or at least a portion of the second electrode layer 12 (or an electrode portion electrically connected to the second electrode layer 12) is guided to the side (front side) of the functional layer 10 where the first electrode layer 11 is arranged. Such perforated electroplating can be performed, for example, through or along one or more structured areas of the functional layer 10 (for example, on one or more structured areas of the functional layer 10 or one or more side walls of the structured grooves).

[0163] Conveniently, the electrical contacts of the electrodes of the first electrode layer 11 and the second electrode layer 12 can be arranged on the same side (front side) of the functional layer 10. Thus, the complexity of the MEMS structure, in particular the contact and connection technology, can be simplified. For example, simple wire bonds can be placed on the front side and / or simple solder balls can be provided on the back side.

[0164] On the upper side (front side), it is schematically shown by way of example that at least one AC voltage can preferably be applied between at least one electrode of the first electrode layer 11 and at least one electrode of the second electrode layer 12, wherein exemplary contacts are made on the upper side (front side), for example in order to control (and / or detect) a voltage generation or a voltage drop across the piezoelectric substrate or the piezoelectric functional layer 10. In some embodiments, several AC voltage sources can also preferably be used here for different actuator surfaces (e.g. with different oscillation frequencies in a lateral or vertical torsion or oscillation axis, for example via springs of a spring structure, for example using bending springs, torsion springs and / or meandering springs, for example for a 2D Lissajous scanning movement or preferably a resonant 2D Lissajous scanning movement of the mirror 111).

[0165] Figure 5 An exemplary schematic cross-sectional view of a MEMS device 200 is shown, which exemplarily includes a Figure 3 In this example, the layered structure can be hermetically sealed from above with a translucent cover element 6 (eg, a translucent dome element or a glass dome) and / or from below with a base element or substrate element 7 under a vacuum atmosphere (eg, vacuum packaging).

[0166] Figure 6 An exemplary schematic cross-sectional view of a MEMS device 300 is shown, which exemplarily includes a Figure 4 In this example, the layered structure can be hermetically sealed from above with a translucent cover element 6 (eg, a translucent dome element or a glass dome) and / or from below with a base element or substrate element 7 under a vacuum atmosphere (eg, vacuum packaging).

[0167] In further embodiments, differently shaped covering elements or 3D shaped covering elements are also possible (e.g. angular or planar, e.g. also tilted windows or planar windows). The material of the covering element is preferably translucent, e.g. glass or other optically transparent material (e.g. about 400 nm to 2500 nm), such as borosilicate glass (e.g. SCHOTT's BF33).

[0168] Therefore, an exemplary vacuum-packaged (or vacuum-encapsulated) MEMS mirror device 200 or 300 (e.g., a MEMS mirror scanner) including the manufactured corresponding layered structure may be provided with a piezoelectrically deflectable or controllable mirror 111, which can be used for exemplary 1D and / or 2D scanning movements of the mirror 111 (e.g., 2D scanning movements for Lissajous scanning or preferably resonant 2D scanning movements for Lissajous scanning, i.e., for example, a double resonant mirror 111 with resonant 2D scanning movements for Lissajous scanning, for example, via a spring of a spring structure, for example utilizing a bending spring, a torsion spring and / or a zigzag spring).

[0169] exist Figure 5 and Figure 6 In the example, by attaching to an exemplary base element or substrate element 7, an exemplary fixing of the layered structure is provided (in particular in order to hold the spring structure in the outer region, which holds the reflector support element or reflector 111), which is Figure 3 and Figure 4 It is only schematically shown as an example.

[0170] Figure 7 An exemplary cross-sectional view of a layer structure during a manufacturing process showing an exemplary manufacturing sequence according to another exemplary embodiment. In other possible processes, the order of steps may also be different, steps may be omitted and / or additional steps may be added.

[0171] However, in the above-mentioned embodiments, the corresponding starting substrate is exemplarily provided with a ferroelectric or piezoelectric functional layer 10. In contrast to the above-mentioned embodiments, a method according to Figure 7 (i) An exemplary starting substrate, which exemplary comprises two ferroelectric or piezoelectric functional layers 10a and 10b. The two ferroelectric or piezoelectric functional layers 10a and 10b (or the ferroelectric or piezoelectric layers 10a and 10b forming the functional layers) may comprise the same ferroelectric or piezoelectric material and / or different ferroelectric or piezoelectric materials.

[0172] As an example, the following method may be provided: Figure 7(i) such that a (second) electrode layer 12 (eg, a metal electrode layer) is arranged between two ferroelectric or piezoelectric functional layers 10a and 10b. Figure 7 (i) such that two ferroelectric or piezoelectric functional layers 10a and 10b and an exemplary (second) electrode layer 12 located therebetween are bonded or laminated.

[0173] In accordance with Figure 7 (i) The corresponding (first) electrode layers 11a and 11b are arranged on the opposite outer sides (e.g. the front side and the back side) of the starting substrate. These (first) electrode layers 11a and 11b can, for example, be applied to the starting substrate (e.g. by a deposition process), or can also, for example, be already arranged in the starting substrate (e.g. bonded or laminated to the corresponding functional layer 10a / 10b).

[0174] In accordance with Figure 7 In the exemplary manufacturing process of FIG. 1 , the (first) electrode layer 11a on the top (front side) may also be structured (e.g., similar to Figure 2 (iii) in the electrode layer 11); see for example Figure 7 (ii).

[0175] For example, in a step of structuring the (first) electrode layer 11 a , for example in the center of the layer structure, a mirror 111 , for example a mirror layer having a reflective surface, may be formed from the material of the electrode layer 11 a .

[0176] In some embodiments, the (first) electrode layer 11a may comprise, for example, a metal, in particular aluminum, such that a surface of the (first) electrode layer 11a already comprises, for example, a reflective surface and / or is suitable for forming a reflector 111 .

[0177] In some preferred embodiments, the material of the metal (first) electrode layer 11a or the mirror layer 111 can be selected according to the desired application in the corresponding wavelength range, in particular having very good reflection behavior in the wavelength range of the desired application, such as aluminum or silver for visible light (e.g., wavelength substantially 400nm to 700nm), or gold for infrared light or infrared radiation (e.g., wavelength substantially 850nm to 2000nm).

[0178] In accordance with Figure 7 In the exemplary manufacturing process of Figure 2 (vi) Structuring; see for example Figure 7 (iii).

[0179] The (front side) structuring of the ferroelectric or piezoelectric functional layer 10a can be performed via a photolithography step using wet chemistry or dry chemistry. In some embodiments, the structuring of the ferroelectric or piezoelectric functional layer 10a can be performed together with the structuring of the electrode layer 12, or at least with the same mask.

[0180] In a further embodiment, the structuring of the ferroelectric or piezoelectric functional layer 10a can be performed independently of the structuring of the electrode layers 11a and / or 12 and / or with another lithography mask (e.g., etching downstream of surfaces not protected by the photoresist of the lithography mask). In a further embodiment, other structuring processes are also possible, such as laser ablation of structures or also by so-called LIDE processes (laser induced deep etching).

[0181] In accordance with Figure 7 In an exemplary manufacturing process of , the (first) electrode layer 11b at the bottom (back side) can also be structured; see for example Figure 7 (iv) In some embodiments, the (first) electrode layer 11b may comprise, for example, a metal, in particular aluminum.

[0182] In accordance with Figure 7 In an exemplary manufacturing process of the second ferroelectric or piezoelectric functional layer 10b may also be structured (similar to the functional layer 10a); see for example Figure 7 (v).

[0183] The (back side) structuring of the ferroelectric or piezoelectric functional layer 10b can be performed using a wet-chemical or dry-chemical lithography step. The structuring of the ferroelectric or piezoelectric functional layer 10b can be performed together with the structuring of the electrode layer 12, or at least using the same mask.

[0184] In a further embodiment, the structuring of the ferroelectric or piezoelectric functional layer 10b can be carried out independently of the structuring of the electrode layers 11b and / or 12 and / or with another lithography mask (e.g., subsequent etching of the surface not protected by the photoresist of the lithography mask). In a further embodiment, other structuring methods are also possible, for example by laser ablation or also by the so-called LIDE method (laser induced deep etching).

[0185] In accordance with Figure 7 In an exemplary manufacturing process of , the (second) electrode layer 12 (counter electrode) can also be structured; see for example Figure 7 (vi) In some embodiments, the (second) electrode layer 12 may comprise, for example, a metal, in particular aluminum.

[0186] By structuring the ferroelectric or piezoelectric functional layers, in particular by structuring the ferroelectric or piezoelectric functional layers 10a and 10b (and structuring the electrode layer 12), a mechanically active structure of a MEMS device can be formed in the ferroelectric or piezoelectric functional layers 10a and 10b.

[0187] This comprises, for example, forming or exposing a mirror support element, which is formed by a (e.g. central) region of the ferroelectric or piezoelectric functional layers 10a and 10b (here, for example, the region below the mirror layer 111) and a retaining web, which can be formed by the functional layers 10a or 10b and can, for example, act as a retaining spring structure and which can, for example, retain the mirror support element so that it can oscillate about one, two or more oscillation or torsion axes (e.g. about one oscillation / torsion axis or about two oscillation / torsion axes, which are preferably transverse to each other or in particular perpendicular to each other, for example via a spring structure, for example using a bending spring, a torsion spring and / or a zigzag spring, in particular, for example, for a Lissajous scanning movement or preferably a resonant Lissajous scanning movement).

[0188] In some embodiments, the spring structure may include a spring, particularly preferably a bending spring, a zigzag spring and / or a torsion spring, which is preferably designed to hold the reflector support element so that the reflector support element can perform an oscillatory rotational movement (e.g. a torsional oscillation) about a corresponding oscillation and / or torsion axis.

[0189] In some implementation examples with two or more ferroelectric or piezoelectric functional layers, if necessary or desired depending on the application, a larger deflection and / or a larger force or torque can be advantageously achieved compared to previous implementation examples with one ferroelectric or piezoelectric functional layer. In further implementations with two or more ferroelectric or piezoelectric functional layers, if necessary or desired depending on the application, the drive voltage can be advantageously reduced at a constant deflection angle compared to previous implementations with one ferroelectric or piezoelectric functional layer.

[0190] Preferably, one or more AC voltages may be applied between the (first) electrode layer 11a and the (second) electrode layer 12 (counter electrode) and / or between the (first) electrode layer 11b and the (second) electrode layer 12 (counter electrode), whereby the AC voltages applied to the (first) electrode layers 11a and 11b may be in phase or out of phase with respect to each other, may be controlled at the same or different frequencies and / or may also be at the same or different amplitudes. In some embodiments, several AC voltage sources may also be used for different actuator surfaces (e.g., with different oscillation frequencies in a lateral or vertical torsion or oscillation axis, e.g., via a spring structure, e.g., using a bending spring, a torsion spring and / or a zigzag spring, e.g., for a 2D Lissajous scanning movement or preferably a resonant 2D Lissajous scanning movement of the mirror 111).

[0191] Figure 8 An exemplary schematic cross-sectional view of a MEMS device 400 is shown, which exemplarily includes a Figure 7 Here, the layered structure can also be hermetically sealed from above with a translucent cover element 6 (eg a translucent dome element or a glass dome) and / or from below with a base element or matrix element 7 in a vacuum atmosphere (eg vacuum packaging).

[0192] In further embodiments, differently shaped covering elements or 3D shaped covering elements are also possible (e.g. angular or planar, e.g. also tilted windows or planar windows). The material of the covering element is preferably translucent, e.g. glass or other optically transparent material (e.g. about 400 nm to 2500 nm), such as borosilicate glass (e.g. SCHOTT's BF33).

[0193] Thus, an exemplary vacuum-packaged (or vacuum-encapsulated) MEMS mirror device 400 (e.g., a MEMS mirror scanner) comprising the fabricated layered structure may be provided with a piezoelectrically deflectable or controllable mirror 111, which is exemplary configured for 1D and / or 2D scanning movement of the mirror 111 (e.g., 2D scanning movement for Lissajous scanning or preferably resonant 2D scanning movement, i.e., for example, a dual resonant mirror 111 having two resonant axes for Lissajous scanning, e.g., via a spring of a spring structure, e.g., utilizing a bending spring, a torsion spring and / or a zigzag spring).

[0194] Fig. 9 An exemplary cross-sectional view of a layered structure during a manufacturing process of an exemplary manufacturing sequence according to another exemplary embodiment is shown. Here, only an exemplary starting substrate (see Fig. 9 (i)) and an exemplary finished layer structure (see Fig. 9(ii)) Any intermediate structuring steps of the functional layers and electrode layers can be carried out in various possible ways and sequences analogously to the exemplary embodiments described above.

[0195] In contrast to the above exemplary embodiments, there is provided a Fig. 9 (i) An exemplary starting substrate, which exemplary comprises three ferroelectric or piezoelectric functional layers 10a, 10b and 10c. The three ferroelectric or piezoelectric functional layers 10a, 10b and 10c (or the ferroelectric or piezoelectric layers 10a, 10b and 10c forming the functional layers) may comprise the same ferroelectric or piezoelectric material and / or different ferroelectric or piezoelectric materials.

[0196] As an example, the following method may be provided: Fig. 9 (i) such that the corresponding electrode layer 11b (first electrode layer) or electrode layer 12a (second electrode layer) (e.g., as a metal electrode layer) is arranged between the corresponding adjacent ferroelectric or piezoelectric functional layers. As an example, in some embodiments, the following method can be provided: Fig. 9 (i) such that the ferroelectric or piezoelectric functional layers 10a, 10b and 10c and the exemplary (first and / or second) electrode layers 11b or 12a located therebetween have been bonded or laminated.

[0197] In accordance with Fig. 9 (i) The corresponding electrode layers 11a (first electrode layer) and 12b (second electrode layer) are arranged exemplarily on the opposite outer sides (e.g., front and back sides) of the starting substrate. The electrode layers 11a and 12b can, for example, be applied to the starting substrate (e.g., by a deposition process), or can also, for example, be already arranged in the starting substrate (e.g., bonded or laminated to the corresponding functional layer 10a / 10c).

[0198] The (second) electrode layers 12a and 12b each exemplarily form a counter electrode corresponding to the corresponding (first) electrode layers 10a, 10b and 10c, so that exemplarily, each ferroelectric or piezoelectric functional layer is arranged between the corresponding first electrode layer and the corresponding second electrode layer (corresponding counter electrode). For example, the electrode layers 12a and / or 12b can be structured similarly to the electrode layers 11a and / or 11b. Typically, the electrode layers 11a and / or 12a and / or the electrode layers 11b and / or 12b do not need to be symmetrical.

[0199] In particular, by structuring the ferroelectric or piezoelectric functional layers 10b and 10c (eg, and also structuring the electrode layers 12a and 11b), a mechanically effective structure of a MEMS device can be formed in the ferroelectric or piezoelectric functional layers; see, for example, Fig. 9 (ii).

[0200] This comprises, for example, forming or exposing a mirror support element, which is formed by a (e.g. central) region of the ferroelectric or piezoelectric functional layers 10a, 10b and 10c (here, for example, the region below the mirror layer 111) and a retaining web, which can be formed by the functional layers 10a, 10b or 10c and can, for example, serve as a retaining spring structure, and which retaining web can, for example, retain the mirror support element so that it can oscillate about one, two or more oscillation or torsion axes (e.g. about one oscillation / torsion axis or about two oscillation / torsion axes, which are preferably transverse to each other or in particular perpendicular to each other, for example via springs of a spring structure, for example using bending springs, torsion springs and / or zigzag springs, in particular, for example, for Lissajous scanning movements or preferably resonant Lissajous scanning movements). Generally, the ferroelectric or piezoelectric functional layers 10a, 10b and / or 10c do not have to be structured symmetrically.

[0201] In some exemplary embodiments, the spring structure may include a spring, particularly preferably a bending spring, a zigzag spring and / or a torsion spring, which is preferably designed to hold the reflector support element so that the reflector support element can perform an oscillatory rotational movement (e.g. a torsional oscillation) about a corresponding oscillation and / or torsion axis.

[0202] The respective electrode layers 11a, 12a, 11b and / or 12b may illustratively be made of or include a metal, preferably aluminum, such as either the same metal or different metals.

[0203] In some preferred embodiments, the material of the metal electrode layer 11a or the mirror layer 111 can be selected according to the desired application in the corresponding wavelength range, and in particular has very good reflection behavior in the wavelength range of the desired application, such as aluminum or silver for visible light (e.g., wavelength is substantially 400nm to 700nm), or gold for infrared light or infrared radiation (e.g., wavelength is substantially 850nm to 2000nm).

[0204] Fig.10 An exemplary schematic cross-sectional view of a MEMS device 500 is shown, which exemplarily includes a Fig. 9 The layered structure can be hermetically sealed from above with a translucent cover element 6 (eg a translucent dome element or a glass dome) and / or from below with a base element or matrix element 7 under vacuum atmosphere (eg vacuum packaging).

[0205] In some further embodiments, differently shaped covering elements or 3D shaped covering elements are also possible (e.g. angular or planar, e.g. also tilted windows or planar windows). The material of the covering element is preferably translucent, e.g. glass or other optically transparent material (e.g. about 400 nm to 2500 nm), such as borosilicate glass (e.g. SCHOTT's BF33).

[0206] Thus, an exemplary vacuum-packaged (or vacuum-encapsulated) MEMS mirror device 500 (e.g., a MEMS mirror scanner) comprising the fabricated layered structure may be provided with a piezoelectrically deflectable or controllable mirror 111, which is exemplary configured for (preferably resonant) 1D and / or 2D scanning movement of the mirror 111 (e.g., 2D scanning movement for Lissajous scanning, i.e., for example, a dual-resonant mirror 111 having two resonant axes for Lissajous scanning, e.g., via a spring of a spring structure, e.g., utilizing a bending spring, a torsion spring and / or a zigzag spring).

[0207] In operation, such layered structures with one, two, three or more ferroelectric and / or piezoelectric functional layers for MEMS devices described above as an example or such MEMS devices according to some exemplary embodiments can be configured for periodic movement or oscillation in a frequency range of about 1 Hz to kHz, preferably for frequencies substantially less than or equal to 200 kHz, and particularly preferably for frequencies substantially less than or equal to 100 kHz in the embodiment examples. This distinguishes such MEMS devices from so-called oscillating quartz devices, which are configured for frequencies in the MHz range.

[0208] In the above-described embodiments, there is in particular a basic idea that, for example, a substrate comprising a ferroelectric and / or piezoelectric material, in particular at least one functional layer comprising a ferroelectric and / or piezoelectric material, can be used as a starting substrate instead of a silicon substrate. In particular, in some embodiments, the starting substrate may preferably comprise one or more ferroelectric and / or piezoelectric layers or one or more functional layers comprising a ferroelectric and / or piezoelectric material.

[0209] In this way, costs and time for many process steps can be saved, in particular since deposition processes, for example of piezoelectric layers, can be avoided. Furthermore, the ferroelectric and / or piezoelectric substrate can form at least one functional layer in which the active elements of the MEMS and / or the spring structures holding them can be formed later. The at least one functional layer can preferably form a mechanically active layer and at the same time act as an actuator and / or sensor to drive and / or detect oscillating movements.

[0210] In the context of MEMS, "mechanically effective" may here particularly mean that a mechanically effective layer or at least one mechanically effective functional layer (device layer) of a MEMS layered structure preferably forms a layer which, according to its structuring, is designed or formed to perform one-dimensional or two-dimensional oscillatory movements, or such that one or more structures or bodies formed in the mechanically effective layer or in the mechanically effective functional layer can perform one-dimensional or two-dimensional oscillatory movements (for example, around one oscillation / torsion axis or around two preferably transverse or in particular perpendicular axes, for example via springs of a spring structure, for example using bending springs, torsion springs and / or zigzag springs, in particular for example for Lissajous scanning movements or preferably resonant Lissajous scanning movements).

[0211] Preferably, a holding structure and / or a spring structure for the movable structure or body of the mechanically active layer or mechanically active functional layer can also be formed for this purpose in this mechanically active layer or mechanically active functional layer.

[0212] Furthermore, the formation of a mechanically effective layer or a mechanically effective functional layer may preferably determine one or more resonant frequencies, deflection amplitudes and / or any dynamic deformations of the MEMS (for example, in retaining structures and / or spring structures formed in the mechanically effective layer or the mechanically effective functional layer or in the formed structure or body (such as a mirror support element having a mirror plate 111)).

[0213] Furthermore, in the above-described embodiments, the starting substrate or one or more functional layers in the starting substrate may be provided as a ferroelectric and / or piezoelectric single crystal or polycrystal, thereby providing optimal ferroelectric / piezoelectric performance with optimal ferroelectric / piezoelectric coefficients, which cannot be achieved in conventional deposition processes due to process variations and growth conditions. Furthermore, in some embodiments, a relatively thick ferroelectric / piezoelectric layer may be provided in the starting substrate, advantageously enabling higher force development, compared to prior art techniques in which a ferroelectric / piezoelectric layer is deposited on a silicon substrate.

[0214] In the above exemplary embodiment, the starting substrate comprising at least one functional layer may comprise a ferroelectric and / or piezoelectric material. In the above exemplary embodiment, one or more functional layers of the starting substrate may comprise a ferroelectric and / or piezoelectric material. Preferably, the starting substrate comprising at least one functional layer may comprise one or more piezoelectric layers of ferroelectric and / or piezoelectric material, in particular one or more functional layers of ferroelectric and / or piezoelectric material.

[0215] In the above embodiments, the starting substrate comprising the at least one functional layer and / or the at least one functional layer of the starting substrate may comprise and / or consist of single crystals of ferroelectric and / or piezoelectric material.

[0216] In the above embodiments, the starting substrate comprising the at least one functional layer and / or the at least one functional layer of the starting substrate may comprise and / or may consist of a polycrystal of a ferroelectric and / or piezoelectric material.

[0217] In particular, the starting substrate is preferably not a silicon substrate and preferably the starting substrate does not comprise silicon or a functional layer containing silicon.

[0218] In some of the above-mentioned exemplary embodiments, the ferroelectric and / or piezoelectric materials may include aluminum nitride (AlN), aluminum scandium nitride (AlScN), lithium niobate (LiNbO3), lithium tantalate (LiTaO3), lead zirconate titanate (PZT), niobium-doped PZT (PZT-Nb) and / or quartz.

[0219] In some of the above exemplary embodiments, the starting substrate including at least one functional layer and / or at least one functional layer of the starting substrate may include at least partially amorphous ferroelectric and / or piezoelectric materials and / or consist of at least partially amorphous ferroelectric and / or piezoelectric materials. Here, the (partial) at least partially amorphous (e.g., (partially) amorphous) ferroelectric and / or piezoelectric material may include, for example, PVDF (polyvinylidene fluoride (CF2-CH2)n) or consist of PVDF.

[0220] In some of the above-mentioned embodiments having multiple functional layers in the starting substrate, the starting substrate can be provided so that the starting substrate includes: for example, at least one functional layer including or consisting of a ferroelectric and / or piezoelectric single crystal, at least one functional layer including or consisting of a ferroelectric and / or piezoelectric polycrystal, and / or at least one functional layer including or consisting of a ferroelectric and / or piezoelectric polycrystal, and / or at least one functional layer including or consisting of at least partially amorphous (e.g., (partially) amorphous) ferroelectric and / or piezoelectric material.

[0221] In some of the exemplary embodiments described above, the layer thickness of at least one functional layer of the starting substrate comprising a ferroelectric and / or piezoelectric material can be substantially greater than or equal to 50 μm, in particular substantially greater than or equal to 100 μm, and / or substantially less than or equal to 1 mm. In particularly preferred embodiments with several functional layers comprising a ferroelectric and / or piezoelectric material, the layer thickness of each functional layer is in each case preferably substantially greater than or equal to 50 μm, particularly preferably substantially greater than or equal to 100 μm, and / or substantially less than or equal to mm.

[0222] In some of the above-mentioned exemplary embodiments, in particular when at least one functional layer is structured, a spring structure for holding a reflector support element with a reflector can be formed in at least one functional layer. In particular, in some embodiments it is preferably formed in such a way that the reflector support element with the reflector is held so that it can oscillate, for example around one or two axes (in particular, for example, an oscillation and / or torsion axis), for example via a spring of the spring structure, for example using a torsion spring and / or a zigzag spring.

[0223] In some exemplary embodiments, the spring structure may include, for example, a spring, particularly preferably a bending spring, a zigzag spring and / or a torsion spring, which is preferably designed to hold the reflector support element so that the reflector support element can perform an oscillatory rotational movement (e.g. a torsional oscillation) about a corresponding oscillation and / or torsion axis.

[0224] In some exemplary embodiments with two axes (in particular oscillation and / or torsion axes), the mirror support element with the mirror and / or the spring structure are particularly preferably designed for a (preferably resonant) two-dimensional Lissajous scanning movement of the mirror support element with the mirror.

[0225] Exemplary embodiments of layered structures with multiple layers have been described above. It should be noted that such embodiments should not be construed as being restrictive in the sense that no further intermediate layers may be present in further embodiments. On the contrary, in further embodiments, further layers and / or intermediate layers may be provided, and / or the described layers may be omitted.

[0226] It should be noted that only examples or embodiments of the present disclosure and technical advantages are described in detail above with reference to the accompanying drawings. However, the present disclosure is by no means limited to or confined to the above-mentioned embodiments and their embodiment features or the combination of their descriptions, but further includes modifications to the embodiments, in particular, modifications covered by the features of the examples or by the combination or partial combination of single or several features of the examples within the scope of protection of the independent claims.

Claims

1. A method for manufacturing a layered structure of a MEMS device, in particular a vacuum packaged MEMS mirror device, the method comprising: Providing a starting substrate, the starting substrate comprising at least one functional layer (10; 10a, 10b; 10a, 10b, 10c), wherein the at least one functional layer (10; 10a, 10b; 10a, 10b, 10c) of the starting substrate comprises a ferroelectric and / or piezoelectric material; and The at least one functional layer (10; 10a, 10b; 10a, 10b, 10c) of the starting substrate is structured to form one or more active elements of the MEMS device (200; 300; 400; 500) in the at least one functional layer (10; 10a, 10b; 10a, 10b, 10c) and / or to form a spring structure in the at least one functional layer (10; 10a, 10b; 10a, 10b, 10c), the spring structure holding the one or more active elements of the MEMS device (200; 300; 400; 500).

2. The method according to claim 1, characterized in that The starting substrate comprising the at least one functional layer (10; 10a, 10b; 10a, 10b, 10c) consists of a ferroelectric and / or piezoelectric material.

3. The method according to claim 1 or 2, characterized in that: The starting substrate comprising the at least one functional layer (10; 10a, 10b; 10a, 10b, 10c) comprises one or more piezoelectric layers of ferroelectric and / or piezoelectric material, in particular one or more functional layers (10; 10a, 10b; 10a, 10b, 10c) made of ferroelectric and / or piezoelectric material.

4. The method according to one of the preceding claims, characterized in that The starting substrate comprising the at least one functional layer (10; 10a, 10b; 10a, 10b, 10c) and / or the at least one functional layer (10; 10a, 10b; 10a, 10b, 10c) of the starting substrate comprises and / or consists of single crystals of ferroelectric and / or piezoelectric material.

5. The method according to one of the preceding claims, characterized in that The starting substrate comprising the at least one functional layer (10; 10a, 10b; 10a, 10b, 10c) and / or the at least one functional layer (10; 10a, 10b; 10a, 10b, 10c) of the starting substrate comprises and / or consists of a polycrystal of a ferroelectric and / or piezoelectric material.

6. The method according to one of the preceding claims, characterized in that The ferroelectric and / or piezoelectric materials include aluminum nitride (AlN), aluminum scandium nitride (AlScN), lithium niobate (LiNbO3), lithium tantalate (LiTaO3), lead zirconate titanate (PZT), niobium-doped PZT (PZT-Nb) and / or quartz.

7. The method according to one of the preceding claims, characterized in that The starting substrate comprising the at least one functional layer (10; 10a, 10b; 10a, 10b, 10c) and / or the at least one functional layer (10; 10a, 10b; 10a, 10b, 10c) of the starting substrate comprises and / or consists of at least partially amorphous ferroelectric and / or piezoelectric material.

8. The method according to one of the preceding claims, characterized in that The layer thickness of the at least one functional layer (10; 10a, 10b; 10a, 10b, 10c) of the starting substrate comprising ferroelectric and / or piezoelectric material is substantially greater than or equal to 50 μm, in particular substantially greater than or equal to 100 μm, and / or substantially less than or equal to 1 mm.

9. The method according to one of the preceding claims, characterized in that applying and / or providing conductive electrode layers (11, 12; 11a, 12, 11b; 11a, 12a, 11b, 12b) on respective opposite sides of the at least one functional layer (10; 10a, 10b; 10a, 10b, 10c); and The electrode layers (11, 12; 11a, 12, 11b; 11a, 12a, 11b, 12b) are structured to form patterned electrode surfaces on respective opposite sides of the at least one functional layer (10; 10a, 10b; 10a, 10b, 10c).

10. The method according to claim 9, characterized in that The mirror (111) of the MEMS device is formed in the structuring of one of the electrode layers (11; 11a), in particular in the structuring of the outer electrode layer (11; 11a).

11. The method according to one of the preceding claims, characterized in that during said structuring of said at least one functional layer (10; 10a, 10b; 10a, 10b, 10c) of said starting substrate, forming a mirror support element in said at least one functional layer (10; 10a, 10b; 10a, 10b, 10c), The reflector (111) is arranged and / or formed on the reflector support element.

12. The method according to claim 11, characterized in that During the structuring of the at least one functional layer (10; 10a, 10b; 10a, 10b, 10c), a spring structure is formed in the at least one functional layer (10; 10a, 10b; 10a, 10b, 10c), which spring structure holds the reflector support element with the reflector (111).

13. The method according to claim 12, characterized in that The spring structure is designed so that the reflector support element with the reflector (111) is held so that it can oscillate about one or two axes, in particular an oscillation axis and / or a torsion axis, and is particularly preferably used for two-dimensional Lissajous scanning movement of the reflector support element with the reflector (111).

14. The method according to at least one of claims 9 to 13, characterized in that The conductive electrode layers (11, 12) for electrical contact are formed on opposite sides of the functional layer (10).

15. The method according to at least one of claims 9 to 13, characterized in that At least one second electrode layer (12) of the conductive electrode layers is guided from a second side of the at least one functional layer (10) to a first side of the at least one functional layer (10) by perforated electroplating in the region of the at least one functional layer (10), and a first electrode layer (11) of the conductive electrode layers is arranged on the first side.

16. The method according to claim 15, characterized in that At least the first electrode layer (11) and the second electrode layer (12) are designed to provide electrical contact of the first electrode layer and the second electrode layer (11, 12) on the same first side of the functional layer (10) by electroplating through holes of the second electrode layer (12).

17. The method according to one of the preceding claims, characterized in that The starting substrate comprises a ferroelectric and / or piezoelectric functional layer (10).

18. The method according to one of the preceding claims, characterized in that The starting substrate comprises two ferroelectric and / or piezoelectric functional layers (10a, 10b) with an electrode layer (12) arranged therebetween.

19. The method according to one of the preceding claims, characterized in that The starting substrate comprises three or more ferroelectric and / or piezoelectric functional layers (10a, 10b, 10c), respective electrode layers (12a, 11b) being arranged between adjacent ferroelectric and / or piezoelectric functional layers (10a, 10b, 10c).

20. A layered structure, in particular produced by a method according to at least one of the preceding claims, comprising: at least one structured functional layer (10; 10a, 10b; 10a, 10b, 10c), in which one or more active elements of the MEMS device (200; 300; 400; 500) are formed and / or a spring structure for holding the one or more active elements of the MEMS device (200; 300; 400; 500), The at least one functional layer (10; 10a, 10b; 10a, 10b, 10c) comprises a ferroelectric and / or piezoelectric material.

21. A MEMS device, in particular a MEMS mirror arrangement (200; 300; 400; 500), comprising a layered structure according to claim 20.

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