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

Abstract

The present disclosure relates to a method of manufacturing a layered structure of a MEMS device, a layered structure manufactured by the method, and a MEMS device 200 (300, 400, 500) comprising the layered structure. For the layered structure, a high-temperature curing step is provided during the production process, for example after structuring the functional layer 3. According to the invention, the structured regions and trenches of the functional layer 3, and in particular spring structures formed in the functional layer 3, have smooth sidewalls and / or rounded corners in the regions 3a after the curing step, such that their rupture limits can thus be increased and early rupture of the functional layer 3 during operation of the MEMS device 200 (300, 400, 500) can be avoided.

Description

[0001] manual

[0002] The present disclosure relates to a method of manufacturing a layered structure of a MEMS device, a layered structure manufactured by the method, and a MEMS device including the layered structure. Background Art

[0003] A general method for producing a layered structure of a MEMS device and a general MEMS device comprising a layered structure are known, for example, from US 2009 / 0185253 A1.

[0004] In the processes commonly used in the prior art, in order to structure the mechanically active functional layer (usually referred to as the device layer) of the layer structure of a MEMS (micro-electromechanical system), so-called high-speed etching or deep reactive ion etching (DRIE) is usually used to form deep grooves in the functional layer, in particular, for example, to form or engrave an active or oscillating body and a corresponding spring structure that holds the active or oscillating body in the functional layer. In the field of MEMS device manufacturing, this is sometimes referred to as the Bosch process, because it is based on a process developed by the Bosch company in the 1990s.

[0005] When such dry etching processes are used to structure the movable or oscillating body and the spring structure holding it, damage or inhomogeneities may occur in the functional layer on the etched side walls in the structured region of the functional layer due to the process, in particular so-called scallops (i.e., for example surface ripples, surface nose structures, etc.). Furthermore, the mask used for structuring leads to a direct transfer into the material of the functional layer (usually silicon), so that the produced structures usually exhibit right-angled corners.

[0006] At the locations of surface damage on the side walls of the grooves of the structured functional layer, such as so-called scallops, notches, sidewall breakthroughs or atomic defects, and at right-angled corners formed in the structure, high stresses may occur in the MEMS structure during resonant oscillations, which may lead to premature structural fracture of the functional layer.

[0007] In view of the above-mentioned shortcomings, the purpose of the present disclosure is to provide an improved method for manufacturing a layered structure of a MEMS device based on the above-mentioned prior art, especially to provide a MEMS device including a layered structure, the mechanical acting parts of which have a higher mechanical fracture limit and / or lower fracture sensitivity. 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, in particular 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, in particular a vacuum-packaged MEMS mirror device, are proposed according to the independent claims. The dependent claims relate to some exemplary preferred exemplary embodiments.

[0010] According to the first aspect, in some exemplary 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 proposed, the method comprising: providing a layered structure comprising a substrate layer and / or a functional layer; applying a piezoelectric layer, for example on and / or above the functional layer, in particular on the side of the functional layer opposite to the substrate layer, i.e., particularly preferably on the side of the functional layer opposite to the substrate layer; and / or structuring the piezoelectric layer, for example on and / or above the functional layer, in particular on the side of the functional layer opposite to the substrate layer, for example on and / or above the functional layer, in particular on the side of the functional layer opposite to the substrate layer, i.e., particularly preferably on the side of the functional layer opposite to the substrate layer; and / or structuring the piezoelectric layer, in particular for forming a structured region of the piezoelectric layer.

[0011] In some exemplary embodiments, an electrode layer (bottom electrode layer) may be provided between the functional layer and the piezoelectric layer, the electrode layer may form, for example, a bottom electrode of a metal (e.g., molybdenum) that is in electrical contact with the piezoelectric layer from below. In an exemplary embodiment, the method may include applying the electrode layer to the functional layer before applying the piezoelectric layer, wherein the piezoelectric layer may be applied to the electrode layer. In some exemplary embodiments, the functional layer (e.g., in the doped region) may be at least partially conductive, such that the functional layer may at least partially provide a bottom electrode for the piezoelectric layer.

[0012] In some preferred exemplary embodiments, the method may include structuring the functional layer, particularly preferably to form a structure or structured regions and / or grooves in the functional layer (i.e., for example, grooves surrounding structured regions), particularly preferably optionally by high-speed etching or deep reactive ion etching (DRIE for short).

[0013] In some preferred exemplary embodiments, the method may also include curing the structured region of the functional layer and / or the grooves in the structured region (for example, particularly preferably for at least partially smoothing the side walls of the grooves in the functional layer and / or for rounding the corners of the grooves in the functional layer), preferably at a temperature substantially greater than or equal to 700°C.

[0014] In some preferred exemplary embodiments, curing may be performed on the structured region of the functional layer to at least partially smooth the sidewalls of the trenches in the functional layer and / or round the corners of the trenches in the functional layer.

[0015] Smoothing of the trench sidewalls in the structured region of the functional layer may in particular mean that inhomogeneities and / or surface effects or defects that occur on the sidewalls during the structuring of the functional layer due to the process are reduced, so that after curing a smoother sidewall surface is provided relative to the sidewall surface state after structuring of the functional layer, and even completely smooth and / or crystal defect-free sidewalls may be achieved. Preferably, the sidewall surface may have a roughness of substantially less than or equal to 50 nm after curing, preferably in particular a roughness of substantially less than or equal to 30 nm and particularly preferably in particular a roughness of substantially less than or equal to 10 nm.

[0016] In some preferred exemplary embodiments, the curing of the structured region of the functional layer can be preferably carried out at a temperature substantially greater than or equal to 800° C. In some preferred exemplary embodiments, the curing of the structured region of the functional layer can be carried out at a temperature substantially less than or equal to 1400° C., particularly preferably at a high temperature substantially less than or equal to 1350° C., particularly preferably at a temperature substantially less than or equal to 1250° C. or substantially less than or equal to 1200° C.

[0017] Preferably, in some exemplary embodiments, the temperature during the curing step or preferably the entire manufacturing process should not exceed 1400°C, more preferably 1350°C, since the melting point of silicon is about 1410°C, because the substrate layer and / or the functional layer may generally contain silicon.

[0018] Here, the integration of a high temperature curing step according to some exemplary embodiments (e.g., by hydrogen annealing and / or by sacrificial oxidation) makes it possible to conveniently at least partially smooth any structured or deep-etched sidewalls of the structured functional layer so as to smooth defects and roughness (e.g., surface scallops, surface notches, sidewall breakthroughs or atomic defects, etc.) generated on the surface of the sidewalls during an etching process (e.g., DRIE) and / or also to round off any right-angled corners generated during etching.

[0019] According to exemplary embodiments, this can advantageously lead to a significantly increased stability or improved fracture stability of the layered structure and / or the active element of the MEMS device comprising such a layered structure with an increased fracture limit, in particular a significantly increased stability or improved fracture stability of the spring structure formed by the functional layer with an increased fracture limit, so that premature fracture of the whole can be avoided. Compared to the prior art method without a curing step, according to some exemplary embodiments involving a curing step, the fracture limit of the moving or oscillating part of the functional layer, or in particular the fracture limit of the spring structure formed in the functional layer, can be at least doubled or even increased five or ten times. Compared to the prior art, i.e. when the component is manufactured without curing side walls (i.e. in particular without smooth side walls and / or without rounded corners), where fracture can occur in particular at smaller deflection angles or deflection amplitudes, in particular for the spring structure, the occurrence of fracture of the deflection structure or spring structure can be significantly reduced, and in particular, even in the components manufactured according to the prior art, fracture of the deflection structure or spring structure has occurred at such higher deflection amplitudes or deflection angles, a larger deflection angle or deflection amplitude can be achieved.

[0020] In some preferred exemplary embodiments, the curing of the structured region of the functional layer may preferably include hydrogen annealing, particularly preferably at a temperature substantially greater than or equal to 900°C and / or substantially less than or equal to 1350°C, more preferably at a temperature substantially greater than or equal to 1000°C and / or substantially less than or equal to 1250°C (or exemplarily substantially less than or equal to 1200°C).

[0021] In some preferred exemplary embodiments, the curing of the structured regions of the functional layer may preferably include oxidizing the sidewalls of the grooves in the functional layer, preferably at a temperature substantially greater than or equal to 700° C., in particular at a temperature substantially greater than or equal to 800° C. and / or at a temperature substantially less than or equal to 1250° C. (or exemplarily substantially less than or equal to 1200° C.).

[0022] In some preferred exemplary embodiments, the curing of the structured area of ​​the functional layer may also preferably include removing the oxide layer on the side walls of the grooves formed in the functional layer, for example, particularly preferably removing the oxide layer on the side walls of the grooves formed in the functional layer by etching (for example, etching of a sacrificial oxide layer).

[0023] In some preferred exemplary embodiments, the method may preferably include: applying an electrode layer, preferably after the structured region of the functional layer is cured, to form an electrode structure of the structured region of the piezoelectric layer and / or to form a reflector and / or a mirror layer on one or more structured regions of the functional layer.

[0024] In some exemplary embodiments, the electrode layer can be used as a top electrode of the piezoelectric layer. In some exemplary embodiments, the electrode layer can also be used as a rewiring (wiring) and / or a bonding pad (eg, for electrical connection to a bottom electrode).

[0025] In some preferred exemplary embodiments, the method may preferably include applying a high temperature stable electrode layer to form an electrode structure for the structured region of the piezoelectric layer, preferably before curing the structured region of the functional layer.

[0026] In some exemplary embodiments, the high temperature stable electrode layer can be used as the top electrode of the piezoelectric layer. In some exemplary embodiments, the high temperature stable electrode layer can also be used as a wiring and / or bonding pad (eg, for electrical connection to the bottom electrode).

[0027] In some preferred exemplary embodiments, the material of the electrode layer and / or the high temperature stable electrode layer may include conductive doped silicon, in particular doped polysilicon.

[0028] In some preferred exemplary embodiments, the material of the electrode layer or the high-temperature stable electrode layer may include a high-temperature stable metal, a high-temperature stable metal alloy or a metal compound, particularly preferably a refractory metal, particularly preferably platinum, molybdenum (melting point of about 2623°C) and / or a high-temperature stable molybdenum alloy and / or a molybdenum compound, tungsten (melting point of about 3422°C), and / or a high-temperature stable tungsten alloy and / or a tungsten compound, in particular tungsten titanium and / or tungsten carbide.

[0029] In some preferred exemplary embodiments, the method may further comprise applying a further layer, preferably after curing the structured region of the functional layer, to form a reflector and / or a mirror layer on the structured region or regions of the functional layer.

[0030] In some preferred exemplary embodiments, the method may further include applying a dielectric layer, in particular to at least the structured region of the piezoelectric layer. In some preferred exemplary embodiments, the application of the dielectric layer may occur after the application and / or structuring of the piezoelectric layer. In some exemplary embodiments, the dielectric layer may preferably be applied before the structured region of the functional layer is cured. In some exemplary embodiments, the dielectric layer may also be applied after the structured region of the functional layer is cured.

[0031] In some preferred exemplary embodiments, the structured region of the piezoelectric layer may preferably be or may be encapsulated between a functional layer and a dielectric layer applied to the structured region of the piezoelectric layer, particularly preferably when the application of the dielectric layer occurs before curing of the structured region of the functional layer.

[0032] Conveniently, it is recognized here that providing a layer structure according to some exemplary embodiments in which structured regions of the piezoelectric layer are encapsulated under a high-temperature stable layer (e.g. under a dielectric layer) allows the integration of one or more high-temperature curing steps (such as hydrogen annealing of the deep-etched surface, e.g. at about 1000°C-1250°C, and / or sacrificial oxidation, e.g. etching back the sacrificial oxide layer at about 800°C-1250°C), in particular also in the case of piezoelectric materials with poor high-temperature stability and in particular also in the case of piezoelectric materials with poor chemical resistance, which can be protected by the encapsulation from the influence of aggressive media, such as oxygen (e.g. in a curing step with sacrificial oxidation) and / or hydrogen (e.g. in a curing step with hydrogen annealing).

[0033] Therefore, in some preferred exemplary embodiments, the method may also preferably include: before curing the structured region of the functional layer, and particularly preferably before applying the electrode layer, applying a dielectric layer at least to the structured region of the piezoelectric layer, preferably so that the structured region of the piezoelectric layer is encapsulated between the functional layer and the dielectric layer applied to the structured region of the piezoelectric layer.

[0034] Alternatively or additionally, in some exemplary embodiments, the piezoelectric layer may also be protected by encapsulation under an electrode layer of a high temperature stable material or metal (see some exemplary embodiments with exemplary high temperature stable electrode layer).

[0035] In some preferred exemplary embodiments, the structured region of the piezoelectric layer may preferably be encapsulated between a functional layer and a high temperature stable electrode layer (optionally with an intervening or region intervening dielectric layer) applied to the structured region of the piezoelectric layer, particularly preferably when the application of the high temperature stable electrode layer occurs before the curing of the structured region of the functional layer.

[0036] Therefore, in some preferred exemplary embodiments, the method may also include: applying a high temperature stable electrode layer and / or structuring the high temperature stable electrode layer, particularly preferably before curing the structured region of the functional layer, preferably so that the structured region of the piezoelectric layer is encapsulated between the functional layer and the applied high temperature stable electrode layer (optionally with an inserted or area-inserted dielectric layer).

[0037] In some preferred exemplary embodiments, the method may also include: structuring a region of the dielectric layer and / or opening a region of the dielectric layer, preferably during or before structuring the functional layer, particularly preferably so that the structured region of the piezoelectric layer remains encapsulated between the functional layer and the dielectric layer deposited on the structured region of the piezoelectric layer.

[0038] In some exemplary embodiments where the piezoelectric layer is encapsulated, the material of the piezoelectric layer may include ferroelectric and / or piezoelectric materials, particularly preferably aluminum nitride (AlN), aluminum scandium nitride (AlScN), lead zirconate titanate (PZT) and / or niobium-doped PZT (PZT-Nb).

[0039] In some preferred exemplary embodiments, the method may further include: applying a dielectric layer to at least the structured region of the piezoelectric layer after the structured region of the functional layer is cured. In some preferred exemplary embodiments, the method may further include: structuring a region of the dielectric layer and / or opening a region of the dielectric layer.

[0040] In some exemplary embodiments, the material of the piezoelectric layer may include a high temperature stable ferroelectric and / or piezoelectric material, particularly preferably aluminum nitride (AlN) and / or aluminum scandium nitride (AlScN).

[0041] In some preferred exemplary embodiments, the structured part of the functional layer can include one or more movable elements preferably formed in the functional layer and / or a spring structure preferably formed in the functional layer, wherein the spring structure can particularly preferably hold the one or more movable elements.

[0042] In some preferred exemplary embodiments, one or more active elements of the structured region of the functional layer may comprise a mirror support element, wherein the mirror may preferably be arranged on the mirror support element.

[0043] In some preferred exemplary embodiments, the spring structure of the structured region of the functional layer can hold the mirror support element with the mirror. The spring structure in the functional layer can preferably be designed so that the mirror support element with the mirror is held so that it can oscillate about one or two axes, in particular an oscillation and / or torsion axis, particularly preferably for a two-dimensional Lissajous scanning movement of the mirror support element with the mirror.

[0044] In some exemplary embodiments, the spring structure may include a spring, particularly preferably 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.

[0045] In some preferred exemplary embodiments, structuring of the functional layer may include high-speed etching and / or reactive ion deep etching.

[0046] According to a second aspect, in some exemplary embodiments, a layered structure manufactured by a method according to at least one of the preceding aspects and exemplary embodiments is further proposed.

[0047] In some preferred exemplary embodiments, the layered structure may include: a substrate layer; a structured functional layer; a structured piezoelectric layer, which is preferably located on the side of the functional layer opposite to the substrate layer, i.e., in particular on the side of the functional layer opposite to the substrate layer; and / or a dielectric layer, which is preferably located at least on the structured region of the piezoelectric layer. In some preferred exemplary embodiments, the structured region of the piezoelectric layer may preferably be encapsulated between the functional layer and the dielectric layer, which is preferably applied to the structured region of the piezoelectric layer.

[0048] In some exemplary embodiments, an electrode layer may be provided between the functional layer and the piezoelectric layer, which electrode layer may form a bottom electrode, for example made of a metal (eg molybdenum), which bottom electrode is in electrical contact with the piezoelectric layer from below.

[0049] In some preferred exemplary embodiments, the trenches in the functional layer can preferably be solidified in the structured region of the functional layer, in particular on the side walls of the trenches, and particularly preferably have smooth side walls and / or rounded corners.

[0050] In some preferred exemplary embodiments, the grooves in the functional layer in the structured region of the functional layer may preferably have smooth sidewalls and / or rounded corners, and / or the sidewalls of the functional layer and / or the structured region may have rounded corners.

[0051] In some preferred exemplary embodiments, in the structured region of the functional layer, the surface roughness of the sidewalls of the grooves in the functional layer may be substantially less than or equal to 50 nm, in particular substantially less than or equal to 30 nm, more preferably less than or equal to 10 nm.

[0052] According to a third aspect, in some exemplary embodiments, a MEMS device, in particular a MEMS mirror device or a vacuum-packaged MEMS mirror device, is further proposed, which MEMS device comprises a layered structure manufactured by a method according to at least one of the preceding aspects and exemplary embodiments.

[0053] Other aspects and examples of some exemplary embodiments and advantages of the above-mentioned aspects and features and some more specific exemplary embodiments can 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

[0054] Figure 1 An exemplary flow chart showing a process for fabricating a layered structure of a MEMS device according to a background example;

[0055] FIG. 2A to FIG. 2C Shown based on Figure 1, an exemplary cross-sectional view of a layer structure during a manufacturing process according to an exemplary manufacturing sequence;

[0056] Figure 3 An exemplary flow chart illustrating a process for fabricating a layered structure of a MEMS device according to some exemplary embodiments of the present disclosure;

[0057] FIG. 4A to FIG. 4B Shown based on Figure 3 , an exemplary cross-sectional view of a layer structure during a manufacturing process according to an exemplary manufacturing sequence;

[0058] Figure 5 Shown according to FIG. 4A to FIG. 4B An exemplary cross-sectional view of a MEMS device manufactured by an exemplary manufacturing sequence of FIG.

[0059] FIG. 6A to FIG. 6B Shown based on Figure 3 , an exemplary cross-sectional view of a layer structure during a manufacturing process according to another exemplary manufacturing sequence;

[0060] Figure 7 Shown according to FIG. 6A to FIG. 6B An exemplary cross-sectional view of a MEMS device manufactured by an exemplary manufacturing sequence of FIG.

[0061] Figure 8 An exemplary flow chart showing a method of manufacturing a layered structure of a MEMS device according to some further exemplary embodiments of the present disclosure;

[0062] FIG. 9A to FIG. 9B Shown based on Figure 8 , an exemplary cross-sectional view of a layer structure during a manufacturing process according to an exemplary manufacturing sequence;

[0063] Fig.10 Shown according to FIG. 9A to FIG. 9B An exemplary cross-sectional view of a MEMS device manufactured by an exemplary manufacturing sequence of FIG.

[0064] Fig.11 An exemplary flow chart illustrating a process for fabricating a layered structure of a MEMS device according to some further exemplary embodiments of the present disclosure;

[0065] FIG. 12A to FIG. 12B Shown based on Fig.11 , an exemplary cross-sectional view of a layer structure during the manufacturing process according to an exemplary manufacturing sequence; and

[0066] Fig.13 Shown according to FIG. 12A to FIG. 12C An exemplary cross-sectional view of a MEMS device fabricated according to an exemplary fabrication sequence.

[0067] Reference numerals list

[0068] 1. Substrate layer

[0069] 2 Middle Layer

[0070] 3 Functional layer (device layer)

[0071] 3a Grooves or structured areas in the functional layer

[0072] 4 Piezoelectric layer

[0073] 5 Dielectric layer

[0074] 5a Opening area of ​​dielectric layer

[0075] 6 Electrode layer

[0076] 6a Reflector

[0077] 6b Bonding pad

[0078] 7 Covering elements

[0079] 8 Base element or base element

[0080] 9 Electrode layer (high temperature stability)

[0081] 11 Sacrificial Oxide Layer

[0082] 10 Electrode layer or mirror layer

[0083] 10a Reflector

[0084] 10b Bonding pad

[0085] 100MEMS Devices

[0086] 200MEMS devices

[0087] 300MEMS devices

[0088] 400MEMS devices

[0089] 500MEMS Devices DETAILED DESCRIPTION

[0090] Hereinafter, examples or some exemplary embodiments of the present disclosure are described in detail with reference to the accompanying drawings. The same or similar elements in the accompanying drawings may be represented by the same reference numerals, but may also be represented by different reference numerals at times.

[0091] However, it should be emphasized that the subject matter of the present disclosure is in no way limited to or restricted to the exemplary embodiments and their exemplary features described below, but further comprises modifications to the exemplary embodiments, in particular modifications covered by modifications of the features of the examples or by a combination of single or several features of the examples within the scope of protection of the independent claims.

[0092] With regard to the terms used in the present disclosure, it should be noted that the following partly refers to "high temperature stable" materials or to "high temperature stable" material properties. For the purposes of the present disclosure, the terms "high temperature stable" materials or "high temperature stable" material properties are intended to mean that such materials are able to withstand temperatures greater than or equal to substantially 1200° C., particularly preferably greater than or equal to substantially 1250° C. or substantially greater than 1250° C., and particularly have a melting point greater than or equal to substantially 1200° C., particularly greater than or equal to substantially 1250° C. or substantially greater than 1250° C., particularly preferably greater than or equal to substantially 1400° C.

[0093] First, refer to Figure 1 and FIG. 2A to FIG. 2C Background examples are described which are intended to facilitate understanding of the exemplary embodiments and advantages described below. Figure 1 and FIG. 2A to FIG. 2C The method on which it is based is not actually known prior art. For example, a general prior art method can be found in US 2009 / 0185253 A1.

[0094] Even if the reference Figure 1 and FIG. 2A to FIG. 2C The following description relates to background examples and, unless explicitly indicated to the contrary, any 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 and / or their possible materials that may be described may also relate to corresponding details and / or features of the embodiments described below.

[0095] In particular, it should be noted that Figure 1 Steps S101 to S104 and Figure 2A The manufacturing sequence (i) to (iv) and its description are always used for Figures 3 to 10 An exemplary embodiment of Figure 1 Steps S101 to S103 and Figure 2A The manufacturing sequence (i) to (iii) and the description thereof also apply to Figures 11 to 13 An exemplary embodiment of .

[0096] Figure 1 An exemplary flow chart of a process for fabricating a layered structure of a MEMS device according to a background example is shown, and FIG. 2A to FIG. 2C Shown based on Figure 1 , an exemplary cross-sectional view of a layered structure during a manufacturing process according to an exemplary manufacturing sequence.

[0097] Reference Figure 1 In exemplary step S101 , a layer structure is provided, the layer structure comprising a substrate layer 1 and a functional layer 3 (usually referred to as a device layer). Figure 2A The layer structure shown in (i) is also based on the corresponding exemplary layer structure. Figure 2A The layer structure of (i) exemplarily includes an intermediate layer 2 (eg, a passivation layer), which is exemplarily arranged between a substrate layer 1 and a functional layer 3 , wherein the functional layer 3 is exemplarily formed on the intermediate layer 2 .

[0098] In accordance with Figure 1 In an exemplary step S102 of the method, the piezoelectric layer 4 is applied to the functional layer 3 according to steps S101 and S102, for example, according to Figure 2A The layer structure of (i) thus comprises a piezoelectric layer 4 formed on a functional layer 3, for example, in accordance with Figure 1 In step S102 , the piezoelectric layer 4 is applied to the layer structure above the functional layer 3 .

[0099] In accordance with Figure 1 In another exemplary step S103 of the method, as an example, the piezoelectric layer 4 applied on or above the functional layer 3 is structured; see also Figure 2A (ii).

[0100] In accordance with Figure 1 In another exemplary step S104 of the method, a dielectric layer 5 is applied by way of example; see also Figure 2A (iii) According to Figure 2A (iii), the dielectric layer 5 is applied to exemplary regions of the piezoelectric layer 4 and further to exemplary regions of the functional layer 3 which are opened after structuring of the piezoelectric layer 4 .

[0101] In some exemplary embodiments, the applied dielectric layer 5 may be opened in selected areas. Figure 2A (iv) For example, in the region 5b the dielectric layer 5 is opened towards the functional layer 3, in particular before application of an electrode layer (see further below), to provide a region 5b intended for a subsequent bonding pad.

[0102] It should be noted that the above aspects and features of the background example are also similarly related to the initial manufacturing steps of the exemplary embodiment described later. Figure 4A , Fig. 6A and Fig. 9AAll later described exemplary embodiments of the manufacturing sequence of Figure 2A One or more of steps (i) to (iv) of the method.

[0103] Refer again Figure 1 In another exemplary step S105 of the method, the electrode layer 6 is applied to the dielectric layer 5, which may optionally have been previously opened in an area (eg, an opening area 5b for a subsequent bonding pad); see also Figure 2A (v) Here, when the electrode layer 6 is applied, the regions 5 b previously opened in the dielectric layer 5 are also filled with the material of the electrode layer 6 , for example, to form bonding pads.

[0104] In accordance with Figure 1 In another exemplary step S106 of the method, the electrode layer 6 applied on or above the dielectric layer 5 is structured by way of example; see also Figure 2A (vi). Here, for example, a bonding pad 6 b is formed with the material of the electrode layer 6 in the region 5 b opened in the dielectric layer 5, which provides electrical contact with the upper side of the functional layer 3 (and / or in some exemplary embodiments, with a bottom electrode on the lower side of the structured region that can be electrically connected to the piezoelectric layer 4).

[0105] In the exemplary step S106 of structuring the electrode layer 6, a desired structure of an upper electrode (top electrode) for upper electrical contact of the piezoelectric layer 4 is formed. In addition, in the exemplary step S106 of structuring the electrode layer 6, according to Figure 2A (vi) A reflective mirror 6a (eg, a mirror layer having a reflective surface) is formed by the material of the electrode layer 6 in the center of the layer structure.

[0106] In such an example, for example, the electrode layer may comprise a metal, in particular aluminum, so that the surface of the electrode layer 6 already has a reflective surface and is suitable for forming the mirror 6a. In a further example, a non-reflective or non-metallic electrode layer (e.g. doped polysilicon) can be provided, in which case a further layer, for example a metallic mirror layer (e.g. as a thin metal film, for example with a layer thickness substantially greater than or equal to 100 nm and / or substantially less than or equal to 2000 nm) may be applied in the region of the layer 6a.

[0107] In accordance with Figure 1 In another exemplary step S107 of the method, the dielectric layer 5 is opened in the region 5a toward the functional layer 3, as also shown in FIG. Figure 2B (vii) In particular, these are the regions 5a of the dielectric layer 5 to be opened, in which the underlying functional layer 3 is structured to form the mechanically active structure of the MEMS device.

[0108] In the context 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, according to its structuring, is designed or formed to perform oscillatory movements (in particular one-dimensional or two-dimensional oscillatory movements), or such 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, in particular for example for Lissajous scanning movements).

[0109] Preferably, a holding structure and / or a spring structure for the movable structure or body of the mechanically effective layer or mechanically effective functional layer can also be formed in the mechanically effective layer or mechanically effective functional layer for this purpose. In some exemplary embodiments, the spring structure can include a spring, particularly preferably a bending spring and / or a torsion spring, which is preferably designed to hold the mirror support element so that the mirror support element can perform an oscillating rotational movement (e.g. torsional oscillation) around a corresponding axis around a corresponding oscillation and / or torsion axis.

[0110] Furthermore, the formation of a mechanically effective layer or a mechanically effective functional layer may preferably determine one or more of the 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).

[0111] In accordance with Figure 1 In another exemplary step S108 of the method, the functional layer 3 is structured in the region 3a, see also Figure 2B (viii). In particular, the mechanically effective structure of the MEMS device is formed in the functional layer. This includes, for example, forming or exposing a mirror support element (here, for example, a region of the functional layer 3 located below the mirror layer 6a), which is formed, for example, by a central region of the functional layer 3 and any retaining webs, which are formed by the functional layer 3, whereby the retaining webs, for example, act as spring structures and can retain the mirror support element so that it can oscillate around one, two or more oscillation or torsion axes.

[0112] In the conventional method in the prior art, so-called deep reactive ion etching (DRIE) is usually used to structure the functional layer 3 in step S108 so as to form a structure on the functional layer 3 (eg Figure 2B A deep trench is formed in region 3a) in (viii). This is sometimes referred to as the Bosch process in the field of MEMS device manufacturing, as it is based on a process developed by the Bosch company in the 1990s.

[0113] When such a dry etching process is used to structure the oscillating body and the holding spring structure in the functional layer 3, damage or inhomogeneities may occur on the etched sidewalls in the structured region of the functional layer due to the process, in particular so-called scallops (i.e. surface ripples, surface notches, etc.; see, for example, Figure 2B (ix)) or, for example, any sidewall breakthroughs and / or atomic defects. Furthermore, the mask used for structuring results in a direct transfer into the material of the functional layer 3 (usually silicon), so that the structures produced can generally have right-angle corners.

[0114] At the locations of surface damage on the side walls of the grooves of the structured functional layer 3, such as scallops, side wall breakthroughs and atomic defects, and at the right-angled corners formed, high stresses may occur during the resonant oscillation, which may lead to premature fracture of the structure of the functional layer 3. In the exemplary embodiment described below, these disadvantages can be conveniently avoided. Compared with the prior art, i.e. when the component is manufactured without solidified side walls (i.e. in particular without smooth side walls and / or without rounded corners), wherein fracture can occur in particular at smaller deflection angles or deflection amplitudes, the occurrence of fracture of the deflection structure or spring structure can be significantly reduced, and in particular, even if fracture of the deflection structure or spring structure has already occurred in the component manufactured according to the prior art, larger deflection angles and deflection amplitudes can be achieved.

[0115] In accordance with Figure 1 In another exemplary step S109 of the method, the layer structure is exemplarily opened on the rear side so as to expose the functional layer 3 on the side opposite to the piezoelectric layer 4; see also Figure 2B (ix), wherein the substrate layer 1 is exemplarily open on the rear side toward the intermediate layer 2, and Figure 2B (x), wherein the intermediate layer 2 is open, for example, on the rear side toward the functional layer 3 .

[0116] In accordance with Figure 1 In another exemplary step S110 of the method, the manufactured layer structure is arranged according to Figure 2B (xi) In the vacuum packaged MEMS device 100. Here, for example, the layered structure is hermetically sealed from above with a semi-transparent dome member 7 (eg, a glass dome) and from below with a base member 8 in a vacuum atmosphere.

[0117] Thus, a vacuum packaged MEMS mirror device 100 (eg, a MEMS mirror scanner) comprising the fabricated layered structure may be provided with a piezoelectrically deflectable or controllable mirror 6a, for example, see Figure 2B (xi).

[0118] 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 exemplary embodiments. In addition, unless the difference is explicitly stated, the description of details or exemplary features of the following exemplary embodiments, especially the description of individual process steps and materials, can also be applied similarly to other exemplary embodiments.

[0119] In contrast to the above examples, some exemplary embodiments preferably provide for a curing step, in particular for curing the structured regions of the functional layer, preferably at a temperature substantially greater than or equal to 700°C.

[0120] In some preferred exemplary embodiments, the structured region of the functional layer may be cured in order to at least partially smooth the sidewalls of the grooves in the functional layer and / or to round the corners of the grooves in the functional layer. Smoothing of the groove sidewalls in the structured region of the functional layer may particularly mean that inhomogeneities and / or surface effects or defects that occur on the sidewalls during the structuring of the functional layer due to the process are reduced, so that after curing a smoother sidewall surface is present relative to the sidewall surface state after structuring of the functional layer, until a possibly completely smooth and / or crystal defect-free sidewall is achieved. Preferably, the sidewall surface may have a roughness of substantially less than or equal to 50 nm after curing, preferably in particular substantially less than or equal to 30 nm and particularly preferably in particular substantially less than or equal to 10 nm.

[0121] In some preferred exemplary embodiments, the curing of the structured region of the functional layer can preferably be carried out at a temperature substantially greater than or equal to 800° C. In some preferred exemplary embodiments, the curing of the structured region of the functional layer can be carried out at a temperature substantially less than or equal to 1400° C., particularly preferably at a high temperature substantially less than or equal to 1350° C. Preferably, in some exemplary embodiments, the temperature in the curing step or preferably the temperature during the entire manufacturing process should not exceed 1400° C., more preferably 1350° C., because the melting point of silicon is about 1410° C., and the substrate layer and / or the functional layer can generally contain silicon.

[0122] Figure 3 An exemplary flow chart illustrating a process for fabricating a layered structure of a MEMS device according to some exemplary embodiments of the present disclosure is shown.

[0123] For example, according to Figure 3 The initial step of the process corresponds to Figure 1 Steps S101 to S104 of the process or according to Figure 2A An exemplary manufacturing sequence (i) to (v) of Figure 2A(v) Afterwards, FIG. 4A to FIG. 4B Shown based on Figure 3 , an exemplary cross-sectional view of a layer structure during a manufacturing process according to an exemplary manufacturing sequence.

[0124] Reference Figure 3 and Figure 2A (i) to (v), in exemplary step S301 (e.g., similar to Figure 1 In step S101 of the present invention, a layer structure including a substrate layer 1 and a functional layer 3 is provided. In exemplary step S302 (e.g., similar to Figure 1 In S102 ), the piezoelectric layer 4 is applied to the functional layer 3 .

[0125] In some exemplary embodiments, the substrate layer 1 may, for example, be formed of silicon or include silicon. In some preferred exemplary embodiments, the substrate layer 1 may, for example, be provided as an SCS wafer (SCS, single crystal silicon), i.e., for example, as a crystalline bulk silicon substrate. In addition, the substrate layer may also be provided by an SOI wafer, which may already include a substrate layer 1 and, for example, also include a functional layer 3 and / or an intermediate layer 2. The SOI wafer may include a handle wafer, which may, for example, consist of a crystalline bulk silicon substrate, exemplarily followed by an intermediate layer (typically, for example, about 100nm-2000nm of silicon oxide), but may also consist of other preferred dielectric layers, such as silicon nitride, silicon oxynitride or aluminum oxide. In particular, different intermediate layers may consist of different materials.

[0126] In some exemplary embodiments, the intermediate layer 2 can therefore be provided as silicon oxide (especially silicon dioxide), or at least include silicon oxide (especially silicon dioxide). The intermediate layer 2 can then be produced, for example, by wet and / or dry oxidation. In some exemplary embodiments, the intermediate layer 2 can also additionally or alternatively include silicon nitride (for example Si3N4), aluminum oxide (for example Al2O3) and / or silicon oxynitride (for example SiON).

[0127] The functional layer 3 (device layer) can be made of silicon or include silicon, for example. In some exemplary embodiments, the functional layer 3 can have a layer thickness of substantially 5 μm-300 μm. In some exemplary embodiments, the functional layer 3 can be present as a pure crystalline substrate, particularly preferably as a single crystal (e.g. SCS), or in some further exemplary embodiments, it can be applied by an epitaxial deposition process, in particular in polycrystalline form (polycrystalline).

[0128] In some exemplary embodiments, an electrode layer may be provided between the functional layer 3 and the piezoelectric layer 4 , which electrode layer may form a bottom electrode, for example made of a metal such as molybdenum, which is in electrical contact with the piezoelectric layer from below.

[0129] In preferred exemplary embodiments, such an exemplary bottom electrode layer below the piezoelectric layer 4 can be designed to be stable at high temperatures, for example as doped polysilicon. In some further exemplary embodiments, the functional layer 3 itself can include doped polysilicon, or at least be formed of doped polysilicon in the region of the subsequently structured piezoelectric layer 4. In some exemplary embodiments, the functional layer 3 can on the one hand form a mechanically active element (e.g. a mirror support element and / or a retaining structure or a spring structure) and can also serve as a high-temperature stable base electrode for the piezoelectric layer 4.

[0130] The piezoelectric layer 4 may preferably include or be formed of a piezoelectric material preferably having high piezoelectric, thermal and / or ferroelectric constants.

[0131] In some preferred exemplary embodiments, the piezoelectric layer 4 may include, for example, aluminum nitride (AlN), aluminum scandium nitride (AlScN), lead zirconate titanate (PZT) and / 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).

[0132] In another exemplary step S303 (e.g., similar to Figure 1 In S103 ), the piezoelectric layer 4 applied to the functional layer 3 or above is structured, particularly preferably by a wet and / or dry etching process.

[0133] In some exemplary embodiments, the remaining area of ​​the piezoelectric layer 4 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 oscillation of a movably held component or element of the MEMS.

[0134] In another exemplary step S304 (e.g., similar to Figure 1 In step S104), a dielectric layer 5 is applied by way of example. The dielectric layer 5 is applied to exemplary regions of the piezoelectric layer 4 and further to exemplary regions of the functional layer 3 which are open after the structuring of the piezoelectric layer 4.

[0135] The dielectric layer 5 may, for example, include silicon oxide, in particular SiO2, or be formed of silicon oxide (in particular SiO2). In a further exemplary embodiment, the dielectric layer 5 may include silicon nitride (e.g. Si3N4) and / or aluminum oxide (Al2O3), oxynitride and / or silicon oxynitride (e.g. SiON) or be formed of it.

[0136] In some exemplary embodiments, the applied dielectric layer 5 may be opened in selected areas, for example by wet and / or dry etching, for example to provide areas 5b, which may be provided for subsequent bonding pads. In some exemplary embodiments, the applied dielectric layer 5 may also be opened or partially opened on the structured areas of the piezoelectric layer 4.

[0137] According to Figure 1 Compared to the order of background examples, Figure 3 In the method, by way of example, the application of the electrode layer has not yet taken place before the structuring of the functional layer 3, so that a curing step is preferably carried out at an elevated temperature of above about 700° C. (i.e. a temperature substantially greater than or equal to 700° C.) up to possibly about 1250° C. (i.e. a temperature substantially less than or equal to 1250° C.), which curing step may follow the structuring of the functional layer 3, electrode layers applied in a conventional manner (e.g. made of aluminum (melting point of about 660° C.)) being unable to withstand these temperatures.

[0138] In accordance with Figure 3 In another exemplary step S305 of the method (e.g., similar to Figure 1 In step S107), the dielectric layer 5 is opened in the regions 5a towards the functional layer 3. In particular, these are the regions 5a of the dielectric layer 5 to be opened, wherein the underlying functional layer 3 is structured to form a mechanically effective structure of the MEMS device.

[0139] In some particularly preferred exemplary embodiments, it can be provided here by way of example that the remaining area of ​​the piezoelectric layer 4 is indeed further completely encapsulated by the dielectric layer 5 (see, for example, Figure 4A (v) and Fig. 6A (v)), ie, as an example, the remaining area of ​​the piezoelectric layer 4 is or does remain completely encapsulated between the functional layer 3 and the dielectric layer 5 .

[0140] Conveniently, the layer structure can still withstand high temperature processes (e.g., above about 700° C. to 1250° C.) without adversely affecting the packaging area of ​​the piezoelectric layer 4. For example, in some exemplary embodiments, this can be conveniently achieved by performing one or more curing steps at an elevated temperature of greater than or equal to 700° C., such as the sacrificial oxidation process described further below, for example, at about 800° C.-1250° C. (see, for example, according to FIG. 4A to FIG. 4B ), and / or hydrogen annealing, for example, at about 1000° C. to 1250° C. (see, for example, FIG. 6A to FIG. 6B ).

[0141] For example, it is recognized that such encapsulation of the structured region of the piezoelectric layer 4 (e.g., by a dielectric layer) advantageously protects the structured region of the piezoelectric layer 4 despite the high temperatures during the curing step and despite the presence of a chemically aggressive medium (e.g., oxygen or hydrogen), so that even piezoelectric materials that are not stable or chemically stable at high temperatures (such as PZT) can be used as piezoelectric materials (encapsulated during the curing step). In some exemplary embodiments using high temperature stable and / or chemically resistant piezoelectric materials, it is not necessary to encapsulate the structured region of the piezoelectric layer 4.

[0142] In accordance with Figure 3 In another exemplary step S306 of the method (e.g., similar to Figure 1 In step S108), the functional layer 3 is structured in the region 3a, see also Figure 4A (v) In particular, the mechanically active structure of the MEMS device is preferably formed in the functional layer 3 by high-speed etching or deep reactive ion etching (DRIE for short).

[0143] Structuring the functional layer 3 comprises, for example, forming or exposing a mirror support element formed by the functional layer 3 (beneath the subsequently applied mirror layer 6a, see, for example, Figure 5 ) and a retaining web (spring structure), which is formed by the functional layer 3 and acts as a retaining spring structure, and the retaining web can retain the reflector support element so that it can oscillate around one, two or more oscillation and / or torsion axes. In some exemplary embodiments, the spring structure may include a spring, particularly preferably a bending spring and / or a torsion spring, which is preferably designed to retain the reflector support element so that the reflector support element can perform an oscillating rotational movement (e.g. torsional oscillation) around the corresponding axis around the corresponding oscillation and / or torsion axis.

[0144] In some exemplary embodiments, for example, reactive ion deep etching for structuring the functional layer 3 may be performed using a photolithography mask.

[0145] The partial opening of the dielectric layer 5 can be performed separately in advance or in the same step using the same photolithography mask. For example, the photolithography mask can then be removed using a plasma or wet chemical process.

[0146] In general, all structuring steps of the present disclosure may be performed using a photolithographic mask that may be removed using plasma or wet chemical processes.

[0147] In accordance with Figure 3In another exemplary step S307 of the method, an exemplary curing step is performed at a high temperature substantially greater than or equal to 700° C. to smooth the sidewalls of the region 3 a of the functional layer 3 etched deep in step S306 and to round the corners of the region 3 a of the functional layer 3 .

[0148] In some exemplary embodiments, the curing step S307 may include a step of oxidizing the surface of the region 3a of the functional layer 3 at an oxidation temperature (e.g., a temperature substantially greater than or equal to 700°C, particularly substantially greater than or equal to 800°C or higher, and optionally preferably substantially less than or equal to 1250°C); for example, see Figure 4A (vi) An exemplary oxide layer 11 is shown.

[0149] For example, according to Figure 4A and Figure 4B In the manufacturing sequence of , after the structuring S306 of the functional layer 3, a sacrificial oxidation is performed according to S307 as a curing step (see for example Figure 4A (vi)).

[0150] By the exemplary oxidation or sacrificial oxidation in the curing step S307, surface effects or surface defects (for example, unevenness, such as formed noses, waves, so-called fan-shaped depressions, etc., and other surface defects such as crystal defects, etching, side wall breakthroughs or atomic defects, etc.) generated on the side walls of the deep etching side walls of the region 3a of the functional layer 3 during etching can be oxidized.

[0151] After the sacrificial oxidation, the sacrificial oxide layer 11 can be selectively removed in the curing step S307, and in the curing step S307, after the sacrificial oxide layer 11 is selectively removed, the smooth sidewalls of the region 3a of the functional layer 3 are still retained, wherein the unevenness and rounded corners of the sidewalls are reduced; for example, see Figure 4A (vii).

[0152] In particular, etch scallops and other surface defects (e.g., crystal defects, etching, sidewall penetration, atomic defects, etc.) can be reduced or eliminated, resulting in smooth sidewalls, possibly even a complete transformation into completely smooth and / or crystal defect-free sidewalls. In addition, right-angled structure corners produced during structuring of the functional layer can be rounded (rounded or radiused structure corners).

[0153] After the corresponding curing step S307, the corresponding layer structure or the MEMS device including the layer structure has smooth sidewalls on the structured areas and grooves of the functional layer, with reduced inhomogeneity, and even has smooth and / or crystal defect-free (e.g. completely smooth) sidewalls and rounded corners, so that the fracture limit of the moving or oscillating part of the functional layer or in particular the spring structure formed in the functional layer can be significantly improved, and the occurrence of premature fracture of the spring structure can be successfully reduced. Compared with the prior art, that is, when the component is manufactured without curing the sidewalls (i.e. in particular without smooth sidewalls and / or without rounded corners), where fracture may have occurred in particular at smaller deflection angles or deflection amplitudes, the occurrence of fracture of the deflection structure or spring structure can be conveniently significantly reduced, and in particular, larger deflection angles or deflection amplitudes can also be achieved, at which larger deflection angles or deflection amplitudes, fracture of the deflection structure or spring structure has already occurred in the component manufactured according to the prior art.

[0154] In accordance with Figure 3 In another exemplary step S308 of the method, an electrode layer 6 is applied after the curing step S307; see also Figure 4A (viii) Here, for example, the region 5 b previously opened in the dielectric layer 5 is also filled with material of the electrode layer, in particular in order to form a bonding pad.

[0155] In some preferred exemplary embodiments, the top electrode layer 6 can be deposited over the entire surface, for example made of metal, in particular for example aluminum. In further exemplary embodiments, high temperature stable materials, in particular for example high temperature stable metals, can also be used for the electrode layer. In some exemplary embodiments, the curing step can also be carried out after the electrode layer has been applied and / or structured, and optionally after the layer structure (which preferably comprises a high temperature stable and chemically resistant material) has been opened on the back side; for example, see below according to Figures 8 to 10 Exemplary embodiments are described.

[0156] In accordance with Figure 3 In another exemplary step S309 of the method, the electrode layer 6 applied on or above the dielectric layer 5 is structured by way of example; see also Figure 4B (ix). Here, for example, a bonding pad 6 b can also be formed with the material of the electrode layer 6 in the region 5 b in which the dielectric layer 5 has been opened, which provides electrical contact with the upper side of the functional layer 3 (and / or in an exemplary embodiment with a bottom electrode which can be electrically connected to the lower side of the structured region of the piezoelectric layer 4).

[0157] In the exemplary step S309 of structuring the electrode layer 6, a desired structure of an upper electrode (top electrode) for upper electrical contact of the piezoelectric layer 4 is formed. In addition, in the exemplary step S309 of structuring the electrode layer 6, according to Figure 4B (iv) A reflecting mirror 6a (mirror layer having a reflecting surface) is formed by the material of the electrode layer 6 in the center of the layer structure.

[0158] In some exemplary embodiments, for example, the electrode layer may comprise a metal, in particular aluminum, so that the surface of the electrode layer 6 already has a reflective surface and is suitable for forming a reflector 6a. In some preferred exemplary embodiments, the top electrode layer (e.g. a metal, such as in particular aluminum) deposited on the entire surface may be structured via a lithography step using wet chemistry and / 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 exemplary embodiments, the electrode layer may also be applied by shadow mask deposition.

[0159] In some exemplary embodiments, a non-reflective or non-metallic electrode layer (e.g. doped polysilicon) can be provided, in which case a further layer, e.g. a metal mirror layer (e.g. as a thin metal film, e.g. with a layer thickness substantially greater than or equal to 100 nm and / or substantially less than or equal to 2000 nm) can be applied in the region of layer 6a. In some preferred exemplary embodiments, the material of the metal mirror layer can be selected depending on 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. aluminum or silver for visible light (e.g. with a wavelength substantially of 400 nm to 700 nm), or gold for infrared light or infrared radiation (e.g. with a wavelength substantially of 850 nm to 2000 nm).

[0160] In accordance with Figure 3 In another exemplary step S310 of the process (e.g., similar to Figure 1 S109 in the figure), the layer structure is exemplarily opened at the back side so as to expose the functional layer 3 on the side opposite to the piezoelectric layer 4; see also Figure 4B (x), wherein, for example, the substrate layer 1 is opened on the back side toward the intermediate layer 2 (for example, by high-speed etching or reactive ion deep etching), and see Figure 4B (xi) wherein, for example, the intermediate layer 2 is open on the back side toward the functional layer 3 .

[0161] In accordance with Figure 3 In another exemplary step S311 of the method (e.g., similar to Figure 1 S110 in Figure 5The fabricated layer structure is provided in a vacuum-packaged MEMS device 200. Here, for example, the layered structure is hermetically sealed from above with a translucent cover element 7 (e.g. a translucent dome element or a glass dome) and from below with a base element 8 under a vacuum atmosphere (e.g. vacuum packaging). In some exemplary embodiments, differently shaped cover elements or 3D-shaped cover elements are also possible (e.g. angular or planar). The material of the cover element is preferably translucent, for example glass or other optically transparent materials (e.g. about 400 nm to 2500 nm), such as borosilicate glass (e.g. SCHOTT's ). BF33).

[0162] Figure 5 Shown according to FIG. 4A to FIG. 4B An exemplary cross-sectional view of a MEMS device 200 manufactured by an exemplary manufacturing sequence of FIG. Therefore, a vacuum-packaged MEMS mirror device 200 (e.g., a MEMS mirror scanner) including the manufactured layered structure can be provided with a piezoelectrically deflectable or controllable mirror 6a, wherein the corresponding layered structure or the MEMS device 200 including the layered structure conveniently has smooth or glossy and / or crystal defect-free sidewalls and rounded corners at the structured areas and grooves of the functional layer, so that the fracture limit of the moving or oscillating part of the functional layer or in particular the spring structure formed in the functional layer can be significantly improved, and the occurrence of premature fracture of the spring structure can be successfully reduced. Compared to the prior art, i.e. when components are manufactured without solidified side walls (i.e. in particular without smooth side walls and / or without rounded corners), wherein fracture may occur in particular at smaller deflection angles or deflection amplitudes, the occurrence of fracture of the deflection structure or spring structure can be conveniently and significantly reduced, and in particular, larger deflection angles or deflection amplitudes can also be achieved, at which larger deflection angles or deflection amplitudes, fracture of the deflection structure or spring structure has already occurred in components manufactured according to the prior art.

[0163] FIG. 6A to FIG. 6B Shown based on Figure 3 , an exemplary cross-sectional view of a layer structure during a manufacturing process according to another exemplary manufacturing sequence. FIG. 6A to FIG. 6B An exemplary sequence is based on Figure 3 Another exemplary embodiment of a process.

[0164] For example, according to Figure 3 The initial step of the method corresponds to Figure 1 Steps S101 to S104 of the method or according to Figure 2A An exemplary manufacturing sequence (i) to (v) of Figure 2A (v) Afterwards, FIG. 6A to FIG. 6B Shown based on Figure 3

[0046] Exemplary manufacturing sequences for some further exemplary embodiments of the methods of.

[0165] Here, too, according to Figure 1 The order of the background examples is reversed, according to Figure 3 Combination FIG. 6A to FIG. 6B In the method, for example, the application of the electrode layer has not yet taken place before the structuring of the functional layer 3, so that a curing step can be carried out after the structuring of the functional layer 3, preferably at a high temperature substantially greater than or equal to 700° C., which electrode layers that have been applied in a conventional manner (for example made of aluminum) cannot withstand.

[0166] In accordance with Figure 3 In the exemplary step S306 of the method (e.g., similar to Figure 1 In step S108), the functional layer 3 is also in the exemplary region 3a according to FIG. 6A to FIG. 6B is structured in the manufacturing sequence of Fig. 6A (v).

[0167] In particular, the mechanically effective structure of the MEMS device is again preferably formed in the functional layer by high-speed etching or deep reactive ion etching (DRIE for short). Structuring the functional layer 3 includes, for example, forming or exposing a mirror support element below the mirror layer 6a, whereby the mirror support element is formed by the functional layer 3 and a retaining web (spring structure), which can be formed by the functional layer 3 and can act as a spring system, and the retaining web can retain the mirror support element so that it can oscillate around one, two or more oscillation and / or torsion axes. In some exemplary embodiments, the spring structure may include a spring, particularly preferably a bending spring and / or a torsion spring, which is preferably designed to retain the mirror support element so that the mirror support element can perform an oscillatory rotational movement (e.g. torsional oscillation) around the corresponding oscillation and / or torsion axis.

[0168] In addition, all the above descriptions of steps S301 to S306 also apply to FIG. 6A to FIG. 6B manufacturing sequence.

[0169] In accordance with Figure 3 In another exemplary step S307 of the method, FIG. 6A to FIG. 6B In the manufacturing sequence, the curing step is exemplarily performed at a high temperature substantially greater than or equal to 700° C. to smooth the side walls of the region 3 a of the functional layer 3 etched deep in step S306 and to round the corners of the region 3 a of the functional layer 3 .

[0170] In some exemplary embodiments, the curing step S307 may include a step of subjecting the surface of the region 3a of the functional layer 3 to a hydrogen annealing step at a temperature substantially greater than or equal to 1000°C and preferably substantially less than or equal to 1250°C (as an alternative or in addition to the above-mentioned sacrificial oxidation).

[0171] As an example, according to Fig. 6A and Figure 6B In the manufacturing sequence of the present invention, after structuring S306 of the functional layer 3 as a curing step according to S307, the surface of the region 3a of the functional layer 3 is subjected to a hydrogen annealing step at a temperature substantially greater than or equal to 900°C, in particular substantially greater than or equal to 1000°C, and preferably substantially less than or equal to 1350°C, in particular substantially less than or equal to 1250°C (see, for example, Fig. 6A (vi)). Hydrogen annealing (see, for example Fig. 6A (vi)).

[0172] After hydrogen annealing in some exemplary embodiments of the curing step S307, the smooth sidewalls of the region 3a of the functional layer 3 with rounded corners are conveniently retained; for example, see Fig. 6A (vi).

[0173] The hydrogen annealing or curing step produces smooth or smooth sidewalls and rounded corners on the surface of the region 3a of the functional layer 3. In particular, any etched scallops and any other surface defects (such as crystal defects, etching, sidewall penetration and atomic defects, etc.) can be reduced or eliminated, so that smooth sidewalls are formed until they are completely transformed into completely smooth and / or crystal defect-free sidewalls. In addition, right-angled structure corners produced during the structuring of the functional layer can be rounded (rounded or rounded structure corners).

[0174] After the corresponding curing step S307, the corresponding layer structure or the MEMS device including the layer structure conveniently has smooth or sleek and / or crystal defect-free sidewalls and fillets at the structured areas and grooves of the functional layer, so that the fracture limit of the moving or oscillating part of the functional layer or in particular the spring structure formed in the functional layer can be significantly improved, and the occurrence of early fracture of the spring structure can be successfully reduced. Compared with the prior art, i.e. when the component is manufactured without cured sidewalls (i.e. in particular without smooth sidewalls and / or without fillets), where fracture can occur in particular at smaller deflection angles or deflection amplitudes, the occurrence of fracture of the deflection structure or spring structure can be conveniently significantly reduced, and in particular, larger deflection angles or deflection amplitudes can also be achieved, at which larger deflection angles or deflection amplitudes, fracture of the deflection structure or spring structure has already occurred in the component manufactured according to the prior art.

[0175] In accordance with Figure 3In an exemplary step S308 of the method, the electrode layer 6 is applied after the curing step S307; see also Fig. 6A (vii) Here, for example, the region 5 b previously opened in the dielectric layer 5 is also filled with the material of the electrode layer, in particular, for example, in order to form a bonding pad.

[0176] In some preferred exemplary embodiments, the electrode layer 6 (top electrode layer) can be deposited over the entire surface, for example made of metal, in particular for example aluminum. In some exemplary embodiments, high temperature stable materials (in particular for example high temperature stable metals) can also be used for the electrode layer. In some exemplary embodiments, the curing step can also be carried out after the electrode layer has been applied and / or structured, and optionally also after the layer structure (which preferably comprises high temperature stable and chemically resistant materials) has been opened at the back; see, for example, the following according to Figures 8 to 10 Exemplary embodiments are described.

[0177] In accordance with Figure 3 In another exemplary step S309 of the method, the electrode layer 6 applied to or above the dielectric layer 5 is structured; see also Figure 6B (viii) Here, for example, in the region 5 b opened in the dielectric layer 5 , a bonding pad 6 b is formed with the material of the electrode layer, which can provide an electrical contact with the upper side of the functional layer 3 .

[0178] In accordance with Figure 3 Another exemplary step S310 of the method (e.g., similar to Figure 1 In S109), the layer structure is exemplarily opened on the rear side so as to expose the functional layer 3 on the side opposite to the piezoelectric layer 4; see also Figure 6B (ix), wherein the substrate layer 1 is exemplarily open on the rear side toward the intermediate layer 2, and Figure 6B (x), wherein the intermediate layer 2 is open, for example, on the rear side toward the functional layer 3 .

[0179] In accordance with Figure 3 In another exemplary step S311 of the method (e.g., similar to Figure 1 6 ), the manufactured layer structure is provided exemplarily in the vacuum packaged MEMS device 300 according to FIG. 6 . Here, for example, the layered structure is covered from above with a translucent cover element 7 (e.g. a translucent dome element or a glass dome) (e.g. see Figure 6B(xi)) is hermetically sealed from below with the base element 8. In some further exemplary embodiments, differently shaped cover elements or 3D shaped cover elements are also possible (e.g., angular or planar). The material of the cover element is preferably translucent, for example glass or other optically transparent material (e.g., about 400 nm to 2500 nm), such as borosilicate glass (e.g., SCHOTT's BF33).

[0180] In addition, all the above descriptions of steps S308 to S311 also apply to FIG. 6A to FIG. 6B manufacturing sequence.

[0181] Figure 7 It shows that according to FIG. 6A to FIG. 6B An exemplary cross-sectional view of a MEMS device 300 manufactured by an exemplary manufacturing sequence of FIG. Therefore, a vacuum-packaged MEMS mirror device 300 (e.g., a MEMS mirror scanner) including the manufactured layered structure can be provided with a piezoelectrically deflectable or steerable mirror 6a, wherein the corresponding layered structure or the MEMS device 300 including the layered structure conveniently provides smooth and / or smooth and / or crystal defect-free sidewalls and rounded corners at the structured areas and grooves of the functional layer, so that the fracture limit of the moving or oscillating part of the functional layer or in particular the spring structure formed in the functional layer can be significantly improved, and the occurrence of premature fracture of the spring structure can be successfully reduced. Compared to the prior art, i.e. in the case of components manufactured without solidified side walls (i.e. in particular without smooth side walls and / or without rounded corners), in which fracture may occur in particular at smaller deflection angles or deflection amplitudes, the occurrence of fracture of the deflection structure or spring structure can be significantly reduced, and in particular, larger deflection angles or deflection amplitudes can also be achieved, at which larger deflection angles or deflection amplitudes, fracture of the deflection structure or spring structure already occurs in components manufactured according to the prior art.

[0182] Figure 8 An exemplary flow chart of a process for fabricating a layered structure of a MEMS device according to some further exemplary embodiments of the present disclosure is shown. FIG. 9A to FIG. 9B Shown based on Figure 8 , an exemplary cross-sectional view of a layered structure during a manufacturing process according to an exemplary manufacturing sequence.

[0183] However, for example, according to Figure 8 The initial steps of the process initially correspond again to Figure 1 Steps S101 to S104 of the process or according to Figure 2A An exemplary manufacturing sequence (i) to (v) of Figure 2A (v) Afterwards, FIG. 9A to FIG. 9BShown based on Figure 8 , an exemplary cross-sectional view of a layer structure during a manufacturing process according to an exemplary manufacturing sequence.

[0184] Reference Figure 8 and Figure 2A (i) to (v), in exemplary step S801, a layer structure (e.g., similar to Figure 1 In step S101 in the example, the layer structure exemplarily includes a substrate layer 1 and a functional layer 3. In the exemplary step S802 (e.g., similar to Figure 1 In another exemplary step S803 (e.g., similar to S102 in the example), the piezoelectric layer 4 is applied to the functional layer 3. Figure 1 In S103 ), as an example, the piezoelectric layer 4 applied on or above the functional layer 3 is structured.

[0185] In another exemplary step S804 (e.g., similar to Figure 1 In step S104), a dielectric layer 5 is applied by way of example. The dielectric layer 5 is applied to exemplary regions of the piezoelectric layer 4 and further to exemplary regions of the functional layer 3, which are open after structuring of the piezoelectric layer 4. In some exemplary embodiments, the applied dielectric layer 5 may be open in selected regions, for example to provide regions 5b intended for subsequent bonding pads. In some exemplary embodiments, the applied dielectric layer 5 may also be open or partially open on the structured regions of the piezoelectric layer 4.

[0186] In addition, by way of example, all the descriptions of steps S301 to S304 above also apply to FIG. 9A to FIG. 9B The manufacturing sequence and Figure 8 Steps S801 to S804.

[0187] In accordance with Figure 1 In another exemplary step S805 of the method, an electrode layer 9 is applied to a dielectric layer 5, which dielectric layer may optionally be opened in advance in the region; see also Fig. 9A (v).

[0188] According to Figure 1 In contrast to the order of the background example of , when applying the electrode layer 9, a high temperature stable conductive material is used in step S805. In some preferred exemplary embodiments (instead of, for example FIG. 2A to FIG. 2C For the aluminum of the electrode layer 6 in the embodiment of the present invention, a high temperature stable material can be used, which can withstand a temperature substantially greater than or equal to 700°C, in some further exemplary embodiments, preferably substantially greater than or equal to 800°C and preferably greater than or equal to 1000°C, and in some further exemplary embodiments, particularly preferably substantially greater than or equal to 1250°C.

[0189] In some particularly preferred exemplary embodiments, for example, a conductive silicon layer can be used as the high temperature stable material of the high temperature stable electrode layer 9 (e.g. deposited by physical vapor deposition PVD, by chemical vapor deposition CVD, by plasma enhanced chemical vapor deposition PECVD, etc.). It is particularly preferred to use doped polysilicon as the (non-metallic) high temperature stable material of the high temperature stable electrode layer 9.

[0190] In some further preferred exemplary embodiments, for example, alternatively or additionally, a high temperature stable metal may be used as the material of the high temperature stable electrode layer 9 (eg, molybdenum, platinum, tungsten, tungsten titanium or WTi, tungsten carbide or WC, etc.).

[0191] Such high-temperature stable material used as material for the high-temperature stable electrode layer 9 makes the layer structure further compatible with a high-temperature stable process sequence at a temperature substantially greater than or equal to 700° C. or substantially greater than or equal to 800° C., wherein in particular the already applied electrode layer 9 can also be subjected to a subsequent curing step (for example, sacrificial oxidation and / or hydrogen annealing according to the above-described exemplary embodiments) at a temperature substantially greater than or equal to 700° C., in particular at a temperature substantially between 700° C. and 1250° C.

[0192] In accordance with Figure 8 In another exemplary step S806 of the method (e.g., similar to Figure 1 S106 in, as an example, the electrode layer 9 applied on or above the dielectric layer 5 is structured; see also Fig. 9A (vi) In the exemplary step S806 of structuring the electrode layer 9 , a desired structure of an overlying electrode (top electrode) for controlling the piezoelectric layer 4 may be formed.

[0193] In accordance with Figure 8 In another exemplary step S807 of the method (e.g., similar to Figure 1 S107 in FIG. 1 ), the dielectric layer 5 is exemplarily opened in the region 5a toward the functional layer 3, and also see Fig. 9A (vii) In particular, these are the regions 5a of the dielectric layer 5 to be opened, in which the underlying functional layer 3 is structured to form mechanically active structures (eg spring structures) of the MEMS device.

[0194] Likewise, in some exemplary embodiments, it is provided that the remaining area of ​​the piezoelectric layer 4 does remain completely encapsulated by the dielectric layer 5 (see, for example, Fig. 9A(vii)), i.e., particularly preferably, for example, the remaining area of ​​the piezoelectric layer 4 is completely or indeed remains completely encapsulated between the functional layer 3 and the dielectric layer 5. Conveniently, the layer structure can still withstand high temperature processes at temperatures substantially greater than or equal to 700° C. (e.g., above about 700° C. to 1250° C.) without damaging the encapsulated area of ​​the piezoelectric layer 4. For example, this enables further curing steps, such as the sacrificial oxidation (e.g., at about 800° C.-1250° C.) and / or hydrogen annealing (e.g., at about 1000° C.-1250° C.) processes further described below, even if materials with poor high temperature stability and / or poor chemical stability are used under encapsulation (e.g., for any bottom electrode and / or for the piezoelectric layer).

[0195] Such encapsulation of the structured region of the piezoelectric layer 4 (e.g. by means of a dielectric layer) makes it possible to protect the structured region of the piezoelectric layer 4 despite high temperatures during the curing step and despite the presence of chemically aggressive media, such as oxygen or hydrogen. This may mean that even piezoelectric materials that are unstable or have poor chemical stability at high temperatures, such as PZT, can be used as piezoelectric material (encapsulated during the curing step). In some exemplary embodiments using high-temperature stable and / or chemically resistant piezoelectric materials, it is not necessary to encapsulate the structured region of the piezoelectric layer 4.

[0196] In addition to or as an alternative to encapsulating the piezoelectric layer 4, for example by means of a dielectric layer or encapsulation regions utilizing a dielectric layer, the high temperature stable electrode layer 9 may also be used to encapsulate structured regions of the piezoelectric layer 4. To this end, in some exemplary embodiments, provision may be made for the remaining regions of the piezoelectric layer 4 to be completely or indeed remain completely encapsulated by the high temperature stable electrode layer 9, i.e. the remaining regions of the piezoelectric layer 4 to be completely or indeed remain completely encapsulated between the functional layer 3 and the high temperature stable electrode layer 9 (optionally with an interposed or partially interposed dielectric layer 5).

[0197] Conveniently, the layer structure can still be subjected to high temperature processes at temperatures substantially greater than or equal to 700°C (for example above about 700°C to 1250°C), whereby in particular any piezoelectric material with poor chemical resistance can be protected by encapsulating aggressive media, such as oxygen (for example in a curing step with sacrificial oxidation) and / or hydrogen (for example in a curing step involving hydrogen annealing).

[0198] For example, this enables further curing steps, such as the sacrificial oxidation (e.g., at about 800°C-1250°C) and / or hydrogen annealing (e.g., at about 1000°C-1250°C) processes described below, even if less high temperature and / or less chemically stable materials are used under packaging (e.g., for any bottom electrode and / or for the piezoelectric layer).

[0199] In accordance with Figure 8In another exemplary step S808 of the method (e.g., similar to Figure 1 In step S108), the functional layer 3 is structured in the region 3a, see also Fig. 9A (viii).

[0200] In particular, the mechanically effective structure of the MEMS device is again preferably formed in the functional layer by high-speed etching or deep reactive ion etching (DRIE for short). Structuring the functional layer 3 includes, for example, forming or exposing a mirror support element, which is formed by the functional layer 3 and a retaining web (spring structure), which is formed by the functional layer 3 and acts as a spring system, and the retaining web can retain the mirror support element so that it can oscillate around one, two or more oscillation and / or torsion axes. In some exemplary embodiments, the spring structure may include a spring, particularly preferably a bending spring and / or a torsion spring, which is preferably designed to retain the mirror support element so that the mirror support element can perform an oscillating rotational movement (e.g. torsional oscillation) around the corresponding oscillation and / or torsion axis.

[0201] In accordance with Figure 8 In another exemplary step S809 of the method (e.g., similar to Figure 3 S307 in FIG. 6A to FIG. 6B In the manufacturing sequence, an exemplary curing step is performed at a high temperature substantially greater than or equal to 700° C., in particular to smooth the side walls of the region 3 a of the functional layer 3 etched deep in step S808 and to round the corners of the region 3 a of the functional layer 3 .

[0202] In some exemplary embodiments, the curing step S809 may include a step of oxidizing the surface of the region 3a of the functional layer 3 at a temperature substantially greater than or equal to 700°C, preferably at a temperature substantially greater than or equal to 800°C (e.g., at about 800°C-1250°C). For example, after the structuring S808 of the functional layer 3, sacrificial oxidation may be performed as a curing step according to S809.

[0203] This oxidation can oxidize surface effects produced on the side walls of the deep etched side walls of region 3a of functional layer 3 during etching (e.g., unevenness such as formed noses, waves, so-called fan-shaped depressions, and any other surface defects such as crystal defects, etching, side wall breakthroughs and atomic defects, etc.).

[0204] After the sacrificial oxidation, the sacrificial oxide layer 11 can preferably be selectively removed, and in particular, any etching fan-shaped depressions and any surface defects (such as crystal defects, etching, sidewall penetration and atomic defects, etc.) can be reduced or eliminated to form a smooth sidewall until it is completely transformed into a completely smooth and / or crystal defect-free sidewall.

[0205] In addition, the right-angled structural corners formed during the structuring of the functional layer can be rounded (rounded or filleted structural corners). In some exemplary embodiments of the curing step S809, after the sacrificial oxide layer 11 is selectively removed, the smooth sidewalls and rounded structural corners of the sidewalls of the region 3a of the functional layer 3 are conveniently retained; for example, see Fig. 9B (ix).

[0206] In some exemplary embodiments, the curing step S809 may again include (alternatively or in addition to the surface oxidation) the following step, namely, subjecting the surface of the region 3a of the functional layer 3 to a hydrogen annealing step, for example at a temperature substantially greater than or equal to 1000° C. (e.g., about 1000° C. to 1250° C.). Thus, for example, after the structuring S808 of the functional layer 3, the surface of the region 3a of the functional layer 3 may be subjected to a hydrogen annealing step at a temperature substantially greater than or equal to 1000° C. (e.g., about 1000° C. to 1250° C.) as a curing step according to S809.

[0207] The hydrogen annealing or curing step produces smooth sidewalls and rounded corners on the surface of the region 3a of the functional layer 3. In particular, any etched scallops and any surface defects (such as crystal defects, etching, sidewall penetration and atomic defects, etc.) can be reduced or eliminated, so that smooth sidewalls are formed until they are completely transformed into completely smooth and / or crystal defect-free sidewalls; see, for example Fig. 9B (ix).

[0208] In some exemplary embodiments of the curing step S809, surface effects or surface defects on the sidewalls of the deep-etched sidewalls of the region 3a of the functional layer 3 (e.g., formed noses, waves, so-called scallops, etc.) can be smoothed by curing, for example, by oxidation or sacrificial oxidation and / or by hydrogen annealing (similar to the method according to Figure 3 S307).

[0209] In particular, any etching fan-shaped depressions and any other surface defects (such as crystal defects, etching, sidewall penetration and atomic defects, etc.) can be reduced or eliminated, so that smooth sidewalls are formed until they are completely transformed into completely smooth and / or crystal defect-free sidewalls. In addition, the right-angled structure corners generated during the structuring of the functional layer can be rounded (rounded or rounded structure corners). Therefore, after the curing step S809, the smooth sidewalls of the region 3a of the functional layer 3 with rounded corners are conveniently retained; for example, see Fig. 9A (ix).

[0210] After the corresponding curing step S809, the corresponding layer structure or the MEMS device including the layer structure conveniently has smooth or sleek and / or crystal defect-free sidewalls and fillets at the structured areas and grooves of the functional layer, so that the fracture limit of the moving or oscillating part of the functional layer or in particular the spring structure formed in the functional layer can be significantly improved, and the occurrence of early fracture of the spring structure can be successfully reduced. Compared with the prior art, i.e. when the component is manufactured without cured sidewalls (i.e. in particular without smooth sidewalls and / or without fillets), wherein fracture can occur in particular at smaller deflection angles or deflection amplitudes, the occurrence of fracture of the deflection structure or spring structure can be significantly reduced, and in particular, larger deflection angles or deflection amplitudes can also be achieved, at which larger deflection angles or deflection amplitudes, fracture of the deflection structure or spring structure has already occurred in the component manufactured according to the prior art.

[0211] Furthermore, it may be advantageous to form a mirror layer on the mirror support element of the functional layer 3 formed in step S806 after the curing step S809, in particular if a conductive silicon-based electrode layer 9 has been applied in step S806.

[0212] In some exemplary embodiments, according to Figure 8 The method may thus comprise, for example, a further step S810 of applying a mirror layer 10 to form a mirror 10a on the mirror support element of the functional layer 3; for example, see also Fig. 9B (x).

[0213] Here, too, simple metals such as aluminum can be used. In some preferred exemplary embodiments, the material of the metal mirror layer can be selected according to the desired application of 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., wavelengths substantially 400nm to 700nm), or gold for infrared light or infrared radiation (e.g., wavelengths substantially 850nm to 2000nm). If a conductive material is used, this can also be used as an example for forming the bonding pad 10b; for example, see also Fig. 9B (x).

[0214] In accordance with Figure 8 In another exemplary step S811 of the method (e.g., similar to Figure 1 S109 in the figure), the layer structure is open on the rear side, in particular to expose the functional layer 3 on the side opposite to the piezoelectric layer 4; see also Fig. 9B (xi) wherein, for example, the substrate layer 1 and the intermediate layer 2 are open on the rear side toward the functional layer 3 .

[0215] In accordance with Figure 8 In another exemplary step S812 of the method (e.g., similar to Figure 1 S110 in Fig.10 The fabricated layer structure is provided in a vacuum-packaged MEMS device 400. Here, for example, the layered structure is hermetically sealed from above with a translucent cover element 7 (e.g. a translucent dome element or a glass dome) and from below with a base element 8 in a vacuum atmosphere (e.g. a vacuum package).

[0216] In some exemplary embodiments, different shapes of cover elements or 3D-shaped cover elements are also possible (e.g., angular or flat). The material of the cover element is preferably translucent, such as glass or other optically transparent materials (e.g., about 400nm to 2500nm), such as borosilicate glass (e.g., SCHOTT's BF33).

[0217] Fig.10 Shown according to FIG. 9A to FIG. 9B An exemplary cross-sectional view of a MEMS device 400 manufactured by an exemplary manufacturing sequence of . Therefore, a vacuum-packaged MEMS mirror device 400 (e.g., a MEMS mirror scanner) including the manufactured layered structure can be provided with, for example, a piezoelectrically deflectable or steerable mirror 10a, wherein the corresponding layered structure or the MEMS device 400 including the layered structure conveniently has smooth or glossy and / or crystal defect-free sidewalls and rounded corners at the structured regions and grooves of the functional layer, so that the fracture limit of the moving or oscillating portion of the functional layer or, in particular, the spring structure formed in the functional layer can be significantly improved, and the occurrence of premature fracture of the spring structure can be successfully reduced. Compared with the prior art method without a curing step, according to some exemplary embodiments with a curing step, the fracture limit of the moving or oscillating portion of the functional layer, or, in particular, the spring structure formed in the functional layer can be at least doubled or even increased by five or ten times. Compared to the prior art, the occurrence of fracture of the deflection structure or spring structure can be significantly reduced, i.e. when the component is manufactured without solidified side walls (i.e. in particular without smooth side walls and / or without rounded corners), and in particular at smaller deflection angles or deflection amplitudes, at which fracture of the deflection structure or spring structure has already occurred in the component manufactured according to the prior art.

[0218] Fig.11 An exemplary flow chart of a process for fabricating a layered structure of a MEMS device according to some further exemplary embodiments of the present disclosure is shown.

[0219] However, for example, according to Fig.11 The initial steps of the method again correspond initially to Figure 1Steps S101 to S103 of the method.

[0220] FIG. 12A to FIG. 12B Shown based on Fig.11 , an exemplary cross-sectional view of a layer structure during a manufacturing process according to an exemplary manufacturing sequence.

[0221] Reference Fig.11 and Fig. 12A (i) to (iii), in exemplary step S1101 (e.g., similar to Figure 1 In step S101 of the embodiment, a layer structure is provided, which layer structure exemplarily includes a substrate layer 1 and a functional layer 3. In exemplary step S1102 (e.g., similar to Figure 1 In another exemplary step S1103 (e.g., similar to S102 in the example), the piezoelectric layer 4 is applied to the functional layer 3. Figure 1 In S103 ), as an example, the piezoelectric layer 4 applied on or above the functional layer 3 is structured.

[0222] In addition, by way of example, all the above descriptions of steps S301 to S303 also apply to FIG. 12A to FIG. 12C The manufacturing sequence and Fig.11 Steps S1101 to S1104.

[0223] In contrast to the exemplary embodiment described above, before the dielectric layer 5 is applied, the Fig.11 According to some exemplary embodiments, the functional layer 3 is directly structured ( Fig.11 Step S1104), and then, for example, a curing step S1105 is performed in a state where the structured region of the piezoelectric layer 4 of the layer structure is opened at the top.

[0224] Therefore, preferably, in some exemplary embodiments, a piezoelectric layer 4 comprising a high temperature stable and / or chemically resistant piezoelectric material may be applied in step S1102. In some preferred exemplary embodiments, the high temperature stable and / or chemically resistant piezoelectric layer 4 may include, for example, aluminum nitride (AlN) and / or aluminum scandium nitride (AlScN).

[0225] In accordance with Fig.11 In another exemplary step S1104 of the method (e.g., similar to Figure 1 In step S108), the functional layer 3 is structured in the region 3a, see also Fig. 12A (iii) In particular, the mechanically active structure of the MEMS device is preferably formed in the functional layer by high-speed etching or deep reactive ion etching (DRIE for short).

[0226] Structuring the functional layer 3 comprises, for example, forming or exposing a mirror support element (beneath the subsequently applied mirror layer 6a, see, for example, Fig.13 ), the reflector support element is formed by, for example, the functional layer 3 and a retaining web (spring structure), the retaining web is formed by, for example, the functional layer 3 and can serve as a retaining spring hole structure, and the retaining web can retain the reflector support element so that it can oscillate around one, two or more oscillation and / or torsion axes. In some exemplary embodiments, the spring structure may include a spring, particularly preferably a bending spring and / or a torsion spring, which is preferably designed to retain the reflector support element so that the reflector support element can perform an oscillatory rotational movement (e.g. torsional oscillation) around the corresponding axis around the corresponding oscillation and / or torsion axis.

[0227] In some exemplary embodiments, for example, reactive ion deep etching for structuring the functional layer 3 may be performed using a photolithography mask.

[0228] In accordance with Fig.11 In another exemplary step S1105 of the method (e.g., similar to Figure 3 S307 in FIG. 12A to FIG. 12C In the manufacturing sequence, an exemplary curing step is performed at a high temperature substantially greater than or equal to 700° C., in particular to smooth the side walls of the region 3 a of the functional layer 3 etched deep in step S1104 and to round the corners of the region 3 a of the functional layer 3 .

[0229] In some exemplary embodiments, the curing step S1105 may include a step of oxidizing the surface of the region 3a of the functional layer 3 at a temperature substantially greater than or equal to 700°C, preferably at a temperature substantially greater than or equal to 800°C (e.g., between about 800°C and 1250°C). For example, after the structuring S1104 of the functional layer 3, sacrificial oxidation may be performed as a curing step according to S1105.

[0230] Such oxidation can oxidize surface effects (e.g., non-uniformities such as formed noses, waves, so-called scallops, and any other surface defects such as crystal defects, etching, sidewall breakthroughs, and atomic defects, etc.) produced on the sidewalls of the deep etched sidewalls of the region 3a of the functional layer 3 during etching. After the sacrificial oxidation, the sacrificial oxide layer can preferably be selectively removed, and in particular, any etching scallops as well as any surface defects (e.g., crystal defects, etching, sidewall penetrations, and atomic defects, etc.) can be reduced or eliminated, so that smooth sidewalls are formed until they are completely transformed into completely smooth and / or crystal defect-free sidewalls. In addition, the right-angled structural corners produced during the structuring of the functional layer can be rounded (rounded or rounded structural corners). In some exemplary embodiments of the curing step S1105, after the sacrificial oxide layer 11 is selectively removed, the smooth sidewalls and rounded structural corners of the sidewalls of the region 3a of the functional layer 3 are thus conveniently retained; for example, see Fig. 12A (iv).

[0231] In some exemplary embodiments, the curing step S1105 may again include (alternatively or in addition to the surface oxidation) the following step, namely, subjecting the surface of the region 3a of the functional layer 3 to a hydrogen annealing step, for example at a temperature substantially greater than or equal to 1000° C. (e.g., about 1000° C. to 1250° C.). For example, after the structuring S1104 of the functional layer 3, as a curing step according to S1105, the surface of the region 3a of the functional layer 3 may thus be subjected to a hydrogen annealing step, for example, at a temperature substantially greater than or equal to 1000° C. (e.g., about 1000° C. to 1250° C.).

[0232] The hydrogen annealing or curing step produces smooth sidewalls and rounded corners on the surface of the region 3a of the functional layer 3. In particular, any etched scallops and any surface defects (such as crystal defects, etching, sidewall penetration and atomic defects, etc.) can be reduced or eliminated, so that smooth sidewalls are formed until they are completely transformed into completely smooth and / or crystal defect-free sidewalls; see, for example Fig. 12A (iv).

[0233] In some exemplary embodiments of the curing step S1105, surface effects or surface defects on the sidewalls of the deep-etched sidewalls of the region 3a of the functional layer 3 (e.g., sidewall breakthroughs and atomic defects, or also formed noses, waves, so-called fan-shaped depressions, etc.) can be smoothed by curing, for example, by oxidation or sacrificial oxidation and / or by hydrogen annealing (similar to the method according to Figure 3 After the curing step S1105, the smooth sidewalls of the region 3a of the functional layer 3 with rounded corners are conveniently retained; for example, see Fig. 12A (iv).

[0234] After the corresponding curing step S1105, the corresponding layer structure or the MEMS device including the layer structure conveniently has smooth or smooth and / or crystal defect-free sidewalls and fillets at the structured areas and grooves of the functional layer, so that the fracture limit of the moving or oscillating part of the functional layer or in particular the spring structure formed in the functional layer can be significantly improved, and the occurrence of premature fracture of the spring structure can be successfully reduced. Compared with the method without a curing step in the prior art, according to some exemplary embodiments with a curing step, the fracture limit of the moving or oscillating part of the functional layer, or in particular the spring structure formed in the functional layer, can be at least doubled or even increased five or ten times. Compared with the prior art, that is, when the component is manufactured without curing the sidewall (that is, in particular without smooth sidewalls and / or without fillets), where fracture can occur in particular at a small deflection angle or deflection amplitude, the occurrence of fracture of the deflection structure or spring structure can be significantly reduced, and in particular, a larger deflection angle or deflection amplitude can also be achieved, at which a fracture of the deflection structure or spring structure has already occurred in the component manufactured according to the prior art.

[0235] In accordance with Fig.11 In another exemplary step S1106 of the method, a dielectric layer 5 is applied by way of example; see also Fig. 12B (v) According to Fig. 12B (v) The dielectric layer 5 is applied by way of example to regions of the piezoelectric layer 4 and, furthermore, by way of example, to regions of the functional layer 3 which are open after the structuring of the piezoelectric layer 4 .

[0236] In some exemplary embodiments, the applied dielectric layer 5 may be open in selected areas (according to Fig.11 Step S1107). For example, according to Fig. 12B (vi) In the region 5b, the dielectric layer 5 is open toward the functional layer 3 to provide a region 5b that can be used for a subsequent bonding pad. In some exemplary embodiments, the applied dielectric layer 5 may also be open or partially open on the structured region of the piezoelectric layer 4.

[0237] In a further exemplary step S1108 of the method, by way of example, an electrode layer 6 is applied to a dielectric layer 5, which dielectric layer is optionally previously opened in regions; see also Fig. 12B (vii) Here, for example, the region 5 b previously opened in the dielectric layer 5 , in particular for the purpose of forming a bonding pad, and the opening region 3 a of the trench of the functional layer 3 are at least partially filled with material of the electrode layer 6 .

[0238] In accordance with Fig.11In another exemplary step S1109 of the method, the electrode layer 6 applied on or above the dielectric layer 5 is structured as an example; see also Fig. 12B (viii) In the region 5b opened in the dielectric layer 5, a bonding pad 6b is formed with the material of the electrode layer, which provides electrical contact with the upper side of the functional layer 3. Furthermore, any material of the electrode layer 6 may be removed from the open region 3a of the groove of the functional layer 3.

[0239] In the exemplary step S1109 of structuring the electrode layer 6, a desired structure of an upper electrode (top electrode) for upper electrical contact of the piezoelectric layer 4 is formed. In addition, in the exemplary step S1109 of structuring the electrode layer 6, for example, in the center of the layer structure, according to Fig. 12B (viii) The reflecting mirror 6 a (mirror layer having a reflecting surface) is formed of the material of the electrode layer 6 .

[0240] In such an example, for example, the electrode layer may comprise a metal, in particular aluminum, so that the surface of the electrode layer 6 already has a reflective surface and is suitable for forming the mirror 6a. In a further example, a non-reflective or non-metallic electrode layer (e.g. doped polysilicon) can be provided, in which case a further layer, for example a metallic mirror layer (e.g. as a thin metal film, for example with a layer thickness substantially greater than or equal to 100 nm and / or substantially less than or equal to 2000 nm) may be applied in the region of the layer 6a.

[0241] In some preferred exemplary embodiments, the material of the metal mirror layer can be selected depending on 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., wavelengths substantially from 400 nm to 700 nm), or gold for infrared light or infrared radiation (e.g., wavelengths substantially from 850 nm to 2000 nm).

[0242] In accordance with Fig.11 In another exemplary step S1110 of the method, the layer structure is exemplarily opened at the rear, in particular in order to expose the functional layer 3 on the side opposite to the piezoelectric layer 4; see also Fig. 12C (ix), wherein the substrate layer 1 is exemplarily open at the rear toward the intermediate layer 2, and see Fig. 12C (x), wherein the intermediate layer 2 is open at the rear, for example, toward the functional layer 3 .

[0243] In accordance with Fig.11 In another exemplary step S1111 of the method, the manufactured layer structure is arranged according to Fig.13Here, for example, the layered structure is hermetically sealed from above with a translucent cover element 7 (e.g., a translucent dome element or a glass dome) and from below with a base element 8 in a vacuum packaged MEMS device 500. In some further exemplary embodiments, differently shaped cover elements or 3D shaped cover elements are also possible (e.g., angular or planar). The material of the cover element is preferably translucent, for example, glass or other optically transparent material (e.g., about 400 nm to 2500 nm), such as borosilicate glass (e.g., SCHOTT's ). BF33).

[0244] In the above exemplary embodiment, in particular, steps S1106 and S1107 may be performed similarly to steps S304 and S305, and for example, corresponding to Figure 3 The description and associated exemplary manufacturing sequence may be applicable. In addition, steps S1108 to S1111 may be performed similarly to steps S308 to S311, and for example, Figure 3 The corresponding description and associated exemplary manufacturing sequence may be applicable.

[0245] Fig.13 Shown according to FIG. 12A to FIG. 12C An exemplary cross-sectional view of a MEMS device 500 manufactured by an exemplary manufacturing sequence of . Therefore, a vacuum-packaged MEMS mirror device 500 (e.g., a MEMS mirror scanner) including the manufactured layered structure can be particularly provided with a piezoelectrically deflectable or controllable mirror 6a, wherein the corresponding layered structure or the MEMS device 500 including the layered structure conveniently has smooth or smooth and / or crystal defect-free sidewalls and rounded corners at the structured areas and grooves of the functional layer, so that the fracture limit of the moving or oscillating part of the functional layer or in particular the spring structure formed in the functional layer can be significantly improved, and the occurrence of premature fracture of the spring structure can be successfully reduced. Compared with the prior art method without a curing step, according to some exemplary embodiments with a curing step, the fracture limit of the moving or oscillating part of the functional layer, or in particular the spring structure formed in the functional layer can be at least doubled or even increased by five or ten times. Compared to the prior art, i.e. when components are manufactured without solidified side walls (i.e. in particular without smooth side walls and / or without rounded corners), wherein fracture may occur in particular at smaller deflection angles or deflection amplitudes, the occurrence of fracture of the deflection structure or spring structure can be significantly reduced, and in particular, larger deflection angles or deflection amplitudes can also be achieved, at which larger deflection angles or deflection amplitudes, fracture of the deflection structure or spring structure has already occurred in components manufactured according to the prior art.

[0246] Some exemplary embodiments have been described above, which, based on the prior art, can provide an improved method for manufacturing a layered structure of a MEMS device, in particular to provide a MEMS device including a layered structure whose mechanically acting components have a higher mechanical fracture limit or a lower fracture sensitivity.

[0247] Particularly conveniently, providing a layered structure according to some exemplary embodiments with the structured region of the piezoelectric layer encapsulated under a high temperature stable layer (e.g. under a dielectric layer) enables the integration of one or more high temperature curing steps (such as hydrogen annealing of the deep etch surface, e.g. at about 1000° C.-1250° C., and / or sacrificial oxidation, e.g. etching back the sacrificial oxide layer at about 800° C.-1250° C.), even if a material with poor high temperature stability and / or poor chemical resistance is used under the encapsulation (e.g. for any bottom electrode and / or for the piezoelectric layer, e.g. PZT). In some further exemplary embodiments, a material with better high temperature stability and / or chemical resistance can also be used for the bottom electrode and / or for the piezoelectric layer, so that such a curing step can also be performed without encapsulation.

[0248] In particular, it was found that the integration of a high temperature curing step according to some exemplary embodiments (e.g., by hydrogen annealing and / or by sacrificial oxidation according to some exemplary embodiments) successfully and conveniently enables the deep etched sidewalls of the structured functional layer to be smoothed so as to remove defects and roughness (e.g., scallops, sidewall breakthroughs, atomic defects, etc.) generated on the surface during the etching process (e.g., DRIE). The surface of the structured functional layer can be smoothed to remove defects and roughness (e.g., scallops, sidewall breakthroughs, atomic defects, etc.) generated during the etching process (e.g., DRIE) and to round off right-angle corners generated during the etching process.

[0249] In particular, it was found that roughness values ​​up to 200 nm and generally exceeding 50 nm generally occur on the deep etched sidewalls of the structured functional layer, which can be significantly smoothed to roughness values ​​below about 50 nm (especially less than or equal to 50 nm) by curing according to the above exemplary embodiments (for example, according to some exemplary embodiments, by hydrogen annealing and / or by sacrificial oxidation), significantly smoothed to roughness values ​​below about 50 nm (especially less than or equal to 50 nm), especially smoothed to roughness values ​​less than or equal to 30 nm, especially less than or equal to 10 nm up to about less than or equal to 2 nm-3 nm. In addition, the 90° corners on the deep etched sidewalls of the structured functional layer can be rounded (the corner radius is limited).

[0250] According to some exemplary embodiments, this conveniently leads to a significant improvement in the stability or fracture resistance of the active elements of the MEMS device and in particular the spring structure formed by the functional layer, and an increase in the fracture limit, thereby avoiding premature fracture of the spring structure or fracture of the spring structure at small deflection angles.

[0251] Compared to prior art methods without a curing step, according to some exemplary embodiments with a curing step, the fracture limit of the moving or oscillating part of the functional layer, or in particular the fracture limit of the spring structure formed in the functional layer, can be at least doubled or even increased fivefold or tenfold. Compared to the prior art, i.e. when components are manufactured without cured side walls (i.e. in particular without smooth side walls and / or without rounded corners), in which fracture can occur in particular at smaller deflection angles or deflection amplitudes, the occurrence of fracture of the deflection structure or spring structure can be significantly reduced, and in particular, larger deflection angles or deflection amplitudes can also be achieved, at which larger deflection angles or deflection amplitudes, fracture of the deflection structure or spring structure already occurred in the components manufactured according to the prior art.

[0252] In particular, conveniently, according to some exemplary embodiments, the sidewalls of the region 3a of the functional layer 3 with rounded corners are conveniently smoothed, so that the layer structure has increased load-bearing capacity and stability or fracture stability. It has been proven that the layers of the layered structure (including the functional layer 3 with conveniently smooth sidewalls and rounded corners) result in the functional layer having an improved fracture limit.

[0253] In particular, for example, the original fracture behavior of silicon can be restored by smoothing / curing the sidewalls or curing the sidewall damage and rounding the corners, i.e., for example, having a high elastic modulus (>160 GPa) and a high hardness (about 10 GPa), so that the fracture limit can be significantly improved compared to the prior art without curing. In particular, it has been demonstrated that the fracture limit can be increased from about 0.5 GPa-1.5 GPa to more than 3 GPa, or even more than 5 GPa.

[0254] In some exemplary embodiments providing vacuum packaged MEMS devices, higher quality factors of at least greater than 1000, or greater than 10,000, or greater than 20,000 (at least 5 times or 10 times greater than operation in room atmosphere (approximately 1 bar)) can be achieved by resonant oscillation operation in a vacuum (e.g., <1 mbar).

[0255] It should also be noted that the higher mechanical fracture limit of the layered structure of the MEMS device according to some exemplary embodiments further advantageously enables a larger deflection amplitude of the active element, such as the scanning amplitude of the oscillating mirror surface, to be increased. Conveniently, according to some exemplary embodiments, the size of the MEMS device can be different or smaller, i.e. have a more compact design, which in turn can result in significant cost savings. Due to the higher fracture limit, higher stress values ​​in the spring can be advantageously avoided, which enables, according to some further exemplary embodiments, conveniently using shortened springs. This may mean, for example, that more space can be conveniently provided for the mirror plate, while the chip size remains the same, so that a larger mirror plate can be manufactured, thereby providing a higher optical resolution.

[0256] Some exemplary embodiments of layered structures with multiple layers have been described above. It should be noted that the embodiments should not be understood as being restrictive in the sense that no other intermediate layers may be present in further exemplary embodiments. On the contrary, in some further exemplary embodiments, further layers and / or intermediate layers may be provided, and / or the described layers may be omitted.

[0257] It should be noted that only some examples or some exemplary 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-described exemplary embodiments and their exemplary embodiment features or the combination of their descriptions, but further includes modifications to the described exemplary embodiments, in particular modifications covered by the features of the examples or by a 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 (S301; S801; S1101) a layered structure including a substrate layer (1) and a functional layer (3); applying (S302; S802; S1102) a piezoelectric layer (4), in particular on the side of the functional layer (3) opposite to the substrate layer (1); Structuring the piezoelectric layer (4) (S303; S803; S1103) to form a structured region of the piezoelectric layer (4); Structuring the functional layer (3) (S306; S805; S1104) to form a structured region of the functional layer (3); as well as The grooves in the structured region of the functional layer (3) are cured (S307; S809; S1105) at a temperature substantially greater than or equal to 700°C.

2. The method according to claim 1, characterized in that The curing (S307; S809; S1105) of the structured region of the functional layer (3) is performed in order to at least partially smooth the side walls of the grooves in the functional layer (3) and / or to round the corners of the grooves in the functional layer (3).

3. The method according to claim 1 or 2, characterized in that: The curing (S307; S809; S1105) of the structured region of the functional layer (3) is performed at a temperature substantially greater than or equal to 800°C.

4. The method according to at least one of the preceding claims, characterized in that The curing (S307; S809; S1105) of the structured region of the functional layer (3) is carried out at a temperature substantially less than or equal to 1400°C, in particular at a temperature substantially less than or equal to 1350°C.

5. The method according to at least one of the preceding claims, characterized in that The curing (S307; S809; S1105) of the structured region of the functional layer (3) comprises hydrogen annealing.

6. The method according to claim 5, characterized in that The hydrogen annealing is performed at a temperature substantially greater than or equal to 900°C and / or substantially less than or equal to 1350°C, in particular at a temperature substantially greater than or equal to 1000°C and / or substantially less than or equal to 1250°C.

7. The method according to at least one of the preceding claims, characterized in that The curing (S307; S809; S1105) of the structured region of the functional layer (3) includes oxidizing the side walls of the trench in the functional layer (3).

8. The method according to claim 7, characterized in that The oxidation of the sidewalls of the trench in the functional layer (3) is performed at a temperature substantially greater than or equal to 700°C, in particular at a temperature substantially greater than or equal to 800°C and / or substantially less than or equal to 1250°C.

9. The method according to claim 7 or 8, characterized in that: The solidification (S307; S809; S1105) of the structured region of the functional layer (3) further comprises removing an oxide layer (11) on the side walls of the trench formed in the functional layer (3), in particular by etching.

10. The method according to at least one of the preceding claims, characterized in that After the curing (S307; S1105) of the structured area of ​​the functional layer (3), an electrode layer (6) is applied (S308; S1108) to form an electrode structure of the structured area of ​​the piezoelectric layer (4) and / or to form a reflector and / or a mirror layer (6a) on one or more structured areas of the functional layer (3).

11. The method according to at least one of claims 1 to 9, characterized in that Prior to the curing (S809) of the structured region of the functional layer (3), a high temperature stable electrode layer (9) is applied (S805) to form an electrode structure for the structured region of the piezoelectric layer (4).

12. The method according to claim 11, characterized in that The material of the high temperature stable electrode layer (9) comprises conductive doped silicon, in particular doped polysilicon.

13. The method according to claim 11 or 12, characterized in that: The material of the high temperature stable electrode layer (9) includes a high temperature stable metal, a high temperature stable metal alloy and / or a high temperature stable metal compound.

14. The method according to claim 13, characterized in that The material of the high temperature stable electrode layer (9) comprises platinum, molybdenum and / or a high temperature stable molybdenum alloy or molybdenum compound, tungsten or a high temperature stable tungsten alloy or tungsten compound, in particular tungsten titanium and / or tungsten carbide.

15. The method according to at least one of claims 11 to 14, characterized in that The high temperature stable electrode layer (9) is applied and / or structured so that the structured region of the piezoelectric layer (4) is encapsulated between the functional layer (3) and the high temperature stable electrode layer (9), optionally with an inserted dielectric layer (5) or a partially inserted dielectric layer (5).

16. The method according to at least one of the preceding claims, characterized in that After curing ( S809 ) of the structured regions of the functional layer ( 3 ), a further layer is applied ( S810 ) to form a mirror and / or a mirror layer ( 10 a ) on the structured region or regions of the functional layer ( 3 ).

17. The method according to at least one of the preceding claims, characterized in that Prior to curing (S307; S809) of the structured regions of the functional layer (3), and in particular prior to application of the electrode layer (6; 9), a dielectric layer (5) is applied (S304; S804) at least onto the structured regions of the piezoelectric layer (4).

18. The method according to claim 17, characterized in that The dielectric layer (5) is applied such that the structured region of the piezoelectric layer (4) is encapsulated between the functional layer (3) and the dielectric layer (5) applied to the structured region of the piezoelectric layer (4).

19. The method according to claim 17 or 18, characterized in that During or before the structuring (S306; S805) of the functional layer (3), regions of the dielectric layer (5) are structured and / or regions of the dielectric layer are opened (S305; S807).

20. The method according to claim 19, characterized in that The dielectric layer (5) is structured and / or opened such that the structured region of the piezoelectric layer (4) remains encapsulated between the functional layer (3) and the dielectric layer (5) applied to the structured region of the piezoelectric layer (4).

21. The method according to at least one of the preceding claims, characterized in that The material of the piezoelectric layer (4) comprises ferroelectric and / or piezoelectric materials, in particular aluminum nitride (AlN), aluminum scandium nitride (AlScN), lead zirconate titanate (PZT) and / or niobium-doped PZT (PZT-Nb).

22. The method according to at least one of claims 1 to 16, characterized in that After curing (S1105) of the structured region of the functional layer (3), applying (S1106) a dielectric layer (5) at least on the structured region of the piezoelectric layer (4), The material of the piezoelectric layer (4) comprises a ferroelectric and / or piezoelectric material that is stable at high temperatures, in particular aluminum nitride (AlN) and / or aluminum scandium nitride (AlScN).

23. The method according to at least one of the preceding claims, characterized in that The structured region of the functional layer (3) comprises one or more movable elements formed in the functional layer (3) and / or a spring structure formed in the functional layer (3), wherein the spring structure in particular holds the one or more movable elements.

24. The method according to claim 23, characterized in that The one or more active elements of the structured region of the functional layer (3) comprise a mirror support element, wherein the mirror (6a; 10a) is arranged on the mirror support element.

25. The method according to claim 24, characterized in that The spring structure of the structured area of ​​the functional layer (3) holds the reflector support element having the reflector (6a; 10a), and the spring structure in the functional layer (3) is designed so that the reflector support element having the reflector (6a; 10a) is held so that it can oscillate around one or two axes, in particular an oscillation and / or torsion axis, particularly preferably for two-dimensional Lissajous scanning movement of the reflector support element having the reflector (6a; 10a).

26. The method according to at least one of the preceding claims, characterized in that The structuring (S306; S805; S1104) of the functional layer (3) includes high-speed etching and / or reactive ion deep etching.

27. A layered structure manufactured by the method according to at least one of the preceding claims, comprising: A substrate layer (1); Structured functional layer (3); and a structured piezoelectric layer (4), the structured piezoelectric layer being located on a side of the functional layer (3) opposite to the substrate layer (1), The trenches of the functional layer (3) in the structured region of the functional layer (3) are solidified, and in particular the trenches have smooth and / or crystal defect-free side walls and / or rounded corners.

28. The layered structure according to claim 27, characterized in that In the structured region of the functional layer (3), the surface roughness of the side walls of the trenches of the functional layer (3) is substantially less than or equal to 50 nm, in particular substantially less than or equal to 30 nm, particularly preferably less than or equal to 10 nm.

29. A MEMS device, in particular a MEMS mirror arrangement (200; 300; 400; 500), comprising a layered structure according to claim 27 or 28.

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