Method for manufacturing a microelectromechanical structure and microelectromechanical structure

Abstract

A method for manufacturing a microelectromechanical structure is proposed, having the following steps: forming a first and a second functional layer having notches, a third functional layer and three insulating layers arranged therebetween, the structured lateral area of the third functional layer defining a movable structure, the insulating layers and the first and second functional layers each having a lateral area arranged below the structured lateral area of the third functional layer and corresponding to the vertical projection of the structured lateral area; etching the insulating layers, completely removing the third insulating layer in the lateral area of the third insulating layer and exposing the movable structure, all notches of the first functional layer arranged in the lateral area of the first functional layer being formed by narrow grooves having a width smaller than twice the vertical distance between the first and third functional layers, the first functional layer being formed such that it has at least one electrically insulating section in the lateral area separated from the remaining part of the first functional layer by the grooves. Furthermore a microelectromechanical structure having a substrate and first, second and third functional layers is proposed.

Description

Technical Field

[0001] This invention relates to a method for manufacturing microelectromechanical structures (MEMS) and a MEMS structure. Background Technology

[0002] Methods for manufacturing micromechanical sensors, such as accelerometers and speed sensors, are known in various forms and variations from the prior art. For example, methods described in DE19537814 A1, DE4241 045 C1, and DE4317274 A1 enable the production of movable silicon structures whose movement is measured by determining capacitance changes. These methods are characterized in that the movable silicon structure is formed in a first step by etching a thick functional layer, which is structured by trenches with a high aspect ratio. In a second step, a sacrificial layer beneath the functional layer is removed, resulting in a structure that can move freely relative to a pad. Furthermore, a thin, buried functional layer made of polysilicon can be disposed beneath the movable structure, which serves, for example, as a suspension for the movable or fixed silicon structure or as an electrode or printed conductor. The movable structure is typically protected by a sealed cover. The cover wafer can be applied to the sensor wafer using different bonding methods, and a cavity is usually provided in the cover.

[0003] Importantly for this manufacturing method is that the thickness of the sacrificial layer is chosen to be significantly greater than the thickness of the buried functional layer, because otherwise the movable structure, in the event of horizontal displacement, would impact the edge of the first buried polysilicon layer. However, a disadvantage of these methods is that even with a small thickness of the buried polysilicon layer, the topographie on the underside of the movable layer is always depicted. That is, the topographie structure of the polysilicon layer influences the etched structure on the underside of the movable structure, thereby creating height differences, unevenness, protrusions, and other defects on the underside (see [link to documentation]). Figure 1 This effect is particularly important for speed sensors. In the case of speed sensors, a moving mass is typically excited to perform horizontal oscillating motion, and the vertical offset caused by the Coriolis force is detected by capacitance changes. Whenever the moving structure sweeps across the edge of the embedded electrode surface, the capacitance between the moving structure and the electrode changes due to the morphology on the underside of the moving structure. This results in an interference signal with a frequency twice that of the oscillation. This interference signal makes the correct analysis and processing of the speed signal quite difficult and should be avoided at all costs.

[0004] A method is also known from DE102011 080978 A1, by which a buried polysilicon layer can be manufactured such that no morphological defects occur in the layer above it during etching, and thus the edges of the buried polysilicon layer are avoided from impact by moving structures. Furthermore, it is advantageous in this method to avoid not only such impacts but also the aforementioned interference signals. However, it is disadvantageous in that this method is more complex and correspondingly more expensive to manufacture. Another disadvantage is that, in this method, cavities are created in the sacrificial layer at the location where the buried polysilicon surface is provided, directly affecting the etching of the sacrificial layer, because etching is greatly accelerated in the region of the cavity. While this can be used to achieve strong localized etching, it simultaneously limits the possibility of controlling etching in areas where no buried polysilicon layer is provided.

[0005] Modern speed sensors typically employ two embedded polysilicon layers beneath the movable functional layer. The first embedded layer is usually used solely for printed conductors. The second embedded polysilicon layer serves as a corresponding electrode surface for the movable structure or as a suspension or potential supply for the movable structure. The second polysilicon layer can also serve as printed conductors and / or as a shielding structure (cover), which shields the electrostatic potential between the movable structure and the printed conductors in the first embedded polysilicon layer, thereby preventing unwanted forces on the movable structure. In this arrangement, all embedded polysilicon surfaces are typically placed at a defined potential to ideally generate a negligible potential difference, in which no unwanted force acts on the movable structure, or to create additional controllable forces on the movable structure through the defined potential difference. Conversely, electrically insulating surfaces without a defined potential, i.e., with a floating potential, are not used because this could generate uncontrolled and variable forces on the movable mass. Furthermore, the following is specifically used: if the first buried polysilicon layer, disposed between the second buried polysilicon layer and the substrate, has a notch in a defined region, then the distance between the second buried polysilicon layer and the substrate is very large. Therefore, a large corresponding electrode surface facing the movable structure can be generated in the second polysilicon layer, the corresponding electrode surface having a correspondingly high capacitance, and despite its large area, it has a small capacitance relative to the substrate due to the large distance. By reducing the parasitic capacitance relative to the effective capacitance, a very sensitive sensor can be constructed.

[0006] The manufacturing method in DE102011 080978 A1 can, in principle, be used independently for two buried polysilicon layers; however, such manufacturing is therefore very expensive and complex. Furthermore, another drawback arises: it is impossible to achieve dual use of this method for any buried polysilicon structure. To generate an electrode surface with low parasitic capacitance in the second buried polysilicon plane, the first buried polysilicon layer must always be present in the edge regions so that the entire electrode surface is not etched during sacrificial layer etching (see...). Figure 4 Now, the edge structures in the first buried polycrystalline layer increase the parasitic capacitance of the electrode surface due to their small distance. Therefore, during manufacturing, the edge regions must be selected to be as narrow as possible; however, this creates the risk that the entire electrode surface may be etched if there are fluctuations in the sacrificial layer etching. Summary of the Invention

[0007] Against this backdrop, the objective of the present invention is to provide a manufacturing method by which a movable structure can be fabricated on a substrate having two or more buried functional layers. Here, the manufacturing process should be as simple as possible and produce as few morphologies as possible on the underside of the movable structure. Other objectives are to keep parasitic capacitances as small as possible and to achieve an arrangement stable relative to fluctuations during sacrificial layer etching.

[0008] The core of this invention lies in avoiding morphological defects on the underside of the movable structure through the interaction of two different measures. On one hand, sufficiently narrow trenches are formed in the first functional layer, which do not create defects on the underside of the movable structure during etching. To enable this special configuration to also be used over large areas under the movable structure without increasing its contribution to parasitic capacitance due to the correspondingly large area of ​​the first functional layer, insulating segments (dummy surfaces) are also provided, which are floatingly attached to the remainder of the microelectromechanical structure.

[0009] To describe the geometric relationships, a primary extension plane of the substrate and a direction perpendicular to it are assumed as a reference frame. The direction parallel to the primary extension plane is also referred to laterally below, and "perpendicular or vertical direction" should always be understood as a direction perpendicular to the substrate. The first, second, and third insulating layers and the first, second, and third functional layers are arranged, in particular, parallel to the substrate and vertically above and below each other, wherein one or more additional auxiliary layers may optionally be arranged between the second insulating layer and the second functional layer or between the third insulating layer and the third functional layer. In the following, the lateral region of the third functional layer from which the movable structure is formed by structuring is called the structured lateral region, and corresponds to the lateral extension of the movable structure formed by structuring and exposure (i.e., etching of the third insulating layer below it). The object of the method according to the invention is to minimize the influence of the morphology of the first functional layer on the lower side of the movable structure located vertically above the first functional layer. The region of the (insulating or functional) layer located vertically below the movable structure (or the structured lateral region of the third functional layer) is called the lateral region of the corresponding layer, and corresponds to the vertical projection of the structured lateral region onto the corresponding layer. The configuration according to the invention of the first functional layer having narrow trenches and at least one virtual segment always involves only the lateral region of the first functional layer, because only this lateral region can influence the lower side of the movable structure located vertically above the first functional layer. The functional layer can be made of, for example, polycrystalline silicon, while silicon oxide can be used as the material for the insulating layer.

[0010] One subject of the present invention is a method for manufacturing a microelectromechanical structure (MEMS), comprising the steps of: forming at least one first insulating layer over a substrate; forming a first functional layer on the first insulating layer, wherein the first functional layer has a slot extending over its entire thickness; forming a second insulating layer on the first functional layer; forming a second functional layer over the second insulating layer, wherein the second functional layer has a slot extending over its entire thickness; forming a third insulating layer over the second functional layer; forming a third functional layer on the third insulating layer, wherein a lateral region of the third functional layer is structured such that it has a slot, such that the structured lateral region defines a movable structure, wherein the first, second, and third insulating layers and the first and second functional layers each have a lateral region, the lateral region being... Arranged below the structured lateral region of the third functional layer and corresponding to the vertical projection of the structured lateral region; etching the first, second, and third insulating layers, wherein the third insulating layer in the lateral region of the third insulating layer is completely removed, thereby exposing the movable structure, wherein the second insulating layer in the lateral region is at least partially removed, and the third insulating layer is at least partially removed from the lateral region; wherein all slots of the first functional layer arranged in the lateral region of the first functional layer are formed by narrow trenches, the width of which is less than twice the vertical distance between the first and third functional layers, wherein the first functional layer is formed such that it has at least one electrically insulating segment in the lateral region, the electrically insulating segment being separated from the remainder of the first functional layer by the trench. The method according to the invention has the following advantages compared to the prior art: suppressing the influence of the morphology of the first functional layer on the underside of the movable structure produced by etching. Furthermore, with the configuration according to the invention, the sensitivity to manufacturing fluctuations during the etching of the sacrificial layer is reduced, and the manufacturing process becomes more robust overall. The following description always refers to a single movable structure; however, it is also possible to manufacture microelectromechanical structures with multiple movable masses by means of the method described, in which the lateral regions of the first functional layer according to the invention are respectively applied to two or more regions located below one of the movable structures.

[0011] By etching, the third insulating layer (sacrificial layer) beneath the structured lateral region of the third functional layer is completely removed, thereby exposing the movable structure in this way and, particularly with respect to at least one lateral direction, supporting it in an oscillatory manner. During this etching process, portions of the second and third insulating layers, as well as any any auxiliary layers present, are also removed. Since the morphology of this first functional layer affects the local etching on the exposed underside of the movable structure, the present invention conceives of configuring the morphology such that this effect is minimized. Because this effect is particularly strongly dependent on the size of the slots in the first functional layer and is more pronounced in the case of larger slots, according to the invention, the slots in the lateral region of the first functional layer are formed only in the form of narrow trenches. Here, the width is chosen to be less than twice the vertical distance between the first and third functional layers, i.e., less than twice the sum of the thicknesses of all layers arranged between the first and third functional layers (the second and third insulating layers, the second functional layer, and optional auxiliary layers). This ratio between the lateral width and the vertical distance is advantageously achieved by selecting such a ratio, preventing the formation of morphological defects on the underside of the movable structure during etching. Alternatively, it is conceivable to design the trenches to be narrower, for example, with a width corresponding to the distance between the first and third functional layers, or even just the thickness of the first functional layer. Since the size of the slot in the first functional layer is greatly limited by this configuration principle, it is necessary to additionally avoid large portions of the first functional layer that do not have a direct function (e.g., in the form of controlled electrostatic coupling with other components of the structure) contributing to increased parasitic capacitance. Instead of removing these portions of the first functional layer, according to the invention, these portions are electrically insulated from the remainder of the first functional layer by narrow trenches, so that the "virtual segment" has a floating potential when the sensor is operating and thus reduces parasitic effects.

[0012] The method according to the invention also allows for several advantageous extensions, which are described below.

[0013] According to a preferred embodiment, the width of the trenches in the lateral region of the first functional layer is greater than half the thickness of the first functional layer. In this way, the formation of cavities can be advantageously avoided during the deposition of the second insulating layer. It is also conceivable that at least one trench in the lateral region of the first functional layer has a width greater than half the thickness of the first functional layer, thereby enabling, for example, targeted avoidance of cavities in particularly critical areas. Similarly, it is conceivable that at least one additional trench in the lateral region of the first functional layer has a width less than half the thickness of the first functional layer.

[0014] According to another preferred embodiment, the second functional layer is formed such that it has at least one first and a second segment, and these two segments are electrically insulated from each other. The first functional layer is formed such that it has first and second electrically insulated segments, which are separated from each other by trenches and from the remainder of the first functional layer. The first segment of the first functional layer is disposed below the first segment of the second functional layer, and the second segment of the first functional layer is disposed below the second segment of the second functional layer. Specifically, the first and second segments of the second functional layer can be arranged adjacent to each other and separated from each other, for example, by slots. In this embodiment, the virtual region of the first functional layer is segmented according to the potential of the structure above it. In this way, it is advantageously possible to avoid the first and second segments of the second functional layer coupling to each other through the virtual segments of the first functional layer and generating parasitic capacitance therebetween.

[0015] According to another preferred embodiment, the first functional layer is formed such that it has a shielding segment in a lateral region, the shielding segment being separated from the remainder of the first functional layer by a trench, wherein the shielding segment is disposed below the slot of the second functional layer and is electrically connected to at least one segment of the second functional layer. In this embodiment, at least one shielding structure is disposed in the first functional layer at a particularly critical edge region between the two segments of the second functional layer, the shielding structure being situated at a defined potential to shield forces on a movable structure caused by stray fields from the virtual surface of the first embedded functional layer. In particular, (viewed from the substrate) the shielding structure in the first functional layer covers the slot of the second functional layer, thereby ensuring shielding towards the substrate, especially in the case of wide slots.

[0016] According to another preferred embodiment, the first functional layer is formed such that it has first and second shielding sections in a lateral region, the first and second shielding sections being disposed in the surrounding environment below the slot of the second functional layer, wherein the first shielding section is electrically connected to a first section of the second functional layer, and the second shielding section is electrically connected to a second section of the second functional layer. In particular, the shield structure thus formed is disposed below the edge of the slot of the second functional layer, thereby advantageously achieving a particularly narrow shield structure facing the substrate with low parasitic capacitance. This particularly relates to the trench-shaped slot of the second functional layer, with two shielding sections symmetrically arranged below the two edges of the trench-shaped slot. This solution is particularly advantageous for narrow openings in the second polysilicon layer.

[0017] According to a particularly preferred embodiment, the slot in the second functional layer is formed by the following sub-steps: A trench is formed in the second functional layer, extending over the entire thickness of the second functional layer, wherein the trench is subsequently filled by forming a first auxiliary layer; an etch channel is formed in the first auxiliary layer, the etch channel partially exposing the second functional layer, wherein a sub-region of the second functional layer is removed by subsequent etching and the etch channel is closed by a third insulating layer before the formation of the third functional layer; wherein the first auxiliary layer is at least partially removed during the etching of the third insulating layer. Specifically, the etching of the third insulating layer is achieved through the etch channel, wherein the filled trench and the third insulating layer function as an etch stop. In this embodiment, a method known in particular from DE102011 080978 A1 is used to form a slot in the second functional layer, such that the slot does not create a defect on the underside of the movable structure during etching. Further details regarding the implementation of the method are provided herein in DE102011 080978 A1.

[0018] According to a preferred embodiment, during etching, sub-regions of the first and second insulating layers are removed such that the remaining sub-regions of the first insulating layer form a base structure for a first insulating segment of the first functional layer, and the remaining sub-regions of the second insulating layer form a base structure for a segment of the second functional layer. Similarly, sub-regions of the first and second insulating layers can also be removed such that base structures for first segments of the first or second functional layer are respectively formed, and similarly, base structures for second segments of both functional layers are formed.

[0019] According to another preferred embodiment, at least one printed wire is formed through a first functional layer, and / or at least one electrode, particularly a probe electrode, is formed through a third functional layer.

[0020] Another subject of the invention is a microelectromechanical structure (MEMS) having a substrate and first, second, and third functional layers, wherein the third functional layer has a structured lateral region forming a movable structure, wherein the first and second functional layers each have a lateral region disposed below the structured lateral region of the third functional layer and corresponding to its vertical projection; wherein all slots of the first functional layer disposed in the lateral region of the first functional layer are formed by narrow trenches, the width of which is less than twice the vertical distance between the first and third functional layers, wherein the first functional layer has at least one electrically insulating segment in the lateral region, the electrically insulating segment being separated from the remainder of the first functional layer by the trench. The structure according to the invention can be manufactured, in particular, by means of embodiments of the method according to the invention, and the advantages and embodiments shown with respect to the method directly transfer to the MEMS according to the invention. Specifically, the second functional layer may have at least one first and a second segment, wherein the two segments are electrically insulated from each other, wherein the first functional layer has first and second electrically insulated segments, the first and second electrically insulated segments being separated from each other by trenches and from the remainder of the first functional layer, wherein the first segment of the first functional layer is disposed below the first segment of the second functional layer and the second segment of the first functional layer is disposed below the second segment of the second functional layer.

[0021] Other advantageous embodiments are derived from the accompanying drawings and related descriptions. Attached Figure Description

[0022] Figure 1 The schematic diagram illustrates microelectromechanical structures known from the prior art.

[0023] Figure 2 The diagram schematically illustrates a microelectromechanical structure with a shroud known from the prior art.

[0024] Figure 3 A microelectromechanical structure is shown, the first functional layer of which has been structured using methods known from the prior art.

[0025] Figure 4 a and 4b illustrate the problems that arise in methods known from the prior art when the first functional layer is structured.

[0026] Figure 5 The illustration schematically shows one embodiment of the microelectromechanical structure according to the present invention.

[0027] Figure 6 This schematically illustrates another embodiment of the microelectromechanical structure according to the present invention.

[0028] Figure 7The illustration schematically shows one embodiment of a microelectromechanical structure with a shielding structure according to the present invention.

[0029] Figure 8 This schematically illustrates another embodiment of a microelectromechanical structure with a shielding structure according to the present invention. Detailed Implementation

[0030] Figure 1 A prior art microelectromechanical structure 4' is shown. This structure is formed by a sequence of layers on a substrate 30, wherein the uppermost layer is formed by a thick functional layer made of silicon, which is configured as a movable silicon structure 1 by creating trenches 2 with a high aspect ratio (see DE 4241 045 C1). The layers immediately below it are removed by etching, thereby exposing the movable structure 1 through the resulting free space 3 (see DE4317274 A1) and allowing it to move freely relative to the pads. Below the movable structure 1, a thin, buried polysilicon layer 5 is disposed on the substrate 30, separated from the substrate 30 by an insulating layer 35'. This functional layer 5 can here be used as a suspension 6 for the movable or fixed silicon structure, or as an electrode 7 below the movable structure 1.

[0031] The notch used to structure the functional layer 5 now has an adverse effect, namely, it creates a localized morphological defect 11 on the underside of the movable structure 1 during etching at that location (here, based on the notch between components 6 and 7 where the defect 11 is generated). When the movable structure 1 sweeps across the edge of the electrode surface 7, the capacitance between the movable structure 1 and the fixed corresponding electrode 7 changes due to the morphology 11 on the underside of the movable structure 11. The associated interference signals distort the true measurement signal and should therefore be avoided at all costs.

[0032] exist Figure 2 In this embodiment, the microelectromechanical structure 4' is protected in a sealed manner by means of a cover 9. The cover wafer 9 can be applied to the sensor wafer by means of various bonding methods, wherein a cavity 10 is typically provided in the cover 9. The first functional layer 5 above the substrate 30 is constructed as printed wires 8 in this embodiment.

[0033] Figure 3This illustrates another possibility for a structured arrangement of layers beneath the movable structure 1. The first buried layer here serves only as a printed conductor 13. A sub-region of the second buried polysilicon layer 14 can be used as a corresponding electrode surface 29 facing the movable structure 1, as a suspension and potential supply for the movable structure 1, as a printed conductor, and also as a shield to shield the potential between the movable structure 1 and the printed conductor 13 in the first buried polysilicon layer. The slot 28 in the first buried layer, arranged below the corresponding electrode 29, has been formed here using the method described in DE102011 080978 A1. At this location, a relatively high parasitic capacitance may potentially occur between the electrode 29 and the substrate 30; however, this is specifically taken advantage of the fact that the distance 15 between the second buried polysilicon layer 14 and the substrate 30 in the sub-region 28 is very large, resulting in a very small parasitic capacitance.

[0034] exist Figure 4 A and 4b show the drawbacks of the method in DE102011 080978 A1: the dual application of the method (i.e., separately for two functional layers) cannot be unlimited. This method produces... Figure 4 The cavity 12 shown in Figure a greatly accelerates etching in these regions. To create an electrode surface 17 with low parasitic capacitance in the second buried polysilicon plane, the first buried polysilicon layer must always be present in the edge region 16, so that not the entire electrode surface 17 is etched during sacrificial layer etching. The edge structure 16 in the first buried polysilicon layer now increases the parasitic capacitance of the electrode surface 17 due to its smaller distance. While this can be avoided by selecting the edge region 16 to be as narrow as possible, it presents the risk that the entire electrode surface 17 may be etched in the presence of fluctuations during sacrificial layer etching, as exemplarily seen in… Figure 4 As shown in b.

[0035] exist Figure 5The diagram depicts one embodiment of the microelectromechanical structure 4 according to the present invention. The layer sequence on the substrate 30 consists of a first insulating layer 31, a first functional layer 41, a second insulating layer 32, a second functional layer 42, an insulating layer 33 (removed here), and a third functional layer 43. The lateral region 25 of the third functional layer 43 is configured as a movable structure 1. To avoid topographic defects 11 on the underside of the movable structure 1 during etching, defined configuration principles are applied in the layers below it to reduce this effect. Here, only those layer regions that can affect the structure on the underside of the movable structure 1 are vertically arranged below the movable structure 1, and whose geometry corresponds to the vertical projection of the structured lateral region 25 onto the corresponding layer. The corresponding regions are referred to as the lateral regions of the associated layers. According to the present invention, the slots 18 in the lateral region of the first functional layer 41 are formed by narrow trenches 18, the width 22 of which is less than twice the distance 15 between the first and third functional layers 41, 43. Furthermore, an electrically insulating segment 19 is provided in the lateral region 15 of the first functional layer 41. This electrically insulating segment is separated from the remainder of the first functional layer 41 by a trench 18, thus forming a "virtual surface" with a floating potential. In the illustrated embodiment, sub-regions of the first and second insulating layers 31, 32 are also removed during etching such that the retained sub-region 23 of the first insulating layer 31 forms a base structure 23 for the first insulating segment 19 of the first functional layer 41, and the retained sub-region 23' of the second insulating layer 32 forms a base structure 23' for the segment 20 of the second functional layer 42.

[0036] exist Figure 6 In the middle, the electrode has two separate segments 20 and 20' located at different potentials. The first functional layer 41 is segmented according to these potentials and is correspondingly divided into two segments 19 and 19'.

[0037] exist Figure 7 In this first functional layer 41, a shielding segment 21 is provided in a lateral region, the shielding segment being separated from the remainder of the first functional layer 41 by a trench 18. The shielding segment 21 is disposed below the slot 26 of the second functional layer 42 and is electrically connected to at least one segment 20 of the second functional layer 42. The shielding segment 21 forms a shield structure that covers the opening 26 and is situated at a defined potential, thereby ensuring shielding towards the substrate 30.

[0038] For the narrow opening in the second functional layer 42, such as in Figure 8As shown, the following shielding sections 21 and 21' are advantageous: these shielding sections are symmetrically arranged on both sides, thus achieving a particularly narrow shield structure with low parasitic capacitance facing the substrate 30. Here, the first shielding section 21 is electrically connected to the first section 20 of the second functional layer 42, and the second shielding section 20' is electrically connected to the second section 20' of the second functional layer 42.

Claims

1. A method for manufacturing microelectromechanical structures (4), the method comprising the following steps: At least one first insulating layer (31) is formed over the substrate (30); A first functional layer (41) is formed on the first insulating layer (31), wherein, The first functional layer (41) is provided with a slot (18) extending over the entire thickness of the first functional layer (41). A second insulating layer (32) is formed on the first functional layer (41); A second functional layer (42) is formed above the second insulating layer (32), wherein the second functional layer (42) is provided with a slot (26) extending over the entire thickness of the second functional layer (42). A third insulating layer (33) is formed above the second functional layer (42); A third functional layer (43) is formed on the third insulating layer (33), wherein the lateral region of the third functional layer (43) is structured such that it has a slot (2) such that the structured lateral region (25) defines a movable structure (1), wherein the first, second and third insulating layers (31, 32, 33) and the first and second functional layers (41, 42) each have a lateral region, the lateral region being arranged below the structured lateral region (25) of the third functional layer (43) and corresponding to the vertical projection of the structured lateral region (25); The first, second, and third insulating layers (31, 32, 33) are etched, wherein the third insulating layer (33) in the lateral region of the third insulating layer (33) is completely removed and thereby exposes the movable structure (1), wherein the second insulating layer (32) in the lateral region is at least partially removed and the third insulating layer (33) is at least partially removed from the lateral region. In this arrangement, all slots (18) in the transverse region of the first functional layer (41) are formed by narrow grooves (18) with a width (22) less than twice the vertical distance (15) between the first and third functional layers (41, 43). The first functional layer (41) is formed such that it has at least one electrically insulating segment in the transverse region, which is separated from the remainder of the first functional layer (41) by the grooves (18).

2. The method according to claim 1, wherein, The width (22) of the groove (18) in the lateral region of the first functional layer (41) is greater than half the thickness of the first functional layer (41).

3. The method according to claim 1 or 2, wherein, The second functional layer (42) is formed such that it has at least one first and second segments (20, 20') and the two segments (20, 20') are electrically insulated from each other, wherein the first functional layer (41) is formed such that it has first and second electrically insulating segments (19, 19') separated from each other by a trench (18) and separated from the remainder of the first functional layer (41), wherein the first segment (19) of the first functional layer (41) is disposed below the first segment (20) of the second functional layer (42) and the second segment (19') of the first functional layer (41) is disposed below the second segment (20') of the second functional layer (42).

4. The method according to claim 1 or 2, wherein, The first functional layer (41) is formed such that it has a shielding segment (21) in the transverse region, the shielding segment being separated from the remainder of the first functional layer (41) by a groove (18), wherein the shielding segment (21) is arranged below the slot (26) of the second functional layer (42) and is electrically connected to at least one segment (20) of the second functional layer (42).

5. The method according to claim 1 or 2, wherein, The first functional layer (41) is formed such that it has first and second shielding sections (21, 21') in the transverse region, the first and second shielding sections being arranged in the surrounding environment below the slot (26) of the second functional layer, wherein the first shielding section (21) is electrically connected to the first section (20) of the second functional layer (42), and the second shielding section (20') is electrically connected to the second section (20') of the second functional layer (42).

6. The method according to claim 1 or 2, wherein, The slot (26) in the second functional layer (42) is formed by the following sub-steps: A trench is formed in the second functional layer (42) and the trench extends over the entire thickness of the second functional layer (42), wherein the trench is subsequently filled by forming a first auxiliary layer; An etch channel is formed in the first auxiliary layer, the etch channel exposing a portion of the second functional layer (42), wherein a sub-region of the second functional layer (42) is removed by subsequent etching and the etch channel is closed by the third insulating layer (33) before the third functional layer (43) is formed; The first auxiliary layer is at least partially removed during the etching of the third insulating layer (33).

7. The method according to claim 1 or 2, wherein, During etching, sub-regions of the first insulating layer (31) and the second insulating layer (32) are removed such that the remaining sub-region (23) of the first insulating layer (31) forms a base structure (23) for the first insulating segment (19) of the first functional layer (41) and the remaining sub-region (23') of the second insulating layer (32) forms a base structure (23') for the segment (20) of the second functional layer (42).

8. The method according to claim 1 or 2, wherein, At least one printed wire is formed through the first functional layer (41), and / or at least one electrode is formed through the third functional layer (43).

9. The method according to claim 8, wherein, The electrode is a detection electrode.

10. A microelectromechanical structure (4), said microelectromechanical structure having a substrate (30) and first, second, and third functional layers (41, 42, 43), wherein, The third functional layer (43) has a structured lateral region (25) that forms a movable structure (1), wherein the first and second functional layers (41, 42) each have a lateral region that is arranged below the structured lateral region (25) of the third functional layer (43) and corresponds to the vertical projection of the structured lateral region (25). In this arrangement, all slots (18) in the transverse region of the first functional layer (41) are formed by narrow grooves (18), the width (22) of which is less than twice the vertical distance (15) between the first and third functional layers (41, 43). The first functional layer (41) has at least one electrically insulating segment in the transverse region, which is separated from the remainder of the first functional layer (41) by the grooves (18).

11. The microelectromechanical structure (4) according to claim 10, wherein, The second functional layer (42) has at least one first and second segments (20, 20') that are electrically insulated from each other, wherein the first functional layer (41) has first and second electrically insulated segments (19, 19') that are separated from each other by a trench (18) and from the remainder of the first functional layer (41), wherein the first segment (19) of the first functional layer (41) is disposed below the first segment (20) of the second functional layer (42) and the second segment (19') of the first functional layer (41) is disposed below the second segment (20') of the second functional layer (42).

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