Micromechanical component and method for manufacturing the same

Abstract

The invention relates to a component (16) for a micromechanical system and a method for producing the component. The component has an upper side and an underside opposite the upper side and comprises: at least one first structural element, which is arranged in a first region of the component (16) and is bounded by at least one first gap (19); and at least one second structural element, which is arranged in a second region (22) of the component (16) that is different from the first region (21) and is bounded by at least one second gap (20). The first region (21) is defined by a first recess (6) in the underside of the component (16), wherein a first thickness (C) of the component (16) in the first region (21) is reduced relative to a second thickness (B) of the component (16) in the second region (22). A second minimum gap width of the at least one second gap (20) is greater than a first minimum gap width of the at least one first gap (19).

Description

Technical Field

[0001] The invention relates to a micromechanical component for a microelectromechanical system (MEMS) and to a method for producing the micromechanical component. Background Art

[0002] MEMS (micro-electromechanical systems), for example, movable spring-mass systems as sensors or actuators, are currently manufactured using silicon technology using various technical methods. This production is usually carried out in batch processes on wafers. When manufacturing MEMS systems that operate on the electrostatic or capacitive principle, surface or near-surface technologies (e.g. SiO 2 Polysilicon layer on a sacrificial layer, SOI technology, cavity SOI technology, SCREAM technology, etc.) These technologies have in common that micromechanical elements made of a silicon layer and having a typical thickness of between 10 μm and 75 μm are structured by etching gaps using anisotropic dry etching.

[0003] For the production of the structure, the aspect ratio (ratio of gap depth to gap width) is an important parameter. A high aspect ratio (HAR) of the gap of the capacitive structure enables a high sensitivity for the sensor and a better force input for the actuator. A large structural height enables a high aspect ratio with respect to the spring on the one hand and thus a lower lateral sensitivity (suppression of undesired movement modes) and on the other hand allows a larger mass and thus lower noise. A large structural height and a HAR are therefore desirable for highly sensitive MEMS.

[0004] However, the technically achievable aspect ratio of the gap using etching cannot be increased arbitrarily. The aspect ratio is limited by the speed at which the etching medium can enter the narrow gap and the speed at which the reaction products can be discharged from the gap. Therefore, the phenomenon of aspect ratio dependent etching ("ARDE" - English: aspect ratio dependent etching) is known, that is, a narrow gap reaches a smaller etching depth in the same time than a wider gap. The reaction and the resulting etching profile are influenced by many parameters, especially also by the gap length. Typically, the aspect ratios provided by basic process suppliers are in the range of 10:1 to 30:1, and the common gap widths achieved using etching technology are in the range of 2 to 3 μm. Further increases in the aspect ratio can only be achieved if the etching process is significantly improved. Summary of the invention

[0005] The object of the present invention is to at least partially circumvent the problems arising from the prior art and to provide a high-performance component with a large aspect ratio and a method for producing such a component quickly and economically. For example, it should be possible to produce narrow gaps with a high aspect ratio by etching and at the same time achieve a high degree of flexibility with respect to the structure height, structure width and gap width for the structure to be produced.

[0006] The object is achieved by a component according to a first aspect and by a method according to a second aspect.

[0007] In a first aspect, a component for a micromechanical system has an upper side and a lower side opposite the upper side, the component comprising: - at least one first structural element, the first structural element is arranged in a first region of the component and is bounded by at least one first gap; - at least one second structural element, the second structural element is arranged in a second region of the component different from the first region and is bounded by at least one second gap; wherein the first region is defined by a first recess in the lower side of the component and a first thickness of the component in the first region is reduced relative to a second thickness of the component in the second region; wherein the at least one first gap extends from the upper side to the lower side in the first region and ends in the first recess and has a first gap depth defined by the first thickness of the component in the first region; wherein the at least one second gap extends from the upper side to the lower side in the second region and ends outside the first recess and has a second gap depth defined by the second thickness of the component in the second region, the second gap depth being greater than the first gap depth of the first gap; and wherein a second minimum gap width of the at least one second gap is greater than the first minimum gap width of the at least one first gap.

[0008] In a second aspect, a method for manufacturing a component for a micromechanical system includes at least the following steps: introducing a first recess into the underside of a blank, whereby the blank has a first thickness extending in the z direction in a first region defined by the first recess, the first thickness being smaller than a second thickness extending in the z direction in a second region different from the first region, etching at least one first gap in the first region to produce at least one first structural element defined by the at least one first gap; and etching at least one second gap in the second region to produce at least one second structural element defined by the at least one second gap; wherein the etching is respectively performed along the z direction and is carried out such that the at least one first gap has a first gap depth defined by the first thickness, the first gap depth is smaller than a second gap depth of the at least one second gap defined by the second thickness in the second region, and a first minimum gap width of the at least one first gap is smaller than a second minimum gap width of the at least one second gap.

[0009] The proposed component for a micromechanical system has an upper side and a lower side opposite to the upper side. At least one first structural element is arranged in a first region of the component, the first structural element being bounded by at least one first gap. At least one second structural element is arranged in a second region of the component different from the first region, the second structural element being bounded by at least one second gap. Here, the first region is defined by a first recess in the lower side of the component. The first thickness of the component in the first region is reduced due to the recess relative to the second thickness of the component in the second region. The at least one first gap extends from the upper side to the lower side in the first region and ends in the first recess. The gap depth of the first gap has a gap depth defined thereby by the first thickness of the component in the first region. Similarly, the at least one second gap extends from the upper side to the lower side in the second region and ends outside the first recess. The second gap depth of the second gap is defined by the second thickness of the component in the second region and is thereby greater than the first gap depth. The second minimum gap width of the at least one second gap is here greater than the first minimum gap width of the at least one first gap.

[0010] The coordinate system that can be assigned to the component can be designed such that the first and second thicknesses extend in the z direction and the transverse dimension of the component as well as the gap width and the structural width of the first and second structures extend in the x and / or y direction.

[0011] By means of such a component, for example, a first electrode can be provided in the first region by means of a first structural element, the sensitivity and performance of which is determined according to the capacitor principle primarily by the area of ​​the structural elements which can form electrode elements and their distance from one another. In the initial state, the distance is given by the gap width. A change in the gap width is achieved by means of an oscillating arrangement, which results in a detectable change in the capacitance.

[0012] In the second region, a second gap can be provided in order to decouple the vibrating sections of the component from one another. In the second region, a second structural element, which is designed as a spring, is provided, for example, which enables vibration.

[0013] If a high sensitivity is desired for the electrode in the first region, the gap etched in this region should be kept as narrow as possible, while at the same time the area of ​​the electrode element or first structural element resulting from the product of structure thickness and structure length (corresponding, for example, to the gap length) should be maximized. That is, for a fixed gap length, a high aspect ratio (ratio of structure thickness to gap width) is desired for the electrode element in the first region, for example.

[0014] In the second region, a larger gap size may also be desired in order to achieve a desired function of the spring element or to enable a deflection of a certain magnitude.

[0015] In combination with different desired gap widths, the aforementioned aspect ratio dependent etching (ARDE) effects can become problematic, especially when the width is further reduced to increase capacitance sensitivity. This problem is circumvented by the proposed structure, as explained below.

[0016] In the proposed component, the thickness of the structure in the first region is reduced by the recess, starting from the back side. This appears disadvantageous at first glance, since the capacitive area of ​​the electrode and thus also the sensitivity decreases with the thickness of the structure. However, it has also been shown that the reduction in capacitive sensitivity with decreasing structure thickness affects the sensitivity only linearly, while the increase in capacitive sensitivity due to the reduction in gap width varies quadratically. This means that a reduction in structure thickness can be compensated or overcompensated by a reduction in gap width, so that the sensitivity of the structure is increased despite a smaller structure thickness.

[0017] The inventors therefore proposed such a construction scheme for thickness variation and gap width and a corresponding micromechanical structuring scheme, in which the ARDE effect is purposefully utilized in order to reduce the structural thickness of the region of the capacitive detection element and thereby achieve a minimum gap spacing and increase the capacitive sensitivity, wherein further wider gaps should also be introduced into the same component, such as in the second region in the proposed component.

[0018] The at least one first gap having a smaller gap width than the at least one second gap also has a smaller gap depth than the at least one second gap, thereby reducing the time required for etching the at least one first gap. Unlike a structure in which gaps of different depths are provided in a blank having a constant thickness, it can be achieved here that the etching process for narrower and wider gaps can be performed or ended at the same time or approximately at the same time.

[0019] In the proposed component, a first maximum aspect ratio of the at least one first gap is defined by a first gap depth and a first minimum gap width, and correspondingly a second maximum aspect ratio of the second gap is defined by a second gap depth and a second minimum gap width. In a possible embodiment of the component, the first maximum aspect ratio is equal to or substantially equal to the second maximum aspect ratio. This makes it possible for the manufacturing method to have the same or substantially the same etching time for the at least one first gap and the at least one second gap.

[0020] Here, substantially equal may mean, for example, that the deviation is not greater than 10%, preferably not greater than 5%.

[0021] In a possible embodiment, more than two regions of different thickness may be present in which gaps are introduced, for example three or four regions of different thickness with gaps. These regions may be present in addition to possibly thicker fixing or frame regions that are mostly free of gaps. In this case, the narrowest minimum gap width may be present in the region with the smallest thickness, for example for the gaps located there, the second narrowest minimum gap width may be present in the region with the second smallest thickness, and so on.

[0022] The at least one first structural element can be delimited by the at least one first gap at least on two opposite sides extending at least partially parallel to each other. Alternatively or additionally, the at least one second structural element can be delimited by the at least one second gap at least on two opposite sides extending at least partially parallel to each other. In these embodiments, the at least one first structural element configured in this way or the at least one second structural element configured in this way is designed at least partially as a straight or curved plate.

[0023] Some of the first and second gaps can, for example, extend in the x-direction and be interconnected by further shorter first gaps extending in the y-direction. Two adjacent first or second gaps extending in the x-direction are interconnected, for example, by means of first or second gaps introduced at the gap ends and extending in the y-direction and configured as transverse gaps. For example, adjacent first or second gaps extending in the x-direction are interconnected at alternating gap ends in order to achieve a serpentine structure.

[0024] The proposed component can include a frame and a mass arrangement system that can vibrate relative to the frame. The at least one second structural element can then include an elastic spring that connects the frame and the mass arrangement system to one another, so that the frame and the mass arrangement system can vibrate relative to one another when the spring is deformed. However, the frame and the mass arrangement system can also be completely separated from one another and each connected, for example, to a base body. In this case, the frame is, for example, fixedly connected to the base body, while the mass is connected to the base body by means of so-called anchors.

[0025] Due to the different types of oscillability, the frame and the mass arrangement can be moved relative to one another, for example, by an acceleration of the components.

[0026] The proposed component may comprise one or more anchoring structures which may be arranged fixedly or can be arranged fixedly relative to the frame. For example, the anchoring structure or each of the anchoring structures may be fixed to a substrate, to which the frame is usually also connected or can be fixed, so that the frame and the anchoring structures are fixed relative to each other. To this end, the anchoring structures at least partially have the same thickness as the frame and extend into the first and / or second region in which the electrodes are desired to be present.

[0027] At this time, some electrode elements of the structural elements configured as electrodes can be fixed on the anchoring structure, while other electrode elements or the remaining electrode elements of the structural elements configured as electrodes that should be movable relative to the electrode elements connected to the anchoring structure are connected to the mass arrangement system. In this way, the electrode elements fixed in different ways can vibrate relative to each other, so that the gap spacing between them changes. This can be achieved for the structural elements in the first area in that the at least one first gap extends between the mass arrangement system and the frame or between the mass arrangement system and the anchoring structure. The section of the component located between the mass arrangement system and the frame or the anchoring structure can be separated into two areas that can vibrate relative to each other by the gap. The at least one first structural element defined by the at least one first gap can now include a plurality of first electrode elements, of which at least one electrode element is connected to the frame or the anchoring structure and at least one other electrode element is connected to the mass arrangement system. These differently fixed electrode elements of the first electrode can be engaged with each other and can be movable relative to each other. When the frame and the mass arrangement system move relative to each other, the above-mentioned change of the distance between the structural elements of the first electrodes can be achieved by this arrangement of the electrodes or their electrode elements.

[0028] If an electrode is also or alternatively desired to be present in the second region, for example, further anchoring structures may be present or an anchoring structure may extend into the first and second regions. The second gap then extends in the second region between the anchoring structure and the mass arrangement in a manner similar to the embodiment described above in conjunction with the first gap and separates the differently fixed, mutually engaged electrode elements of the second electrode from one another.

[0029] Alternatively or in addition to the spring, the at least one second structural element can include a second electrode. Furthermore, alternatively or in addition to the spring and / or the second electrode, the at least one second structural element can include a damping element, which can be designed like a second electrode element and, for example, has a larger gap distance than a possible second electrode.

[0030] The minimum structural width of the at least one first structural element may be smaller than the minimum structural width of the at least one second structural element.

[0031] The minimum gap width of the at least one first gap between the structural elements can be, for example, at least 0.1 μm, preferably at least 0.3 μm, and / or at most 3 μm, preferably at most 1.5 μm. Alternatively or additionally, the minimum gap width of the at least one second gap between the structural elements can be, for example, at least 0.5 μm and / or at most 4 μm.

[0032] The first thickness can be, for example, at least 5 μm. Furthermore, the first thickness can be, for example, at most 100 μm, preferably at most 60 μm. Alternatively or additionally, the first thickness can be at least 15%, preferably at least 25%, of the second thickness, but at the same time, for example, at least 5 μm. The first thickness can also be at most 90%, preferably at most 85% of the second thickness. That is, the second thickness can be 100 μm in this exemplary embodiment, while the first thickness can be between 25 μm and 80 μm.

[0033] The first maximum aspect ratio of the at least one first gap and / or the maximum aspect ratio of the at least one second gap can each be, for example, 10:1 or more, preferably 20:1 or more, particularly preferably 25:1 or more.

[0034] The height of the individual structural elements extends in the z-direction and is mostly derived from the thickness of the component in the region in which the respective structural element is located. The height of one or more of the at least one structural element and / or the at least one second structural element can be reduced from the top and / or from the bottom relative to the thickness of the respective region in which the structural element is located, so that the height of the first structural element with a reduced height does not correspond to the first height or thickness, and / or the height of the second structural element with a reduced height does not correspond to the second height or thickness. In this way, for example, the sensitivity of the electrodes in the first and second regions or the flexibility of the springs can be influenced.

[0035] The proposed component may be produced, for example, from silicon, for example single-crystalline silicon.

[0036] The transverse dimension of the component extending perpendicularly to the thickness of the component can be, for example, between 0.5 mm and 15 mm. The transverse dimension of the first recess can be, for example, between 100 μm and 2000 μm. The transverse dimension of the structural element (spring, plate, damper, mass) can be, for example, between 1 μm and 2000 μm.

[0037] In addition to the first recess, a second recess may also be present in the component on the back side of the component. The second region may be defined by the second recess, whereby the second thickness present in the region of the second recess is smaller than the third thickness of a third region different from the first and second regions. The third region is preferably encompassed by the frame and / or the anchoring structure or the anchoring structures. That is, the frame and / or the anchoring structure may have regions which have the third thickness and thus have the greatest thickness compared to the first and second regions. These regions are suitable, for example, for fixing the component to the above-mentioned substrate.

[0038] The micromechanical system or MEMS involved in the present application comprises the proposed component and a base body for fixing the micromechanical component.

[0039] In such a micromechanical system, a component can be fixed on a substrate configured as a bottom substrate, and in order to fix the micromechanical component, the frame of the component and / or the anchoring structure or each of the anchoring structures is connected to the bottom substrate on the bottom side. If there is a second recess, for example, the third region, that is, all sections of the component with the third thickness are connected to the bottom substrate. If the second recess is not provided, for example, the sections constituting the frame and / or anchoring structure of the second region can be connected to the bottom substrate. In this case, it is advantageous that the bottom substrate has a cavity in order to ensure the mobility of the active structure of the component, such as the mass arrangement system or the electrode, and to prevent these structures from contacting the bottom substrate.

[0040] Furthermore, the component is also covered on the top side by a base body designed as a top base body. The top base body usually has a cavity to allow the movable structures of the component, such as the mass arrangement or the electrodes, to be movable and to prevent these structures from coming into contact with the top base body. This is usually necessary because the top side of the component is usually not provided with a recess having this effect.

[0041] In the system, the base body can be made of silicon, preferably single-crystal silicon and / or a glass material or a ceramic material, for example. If the base body is made of a glass material or a ceramic material, it can be adapted to silicon in terms of thermal properties, for example to avoid thermally generated stresses in the component.

[0042] The present application also relates to a method for producing a micromechanical component, which is particularly suitable for producing the micromechanical component described above.

[0043] The method comprises certain steps which do not necessarily have to be carried out in the order described but can, under certain circumstances, also be carried out in the reverse order or simultaneously.

[0044] In one step of the method, a first recess is introduced into the underside of the blank so that the blank has a first thickness extending in the z direction in a first region defined by the first recess, which is smaller than a second thickness extending in the z direction in a second region different from the first region.

[0045] A first gap is etched in the first region in order to form at least one structural element bounded by the at least one first gap. A second gap is etched in the second region in order to form at least one second structural element bounded by the at least one second gap. The etching of the at least one first gap and the at least one second gap can in particular be carried out simultaneously. The etching is respectively carried out in the z-direction so that the at least one first gap has a first gap depth defined by the first thickness, which is smaller than the second gap depth of the at least one second gap defined by the second thickness in the second region. Furthermore, the first minimum gap width of the at least one first gap perpendicular to the z-direction is smaller than the second minimum gap width of the at least one second gap.

[0046] The at least one first gap having a smaller gap width than the at least one second gap also has a smaller gap depth than the at least one second gap, thereby achieving a reduction in the time required for etching the at least one first gap.

[0047] The at least one first gap and the at least one second gap may be etched simultaneously.

[0048] Unlike structures in which gaps of different widths and depths are provided in a blank having a constant thickness, it is possible here to end the etching process for narrower and wider gaps at the same time or approximately at the same time. The reason for this is the aspect ratio-dependent etching, whereby the etching process for narrower gaps proceeds more slowly than for wider gaps.

[0049] In the method presented here, as described above, the etching of the at least one first gap and the at least one second gap is preferably carried out simultaneously. It may be desirable here that the corresponding etching processes start at the same time and end at the same time or approximately at the same time. For this purpose, the at least one first gap and the at least one second gap are predefined by several masks (without additional adjustment tolerances) and etched in a single step. The manufacturing time can be optimized by this single-stage etching process. In the method according to the prior art, the problem arises that, compared with the narrower gap, the wider gap will penetrate to the lower side earlier, which can cause damage to the gap or damage to the material located thereunder. Thus, the embodiment shown here avoids the occurrence of such damage and in particular makes it possible to implement a single-stage etching process even for a variable gap width.

[0050] The at least one first gap and the at least one second gap can be etched from the upper side facing away from the lower side along the z direction toward the lower side. That is, the gaps are etched from the usually smooth upper side toward the lower side having the first recess, so that the first gap ends inside the first recess.

[0051] In one step of the method, a mask, preferably a resist mask and / or a hard mask, can be applied to the upper side of the blank. The mask can be used to predefine geometrical dimensions in a plane perpendicular to the z-direction for the at least one first gap and the at least one second gap. This means, for example, that the first and second gap widths and the first and second structure widths in the x-direction and the y-direction can be predetermined.

[0052] For example, when the blank in which the gap is etched is made of silicon or single-crystal silicon or contains silicon or single-crystal silicon, the etching of the gap may be performed in a dry etching process.

[0053] In the proposed method, a step for introducing a second recess can be provided, which step is performed before the step for introducing the first recess. The second recess is preferably introduced into the underside of the blank by etching, just like the first recess. In some embodiments, the first recess is etched into the underside and then etched inside the second recess in order to further reduce the thickness there, so that the recesses are nested in one another and the first area defined by the first recess is surrounded by the second area that can be defined by the second recess. In addition, a third area can be defined outside the second recess, which has the greatest thickness among the three areas.

[0054] In the method described, in a step after the introduction of the first recess or in a step after the introduction of the first recess and the second recess, a protective layer, for example a protective layer in the form of an oxide layer, can be applied at least partially to the underside of the blank. That is, in this case, the protective layer covers, for example, the first and possibly the second recess. For example, the protective layer can in particular coat or cover the region in which the first and / or second gap ends.

[0055] In some possible steps of the method, the height of one or more of the first structural elements and / or the second structural elements, i.e. one or more of the first and / or the second electrode elements and / or one or more of the springs, can be lowered starting from the top and / or starting from the bottom. This can be done, for example, during the etching process using a mask or, in some cases, using a multi-stage, for example a two-stage, mask with a plurality of mask layers. The two-stage mask can, for example, include a hard mask layer and a resist mask layer.

[0056] The reduction in height of the electrode element or elements starting from the underside can be carried out simultaneously with the introduction of the first cavity by means of a mask arranged on the underside of the blank or component.

[0057] A two-stage mask can be used to achieve a reduction in the height of one or more of the electrode elements from the top side. The two-stage mask can include a hard mask layer and a resist mask layer, for example, which is arranged on the hard mask layer. In a first step or sub-step, the gap predetermined by the upper mask layer, that is, usually the resist mask layer, can be completely etched out, or the gap can only be pre-etched, that is, for example, pre-etched to a predetermined depth. At this time, the upper mask layer can be removed, leaving the lower mask layer, which exposes additional areas on the upper side of the component compared to the upper mask layer. At this time, if the gap is not completely etched out in the first sub-step, the gap can be etched in another step or sub-step, and the additionally exposed area can be etched by a determined amount, thereby achieving the desired reduction in the height of the structural element from the top side.

[0058] The proposed method may include a step in which the blank is connected to the base. For example, the blank can be arranged on the bottom base and fixed to it. For example, it can be provided that, if a protective layer is provided, the blank with the first recess and the possible second recess is fixed to the bottom base after the protective layer is applied to the bottom side of the blank and before the first and second gaps are introduced. In this way, the blank is kept stable by the bottom base during etching. At this time, it is also possible that the blank with the first and second recesses still has a thickness greater than the first, second and possible third thickness that is ultimately desired to be achieved, so as to make it more stable. In this case, the thicker blank can be easily handled and fixed to the bottom base. Then, after the blank is fixed to the bottom base, the thickness can be reduced from the upper side, so that the desired thickness is finally established in the first, second and possible third regions. The gap can be introduced thereafter. This is particularly advantageous when a particularly small thickness is desired, for example a first thickness of 5 μm or less than 5 μm.

[0059] The blank or the component with the first and second gaps arranged on the bottom substrate can then be covered by the top substrate. The blank can be connected to the bottom substrate and / or the top substrate by etching the contact area, preferably the frame and / or the anchoring structure. This can be achieved, for example, by wafer bonding.

[0060] An insulating layer is provided at least in one of the contact regions of the micromechanical component and the bottom and / or top substrate. Alternatively or additionally, a cavity can be introduced into the first and / or second substrate on the side of the bottom and / or top substrate facing the micromechanical component outside the contact region before fixing. It can be achieved that, for example, the second region does not have undesirable contact with the substrate and remains free to move. In particular, when there is no second recess on the lower side of the component connected to the bottom substrate, this is advantageous for the substrate configured as the bottom substrate. In addition, for the substrate configured as the top substrate, the cavity may be advantageous, thereby avoiding that the upper side of the component contacts the top substrate at an undesirable position and is thus hindered in vibration.

[0061] In the method presented here, it should be noted that the first and second recesses can be nested concentrically in one another, for example. The first and / or second recess can also be arranged centrally on the bottom side, which is designed to be rectangular, for example. The first and second gaps should now end in the area defined by the first or, if appropriate, also by the second recess, as described above. That is, the first and second gaps should be etched on the top side at the corresponding positions.

[0062] An additional advantage of the method may be the permissible tolerances, which can be obtained in the positioning of the recess relative to the component and / or in the tolerance of the position of the mask prescribing the gap relative to the recess. Thus, the area defined by the first recess can be, for example, 10 μm to 200 μm larger in the x-direction and / or y-direction than the area of ​​the mask prescribing the first gap. In this way, the mask does not have to be centrally positioned above the first recess with nm-level accuracy in order to achieve the desired function. As a result, an additional simplification of the manufacturing process can be achieved, which helps to reduce costs or automate this manufacturing process. The area of ​​the mask prescribing the at least one second gap is usually selected here so that the at least one second gap is arranged at a sufficient distance from the first gap to ensure that the at least one second gap is introduced in the second area. By moving the position of the mask relative to the recess, although the position of the step between the first area and the second area or the second area and the third area can be changed, this position change is permissible within the range of adjustment accuracy that can be achieved by conventional photolithography.

[0063] It is emphasized that features which are described solely in conjunction with a component may also be claimed for a specified method and vice versa. BRIEF DESCRIPTION OF THE DRAWINGS

[0064] An exemplary embodiment of the present invention is shown in the accompanying drawings.

[0065] Figure 1 A graph showing normalized capacitance and normalized capacitance sensitivity of electrodes arranged over the width of an electrode gap;

[0066] Figure 2 perspective and cross-sectional views showing the proposed components;

[0067] Figure 3 ac show different implementation forms of the proposed component;

[0068] Figure 4 ac show different embodiments of the proposed additionally front-processed component;

[0069] Figure 5 The component with the bottom base body is shown in an embodiment with a protective layer;

[0070] Figure 6 The component with a bottom base body and a top base body is shown in an embodiment with a protective layer;

[0071] Figure 7 The component with the bottom base body and the top base body is shown in an embodiment without a protective layer;

[0072] Figure 8A component with a bottom base body and a top base body is shown in an embodiment with a cavity; and

[0073] Fig. 9 Another view of the component is shown with a bottom base and a top base. DETAILED DESCRIPTION

[0074] Figure 1 A layout is shown in which the normalized capacitance (C normalized, shown by dotted lines) and the normalized capacitance sensitivity dC / dx, i.e. the change in capacitance when the gap width x changes (dC / dx normalized, dotted lines) are marked on the electrode gap width x (the electrode gap is represented by μm). According to the principle of plate capacitors, the capacitance C is obtained from the quotient of the electrode area A and its spacing, i.e. the electrode gap width x: C∝A / x. That is, when the electrode area is constant, the capacitance is inversely proportional to the electrode gap width x. In the figure, for electrode gaps between 0.5μm and 4μm, the capacitance C is normalized to 1 and marked, that is, the inverse relationship is offset (by multiplying by x). When the area A increases or decreases, the normalized capacitance changes proportionally to the area according to C∝A / x.

[0075] The capacitance sensitivity dC / dx is therefore proportional to A / (x^2). For electrode gaps of 0.5μm to 4μm, this value is also normalized (by multiplying by x) and accordingly shows an inverse relationship with the electrode gap. That is, for small gap spacings, the capacitance sensitivity dC / dx increases significantly faster than the capacitance C itself. Area A only affects the capacitance and the capacitance sensitivity linearly. Improving the relationship between capacitance sensitivity and basic capacitance is very beneficial primarily for realizing energy-saving systems. Reducing the basic capacitance achieves reduced current consumption for subsequent capacitance-to-voltage conversion circuits. The ratio of capacitance sensitivity to basic capacitance is significantly improved in areas of small spacing, such as Figure 1 The influence of the electrode spacing x on the capacitive sensitivity can accordingly be significantly stronger than the influence of the electrode area A.

[0076] Figure 2 A micromechanical system (MEMS) is shown in a perspective view and in a sectional view along the section line AA marked in the perspective view.

[0077] In this system, a component 16 is arranged on a base body 15 , the upper side of which can be seen in this perspective view, into which a plurality of recesses 19 , 20 are introduced, which extend from the upper side to an opposite lower side.

[0078] The component 16 and the base substrate 15 on which the component is arranged are made of single-crystalline silicon.

[0079] The transverse dimension of the component in the x-direction and the z-direction perpendicular to the thickness extending in the z-direction is between 0.5 mm and 15 mm.

[0080] The component 16 comprises a plurality of first structural elements 3 constituting electrodes 3, which are arranged in a first region 21 of the component 16 and are delimited by at least one first gap 19. In addition, the component comprises second structural elements 2, 7, some of which constitute electrodes or dampers 7 and others constitute springs 2, and are arranged in a second region 22 of the component different from the first region 21. The second structural elements 2, 7 are delimited by second gaps 20.

[0081] As can be seen in the sectional view AA, the first region 21 is defined by the first recess 6 introduced into the underside of the component. In the first region 21, the component has a first thickness C. The first thickness C of the component in the first region 21 is reduced relative to the second depth B of the component in the second region 22. The first gap 19 extends from the upper side to the lower side in the first region 21 and ends in the first recess 6. The first gap depth of the first gap 19 and also the height of the first structural element 3 located in this region are thus defined by the first thickness C. The first gap 19 comprises first gaps of different widths in the example shown: a narrower first gap 19a and a wider first gap 19b are provided in the first region 21. The lateral dimensions of the first recess 6 in the x-direction and in the y-direction are between 100 μm and 2000 μm. The first thickness C in the z-direction is between 5 μm and 60 μm. The first thickness C reduced relative to the second thickness due to the first recess 6 is here between 25% and 80% of the first thickness.

[0082] The second gap 20 extends from the upper side to the lower side in the second region 22 and ends outside the second recess 6. That is, the gap depth of the second gap and the height of the second structural elements 2, 7 correspond to the second thickness B of the component in the second region 22. That is, the second gap depth is greater than the first gap depth.

[0083] The second minimum gap width of the second gap is greater than the first minimum gap width of the first gap. In the present case, there are gaps of different widths in the first region 21, which gaps can be defined as first gaps in general. The gap width of the narrower first gaps of these first gaps 19 constitutes the first minimum gap width, which is smaller than the gap width of the second gap 20 with the smallest width. The gap width of the wider first gap 19b can be selected to be less than, equal to or greater than the second minimum gap width. Individual gaps can also have a variable width along their length, in which case the minimum value of this variable width can also be defined as the minimum gap width.

[0084] The first maximum aspect ratio of the first gap 19 is obtained by the ratio of the first gap depth to the first minimum gap width, and the second maximum aspect ratio of the second gap 20 is obtained by the ratio of the second gap depth to the second minimum gap width. The first maximum aspect ratio and the second maximum aspect ratio are of the same magnitude in the embodiment shown. The maximum aspect ratio of the first gap and the maximum aspect ratio of the second gap are respectively greater than 25:1.

[0085] The first structural elements 3 and the second structural elements 2, 7 of the component are designed as plates and are delimited on two mutually parallel opposite sides by first gaps 19 or second gaps 20. At least some of the first structural elements 3 and second structural elements 7 designed as electrode elements are respectively delimited by further first gaps 19 or second gaps 20 extending perpendicularly to the first gaps 19 or second gaps 20 delimiting the parallel sides, so that the corresponding structural elements 3, 7 are connected to the rest of the component on the remaining fourth side.

[0086] The component here comprises a frame 1 and a mass arrangement 4 which can vibrate relative to the frame 1. The frame 1 and the mass arrangement 4 are connected to each other in a vibratory manner via springs 2, that is, they can vibrate relative to each other when the springs 2 are deformed. This vibrability exists in one, two or three spatial directions.

[0087] As described above, the first gap 19 delimits at least some of the first structural elements 3 in such a way that three of its sides are exposed and a fourth side is connected to the rest of the component. In the embodiment shown, this is achieved in that some of the first structural elements 3 are connected to the mass arrangement system 4, while the remaining structural elements are connected to the frame 1 or to an anchoring structure 27 that is fixedly arranged or can be fixed relative to the frame. The electrode elements of the electrode that are separated from each other by the first gaps or the first gaps and connected to different sections or parts of the component are arranged to be interlocked or meshed with each other. That is, these electrode elements partially overlap each other, so that the overlapping area constitutes the electrode of the capacitor. When the mass arrangement system 4 vibrates relative to the frame 1 or the anchoring structure 27, the electrode elements connected to the corresponding section or part vibrate accordingly. Through this vibration, the gap spacing between two adjacent electrode elements changes, and / or the overlapping area of ​​two adjacent electrode elements changes, which leads to a measurable change in the capacitance of the capacitor structure formed by the electrode 3.

[0088] Like the first electrode elements of the first electrode 3 formed by the first structural elements, the second electrode elements of the second electrode 7 formed by the second structural elements can be separated from each other by the second gaps 20 extending between them or the second gaps 20 extending between them, where some second electrode elements are connected to the mass arrangement system 4 and other electrode elements are connected to the frame 1 or to an anchoring structure 27 that is fixedly arranged or can be fixedly arranged relative to the frame 1. The second electrode elements connected to the mass arrangement system 4 can vibrate accordingly relative to the second electrode elements connected to the frame 1 or the anchoring structure 27, which are arranged to be interlocked with each other relative to the other electrode elements.

[0089] The component may also include a second structural element 7 which is designed as a damping element 7 , the design of which is similar to that of the second electrode 7 , but which differs from the latter in its function.

[0090] The first structural element 3 has a structural width extending between two parallel first gaps 19, the minimum structural width of the first and second structural elements being, for example, between 1 μm and 10 μm. The first minimum gap width in the first region is here between 0.3 μm and 1.5 μm, while the second minimum gap width is greater than the first minimum gap width and is between 1.5 μm and 4 μm.

[0091] In addition to the first region 21 with the first thickness C and the second region 22 with the second thickness B, the component also includes a third region 23 with a third thickness A. Here, the third thickness A is also greater than the second thickness B. The second region 22 is defined by a second recess 5 in the back of the micromechanical component, through which the thickness is reduced relative to the third region A and the second region 22 is formed. The first recess 6 is introduced into the second region 22 again to form the first region 21. The third region 23 is such a region, the frame 1 and the anchoring structure 27 or each of the anchoring structures 27 extend mainly in this region. Some parts of the frame 1 are also formally located in the second region 22 here, because these parts have the second thickness B. Therefore, the third region A is contained by the frame 1 and the anchoring structure 27.

[0092] To fix the component to the base body, the third region 23 is connected to the base body 15 on the bottom side. The frame and / or anchoring structure 27 of the component is connected to the base body on the top and / or bottom side. An insulating layer 13 is provided between the component and the base body 15 in the fixing region.

[0093] As mentioned above, the component and the base body 15 are made of single crystal silicon. The component can also be made of an electrically insulating glass material or ceramic material, for example, which should be compatible with silicon in terms of thermal properties. In this case, the insulating layer 13 can be omitted.

[0094] The task of providing a component with high performance and as small a (capacitive) gap spacing as possible is achieved in the component shown in that regions 21, 22, 23 with different structural thicknesses are formed inside the component. The functional elements 2, 3, 7 in the MEMS are bounded by gaps 19, 20 of different widths according to their functions and are assigned to the regions 21, 22, 23 so that the maximum aspect ratio achievable in etching technology can be utilized as well as possible. As a result, the capacitive sensitivity and the oscillating mass / mass (seismische Mass) and the lateral stiffness can be increased independently of each other. While maintaining the maximum possible aspect ratio achievable in etching technology, the structural thickness in the first region 21 where the electrode 3 with the highest sensitivity is located is reduced. The first gap 19 thus constructed as an electrode gap can be realized in this region with a size of <1 μm.

[0095] In the same way, the structural thickness in the region of the mass element 4 and the spring 2 can be designed to be significantly greater. This makes it possible to achieve a structure with a large oscillating mass, which increases the signal-to-noise ratio (SNR), and / or with a high transverse stiffness, which can suppress unwanted movements. These two aspects are necessary and advantageous in particular for the design of high-precision micromechanical inertial sensors, but the basic principle can also be transferred to other sensor and actuator functions.

[0096] exist Figure 2 In the example of a one-dimensional MEMS structure, a possible embodiment of the invention is described, for example, in the form of an acceleration sensor. However, the technology described is not limited to such a system. Figures 3 to 9 Several further possible embodiments are shown in FIG. 1 , without these figures providing an exhaustive list.

[0097] The MEMS structure is preferably made of a monocrystalline silicon substrate and has a surrounding frame with a third thickness A, a mass element 4 (oscillating mass) and at least one suitable spring 2 or spring system with a second thickness. With this second thickness B, the second structural element 7, such as a plate-shaped element, can be designed for electrostatic force input, for capacitive detection or for adjusting damping. Figure 2 This is shown in the example of a damping element 7. The second structural element 7 in this second region 22 with a second thickness B is delimited by a second gap 20 with a second minimum width. In addition, a first region 21 with a further reduced first structural thickness C is formed, which can be equipped with further first structural elements, such as additional spring systems, regions of inertial masses, plate-like elements for electrostatic force input, for capacitive detection or for adjusting damping. Figure 2, a detection electrode 3 with a reduced first thickness C is shown by way of example. A first gap 19 with a first minimum width delimiting the detection electrode is significantly smaller than a second gap 20. The respective maximum aspect ratios resulting from the respective minimum gap widths and the corresponding structure thicknesses present in the respective regions in both regions are selected such that they are approximately equal and correspond to aspect ratios achievable using etching technology.

[0098] In an exemplary possible configuration of the gap spacing and the corresponding structure thickness, assuming a maximum aspect ratio of 25:1, a minimum gap width of 2 μm is achieved, for example, in the second region 22 with a structure thickness of 50 μm, and a minimum gap width of 1 μm is achieved in the first region 21 with a structure thickness of 25 μm. Thus, a doubling of the capacitive sensitivity is already achieved in this example.

[0099] This principle of equalizing the maximum aspect ratio by matching the gap width to the structure thickness is implemented in Figure 2 In the figure, the additionally lowered first region 21 is used as an example, but this is not limited to the stepped structure.

[0100] The described MEMS structure is fixed in a third region 23 having a third thickness A to a lower substrate which is made of an electrically insulating material or is coated with an electrically insulating material 13, such as SiO, for example. 2 Coating. With possible upper substrate (see Figures 6 to 9 ) is formed in the third region 23 on the upper side of the component.

[0101] exist Figure 2 The production of the component or MEMS shown in one of the figures or the following figures is carried out by etching, for example dry etching.

[0102] exist Figure 2 In the case of the component shown, the second recess 5 is first introduced into the lower side of the blank, so that the blank obtains a reduced thickness at the location where the second recess 5 extends. Then, the first recess 6 is introduced within the second recess 5 in order to further reduce the thickness. That is, after the introduction of the two recesses 5, 6, there are three non-intersecting areas 21, 22, 23 with mutually different thicknesses. These three different thicknesses can be thicknesses C, B, A, but can also be three thicknesses that are respectively greater than the thicknesses C, B, A by a certain value, where the thickness of the blank is reduced starting from the upper side in a subsequent step, thereby forming the thicknesses C, B, A.

[0103] The first gaps 19 are etched in the first region 21 and the second gaps 20 are etched simultaneously in the second region 22 in the z direction from the top side. This is preferably done after the blank or component 16 has been arranged on the base substrate 15. For etching, a mask is provided on the top side of the blank, which mask predetermines the position, course and width of all gaps. That is, the mask, for example a resist mask or a hard mask, predetermines the geometrical dimensions of the first gaps 19 and the second gaps 20 in the xy plane perpendicular to the z direction or etching direction.

[0104] The mask is designed and positioned on the top side in such a way that the narrowest gaps are located in the first region, while the widest gaps, which define, for example, the damper 7 or the spring 2, are located in the second region 22. This means that the positions of the recesses are taken into account when positioning the mask. Tolerances can be provided here, for example by making the first recess 6 and / or the second recess 5 slightly larger, so that the positioning of the mask in the x-direction and / or in the y-direction can be achieved with an accuracy of, for example, 5 to 10 μm. All gaps 19, 20 are then etched simultaneously in one step starting from the top side in the z-direction towards the bottom side until they have completely penetrated the blank and are present on the bottom side.

[0105] As mentioned above, the blank or component 16 is usually arranged on the bottom substrate 15 before the gaps 19, 20 are introduced and connected to the bottom substrate by wafer bonding. Here, the connection is established in the third region 23 with a third thickness A, that is, between the frame 1 and the base 15 or between the anchoring structure 27 and the bottom substrate 15.

[0106] Figure 3 ac is limited to showing the MEMS functional layer in different embodiments, that is to say only the components without the base body are shown. In all the embodiments shown here, the first recess 6 and the second recess 5 are present.

[0107] Here, in Figure 3 In a, an electrode 3 with high sensitivity is arranged in the first region, and only a spring 2 is arranged in the second region. A mass element 4 is arranged between the electrode 3 and the spring 2. A larger part of the mass element 4 extends in the second region 22 and has a second thickness B, while a smaller part of the mass element 4 extends into the first region 21 and has a first thickness C.

[0108] exist Figure 3 b, in addition to the spring 2, a damper 7 is also provided in the second region 22. Figure 3 The example in a is different. Figure 3 c shows such an embodiment, which is similar in structure to Figure 3b, in which the structural element designed as spring 8 in the second region 22 is present with a height or thickness in the z direction which decreases from the bottom. For this purpose, the thickness of the component is reduced from the back in the second region 22 where springs 2, 8 are provided. This can be done in particular simultaneously with the introduction of the first recess 6 by etching with the aid of a corresponding mask provided on the bottom side of the blank. In this case, the first recess 6 and the depression for reducing the height of the spring 8 can be etched simultaneously. As a result, the spring 8 generally obtains the same height or thickness as that which is also present in the first region 21, as is also shown in this figure.

[0109] Figure 4 ac show embodiments in which the height of several first and / or structural elements is reduced by etching starting from the top. Figure 4 In a, the electrode element 9 is shown in a first region 21, lowered from the top, which now has a fifth thickness or height E, and the damping element 10 is shown in a second region 22, lowered from the top, which has a fourth height D. In the embodiment shown, the spring 2 has its full height, which corresponds to the second height B.

[0110] exist Figure 4 b, and Figure 4 a, the damper 11 is lowered on both sides, that is, from the top and from the bottom. This damper 11 lowered on both sides also has a fifth height E. Figure 4 c, with Figure 4 Unlike a and b, the spring also decreases in height on both sides and has a fifth height E.

[0111] This step structure of the structural elements 9, 10, 11, 12 starting from the top side is also achieved by etching, where a two-stage mask is applied to the top side, which mask, for example, includes a hard mask and a resist mask. In this case, the etching of the gaps 19, 20 and the reduction in height of the structural elements 9, 10, 11, 12 can be achieved in a two-stage etching process.

[0112] In summary, this means that, by means of the additional height reduction, for example, the following structural elements are produced (see Figure 3 c. Figure 4 ac):

[0113] - Spring 8 forming a step from below

[0114] - Electrode element 9 with the highest sensitivity formed from above

[0115] - Damping element or electrode element 10 formed with a step from above

[0116] - Damping element or electrode element 11 formed with steps on both sides

[0117] - A spring 12 formed with steps on both sides.

[0118] These structural elements 8, 9, 19, 11, 12 can thus be optimally adapted to their respective functions. Thus, springs 8, 12 that are stepped on one side or on the top side, for example, make it possible to easily dimension vertical motion forms. These motion forms can, for example, be advantageously excited electrostatically or detected capacitively by means of electrodes 9 that are stepped on one side or on both sides. Thus, MEMS elements for multi-axis sensors or actuators can be advantageously combined or integrated in one substrate.

[0119] The reduction of the structure thickness in the region of the electrode 3 with higher sensitivity is achieved by an additional etching step according to the described technology. The thickness ratio is designed in such a way that the ARDE between structures with larger gap widths and structures with the smallest gap spacing is used in a targeted manner. The gap length is also adapted in a targeted manner here; very long narrow gaps are interrupted by intentionally introducing widenings, for example, by increasing the gap width locally. This makes it possible to determine the lateral structure dimensions of all functional elements in one etching step, thereby achieving the best possible structural integrity.

[0120] In order to achieve Figure 4 The additional lowering of several functional elements (e.g., springs, fixed or movable capacitor electrodes) shown in ac can use a two-stage structuring process (preferably a two-stage etching process) from the upper side of the blank. For this purpose, a combination of two pre-structured mask layers can be used. After the pre-etching step is carried out at a determined depth, the upper mask layer is removed and etching is continued to establish the desired height step structure. This two-stage method can be advantageously combined with a step-forming process (introducing the first recess 6 and the second recess 5) from the back.

[0121] Figure 5 A schematic cross-sectional view of a component arranged on a base body 15 is shown, which has a protective layer arranged on the underside.

[0122] Optionally, such a protective layer 14, for example SiO2 optimized in thickness, can be placed after etching the first recess 6 and, if present, the second recess 5. 2 The protective layer 14 is arranged on the back side of the blank. The protective layer 14 can prevent overetching in the area of ​​large gaps. This protective layer thus protects the bottom side of the blank from etching and also prevents undesired movement of the structure during etching. The protective layer 14 can be selectively ( Figure 6 ) or completely ( Figure 7 ) and remove it again.

[0123] Figures 6 to 9 Also shown are schematic transverse sectional views of MEMS designed differently according to the present application, each of which has a bottom base body 15 and a top base body 17 .

[0124] The MEMS structure is sealed tightly by the bottom base body 15 and the top base body 17 and a characteristic internal pressure is established.

[0125] As mentioned above, Figure 6 Here we show the later stages Figure 5 16, the top base 17 is now fixed to the component 16 and the protective layer is interrupted at the lower end of the gaps 19, 20 to enable the movability of the structural elements 2, 3. Figure 7 In the embodiment of FIG. 1 , the protective layer 14 is completely removed.

[0126] exist Figure 6 and 7 In the embodiment, the insulating layer 13 is provided between the bottom substrate 15 and the member 16 and between the top substrate 17 and the member 16 in contact regions constituting the third region 23 and having a third thickness (A), respectively.

[0127] Here, in Figure 6 and 7 In the embodiment of the present invention, the contact region is defined towards the bottom base body 15 by the third region 23 and the third thickness A itself and is thus provided by the second recess 5. This means that the mass arrangement 4, the spring 2 or the electrode 3 are prevented from coming into contact with the bottom base body 15 and thus being restricted in their mobility by the second recess 5. With respect to the top base body 17, such a restriction of mobility is prevented by the recess 18 introduced into the top body 17 itself. The depth of the recess 18 can be, for example, 2 to 50 μm.

[0128] exist Figure 8 The embodiment shown here is similar to Figure 6 , 7The difference between the embodiment of is the lack of the second recess 5. Accordingly, the first recess 6 is only present on the underside of the component 16. In this embodiment, the effect of ARDE can also be utilized when manufacturing the component 16. Here, only the step of introducing the second recess 6 is omitted. Accordingly, there is no third region 23 with the third thickness C, but only the first region 21 and the second region 22. The frame 1 and the possible anchoring structure 27 now have the second thickness B and are connected to the bottom substrate 15 and / or the top substrate 17 in the contact area which is also located in the second region 22. In order to ensure movability relative to the bottom substrate 15, the bottom substrate 15 also has a cavity 18 and thus compensates for the missing second recess 5. The cavity 18 in the bottom substrate can also have a depth of 2 to 50 μm. Thus, as Figure 6 and 7 The top base 17 is realized as in the embodiment in FIG.

[0129] Fig. 9 A schematic cross-sectional view of a larger portion of a finished MEMS structure is shown.

[0130] This component also has a first recess 6 and a second recess 5, so that the cavity 18 can be omitted in the bottom base 15, while the top base 17 has a cavity 18. Due to the design of the cavity 18, the fixing area of ​​the component 16 to the bottom base 15 is different from the fixing area of ​​the component to the top base 17: the bottom area 17 is connected to the frame 1 and the anchoring structure 27, while the top base is only connected to the frame 1.

[0131] The bottom substrate 15 has a contact opening or contact hole 25, which allows access to the third fixed area 23, which is located here on the anchoring structure 27. However, in another embodiment, the contact opening 25 can alternatively or additionally also be located in the region of the frame 1. However, alternatively or additionally, there can also be a contact opening in the top substrate 17, which allows access to the fixing area 24. In the case of a conductive or semiconductive base material, the fixing area and the base surface of the bottom substrate 15 and / or the top substrate 17 are also coated in the region of the contact opening 25 with an electrically insulating insulating layer, for example SiO 2 The contact openings 25 and the surface regions, on the other hand, have an electrically conductive, for example metallic, layer 26, which establishes electrical contact with the structures of the MEMS, for example the electrodes 3, and simultaneously enables rewiring (connecting different internally separated MEMS regions to one another and providing contact surfaces for external connections). In this way, the electrodes 3, 7 can be connected and the capacitance changes of the capacitor formed by the electrodes 3, 7 due to vibrations can be detected or measured during operation.

[0132] For manufacturing, for example Fig. 9The method for producing a MEMS element shown in FIG. 1 based on extended cavity SOI technology comprises, for example, the following process steps:

[0133] i. providing a bottom substrate (15) with an electrically insulating layer (13) if necessary,

[0134] ii. providing a blank having a thickness greater than the third thickness (A),

[0135] iii. introducing a second recess (5) into the underside of the blank, preferably by etching,

[0136] iv. introducing at least one first recess (6) into the underside of the blank, preferably by etching, said first recess being located within the second recess (5),

[0137] v. in a fixing area (23), the blank is mounted on the base substrate (15), preferably by wafer bonding,

[0138] vi. Thinning the blank starting from the top side so that a first thickness (C) is established in at least one first region (21), a second thickness (B) is established in a second region (22), and a third thickness (A) is established in a third region or fixing region (23),

[0139] vii. applying a mask layer to the top side of the blank and structuring the mask layer, the mask layer preferably being a resist mask or a hard mask in order to define all lateral dimensions of the micromechanical structure, viii. structuring the micromechanical functional layer starting from the top side in the vertical direction with the aid of the mask layer, preferably by vertical anisotropic dry etching, thereby producing vertical gaps (19, 20) and completing the entire structure in one step,

[0140] ix. Removing the mask layer,

[0141] x. encapsulating the component (16) with a further substrate as a top substrate (17), preferably by wafer bonding, the top substrate having at least one cavity (18) and, if necessary, an electrically insulating layer (13),

[0142] xi. Producing, in the bottom base body (15) and / or in the top base body (17), possibly electrically insulating contact openings (25) between the base body and the structural elements (2, 3) of the component (16) and providing electrically conductive (metallic) connections (26).

[0143] In addition, the present application relates to the following aspects which are helpful for understanding the present invention:

[0144] 1. Micromechanical systems with oscillating spring-mass arrangements,

[0145] · including a bottom substrate and / or a top substrate for fixing the micromechanical structure and fixing the electrode and damper system,

[0146] comprising at least one mass element (4) and a spring combination (2, 8, 12), which allows a degree of freedom of movement in at least one spatial direction and optionally in a maximum of three spatial directions,

[0147] A plate-shaped element with a straight or curved geometry, which is coupled to a movable mass and / or a fixed and electrically insulating region and thereby forms an electrode arrangement system in order to realize electrostatic excitation / force coupling or capacitive detection or in order to realize fluid damping (3, 7, 9, 10, 11), wherein:

[0148] The structure has at least two thinned regions with characteristic recesses (5), (6) towards the substrate and the resulting structure thickness (B, C) and the correspondingly resulting minimum gap spacing (20, 19), wherein in both regions the maximum aspect ratio of the gap width to the structure thickness is approximately equal.

[0149] 2. A micromechanical system according to claim 1, wherein:

[0150] The micromechanical system is made of single crystal Si, and / or

[0151] The substrate is made of single-crystal Si or a glass material or a ceramic material that is thermally compatible with Si.

[0152] 3. A micromechanical system according to claim 1 or 2, wherein:

[0153] A typical structure height (B) is chosen in the range 20...100 μm and a typical maximum aspect ratio is chosen to be >20, and

[0154] Minimum gap spacing (19) is achieved in the range of 1 μm and less.

[0155] 4. A micromechanical system according to any one of aspects 1 to 3, wherein:

[0156] the maximum aspect ratio and the overlap length of the electrodes are chosen such that the entire structure can be produced using only an anisotropic dry etching process, where the etching time for completing the structure is approximately the same in both structure thickness regions,

[0157] 5. A micromechanical system according to any one of aspects 1 to 3, wherein:

[0158] The electrodes are designed to have varying pitch and varying area.

[0159] 6. A micromechanical system according to any one of aspects 1 to 5, wherein:

[0160] The springs, electrodes and dampers can have further steps in two structural thickness regions, resulting in a structural thickness (D, E), in order to be able to generate and detect vertical movements.

[0161] 7. A method for manufacturing a micromechanical system according to one of aspects 1 to 5, comprising at least the following steps:

[0162] providing a substrate (15), which preferably has an electrically insulating layer (13),

[0163] providing a blank for the component (16),

[0164] introducing a first recess (5) into the underside of the blank, preferably by etching,

[0165] introducing a second recess (6) into the underside of the blank, preferably by etching, said second recess being located within the first recess (5),

[0166] In the fixing region (23), the blank is mounted on the base body (15), preferably by wafer bonding,

[0167] thinning the blank from the top so as to establish an edge thickness (A) in the fixing region, a first structural thickness (B) in the first region (22), and a second structural thickness (C) in the second region (21), which is located within the region (22),

[0168] applying a mask layer onto the upper side of the blank and structuring the mask layer, said mask layer preferably being a resist mask or a hard mask, in order to determine all lateral dimensions of the micromechanical structure,

[0169] The micromechanical functional layer is preferably structured in the vertical direction starting from the top by vertical anisotropic dry etching with the aid of a mask layer, whereby vertical gaps (19, 20) are produced and the entire structure is completed in one step,

[0170] Remove the mask layer,

[0171] encapsulating the component (16) with a further base body (17), preferably by wafer bonding, the further base body having at least one further recess (18) and, if appropriate, an electrically insulating layer (13),

[0172] A possibly electrically insulating access opening to the functional region of the sensor structure is produced in the lower base body (15) or the upper base body (17) and a metallic connecting structure is provided.

[0173] 8. A method for producing a micromechanical system according to one of the aspects 1 to 5 or a method according to aspect 7, wherein:

[0174] A protective layer (14) is applied to the underside of the prestructured blank and / or to the upper side of the blank, the thickness of which is selected such that a masking effect is achieved for a limited etching time and thus protection of the surface from etching is achieved.

[0175] 9. A method for producing a micromechanical system according to one of aspects 1 to 5 or a method according to aspect 7 or 8, wherein:

[0176] Instead of introducing the second recess (5) into the underside of the blank, a recess (18) is introduced into the upper side of the base body (15).

[0177] 10. A method for producing a micromechanical system according to one of aspects 1 to 6 or a method according to aspect 7 or 8, wherein:

[0178] To determine the lateral dimensions, a two-stage mask is used, preferably consisting of a hard mask and a resist mask,

[0179] In a first structuring step of the micromechanical functional layer, all gaps are initially pre-etched in the vertical direction by a certain value,

[0180] Thereafter first only the upper mask layer is removed,

[0181] the structuring of the micromechanical functional layer is preferably continued by anisotropic dry etching, wherein a defined lowering of the springs, electrodes and dampers is achieved from the top and structure thicknesses (D) and (E) are established in these regions,

[0182] • Next the hard mask is removed.

[0183] Reference numerals list

[0184] (1) Framework

[0185] (2) Spring (second structural element)

[0186] (3) First electrode (first structural element)

[0187] (4) Quality layout system

[0188] (5) Second recess

[0189] (6) First recess

[0190] (7) Second electrode or damper (second structural element)

[0191] (8) Spring forming a step

[0192] (9) Electrode element forming a step

[0193] (10) Electrode element or damping element forming a step

[0194] (11) Electrode element or damping element with steps formed on both sides

[0195] (12) Spring with steps on both sides

[0196] (13) Insulation layer

[0197] (14) Protective layer

[0198] (15) Bottom substrate

[0199] (16) Component

[0200] (17) Top base

[0201] (18) Cavity in the top or bottom substrate

[0202] (19) First gap

[0203] (20) Second gap

[0204] (21) First Area

[0205] (22) Second Area

[0206] (23) Third Area

[0207] (24) Fixed area with upper substrate

[0208] (25) Contact port of base body

[0209] (26) Conductive layer

[0210] (27) Anchoring mechanism

[0211] (A) Third thickness / height / gap depth

[0212] (B) Second thickness / height / gap depth

[0213] (C) First thickness / height / gap depth

[0214] (D) Fourth thickness / height

[0215] (E) Fifth thickness / height

Claims

1. A component (16) for a micromechanical system, the component having a top side and a bottom side opposite the top side, the component comprising: - several first structural elements, which are arranged in a first region (21) of the component (16) and are delimited by at least one first gap (19); - at least one second structural element, which is arranged in a second region (22) of the component (16) different from the first region (21) and is delimited by at least one second gap (20); wherein the first region (21) is defined by a first recess (6) in the underside of the component (16) and a first thickness (C) of the component (16) in the first region (21) is reduced relative to a second thickness (B) of the component (16) in a second region (22); wherein the at least one first gap (19) extends from the upper side to the lower side in the first region (21) and ends in the first recess (6), and has a first gap depth defined by a first thickness (C) of the component (16) in the first region; wherein the at least one second gap (20) extends from the upper side to the lower side in the second region (22) and ends outside the first recess (6), and has a second gap depth defined by a second thickness (B) of the component (16) in the second region (22), the second gap depth being greater than the first gap depth of the first gap (19); and wherein the second minimum gap width of the at least one second gap (20) is greater than the first minimum gap width of the at least one first gap (19); and The component also includes a frame (1) and a mass arrangement system (4) that vibrates relative to the frame (1), wherein the at least one first gap (19) extends between the mass arrangement system (4) and the frame (1) or between the mass arrangement system (4) and an anchoring structure (27) that is fixedly arranged or can be fixedly arranged relative to the frame (1), so that the several first structural elements defined by the at least one first gap (19) include a first electrode (3), the first electrode (3) includes a fixed electrode element connected to the anchoring structure (27) or the frame (1) and the first electrode (3) includes a movable electrode element connected to the mass arrangement system (4), wherein the fixed electrode element connected to the anchoring structure (27) or the frame (1) and the movable electrode element connected to the mass arrangement system (4) are engaged with each other and can move relative to each other.

2. The component (16) according to claim 1, wherein A first maximum aspect ratio of the at least one first gap (19) is given by a ratio of a first gap depth to a first minimum gap width; A second maximum aspect ratio of the at least one second gap (20) is given by a ratio of a second gap depth to a second minimum gap width; The first maximum aspect ratio is equal to or substantially equal to the second maximum aspect ratio.

3. A component (16) according to claim 1 or 2, wherein: The at least one first structural element is delimited by the at least one first gap (19) at least on two opposite sides extending at least partially parallel to each other and / or the at least one second structural element is delimited by the at least one second gap (20) at least on two opposite sides extending at least partially parallel to each other and so that the at least one first structural element or the at least one second structural element is configured as a straight or curved plate.

4. A component (16) according to claim 1 or 2, wherein: First gaps (19a, 19b) of different widths are provided in the first region (21).

5. The component (16) according to claim 1, comprising a frame (1) and a mass arrangement system (4) which can vibrate relative to the frame (1), wherein: The at least one second structural element comprises an elastic spring (2) which connects the frame (1) and the mass arrangement system (4) to one another in such a way that the frame and the mass arrangement system can vibrate relative to one another when the spring (2) is deformed.

6. A component (16) according to claim 1 or 5, wherein: The at least one second gap (20) extends between the mass arrangement system (4) and the frame (1) or between the mass arrangement system (4) and an anchoring structure (27) fixedly arranged or fixable relative to the frame (1), so that the at least one second structural element defined by the at least one second gap (20) includes a second electrode (7) or a damper, the second electrode or damper and an electrode element connected to the anchoring structure (27) or the frame (1) and the second electrode or damper includes an electrode element connected to the mass arrangement system (4), the electrode element connected to the anchoring structure (27) or the frame (1) and the electrode element connected to the mass arrangement system (4) are mutually engaged and can move relative to each other.

7. A component (16) according to claim 1 or 2, wherein: The first minimum gap width of the at least one first gap is at least 0.1 µm and / or at most 3 µm, and / or the second minimum gap width of the at least one second gap is at least 1.5 µm and / or at most 4 µm.

8. A component (16) according to claim 1 or 2, wherein: The first thickness (C) is at least 5 µm and / or at most 100 µm; and / or the first thickness (C) corresponds to at least 15% of the second thickness (B).

9. The component (16) according to claim 2, wherein The first maximum aspect ratio of the at least one first gap (19) and the second maximum aspect ratio of the at least one second gap (20) are respectively 10:1 or greater.

10. The component (16) according to claim 1 or 2, wherein: The height of one or more of the at least one first structural element and / or one or more of the at least one second structural element is reduced on the top side and / or on the bottom side relative to the thickness of the corresponding region (21, 22) in which the structural element is arranged.

11. A component (16) according to claim 1 or 2, wherein: The component (16) is made of silicon or contains silicon.

12. The component (16) according to claim 7, wherein The first minimum gap width of the at least one first gap is at least 0.3 µm.

13. The component (16) according to claim 7, wherein The first minimum gap width of the at least one first gap is at most 1.5 μm.

14. The component (16) according to claim 8, wherein The first thickness (C) is at most 60µm.

15. The component (16) according to claim 8, wherein The first thickness (C) corresponds to at least 25% and / or at most 90% of the second thickness (B).

16. The component (16) according to claim 8, wherein The first thickness (C) corresponds to up to 80% of the second thickness (B).

17. The component (16) according to claim 9, wherein The first maximum aspect ratio of the at least one first gap (19) and the second maximum aspect ratio of the at least one second gap (20) are 20:1 or greater.

18. The component (16) according to claim 9, wherein The first maximum aspect ratio of the at least one first gap (19) and the second maximum aspect ratio of the at least one second gap (20) are 25:1 or greater.

19. The component (16) according to claim 11, wherein The silicon is single crystal silicon.

20. A component (16) according to claim 1 or 2, wherein The transverse dimension of the component perpendicular to the thickness direction of the component is between 0.5 mm and 15 mm and / or the transverse dimension of the first recess (6) is between 100 µm and 2000 µm.

21. A component (16) according to claim 1 or 5, wherein The second region (22) is defined by a second recess (5) in the back side of the component (16), and the second thickness (B) is smaller than a third thickness (A) of a third region (23) different from the first region (21) and the second region (22), and the frame (1) and / or the anchoring structure (27) at least partially extends in the third region (23).

22. A micromechanical system, comprising a component (16) according to claim 1 or 5 and a substrate for fixing the component (16), wherein: The frame (1) and / or the anchoring structure (27) of the component (16) is connected to the base body (15, 17) on the top side and / or on the bottom side.

23. The micromechanical system according to claim 22, wherein: The base body is made of silicon and / or of a glass material or a ceramic material which is thermally adapted to silicon.

24. The micromechanical system according to claim 23, wherein: The silicon is single crystal silicon.

25. A method for producing a component (16) for a micromechanical system, the method comprising at least the following steps: Introducing a first recess (6) into the underside of the blank, so that the blank has a first thickness (C) extending in the z-direction in a first region (21) defined by the first recess (6), the first thickness being smaller than a second thickness (B) extending in the z-direction in a second region (22) different from the first region (21); Then, the blank having the first recess (6) is arranged and fixed on a bottom substrate (15); subsequently etching at least one first gap (19) in the first region (21) so as to produce at least one first structural element defined by the at least one first gap (19); as well as etching at least one second gap (20) in the second region (22) to produce at least one second structural element defined by the at least one second gap (20); wherein the etching is respectively performed along the z direction and is performed in such a way that the at least one first gap (19) has a first gap depth defined by the first thickness (C), the first gap depth is smaller than a second gap depth of the at least one second gap (20) defined by the second thickness (B) in the second region (22), and the first minimum gap width of the at least one first gap (19) is smaller than the second minimum gap width of the at least one second gap (20); and The at least one first gap (19) and the at least one second gap (20) are etched into the blank having the first recess (6) along the z direction toward the bottom side starting from the top side of the blank facing away from the bottom side, and the blank is arranged on the bottom substrate (15).

26. The method according to claim 25, further comprising the steps of: A mask is applied to the upper side of the blank and the geometric dimensions of the at least one first gap (19) and the at least one second gap (20) are predetermined by the mask in a plane perpendicular to the z-direction.

27. The method according to claim 26, wherein: The mask is a resist mask and / or a hard mask.

28. The method according to claim 25 or 26, wherein: The at least one first gap (19) and the at least one second gap (20) are etched simultaneously.

29. The method according to claim 25 or 26, wherein: The blank is made of or comprises silicon.

30. The method of claim 29, wherein: The silicon is single crystal silicon, and / or the etching is performed using a dry etching process.

31. The method according to claim 25 or 26, wherein: The second region (22) is defined by a second recess (5) which is introduced into the underside of the blank in a step prior to the introduction of the first recess (6), the first recess (6) being introduced into the blank within the second recess (5).

32. The method according to claim 25 or 26, wherein: In a step after the introduction of the first recess (6) into the blank or in a step after the introduction of the first recess (6) and the introduction of the second recess (5) into the blank, a protective layer (14) is applied at least partially to the underside of the blank.

33. The method of claim 32, wherein: The protective layer (14) is an oxide layer.

34. The method according to claim 25 or 26, comprising the steps of: Starting from the upper side and / or starting from the lower side, the height of one or more of the at least one first structural elements is reduced relative to the first thickness, and / or starting from the upper side and / or starting from the lower side, the height of one or more of the at least one second structural elements is reduced relative to the second thickness, and the steps are respectively performed in an etching process using a two-stage mask, wherein the mask includes a hard mask and a resist mask.

35. The method according to claim 25 or 26, wherein: The blank with the introduced gaps (19, 20) is covered by the top base body (17) and the contact regions of the blank are connected to the bottom base body (15) and / or the top base body (17) by means of a wafer bonding connection.

36. The method of claim 35, wherein: The contact area of ​​the blank is the frame (1) and / or the anchoring structure (27).

37. The method of claim 35, wherein: An insulating layer (13) is provided in at least one of the contact regions between the micromechanical component and the bottom substrate (15) and / or the top substrate (17), and / or a cavity is introduced into the bottom substrate (15) and / or the top substrate (17) outside the contact region on the side of the bottom substrate (15) or the top substrate (17) facing the component (16) before fixing.

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