Microelectromechanical component with vertical stop

Abstract

Microelectromechanical component (1), wherein the microelectromechanical component (1) comprises a substrate device (2), a first, a second and a third functional layer (3, 4, 5) spaced vertically apart from each other, wherein a vertical stop (6) is formed between the second and third functional layer (4, 5), wherein the vertical stop (6) has a stop area (7) on a surface of the second functional layer (4) facing the third functional layer (5), characterized in that the second functional layer (4) is connected to the first functional layer (3) in a connection area (8) associated with the stop area (7), wherein the second functional layer (4) has a frame (11) enclosing an area in the connection area (8).

Description

State of the art

[0001] The invention is based on a microelectromechanical component according to the preamble of claim 1.

[0002] Microelectromechanical components are well known. For example, microelectromechanical sensors (MEMS) are used to measure accelerations and angular rates in a wide variety of applications. Such microelectromechanical sensors generally have several movable structures connected to the sensor substrate via springs. These movable structures can be arranged in a functional layer between the substrate and the cap device. However, when MEMS sensors are used, in addition to the accelerations and angular rates to be measured, overload accelerations also always occur. Various mechanical concepts are known to prevent damage to the MEMS sensor, especially to the movable structures of the sensor, due to overload accelerations. For example, lateral movement can be limited by lateral stop knobs.The lateral stop studs define fixed stop points within which movement of the movable structure does not lead to damage to the MEMS sensor and limit the stresses between the movable structure and its suspension caused by overload acceleration. Upper and lower stops are known to limit vertical movements out of the functional layer. These are designed as stop studs on the cap or on the substrate arranged beneath the functional layer. Analogous to the lateral stops, the vertical stops limit the freedom of movement of the movable structure in the vertical direction and establish a defined stop point to prevent damage to the MEMS sensor. The upper and lower vertical stops can only be used if there is a gap between the movable structure to be secured and the cap device orthere is no further functional layer between the movable structure to be protected and the substrate device.

[0003] Further microelectromechanical components are known from the documents DE 199 06 046 A1 and EP 2 860 990 B1. Disclosure of the invention

[0004] It is an object of the present invention to propose a microelectromechanical component with a plurality of functional layers arranged between the substrate and cap device, which has an increased robustness compared to microelectromechanical components known from the prior art.

[0005] The microelectromechanical component according to the invention according to the main claim has the advantage over the prior art that even vertical downward movements of a third functional layer are limited by a vertical stop. This prevents damage to the microelectromechanical component due to vertical overload accelerations upwards. Thus, a microelectromechanical component with multiple, in particular movable, functional layers is advantageously provided, which is more robust than corresponding components known from the prior art. The distance of the stop can be adjusted by the distance between the second and third functional layers. The distance of the stop is independent of the distance between the first and second functional layers.The distance of the stop is thus determined solely by the geometry and topology of the third functional layer and is thus optimally adapted to it. In the context of the present invention, the term "microelectromechanical component" is to be understood as encompassing both micromechanical components and microelectromechanical components.

[0006] Advantageous embodiments and further developments of the invention can be found in the dependent claims and the description with reference to the drawings.

[0007] According to a preferred development, the stop region and the connection region are only vertically spaced from one another. The stop region and the connection region are preferably arranged on opposite surfaces of the second functional layer. In particular, the stop region is arranged on a surface of the second functional layer facing the third functional layer, and the connection region is arranged on a surface of the second functional layer facing the first functional layer. The stop region and the connection region preferably have essentially identical dimensions. This defines a stop for the third functional layer on the first and second functional layers which are firmly connected in the stop region. The independent functionalization and mobility of the first and third functional layers is only achieved within the very narrowly defined connection orThe independent functionality of the first, second, and third functional layers is thus largely retained despite the impact.

[0008] According to a preferred development, the third functional layer has a nub in a region opposite the stop region. The nub is preferably formed on a surface of the third functional layer facing the second functional layer. The base area of ​​the nub preferably has the dimensions of the stop region. The nub can be formed by processing one or more oxide layers on the surface of the third functional layer deposited above it, said surface facing the second functional layer. The thickness of the oxide layers deposited between the second and third functional layers determines the spacing of the vertical stop. The spacing of the vertical stop can thus advantageously be matched to the geometry and topology of the third functional layer.

[0009] According to the invention, the second functional layer has a frame in the connection region. According to a preferred development, the first and second functional layers are connected to one another via an oxide layer arranged between the first and second functional layers in the connection region. In particular, an oxide layer is deposited on the first functional layer. The oxide layer is preferably opened in the region in which the connection region of the second functional layer is to be created. The oxide via thus created in the form of a frame is filled during the deposition of the second functional layer and the oxide is enclosed within the frame. The region of the second functional layer enclosed by the oxide via is firmly connected to the first functional layer. This advantageously provides a fixed vertical stop downwards for the third functional layer.

[0010] According to a preferred development, the second functional layer has a nub in the stop region. In particular, the topography of the surface of the second functional layer facing the third functional layer is determined by the structure of the frame, in particular of the oxide via. Preferably, the surface of the second functional layer facing the third functional layer has a depression in the region of the frame. The region of the surface facing the third functional layer that lies above the interior of the frame thus forms a nub. In this case, the thickness of the second functional layer in the region of the nub is preferably substantially identical to the thickness of the second functional layer outside the stop and connection region. This advantageously provides a fixed vertical stop on the second functional layer that is completely mechanically decoupled from the rest of the second functional layer.

[0011] According to a preferred development, the second and / or third functional layer is movable relative to the substrate device. Preferably, the second and / or third functional layer comprises movable structures. The movable structures can be coupled to one another via spring structures and / or connected to the substrate via spring structures. Preferably, the second and / or third functional layer is movable in the lateral and / or vertical directions.

[0012] According to a preferred embodiment, the microelectromechanical component comprises an acceleration sensor or a rotation rate sensor. In particular, the microelectromechanical component comprises a microelectromechanical sensor, preferably an inertial sensor.

[0013] Embodiments of the present invention are illustrated in the drawings and explained in more detail in the following description. Short description of the drawings

[0014] It shows Fig. 1 a plan view of a vertical stop of a microelectromechanical component according to an embodiment of the present invention in a schematic view, and Fig. 2 shows a cross section of a vertical stop of a microelectromechanical component according to an embodiment of the present invention in a schematic view. Embodiments of the invention

[0015] In the various figures, identical parts are always provided with the same reference symbols and are therefore usually named or mentioned only once.

[0016] In Fig. 1 and Fig.2 shows a schematic view of a top view and a cross section of a vertical stop 6 of a microelectromechanical component 1 according to an embodiment of the present invention. In the region of the stop, the microelectromechanical component 1, for example an inertial sensor, has first, second, and third functional layers 3, 4, 5. The first, second, and third functional layers 3, 4, 5 are vertically spaced from one another and arranged substantially one above the other on a substrate device 2, also called a substrate wafer. The first, second, and / or third functional layers can have a structure. The first functional layer 3 is firmly connected to the substrate device 2. In particular, a first oxide layer 12 is deposited on the substrate device 2. The first functional layer 3 is processed on the first oxide layer 12.The first functional layer 3 is firmly connected to the substrate device 2 via the first oxide layer 12. A second oxide 13 is deposited on the first functional layer 3. The second and third functional layers 4, 5 are processed above this, vertically spaced from one another. The second and third functional layers 4, 5 have movable structures. The movable structures are coupled to one another via springs, for example, and / or connected to the substrate device 2. In particular, the third functional layer 5 is movable in the vertical direction. To prevent damage to the microelectromechanical component 1, a vertical stop 6 is provided between the second and third functional layers 4, 5. The vertical stop 6 limits the upward and downward movement of the third functional layer 5 and defines a contact point below the third functional layer 5.Within the limited movement range defined by this contact point, no damage to the microelectromechanical component 1 occurs. The vertical stop has, on the one hand, a stop region 7 on the upper side, i.e. on a surface of the second functional layer 4 facing the third functional layer 5. The stop region 7 has a circumferential depression 14. The depression 14 preferably encloses an area whose dimensions correspond to the base area of ​​the nub 9 of the third functional layer 5. The area enclosed by the depression 14 forms a nub 10 on the upper side of the second functional layer 4. In particular, the topography of the upper side of the second functional layer 4 is determined by the structure of the oxide layer 13 arranged beneath the second functional layer 4. Preferably, the second oxide layer 13 is opened in the area of ​​the vertical stop 6, so that an oxide via in the form of a frame is created.During the deposition of the second functional layer 4, the oxide via is filled and the oxide 13 located within the frame 11 is enclosed. This determines the topography of the upper side of the second functional layer 4. In particular, the topography of the upper side corresponds to the frame structure of the oxide layer 13. The area of ​​the second functional layer 4 enclosed by the frame 11 is thus firmly connected to the first functional layer 3. This creates a fixed stop area 7 for the third functional layer 5 on the second functional layer 4. The actual function of the second functional layer 4 is only interrupted by the stop 6 and the mobility of the second functional layer 4 is only restricted in the narrowly defined area of ​​the stop 6. The vertical stop 6 has a nub 9 processed on the underside, i.e. on a surface facing the second functional layer 4, of the third functional layer 5.The nub 9 is preferably designed with a rectangular base area. The thickness of the nub 9 determines the spacing of the vertical stop 6. The nub 9 is preferably created by processing and structuring one or more oxide layers on the underside of the third functional layer 5 deposited above it. The spacing can thus advantageously be adjusted according to the requirements and dimensions of the third functional layer 5. In particular, the spacing is independent of the geometries and the relative arrangement of the first and second functional layers 4, 5. By shaping the stop 6 between the second and third functional layers 4, 5, spacing dimensions can be realized depending on the selected thicknesses of the oxide layers arranged between the second and third functional layers 4, 5.This advantageously provides a vertical stop 6 for a microelectromechanical component 1 with multiple movable functional layers. The vertical stop 6 protects, in particular, the third functional layer against vertical downward overload accelerations. This reduces damage to the microelectromechanical component 1 caused by overload accelerations. This advantageously provides a microelectromechanical component 1 with increased robustness compared to the prior art.

Claims

[1] Microelectromechanical component (1), wherein the microelectromechanical component (1) comprises a substrate device (2), a first, a second and a third functional layer (3, 4, 5) spaced vertically from one another, wherein a vertical stop (6) is formed between the second and third functional layers (4, 5), wherein the vertical stop (6) has a stop region (7) on a surface of the second functional layer (4) facing the third functional layer (5), characterized by that the second functional layer (4) is connected to the first functional layer (3) in a connecting region (8) assigned to the stop region (7), wherein the second functional layer (4) has a frame (11) enclosing a region in the connecting region (8). [2] Microelectromechanical component (1) according to claim 1, characterized by that the stop area (7) and the connecting area (8) are only vertically spaced from each other. [3] Microelectromechanical component (1) according to one of the preceding claims, characterized by that the third functional layer (5) has a knob (9) in an area opposite the stop area (7). [4] Microelectromechanical component (1) according to one of the preceding claims, characterized by that the first and the second functional layer (3, 4) are connected to one another via an oxide layer (13) arranged between the first and second functional layer (3, 4) in the connecting region (8). [5] Microelectromechanical component (1) according to one of the preceding claims, characterized by that the second functional layer (4) has a knob (10) in the stop area (7). [6] Microelectromechanical component (1) according to one of the preceding claims, characterized by that the second and / or the third functional layer (3, 4) are movable relative to the substrate device (2). [7] Microelectromechanical component (1) according to one of the preceding claims, characterized by that the microelectromechanical component (1) has an acceleration sensor or a rotation rate sensor. [8] Microelectromechanical component (1) according to one of the preceding claims, characterized by that a fourth functional view or a fourth functional layer and a fifth functional layer are arranged above the third functional layer (5). [9] Microelectromechanical component (1) according to claim 8, characterized by that a sacrificial layer is arranged between the third and fourth functional layer and / or between the fourth and fifth functional layer.

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