Microelectromechanical transducer element and microelectromechanical component with a transducer element

Abstract

The invention relates to a microelectromechanical transducer element (100) with an electrode system (101), comprising at least one first electrode (103), a second electrode (105), and a capsule structure (107), wherein the electrode system (101) is arranged in a receiving space defined by the capsule structure (107), wherein the second electrode (105) is movably mounted in the receiving space (109) relative to the first electrode (103), and wherein the capsule structure (107) provides a fluid-tight encapsulation of the electrode system (101) from an external environment of the transducer element (100). The invention further relates to a microelectromechanical component (200) with a microelectromechanical transducer element (100).

Description

[0001] The present invention relates to a microelectromechanical transducer element and a microelectromechanical component having a microelectromechanical transducer element. State of the art

[0002] Microelectromechanical transducer elements are known from the state of the art.

[0003] It is an object to provide an improved microelectromechanical transducer element and a microelectromechanical component with a transducer element.

[0004] This object is achieved by the microelectromechanical transducer element and the microelectromechanical component of the independent claims. Advantageous embodiments are the subject of the dependent claims.

[0005] According to one aspect, a microelectromechanical transducer element is provided with an electrode system, with at least a first electrode and a second electrode, and with a capsule structure, wherein the electrode system is arranged in a receiving space defined by the capsule structure, wherein the second electrode is mounted in the receiving space so as to be movable relative to the first electrode, and wherein the capsule structure effects a fluid-tight encapsulation of the electrode system from an external environment of the transducer element.

[0006] This allows the technical advantage of providing an improved microelectromechanical transducer element. In the improved transducer element, the electrodes of an electrode system are arranged within a receiving space of a capsule structure. The capsule structure provides fluid-tight protection for the electrode system from the external environment of the microelectromechanical transducer element. This results in a high degree of robustness of the transducer element against contamination by particles or the effects of moisture, particularly on the electrode system. Furthermore, squeeze film attenuation within the electrode system due to fluid penetration into the electrode system can be avoided.

[0007] According to one embodiment, the transducer element further comprises a base structure having a rigid frame element and a movable element, wherein the movable element is resiliently movable relative to the rigid frame element, and wherein the first electrode is fixed to the rigid frame element and the second electrode is fixed to the movable element.

[0008] This achieves the technical advantage that the base structure secures the first and second electrodes of the electrode system and arranges them robustly in the transducer element. The first and second electrodes are arranged so they can move relative to one another, with the first electrode being arranged on the rigid frame element and the second electrode being arranged on the movable element of the base structure. The movable element of the base structure is mounted so that it can move relative to the rigid frame element. The movement of the movable element relative to the rigid frame element causes a relative movement between the two electrodes of the electrode system.

[0009] According to one embodiment, the base structure further comprises at least one spring element, wherein the movable element is resiliently connected to the rigid frame element via the at least one spring element.

[0010] This provides the technical advantage that the spring element connecting the movable element to the frame element provides a resilient, movable suspension of the movable element to the rigid frame element. The spring element also ensures a secure connection between the frame element and the movable element.

[0011] According to one embodiment, the capsule structure comprises at least one support element and an elastically deformable boundary layer, wherein the at least one support element is formed on the base structure, and wherein the receiving space extends the base structure, the at least one support element and the boundary layer.

[0012] This achieves the technical advantage that, through the use of the elastically deformable boundary layer and the support element for spanning the receiving space of the capsule structure, interaction of the transducer element with the external environment of the transducer element is enabled despite the fluid-tight encapsulation of the electrode system from the external environment. Due to the elastic deformability of the boundary layer, pressure waves from the external environment can be transmitted via the elastically deformable boundary layer to the electrodes of the electrode system, or conversely, movements of the electrodes of the electrode system or of the movable element can be transmitted to the external environment via the elastically deformable boundary layer. This allows the transducer element to be used, for example, for a microphone or a loudspeaker.

[0013] To produce the confinement layer, the base structure can first be patterned out of a substrate using a patterning process. Two to three sacrificial oxide layers, an electrode layer, and the confinement layer can be deposited and patterned. The sacrificial layers can be etched through sacrificial layer openings in the confinement layer. Finally, a sealing layer can be deposited.

[0014] According to one embodiment, the receiving space is at least partially fixedly connected to the movable element, wherein the receiving space is moved along with a movement of the movable element relative to the rigid frame element.

[0015] This achieves the technical advantage of ensuring fluid-tightness of the capsule structure by stationary fixation of the receiving space with the movable element. When the movable element moves relative to the frame element, the receiving space is moved along with the frame element. The base structure is thus part of the capsule structure. This facilitates the formation of the receiving space and enables fluid-tight encapsulation of the electrode system formed inside the receiving space.

[0016] According to one embodiment, the first electrode comprises an electrode portion, an anchoring portion and a connecting portion connecting the electrode portion to the anchoring portion, wherein the anchoring portion is anchored to the rigid frame element, and wherein the electrode portion is arranged opposite the second electrode in a region of the movable element.

[0017] This allows for the technical advantage that the anchoring section fixes the first electrode to the rigid frame element. In the area of ​​the electrode section, however, the first electrode is arranged freely suspended within the receiving space and has no contact points with the movable element. This allows for the first electrode to be rigidly fixed to the rigid frame element. This prevents movement of the first electrode within the receiving space despite movement of the movable element.

[0018] According to one embodiment, the second electrode comprises a plurality of second electrode elements formed on the movable element.

[0019] This makes it possible to achieve the technical advantage that the area of ​​the second electrode can be increased by the plurality of second electrode elements fixed to movable elements, whereby the response behavior of the microelectromechanical transducer element can be improved.

[0020] According to one embodiment, the receiving space is filled with a defined gas mixture. This gas mixture can, for example, comprise inert gases such as neon, argon, or nitrogen, or mixtures thereof.

[0021] This provides the technical advantage of arranging the electrode system in the recording chamber in an atmosphere that favors its performance. In particular, long-term robustness and resistance to thermogravimetric effects can be achieved.

[0022] According to one embodiment, the gas pressure of the gas mixture within the receiving space is lower than the atmospheric pressure of the external environment of the transducer element. The gas pressure is adjusted when the receiving space is closed after the sacrificial layer etching. A favorable gas pressure can be in the range of 1-100 mbar, in particular.

[0023] This offers the technical advantage of improving the response of the microelectromechanical transducer element due to the negative pressure of the gas mixture within the receiving chamber relative to the ambient atmospheric pressure. Furthermore, squeeze film damping effects can be largely avoided, making the drive significantly more energy-efficient.

[0024] According to one embodiment, the electrode system further comprises a third electrode.

[0025] This allows the technical advantage to be achieved that the third electrode can provide a bidirectional drive through the microelectromechanical transducer element.

[0026] According to one embodiment, the third electrode is formed on the movable element or on the rigid frame element.

[0027] This makes it possible to achieve the technical advantage that the third electrode can be operated as a fixed electrode according to the first electrode or as a movable electrode according to the second electrode.

[0028] According to one embodiment, at least one electrode of the electrode system forms at least one support element of the capsule structure.

[0029] This makes it possible to achieve the technical advantage that by using at least one electrode of the electrode system as a support element of the capsule structure, support elements can be saved, whereby the capsule structure can be simplified.

[0030] According to one embodiment, the electrodes of the electrode system are designed as comb electrodes, stray field electrodes or as NED electrodes.

[0031] This provides the technical advantage of providing a robust, powerful and reliable electrode system.

[0032] According to one embodiment, the converter element is designed as an actuator element for driving a movement.

[0033] This allows the technical advantage to be achieved that the microelectromechanical transducer element can serve as a transducer element for a loudspeaker.

[0034] According to a further aspect, a microelectromechanical component with at least one transducer element according to one of the preceding embodiments is provided.

[0035] This makes it possible to achieve the technical advantage that an improved microelectromechanical component with at least one microelectromechanical transducer element according to the invention can be provided with the technical advantages described above.

[0036] According to one embodiment, the microelectromechanical component is designed as a loudspeaker.

[0037] This can achieve the technical advantage of providing an improved loudspeaker.

[0038] Embodiments of the invention are described with reference to the following figures. The figures show: Fig. 1 a schematic representation of a microelectromechanical transducer element in plan view according to an embodiment; Fig. 2 a schematic sectional view of the microelectromechanical transducer element of Fig. 1; Fig. 3 shows a further schematic sectional view of the microelectromechanical transducer element according to a further embodiment; and Fig. 4 a schematic representation of a microelectromechanical component with a microelectromechanical transducer element.

[0039] Fig. 1 shows a schematic representation of a microelectromechanical transducer element 100 in plan view according to one embodiment.

[0040] The microelectromechanical transducer element 100 comprises an electrode system 101 with a first electrode 103 and a second electrode 105. The microelectromechanical transducer element 100 further comprises a capsule structure 107 that defines a receiving space 109. According to the invention, the first and second electrodes 103, 105 of the electrode system 101 are arranged in the receiving space 109 of the capsule structure 107. The capsule structure 107 ensures fluid-tight encapsulation of the electrode system 101 from an external environment 111 of the transducer system 100.

[0041] In the embodiment shown, the transducer element 100 further comprises a base structure 113. The base structure 113 comprises a rigid frame element 115 and an element 117 that is movable relative to the frame element 115. In the embodiment shown, the base structure 113 comprises two rigid frame elements 115 arranged opposite one another. The movable element 117 is arranged between the two frame elements 115 and is movable relative to the two frame elements 115.

[0042] The movable element 117 is connected to the two rigid frame elements 115 via a spring element 119 each. In the illustrated plan view of the microelectromechanical transducer element 100, the spring elements 119 between the movable element 117 and the frame elements 115 may be concealed by the receiving space 109 of the capsule structure 107 and thus not visible.

[0043] In the embodiment shown, the first electrode 103 is anchored to the two rigid frame elements 115 via two anchoring points 135.

[0044] The second electrode 105, on the other hand, is connected to the movable element 117 of the base structure 113 via corresponding anchoring points 135.

[0045] In the embodiment shown, the first electrode 103 has two anchoring sections 127. The first electrode 103 is anchored to the two rigid frame elements 115 by the two anchoring sections 127. The first electrode 103 further has an electrode section 125. The electrode section 125 is positioned in the region of the movable element 117 and arranged adjacent to the second electrode 105. The first electrode 103 further has two connecting sections 129. The connecting sections 129 connect the two anchoring sections 127 to the electrode section 125.

[0046] In the embodiment shown, the second electrode 105 has a plurality of second electrode elements 131. The second electrode elements 131 are each fixedly connected to the movable element 117 of the base structure 113 via anchoring points 135.

[0047] The first electrode 103 has a plurality of comb elements 143 in the electrode section 125. The comb elements 143 are connected to one another via a connecting web 145. The connecting web 145 merges into the connecting section 129. The comb elements 143 of the first electrode 103 are each arranged opposite the second electrode elements 131.

[0048] In the embodiment shown, the first and second electrodes 103, 105 of the electrode system 101 are designed as comb electrodes.

[0049] Alternatively, the electrodes 103, 105 could also be designed as stray field electrodes or as NED electrodes.

[0050] In the embodiment shown, the capsule structure 107 comprises at least one support element 121 and a further elastically deformable boundary layer 149. The further boundary layer 149 is formed on the frame elements 115, the movable element 117 as well as the spring elements 119. The first electrode 103 and the second electrode 105 are arranged above the further boundary layer 149. The capsule structure 107 further comprises a boundary layer 123, which in Fig. 1 is not shown, as this is in the top view of the Fig. 1 would be arranged above the electrodes 103, 105 and would thus cover them.

[0051] The support element 121 is in the embodiment in Fig. 1 is formed as a border structure and is connected to the frame elements 115, the movable element 117, and the spring elements 119. In the embodiment shown, the support element 121 has a direct connection to the further boundary layer 149.

[0052] By the base structure 113, in particular by the frame elements 115, the movable element 117 and the spring elements 119, by the support element 121 and the Fig. In the embodiment shown, the receiving space 109 of the capsule structure 107 is spanned by a boundary layer 123 not shown in FIG. 1 .

[0053] Due to the support element 121 designed as a border structure, which is formed on the two frame elements 115, the movable element 117 and the spring elements 119 and borders the electrode system 101, the receiving space 109 of the capsule structure 107 has an electrode region 137, two anchoring regions 139 and two connecting regions 141.

[0054] The electrode region 137 is arranged on the movable element 117 and comprises the electrode section 125 of the first electrode 103 and the entire second electrode 105. The anchoring regions 139 are each arranged on the two rigid frame elements 115 and comprise the anchoring sections 127 of the first electrode 103. The connecting regions 141 are formed on the spring elements 119 of the base structure 113 and comprise the connecting sections 129 of the first electrode 103.

[0055] In the embodiment shown, the receiving space 109, in particular the electrode region 137, is fixedly connected to the movable element 117. When the movable element 117 moves relative to the rigid frame elements 115, the electrode region 137 of the receiving space 109 is thus moved along with the movable element 117. The positioning of the second electrode 105, which is fixed to the movable element 117, within the electrode region 137 of the receiving space 109 remains unchanged during the movement of the movable element 110. However, when the movable element 117 moves, a relative movement occurs, in particular of the electrode section 125 of the first electrode 103, relative to the movable element 117 and also relatively within the electrode region 137 of the receiving space 109.

[0056] In the embodiment shown, the spring elements 119 have an angled structure. The angled structure creates a restoring force that enables the resilient suspension of the movable element 117 relative to the rigid frame elements 115. In the embodiment shown, the connecting section 129 of the first electrode 103 follows the course of the angled spring elements 119 and also has an angled course. Accordingly, the receiving space 109 connected to the spring element 119 has a corresponding angled course in the connecting region 141.

[0057] Fig. 2 shows a schematic sectional view of the microelectromechanical transducer element 100 from Fig. 1.

[0058] The figures a) and b) show the microelectromechanical transducer element 100 from Fig. 1 in a sectional view along the x-axis in Fig. 1. In Fig. 2 shows only a portion of the transducer element 100. In particular, a portion of one of the frame elements 115 and the anchoring portion 127 of the first electrode 103 formed thereon, a portion of one of the spring elements 119, and a portion of the movable element 117 with two second electrode elements 131 of the second electrode 105 formed thereon are shown.

[0059] In graphics a) and b), it can be seen that the anchoring section 127 of the first electrode 103 is fixed to the frame element 115. The connecting section 129 of the first electrode 103, however, is arranged freely suspended in the connecting region 141 of the receiving space 109 in the region of the spring element 119. Furthermore, the comb elements 143 of the first electrode 103 shown in graphics a) and b) in the electrode section 125 are also arranged freely suspended in the electrode region 137 of the receiving space 109.

[0060] In contrast, the two illustrated second electrode elements 131 of the second electrode 103 are arranged fixedly with the movable element 117.

[0061] Furthermore, it can be seen that the further boundary layer 149 is formed directly on the frame element 115, the spring element 119, and the movable element 117. The anchoring section 127 of the first electrode 103 and the shown second electrode elements 131 of the second electrode 105 are arranged directly on the further boundary layer 149.

[0062] The boundary layer 123 is arranged opposite the further boundary layer 149. The support element 121 is formed between the two boundary layers 123. The receiving space 109 is thus spanned by the two boundary layers 123, 149 and the support element 121. Fig. 2, the support element 121 is shown only in pieces in order to allow a view into the receiving space 109.

[0063] In the embodiment shown, the second electrode elements 131 serve as additional support elements. For this purpose, the second electrode elements 131 contact the boundary layer 123 as well as the further boundary layer 149.

[0064] In graphic b), relative to graphic a), a movement of the movable element 117 and the spring element 119 relative to the rigid frame element 115 along a direction of movement 147 is shown. The movement of the movable element 117 and the spring element 119 also causes the electrode region 137 and the connecting region 141 of the receiving space 109 to move along with the movable element 117 and the spring element 119. Due to the fixed design of the second electrode elements 131 on the movable element 117, the second electrode elements are also moved along with the movable element 117 and the electrode region 137 of the receiving space 109. The connecting section 129 of the first electrode 103, which is freely suspended in the connecting region 141 of the receiving space 109, is, in contrast, moved in the opposite direction to the direction of movement 147 relative to the connecting region 141.At the same time, the comb elements 143 of the first electrode 103, which are arranged freely suspended in the electrode region 137, are moved relative to the electrode region 137 of the receiving space 109 and relative to the second electrode elements 131. The movement of the movable element 117 relative to the rigid frame element 115 thus results in a relative movement of the first electrode 103 to the second electrode 105.

[0065] According to one embodiment, the microelectromechanical transducer element 100 is designed as an actuator element. This means that by controlling the first and second electrodes 103, 105, a movement of the movable element 117 relative to the rigid frame element 115 is effected. This can achieve a movement of the movable element 117 relative to the rigid frame elements 115 along the x-direction of the Fig. 1 shown coordinate system.

[0066] Fig. 3 shows a further schematic sectional view of the microelectromechanical transducer element 100 according to a further embodiment.

[0067] The embodiment in Fig. 3 is based on the embodiment in Fig. 2 and includes all features described therein. Should these remain unchanged in the embodiment shown, a detailed description will be omitted.

[0068] In the embodiment shown, the second electrode elements 131 of the second electrode 105 do not serve as support elements 121 of the capsule structure 109. The second electrode elements 131 are formed exclusively on the further boundary layer 149.

[0069] In the embodiment shown, the microelectromechanical transducer element 100 further comprises a third electrode 133. In the embodiment shown, the third electrode 133 is arranged as a further movable electrode on the movable element 117, analogous to the second electrode 105. Analogous to the second electrode elements 131, the third electrode 133 is arranged directly on the further boundary layer 149.

[0070] The comb elements 143 of the electrode section 125 of the first electrode 103 are arranged in the electrode region 137 in the z-direction above the second and third electrodes 105, 133. Bidirectional operation of the transducer element 100 can be achieved by the third electrode 133.

[0071] By controlling the third electrode 133, a movement of the movable element 117 relative to the rigid frame element 115 can be achieved in a direction opposite to a second direction of movement oriented relative to the direction of movement 147. The two directions of movement are oriented parallel but point in opposite directions.

[0072] Fig. 4 shows a schematic representation of a microelectromechanical component 200 with a microelectromechanical transducer element 100. According to one embodiment, the microelectromechanical component 200 can be designed as a loudspeaker.

Claims

[1] Microelectromechanical transducer element (100) with an electrode system (101), with at least a first electrode (103), a second electrode (105) and a capsule structure (107), wherein the electrode system (101) is arranged in a receiving space (109) defined by the capsule structure (107), wherein the second electrode (105) is mounted in the receiving space (109) so as to be movable relative to the first electrode (103), and wherein the capsule structure (107) effects a fluid-tight encapsulation of the electrode system (101) from an external environment (111) of the transducer element (100). [2] The transducer element (100) of claim 1, further comprising a base structure (113) having a rigid frame element (115) and a movable element (117), wherein the movable element (117) is resiliently movable relative to the rigid frame element (115), and wherein the first electrode (103) is fixed to the rigid frame element (115) and the second electrode (105) is fixed to the movable element (117). [3] Transducer element (100) according to claim 2, wherein the base structure (113) further comprises at least one spring element, and wherein the movable element (117) is resiliently connected to the rigid frame element (115) via the at least one spring element (119). [4] Transducer element (100) according to claim 2 or 3, wherein the capsule structure (107) comprises at least one support element (121) and at least one elastically deformable boundary layer (123, 149), wherein the at least one support element (121) is formed on the base structure (113), and wherein the receiving space (109) is spanned over the base structure (113), the at least one support element (121) and the boundary layer (123, 149). [5] Transducer element (100) according to one of the preceding claims 2 to 4, wherein the receiving space (109) is at least partially fixedly connected to the movable element (117), and wherein the receiving space (109) is moved along with a movement of the movable element (117) relative to the rigid frame element (115). [6] Transducer element (100) according to one of the preceding claims 2 to 5, wherein the first electrode (103) comprises an electrode section (125), an anchoring section (127) and a connecting section (129) connecting the electrode section (125) to the anchoring section (127), wherein the anchoring section (127) is anchored to the rigid frame element (115), and wherein the electrode section (125) is arranged opposite the second electrode (105) in a region of the movable element (117). [7] Transducer element (100) according to one of the preceding claims 2 to 6, wherein the second electrode (105) comprises a plurality of second electrode elements (131) formed on the movable element (117). [8] Converter element (100) according to one of the preceding claims, wherein the receiving space (109) is filled with a gas mixture. [9] Transducer element (100) according to claim 8, wherein a gas pressure of the gas mixture within the receiving space (109) is lower than an atmospheric pressure of the external environment (111) of the transducer element (100). [10] Transducer element (100) according to one of the preceding claims, wherein the electrode system (101) further comprises a third electrode (133). [11] Transducer element (100) according to claim 10, wherein the third electrode (133) is formed on the movable element (117) or on the rigid frame element (115). [12] Converter element (100) according to one of the preceding claims, wherein at least one electrode (103, 105, 133) of the electrode system (101) forms at least one support element (121) of the capsule structure (107). [13] Converter element (100) according to one of the preceding claims, wherein the electrodes (103, 105, 107) of the electrode system (101) are designed as comb electrodes, stray field electrodes or as NED electrodes. [14] Transducer element (100) according to one of the preceding claims, wherein the transducer element (100) is designed as an actuator element for driving a movement. [15] Microelectromechanical component (200) with at least one transducer element (100) according to one of the preceding claims 1 to 14.

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