152 comprises at least a second electrode 154. The first electrodes 134 are arranged flat next to one another in a first electrode plane 135. The second electrode 154 is arranged flat in a second electrode plane 155. The first electrode plane 135 and the second electrode plane 155 are substantially parallel. A movement of the second electrode structure 152 relative to the first electrode structure 132 in a direction of movement parallel to the electrode planes 135, 155 can be triggered by applying voltages to the electrodes 134, 154.

The movement of the second electrode structure 152 relative to the first electrode structure 132 can in particular include a movement of the second substrate 151 including the second electrodes 152 in the first extension direction 101. Optionally, a functional element 112 can be arranged on the second substrate 151. The microelectromechanical actuator structure 100 can be configured to drive the functional element 112.

In particular, a first pn junction 133 can be formed between each of the first electrodes 134 and the first substrate 131, as optionally shown in FIG. 1. Because a first pn junction 133 is formed between the first electrodes 134 and the first substrate 131, a dielectric between the first electrodes 134 and the first substrate 131 can be dispensed with. In particular, voltages can be applied to the first electrodes 134 and/or to the first substrate 131 such that the first pn junction 133 or the first pn junctions 133 are blocking, and thus an additional insulating layer can be dispensed with, i.e., the dielectric is not required.

Because a second pn junction 153 is formed between the second electrode 154 and the second substrate 151, a dielectric between the second electrode 154 and the second substrate 151 can also be dispensed with. In particular, voltages can be applied to the second electrode 154 and/or to the second substrate 151 such that the second pn junction 153 is blocking and thus an additional insulating layer can be dispensed with, i.e., the dielectric is not required.

The fact that the electrode planes 135, 155 are substantially parallel can mean that an angle between the first electrode plane 135 and the second electrode plane 155 is a maximum of five degrees, in particular a maximum of two degrees and preferably a maximum of 0.5 degrees. The electrode planes 135, 155 can also be aligned exactly in parallel with one another, as shown by way of example in FIG. 1.

An electrode gap between the first electrodes 134 and the second electrode 154 in a direction perpendicular to the first electrode plane 135 and/or perpendicular to the second electrode plane 155 can be a maximum of 3 micrometers. The electrode gap can be defined in the second extension direction 102, for example perpendicular to the movement in the first extension direction. The electrode gap may depend on the intended use of the microelectromechanical actuator structure 100. The electrode gap can be in the range of 0.1 micrometer, i.e., 100 nanometers, to 1.5 micrometers. For use in a loudspeaker, the upper part of this range, for example between 1 micrometer and 1.5 micrometers, can be provided, while other applications can better be provided in the lower part of this range.

The first substrate 131 and the first electrodes 134 can consist of a semiconductor material, wherein the first substrate 131 and the first electrodes 134 are doped inversely to one another. The second substrate 151 and the second electrodes 154 can consist of a semiconductor material, in particular the same semiconductor material, wherein the second substrate 151 and the second electrodes 154 are also doped inversely to one another.

This results in a simple construction of the microelectromechanical actuator structure 100. The electrodes 134, 154 can be produced in particular by means of the introduction of local doping.

The semiconductor material can be silicon. The locally introduced doping creates a change in conductivity in the semiconductor material/silicon in some regions. In some regions means both laterally parallel to the electrode planes 135, 155, and variable in depth. Parallel to the electrode planes 135, 155 can mean in the first extension direction 101 and in the third extension direction 103, while the depth is defined in the second extension direction 102. This can be achieved laterally via mask technology and in depth also via a suitable selection of doping elements, via ion energy when using implantation technology, via outdiffusion under temperature treatment or via additional semiconductor material layer deposition. The change in conductivity of the semiconductor material refers, in addition to the conductivity itself (in the sense of ohmic specific conductivity), in particular to the variation and differentiation of the semiconductor type. N-type and p-type semiconductor materials differ by the majority charge carriers responsible for the conductivity, wherein in the n-type the electron concentration determines the conductivity and in the p-type the hole concentration determines it. In addition to the electrodes that form structures for planar displacement capacitor structures, their potential supply lines can also be generated analogously, wherein the characteristics of pn junctions are also utilized for the potential supply lines. By appropriately triggering the potential of the sub-regions of the actuator structure, the pn junctions are used for the functionality either conductively in the forward direction (potential conduction) or blockingly in the reverse direction (potential isolation).

If silicon is provided as the semiconductor material, arsenic, phosphorus or antimony can be used as donors for the n-doping and boron, aluminum or indium can be used for the p-doping.

The first substrate 131 can be adjacent to the first electrode structure 132, as shown in FIG. 1. The second substrate 151 may alternatively or additionally adjoin the second electrode structure 152, as also shown in FIG. 1.

The microelectromechanical actuator structure 100 shown in FIG. 1 can in particular be controlled in such a way that a direct voltage is applied to the first electrodes 134, wherein one of the first electrodes 134 is at a positive potential and a first electrode 134 arranged next to it is at a negative potential.

The second electrode 154 is supplied with an alternating voltage or a variable/controllable direct voltage, wherein a potential of the second electrode 154 defines a deflection of the second drive unit 150. Furthermore, also applying a potential to the chip frame 111 can be provided.

In the following, exemplary embodiments of the present invention are described, which can each optionally be provided individually or in combination for the microelectromechanical actuator structure 100 of FIG. 1.

In one exemplary embodiment of the microelectromechanical actuator structure 100, the first drive unit 130 is immobile relative to the chip frame 111, as shown in FIG. 1. The second drive unit 150 is joined to the chip frame 111 by means of spring elements 113. Thus, the second drive unit 150 moves while the first drive unit 130 remains stationary.

In one exemplary embodiment of the microelectromechanical actuator structure 100, the first substrate 131 has a p-doping. The first doping is therefore a p-doping. The first electrode structure 132 has an n-doping. The first inverse doping is therefore an n-doping. The second substrate 151 has a p-doping. The second doping is therefore a p-doping. The second electrode structure 152 has an n-doping. The second inverse doping is therefore an n-doping.

In one exemplary embodiment of the microelectromechanical actuator structure 100, the first substrate 131 has an n-doping. The first doping is therefore an n-doping. The first electrode structure 132 has a p-doping. The first inverse doping is therefore a p-doping. The second substrate 151 has an n-doping. The second doping is therefore an n-doping. The second electrode structure 152 has a p-doping. The second inverse doping is therefore a p-doping.

In one exemplary embodiment of the microelectromechanical actuator structure 100, the first substrate 131 has a p-doping. The first doping is therefore a p-doping. The first electrode structure 132 has an n-doping. The first inverse doping is therefore an n-doping. The second substrate 151 has an n-doping. The second doping is therefore an n-doping. The second electrode structure 152 has a p-doping. The second inverse doping is therefore a p-doping.

In one exemplary embodiment of the microelectromechanical actuator structure 100, the first substrate 131 has an n-doping. The first doping is therefore an n-doping. The first electrode structure 132 has a p-doping. The first inverse doping is therefore a p-doping. The second substrate 151 has a p-doping. The second doping is therefore a p-doping. The second electrode structure 152 has an n-doping. The second inverse doping is therefore an n-doping.

In one exemplary embodiment of the microelectromechanical actuator structure 100, the first substrate 131 has a doping concentration of 1*10{circumflex over ( )}18 or less, preferably 1*10{circumflex over ( )}17 or less and in particular 1*10{circumflex over ( )}16 or less doping atoms per cubic centimeter.

In one exemplary embodiment of the microelectromechanical actuator structure 100, the second substrate 151 has a doping concentration of 1*10{circumflex over ( )}18 or less, preferably 1*10{circumflex over ( )}17 or less and in particular 1*10{circumflex over ( )}16 or less doping atoms per cubic centimeter.

In one exemplary embodiment of the microelectromechanical actuator structure 100, the first electrode structure 132 has a doping concentration of 5*10{circumflex over ( )}18 or more, preferably 5*10{circumflex over ( )}19 or more and in particular 5*10{circumflex over ( )}20 or more doping atoms per cubic centimeter.

In one exemplary embodiment of the microelectromechanical actuator structure 100, the second electrode structure 152 has a doping concentration of 5*10{circumflex over ( )}18 or more, preferably 5*10{circumflex over ( )}19 or more and in particular 5*10{circumflex over ( )}20 or more doping atoms per cubic centimeter.

A space charge zone is formed at the first pn junctions 133 and at the second pn junction 153, respectively. The space charge zone extends at both sides, i.e., into the electrode structures 132, 152 and also into the substrates 131, 151. The width of the two space charge zone regions is determined by the respective doping concentrations of electrode structures 132, 152 and substrates 131, 151. By appropriately triggering the electrical potential, this pn junction blocks, so that different potentials can be set in regions having different doping with low losses. Low loss can mean that only a small blocking saturation current flows across the pn junction (due to thermally generated minority charge carriers in the respective n- and p-doped regions), thereby achieving a low power loss to maintain the potential differences. This property can be called insulation of the pn junction.

If, for example, the first substrate 131 is p-doped and the first electrode structure 132 is n-doped and a direct voltage of +30 volts or −30 volts is to be applied to the first electrodes 134, the first substrate 131 can be subjected to a potential of less than −30 volts, i.e., in particular a negative direct voltage with a magnitude of more than 30 volts, so that all the first pn junctions 133 are blocking. If, for example, the second substrate 151 is p-doped and the second electrode structure 152 is n-doped and a DC voltage that is variable within a range is to be applied to the second electrode, the second substrate 151 can in particular be subjected to a potential smaller than the smallest possible DC voltage so that the second pn junctions 153 are also blocking. If the second electrode 154 is to be subjected to an alternating voltage, the potential applied to the second substrate 151 can be greater in magnitude than an amplitude of the alternating voltage and can be negative so that the second pn junctions 153 are also blocking. If the doping is reversed, a potential greater than the maximum possible voltage applied to the electrodes 134, 154 can be applied to the substrates 131, 151 analogously so that the pn junctions 133, 153 are blocking.

FIG. 2 shows a cross section of a microelectromechanical actuator structure 100, which corresponds to the microelectromechanical actuator structure 100 of FIG. 1, unless differences are described below.

More than one second electrode 154 is arranged in the second electrode structure 152. All second electrodes 154 are located in the second electrode plane 155. In this case, all second electrodes 154 have the doping inverse to the second substrate 151 and thus a second pn junction 153 is arranged between all second electrodes 154 and the second substrate 151.

In one exemplary embodiment of the microelectromechanical actuator structure 100, the first drive unit 130 comprises a further first substrate 136. The further first substrate 136 is doped inversely to the first substrate 131. The further first substrate 136 adjoins the first substrate 131, so that the first electrodes 134, the first substrate 131 and the further first substrate 136 each form an npn or a pnp layer sequence (corresponding to a transistor structure). In this case, the further first substrate 136 can be provided with a potential independently of the first substrate 131, so that a potential difference can be provided between the chip frame 111 and the first substrate 131. This embodiment shown in FIG. 2 can also be provided in the microelectromechanical actuator structure 100 of FIG. 1.

In one exemplary embodiment of the microelectromechanical actuator structure 100, the second drive unit 150 comprises a further second substrate 156. The further second substrate 156 is doped inversely to the second substrate 151. The further second substrate 156 adjoins the second substrate 151, so that the second electrodes 154, the second substrate 151 and the further second substrate 156 each form an npn or a pnp layer sequence (corresponding to a transistor structure). In this case, the further second substrate 156 can be provided with a potential independently of the second substrate 151, so that a potential difference can be provided between the chip frame 111 and the second substrate 151. This embodiment shown in FIG. 2 can also be provided in the microelectromechanical actuator structure 100 of FIG. 1.

In one exemplary embodiment of the microelectromechanical actuator structure, the first substrate 131 and the further first substrate 136 each form a layer of the first drive unit 130. In one exemplary embodiment, the second substrate 151 and the further second substrate 156 each form a layer of the second drive unit 150. This is also shown in FIG. 2.

With the exemplary embodiment of the microelectromechanical actuator structure shown in FIG. 2, an advantageous triggering of the electrodes 134, 154 is possible due to the pnp or npn layer structures present in both drive units 130, 150, which can act as pnp or npn transistor structures. In particular, the further first substrate 136 or the further second substrate 156 in this embodiment can each be placed at a potential identical to that of the chip frame without influencing the blocking pn junctions 133, 153.

FIG. 3 shows a cross section of a microelectromechanical actuator structure 100, which corresponds to the microelectromechanical actuator structure 100 of FIG. 2, unless differences are described below. In particular, the second drive unit 150 comprises more than one second electrode 154. The first drive unit 130 comprises the further first substrate 136, the second drive unit 150 comprises the further second substrate 156. In this exemplary embodiment, the further substrates 136, 156 are not designed as a layer, but as a doping well. Such a configuration is also possible in the exemplary embodiments of FIGS. 1 and 2. In the exemplary embodiment of FIG. 3, the design of the further substrates 136, 156 can alternatively be provided as layers analogous to FIG. 2.

In one exemplary embodiment of the microelectromechanical actuator structure 100, as optionally shown in FIG. 3, at least one trench 137 is arranged between the first electrodes 134. In FIG. 3, trenches 137 are shown between all first electrodes 134. A trench width here can be in the order of magnitude of the electrode gap. In particular, the trench width can be a maximum of 2 micrometers or preferably a maximum of 1 micrometer. The trench width can extend in parallel with the electrode planes 135, 155, i.e., in the first extension direction 101. A trench depth can be a maximum of 6 micrometers or in particular a maximum of 3 micrometers or preferably a maximum of 1 micrometer. The trench depth can be defined in particular in the second extension direction 102. It can be provided that such a trench 137 is not arranged between all of the first electrodes 134, but only between some of the first electrodes 134. However, the trench 137 can also be arranged between all of the first electrodes 134. By means of the trenches 137, it is possible to keep a spacing of the first electrodes 134 small, in particular in the first extension direction 101. If semiconductor material were arranged there instead of the trenches 137, a space charge zone could form therein, which could lead to undesired contact between the first electrodes 134 and thus to a functional impairment. This can be prevented or at least avoided by the trenches.

Such a trench may also be arranged between the second electrodes 154 if more than one second electrode 154 is provided. This trench can also have the properties already described. Such trenches are not shown in FIG. 3, because an alternative embodiment is to be described in FIG. 3 with respect to the second drive unit 150.

In one exemplary embodiment of the microelectromechanical actuator structure 100, the second electrode structure 152 comprises more than one second electrode 154, as also shown in FIG. 3. An intermediate recess 157 is arranged between the second electrodes 154. Instead of the intermediate recess 157, a substrate region without second electrodes 154 can also be provided. A width of the intermediate recess 157 or of the substrate region is greater than a width of the second electrodes 154, in particular as relates to the second extension direction 102. A depth of the intermediate recess 157 or of the substrate region is deeper than the second electrodes 154, in particular as relates to the second extension direction 102. The depth of the intermediate recess 157 or of the substrate region can in particular be a multiple of the electrode gap. In particular, the depth of the intermediate recess 157 or the substrate region can be up to 10 times the electrode gap or correspond to the already described depth of the trenches 137.

The trenches 137 explained in connection with FIG. 3 can also be provided in the embodiments of FIGS. 1 and 2. The intermediate recesses 157 explained in connection with FIG. 3 can also be provided in the embodiments of FIG. 2.

The electrodes 134, 154, substrates 131, 151 and further substrates 136, 156 shown in FIGS. 1 to 3 can be contacted in particular by means of doped semiconductor structures in order to be able to apply the voltages and potentials described above. The contacting of the second drive unit 150 can be carried out in particular via the spring elements 113.

FIG. 4 shows a cross section of a detail of a further microelectromechanical actuator structure 100. The first electrode structure 132 comprises a gate electrode 138. A deflection of the drive structure 120 can be determined by means of the gate electrode 138. For this purpose, the second electrode structure 152, as also shown in FIG. 4, can comprise a first detection electrode 158 and a second detection electrode 159. The gate electrode 138 overlaps the first detection electrode 158 at least partially.

Furthermore, an inversion channel