Sensor having a membrane electrode, a counter electrode, and at least one spring

Abstract

A sensor is disclosed, which has a membrane electrode, a counter electrode, and at least one spring. In particular, the sensor according to the example may include: a structure (12); a membrane electrode (14) which is deformable as a result of being subjected to pressure and is in contact with the structure (12); a counter electrode (16) which is mechanically connected to the structure (12) and is separated from the membrane electrode (14) by a gap (18); and at least one spring (20) which is mechanically connected to the membrane electrode (14) and the counter electrode (16) so as to apply an elastic force between the membrane electrode (14) and the counter electrode (16).

Description

Technical Field

[0001] The present document relates to a sensor (eg a pressure sensor and / or an acoustic sensor, eg for a microphone) having a membrane electrode, a counter electrode and at least one spring inserted between the membrane electrode and the counter electrode.

[0002] This document also relates to methods for manufacturing a sensor, such as the one described above. Background Art

[0003] A pressure sensor (such as an acoustic sensor) may include at least two electrodes (e.g., at least one membrane electrode and at least one counter electrode). For example, the membrane electrode may be deformable as a result of being subjected to pressure (e.g., pressure caused by sound). The counter electrode may be non-deformable, and the counter electrode may be fixed to a fixed structure. The membrane electrode may be connected to a fixed structure of the sensor corresponding to an edge of the membrane.

[0004] The membrane electrode may be manufactured to have tensile stress, for example to counteract attractive electrostatic forces between the membrane electrode and the counter electrode.

[0005] By virtue of the deformation due to pressure, a high concentration of stress can be localized corresponding to the membrane edge. As a result, the robustness of the sensor is reduced overall.

[0006] Due to the assembly process, thermal expansion of different packaging materials and aging of the material packaging, additional stresses occur between the membrane electrode and the counter electrode. Such additional stresses change the flexibility of the membrane, thereby reducing the sensitivity, for example. This causes significant yield losses.

[0007] Because the edges of the membrane electrode are fixed to the structure, large-area movement of the membrane is restricted. Therefore, the overall signal amplitude is reduced. Therefore, the chip delivers a limited signal and / or the signal-to-noise ratio (SNR) is reduced. Overall, the sensor needs to be designed to be larger than necessary, thus increasing the cost of achieving satisfactory signal and SNR values.

[0008] Furthermore, tolerances during manufacturing result in the membrane electrodes having an imperfect positioning. Therefore, a calibration usually needs to be performed to adapt the specific position of the membrane relative to the structure. Therefore, without calibration, it is difficult to achieve the result that different sensors (nominally identical) operate with exactly the same sensitivity. However, calibration implies complication of software and hardware.

[0009] Furthermore, the stress on the membrane also depends on the external temperature. Therefore, it is difficult to realize a sensor that can function in all climatic conditions.

[0010] Limited mechanical robustness may cause field failures and require additional measures, restrictions and costs. Therefore thicker membranes need to be used.

[0011] Therefore, this paper aims to find out techniques to at least partially reduce the above mentioned drawbacks. Summary of the invention

[0012] According to one example, a sensor is provided, comprising: a structure; a membrane electrode, which is deformable as a result of being subjected to pressure and which is in contact with the structure; a counter electrode, which is mechanically connected to the structure and is separated from the membrane electrode by a gap; and at least one spring, which is between the membrane electrode and the counter electrode so as to apply an elastic force between the membrane electrode and the counter electrode.

[0013] According to an aspect, the sensor may include a flexible membrane connector connecting the membrane electrode to the structure.

[0014] According to one example, a method is provided for manufacturing a semiconductor pressure sensor and / or an acoustic sensor, the method comprising:

[0015] preparing a first element on a substrate, wherein the first element is selected between a membrane electrode and a counter electrode;

[0016] preparing at least one spring element, the at least one spring element being adjacent to the first element;

[0017] The second element is prepared so that at least one spring element is adjacent to the second element and so that the at least one spring element is elastically connected to the first element and the second element, wherein the second element is a counter electrode or a membrane electrode, and wherein the second element is an element selected between the counter electrode and the membrane electrode and not selected for the first element. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 , Figure 2 A sensor according to an example is shown.

[0019] Figure 3 Elements according to examples are shown.

[0020] Figure 4 and Figure 5 A sensor according to an example is shown.

[0021] Figures 6 to 9 Elements according to examples are shown.

[0022] Figures 10 to 17 Intermediate steps according to the method are shown.

[0023] Fig.18A sensor according to an example is shown.

[0024] Fig.19 Intermediate steps according to the method are shown. DETAILED DESCRIPTION

[0025] Figure 1 A sensor 10 according to an example is shown. The sensor 10 may be a pressure sensor. The pressure sensor 10 may be an acoustic sensor (e.g., for a microphone) or a pressure sensor (e.g., for measuring external pressure, such as atmospheric pressure). The sensor 10 may be a semiconductor device. The sensor 10 may be a microelectromechanical system (MEMS). The sensor 10 may be an embedded device. The sensor 10 may be an on-chip device. The sensor 10 may be a package, or the sensor 10 may be enclosed in a package. The sensor 10 may include a structure 12. The structure 12 may be fixed. The structure 12 may include (or be included in) a chip and / or a package.

[0026] The sensor 10 can be operated as a capacitor having two electrodes at a variable distance (gap) and thus having a variable capacitance. The capacitance can vary depending on the distance between the electrodes. In general, the greater the distance, the smaller the capacitance and vice versa. In general, it means an inverse ratio between the distance between the electrodes and the capacitance.

[0027] The sensor 10 may include a membrane electrode 14 (e.g., a conductive material). The membrane electrode 14 may be flexible (e.g., a flexible and / or elastic material). The membrane electrode 14 may be deformed as a result of being subjected to pressure (e.g., pressure vibrations, such as sound). The membrane electrode 14 may be in contact with the structure 12. For example, the membrane electrode 14 may be cantilevered and connected to the structure 12. The membrane electrode 14 may be non-rigidly fixed to the structure 12 (e.g., a stress-free membrane). The membrane electrode 14 may be suspended (e.g., by a spring or other elastic element, such as a flexible membrane connector). The membrane electrode 14 may have a first surface 14a (which may be an exposed surface) and a second surface 14d (which may be a non-exposed surface).

[0028] The sensor 10 may include a counter electrode 16 (e.g., a conductive material). The counter electrode 16 may be a rigid material. The counter electrode 16 may be a back plate. The counter electrode 16 may be mechanically connected to the structure 12 (e.g., fixed to the structure 12 and / or suspended by the structure 12). The counter electrode 16 may have a first surface 16b (which may be a non-exposed surface) and a second surface 16d (which may be an exposed surface).

[0029] The counter electrode 16 may be understood to operate with the membrane electrode 14 to form a capacitor. The counter electrode 16 may be separated from the membrane electrode 14 by a gap 18.

[0030] The counter electrode 16 may include an aperture 16c. The aperture 16c may, among other things, allow fluid communication through the counter electrode 16 between the outside of the membrane electrode 14 and the at least one surface 14a.

[0031] The counter electrode 16 together with the membrane electrode 14 can be operated as a capacitor with variable capacitance. The gap 18 can be an air gap (other fluids can be used in different environments; for example, in an underwater environment, the gap 18 can be filled with water). The gap 18 can be operated as a dielectric in the capacitor, which in this case is variable. The capacitor obtained has a variable capacitance based on the variable gap 18, which in turn can be varied, for example, based on pressure. The capacitor with variable capacitance can also be used as an audio / acoustic / sound sensor (for example, operated as a microphone): for example, acoustic vibrations can be measured based on the modification of the gap 18.

[0032] The sensor 10 can be configured in the thickness direction (in Figure 1 vertical) and a horizontal plane extending perpendicular to the thickness direction (in Figure 1 The sensor 10 may extend more in the horizontal plane than in the thickness direction. The membrane electrode 14 and the counter electrode 16 may extend primarily in a planar manner (e.g., in the horizontal plane). The gap 18 may have a volume that primarily extends horizontally, but the height of the gap 18 may vary at least in the thickness direction. The deformation of the membrane electrode 14 may be considered as a deformation in the thickness direction, for example: the height of the gap 18 is reduced and / or increased in the thickness direction depending on the pressure (and the capacitance of the capacitor is changed accordingly). As can be seen in the thickness direction, the membrane electrode 14 and the counter electrode 16 may at least partially overlap each other.

[0033] The membrane electrode 14 may have a surface 14a, which may face the surface 16b of the counter electrode 16, and the surface 14a and the surface 16b are separated by a gap 18. The surface 16b may be an inner (non-exposed) surface. Figure 1 In the embodiment, the membrane electrode 14 is located further inside than the counter electrode 16, but in other examples, the relative positions of the surfaces of the membrane electrode 14 and the counter electrode 16 may be reversed.

[0034] It has been noted that the presence of at least one spring 20 inserted between the membrane electrode 14 and the counter electrode 16 (e.g., in the gap 18) is beneficial for the sensor 10. The at least one spring 20 may be mechanically connected to both the membrane electrode 14 and the counter electrode 16. The at least one spring 20 may at least partially support the membrane electrode 14. The at least one spring 20 and the membrane electrode 14 may be fixed and / or adhered to each other. The at least one spring 20 may at least partially support the membrane electrode 14. The at least one spring 20 and the membrane electrode 14 may be fixed and / or adhered to each other. In some cases, the counter electrode 16 may at least partially support the membrane electrode 14 by the at least one spring 20. The at least one spring 20 may be an elastic member that applies an elastic force between the membrane electrode 14 and the counter electrode 16. In particular, by using at least one spring 20, tensile stresses at the edges of the membrane electrode 14 may be reduced or avoided.

[0035] For example, the structure 12 may include a substrate 24, which may include a backside etch layer 25. The structure 12 may include a capping portion 26 (e.g., a capping oxide such as TEOS, tetraethyl orthosilicate). Between the capping portion 26 and the substrate 24, a stop layer 28 (e.g., a stop layer of a stop oxide material) may be disposed in some areas of the substrate 24.

[0036] As from Figure 1 As can be seen, the structure 12 may include a membrane electrode terminal 32, which is electrically connected to the membrane electrode 14 (e.g., through a conductive connection obtained in a conductive hole). The structure 12 may include a counter electrode terminal 31, which is electrically connected to the counter electrode 16 (e.g., through another conductive connection obtained in the conductive hole). The terminals 31 and 32 may be electrically connected to internal or external circuits, and / or external devices and other components (e.g., through terminal paths and / or through external pads). The passivation layer 33 may be arranged to contact between the metal layers forming the terminals 31 and / or 32 and / or the covering portion 26.

[0037] At least one spring 20 may include a membrane side foot 20a and / or a counter electrode side foot 20b, the membrane side foot 20a being adjacent to the membrane electrode 14 (e.g., adjacent to the surface 14a), and the counter electrode side foot 20b being adjacent to the counter electrode 16 (e.g., adjacent to the surface 16b). At least one of the feet 20a and 20b may be fixed and / or adhered to the corresponding membrane electrode 14 or counter electrode 16. The main portion 20c of the spring 20 may be mechanically connected between the membrane side foot 20a and the counter electrode side foot 20b.

[0038] In an example, a plurality of springs 20 may be placed between the membrane electrode 14 and the counter electrode 16. In an example, a plurality of springs 20 are arranged in an array and / or matrix (e.g., at regular distances from each other). In an example, a plurality of springs 20 are arranged so as to have the same spring constant, or to have a spring constant that varies by a maximum of 1% or 5% between different springs 20. The main portion 20c may provide elasticity. The main portion 20c of the spring 20 may extend generally in an inclined direction. Different springs 20 may have the same or similar inclination angle within a tolerance range of 1% or 5%. The inclination may provide elasticity. The inclination may affect the spring constant. The length of the main portion 20c of the spring 20 is generally less important than the inclination.

[0039] A flexible membrane connector 22 may be provided to mechanically connect (e.g., support and / or hold and / or fix) the membrane electrode 14 to the structure 12. The flexible membrane connector 22 may be elastically deformed (e.g., in the thickness direction) at least in part as a result of the deflection (e.g., by pressure) of the membrane electrode 14. The flexible membrane connector 22 may include a transverse spring. The flexible membrane connector 22 may allow electrical conduction. The flexible membrane connector 22 may be obtained from the same material as the membrane electrode 14. The flexible membrane connector 22 may be obtained by modifying (e.g., by cutting or punching) a portion of the membrane electrode 14.

[0040] If Figure 2 As shown, in operation, the membrane electrode 14 can be deformed between a first position (a gap 18 of a first height in the thickness direction as a result of being subjected to a first pressure) and a second position (a gap 18 of a second height in the thickness direction as a result of being subjected to a second pressure) to change between a first capacitance and a second capacitance. For example, as a result of being subjected to corresponding multiple pressures, multiple other positions (e.g., intermediate positions) can be obtained and cause multiple corresponding capacitances. As shown from Figure 2 It can be seen that also by virtue of the use of at least one spring 20 and / or through its combined effect with the elastic deformation of the flexible membrane connection 22, a more uniform deflection (uniform membrane deflection) is achieved, wherein the gap 18 tends to be uniform along the horizontal plane.

[0041] Figure 3 The direction perpendicular to the thickness direction ( Figure 3 (a) in the horizontal plane) and the direction perpendicular to the horizontal plane ( Figure 3 (b) in the figure shows an example of the membrane electrode 14. It should be noted that Figure 3 Part (a) of Fig.10 , and refers to the Figure 1 Instead, Figure 3Part (b) in FIG. 1 refers to the final configuration of the membrane electrode 14 .

[0042] The membrane electrode 14 may include a main portion 14', the main portion 14' providing the surface 14a, and / or the main portion 14' being used as an electrode of a capacitor. The flexible membrane connector 22 may be obtained by a cutout or hole 22d in the membrane electrode 14 (e.g., an arcuate portion, e.g., concentric with the edge 14r of the membrane electrode 14), the cutout or hole 22d corresponding, for example, to a portion 22b of the membrane electrode 14, which is in contact with the structure 12 (e.g., the portion 22b may be sandwiched in the structure 12, e.g., between the cover portion 26 and the substrate 24 or the stop layer 28 of the substrate 24; the portion 22b may be cantilevered to the structure 12). The cutout or hole 22d may be closer to the edge 14r of the membrane electrode 14 than to the center of the membrane electrode 14. The cutout or hole 22d may be closer to the portion 22b of the membrane electrode 14 than to the center of the membrane electrode 14. In this example, the cutout or hole 22d forming the flexible membrane connector 22 is arcuate (e.g., arched), and / or the cutout or hole 22d forming the flexible membrane connector 22 is concentrically cut to the periphery of the main portion of the membrane electrode 14. The cutout or hole 22d may be a through cutout or through hole, and the cutout or hole 22d may pass through the entire thickness of the membrane electrode in the thickness direction.

[0043] When the membrane electrode 14 is deformed (e.g., by pressure), the flexible membrane connector 22 may deform accordingly: for example, a cutout or hole 22d in the membrane electrode 14 may allow the main portion 14' to move more evenly relative to the portion 22b, thereby allowing the main portion 14' to move more evenly along the horizontal plane in the gap 18 (see Figure 2 ) to maintain a generally uniform height.

[0044] The stop layer 28 may be disposed between the membrane electrode 14 (and / or the membrane connector 22 ) and the substrate 24 .

[0045] exist Figure 1 In the example of , the membrane electrode 14 is cantilevered to the structure 12. At least one spring 20 (for example, in combination with a flexible membrane connector 22) can allow the height of the gap 18 to be kept uniform in the horizontal plane. Figure 1 and Figure 3 It can be seen that part 22b of membrane electrode 14 may be directly connected to and / or in contact with structure 12, whereas most or all of edge 14r of membrane electrode 14 is not mechanically connected to structure 22. At least one spring 20 may still be in contact with both membrane electrode 14 and counter electrode 16.

[0046] Figure 3 An example of may allow for horizontal (e.g., Figure 2from right to left in the middle) and in the thickness direction (e.g. Figure 2 The effective electrical connection is achieved. Figure 3 It can be seen that the cutout or hole 22d may be a partial cutout or hole, and thus the membrane electrode 14 may find an electrical path towards the membrane electrode terminal 32 (eg by being connected to the portion 22b of the structure 12).

[0047] Additionally or alternatively, the flexible membrane connector 22 may include a spring 23 that applies an elastic force ( Figure 4 ). For example, the structure 12 may include a segmented portion 27, at least one spring 20 (which may be part of the counter electrode 16 or not part of the counter electrode 16). The membrane electrode 14 may be elastically suspended to the spring 23 (or supported or fixed by the spring 23). The spring 23 may have at least one, some or all of the features of the at least one spring 20 described above (so these features are not repeated here). The spring 23 may be elastically deformable at least as a result of the movement of the membrane electrode 14 in part. When the spring 23 is provided, in Figure 3 The cutouts or holes shown in the figure can be avoided. The spring 23 can allow the membrane electrode 14 to be connected to the membrane electrode terminal 32 through the segmented portion 27. The spring 23 can be a conductive material. Instead of a single spring 23, multiple springs can be used.

[0048] A hybrid solution can also be obtained: the membrane electrode 14 can be partly suspended and partly supported by a structure 12 with low tensile stress.

[0049] Figure 5 A variation is shown in which the membrane electrode 14 is inserted between the first pair of electrodes 16 and the second pair of electrodes 17 and is spaced apart from the first pair of electrodes 16 and the second pair of electrodes 17 by a first gap 18 and a second gap 19, respectively. At least one spring 20 may be located between the membrane electrode 14 and the first pair of electrodes 16 (e.g., the most exposed or outermost pair of electrodes), but no spring is provided between the membrane electrode 14 and the second pair of electrodes 17 (e.g., the more internal or non-exposed pair of electrodes). In some examples, the spring 20 may be provided to connect the membrane electrode 14 to both the first pair of electrodes 16 and the second pair of electrodes 17. In the latter case (the spring 20 connects the membrane electrode 14 to both the first pair of electrodes 16 and the second pair of electrodes 17), the membrane electrode 14 and the first pair of electrodes 16 and the second pair of electrodes 17 may be operated as two different capacitors (e.g., two series capacitors) with variable capacitance based on pressure.

[0050] Figures 6 to 8 An example of the elements of the spring 20 and the counter electrode 16 is shown in a horizontal plane.

[0051] exist Figure 6 In the embodiment, the membrane side foot 20a of the spring 20 (the membrane side foot 20a may be adjacent to the surface 14a of the membrane electrode 14) is adjacent to the membrane electrode 14 (not shown). The counter electrode side foot 20b of the spring 20 is adjacent to the surface 16b of the counter electrode 16. Figure 6 and Figure 1 , Figure 2 , Figure 4 and Figure 5 Comparatively understood, while the feet 20a and 20b may extend generally in a horizontal direction, the main portion 20c of the spring 20 may extend generally in an oblique direction. It has been noted that the length of the main portion 20c of the at least one spring 20 is (generally) not critical.

[0052] The at least one spring 20 may be a conductive material (eg, a doped semiconductor material or a metal material), which may be the same material as the counter electrode 16. In an example, the at least one spring 20 and the counter electrode 16 may be integral with each other.

[0053] In order to avoid a short circuit between the membrane electrode 14 and the counter electrode 16 via at least one spring 20, the membrane electrode 14 may have a non-conductive island (e.g., in some parts of the surface, at least in the surface 14a). Therefore, even if the at least one spring 20 can be a metal or a conductive material, it will not cause a short circuit between the counter electrode 16 and the membrane electrode 14. Typical materials for at least one spring 20 can be polysilicon or SiNi. As an additional or alternative to using (one or more) islands, at least one spring 20 can have an electrical insulating layer on the outside. In other variations, at least one spring 20 can be an electrically insulating material.

[0054] Figure 7 An example is shown, where relative to Figure 1 The counter electrode 16 (ie, different from Figure 6 ). In this example, at least one spring 20 is integral with and of the same material as the counter electrode 16. A membrane side foot 20a may abut on the membrane electrode 14 (ie, the exposed surface 14a of the membrane electrode 14).

[0055] Figure 8 Another example is shown, where relative to Figure 1 The counter electrode 16 is shown from below, the elements 24, 25 and 14 not being shown. As can be seen, in this case the main portion 20c of the at least one spring 20 has a helical shape, thus increasing the elastic properties of the at least one spring 20. Other shapes may be chosen.

[0056] Fig. 9An example is shown in which at least one spring is at least one bimorph spring 30. The at least one bimorph spring 30 may be a spring that, when manufactured, moves the membrane electrode 14 (in the thickness direction, as indicated by the arrow 30') toward a position farther from the counter electrode 16, i.e., naturally increases the height of the gap 18. The at least one bimorph spring 30 may be such that a main portion 30c between a membrane side foot 30b (adjacent to the counter electrode 16) and a membrane side foot 30a (adjacent to the membrane electrode 14) is formed by a pair of intermediate portions (e.g., different materials) arranged adjacent to each other.

[0057] After removing the sacrificial layer, the range of movement can be significantly increased using a bimorph spring 30 bent from the counter electrode 16. Thus, the limitations in reaching high sound pressure levels, typical for the prior art, are overcome.

[0058] exist Fig. 9 In this example, the relative position between the membrane electrode 14 and the counter electrode 16 is relative to Figure 1 The example of is reversed. This reversal can be performed for any of the examples above or below.

[0059] Fig.18 Another example of the sensor 10 is shown, in which at least one (e.g., multiple) vertical springs 60 constitute a vertical spring, which is extended along the thickness direction through the gap 18. At least one vertical spring 60 can be made of a flexible material. Here, at least one vertical spring 60 can be obtained by a vertical connection between the membrane electrode 14 and the counter electrode 16.

[0060] Overall, the above examples present several important advantages. The compliance of the membrane electrode 14 is generally not defined by tensile stress, and the compliance of the membrane electrode 14 is generally not affected by external forces. Instead, the compliance of the membrane electrode 14 is generally determined by the design and the bending stiffness of the material used to make the at least one spring 20, 30, 60. Importantly, the bending stiffness of the material is a particularly stable parameter: the characteristics of the sensor will not change easily over time, and nominally identical sensors will have the same or similar behavior.

[0061] High stability and yield can be achieved for sensor production. Calibration functions can usually be avoided, as this ensures that the actual parameters of different sensors with the same nominal parameters do not vary too much.

[0062] System costs may also be reduced.The counter electrode(s) 18 and / or 19 may be designed to have thinner layers and greater acoustic transparency, thus reducing noise contribution and resulting in a higher signal-to-noise ratio SNR.

[0063] In addition, reliability is improved. In the event of particle intrusion, the local compliance of the membrane electrode 14 can be modified, but at least by means of the elastic effect exerted by the at least one spring 20, 30 or 60, the overall sensitivity change is limited.

[0064] In several examples, at least one surface of the membrane electrode 14 (e.g., surface 14a facing the counter electrode 16 but spaced apart from the counter electrode 16 by at least one spring) and / or at least one surface of the counter electrode 16 (e.g., surface 16b facing the membrane electrode 14 but spaced apart from the membrane electrode 14 by at least one spring) may be a non-protrusion surface: protrusions or other protrusions may not be completely necessary. This is because at least one spring 20, 30 or 60 can maintain a safe distance between the membrane electrode 14 and the counter electrode 16. Therefore, the following will not be possible: in operation, the membrane electrode 14 and the counter electrode 16 will contact each other, thereby remaining attached to each other by virtue of unintended electrostatic attraction. Nevertheless, a small amount of protrusions can be provided to increase safety, and when the membrane electrode 14 contacts the counter electrode 16, at least a little gap is maintained between the membrane electrode 14 and the counter electrode 16.

[0065] exist Figure 5 In the example of FIG. 1 , although the surface 14a separated from the first counter electrode 16 by at least one spring 20 is protrusion-free, the surface 14b has a protrusion 14b', which protrudes toward the second counter electrode 17 in the second gap 19. Therefore, in the case of accidental contact between the membrane electrode 14 and the counter electrode 16, the protrusion 14b' can prevent the membrane electrode 14 from being completely attached to the counter electrode 16 by electrostatic attraction. By avoiding complete attachment between the membrane electrode 14 and the counter electrode 16, the protrusion 14b' can therefore be used in a gap (such as, gap 19) where there is no spring.

[0066] Figures 10 to 14 An example of a method for manufacturing a sensor as described above is shown (e.g., Figure 1 Manufacturing steps of the sensor 10) method.

[0067] first( Fig.10 ), a substrate 24 (which may include a stop layer 28) may be fabricated.

[0068] The membrane electrode 14 may be placed or otherwise prepared on the substrate 24 and / or the stop layer 28 (where the flexible membrane connector 22 includes such as Figure 3 In the case of the cutouts or holes 22d shown, the cutouts or holes 22d) may be made or placed before the membrane electrode 14 is applied to the substrate 24 or the stop layer 28, or after the membrane electrode 14 is applied to the substrate 24 or the stop layer 28.

[0069] Subsequently, a capping material 26 (which may be a sacrificial material that will subsequently be at least partially removed) may be deposited on the substrate 24 ( Fig.11 ), for example at least in the region that will constitute the gap 18 and / or in a peripheral portion of the structure 12. The capping material 26 may be a capping oxide.

[0070] At least one hole 26a (e.g., a through hole) can be implemented, for example, in a selected location of the cover material 26 (e.g., which will accommodate at least one spring 20). The at least one hole 26a can be conical or inclined (other shapes are also possible). Multiple holes 26a preferably have side wall angles that are the same as each other or vary by a maximum of 1% or 5% in order to obtain springs 20 with the same or very similar spring constants. At least one hole 26a can be obtained by etching (e.g., by using dry or wet TEOS etching) or other removal techniques. At least one hole 26a can at least partially expose the surface 14a, and at least one spring 20 will be adjacent to the surface 14a. The exposed portion of the surface 14a can correspond to, for example, a non-conductive island of the surface 14a: in the case where the spring will be a conductive and / or highly doped material, the island will allow the membrane electrode 14 to be insulated from the counter electrode 16. For example, the non-conductive island can be deposited after the generation of the hole 26a.

[0071] As shown in FIG. 12 , at least one spring 20 may be prepared, for example, by depositing material over at least one hole 26 a, and in particular depositing material over (one or more) surfaces of at least one hole 26 a. Fig.12 As shown, the portion of the spring 20 adjacent to the membrane electrode 14 will constitute the membrane-side foot 20a of the spring 20. The portion of the spring 20 on the other side relative to the foot 20a (and which may protrude in the flush direction) will constitute the counter-electrode-side foot 20b of at least one spring 20. The middle portion of the spring 20 that extends obliquely along the boundary of the hole 26a will constitute the main portion 20c of at least one spring 20.

[0072] The electrode side foot 20b (e.g., the upper side of the electrode side foot 20b in the thickness direction) may be exposed. Therefore, the upper side of the electrode side foot 20b and the layer of the covering material 26 may be caused to be flush with each other in the upper surface 26e thereof in the thickness direction. Fig.13 As shown in FIG. 2 , the flush upper surface 26e will be used in the subsequent step of preparing the mechanical contact between the electrode 16 and the at least one spring 20. In order to make the upper surface 26e more flush, chemical mechanical polishing may be performed.

[0073] In a subsequent step, the counter electrode 16 can be prepared and / or configured so as to abut against at least one spring 20 (e.g., on the counter electrode side leg 20b). Thereafter, the remaining region(s) of the covering material 26 (e.g., at least those regions occupying the volume to be occupied by the gap 18) can be etched or otherwise removed to obtain Figure 1 structure.

[0074] The counter electrode 16 and the at least one spring 20 may be made of the same material (see Fig.19 ).

[0075] In the above and below methods, the membrane electrode 14 may be the first element, and the counter electrode 16 may be the second element. However, the operation may be reversed so that the first element to be placed on the substrate 24 is the counter electrode 16, and the membrane electrode 14 is the second element to be placed on the substrate 24.

[0076] Figures 14 to 17 shows the method for making and Figure 5 The sensor is similar to the double electrode sensor method.

[0077] Fig.14 The step in which a second (more inner) counter electrode 17 is placed over the substrate 24 and / or the cover layer 26 is shown.

[0078] If you can Fig.15 As seen in FIG. 1 , a second layer 26b of a capping material (eg, a capping oxide) may be deposited over the second counter electrode 17. Thereafter, the membrane electrode 14 may be deposited over the second layer 26b of the capping material.

[0079] As in Fig.16 As shown in FIG. 1 , a third layer 26c of cover material (cover oxide) may be placed over the membrane electrode 14. Thereafter, for example after holes 26a (eg, tapered holes or oblique holes) have been prepared in the third layer 26c of cover material, at least one spring 20 is placed.

[0080] Afterwards, if Fig.17 As shown, the first (more outer) counter electrode 16 can be placed on the at least one spring 20 and the third layer 26c of the covering material. Thereafter, the layers 26, 26b and 26c of the covering material can be at least partially etched or otherwise removed. In the case where it is desired to make the at least one spring 20 and the first counter electrode 16 from the same material, Fig.13 A similar procedure of the variation of can be performed. Basically, when reaching step f( Fig.16 ) Fig.12 and Fig.13 Any of the steps discussed may be performed.

[0081] When bimorph spring(s) 30 are used, an advantage is achieved: after the cover material 26 has been removed, the bimorph spring 30 will flex, thus naturally increasing the height of the gap 18 .

[0082] Fig.18 Another example of a vertical spring 60 (eg extending in the thickness direction) with a flexible material is shown. Here, the spring may be obtained by a vertical connection between the membrane electrode 14 and the counter electrode 16 .

[0083] To make Fig.18 For example, at least one of the following steps may be performed:

[0084] 1) Etching at least one vertical hole into the cover material 26;

[0085] 2) Filling at least one vertical hole with a material that is more etch-resistant than the covering material, thereby creating at least one pillar extending from the membrane electrode 14 in the thickness direction.

[0086] 3) Etching the remaining capping material (and the more etch-resistant at least one pillar, resistant to the etchant).

[0087] 4) Applying the counter electrode 16 (with the spring 60 attached thereto) to the etched portion, the counter electrode 16 abutting against at least one of the pillars (the pillars are thus used as spacers).

[0088] 5) Etching at least one pillar (in some cases, the pillar may remain as part of the counter electrode 16).

[0089] The shape of the spring 60 can vary; it can be a long, straight cantilever, a ring structure, a helical structure, or any other shape.

[0090] For at least one of the above steps, the example of removing materials as described above can be performed by etching (e.g., dry etching or wet etching). For at least one of the above steps, the etching can be anisotropic etching or isotropic etching. For at least one of the above steps, TEOS etching can be used.

[0091] For example, in order to remove material, at least one of the above steps may include a chemical mechanical polishing step.

[0092] When inserting a material (eg, covering a material), at least one of the above steps may include a lithography step (eg, a photolithography step).

Claims

1. A sensor (10), comprising: Structure (12); a membrane electrode (14) which is deformable as a result of being subjected to pressure and which is in contact with the structure (12); a counter electrode (16) mechanically connected to the structure (12) and separated from the membrane electrode (14) by a gap (18); at least one spring (20) between the membrane electrode (14) and the counter electrode (16) so as to apply an elastic force between the membrane electrode (14) and the counter electrode (16); as well as A flexible membrane connector (22) mechanically connects the membrane electrode (14) to the structure (12) and includes a cutout or hole (22d) corresponding to a portion (22b) of the membrane electrode (14) in contact with the structure (12).

2. The sensor according to claim 1, wherein: The flexible membrane connector (22) is configured to deform elastically at least partly as a result of a bending or movement or deformation of the membrane electrode (16) or a main part of the membrane electrode (16).

3. The sensor according to claim 1, wherein: The cutout or hole (22d) of the flexible membrane connector (22) is arched and / or concentric with the edge (14r) of the membrane electrode (14).

4. The sensor according to any one of claims 1 to 3, wherein: The flexible membrane connector (22) comprises springs (22, 23) which mechanically connect the membrane electrode (14) and the structure (12).

5. The sensor according to claim 4, wherein: The membrane electrode (14) is inserted between a first pair of electrodes (16) and a second pair of electrodes (17), and is spaced apart from the first pair of electrodes (16) and the second pair of electrodes (17) by a first gap (18) and a second gap (19), respectively.

6. The sensor according to claim 1, wherein: The at least one spring (30) is a bimorph spring.

7. The sensor according to claim 1, wherein: The membrane electrode (14) is cantilevered and connected to the structure (12).

8. The sensor according to claim 1, wherein: The at least one spring (20) comprises a membrane side foot (20a, 30a) and a counter electrode side foot (20b, 30b), wherein the membrane side foot (20a, 30a) is adjacent to the membrane electrode (14), and the counter electrode side foot (20b, 30b) is adjacent to the counter electrode (16).

9. The sensor according to claim 1, wherein: The at least one spring (20) comprises a plurality of springs.

10. The sensor according to claim 9, wherein: The plurality of springs (20) is an array or matrix of springs (20).

11. The sensor according to claim 1, wherein: The flexible membrane connection between the membrane electrode (14) and the structure (12) is stress-free.

12. The sensor according to claim 1, wherein: The membrane electrode (14) has at least one non-conductive island, and the at least one spring (20) is adjacent to the at least one non-conductive island, so that the at least one spring (20) is electrically insulated from the membrane electrode (14).

13. The sensor according to claim 1, wherein: The at least one spring (20) includes an inclined portion (22c) in the gap (18). The sensor according to claim 1 , implemented as a chip or a package.

15. A microphone device comprising a sensor according to any one of the preceding claims.

16. A method for manufacturing a semiconductor pressure sensor and / or an acoustic sensor, comprising: Preparing a first element (14, 16) on a substrate (24), wherein the first element (14, 16) is selected between a membrane electrode (14) and a counter electrode (16); preparing at least one spring element (20, 30) to abut against said first element (14, 16); preparing a second element (14, 16) such that the at least one spring element (20, 30) abuts on the second element (14, 16) and is elastically connected to the first element and the second element, wherein the second element (14, 16) is an element selected between the counter electrode (16) and the membrane electrode (14) and not selected for the first element, and A flexible membrane connector (22) is prepared by modifying a portion of the membrane electrode (14) to form a cutout or hole at the periphery of the membrane electrode (14).

17. The method according to claim 16, further comprising: depositing a sacrificial material (26) over the first element (14, 16) after the first element (14) has been prepared; The at least one spring element (20) and the second element (16) are produced by at least one of the following steps: removing the sacrificial material (26) in the selected location (26a); depositing spring element material over the selected location (26a); depositing a second element material over the spring element material; as well as The remaining sacrificial material (26) is removed.

18. The method according to claim 16 or 17, wherein The spring element material is the same material as the first element material or the second element material.

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