Metal-driven electrostatic micro-actuator with self-curling interdigital structure

Abstract

The invention discloses a metal-driven electrostatic micro-actuator with a self-curling interdigital structure. The metal-driven electrostatic micro-actuator comprises a substrate and a multi-circle tubular body which can be curled into at least two circles on the substrate, the multi-circle tubular body is formed by curling a planar interdigital structure made of a metal material, and the planar interdigital structure is formed by arranging a plurality of interdigitals in a staggered manner; the interdigitals comprise first interdigitals and second interdigitals, and the first interdigitals and the second interdigitals are arranged in a staggered manner; the first interdigital is electrically connected with the negative feeder line, the second interdigital is electrically connected with the positive feeder line, different voltages are connected to the negative feeder line and the positive feeder line, so that a potential difference exists between two adjacent circles of interdigital, electrostatic force is generated due to the existence of the potential difference, and the interdigital voltages between two adjacent circles are different in arrangement. The limitation that a traditional actuator is small in deformation range is broken through, the metal driving self-curling thin film technology and the interdigital structure are combined, the obtained electrode distance is small, the electrostatic force utilization rate is high, and the method can be used for reconstruction of other integrated circuit devices.

Description

Technical Field

[0001] The invention relates to the field of automatic control and micro-nano technology, in particular to a metal-driven self-curling interdigital structure electrostatic micro-actuator. Background Art

[0002] The structure of electrostatic actuator is easy to realize and has many applications. Due to its versatility, simplicity and high compatibility with IC manufacturing technology, it has become the most widely used actuator. Hot spots of typical micro-device applications include digital micromirrors in digital optical processors, electrostatically driven MEMS microswitches in optical communications, micro-inertial sensors-micro-gyros, micro-resonators made using the mechanical properties of materials, electrostatic micromotors, electrostatic force microscopes, and micro-motion platforms, micro-pumps, micro-valves, micro-tweezers, etc. also use electrostatic force as a driving source. MEMS electrostatic actuators, typically electrostatically driven cantilever beams, comb-tooth micro-actuators, etc., use the Coulomb force between two parallel plates to make one of the plates translate or rotate relative to the other plate. The magnitude and direction of the driving force are determined by the magnitude and direction of the bias voltage, but there are generally disadvantages such as a small adjustable range, a large spacing between electrodes, and a pull-in effect.

[0003] The Chinese patent with the announcement number CN113460953A discloses an electrostatic micro-actuator with a self-curling interdigital structure, which belongs to the field of automatic control and micro-nano technology. It includes a self-curling micro-tube that self-curls on a silicon substrate to form a multi-turn tube; the self-curling micro-tube includes a first protective layer, a stress layer, a conductive layer and a second protective layer from the outside to the inside; the stress layer is used to curl the body, and the conductive layer is an interdigital structure made of a good conductor material. The electrostatic micro-actuator can achieve dimensional conversion under maximum deformation, from a planar structure to a three-dimensional structure and then to a planar structure.

[0004] However, the above-mentioned self-curling interdigital electrostatic microactuator uses silicon nitride as the strain layer. However, when silicon nitride is used as the strain layer, another device is required to deposit silicon nitride using chemical vapor deposition, and holes are easily formed between the films, that is, there is a pinhole effect.

[0005] Therefore, a metal-driven self-curling interdigital electrostatic microactuator is proposed. Summary of the invention

[0006] The object of the present invention is to provide a metal-driven self-curling interdigital electrostatic microactuator, thereby solving or at least alleviating one or more of the above-mentioned problems and other problems existing in the prior art.

[0007] To achieve the above object, the present invention provides the following technical solution: a metal-driven self-curling interdigital structure electrostatic microactuator, comprising a substrate and a multi-turn tubular body capable of curling into at least two turns on the substrate;

[0008] The multi-turn tubular body is formed by curling a planar interdigital structure of a metal material, and the planar interdigital structure is formed by a plurality of interdigital fingers arranged in a staggered manner;

[0009] The interdigitated fingers include first interdigitated fingers and second interdigitated fingers, and the first interdigitated fingers and the second interdigitated fingers are arranged in a staggered manner;

[0010] The first interdigital finger is electrically connected to the negative electrode feeder, and the second interdigital finger is electrically connected to the positive electrode feeder. Voltages of different magnitudes are connected to the negative electrode feeder and the positive electrode feeder, so that there is a potential difference between the interdigital fingers of two adjacent circles. Electrostatic force is generated due to the existence of the potential difference. The interdigital finger voltages between two adjacent circles are arranged differently, and the deformation magnitudes and directions are different, so that the interlayer spacing between two adjacent circles of the multi-circle tubular body changes, and the multi-circle tubular body can achieve dimensional conversion under the maximum deformation state.

[0011] In the metal-driven self-curling interdigital structure electrostatic microactuator according to the present invention, optionally, the planar interdigital structure comprises an insulating layer and a strain and conductive layer, and the interdigital is formed by etching the strain and conductive layer;

[0012] The strain and conductive layer includes an adhesion layer, a strain layer and a conductive layer, wherein the conductive layer is deposited on the strain layer, the strain layer is deposited on the adhesion layer, and the adhesion layer is deposited on the insulating layer.

[0013] In the metal-driven self-curling interdigital structure electrostatic microactuator according to the present invention, optionally, the adhesion layer is a titanium metal layer with a deposition thickness of 5nm-15nm, the strain layer is a chromium metal layer with a deposition thickness of 10nm-50nm, and the conductive layer is a copper metal layer with a deposition thickness of 50nm-150nm.

[0014] In the metal-driven self-curling interdigital structure electrostatic microactuator according to the present invention, optionally, there is a potential difference between the interdigital fingers, and the generated electrostatic force can cause the multi-turn tubular body to deform, and the deformation effects include repulsion and opening, contraction to reduce the inner diameter, and increase the inner diameter.

[0015] In the metal-driven self-winding interdigital structure electrostatic microactuator according to the present invention, optionally, a sacrificial layer is deposited on the top of the substrate, and the insulating layer is deposited on the sacrificial layer.

[0016] In the metal-driven self-curling interdigital structure electrostatic microactuator according to the present invention, optionally, the substrate is a silicon substrate, and the sacrificial layer is a germanium metal layer.

[0017] In the metal-driven self-curling interdigital structure electrostatic microactuator according to the present invention, optionally, a protective layer is deposited on the conductive layer.

[0018] In the metal-driven self-curling interdigital structure electrostatic microactuator according to the present invention, optionally, both the protective layer and the insulating layer are aluminum oxide layers.

[0019] In the metal-driven self-curling interdigital structure electrostatic microactuator according to the present invention, optionally, its preparation process specifically includes the following steps:

[0020] S1, depositing a sacrificial layer and an insulating layer on the substrate in sequence;

[0021] S2, manufacturing a strain and conductive layer, depositing a strain layer on the adhesion layer, depositing a conductive layer on the strain layer, and operating the strain and conductive layers to form an interdigital structure;

[0022] S3, depositing the strain and conductive layer forming the interdigitated structure onto the insulating layer;

[0023] S4, depositing a protective layer on the strain and conductive layer;

[0024] S5, etching the strained layer, the adhesion layer, the insulating layer and the sacrificial layer to form an operating table;

[0025] S6, the protective layer begins to etch the operating table to form an etching window that exposes the substrate;

[0026] S7, etching the sacrificial layer. After the sacrificial layer is etched away, the structure above the sacrificial layer curls up to form a multi-turn tubular body due to the internal stress gradient.

[0027] In the metal-driven self-curling interdigital structure electrostatic microactuator according to the present invention, optionally, the strain and conductive layer are formed into an interdigital structure by electron beam deposition.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] Breaking the limitation of small deformation range of traditional actuators, the metal-driven self-curling film technology and interdigital structure are combined to obtain a small electrode spacing, high utilization rate of electrostatic force, and can be used for the reconstruction of other integrated circuit devices;

[0030] When silicon nitride is used as a strain layer, another device is required to deposit silicon nitride. When chemical vapor deposition is used, holes are easily formed between the films, that is, there is a pinhole effect. In this case, titanium is used as the adhesion layer and chromium is used as the strain layer. Using electron beam deposition, titanium, chromium and copper can be deposited simultaneously in one device. There are no holes between layers, which improves efficiency and yield. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a schematic structural diagram of the metal-driven self-curling interdigital electrostatic microactuator of the present invention;

[0032] Figure 2 This is a flow chart for preparing the metal-driven self-curling interdigital structure electrostatic microactuator of the present invention;

[0033] Figure 3 Schematic diagram of the planar interdigitated structure of metal-driven self-curling in Example 1 and Example 2 of the present invention;

[0034] Figure 4 It is a schematic diagram of the partial structure of the metal-driven self-curling interdigital structure electrostatic microactuator in Example 3 of the present invention;

[0035] Figure 5 Schematic diagram of the deformation structure of the electrostatic microactuator when the potential difference is 60V in Example 3 of the present invention;

[0036] Figure 6 This is a schematic diagram of the feeder distribution structure in Embodiment 3 of the present invention;

[0037] Figure 7 Schematic diagram of the deformation structure of the electrostatic microactuator when the potential difference is slightly 10V in Example 4 of the present invention;

[0038] Figure 8 Schematic diagram of the deformation structure of the electrostatic microactuator when the potential difference is 60V in Example 5 of the present invention.

[0039] In the figure: 1, substrate; 101, sacrificial layer; 2, insulating layer; 3, adhesion layer; 4, strain layer; 5, conductive layer; 6, protective layer; 7, first interdigital finger; 8, second interdigital finger; 9, negative electrode feed line; 10, positive electrode feed line; 12, multi-turn tubular body. DETAILED DESCRIPTION

[0040] The technical solution of the present invention is further described below with reference to the accompanying drawings and through specific implementation methods.

[0041] Among them, the drawings are only used for illustrative explanations, and they only represent schematic diagrams rather than actual pictures, and should not be understood as limitations on this patent; in order to better illustrate the embodiments of the present invention, some parts of the drawings may be omitted, enlarged or reduced, and do not represent the size of the actual product; for those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings may be omitted.

[0042] The same or similar numbers in the drawings of the embodiments of the present invention correspond to the same or similar parts; in the description of the present invention, it should be understood that if the terms "upper", "lower", "left", "right", "inner", "outer", etc. appear to indicate the orientation or position relationship, it is based on the orientation or position relationship shown in the drawings, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, the terms describing the position relationship in the drawings are only used for illustrative purposes and cannot be understood as a limitation on this patent. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0043] In the description of the present invention, unless otherwise clearly specified and limited, if the term "connection" or the like appears to indicate the connection relationship between components, the term should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two components or the interaction relationship between two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0044] Example 1

[0045] See also Figures 1 to 8 The present embodiment provides the following technical solution: a metal-driven self-curling interdigital structure electrostatic microactuator, comprising a substrate 1 and a multi-turn tubular body 12 that can be curled into at least two turns on the substrate 1, the multi-turn tubular body 12 is curled by a planar metal interdigital structure made of metal material, the planar metal interdigital structure is formed by a plurality of interdigital fingers arranged in an interlaced manner, the interdigital fingers include a first interdigital finger 7 and a second interdigital finger 8, the first interdigital finger 7 and the second interdigital finger 8 are arranged in an interlaced manner, the first interdigital finger 7 is electrically connected to a negative electrode feed line 9, and the second interdigital finger 8 is electrically connected to a positive electrode feed line 10. Connect, connect different voltages on the negative electrode feeder 9 and the positive electrode feeder 10, so that there is a potential difference between the interdigital fingers of two adjacent circles, and electrostatic force is generated due to the existence of the potential difference. According to the different arrangement of the interdigital voltage between the two adjacent circles, the deformation size and direction are different, so that the interlayer spacing between the two adjacent circles of the multi-circle tubular body 12 changes, and there is a potential difference between the interdigital fingers. The generated electrostatic force can cause the multi-circle tubular body 12 to deform, and there are multiple deformation effects, including repulsion and rebound, contraction to reduce the inner diameter, and increase the inner diameter. The size of the interdigital structure and the number of metal interdigital fingers in each circle have an impact on the deformation effect. The multi-circle tubular body 12 can achieve dimensional conversion in the maximum deformation state, that is, it can change from a plane structure to a three-dimensional structure and then to a plane structure.

[0046] In this embodiment, the planar interdigital structure includes an insulating layer 2, a strain and conductive layer, and a protective layer 6. The interdigital is etched from the strain and conductive layer. The strain and conductive layer includes an adhesion layer 3, a strain layer 4, and a conductive layer 5. The conductive layer 5 is deposited on the strain layer 4, and the protective layer 6 is deposited on the conductive layer 5. The strain layer 4 is deposited on the adhesion layer 3, and the adhesion layer 3 is deposited on the insulating layer 2. The protective layer 6 is deposited on the conductive layer 5. The protective layer 6 and the insulating layer 2 are both aluminum oxide layers, wherein the adhesion layer 3 is a titanium metal layer with a deposition thickness of 5nm-15nm, the strain layer 4 is a chromium metal layer with a deposition thickness of 10nm-50nm, and the conductive layer 5 is a copper metal layer with a deposition thickness of 50nm-150nm. A sacrificial layer 101 is deposited on the top of the substrate 1, and the insulating layer 2 is deposited on the sacrificial layer 101. The substrate 1 is a silicon substrate 1, and the sacrificial layer 101 is a germanium metal layer.

[0047] In this embodiment, the protection layer 6 and the insulation layer 2 are both aluminum oxide layers.

[0048] It should be noted that, in some embodiments, the sacrificial layer 101 can also be made of photoresist or silicon oxide material, the substrate 1 can be a flexible substrate such as metal or sapphire, manufactured using a semiconductor manufacturing process, the strain layer 4 can also be made of other stress-driven metal materials besides chromium, and the conductive layer 5 can also be made of other conductive metal materials besides copper.

[0049] like Figure 2 As shown, the preparation process of the metal-driven self-curling interdigital structure electrostatic microactuator of the present invention specifically includes the following steps:

[0050] S1, depositing a sacrificial layer 101 and an insulating layer 2 on a substrate 1 in sequence;

[0051] S2, manufacturing strain and conductive layers, depositing strain layer 4 on adhesion layer 3, depositing conductive layer 5 on strain layer 4, and forming interdigital structures on strain and conductive layers by electron beam deposition;

[0052] S3, depositing a strain and conductive layer forming a metal interdigital structure onto the insulating layer 2;

[0053] S4, depositing a protective layer 6 on the strain and conductive layer;

[0054] S5, etching the strained layer 4, the adhesion layer 3, the insulating layer 2 and the sacrificial layer 101 to form an operating table;

[0055] S6, the protective layer 6 begins to etch the operating table to form an etching window that exposes the substrate 1;

[0056] S7, etching the sacrificial layer 101. After the sacrificial layer 101 is etched away, the structure above the sacrificial layer 101 curls up to form a multi-turn tubular body 12 due to the stress gradient inside.

[0057] The present invention adopts metal-driven self-curling film technology to convert a planar interdigitated structure into a three-dimensional structure, and then realizes the transformation of the three-dimensional structure into a planar structure by electrostatic force, and an electrostatic microactuator with any number of turns can be obtained in the meantime.

[0058] Example 2

[0059] like Figure 3 As shown, the strain and conductive layer adopts an interdigital structure, with a total of 40 interdigital fingers, the interdigital dimensions are: 5um long, 0.3um wide, 0.3um interval, 0.5um feeder width, 24um long, 6.5um total width of the structure, copper is selected for the conductive layer 5, germanium is selected for the sacrificial layer 101, and the thickness of the electron beam evaporation is 100nm. The insulating layer 2 to avoid the influence of the pinhole effect adopts an aluminum oxide film. The strain and conductive layer are titanium, chromium, and copper from bottom to top, with a titanium thickness of 10nm, a chromium thickness of 30nm, and a copper thickness of 100nm. The thickness of the copper evaporated by the electron beam is 180nm. The germanium layer is etched with hydrogen peroxide. Under the stress gradient of chromium, the entire structure curls into a two-circle microtube structure, realizing the dimensional conversion from a planar interdigital structure to a three-dimensional structure.

[0060] Embodiment 3, as Figure 4-Figure 6 As shown in the figure, the curled structure is connected to the same feeder line along the same radial direction, with a high potential on the positive feeder line 10 and grounded on the negative feeder line 9. At this time, the interdigits of the first and second circles along the same radial direction have the same potential, but in the same circle, two adjacent interdigits are connected to different feeders and have different potentials. When the initial potential difference applied is 60V, the inner circle deforms more than the outer circle. At this time, the two circles are in contact, as shown in the figure. Figure 5 , the maximum deformation size is 0.35um. When the potential difference is increased, in addition to the electrostatic force between the two circles, there is also pressure from the inner circle to the outer circle, which makes the two circles gradually spread out and deform into a planar interdigitated structure.

[0061] Embodiment 4, as Figure 7 As shown, the thickness of the strain layer 4 is changed so that the prepared electrostatic microactuator satisfies the curling structure along the same radial direction, and the interdigits are connected on different feeders. A 10V voltage is applied to the positive feeder 10, and the negative feeder 9 is grounded. At this time, the interdigits of the first circle and the second circle along the same radial direction have different potentials, and the potentials of adjacent interdigits of the same circle are also different. At this time, there is a potential difference between the interdigits of the two circles, and the electrostatic force generated makes the inner and outer circles attract each other, and the inner and outer circles gradually approach each other, but because the inner and outer circles are the same structure, the final deformation effect is that the inner diameter of the electrostatic microactuator tends to decrease.

[0062] Embodiment 5, as Figure 8As shown, the size of each finger in Example 2 is increased to: a single interdigital length of 5um, a width of 0.75um, a spacing of 0.75um between two adjacent interdigital fingers, and other parameters such as the curling inner diameter remain unchanged. At this time, the number of interdigital fingers in the inner circle of the electrostatic microactuator obtained by curling is halved, and the curling structure is an interdigital finger connected to the same feeder along the same radial direction, with a high potential on the positive feeder 10 and grounded on the negative feeder 9. At this time, the interdigital fingers of the first circle and the second circle along the same radial direction have the same potential, but in the same circle, two adjacent interdigital fingers are connected to different feeders and have different potentials. Under a potential difference of 60V, the maximum deformation is 0.25um. Compared with the results of Example 2, the deformation effect is not as obvious as that of Example 2. It can be seen that the more interdigital fingers per circle, the greater the repulsive force and the more obvious the deformation. In addition, if the spacing between the two circles is reduced and the electrode spacing is reduced, the electrostatic force will obviously increase under the same potential difference, and the deformation displacement will be greater.

[0063] Parts not involved in the present invention are the same as the prior art or can be implemented by the prior art. Although the embodiments of the present invention have been shown and described, it is understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the attached claims and their equivalents.

Claims

1. A metal-driven self-curling interdigital electrostatic microactuator, characterized in that: It comprises a substrate (1) and a multi-turn tubular body (12) capable of being rolled into at least two turns on the substrate (1); The multi-turn tubular body (12) is formed by curling a planar interdigital structure of a metal material, wherein the planar interdigital structure is formed by a plurality of interdigital fingers arranged in a staggered manner; The interdigital fingers include first interdigital fingers (7) and second interdigital fingers (8), and the first interdigital fingers (7) and the second interdigital fingers (8) are arranged in a staggered manner; The first interdigital fingers (7) are electrically connected to the negative electrode feeder (9), and the second interdigital fingers (8) are electrically connected to the positive electrode feeder (10). Voltages of different magnitudes are connected to the negative electrode feeder (9) and the positive electrode feeder (10), so that there is a potential difference between the interdigital fingers of two adjacent circles. Due to the existence of the potential difference, an electrostatic force is generated. The interdigital fingers between two adjacent circles have different voltage arrangements and different deformation magnitudes and directions, so that the interlayer spacing between two adjacent circles of the multi-circle tubular body (12) changes. The multi-circle tubular body (12) can achieve dimensional conversion in the maximum deformation state.

2. The metal-driven self-curling interdigital electrostatic microactuator according to claim 1, characterized in that: The planar interdigital structure comprises an insulating layer (2) and a strain and conductive layer, and the interdigital is formed by etching the strain and conductive layer; The strain and conductive layer comprises an adhesion layer (3), a strain layer (4) and a conductive layer (5), wherein the conductive layer (5) is deposited on the strain layer (4), the strain layer (4) is deposited on the adhesion layer (3), and the adhesion layer (3) is deposited on the insulating layer (2).

3. The metal-driven self-curling interdigital electrostatic microactuator according to claim 2, characterized in that: The adhesion layer (3) is a titanium metal layer with a deposition thickness of 5nm-15nm, the strain layer (4) is a chromium metal layer with a deposition thickness of 10nm-50nm, and the conductive layer (5) is a copper metal layer with a deposition thickness of 50nm-150nm.

4. The metal-driven self-curling interdigital electrostatic microactuator according to claim 3, characterized in that: There is a potential difference between the interdigitated fingers, and the generated electrostatic force can cause the multi-turn tubular body (12) to deform, and the deformation effects include repulsion and rebound, contraction to reduce the inner diameter, and increase the inner diameter.

5. The metal-driven self-curling interdigital electrostatic microactuator according to claim 4, characterized in that: A sacrificial layer (101) is deposited on the top of the substrate (1), and the insulating layer (2) is deposited on the sacrificial layer (101).

6. The metal-driven self-curling interdigital electrostatic microactuator according to claim 5, characterized in that: The substrate (1) is a silicon substrate (1), and the sacrificial layer (101) is a germanium metal layer.

7. The metal-driven self-curling interdigital electrostatic microactuator according to claim 6, characterized in that: A protective layer (6) is deposited on the conductive layer (5).

8. The metal-driven self-curling interdigital electrostatic microactuator according to claim 7, characterized in that: The protective layer (6) and the insulating layer (2) are both aluminum oxide layers.

9. The metal-driven self-curling interdigital electrostatic microactuator according to claim 8, characterized in that: The preparation process specifically comprises the following steps: S1, depositing a sacrificial layer (101) and an insulating layer (2) in sequence on a substrate (1); S2, manufacturing a strain and conductive layer, depositing a strain layer (4) on the adhesion layer (3), depositing a conductive layer (5) on the strain layer (4), and operating the strain and conductive layers to form an interdigitated structure; S3, depositing a strain and conductive layer forming an interdigitated structure onto the insulating layer (2); S4, depositing a protective layer (6) on the strain and conductive layer; S5, etching the strained layer (4), the adhesion layer (3), the insulating layer (2) and the sacrificial layer (101) to form an operating table; S6, the protective layer (6) begins to etch the operating table to form an etching window that exposes the substrate (1); S7, etching the sacrificial layer (101). After the sacrificial layer (101) is etched away, the structure above the sacrificial layer (101) curls up to form a multi-turn tubular body (12) due to the stress gradient inside.

10. The metal-driven self-curling interdigital electrostatic microactuator according to claim 9, characterized in that: The strain and conductive layer is formed into an interdigital structure by electron beam deposition.

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