KR100451168B1 - Double action derivable electrostatic micro electrode and manufacturing method thereof - Google Patents

Abstract

The present invention relates to an electrostatic microelectrode capable of driving in both directions and a method of manufacturing the same. Bidirectional electrostatic fine electrode according to the present invention, the first electrode; A second electrode spaced apart from a predetermined distance on one side of the first electrode to maintain insulation from the first electrode; And a third electrode which is insulated from the first electrode and is arranged in a layered manner with the second electrode with an insulating layer interposed therebetween along the thickness direction of the second electrode, wherein the first electrode and the second electrode are disposed. One of the combination of the electrode and the third electrode is fixed and the other is characterized in that flow along the thickness direction. Thereby, the size and weight of the system can be reduced and the response speed can be improved.

Description

DOUBLE ACTION DERIVABLE ELECTROSTATIC MICRO ELECTRODE AND MANUFACTURING METHOD THEREOF}

The present invention relates to an electrostatic microelectrode capable of driving in both directions and a manufacturing method thereof, and more particularly, an electrostatic microelectrode capable of driving in both directions to reduce the size and weight of a system and to improve a response speed. And to a method for producing the same.

MEMS (MicroElectroMechanical System) refers to a micro system or micro precision machine, usually a few micrometers in size, and is called a micro system, a micro machine, a micro mechatronics, or the like. What can be easily realized as the current MMS technology is a sensor and actuator having a relatively simple and specific function.

Such MMS technology includes sensor fields such as a speedometer, an accelerometer, a flow meter, a hygrometer, a pressure gauge, and a thermometer; Information fields such as an HDD head, an AFM or an STM using an STM; Medical and biotechnology such as endoscopy, cell or DNA manipulators; Fluid element fields such as micro pumps, micro valves, micro component analyzers, and fluid logic elements; It is applied to optical and imaging fields such as micro mirrors, optical waveguides and optical couplers.

On the other hand, it is manufactured using such MMS technology, it is fine to have a comb-shaped finger (Pob) with a variety of metals such as polycrystalline silicon, single crystal silicon (Single Crystalline Silicon) or aluminum or nickel A micro-actuator or a micro-driver which forms an electrode, and arranges the electrodes so that each finger is transversely transverse to the displacement direction and uses electrostatic force induced on the sidewalls of the overlapping fingers as a driving force, and the overlapping fingers are separated by physical or chemical forces. There is a capacitive sensor that detects and outputs a change in capacitance between fingers when displaced.

By the way, in the micro-electrode used in the conventional micro driver and the capacitive sensor, only the attraction force that pulls the two electrodes charged by the applied voltage difference to each other acts and can be driven only in a single direction. Since the micro driver should be installed in every necessary direction, there is a problem that the size and weight of the overall system are increased and the response speed is reduced.

Accordingly, it is an object of the present invention to provide a bidirectionally driven electrostatic microelectrode capable of reducing the size and weight of a system and improving a response speed, and a method of manufacturing the same.

1 is a perspective view of a bidirectional drive electrostatic fine electrode according to an embodiment of the present invention,

2 is a plan view of FIG.

3 and 4 are cross-sectional views taken along lines III-III and IV-IV of FIG. 2, respectively;

5 is a view for explaining the driving principle of the fine electrode of FIG.

6 is an enlarged view illustrating main parts of FIG. 5;

7A to 7G are diagrams for explaining a method of manufacturing a bidirectional electrostatic microelectrode according to an embodiment of the present invention, respectively.

Explanation of symbols on the main parts of the drawings

10: first electrode 11: first finger

20: second electrode 21: second finger

30: third electrode 31: third finger

40: insulation layer

The object is, according to the present invention, a first electrode; A second electrode spaced apart from a predetermined distance on one side of the first electrode to maintain insulation from the first electrode; And a third electrode which is insulated from the first electrode and is arranged in a layered manner with the second electrode with an insulating layer interposed therebetween along the thickness direction of the second electrode, wherein the first electrode and the second electrode are disposed. One of the combination of the electrode and the third electrode is achieved by a bidirectionally driven electrostatic microelectrode, characterized in that the other is fixed and flows along the thickness direction.

Here, the first electrode, the second electrode and the third electrode is preferably configured to include a plurality of fingers alternately arranged horizontally in the flow direction.

The first electrode may flow along the thickness direction, and the second electrode and the third electrode may be fixedly installed.

It is preferable to further include a suspension structure for suspending the first electrode so that the first electrode is positioned overlapping between the second electrode and the third electrode along the thickness direction.

The suspension structure is an elastic body in which heterogeneous materials having different residual stresses are stacked, and the suspension structure overlaps the first electrode along the displacement direction between the second electrode and the third electrode by a residual stress difference. Positioning is effective.

The suspension structure is a bimetal elastic body in which materials having different thermal expansion coefficients are laminated, and the suspension structure is preferably configured to position the first electrode between the second electrode and the third electrode by an applied electric power. .

The suspension structure includes an elastic body connected to one side of the first electrode and a conductive thin film layer formed on the surface of the elastic body via a piezoelectric material, and the suspension structure is applied with a predetermined voltage between the two conductive thin film layers. It is effective to configure the first electrode to be positioned between the second electrode and the third electrode.

Preferably it further comprises a damping means for damping the flow of the first electrode.

The first to third electrodes may be configured to be relatively moved along the thickness direction in proportion to the potential difference input to each electrode.

Preferably, the first to third electrodes are configured to detect and output a change in capacitance corresponding to the displacement difference of each electrode.

On the other hand, according to another field of the present invention, along the thickness direction to form a first electrode formed on any one side, and the second electrode and the third electrode which are spaced apart from each other by a predetermined distance insulated from the first electrode Preparing a base material having lower silicon and upper silicon disposed therebetween; Selectively removing a portion of the lower silicon to expose the insulating layer and a remaining region corresponding to the third electrode by using a series of semiconductor fabrication techniques; Selectively removing the upper silicon to form the first electrode and the second electrode using the series of semiconductor fabrication techniques; Removing the remaining portion of the lower silicon used as a lower etching mask to form the third electrode; The first electrode, the second electrode and the third electrode is provided with a method for producing a bidirectionally-driven electrostatic fine electrode comprising the step of arranging to overlap each other in the displacement direction.

Hereinafter, with reference to the accompanying drawings will be described in detail with respect to the present invention.

1 is a perspective view of a bidirectionally driven electrostatic microelectrode according to an embodiment of the present invention, FIG. 2 is a plan view of FIG. 1, and FIGS. 3 and 4 are lines III-III and IV-IV of FIG. 2, respectively. 5 is a view for explaining a driving principle of the fine electrode of FIG. 1, FIG. 6 is an enlarged view of the main part of FIG. 5, and FIGS. 7A to 7G are each according to an embodiment of the present invention. It is a figure for demonstrating the manufacturing method of the electrostatic microelectrode which can drive a direction. As shown in these figures, the bidirectionally driven electrostatic microelectrode may be alternately disposed with the first electrode 10 having the plurality of first fingers 11 and the first fingers 11. A second electrode 20 having a plurality of second fingers 21 so as to be formed, and a second finger 21 formed below the second electrode 20 with the insulating layer 40 interposed along the thickness direction. It is configured to include a third electrode 30 having a plurality of third finger 31 formed under the ().

The first electrode 10, the second electrode 20, and the third electrode 30 may be vacuum or air so as to insulate the first finger 11, the second finger 21, and the third finger 31 from each other. And an insulating fluid or a free space, and the first electrode 10 has a damping element L for damping the flow and is configured to be movable along the thickness direction. The second electrode 20 and the third electrode 30 are connected to a substrate or a fixed structure 42 that provides a predetermined reference position.

One side of the first electrode 10 has a fixed portion 43 at one end so that the first finger 11 may be disposed at a position overlapping with the second finger 21 and the third finger 31 along the displacement direction. The other end of the elastic suspension structure shown by the coil spring 41 fixed to the connection is installed, and the insulating layer 40 formed between the second electrode 20 and the third electrode 30 is the second electrode 20. ) And the material and thickness (t) are appropriately configured so that breakdown does not occur even when the difference between the voltage applied to the third electrode 30 and the third electrode 30 is maximized.

Here, the elastic suspension structure, the first finger 11 is provided with a predetermined weight in the self-load of the elastic body, the damping element (L) and the first electrode 10 or the self-load of the first electrode 10 The second finger 21 and the third finger 31 may be configured to overlap each other along the displacement direction, and the elastic suspension structure is formed by stacking dissimilar materials having different residual stresses to form a first suspension by the stress difference. (11) may be configured to overlap each other with the second finger 21 and the third finger (31).

In addition, the elastic suspension structure, by joining two metals having different thermal expansion coefficients in face-to-face contact with each other to form a bimetal-type elastic suspension structure and applying electric power to the elastic suspension structure to induce thermal strain force to the first finger 11 May be configured to overlap the second finger 21 and the third finger 31, and the piezoelectric material capacitor structure formed by inserting a piezoelectric material such as PZT and ZnO between the conductive thin film layers is laminated on the elastic suspension structure. By applying a predetermined voltage between the conductive thin film layers, the first finger 11 may be formed to overlap the second finger 21 and the third finger 31 by using a so-called Piezoelectric Effect.

On the other hand, when using the first to third electrodes (10, 20, 30) as a micro driver, a separate metal to apply a voltage to each of the first to third electrodes (10, 20, 30) Alternatively, each of the lines 45a to 45c configured in the form of a wiring pad or the like is provided, wherein the first to third electrodes 10, 20, and 30 adjacent to each other are disposed to overlap each other along the displacement direction. The driving force acting between the first finger 11 and the second finger 21 and the third finger 31 is represented by the following equation (1).

Here, F is the force acting on the first electrode (10), g is a gap in each finger, l is overlapped in the direction perpendicular to the cross-sectional _{length, V m, V u, V} d is the first electrode, respectively (10), the voltage applied to the second electrode 20 and the third electrode 30, respectively, and ε is a constant.

As can be seen in Equation 1, the difference between the voltages applied to the first electrode 10 and the second electrode 20 is the difference between the voltages applied to the first electrode 10 and the third electrode 30, respectively. If larger than the first electrode 10 is moved to the upper side of the drawing, if smaller than the lower side of the drawing. That is, the coil spring 41 is connected to the bidirectional driving force determined by the voltage difference applied to each electrode 10, 20, 30 and the fixing part 43 to suspend the first electrode 10. The displacement of the first electrode 10 is determined at the point where the restoring force acting by the elastic modulus 탄성 of the elastic suspension structure implemented is mutually balanced, and when the voltage applied to each electrode is removed, the restoring force of the coil spring 41 is removed. As a result, the first electrode 10 returns to the initial position.

When the first to third electrodes 10, 20, and 30 are used as the fine electrodes of the capacitive sensor, the capacitance (capacitance) between the electrodes is represented by Equation 2 below.

Here, C ₁₂ is the capacitance by the first electrode 10 and the second electrode 20, and C ₁₃ is the capacitance by the first electrode 10 and the third electrode 30.

Here, the differential component capacitance C of the two capacitors is represented by Equation 3 below.

When the first electrode 10 is moved in the driving direction by the displacement Δd by the physical quantity or the stoichiometry to be detected, the change amount ΔC of the differential component capacitance capacitance is expressed by Equation 4 below.

That is, the differential component capacitance corresponds to twice the amount of change in capacitance of the conventional unidirectional capacitive sensor, and the increase in the amount of change in capacitance implies an improvement in sensitivity and resolution of the capacitive sensor.

Referring to FIGS. 7A to 7F, a method of manufacturing a bidirectionally driven electrostatic microelectrode having such a device characteristic will be described below. Here, each left side (a) of FIGS. 7A to 7B is a view corresponding to FIG. 3, and a right side (b) is a view corresponding to FIG. 4.

According to an embodiment of the present disclosure, a method of manufacturing a bidirectional electrostatic microelectrode according to an embodiment of the present disclosure may include the insulating layer 40 along a thickness direction so as to be the first to third electrodes 10, 20, and 30 described above. Preparing a base material 50 having the upper silicon 51a and the lower silicon 52a arranged in a layer spaced therebetween, and corresponding to the third electrode 30 provided with a plurality of third fingers 31. Selectively removing the lower silicon 52a, and selectively removing the upper silicon 51a so that the first electrode 10 and the third electrode 30 having a plurality of fingers can be formed; Removing the remaining portion of the portion used as the lower silicon etching mask 52b to form the third electrode 30, and the first electrode 10 along the thickness direction of the second electrode 20 and the third electrode. It is configured to include a step so as to overlap with (30).

The base material 50 to be the first to third electrodes 10, 20, and 30 may include upper silicon 51a to be the first electrode 10 and the second electrode 20, as shown in FIG. 7A. A so-called silicon on insulator (SOI) having a lower silicon 52a to be the third electrode 30 and an insulating layer 40 that insulates the second electrode 20 and the third electrode 30 from each other. ) Is composed of a substrate. Here, the upper silicon 51a and the lower silicon 52a are formed to have a thickness corresponding to the thicknesses of the first to third electrodes 10, 20, and 30, and the insulating layer 40 is a buried oxide film. ) In the form of

When the base material 50 in the form of a wafer in which an oxide film is embedded is prepared, a cleaning process for removing contaminants on the surface is performed, and a photolithography process, a thin film deposition process, and the like on the surface of the lower silicon 52a, The shape of the lower silicon etch mask 52b is patterned on the surface of the lower silicon 52a by using a series of semiconductor manufacturing processes such as an etching process.

Next, as illustrated in FIG. 7B, a method such as silicon deep reactive ion etching, which is a kind of anisotropic etching technique, of the lower silicon 52a exposed between the lower silicon etching masks 52b may be performed. Thus, the insulating layer 40 is selectively removed in the vertical direction so that the insulating layer 40 is exposed. When the etching of the lower silicon 52a is completed, as shown in FIG. 7C, the lower silicon etching mask 52b is selectively removed.

The semiconductor described above has a shape of an upper silicon etch mask 51b for forming the upper microstructure 51c on the upper silicon 51a aligned with the lower microstructure 52c formed by selective removal of the lower silicon 52a. Patterning is carried out using a manufacturing process. At this time, in order to align the mask pattern to the shape of the lower silicon 52a, a double side alignment technique of micromachining technique is applied. The upper silicon 51a exposed between the upper silicon etching mask 51b patterns is selectively removed in the vertical direction until the insulating layer 40 is exposed by the silicon deep reactive ion etching technique described above as shown in FIG. 7C.

As shown in FIG. 7D, the silicon oxide insulating layer 40 exposed by selectively removing the upper silicon 51a is selectively removed by using wet etching or dry etching, as shown in FIG. 7D. And the upper fine structure 51c to be the third electrode 30.

After removing the silicon oxide film, the lower microstructure 52c exposed after the silicon oxide film is removed by using a silicon deep reactive ion etching technique from the upper silicon 51a side to the lower side using the upper silicon mask pattern as an etching mask is illustrated in FIG. 7E. As such, self-aligned upper and lower microstructures 51c and 52c are formed, respectively.

As shown in FIG. 7F, the plurality of first fingers are removed by removing the insulating layer 40 remaining on the upper side of the upper fine structure 51c and the upper silicon etch mask 51b formed on the upper side of the upper fine structure 51c. The first electrode 10 and the second electrode 20 having the 11 and the second finger 21 are formed, respectively. Here, the insulating layer 40 remaining below the first electrode 10 may be used as a fine electrode structure without removing the insulating layer 40.

Next, each electrode is separated into individual device units, and the second electrode 20 and the third electrode 30 are fixedly coupled to the fixing part structure 42 such as a substrate, and the thickness direction of the first electrode 10. By selecting any one of the various types of elastic suspension structures described above to enable flow along the to cause deformation to the connected elastic suspension structure, as shown in Figure 7g, the second electrode 20 along the thickness direction ) And the third electrode 30 so as to overlap each other.

As described above, according to the present invention, the first electrode and the second electrode and the third electrode which are spaced apart from each other by a predetermined distance so as to be insulated with respect to the first electrode, and arranged in layers with an insulating layer interposed therebetween in the thickness direction. By arranging one of the first electrode, the second electrode, and the third electrode in such a manner as to be movable along the thickness direction, the micro-drivers are installed in the required driving direction only by installing the micro driver in the required driving direction. Unlike the prior art which not only increases the weight but also hinders the response speed, a bidirectionally driven electrostatic microelectrode capable of reducing the size and weight of the system and improving the response speed is provided.

In addition, according to the present invention, the differential sensing is possible to increase the sensitivity and resolution of the capacitive sensor.

Further, according to the present invention, when applied to a micro driver, the maximum voltage required to obtain the same maximum driving distance can be reduced by about half, thereby reducing the power consumption required for driving.

Claims (11)

A first electrode; A second electrode spaced apart from a predetermined distance on one side of the first electrode to maintain insulation from the first electrode; And a third electrode which is insulated from the first electrode and is arranged in a layered manner with the second electrode with an insulating layer interposed therebetween along the thickness direction of the second electrode, wherein the first electrode and the second electrode are disposed. Any one of the combination of the electrode and the third electrode is fixed and the other one of the electrostatic microelectrode capable of flowing in the direction along the thickness direction. The method of claim 1, The first electrode, the second electrode and the third electrode is a two-way drive electrostatic fine electrode, characterized in that it comprises a plurality of fingers alternately arranged in the flow direction. The method according to claim 1 or 2, The first electrode is movable along the thickness direction, the second electrode and the third electrode is a two-way drive electrostatic fine electrode, characterized in that the fixed installation. The method of claim 3, And a suspension structure for suspending the first electrode such that the first electrode is positioned to overlap between the second electrode and the third electrode along the thickness direction. The method of claim 4, wherein The suspension structure is an elastic body in which heterogeneous materials having different residual stresses are stacked, and the suspension structure overlaps the first electrode along the displacement direction between the second electrode and the third electrode by a residual stress difference. Bidirectional driveable electrostatic microelectrode, characterized in that the positioning. The method of claim 4, wherein The suspension structure is a bimetallic elastomer in which materials having different thermal expansion coefficients are laminated, and the suspension structure is positioned between the second electrode and the third electrode by an applied electric power. Driven electrostatic fine electrodes. The method of claim 4, wherein The suspension structure includes an elastic body connected to one side of the first electrode and a conductive thin film layer formed on the surface of the elastic body via a piezoelectric material, and the suspension structure is applied with a predetermined voltage between the two conductive thin film layers. Wherein the first electrode is positioned between the second electrode and the third electrode. The method according to any one of claims 4 to 7, The electrostatic microelectrode of claim 2 further comprising a damping means for damping the flow of the first electrode. The method according to claim 1 or 2, The first to third electrodes are bidirectionally driven electrostatic fine electrodes, characterized in that the relative movement in the thickness direction in proportion to the potential difference input to each electrode. The method according to claim 1 or 2, And the first to third electrodes are configured to detect and output a change in capacitance corresponding to a displacement difference of each electrode. Lower silicon and upper portion having an insulating layer interposed therebetween so as to form a first electrode formed on one side, and a second electrode and a third electrode which are spaced apart from each other by a predetermined distance to be insulated from the first electrode. Preparing a base material on which silicon is disposed; Selectively removing a portion of the lower silicon to expose the insulating layer and a remaining region corresponding to the third electrode by using a series of semiconductor fabrication techniques; and using the series of semiconductor fabrication techniques Selectively removing the upper silicon to form an electrode and the second electrode; Removing the remaining portion of the lower silicon used as a lower etching mask to form the third electrode; And disposing the first electrode, the second electrode, and the third electrode so as to overlap each other in the displacement direction.