KR0158161B1 - Microswitch and manufacturing process of it - Google Patents

Abstract

It is an object of the present invention to provide a variable threshold micro switch capable of electrically adjusting a threshold of an acceleration or a voltage required for an electrode-to-electrode connection or a rapid change in capacitance within a single switch, and independently adjusting the bidirectional switch threshold; It is made of a silicon substrate, and the upper and lower portions of the longitudinal center portion are recessed with a predetermined width, so that the center portion is made of a small thickness portion in cross section, and both sides thereof are made of a large thickness portion, and a rectangular space is formed at the center portion thereof. A base plate which is formed; An inner and an outer thin film layer which is double coated on a portion of the base plate except for the lower side of the base plate, and is formed on the upper side of the space portion so that both sides in the longitudinal direction thereof are cut to form high information at both ends; A mass body attached to an intermediate portion of the high information at both ends and suspended; Upper and lower electrodes formed on both ends of the high information and the mass; Adhesive upper and lower electrodes formed on upper and lower surfaces of both base portions of the base plate; A band-shaped electrode is formed on one surface thereof, and a variable threshold micro switch including upper and lower glasses attached to upper and lower surfaces of a base plate in a direction orthogonal to high information at both ends thereof is provided.

Description

Variable threshold micro switch and its manufacturing method

1 is a perspective view of a micro switch according to the present invention.

2 is a cross-sectional view taken along the line A-A of FIG.

3 is a cross-sectional view taken along the line B-B in FIG.

4 is a view showing an initial deformation state to explain the operation principle of the present invention.

5 is a manufacturing process diagram of a micro switch according to the present invention.

6 is a graph of a performance experiment in which the amount of connection current according to the voltage applied between the electrodes of the micro-switch according to the present invention is measured.

7 is a graph diagram predicting the threshold acceleration adjustable range according to the adjustment of the voltage across the electrodes when the length of the high information at both ends of the micro-switch according to the present invention is different and the same mass is attached to the center.

8 is an embodiment of a conventional micro switch.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to micro-switches that are widely applied to automobiles, railway vehicles, aircraft, home appliances, industrial devices, and the like, and more particularly, to measure acceleration or voltage, and to operate the switches at measured values above a certain threshold. A variable threshold micro switch and a method of manufacturing the same.

For example, as an example of an integrated acceleration threshold switch in which a mass and a spring are manufactured using silicon, as shown in FIG. 8, a cantilever shape is formed at equal intervals in the space 102 formed in the middle of the silicon substrate 100. Many spring pieces 104 were integrally formed, and the mass body 106 was formed in the front-end | tip of these spring pieces 104. As shown in FIG.

In addition, terminals 108 are formed on upper surfaces of the spring pieces 104, and electrodes 112 are disposed at positions corresponding to the terminals 108 on the bottom surface of the glass plate 110 disposed on the upper surface of the silicon substrate 100. ), And the electrodes 112 thereof have a structure in which one end is connected to a terminal 114 disposed at one side of the silicon substrate 100.

The elastic force of the spring piece 104 and the mass of the mass body 106 are set differently so that the switch array in which the spring piece 104 and the mass body 106 are integrally formed may operate at various critical accelerations. .

However, in the cantilever-type threshold switch as described above, there are advantages in that it is possible to satisfy various threshold acceleration requirements by a plurality of switch strings, but the range of threshold accelerations to be measured and the threshold acceleration section are discontinuous and form a plurality of switch strings. By doing so, there is a problem that the size of the entire switch is increased.

In addition, there is a problem that can not compensate for the manufacturing error that occurs after the manufacture of the switch.

And another conventional example is the manufacturing method of the micro mechanical switch of Unexamined-Japanese-Patent No. 2-26033.

The present invention has been invented to solve the above problems, an object of the present invention is to electrically adjust the threshold of the acceleration or voltage required for the electrode-to-electrode connection or the rapid change in capacitance in a single switch, the bi-directional switch threshold The present invention provides a variable threshold micro switch and a method of manufacturing the same that can be independently adjusted.

Another object of the present invention is to control the residual stress in the thin film by changing the conditions of the thin film forming process, and through this, a variable threshold micro switch capable of controlling the initial deformation by using the bidirectional snap-through phenomenon of the double or multilayer thin film structure. And to provide a method for producing the same.

It is still another object of the present invention to provide a variable critical micro switch and a method of manufacturing the same material capable of integrating a spring, a mass, and an adhesive groove, and forming an etch stop layer and an insulating layer or an etch stop layer and a conductor using the same material. Is in.

Still another object of the present invention is to provide a variable threshold micro switch and a method of manufacturing the same in which self-diagnostic and experimental functions are incorporated.

In order to realize this, the present invention is made of a silicon substrate, the upper and lower portions of the central portion in the longitudinal direction is embedded with a predetermined width, the center portion is made of a small thickness portion in cross section and both sides are made of a large thickness portion. A base plate having a rectangular space portion at a central portion thereof;

An inner and outer thin film layer which is applied to a portion of the base plate other than the lower side of the space part and is formed to have high information at both ends by cutting both sides in the longitudinal direction on the upper side of the space part;

A mass body attached to an intermediate part of both height information and suspended;

Upper and lower electrodes formed on both ends of the high information and the mass;

Adhesive upper and lower electrodes formed on upper and lower surfaces of both base portions of the base plate;

A band-shaped electrode is formed on one surface thereof, and a variable threshold micro switch including upper and lower glasses attached to upper and lower surfaces of a base plate in a direction orthogonal to high information at both ends thereof is provided.

In addition, a first step of forming a step on the upper and lower surfaces of the base plate by the amount initially set to produce a switching shape and etching the adhesive groove;

In order to determine the thickness of the beam, impurity (boron, etc.) is penetrated onto the base plate to form the inner and outer thin film layers, and the second process of etching the lower middle portion to a certain depth in the etching solution to form the lower step. ;

A third step of partially etching the middle portion of the base plate by using the etch stop layer to obtain a mass and a rectangular thin film outside the mass;

Penetrating impurities such as boron to lower the resistance of the base substrate to form a conductive lower electrode, and thereafter removing the outer thin film layer;

A fifth step of obtaining an initial deformation by applying a thermal oxide film to the inner thin film layer by a difference in residual stress present in these thin film layers;

A sixth step of producing high information at both ends by etching a portion of the inner and outer thin film layers made of different materials;

A seventh step of forming an upper electrode on the upper surface of the mass and the high information at both ends;

A method of manufacturing a variable critical micro switch comprising an eighth step of aligning the high information at both ends and the upper and lower electrodes formed on the lower side of the mass body with the electrodes formed on the upper and lower flat glass, and then filling and bonding the adhesive to the adhesive groove. to provide.

Hereinafter, with reference to the accompanying drawings, preferred embodiments of the present invention that can specifically implement the above object will be described in detail.

1 to 3 are perspective views of the micro-switch according to the present invention, and longitudinal and lateral cross-sectional views thereof, with reference numeral 2 designating a base plate.

The base plate 2 is made of a silicon substrate, and the upper and lower portions of the central portion in the longitudinal direction are recessed with a predetermined width, so that the center portion is made of the small thickness portion 4 when viewed in cross section, and both sides thereof are large. It consists of thickness parts 6 and 8.

The small thickness portion 4 is formed with a rectangular space portion 10 at the center thereof, and adhesive grooves 12 and 14 recessed to a predetermined depth on the upper and lower sides of the large thickness portions 6 and 8. Is formed.

The long space portion 10 in the above is made of an inclined surface of the four sides are extended to the lower side.

On the outer surface of the base plate 2 as described above, the inner and outer thin film layers 16 and 18 having different residual stresses are overlapped, and at this time, the middle portion of the rectangular space portion 10 is cut in both longitudinal directions. Thus, both end fixing portions 22 are formed in a band shape, and a mass body 20 made of an inverted trapezoidal cube is attached and suspended at the central portion of the high information 22 at both ends thereof.

The high information 22 at both ends is made of the same material as the inner and outer thin film layers 16 and 18, and the suspended mass 20 has five surfaces that do not contact the high information 22 at both ends. It is the state apply | coated by the inner thin film layer 16, and the lower electrode 24 is formed in the lower surface.

A strip-shaped upper and lower adhesive electrodes 26 and 28 are formed on the upper and lower sides of the large thickness portions 6 and 8 between the small thickness portion 4 and the adhesive grooves 12 and 14, and are formed in the longitudinal direction. The upper electrode 30 is formed on the upper surface of the high information 22.

The upper electrode 30 has a rectangular wide portion 34 formed at both ends of the narrow portion 32 that accommodates the entire length of the high information 22 at both ends.

In addition, a strip-shaped glass electrodes 40 and 42 are formed on the lower surface of the central portion of the rectangular upper and lower glass 36 and 38 to cross the upper electrode 30 in the longitudinal direction. It has a configuration that is attached so that it can be located directly below.

When the upper and lower glasses 36 and 38 are bonded to the base plate 2 in the above, they are joined by a nutedic bonding or anodically bonding method.

Referring to the operation principle of the micro-switch of the present invention configured as described above is as follows.

For example, for the critical acceleration switch using the snap buckling of both ends of high information with initial deformation, as shown in FIG. 4, when the buckling analysis is performed by the both ends of high information with initial deformation, the lateral deformation of the high information of both ends rapidly occurs. Conditional expressions can be obtained.

Where (ω ₀ ) _max is sag at the center of the high information 22 at both ends, I is the beam cross-sectional moment of inertia, and A is the cross-sectional area of the beam.

In the case of a rectangular cross-beam having a thickness h of both ends high information 22, the above formula (I) is simplified as follows.

First, in order to fabricate a structure that satisfies the snap buckling buckling condition obtained in Equation (I), the position of the neutral axis in the composite layer including the inner and outer thin film layers 16 and 18 and the upper electrode 30 having different residual stresses. From this, we apply the linear elastic theory to find the initial deflection at the center.

Where M _σ is the moment generated from the difference in residual stress between the inner and outer thin film layers 16 and 18, and L is the length of the beam 22.

And the critical load for causing snap-through buckling is as follows.

In this case, the critical load causing the snap through buckling may be represented by the force of the electrostatic force due to the applied voltage between the electrodes and the inertia force due to the acceleration.

Here, the load due to the electrostatic force between the electrodes is expressed as follows.

Therefore, when the electrostatic force is adjusted by adjusting the voltage between the upper and lower electrodes 30 and 24 and the glass electrodes 40 and 42 of the both ends of the high information 22 having the initial deformation, both ends of the equation (V) It is possible to adjust the acceleration, i.e., the inertial force, necessary to cause the snap-through of the high information 22.

At this time, the switching phenomenon due to snap-through can be determined by the contact between the electrodes or the capacitance change between the electrodes.

In addition, it is possible to generate a snap-through phenomenon with only constant power in the absence of acceleration. By using these characteristics, voltage breakers, switches, relays, variable capacitors, micro-object fixing and alignment mechanisms, mechanical logic elements and gear elements are used. It is possible to do a self test to determine the performance of the switch itself.

In the above self test, when a voltage is applied between the electrode and the anode, the current flows while the electrode is in contact with the electrode by deforming at a constant voltage according to the length of the high information at both ends. In the case of a breakage, the snap-through phenomenon does not occur at a constant voltage, so that no current flows and a different current is detected and a problem is found in performance.

The performance test can be performed through this series of procedures.

Looking at the manufacturing process of the micro-switch of the present invention configured to operate as described above are as follows.

First, in the first step, as shown in FIG. 5 (a), in order to cause a switching phenomenon, the grooves 12 and 14 are etched while the steps are formed on the upper and lower surfaces of the base plate 2 by an amount initially set. .

In the second process, as shown in FIG. 5 (b), in order to determine the thickness of the beam, impurities (boron, etc.) are penetrated onto the base plate 2 to form inner and outer thin film layers 16 and 18. In order to form a lower step, the lower middle portion is etched to a certain depth in the etching solution.

In this case, the remaining inner and outer thin film layers 16 and 18 are removed and the remaining portion is used as an etch stop layer.

In the above, the inner thin film layer 16 is an etch stop layer, and the outer thin film layer 18 is made of a residual stress layer.

In the third process, as shown in FIG. 5 (c), the middle portion of the base plate 2 is partially etched using the etch stop layer to move the mass body 20 and the rectangular thin film 44 to the outside of the mass body 20. Get

In the fourth step, as shown in FIG. 5 (d), the lower electrode 24 is obtained. After removing the outer thin film layer 18, impurities such as boron are infiltrated to form conductive electrodes 24. do.

In the fifth step, as shown in FIG. 5 (e), by applying a thermal oxide film on the inner thin film layer 16, an initial deformation is obtained due to the difference in the residual stress present in these thin film layers.

In the sixth step, as shown in FIG. 5 (f), portions of the inner and outer thin film layers 16 and 18 made of different materials are etched to produce high information 22 at both ends.

In the seventh step, as shown in FIG. 5 (g), the upper electrode 30 is formed on the upper surface of the mass 20 and the high information 22 at both ends.

In the eighth process, as shown in FIG. 5 (h), the upper and lower electrodes 30 and 24 and the upper and lower plate glass 36 and 38 formed below the high information 22 and the mass 20 at both ends. After aligning the electrodes 40 and 42 formed on the adhesive grooves 12 and 14, the adhesive is filled and bonded to complete the manufacture of the micro switch.

6 shows the results of measuring the flow of current according to the applied voltage to the upper electrode 30 and the glass electrode 40 in order to confirm the operation of the switch manufactured as described above, and FIG. In the case where a 7 μg mass body 20 is formed in the center of the information 22, the voltage between both electrodes of the upper electrode 30 and the glass electrode 40 is adjusted to adjust the high information at both ends of three different lengths. In order to show this possible threshold acceleration range, it is a graph showing the relationship between the voltage between electrodes and the threshold acceleration.

According to the micro switch of the present invention as described above, the following effects can be obtained structurally.

First, it is possible to obtain the desired initial deformation by constructing the high information at both ends with inner and outer thin film layers having different residual stresses, and to adjust the voltage between the upper and lower electrodes and the upper and lower glass electrodes of the high information at both ends. Can be adjusted independently.

Second, the switch can be initialized to its original state by applying a voltage between the upper and lower electrodes and the upper and lower glass electrodes of the high information at both ends after the switch is operated, and can be used repeatedly after the switch is operated. It can be used as voltage breaker, switch, relay, etc., because it can connect high information at both ends of initial deformation only by voltage.

In addition, the effect of the characteristics of the manufacturing process

First, by simultaneously producing the micro switch spring beam and mass body integrally with the same flat material using semiconductor micromachining process, it is possible to simplify the assembly process and produce high information at both ends with thin film layers having different residual stresses. Thus, it is possible to use a variety of different thin films, it is possible to obtain the initial deformation of the desired size by adjusting the residual stress difference between the thin films.

Second, by using the thickness of the beam so that the etching can not proceed anymore, manufacturing errors that can occur in the manufacturing process can be reduced, and the residual stress due to impurity penetration can be used simultaneously for the initial deformation of the beam.

Third, since the gap for the switching phenomenon and the adhesive groove are manufactured at the same time, the efficiency of the process is increased, and by using the upper and lower glass, the parasitic capacitance is minimized and the upper and lower alignments are easily fixed.

Claims (10)

It is made of a silicon substrate, and the upper and lower portions of the longitudinal center portion are recessed with a predetermined width, so that the center portion is made of a small thickness portion in the cross section, and both portions are formed of a large thickness portion, and a space portion is formed in the center portion. A base plate; An inner and an outer thin film layer which is double coated on a portion of the base plate except for the lower side of the base plate, and is formed on the upper side of the space portion so that both sides in the longitudinal direction thereof are cut to form high information at both ends; A mass body attached to an intermediate portion of the high information at both ends and suspended; Upper and lower electrodes formed on both ends of the high information and the mass; Adhesive upper and lower electrodes formed on upper and lower surfaces of both base portions of the base plate; A band-shaped electrode is formed on one surface, and the variable critical micro switch comprising upper and lower glass attached to the upper and lower surfaces of the base plate in a direction orthogonal to the high information at both ends. The variable threshold micro switch according to claim 1, wherein the space portion is formed of an inclined surface in which four sides thereof extend downward. The variable critical micro switch of claim 1, wherein the mass is formed of an inverted cube. The variable critical micro switch of claim 1, wherein the upper electrode has a rectangular wide portion formed at both ends of the narrow portion accommodating the entire length of the high information at both ends. The variable threshold micro switch of claim 1, wherein the lower electrode is formed on its lower surface in a state in which five surfaces that do not contact the high information at both ends of the mass are applied by the inner thin film layer. The variable critical micro switch of claim 1, wherein the upper and lower glasses are bonded by an adhesive filled in an adhesive groove formed on upper and lower surfaces of a large thickness of the base plate. The variable threshold micro switch of claim 1, wherein both ends of the fixed beam are formed to have a self-diagnostic function by causing a snap through phenomenon by a voltage applied to the upper electrode and the upper glass electrode. The variable critical micro switch of claim 1, wherein the fixed beams at both ends are configured to undergo initial deformation so that switching and capacitance changes can be made while deforming only voltage between electrodes in a state where acceleration is not applied. Forming a step on the top and bottom surfaces of the base plate by an amount initially set to cause a switching phenomenon; In order to determine the thickness of the beam, impurity (boron, etc.) is penetrated onto the base plate to form the inner and outer thin film layers, and the second process of etching the lower middle portion to a certain depth in the etching solution to form the lower step. ; A third step of partially etching the middle portion of the base plate using the etch stop layer to obtain a mass and an etch thin film on the outside of the mass; Penetrating impurities such as boron to lower the resistance of the base substrate to form a conductive lower electrode, and thereafter removing the outer thin film layer; A fifth step of obtaining an initial deformation by applying a thermal oxide film to the inner thin film layer by a difference in residual stress present in the thin film layer; A sixth step of producing high information at both ends by etching a portion of the inner and outer thin film layers made of different materials; A seventh step of forming an upper electrode on the upper surface of the mass and the high information at both ends; A method of manufacturing a variable critical micro switch comprising an eighth step of aligning the high information at both ends and the upper and lower electrodes formed on the lower side of the mass body with the electrodes formed on the upper and lower flat glass, and then filling and bonding the adhesive to the adhesive groove. The method of manufacturing a variable critical micro switch according to claim 9, wherein in the first step, the adhesive grooves are etched on both sides of the base plate, and the upper and lower glass can be bonded by the adhesive filled therein.