JP4391076B2 - Microactuator with holding mechanism and method for manufacturing the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
[0002]
The present invention is an actuator that is provided on a semiconductor substrate and performs minute mechanical movements, and is capable of holding an operating part at a predetermined position without problems such as fluctuations, and a manufacturing method thereof. About.
[Prior art]
[0003]
Attempts have been made in various ways to provide an actuator that realizes minute movements on a semiconductor substrate by means of electrostatic force, electromagnetic force, thermal stress, etc., using a semiconductor microfabrication technique. In some cases, acceleration sensors, optical switches, and the like using this actuator have been put into practical use.
[0004]
An example of a typical actuator is a comb drive actuator (US Patent 5025346). In this comb drive actuator, electrodes are arranged in a comb field, one of the opposing comb fields is a fixed electrode and the other is a working electrode, and the working electrode is supported by a spring. When a voltage is applied to the comb electrode, the working comb electrode moves to a position balanced with the spring by electrostatic attraction. An example in which this comb drive actuator is applied to an optical switch has been reported.
[0005]
An example of an optical switch that uses the same electrostatic force, although not comb-like, has been announced. An electrostatic force is generated by applying a voltage between the upper electrode supported by the spring and the lower fixed electrode, and the upper electrode moves up and down. An optical switch that has an operating part on the upper electrode side and moves the operating part to a position that does not reflect the light beam by this up and down movement and switches the optical path of the light has been announced.
[0006]
An electrostatic force actuator called a scratch drive actuator has also been reported. In this scratch drive actuator, a silicon nitride film is formed as an insulating layer on a silicon wafer, and a plate with protrusions called bushings is disposed thereon. When a voltage is applied between the plate and the silicon wafer, the plate is attracted to the silicon wafer side by electrostatic attraction, and the bushing attached to the plate adheres to the silicon nitride film obliquely. When the voltage is removed, the plate is peeled off from the silicon nitride film. At this time, the bushing scratches the silicon nitride film, and the plate itself advances by the frictional force. That is, it is called a scratch actuator because it moves while scratching (scratching) the insulating film.
[0007]
In addition to these, various forms such as those using thermal stress and actuators using piezoelectric element films have been reported.
In addition, as an electromagnetic force actuator, for example, a type in which a coil is formed in an operating part, a magnetic field is generated by passing an electric current through the coil, and the operating part is moved by an electromagnetic force with a permanent magnet placed outside is reported. Has been.
[0008]
[Patent Document 1]
US patent 5025346
[Non-Patent Document 1]
Journal of Lightwave Technology, vol.17, No.1, January, p.2-6
[Non-Patent Document 2]
Journal of Microelectromechanical Systems, Vol.2, No.3 September 1993 p106-119
[Problems to be solved by the invention]
[0009]
However, the above-described conventional micro actuator has the following problems.
The first problem is that it is difficult to fix the operating part at a fixed position by vibration or the like.
[0010]
For example, in the above-mentioned comb drive actuator, when a voltage is applied between the opposing comb fields, it moves to the balance position between the electrostatic force and the spring due to the voltage, but this position does not vibrate even if the voltage is kept constant. When it is added, it will fluctuate. This fluctuation amount is calculated from the resonance frequency determined by the strength of the spring and the mass of the moving part. If the spring is weak, the resonance frequency becomes small, and even when slight vibration is applied, a fluctuation of several μm to several tens of μm occurs. In many cases, a micro actuator is designed to achieve a movement amount of several tens of μm, and fluctuation due to vibration reaches several tens of percent with respect to the movement amount of the design, which is a serious problem in practical use.
[0011]
On the other hand, when the spring is strengthened, the resonance frequency increases and the fluctuation amount due to vibration decreases, but in this case, a large amount of electric power is required to achieve a predetermined movement amount. Specifically, in the case of electrostatic force, there are cases where the applied voltage must be several hundred volts. When a high voltage is applied to a minute space, there is a high risk that the actuator will be destroyed by electric discharge.
[0012]
For example, in the case of air, the discharge start voltage is set to about 300 volts, and it is difficult to secure a moving amount corresponding to a strong spring without any risk of discharge. Therefore, it is very difficult to eliminate the fluctuation in the comb drive actuator regardless of which method is used.
[0013]
The fluctuation caused by the vibration is not limited to the electrostatic force, but the same problem occurs even when other driving force such as electromagnetic force is used. In other words, this is an unavoidable problem in the case of an actuator of the type that maintains the position in balance between the driving force and the spring.
[0014]
In addition, in the case of the above-described scratch drive actuator, this vibration problem can be avoided, but as the name suggests, the insulating film is scratched, so that the insulating film wears out and breaks if it is moved many times. Have another big problem.
[0015]
The second problem is that voltage and current must be continuously applied in order to stop the operating unit after moving the operating unit to a predetermined movement amount. Therefore, when the power is turned off, there is a problem that it cannot be stopped at that position and returns to the original position.
[0016]
Therefore, in order to stop the micro actuator at that position after moving the micro actuator by a predetermined amount, for example, a method of mechanically pressing it down is conceivable. However, in this case, an additional actuator that mechanically presses down is required, and the function of pressing down this actuator is lost when the power is turned off, so that the operating part returns to the original position. Therefore, in any case, it does not function as a fixing mechanism that does not depend on the power source.
[0017]
Although it is conceivable to electrostatically attract the operating part to the fixed part by electrostatic force, this method also cannot be electrostatically attracted when the power is turned off, and does not become a fixing mechanism independent of the power source.
[0018]
Therefore, by any method, when the power is turned off, the position of the operating unit cannot be held, and there is a problem of returning to the original position. Therefore, it is necessary to always turn on the power supply in order to maintain the position. When a large number of microactuators are used, a problem of consuming a large amount of power occurs. For example, if one microactuator is used for each wavelength in a DWDM communication system, 100 or more microactuators are required, and the power consumed to maintain the position is enormous.
[0019]
Also, if the power is turned off due to a power failure or the like, the micro actuator cannot hold its position, which is a big problem even in terms of safety. In order to prevent this, it is necessary to provide a backup power source or the like, which causes a problem in terms of cost.
[0020]
Accordingly, an object of the present invention is to solve the above-described conventional problems, and to provide a microactuator in which an operating part is fixed at a predetermined position without fluctuation, and is held at that position even when the power is turned off. There is to do.
[Means for solving the problems]
This inventor repeated earnest research in order to solve the conventional problem mentioned above. As a result, the inventors have found a micro actuator provided with a holding mechanism as described below and a manufacturing method thereof.
[0021]
In the microactuator having the holding mechanism of the present invention, a charged body made of polysilicon or the like is fixed on a transistor through an insulating film having a thickness that allows a tunnel current to flow through semiconductor micromachining. The transistor-side half surface of the charged body is also covered with an insulating film having a thickness that does not cause a tunnel current but does not reduce the capacitance. Furthermore, an operating part is arranged at a position away from the charged body.
[0022]
Here, the tunnel current is a current that flows due to a tunnel effect in which electrons having high energy (Hot Electron) pass through an insulating film having a predetermined thin film thickness.
[0023]
Use a method such as electrostatic attraction to move the moving part to a charged body (actually covering insulating layer) Contact position Move up. Next, charges are accumulated in the charged body by a tunnel current from the channel portion of the transistor. Even if the power is turned off, the electric charge remains accumulated, so that the position of the operating part continues to be held by the electrostatic attraction generated between the charged body and the operating part due to the electric charge.
In addition, the microactuator of the present invention is not a mechanism that maintains the position by balancing the force of electrostatic attraction and the like with a spring or the like, so that problems such as position fluctuations due to vibration and the like do not occur.
[0024]
According to a first aspect of the microactuator having a holding mechanism of the present invention, a transistor having a source terminal, a drain terminal, and a channel on a surface layer portion, and a surface of the transistor including the channel from the channel. SiO film with a thickness of 10 to 100 nm that allows tunneling current to flow ₂ The film thickness is sufficient to prevent a tunnel current from flowing on the surface opposite to the surface in contact with the insulating film (5) and not to reduce the capacitance. 0.1 to 1 μm SiO ₂ At least one charged body comprising the insulating film (7), a pillar portion disposed on the transistor, and a plate portion disposed on the pillar portion in a manner insulated from the transistor via an insulating layer, And an operating portion disposed at a position 1 at a predetermined distance from the charged body by an urging force of the spring, and the plate extends from the position 1 to the insulating film ( 7) Touched Move to position 2, current flows through the channel, voltage is applied to the drain and the operating unit, and the charged body is charged by a tunnel current from the channel, and the charged body and the operating unit are charged by the charging. And a holding mechanism that holds the plate at the position 2 by an electrostatic attractive force that does not return to the position 1 by the biasing force of the spring.
[0025]
A second aspect of the microactuator provided with the holding mechanism according to the present invention is a microactuator provided with a holding mechanism in which the transistor is an NPN transistor.
[0026]
According to a third aspect of the microactuator having the holding mechanism of the present invention, the microactuator has a holding mechanism in which the operating part moves to the position 2 due to electrostatic attraction generated between the transistor and the operating part. Actuator.
[0027]
According to a fourth aspect of the microactuator provided with the holding mechanism of the present invention, the amount of charge to be charged to the charged body is controlled, Said plate It is a micro actuator provided with the holding mechanism which controls the amount of movements.
[0030]
Of the micro actuator provided with the holding mechanism of the present invention. Fifth aspect Is a micro actuator provided with a holding mechanism in which a control dielectric is further provided on the charged body.
[0032]
Embodiments of the present invention will be described in detail with reference to the drawings.
First, an overall description will be given of a micro actuator provided with a holding mechanism of the present invention.
[0033]
As described above, in the conventional micro actuator, the type that moves and holds the operating part by the balance of the force of the electrostatic force and the spring, as represented by the comb drive actuator, and the micro actuator such as the scratch drive actuator. There is an actuator. In the former case, there is a risk that the position of the operating part will fluctuate due to resonance. In the latter case, if the movement of the operating part is repeated many times, the insulating film will be worn out and broken.
[0034]
Furthermore, as a common problem with conventional micro actuators, when the power is turned off, the force that held the operating part in place disappears, and the operating part cannot be held in that position, and the original position There is a problem that will return to. Therefore, in order to hold the operating unit at the same position, it is necessary to keep the power on, and when a large number of micro actuators are used, there is a problem that a large amount of power is consumed.
[0035]
Therefore, as long as the micro actuator has a function capable of maintaining the state even when the power is turned off, such as a flash memory as a storage medium in a computer or a digital camera, an optical communication system and various other Can enjoy major technical and economic advantages in various fields.
[0036]
The micro actuator provided with the holding mechanism of the present invention is an invention that solves the above two problems and can be used in many applications.
Specifically, the present invention is an actuator having a transistor, a charged body, and an operating part as main members. The transistor includes a source terminal, a drain terminal, and a channel on a surface layer of a silicon substrate. For example, an NPN transistor is a typical example. Here, the channel is a current flow path between the source terminal and the drain terminal.
[0037]
The charged body is fixed to the surface of the transistor including the channel portion through an insulating thin film having a thickness of about several tens of nm so that a tunnel current flows from the channel. The opposite surface of the transistor of the charged body is thick enough to prevent the tunnel current from flowing, but it is an insulating thin film with a thickness of typically 0.1 μm to 1 μm that does not reduce the capacitance. Covered with. It is also possible to provide a plurality of charged bodies covered with this insulating film.
[0038]
Further, an operating unit is installed at a distance from the charged body fixed on the fixed electrode. The working part consists of a position away from the charged body, a charged body (in practice, a surface insulating film) Touched position Move between.
[0039]
Here, the operating part is changed to a charged body (implemented with an insulating film on the surface) by some method such as electrostatic attraction. Touched position Move to. For example, it is one method to move by the electrostatic attraction generated between the transistor and the operating part.
[0040]
Next, when electric charges are accumulated in the charged body from the channel by the tunnel current, the charged body attracts the operating part by electrostatic attraction and holds it in the contacted position. Therefore, since the position is not held in balance with the spring force as in the prior art, the position of the operating part does not change and the position is maintained. In addition, problems such as damage to the insulating film do not occur.
[0041]
In addition, since the electric charge stored in the charged body by the tunnel current is not erased semi-permanently, the electrostatic attraction is maintained even when the power is turned off. Adsorption can be stably maintained unless the step is performed.
[0042]
In addition, when it is desired to move the moving part to a different position, the charge of the charged body is once erased. Next, the operating unit can be moved to another position by some method such as electrostatic attraction, and then the position can be held by the same method as described above. In other words, the charge can be accumulated in the charged body in contact with the operating portion by the tunnel current, and the position can be held by the electrostatic attraction due to the charge.
[0043]
Here, FIG. 1 shows a first embodiment of a micro actuator provided with a holding mechanism of the present invention. In this embodiment, the plate of the operating part moves up and down by electrostatic attraction, and has a mechanism that moves between the position 1 of the initial position and the position 2 attracted by the electrostatic attraction.
[0044]
The silicon substrate forming the transistor 1 in FIG. 1A is P-type silicon doped (doped) with boron. In the upper surface layer portion of the silicon substrate, phosphorus is doped to form an NPN type transistor region, whereby the transistor 1 is obtained. In FIG. 1, the left N layer is the source terminal 2, and the right N layer is the drain terminal 3. The width of the channel 4 serving as a current flow path between the source terminal 2 and the drain terminal 3 is about 0.2 μm.
[0045]
In the central portion of the upper surface of the transistor 1 in FIG. ₂ The insulating film 5 is provided. The SiO ₂ On the insulating film 5, polysilicon having a thickness of about 0.3 μm is provided as the charging body 6. The planar size of the charged body 6 is 450 μm square. Next, SiO having a film thickness of about 0.5 μm is formed on the charged body 6. ₂ An insulating film 7 is provided.
[0046]
Further, on the transistor 1, an operating part 8 composed of a plate 9 and a spring 10 and a structure 13 having two column parts 11 as main members are installed. The two column portions 11 are installed at positions on both sides of the charging body 6.
The operating unit 8 is installed in the column portion 11 with the insulating layer 12 interposed therebetween, and is insulated from the transistor 1.
[0047]
Next, the operation of the micro actuator provided with this holding mechanism will be described.
First, the silicon substrate portion under the transistor 1 and the source 2 are grounded. A high voltage is applied to the operating portion 8 including the plate 9 and the spring 10 and the drain 3. Here, as described above, the operating unit 8 is electrically insulated from the transistor 1.
[0048]
By applying the above voltage, electrons run in the channel 4 region at high speed from the source 2 to the drain 3. Electrons (Hot Electrons) that obtain sufficiently high energy in the vicinity of the drain 3 are scattered by the silicon crystal lattice and injected into the charged body 6 by the tunnel effect at the interface of the insulating film 5. This current is called a tunnel current.
[0049]
Further, since electrostatic attraction acts between the transistor 1 and the upper plate 9, the plate 9 moves downward and is fixed in contact with the insulating film 7 on the upper side of the charging body 6. (See FIG. 2 (b).)
Even if the application of the voltage is stopped here, the electrostatic attraction acts between the plate 9 and the charged body 6 due to the electric charge accumulated in the charged body 6, and the plate 9 is fixed while being in contact with the insulating film 7. Will remain. The plate 9 does not return upward.
[0050]
As a result, the writing of the position information is completed. That is, even if the power is turned off, the position information is maintained, and the same function as the storage holding function of the flash memory used for the electronic device can be obtained.
[0051]
Next, a method for erasing this writing will be described. From the above state, the drain 3 is grounded, and the operating unit 8 is also grounded. The silicon substrate under the transistor 1 is left grounded. Here, when a high voltage is applied to the source 2, the electrons accumulated in the charged body 6 are pulled out to the drain 3 by the tunnel effect, and the charged body 6 returns to neutral. Accordingly, no electrostatic attractive force is generated between the charged body 6 and the plate 9, so that the plate 9 returns to the original upper position by the force of the spring 10. That is, the position information has been erased.
[0052]
In this embodiment, the memory function is realized in which the plate is moved to the upper and lower two positions and the position is maintained even when the power is turned off, but it may be in other directions. It is also possible to have a mechanism that has a plurality of charged bodies and can take a plurality of positions. A micro actuator that can provide such a holding function has not been realized in the past.
[0053]
Next, the manufacturing method of the micro actuator provided with the holding mechanism of this invention is demonstrated. An embodiment of the method for manufacturing the micro actuator shown in the first embodiment will be described with reference to FIG.
[0054]
On the silicon substrate 31, a pattern to be an NPN transistor is photoresisted and phosphorus ions are implanted. In this step, an NPN transistor is manufactured. (See FIGS. 2 (a) and (b).)
Here, the photoresist is to form a pattern with a polymer resin by utilizing the difference in solubility in the developer between the irradiated part and the unirradiated part. Phosphorus is not driven into the portion covered with the polymer resin.
[0055]
Subsequently, only a predetermined area in which the insulating film 32 is generated is opened with a photoresist, and the silicon substrate 1 is thermally oxidized together with the silicon substrate 1 in the above area. ₂ An oxide film is formed and an insulating film 32 is provided. In this embodiment, the thickness of the insulating film 32 is 70 nm. (See FIG. 2 (c).)
[0056]
Subsequently, an opening in an area smaller than the area of the insulating film 32 is formed by a photoresist, and a polysilicon film having a thickness of about 0.3 μm is generated in the opening by a low pressure CVD (LPCVD) method. 33 is provided. (See FIG. 2 (d).)
[0057]
Subsequently, an opening is made in the same area as the insulating film 32 with a photoresist, and a SiO film having a thickness of about 0.5 μm is formed by a CVD method. ₂ A film is generated and an insulating film 34 is provided. (See FIG. 2 (e).)
As described above, a fixed portion in which a charged body having an insulating film is fixed to the transistor is manufactured.
[0058]
Next, as another silicon substrate, an active part is manufactured using a two-layer SOI (Silicon-On-Insulator) plate (see FIG. 2F) having an active layer thickness of 2 μm and 25 μm. Here, the SOI plate is a silicon substrate formed by growing a single crystal silicon thin film on an insulating substrate.
On the 2 μm active layer of this SOI plate, a pattern of the plate 35 and the spring 36 is drawn by opening a portion to be removed with a photoresist. Next, the opening of the photoresist is etched vertically by an ICP (Inductively Coupled Plasma) etching apparatus until it reaches the insulating layer of the SOI plate. (See FIG. 2 (g).)
[0059]
Subsequently, from the back side (25 μm active layer side) of the SOI plate, an area slightly larger than that corresponding to the position of the plate 35 and the spring 36 is etched vertically until reaching the insulating layer with an IPC etching apparatus, A column portion 37 is provided. (See FIG. 2 (h).)
[0060]
Subsequently, when unnecessary portions of the insulating layer 39 are melted with a solvent, a structure 38 is obtained in which the plate 35 is supported by the spring 36 and floats in the air. (See Fig. 2 (i).)
[0061]
A microactuator having the holding mechanism of the present invention is manufactured by fusing the structure 38 obtained above and the transistor (fixed portion) shown in FIG. (See FIG. 2 (j).)
[0062]
By the manufacturing method as described above, it is possible to stably manufacture a micro actuator provided with the holding mechanism of the present invention without increasing the manufacturing cost.
[0063]
Next, Embodiment 2 of the present invention is shown in FIG.
In the second embodiment, a control dielectric is further provided on the dielectric shown in the first embodiment.
[0064]
Further, in Example 1, the operating part moved up and down and moved between position 1 and position 2, but in this example, an operating part supported by a rotating hinge is provided, and the operating part is connected to the fixed electrode. It rotates due to electrostatic attraction generated between them. That is, the operating unit has a mechanism that rotates between the initial position 1 and the position 2 rotated a predetermined angle from the position 1.
However, as in the first embodiment, it is of course possible to use a type in which the operating part moves up and down.
[0065]
3A and 3B show the structure on the fixed electrode side. FIG.3 (b) shows sectional drawing in the arrow A shown to Fig.3 (a). The silicon substrate on which the transistor 1 is formed is P-type silicon to which boron is added (doped), as in the first embodiment. The upper surface layer portion of this silicon substrate is doped with phosphorus to form an NPN type transistor region, thereby forming the transistor 1. In FIG. 3B, the left N layer is the source terminal 2, and the right N layer is the drain terminal 3.
[0066]
Similar to the first embodiment, the upper surface of the transistor 1 is made of an insulating film 5 having a thickness of about 70 nm and polysilicon having a thickness of about 0.3 μm covered with an insulating film 7 having a thickness of about 0.5 μm. A dielectric 6 is provided in the region shown in FIG. In the present embodiment, an area larger than that of the first embodiment is taken so that sufficient electrostatic attractive force can be obtained.
[0067]
A control dielectric 40 made of polysilicon is provided at a position where the upper surface of the insulating film 7 covers the NPN transistor. In the embodiment of FIG. 3, the polysilicon dimensions are about 5 μm thick and about 5 μm wide.
[0068]
Further, as shown in FIG. 3C, a structure 13 made of an SOI plate is anodically bonded onto the fixed electrode. The structure 13 is provided with an operating part 42 supported by a rotary hinge 41. Similar to the first embodiment, the rotary hinge 41 and the operating portion 42 are insulated from the lower portion of the structure 13 and the fixed electrode by the insulating layer of the SOI plate.
[0069]
Here, the operation of the second embodiment will be described. First, the silicon substrate portion under the transistor 1 and the source 2 are grounded. Further, the rotary hinge 41 and the operating unit 42 are also grounded. Next, a high voltage is applied to the drain 3 and the control dielectric 40.
[0070]
By this voltage application, electrons run in the channel region 5 from the source 2 toward the drain 3 at a high speed. Electrons (hot-electrons) that obtain sufficiently high energy in the vicinity of the drain 3 are scattered by the silicon crystal lattice and injected into the dielectric 6 by the tunnel effect at the interface of the insulating film 6.
An electrostatic attractive force acts between the dielectric 6 charged by the injected electric charge and the operating portion 42, and the operating portion 42 rotates around the rotary hinge 41 as a rotation axis as shown in FIG. It reaches. This rotation angle can be controlled by the amount of charge injected into the dielectric 6. The amount of charge injected can be controlled by controlling the magnitude and time of the applied voltage.
[0071]
Even if the application of the voltage is stopped, the electric charge accumulated in the charged body 6 is covered with the insulating films 5 and 7 so that it does not escape. Therefore, the electrostatic attractive force with the operating part 42 is maintained semipermanently. to continue.
That is, by controlling the amount of charge injected into the charged body 6, the position information of the operating unit 42 can be written and held at an arbitrary rotation angle.
[0072]
Next, a method for erasing this position information is shown. From the above state, the drain 3 is opened, and the control dielectric 40 and the silicon substrate portion under the transistor 1 are grounded. Here, when a high voltage is applied to the source 2, electrons in the dielectric 6 are pulled out to the drain 3 by the tunnel effect, and the dielectric 6 returns to neutral.
Since there is no electrostatic attraction between the dielectric 6 and the operating part 42, the operating part 42 returns to the original position 1 by the spring force of the rotary hinge 41. That is, the position information is erased.
[0073]
Here, the manufacturing method of the micro actuator provided with the holding mechanism of Example 2 will be briefly described.
The method of providing the dielectric 6 made of polysilicon covered with the insulating film 5 and the insulating film 7 on the transistor 1 having the NPN transistor structure on the fixed electrode side is the same as that of the first embodiment.
Further, an opening is provided on the insulating film 7 at a predetermined position covering the NPN transistor portion with a photoresist. Then, the control dielectric 40 is provided by depositing polysilicon in this opening by the CVD method.
[0074]
Next, a method for manufacturing the structure 13 on the operating part side, the rotary hinge 41, and the operating part 42 will be described. Basically, this is the same as in Example 1, and a two-layer SOI plate having active layer thicknesses of 25 μm and 2 μm is used.
On the 2 μm active layer of this SOI plate, a pattern of the rotary hinge 41 and the working part 42 is drawn by opening a portion to be removed with a photoresist. Next, the opening of the photoresist is etched vertically by the ICP etching apparatus until it reaches the insulating layer of the SOI plate.
[0075]
Subsequently, from the back side of the SOI plate (25 μm active layer side), an area slightly larger than that corresponding to the position of the rotary hinge 41 and the working portion 42 is etched vertically until reaching the insulating layer with the IPC etching apparatus. The column portion 37 is provided. Subsequently, when an unnecessary portion of the insulating layer of the SOI plate is dissolved with a solvent, the structure 13 is obtained in which the operating portion 42 is supported by the rotary hinge 41 and floats in the hollow.
[0076]
As described above, also in the second embodiment, similarly to the first embodiment, it is possible to stably manufacture the microactuator having the holding mechanism of the present invention without increasing the manufacturing cost.
[0077]
Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various embodiments can be considered.
【The invention's effect】
[0078]
In the conventional micro actuator, when the operating part is held at a fixed position, there are problems that the position is fluctuated due to problems such as resonance due to a spring and that the insulating layer is damaged. However, in the micro actuator provided with the holding mechanism of the present invention, the operating part can be held at a fixed position without fluctuations, and problems such as damage to the insulating layer do not occur.
[0079]
Furthermore, since the conventional microactuator cannot hold the position of the operating part when the power is cut off, it has no function of holding the position information. However, in the microactuator provided with the holding mechanism of the present invention, the position of the operating part is held as it is even when the power is turned off. Therefore, the position information can be held for the first time in the microactuator.
Further, by controlling the voltage to be applied and the like, it is possible to control the amount of charge to be charged on the charged body, to control the movement amount of the operating part, and to hold the operating part at an arbitrary position.
[0080]
Furthermore, when using a conventional minute actuator, it must be used with the power turned on in order to maintain the position of the operating portion. Even if the power consumption of one microactuator is small, for example, if a microactuator is used for each wavelength of a DWDM communication system, 100 or more are required. As a whole, large power consumption is achieved simply by maintaining the position of the operating unit. It becomes.
However, in the present invention, in order to maintain the position of the operating part, no power is consumed,
That is, the power consumption occurs only when the stored information is rewritten, and no power consumption occurs when the stored information is stored. Therefore, the operating cost of the system is greatly reduced. Therefore, there is a great economic advantage.
[0081]
Furthermore, in the case of the conventional minute actuator, there is a risk that the held information cannot be maintained when the power source holding the operating part is cut off due to a power failure or the like. Further, in order to prevent this, an extra cost such as a backup power source is required.
However, in the present invention, even if the power cut off due to a power failure or the like occurs, the retention of the position information is not affected at all. Therefore, a highly safe system can be constructed.
[0082]
Furthermore, according to the manufacturing method of the present invention, a microactuator having a holding mechanism can be manufactured stably at a low manufacturing cost, so that it can be expected to be widely applied to the above-described DWDM communication system.
[Brief description of the drawings]
FIG. 1 is a diagram showing the structure and operation of a first embodiment of a micro actuator provided with a holding mechanism of the present invention.
FIG. 2 is a view showing a manufacturing method of a micro actuator provided with a holding mechanism of the present invention.
FIG. 3 is a diagram showing the structure and operation of a second embodiment of a micro actuator provided with a holding mechanism of the present invention.
[Explanation of symbols]
1 transistor
2 Source terminal
3 Drain terminal
4 channels
5 Insulating film
6 Charged body
7 Insulating film
8 working parts
9 boards
10 Spring
11 Pillar part
12 Insulation layer
13 Structure
21 transistor
22 Charged body
23 Transistor
24 Charged body
25 boards
26 Spring
27 Working parts
28 Structure
31 Silicon substrate
32 Insulating film
33 Charged body
34 Insulating film
35 boards
36 Spring
37 pillars
38 Structure
39 Insulating layer
40 Charged body for control
41 Rotating hinge
42 Working parts

Claims (5)

A transistor having a source terminal, a drain terminal, and a channel in a surface layer portion;
The surface of the transistor including the channel is fixed via a SiO ₂ insulating film (5) having a thickness of 10 to 100 nm so that a tunnel current from the channel flows, and is opposite to the surface in contact with the insulating film (5). And at least one charged body provided with a SiO ₂ insulating film (7) having a film thickness of 0.1 to 1 μm which is sufficient to prevent a tunnel current from flowing and does not reduce the capacitance;
A pillar portion installed on the transistor;
The column portion is installed in a manner insulated from the transistor through an insulating layer, and is composed of a plate and a spring, and the plate is placed at a position 1 at a predetermined distance from the charged body by the biasing force of the spring. Arranged operating parts;
With
The plate moves from the position 1 to a position 2 in contact with the insulating film (7);
A current is passed through the channel, a voltage is applied to the drain and the working part, and the charged body is charged by a tunnel current from the channel,
A holding mechanism in which the plate is held at the position 2 by an electrostatic attractive force that is generated between the charged body and the operating portion due to the charging and does not return to the position 1 by the biasing force of the spring. With micro actuator.   The microactuator provided with a holding mechanism according to claim 1, wherein the transistor is an NPN transistor.   The microactuator provided with the holding mechanism according to claim 1 or 2, wherein the operating part moves from the position 1 to the position 2 by an electrostatic attractive force generated between the transistor and the operating part.   The micro actuator provided with the holding mechanism according to claim 3, wherein the amount of movement of the plate is controlled by controlling the amount of charge to be charged to the charged body.   The micro actuator provided with the holding mechanism according to any one of claims 1 to 4, wherein a control dielectric is further provided on the charged body.

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