JPH0621532A - Microscopic rotating mechanism - Google Patents

Abstract

PURPOSE:To obtain a microscopic rotating mechanism of a structure, wherein a rotator does never make a frictional contact with a rotating shaft not only in the axial direction but also in the radial direction at the time of stable rotation of the rotator and a loss of rotation can be significantly reduced. CONSTITUTION:A microscopic rotating mechanism, which has a rotating shaft 2 on a substrate 4 and is rotated by a rotator 1, is a microscopic rotating mechanism of a structure, wherein the line of intersection of the surface, which opposes to the rotator 1, of this rotating shaft 2 with the plane including the central axis of the rotating shaft 2 is formed obliquely to this central axis.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a micro rotating mechanism belonging to the field of so-called micromachines.

[0002]

2. Description of the Related Art In recent years, micromachines, which mean ultra-small machines, have come to be verbally used not only in universities and academic societies but also in industry. Micromachines, which have been actively researched mainly by semiconductor researchers in the United States, aim to create micro-sized mechatronic systems by simultaneously producing mechanical elements such as actuators and gears and electronic elements such as sensors and arithmetic and control circuits. Is. This theme is a dream for researchers in many fields beyond electronics. In particular, this is a field where the distance between physical property research, including functional materials, and applied research is closer than ever.

As one of those belonging to the field of micromachines, there is a minute rotation mechanism. This is achieved by making full use of a movable mechanism element formed on a substrate such as silicon, that is, pattern formation by a photolithography technique which is a semiconductor manufacturing process, thin film formation by a CVD method, selective etching, etc. on a substrate such as silicon. The rotary shaft and the rotor are manufactured.

FIG. 5 and FIG. 6 show an example of this minute rotation mechanism. Here, the one having eight protrusions at the center of FIG. 5 is a rotor 1 made of polycrystalline silicon (polysilicon), which surrounds it.
The two protrusions are the stator 7. The rotor 1 is rotatably arranged with respect to a rotary shaft 2 having a stopper at the top for preventing the rotor 1 from jumping out.

When a voltage is applied to the above-mentioned stator, the opposite electric charges approach the outer side of the rotor 1 and gather, so that the stator 7 and the rotor 1 attract each other. When this voltage is used as an alternating current and the voltage of the stator 7 is sequentially changed so that the rotor 1 is attracted to the next stator 7 to rotate. The above is the driving principle.

Next, a method of manufacturing this minute rotation mechanism will be described with reference to FIG.
~ It demonstrates concretely using FIG. First,
As shown in FIG. 7A, the substrate 4 made of Si is replaced with O ₂ or H ₂
When heated to a high temperature in the oxidizing atmosphere of O, the oxide film SiO ₂
The layer is formed on the substrate 4. Next, a photoresist 8 which is a polymer material is applied onto SiO ₂ (FIG. 7B). next,
The photoresist is exposed according to the pattern using the exposure mask 5 (FIG. 7C). Next, extra photoresist 8
Are removed by washing (FIG. 8A). Next, an exposed HF solution is used to dissolve only the exposed SiO ₂ layer, and the resist 8
The substrate 4 is not attacked (FIG. 8B). Next, the resist 8 is removed using an organic solvent (FIG. 8C). Next, a polysilicon (Poly Si) layer to be the rotor 1 is formed on the SiO ₂ layer of the PSG layer (first layer) by the CVD (Chemical Vapor Deposition) method. That is, the polysilicon layer (second layer) shown in FIG. 9A. Here, the SiO ₂ layer to be removed is referred to as PSG (sacrificial layer) because it is removed at the time of completion. next,
As a pre-process for forming the rotary shaft 2, SiO _{2 is} again used.
The layer is formed by the CVD method. That is, it is the PSG layer (third layer) made of the SiO ₂ layer shown in FIG. 9B. next,
A polysilicon layer to be the rotating shaft 2 is formed by CVD. That is, the polysilicon layer (fourth layer) shown in FIG. 9C.
Is. Finally, as shown in FIG. 9D, the fine rotation mechanism is completed by removing only the SiO ₂ layer using the HF aqueous solution again.

[0007]

However, in the above-described conventional micro-rotation mechanism, since the size of the component itself is very small, it is not possible to provide a component such as a rolling bearing for smooth rotation.

Further, since oil and grease cannot be used because the viscosity loss becomes large, the friction between the rotor 1 and the substrate 4 or the rotary shaft 2 is large and the life of the minute rotating mechanism itself is shortened. There was a problem that it would end up.

In particular, the operating mechanism applying the semiconductor process is planar and it is difficult to adopt a thick three-dimensional structure. Therefore, friction and wear of the rotor 1 with respect to the rotating shaft 2 in the radial direction are not so great. There were problems such as not being considered.

The present invention has been made in view of the above problems, and during stable rotation of the rotor, the rotor does not make frictional contact with the rotating shaft not only in the axial direction but also in the radial direction. The object is to obtain a minute rotation mechanism capable of significantly reducing rotation loss.

[0011]

As shown in FIG. 1, for example, the fine rotation mechanism of the present invention has a rotation shaft 2 on a substrate 4 and is rotated by a rotor 1. The line of intersection between the surface of the rotor 2 facing the rotor 1 and the plane including the central axis of the rotary shaft 2 is oblique with respect to the central axis.

Further, the minute rotation mechanism of the present invention comprises a rotary shaft 2
The surface opposite to the rotor 1 has a groove having a groove. Further, the micro-rotation mechanism of the present invention is the micro-rotation mechanism having the above-mentioned configuration in which the groove has a fishbone shape.

[0013]

According to the minute rotation mechanism of the present invention, in the minute rotation mechanism having the rotating shaft 2 on the substrate 4 and rotated by the rotor 1, the surface of the rotating shaft 2 facing the rotor 1 and the rotating surface are rotated. The line of intersection with the plane including the central axis of the shaft 2 is inclined with respect to the central axis so that the inclined portion 2a of the rotary shaft 2 and the rotor 1 produce a dynamic pressure effect. Therefore, during stable rotation, the rotary shaft 2 and the rotor 1 do not make frictional contact, and this is effective not only in the axial direction but also in the radial direction, which has not been considered so far in the past, and the remaining thickness is increased. Even in the case of no structure, the rotation loss can be greatly reduced.

Further, according to the minute rotation mechanism of the present invention, the surface of the rotation shaft 2 facing the rotor 1 has a groove, and the surface of the rotation shaft 2 has a groove. By generating the dynamic pressure effect by the groove pattern and receiving both the radial direction and the axial direction of the rotor 1 by the air film, the rotation loss can be reduced.

Further, according to the minute rotation mechanism of the present invention, the groove has the fishbone shape and the minute rotation mechanism having the above-mentioned configuration is provided. A uniform high dynamic pressure effect is generated, the radial direction of the rotor 1,
By receiving the air film in both axial directions, the rotation loss can be reduced.

[0016]

【Example】

An embodiment of the minute rotation mechanism of the present invention will be described below with reference to FIGS. 1 to 3 together with a manufacturing method.

First, as shown in FIG. 2A, the substrate 4 is etched so as to form a part of a conical shape, and the inclined portion 2a is formed.
To make. Then, a fishbone-shaped groove pattern as shown in FIG. 4 is formed on the inclined portion 2a of the substrate 4 by photolithography (FIG. 2B).

Next, the SiO ₂ layer 4a is formed on the substrate 4 by CVD.
Formed (FIG. 2C). Next, this SiO ₂ layer 4a
Polysilicon to be the rotor 1 is formed on the top by CVD (FIG. 2D). Next, a SiO ₂ film 4b is formed on the polysilicon layer 1 by CVD as a pre-process for forming the rotating shaft 2 (FIG. 3A).

Next, the inclined portion 2a forming a part of a conical shape
Polysilicon to be the rotating shaft 2 is formed on the upper surface by CVD (FIG. 3B). Here, the rotating shaft 2 holds the rotor 1, and the rotating shaft 2 is continuous with the substrate 4 while maintaining a shape that conically expands from the middle to the lower part. The conical portion is in contact with the rotor 1. Further, a disc-shaped stopper is provided on the upper portion of the rotary shaft 2 so as to prevent the rotor 1 from coming off.

Finally, using a HF aqueous solution, all Si
The O ₂ layer is removed to complete the micro rotation mechanism of this example (Fig. 3).
C, Fig. 1)). Here, the rotor 1 is held by the rotary shaft 2 and rotates about the rotary shaft 2, and constitutes the central structure of the minute rotation mechanism of this embodiment. The inner peripheral surface (dynamic pressure bearing portion 1a) of the rotor 1 which comes into contact with the rotary shaft 2 has the same shape as the conical portion of the rotary shaft 2, and when the rotor 1 is stationary, the rotary shaft It comes into close contact with 2. Further, by setting the diameter of the dynamic pressure bearing portion 1a of the rotary shaft 2 in an appropriate range,
A certain gap is secured so that the lower surface of the rotor 1 does not come into contact with the upper surface of the substrate 4.

Here, as the method of forming the inclined portion 2a of the rotating shaft 2, in addition to the method of forming the substrate 4 by shaving the substrate 4 by anisotropic etching or the like, after the film is formed on the substrate 4 by the CVD method or the like. Alternatively, it can be formed by a manufacturing method. Also,
The upper portion of the rotary shaft 2 and the rotor 1 can be configured by making full use of film formation and selective etching as described above.

A groove pattern as shown in the example of FIG. 4 is formed on the inclined portion 2a of the rotary shaft 2 by making full use of pattern formation and etching by a photolithography technique, and rotation of the rotor 1 produces a dynamic pressure effect. The air film is generated in. The groove pattern is not limited to the fishbone shape shown in FIG. 4, but a spiral shape or the like can exert the dynamic pressure effect.

Further, as can be seen from FIG. 1, in the stationary state, the rotor 1 is not in contact with the substrate 4 but only with the inclined portion 2a of the rotating shaft 2, so that 6 of the conventional example (the rotor 1 and the substrate 4 are not in contact with each other according to the drawing, but the entire bottom surface of the rotor 1 is in contact with the upper surface of the substrate 4 when the rotor is stationary). Than child one
The contact area is small, and it is possible to prevent stiction, which is a phenomenon in which the rotor 1 sticks and becomes inoperable. Further, the present example is effective not only for the rotating portion of the motor but also for the rotating mechanism such as the gear that is the power transmission means.

As described above, according to this example, in the minute rotation mechanism having the rotating shaft 2 on the substrate 4 and rotated by the rotor 1, the surface of the rotating shaft 2 facing the rotor 1 is: The line of intersection with the plane including the central axis of the rotary shaft 2 is assumed to be inclined with respect to this central axis.
Since the dynamic pressure effect is generated by the inclined portion 2a and the rotor 1, the rotary shaft 2 and the rotor 1 do not make frictional contact during stable rotation. The effect also appears in the radial direction, which should not be taken into consideration, and the rotation loss can be greatly reduced even in a structure with little thickness. Also, as a secondary effect,
Due to the configuration, when stationary, the rotating shaft 2 and the rotor 1 are
Since it comes into contact only at a,
Since the contact area is quite small, stiction can be prevented. Further, in carrying out this example, since it can be manufactured by applying the conventional semiconductor manufacturing process, mass production is possible.

Further, according to this example, the rotor 1 of the rotary shaft 2 is
By using the minute rotation mechanism having the above-mentioned configuration in which the surface opposite to the groove has a groove, a dynamic pressure effect due to the groove pattern is further generated in addition to the above-mentioned effect, and the rotor 1 is rotated in both radial and axial directions. The rotation loss can be reduced by receiving the air film.

Further, according to the present embodiment, the groove has the fishbone shape, and the fine rotation mechanism having the above-mentioned configuration is employed. The dynamic loss effect can be generated, and both the radial direction and the axial direction of the rotor 1 can be received by the air film to reduce the rotation loss.

The present invention is not limited to the above-mentioned embodiments, and it goes without saying that various other configurations can be adopted without departing from the gist of the present invention.

[0029]

As described above, according to the present invention,
Since the dynamic pressure effect is generated by the inclined portion 2a of the rotary shaft 2 and the rotor 1, the rotary shaft 2 and the rotor 1 are
There is no frictional contact, and this has an effect not only in the axial direction but also in the radial direction, which has not been considered so far in the past, and it significantly reduces the rotation loss even in the structure with little thickness. A dynamic pressure effect due to the pattern is generated, and both the radial direction and the axial direction of the rotor 1 are received by the air film, so that the rotation loss can be reduced. In addition, as a secondary effect, since the rotating shaft 2 and the rotor 1 are in contact with each other only at the inclined portion 2a when stationary, since the contact area is considerably smaller than that of the conventional one, the stiction is obtained. Can be prevented. Furthermore, in carrying out this example,
Since it can be manufactured by applying the conventional semiconductor manufacturing process, mass production is possible.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of a minute rotation mechanism of the present invention.

FIG. 2 is a manufacturing process diagram of an embodiment of the minute rotation mechanism of the present invention.

FIG. 3 is a manufacturing process diagram of an embodiment of the minute rotation mechanism of the present invention.

FIG. 4 is an explanatory diagram showing an example of a groove pattern of a dynamic pressure bearing portion.

FIG. 5 is a configuration diagram showing an example of a conventional minute rotation mechanism.

FIG. 6 is a configuration diagram showing an example of a conventional minute rotation mechanism.

FIG. 7 is a manufacturing process diagram of a minute rotation mechanism of a conventional example.

FIG. 8 is a manufacturing process diagram of a minute rotation mechanism of a conventional example.

FIG. 9 is a manufacturing process diagram of a minute rotation mechanism of a conventional example.

[Explanation of symbols]

 1 Rotor 1a Dynamic pressure bearing part 2 Rotating shaft 2a Inclined part 4 Substrate

Claims (3)

[Claims] 1. In a micro-rotation mechanism having a rotating shaft on a substrate and rotated by a rotor, a line of intersection between a surface of the rotating shaft facing the rotor and a plane including a central axis of the rotating shaft is: A minute rotation mechanism characterized by being inclined with respect to this central axis. 2. The micro rotating mechanism according to claim 1, wherein a surface of the rotating shaft facing the rotor has a groove. 3. The micro rotation mechanism according to claim 2, wherein the groove has a fishbone shape.