JP2003019700A - Micro structure and method of manufacturing it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a micro structure, wherein manufacturing equipment and cost are inexpensive, and process conditioning is easy, and a desired structure can be formed with a high accuracy and ease, and device design is easy. SOLUTION: In the method of manufacturing the micro structure having a section 3 which is supported on a single crystal silicon substrate 1 having a face orientation 110 as a main face by a beam 2, a plurality of substrates penetrating through parallelogram holes 4 having specified internal angles, which are surrounded by side walls having an equivalent face perpendicular 111 to a substrate face and a silicon film section 6 perpendicular to the substrate face between the substrate penetrating through holes 4 are formed by working the substrate 1 by applying anisotropic etching to the substrate 1. After that, the silicon film section 6 is removed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microstructure formed by processing a silicon substrate, its manufacturing method, and the like.

[0002]

2. Description of the Related Art Conventionally, in the microfabrication of a single crystal silicon substrate, a combination of semiconductor process technology and an anisotropic etching method using an alkaline aqueous solution such as potassium hydroxide has been used to produce various pressure sensors, acceleration sensors and the like. Microstructures have been made. According to this method, a complicated structure can be accurately manufactured even though it is a simple wet etching.

However, the anisotropic etching is (1
11) Since the shape is produced by utilizing the fact that the etching rate of the surface is very slow with respect to other azimuth planes, there are many restrictions on the obtained shape, and it is not possible to design a free structure. A certain degree of control is possible by providing a sacrificial layer or providing a correction pattern on the etching mask, but there is a problem that it is difficult to design the pattern and control the etching time.

On the other hand, in recent years, a dry etching technique has been developed, and TM etching (Time Moderation Etching), in which etching is performed while forming a protective film on the wall surface,
Low temperature etching that suppresses side etching by lowering the temperature of the wafer, and further, an etching method using high density plasma such as inductively coupled plasma and helicon wave plasma has been developed, and the vertical anisotropy is large, and The ability to perform dry etching with a high etching rate has revolutionized the bulk micromachining of silicon (Technical Digest of th
^{e 11 th SensorSymposium, 1992. pp.15~18)} . In these methods, the restrictions on the shape in anisotropic etching are reduced, and it becomes possible to perform an etching process in which an arbitrary mask pattern formed on the substrate surface is directly projected in the vertical direction.

[0005]

However, the processing by dry etching as described above has a problem that the apparatus is expensive. Further, there is a problem that the production cost is high because the amount that can be processed at one time is limited. In addition, there is a problem that the etching rate is smaller than that of wet etching and that it takes time to manufacture. In addition, it is difficult to determine the process conditions. For example, there are cases where the progress of etching is stopped halfway and the through hole is not formed. Further, when forming a through hole having a high aspect ratio, a phenomenon called a microloading effect in which the etching rate changes depending on the opening diameter may be observed. Further, there is another problem that device design for manufacturing a structure is not easy because the device size depends on the process conditions due to the above problem.

The present invention has been made in view of the above-mentioned viewpoints, and its objects are (1) a manufacturing apparatus and a manufacturing cost are low, (2) process conditions are easily determined, and a desired structure is improved. (3) To provide an optical device such as a method for manufacturing a microstructure, a microstructure, a scanner using the microstructure, an image forming apparatus, and the like, which can be easily formed with high accuracy and (3) which facilitates device design. .

[0007]

A method of manufacturing a microstructure according to the present invention that achieves the above object has a portion supported by a beam on a single crystal silicon substrate having a plane orientation (110) as a main surface. A manufacturing method for manufacturing a microstructure, comprising: (1) processing the substrate by anisotropic etching to form a parallelogram having a predetermined inner angle surrounded by side walls of a (111) equivalent plane perpendicular to the substrate surface. Multiple board through holes,
And a step of forming a silicon thin film portion perpendicular to the substrate surface between the through holes of the substrate, and (2) a step of removing the silicon thin film portion.

As described above, according to the present invention, firstly, the plane orientation (1
The present invention relates to a method of manufacturing a microstructure for processing a silicon substrate having 10) as a main surface. In the present specification, a plane equivalent to the (111) plane, for example, (-1-1-
The (1) plane, the (-111) plane, etc. are collectively referred to as the (111) equivalent plane.

In the present invention, the crystal anisotropic etching of silicon utilizes the fact that the etching rate of the (111) equivalent plane is extremely slow. Therefore, all sides are (11
1) Through holes surrounded by equivalent planes can be manufactured with good controllability. Therefore, in the method for manufacturing a microstructure according to the present invention, first, a plurality of through holes surrounded by (111) equivalent planes are formed so that adjacent through holes are partially separated by a silicon thin film portion, and then, By removing the silicon thin film portion, even a microstructure having a complicated shape can be manufactured with good controllability. Therefore, this manufacturing method has features that the manufacturing apparatus and manufacturing cost are low, process conditions are easily set, a desired structure can be easily formed with high precision, and device design is easy.

Further, in the microstructure of the present invention which achieves the above object, a portion supported by a beam on a single crystal silicon substrate having a plane orientation (110) as a main surface (supported on the silicon substrate by a beam which is a torsion bar). Movable structure), the silicon substrate has through holes processed by anisotropic etching around the portion, and the surface of the microstructure is the same as the substrate surface. It is characterized in that it is composed of parallel planes and (111) equivalent planes only.

As described above, the present invention is secondly a microstructure having a through hole formed by etching a silicon substrate and a portion formed in the through hole. The surface relates to a microstructure composed of a plane parallel to the substrate plane and a (111) equivalent plane formed by crystal anisotropic etching.

Since this microstructure is composed of single crystal silicon, it has excellent mechanical properties (that is, it is relatively lightweight, but also has excellent physical strength, durability and life).
Since it is composed of etched crystal planes, it has the advantage of being a structure that is resistant to damage due to stress concentration. In particular,
A movable member having a beam such as a torsion bar or a cantilever has an effect of reducing breakage of the beam.

Further, the micro-scanner of the present invention which achieves the above object, comprises the above-mentioned micro-structure and a driving means for driving the movable part which acts as a deflector by applying an external force to the movable part. Characteristically, an image display device of the present invention that achieves the above object, comprises the above-mentioned microscanner and a light source having a modulation means, irradiates the movable part of the microscanner with a light beam emitted from the light source, It is characterized in that the reflected light from the movable portion is scanned by the driving means. Since these optical devices also use the above-mentioned microstructure, they have the features of the above-mentioned microstructure.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION A more specific embodiment of the present invention will be described below. In the basic method for manufacturing a microstructure, in the step (1), mask layers are formed on both surfaces of the substrate, and the mask layers on both surfaces are patterned to form a plurality of parallelogram-shaped parallelograms each having a predetermined inner angle. The step of forming an opening may be performed and anisotropic etching is performed from both surfaces of the substrate.

As described above, in the method of forming a through hole, typically, mask layers are first formed on both surfaces of a silicon substrate having a plane orientation (110) as a main surface, and the mask layers are formed by photolithography and etching. Patterning is performed to form an etching mask. At this time, each side of the opening of the patterned mask layer has a (111) plane perpendicular to the (110) plane.
It is formed to be a line parallel to the equivalent plane. Therefore,
The opening inevitably becomes a parallelogram opening having a predetermined inner angle, and by extension, the substrate through hole formed by utilizing this is also surrounded by the side wall of the (111) equivalent plane perpendicular to the substrate surface. It becomes a parallelogram through hole having a predetermined interior angle.

After that, a through hole is formed by performing crystal anisotropic etching of the silicon substrate. For anisotropic etching, an aqueous solution of potassium hydroxide, sodium hydroxide, ethylenediamine, tetramethylammonium hydroxide or the like can be used. Anisotropic etching is an excellent method that does not require changing etching conditions depending on the area, thickness, and pattern shape of the substrate. At this time, it is possible to form a through hole having a wall surface perpendicular to the (110) substrate surface by aligning at least a part of the patterns of the mask layers on both surfaces when viewed from the substrate upper surface.

In the step (1), a mask layer is formed on one surface of the substrate, and the mask layer is patterned to form parallelogrammic openings having the predetermined interior angles, and the other side of the substrate is formed. Of the pattern shape complementary to the pattern shape of the mask layer (that is, the opening portion of the mask layer becomes the material portion of the sacrificial layer pattern, and the material portion of the mask layer becomes the opening portion of the sacrificial layer pattern). It is also possible to provide a sacrificial layer of polysilicon, cover the sacrificial layer with a protective layer, and perform anisotropic etching from one surface of the substrate. A pre-patterned polysilicon sacrificial layer is provided on the back surface and the sacrificial layer is
By covering with a protective layer such as N, it is possible to form the substrate through hole by etching from the front side without patterning the mask layer on the back side.

In the step (1), a small through hole may be formed in advance in a portion where the substrate material is likely to remain in the opening of the mask layer, and then anisotropic etching may be performed. When forming a through hole in a narrow region, it may be difficult to form the through hole due to the influence of the (111) equivalent surface that intersects the (110) substrate surface at an angle. In such a case, a smaller through hole may be formed by laser processing or the like in a portion of the mask layer where the material is likely to remain, and then anisotropic etching may be performed to form a through hole having a regular shape. It is possible.

Further, the method may further include the step of separately reducing the thickness of the beam. The beam may be a cantilever beam or a torsion bar.

The through-hole in the step (1) may include a plurality of slit-like through-holes which are continuously arranged with the silicon thin film portion interposed therebetween. In this case, by removing the silicon thin film portion, it is possible to fabricate a microstructure having side surfaces formed by curved surfaces approximated by polygons. This allows
It is also possible to form a through hole in which a relatively free pattern such as a circle is projected. At this time, in order to finish the curved surface smoothly, a process such as etching or polishing may be separately provided. The lengths of the plurality of slit-shaped through holes gradually change substantially continuously.

The step (2) may be a step of anisotropic etching, a step of wet etching, or a step of thermally etching the silicon thin film portion followed by wet etching as in the step (1). It may be a removing step. As described above, the method of removing the silicon thin film portion is wet etching using an alkaline aqueous solution, a mixed aqueous solution of hydrofluoric acid / nitric acid / acetic acid, or a gas such as sulfur fluoride, carbon fluoride, or xenon fluoride. Dry etching, or a method of once oxidizing the silicon thin film portion and selectively etching it.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A more specific embodiment will be described below with reference to the drawings.

<First Embodiment> A first embodiment will be described with reference to FIGS. 1 and 2.
Will be explained. The present example is a movable part 3 supported by a torsion bar 2 which is the first mode of the microstructure according to the present invention, and a method for manufacturing the same. The microstructure according to the present embodiment is a single crystal silicon substrate 1 having a (110) main surface.
A through-hole formed in the above, two torsion bars 2 extending along a straight line, and a movable portion 3 supported by the torsion bar 2 (see FIG. 1A). Each of the torsion bars 2 has a length of 1 mm and a cross-sectional area of 0.015 mm ² . The area of the movable portion 3 is 1 mm ² . All the wall surfaces of the through hole, the torsion bar 2, and the movable portion 3 other than the surface parallel to the surface of the (110) substrate 1 are constituted by the (111) equivalent surface perpendicular to the surface of the substrate 1.

The manufacturing process of the microstructure according to this embodiment will be described with reference to FIG. FIG. 2 shows a cross section taken along the line AA ′ of FIG.

First, a single crystal silicon substrate 1 having a plane orientation (110) as a main surface is prepared, and a mask layer 5 made of silicon nitride is deposited on the front and back surfaces by low pressure chemical vapor deposition using dichlorosilane and ammonia. (Fig. 2 (a)
reference).

Next, the front and back mask layers 5 were patterned by photolithography and a reactive ion etching method using carbon tetrafluoride gas (see FIG. 2B). At this time, the mask layer 5
The patterning was performed so that the side of the opening of the pattern was parallel to the (111) equivalent plane perpendicular to the (110) substrate surface. Further, the patterns of the front and back mask layers 5 were formed so as to match each other when viewed from the upper surface of the substrate 1.

Next, the substrate 1 is subjected to crystal anisotropic etching using a 30% potassium hydroxide aqueous solution heated to 100 ° C. to expose the (111) equivalent plane, thereby forming a sidewall and a vertical plane. The silicon thin film portion 6 was formed (see FIG. 2C).

Further, similar etching was continued to form a through hole 4 (see FIGS. 1 (b) and 2 (d)).
By matching the pattern of the mask layer 5 when viewed from the upper surface of the substrate 1, it is possible to form the through hole 4 having a wall surface perpendicular to the substrate surface.

Further, by continuing the same etching, the side etching of the (111) equivalent plane was advanced to remove the silicon thin film portion 6 (see FIG. 2 (e)).
In this state, the exposed portion of silicon is a (111) equivalent plane with a very low etching rate.
The (111) equivalent surface itself is slightly etched (side etching). As a result, the silicon thin film portion 6 can be removed.

Finally, the mask layers 5 on both sides were removed by a reactive ion etching method using carbon tetrafluoride gas (see FIG. 2 (f)). Through the above steps, a microstructure having the movable portion 3 supported on the substrate 1 by the pair of torsion bars 2 shown in FIG.

In the microstructure according to the present embodiment, the movable portion 3 is rotatable around the major axis of the torsion bar 2, and typically, it can be used as a movable mirror having the surface of the movable portion 3 as a reflecting surface. It is possible.

The manufacturing method of the microstructure of this embodiment is as follows.
The manufacturing apparatus and manufacturing cost are low, process conditions can be easily set, a desired structure can be easily formed with high precision, and device design is easy. Moreover, by performing etching from both sides of the (110) substrate 1, it is possible to perform etching at a high speed. In addition, the microstructure of the present embodiment is excellent in mechanical properties because it is composed of single crystal silicon, and is strong against damage due to stress concentration because it is composed of an etched crystal surface (which is a smooth surface). It has an effect of reducing breakage of the torsion bar 2.

<Second Embodiment> A second embodiment will be described with reference to FIGS. 3, 4, and 5. The present example is a weight portion 12 supported by a cantilever 11 which is a second aspect of the microstructure according to the present invention, and a method for manufacturing the weight portion 12. In the microstructure according to the present embodiment, the through hole 4 and the cantilever 1 formed in the single crystal silicon substrate 1 having (110) as the main surface are formed.
1, and a weight portion 12 supported by the cantilever 11.
(See FIG. 3). The length of the cantilever 11 is 1 m
m, the cross-sectional area is 0.01 mm ² . (110) Substrate 1 of Through Hole 4, Cantilever 11, and Weight 12
All wall surfaces other than the surface parallel to the surface are composed of (111) equivalent surfaces. This (111) equivalent plane is (11
0) A (111) equivalent plane perpendicular to the surface of the substrate 1 and a (111) equivalent plane intersecting obliquely with the surface of the substrate 1 in the dug portion 15 of the cantilever 11 are included.

FIG. 4 shows a manufacturing process diagram of the microstructure according to the present embodiment. Further, FIG. 5 shows a cross-sectional view taken along the line BB ′ in the manufacturing process of FIG.

First, a single crystal silicon substrate 1 having a plane orientation (110) as a main surface is prepared, and a silicon nitride layer 13 is deposited on the front surface and the back surface by a low pressure chemical vapor deposition method using dichlorosilane and ammonia. Patterning was performed by lithography and a reactive ion etching method using carbon tetrafluoride gas. Next, the surface of the substrate 1 is thermally oxidized to form a silicon oxide layer 14 in a portion other than the silicon nitride layer 13, and patterned by photolithography and a wet etching method using a mixed aqueous solution of hydrofluoric acid and ammonium fluoride. (See FIG. 4 (a) and FIG. 5 (a)). Also in this case, the side of the opening of the pattern of the silicon oxide layer 14 is perpendicular to the (110) substrate surface by (1
11) Patterning was performed so as to be parallel to the equivalent plane.

Next, as in the first embodiment, anisotropic etching is performed using an aqueous solution of potassium hydroxide to form the silicon thin film portion 6 and the through hole 4, and the etching is continued to support the cantilever 11. Taori part 12
After forming the microstructure having, the substrate 1 was thermally oxidized to cover the portion other than the silicon nitride layer 13 again with the silicon oxide layer 14 (see FIGS. 4B and 5B).

Next, only the front and back silicon nitride layers 13 were selectively removed by a reactive ion etching method using carbon tetrafluoride gas (FIGS. 4 (c) and 5).
(See (c)).

Next, anisotropic etching is performed using an aqueous solution of TMAH (tetramethylammonium hydroxide) heated to 90 ° C. to form a dug portion 15 at the center of the cantilever 11 and newly form the surface of the substrate 1. A (111) equivalent plane was formed that intersects with each other obliquely (see FIG. 4D and FIG. 5D). A method of oxidizing the side surface of the beam and etching the beam from above and below to reduce the beam thickness is disclosed by etching using xenon fluoride gas (Sensors and Actuators, A6).
6, pp.268-272).

Finally, the silicon oxide layer 14 was removed by a wet etching method using a mixed aqueous solution of hydrofluoric acid and ammonium fluoride, and a microstructure having a weight portion 12 supported by the substrate 1 by the cantilever 11 was manufactured. (See FIG. 4 (e) and FIG. 5 (e)).

The microstructure according to this embodiment has a structure in which the cantilever 11 bends when a force is applied to the weight portion 12. Therefore, for example, by forming a piezoresistive sensor on the cantilever 11, it can be used as an acceleration detection sensor.

The manufacturing method of the microstructure of this embodiment is also as follows.
The manufacturing apparatus and manufacturing cost are low, process conditions can be easily set, a desired structure can be easily formed with high precision, and device design is easy. Further, the microstructure of the present example is also excellent in mechanical properties because it is made of single crystal silicon, and is strong against breakage due to stress concentration because it is made of an etched crystal plane, and has an effect of reducing breakage of the cantilever. Have. Also, the spring constant can be controlled by controlling the thickness of the cantilever 11.

<Third Embodiment> A third embodiment will be described with reference to FIG. In the present embodiment, the circular movable part 2 supported by the torsion bar 2 which is the third aspect of the microstructure according to the present invention.
1 and its manufacturing method. The microstructure according to the present example comprises a through hole formed in a single crystal silicon substrate 1 having (110) as a main surface, a torsion bar 2, and a circular movable portion 21 supported by the torsion bar 2 (FIG. 6). reference). Each pair of torsion bars 2 is 1m long
m, the cross-sectional area is 0.015 mm ² . Circular movable part 21
Has an area of 0.7 mm ² . In the case of this embodiment, the side wall of the circular movable portion 21 is not a (111) equivalent surface but a curved surface.

The manufacturing method is almost the same as the method shown in FIG. 2 of the first embodiment. The points different from Example 1 are shown below.

First, in the step of FIG. 2B, the mask layer 5 is formed.
2 is formed by dividing a part of the opening pattern formed in FIG.
In the step corresponding to (d), the slit-shaped through holes 22 arranged continuously as shown in FIG. 6B were formed.

Secondly, in the step of FIG. 2E of the first embodiment,
Although the silicon thin film portion 6 was removed by continuing the anisotropic etching, in this embodiment, after the surface of the substrate 1 including the silicon thin film portion 6 is thermally oxidized to oxidize the entire silicon thin film portion 6, The oxidized silicon thin film portion 6 was removed by a wet etching method using a mixed aqueous solution of hydrofluoric acid and ammonium fluoride. By this method, FIG.
The side wall of the circular movable portion 21 as shown in (a) could be constructed with a smooth curved surface.

The microstructure according to this embodiment can be used as a movable mirror as in the first embodiment. In the present embodiment, by making the movable portion 21 circular, it is possible to reduce the weight and reduce the air resistance, and it is possible to improve the stability and frequency characteristics in resonance motion.

The manufacturing method of the microstructure of this embodiment is also as follows.
The manufacturing apparatus and manufacturing cost are low, process conditions can be easily set, a desired structure can be easily formed with high precision, and device design is easy. Also, the microstructure of this example is also excellent in mechanical properties because it is made of single crystal silicon, and is strong against damage due to stress concentration because it is composed of etched crystal planes, and reduces breakage of the torsion bar. Have an effect.

<Embodiment 4> This embodiment is a microscanner and an image display device using the microstructure according to Embodiment 1.

The structure of the microscanner of this embodiment will be described with reference to FIG. First, the lower substrate 31 is arranged to face the lower portion of the microstructure according to the first embodiment with a constant gap. At the position of the lower substrate 31 facing the movable portion 3,
Two drive electrodes 32 are provided, and an electrostatic force is generated between the movable portion 3 and the drive electrode 32 by individually applying a voltage to the drive electrodes 32. By irradiating the reflecting surface of this micro-scanner with a light beam, the movable portion 3 is excited by the electrostatic resonance force at the torsional resonance frequency of the torsion bar 2 to continuously rotate and oscillate the reflecting surface. It can be used as a line scanner for original deflection. It is also possible to make a two-dimensional optical scanner by combining with another scanner.

Next, the structure of the image display apparatus of this embodiment will be described with reference to FIG. Reference numeral 41 is an optical deflector group in which two microscanners are arranged so that the deflection directions are orthogonal to each other, and it is possible to raster scan the incident light in the horizontal and vertical directions. The optical deflector group 41 includes the microscanner shown in FIG. 42 is a laser light source having a modulation means. Reference numeral 43 is a correction optical system, and 44 is a screen. The laser light incident from the laser light source 42 is subjected to predetermined intensity modulation related to the timing of optical scanning,
Two-dimensional scanning is performed by the optical deflector group 41. The scanned laser light passes through the correction optical system 43 and forms an image on the screen 44.

In the microscanner according to the present embodiment, by using the microstructure according to the first embodiment, breakage of the beam such as the torsion bar in the movable member can be reduced.

[0052]

As described above, according to the present invention,
Manufacturing equipment and manufacturing cost are low, control of process conditions such as etching conditions is easy, a desired structure can be easily formed with high precision, and a method for manufacturing a microstructure that facilitates device design can be realized. It was Further, when etching is performed from both sides, the through holes could be formed in a short time. Further, in the case of forming slit-shaped through holes that are continuously arranged, a method of manufacturing a microstructure having through holes in which a relatively free two-dimensional pattern is projected can be realized.

Further, according to the present invention, it is possible to realize a microstructure which is excellent in mechanical properties because it is made of single crystal silicon and which is resistant to breakage due to stress concentration because it is made of an etched crystal plane. In particular, a movable member having a beam such as a torsion bar or a cantilever has an effect of reducing breakage of the beam. In addition, by making the movable part supported by the torsion bar circular, it was possible to reduce weight and reduce air resistance, and to improve stability and frequency characteristics in resonance motion.

[Brief description of drawings]

FIG. 1 is a perspective view showing a part of a microstructure and its manufacturing process according to a first embodiment.

2A to 2C are cross-sectional views showing a manufacturing process of a microstructure according to Example 1.

FIG. 3 is a perspective view showing a microstructure according to a second embodiment.

FIG. 4 is a perspective view showing a manufacturing process of a microstructure according to a second embodiment.

5A to 5C are cross-sectional views showing a manufacturing process of a microstructure according to Example 2.

6A and 6B are diagrams showing a microstructure according to Example 3 and a part of a manufacturing process thereof.

FIG. 7 is a perspective view showing a micro scanner according to a fourth embodiment.

FIG. 8 is a schematic diagram showing an image display device according to a fourth embodiment.

[Explanation of symbols]

1 (110) Silicon substrate 2 torsion bar 3 moving parts 4 through holes 5 Mask layer 6 Silicon thin film part 11 cantilevers 12 Weight section 13 Silicon nitride layer 14 Silicon oxide layer 15 Digging section 21 circular movable part 22 Slit-shaped through hole 31 Lower substrate 32 drive electrode 41 Optical deflector group 42 Laser light source 43 Correction optical system 44 screen

Claims (21)

[Claims] 1. A manufacturing method for manufacturing a microstructure having a portion supported by a beam on a single crystal silicon substrate having a plane orientation (110) as a main surface, comprising: (1) anisotropic etching of the substrate. And a plurality of parallelepiped substrate through holes each having a predetermined inner angle and surrounded by side walls of a (111) equivalent plane perpendicular to the substrate surface, and perpendicular to the substrate surface between the substrate through holes. A method of manufacturing a microstructure, comprising: a step of forming a silicon thin film portion; and (2) a step of removing the silicon thin film portion. 2. The step (1) comprises forming mask layers on both surfaces of the substrate, and patterning the mask layers on both surfaces to form parallelogrammic openings of the predetermined interior angle. The method for producing a microstructure according to claim 1, which is a step of performing anisotropic etching from both sides of. 3. The method for producing a microstructure according to claim 2, wherein at least a part of the pattern shapes of the mask layers formed on the both surfaces are the same when viewed from the upper surface of the substrate. 4. In the step (1), a small through hole is previously formed in a portion of the opening of the mask layer where the substrate material is likely to remain, and then anisotropic etching is performed. Alternatively, the method for producing a microstructure according to the item 3. 5. In the step (1), a mask layer is formed on one surface of the substrate, and the mask layer is patterned to form a parallelogrammic opening having the predetermined interior angle. A polysilicon sacrificial layer having a pattern complementary to the pattern of the mask layer is provided on the other surface of the substrate to cover the sacrificial layer with a protective layer, and anisotropic etching is performed from one surface of the substrate. The method for producing a microstructure according to claim 1, wherein 6. The method for manufacturing a microstructure according to claim 1, wherein the beam is a cantilever beam. 7. The method of manufacturing a microstructure according to claim 1, wherein the beam is a torsion bar. 8. The method according to claim 1, wherein the through hole in the step (1) includes a plurality of slit-shaped through holes that are continuously arranged with the silicon thin film portion sandwiched therebetween. The method for producing a microstructure according to item 1. 9. The method for producing a microstructure according to claim 8, wherein the lengths of the plurality of slit-shaped through holes gradually and substantially continuously change. 10. The method for producing a microstructure according to claim 8, further comprising a separate etching, polishing, or other step for finishing the curved surface of the portion smoothly. 11. The method for producing a microstructure according to claim 1, wherein the step (2) is performed by anisotropic etching similarly to the step (1). 12. The method for producing a microstructure according to claim 1, wherein the step (2) is wet etching. 13. The method for producing a microstructure according to claim 1, wherein in the step (2), the silicon thin film portion is thermally oxidized and then removed by wet etching. 14. The method of manufacturing a microstructure according to claim 1, further comprising the step of separately reducing the thickness of the beam. 15. A microstructure having a portion supported by a beam on a single crystal silicon substrate having a plane orientation (110) as a main surface, wherein the silicon substrate is processed by anisotropic etching around the portion. The microstructure having a through hole formed therein, the surface of the microstructure being constituted only by a plane parallel to the substrate surface and a (111) equivalent plane. 16. The microstructure according to claim 15, having a plurality of continuous slit-shaped through holes. 17. The microstructure according to claim 15, wherein the beam is a cantilever. 18. The microstructure according to claim 15, wherein the beam is a torsion bar. 19. The microstructure according to claim 18, further comprising a movable portion supported by the silicon substrate by the torsion bar. 20. A micro-scanner comprising: the microstructure according to claim 19; and a driving unit that drives the movable unit that acts as a deflector by applying an external force to the movable unit. 21. A microscanner according to claim 20 and a light source having a modulation means, wherein the movable part of the microscanner is irradiated with a light beam emitted from the light source, and reflected light from the movable part. An image display device, characterized in that the image is scanned by the driving means.