JP2003270559A - Microdevice and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize high reliability and driving characteristics as to a device which is suitably used for an optical switch and its manufacturing method. <P>SOLUTION: The microdevice has a displacement part 11 which is provided with a mirror 21 as a function element and moves the mirror 21 by a driving electrode 20 disposed at a base part 12 and a support frame 14 which supports the displacement part 11; and the displacement part 11 is formed by using an SOI substrate 30 constituted by joining 1st and 2nd bulk layers 31 and 32 as bulks of single-crystal silicon together across an intermediate layer 33 and processing the SOI substrate 30 by reactive ion etching as a bulk micromachining technique. At this time, the intermediate layer 33 is used as an etching stop material for the reactive ion etching. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a micro device and a manufacturing method thereof, and more particularly to a micro device suitable for use in an optical switch and a manufacturing method thereof.

[0002]

2. Description of the Related Art Microdevices formed by integrating fine-structured parts are applicable in various fields such as optical switches, lab-on-chips, microchromatography devices, micropumps, power MEMS parts, etc. Is expected. Among these micro devices, for example, an optical switch is a device related to optical communication, or Dense Wavelength Division Multiplexing.
g: DWDM) Demand for related equipment is increasing.

The structure of the optical switch can be roughly classified into two types, mechanical type and non-movable type. A non-movable optical switch generally uses a waveguide, which brings the characteristics of a coupler in which adjacent fibers are brought close to each other up to the transmission wavelength, and electromagnetic energy is transferred from one fiber to the other due to the leakage of light between them. We are using. The non-movable optical switch as described above can suppress the switch loss and the like to a low level. However, there is a problem that crosstalk between adjacent fibers becomes large.
The need for an n-blocking configuration necessitates the arranging of a large number of switch elements, which inevitably increases the size.

On the other hand, the mechanical type optical switch is more advantageous than the above-mentioned non-movable type optical switch from the viewpoints of crosstalk reduction, large scale, and the like. As the mechanical optical switch, there is a movable mirror switching type optical switch that switches the optical path by fixing the position of the optical fiber and moving the mirror with respect to the optical path.

Since the movable mirror switching type optical switch has a structure in which the optical path is switched by moving the mirror in and out as described above, it is necessary to move the mirror with respect to the optical path. For this reason, the optical switch is provided with a drive mechanism for moving the mirror. This drive mechanism has a movable arm to which the mirror is attached, and a drive means for moving and urging the movable arm.

In order to realize a highly reliable optical switch, the movable arm for driving the mirror is configured to move flexibly in the moving direction of the mirror and not move in a direction other than the moving direction of the mirror. Is important. The movable arm has been formed from a laminated substrate in which a polysilicon (polycrystalline silicon) film and a silicon dioxide (SiO ₂ ) film are laminated.

Specifically, a substrate in which a polysilicon film and a silicon dioxide film are laminated is prepared, and a silicon dioxide (SiO ₂ ) film on this substrate is etched and removed in a predetermined pattern to form a movable arm. . Therefore, in the conventional optical switch, the movable arm is formed of polylithicon. The technique for finely processing a plurality of laminated films in this way is called "surface micromachining".

An optical switch realized by using this surface micromachining technique is disclosed in, for example, Japanese Patent Application Laid-Open No. 2000-258702. The optical switch disclosed in this publication has a structure in which a support (movable arm) for driving a mirror for switching an optical path is formed of polysilicon.

[0009]

As disclosed in the above publication, the conventional optical switch has a structure in which the movable arm (support) for driving the mirror is made of polysilicon. This polysilicon film is a deposited film usually formed by the CVD (vapor phase growth) method.

As described above, the movable arm (support) formed as a deposited film of polysilicon has (1) a lower Young's modulus and is prone to plastic deformation than the bulk of single crystal silicon. (2) Crystal grains (3) There is a problem that residual stress at the time of CVD has a bad influence on the formation of the movable arm etc.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a microdevice capable of realizing high reliability and driving characteristics, and a manufacturing method thereof.

[0012]

In order to solve the above problems, the present invention is characterized by taking the following means.

According to a first aspect of the present invention, a microdevice is provided which is provided with a functional element and which has a displacement portion which is displaced by a driving means to move the functional element, and a support portion which supports the displacement portion. In the above, the displacement portion is formed by using a bulk micromachining technique.

According to the above invention, since the displacement portion is formed by using the bulk micromachining technique, the strength of the displacement portion is improved as compared with the structure in which the displacement portion is formed by laminating thin films by using the thin film technique. be able to. Therefore,
It is possible to prevent plastic deformation and strain from occurring in the displacement portion due to the displacement operation, and improve the reliability of the microdevice.

The invention according to claim 2 is the microdevice according to claim 1, characterized in that the displacement portion is a bulk of single crystal silicon.

According to the above invention, since the displacement portion is made of a bulk of single crystal silicon, the reliability of the microdevice can be improved. That is, the bulk of single crystal silicon has higher mechanical strength than polysilicon in which silicon thin films are stacked by using thin film technology. Therefore, by using a bulk of single-crystal silicon for the displacement portion, it is possible to prevent plastic deformation and strain from occurring due to the displacement operation of the displacement portion, and thus improve the reliability of the microdevice.

According to a third aspect of the present invention, in the microdevice according to the first or second aspect, the supporting part is formed of a bulk of single crystal silicon, and the displacement part and the supporting part are made of an insulating material. It is characterized by being joined through an intermediate layer having.

According to the above invention, the insulating intermediate layer is interposed between the displacement portion made of the bulk of single crystal silicon and the support portion also made of the bulk of single crystal silicon. An SOI substrate can be used as a base material for forming the.

According to a fourth aspect of the present invention, in the microdevice according to any one of the first to third aspects, the functional element is a mirror that switches an optical path of light by the displacement. To do.

According to the above invention, the microdevice can be used as an optical switch.

According to a fifth aspect of the present invention, in the microdevice according to the fourth aspect, the mirror is configured to stand upright on the displacement portion.

According to the above invention, it is possible to make the light switching to the optical switch enter from the direction orthogonal to the displacement direction of the mirror. Therefore, the structure of the microdevice (optical switch) can be simplified as compared with the structure in which the light to be switched to the optical switch is incident in parallel with the displacement direction of the mirror.

According to a sixth aspect of the present invention, in the microdevice according to any one of the first to fifth aspects, the driving means includes the displacement portion of the base on which the support portion is arranged. It is characterized in that it has electrodes arranged at opposing positions to electrostatically attract the displacement portion by applying a drive voltage.

According to the above invention, the driving means can be made compact by disposing the electrode for driving the displacement portion on the base on which the supporting portion is disposed, and therefore the microdevice can be made compact. Can be realized.

According to a seventh aspect of the present invention, there is provided a microdevice including a functional element, a displacement section for displacing the functional element and moving the functional element, and a supporting section for supporting the displacement section. In the method, the first displacement part
A bulk layer, a second bulk layer serving as the supporting portion, and an intermediate layer provided between the first bulk layer and the second bulk layer, and And a step of processing the second bulk layer by bulk micromachining using the intermediate layer as an etch stop material.

According to the above invention, since the second bulk layer is subjected to bulk micromachining using the intermediate layer as an etch stop material, it is possible to prevent the second bulk layer from being processed beyond the intermediate layer. . This makes it possible to accurately form the displacement portion and prevent the bulk micromachining process from reaching the first bulk layer. Therefore, the displacement portion and the support portion can be formed with high accuracy.

The invention described in claim 8 is characterized in that, in the method for manufacturing a microdevice according to claim 7, reactive ion etching is used as the bulk micromachining.

According to the above invention, since the reactive ion etching is used as the bulk micromachining, it is possible to form the groove having the side wall substantially perpendicular to the processed surface of the second bulk layer, and thus the displacement portion is formed. It can be formed with high precision, and thus the functional element can be moved with high precision.

The invention according to claim 9 is the method for manufacturing a microdevice according to claim 7 or 8, wherein the first bulk layer and the second bulk layer are single crystal silicon, and the intermediate layer is It is characterized by using silicon oxide.

Further, the invention according to claim 10 is the invention according to claim 9.
In the method for manufacturing a micro device described above, the substrate is an SOI (Silicon On Insulator) substrate.

According to the invention described in claims 9 and 10, the substrate can be formed by utilizing the SOI technique.

The invention described in claim 11 is the same as claim 7.
11. The method of manufacturing a microdevice according to any one of items 1 to 10, wherein the functional element is simultaneously formed from the second bulk layer when the second bulk layer is processed to form the support portion. It is characterized by.

According to the above-mentioned invention, since the formation of the support portion and the formation of the functional element can be performed at the same time, the processing time can be shortened.

[0034]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described with reference to the drawings.

1 to 3 show a microdevice which is an embodiment of the present invention. In this embodiment, an example in which the optical switch 10 is used as a micro device will be described, but the application of the present invention is not limited to this, and a micro pump, a scanner, a digital mirror device, a pressure sensor, an acceleration sensor, a gyro, etc. It can be applied to various microdevices.

The optical switch 10 is a movable mirror switching type optical switch, and is provided in, for example, a DWDM-related device to switch the optical path of signal light. The optical switch 10 is roughly composed of a displacement section 11 and a base section 1.
2, the support frame 14, and the like.

The displacement portion 11 is made of a bulk of single crystal silicon and is composed of a stage 13, an arm portion 15, a frame portion 16, a mirror 21 and the like. The stage 13, the arm portion 15, the frame portion 16, and the mirror 21 which constitute the displacement portion 11 are integrally formed by using a bulk micromachining technique. Here, the bulk micromachining technology refers to a processing technology for forming a fine structure on the single crystal substrate itself, which is a processing technology that conflicts with the above-mentioned surface micromachining ("Semiconductor Term Dictionary": Nikkan Kogyo Co., Ltd.). Newspaper, March 1999
Issued on the 20th of the month, see page 871, right column).

The stage 13 is a rectangular plate-shaped portion as shown in FIG. 3, and has a mirror 21 (corresponding to a functional element described in the claims) standing upright in the center thereof. The surface of the mirror 21 is mirror-finished. In addition, the mirror 21 is arranged with respect to the line connecting the fiber mounting grooves 18A and 18B formed in the support frame 14 described later.
The structure is inclined by 5 °.

As described above, in this embodiment, the mirror 2
Although 1 is configured integrally with the stage 13, the mirror 21 may be configured separately from the stage 13. In this case, it is conceivable to fix the mirror also to the stage by, for example, bonding.

The arm portion 15 is formed so as to extend from the outer circumference of the stage 13 by four pieces (one or a plurality of pieces may be provided). The arm portion 15 is connected at its stage 13 side and half body side end portions to the frame portion 16. Therefore, the stage 13 is configured to be supported by the frame portion 16 via the arm portion 15.

Further, since each arm portion 15 has a leaf spring shape, it is in the vertical direction in the drawing (direction of arrows Z1 and Z2 in the drawing).
Easily deforms. However, the arm part 1
5 has strong rigidity in the rotation direction indicated by arrow A in FIG. 3 (direction in which the stage 13 rotates in the surface direction) and in the rotation direction indicated by arrow B in FIG. 3 (direction in which each arm portion 15 is twisted). Show. Therefore, the stage 13 supported by the arm portion 15
Has a configuration in which it easily moves in the vertical direction indicated by arrows Z1 and Z2 in the figure, but does not easily move in other directions.

The frame portion 16 has a frame-like shape. The shape of the frame portion 16 in a plan view is configured to be the same as that of the support frame 14 having the same frame shape. That is, the frame portion 16 and the support frame 14 are configured to overlap each other. Further, the frame portion 16 is joined to the support frame 14 via the intermediate layer 33 (made of silicon dioxide) as described later in detail. As a result, the displacement part 1
1 is configured to be supported by the support frame 14.

The support frame 14 (corresponding to the support portion described in the claims) is made of a bulk of single crystal silicon. The support frame 14 has a function of supporting the displacement portion 11 as described above, and at the same time, the optical fiber 1
It has a function of fixing 7A to 17C at predetermined positions. For this reason, the support frame 14 has the optical fiber 1
Fiber mounting groove 18A for fixing 7A to 17C
18C are formed.

The fiber mounting groove 18A and the fiber mounting groove 18B are arranged at positions facing each other linearly.
The fiber mounting groove 18C is the fiber mounting groove 1
8A and the fiber mounting groove 18B are orthogonal to a straight line (indicated by an alternate long and short dash line indicated by arrow C in the figure) connecting the mirror 21
Is formed along a straight line (dotted line indicated by arrow D in the figure) passing through the center point of the arrow (indicated by arrow O in the figure).

Next, the base 12 will be described. The base portion 12 has a structure in which a cavity portion 19 is formed on a glass substrate. The cavity portion 19 can be easily formed by etching the glass substrate with an etching solution in which hydrofluoric acid (HF) and ammonium fluoride (NH ₄ F) are mixed.

In the cavity portion 19,
A drive electrode 20 is formed at a position facing the stage 13. Between the drive electrode 20 and the displacement portion 11,
A voltage applying device (not shown) is connected. Then, by applying a predetermined drive voltage between the drive electrode 20 and the displacement portion 11 by this voltage applying device, the stage 13
Are electrostatically attracted to the drive electrode 20.

As a result, as shown in FIG.
3 is displaced in the direction of the arrow Z1 in the figure, and accordingly the mirror 21
Also moves in the direction of arrow Z1. At this time, in this embodiment, since the drive electrode 20 for driving the displacement portion 11 is provided at a position facing the stage 13 of the base portion 12, the drive electrode 20 can be made compact and compact. You can

In the state where the displacement portion 11 shown in FIG. 1 is not displaced, the mirror 21 is in the raised position. In this state, the light emitted from the optical fiber 17A (indicated by the arrow A in FIGS. 1 and 2) is incident on the mirror 21, whose optical path is changed by 90 ° and is incident on the optical fiber 17C.

On the other hand, when the stage 13 of the displacement portion 11 is displaced in the direction of the arrow Z1 by applying the drive voltage as described above, the light A emitted from the optical fiber 17A does not enter the mirror 21, and the optical fiber 17
It is incident on B. The deformable amount of the arm portion 15, the depth of the cavity portion 19, and the magnitude of the driving voltage are determined by the stage 13
Is displaced in the direction of the arrow Z1 so that the mirror 21 is located below the optical path of the light A from the optical fiber 17A to the optical fiber 17B.

Therefore, the optical switch 10 sets the drive voltage to O
By turning N / OFF, the optical path of the light A emitted from the optical fiber 17A can be selectively switched between the optical path entering the optical fiber 17B and the optical path entering the optical fiber 17C. At this time, in this embodiment, the mirror 21 is set upright with respect to the stage 13.

As described above, by vertically raising the mirror 21 with respect to the stage 13, the light A is moved from the direction orthogonal to the displacement direction of the mirror 21 (Z1 and Z2 directions) (ie, the direction parallel to the stage 13). It becomes possible to enter.
Therefore, the structure of the optical switch 10 can be simplified as compared with the structure in which the light A to be switched is incident from the direction parallel to the displacement direction of the mirror (Z1 and Z2 directions).

That is, the configuration in which the switching light A is incident from the direction parallel to the displacement direction of the mirror (Z1 and Z2 directions) is a configuration in which the stage 13 itself in this embodiment is a mirror. In this configuration, it is necessary to mount the optical fiber so as to face the stage, and the mounting structure is troublesome. Further, it is difficult to move the mirror as compared with the present embodiment.

As described above, when the optical path of the light A is switched, the stage 13 and the arm portion 15 of the displacement portion 11 are displaced in the directions of arrows Z1 and Z2 in the figure. This stage 1
The more frequently the optical path switching process (switching process) is performed, the more the displacement of 3 and the arm portion 15 is performed.

Here, attention is paid to the material of the displacement portion 11 in this embodiment. In the present embodiment, the bulk micromachining technique is used to process the bulk of single crystal silicon to form the displacement portion 11. That is,
The displacement portion 11 is formed of a bulk of single crystal silicon.

As described above, since the displacement portion 11 is formed of the bulk of single crystal silicon, the reliability of the optical switch 10 can be improved. That is, the bulk of single crystal silicon has a higher mechanical strength than polysilicon (conventional structure) in which silicon thin films are stacked by using the surface micromachining technique.

Specifically, the bulk of single crystal silicon is
Compared with polysilicon, Young's modulus is higher and plastic deformation is less likely to occur, and cracks and strains are not caused by stress due to the influence of crystal grain boundaries. Furthermore, unlike polysilicon, CV
Since surface micromachining processing (such as film forming processing) such as D is not performed, residual stress does not adversely affect the displacement portion 11.

Therefore, by making the displacement portion 11 a bulk of single crystal silicon, it is possible to prevent the displacement portion 11 (in particular, the stage 13 and the arm portion 15) from being plastically deformed or strained by the switching process of the light A. Therefore, the reliability of the optical switch 10 can be improved.

Further, the bulk micromachining technology is
Generally, equipment and processing are simpler and processing cost is lower than that of surface micromachining technology. Therefore, the optical switch 10 can be easily and inexpensively manufactured by using the bulk of the single crystal silicon as the displacement portion 11 and processing it by the bulk micromachining technique.

Next, with reference to FIG. 4, a method of manufacturing the optical switch 10 having the above structure will be described. Note that, in FIG. 4, configurations that face the configurations shown in FIGS. 1 to 3 are denoted by the same reference numerals, and description thereof will be omitted.

FIG. 4A shows an SOI (Silicon On Insulator) substrate 30 which is a material for manufacturing the optical switch 10. The SOI substrate 30 includes the first bulk layer 3
1, the intermediate layer 33, and the second bulk layer 32 are laminated. The first bulk layer 31 and the second bulk layer 32 are bulk of single crystal silicon (Si), and the intermediate layer 33 is silicon dioxide (SiO ₂ ).

The SOI substrate 30 is formed by using the well-known SOI technique. Specifically, the SOI substrate 30 is S
It can be formed by using an IMOX (Silicon IMplanted OXide) method or a bonding method. In the SIMOX method, oxygen (O 2) is ion-implanted into a silicon substrate (Si), and then heat treatment is performed to combine with silicon, and a silicon oxide film (Si
This is a method of manufacturing the SOI substrate 30 by forming O ₂ ). In the bonding method, a first silicon substrate having an oxide film formed on its surface and a second silicon substrate separate from the first silicon substrate are adhered to each other under high heat and high pressure, and then the second silicon substrate is subjected to a predetermined process. By grinding to the thickness, SO
This is a method of manufacturing the I substrate 30. The SOI substrate 30
A surface protective layer 34 made of silicon dioxide (SiO ₂ ) is formed on the upper surface (the upper surface of the second bulk layer 32).

On the SOI substrate 30 having the above structure, as shown in FIG. 4B, first, the first photoresist 35 is formed.
Is applied. This first photoresist 35 is
Is applied to the surface protection layer 34 formed on the bulk layer 32 of, for example, using a spinner. The first photoresist 35 may be either a positive type or a negative type.

Then, the first photoresist 35 is exposed and developed to remove the first photoresist 35 in other portions, leaving the upper portions of the portions serving as the support frame 14 and the mirror 21. It FIG. 4C shows a state in which an unnecessary portion of the first photoresist 35 has been removed. As shown in the figure, the first photoresist 35
The second bulk layer 32 is exposed in a portion where the is removed.

When the patterning of the first photoresist 35 is completed as described above, bulk micromachining is subsequently performed on the SOI substrate 30. In this embodiment, reactive ion etching (RIE) is used as bulk micromachining. The SOI substrate 30 is mounted on an etching device that performs reactive ion etching, and the first photoresist 3
Reactive ion etching is performed on the second bulk layer 32 using 5 as a mask.

In this embodiment, reactive ion etching using SF ₆ gas is used. This reactive ion etching is performed with silicon (Si) and silicon dioxide (SiO 2).
One of the major characteristics is that it has a high etch rate selectivity with respect to ₂ ).

The selectivity of this etching rate is Si: SiO2 = (100 to 300): 1, although it depends on the conditions. In the reactive ion etching for gas exchange, the sidewall protection and etching processes are alternately repeated to deeply dig a hole having a sidewall substantially perpendicular to the surface to be machined (deeply machined portion 37 in this embodiment). It can be processed.

FIG. 4D shows a process of forming the deep trench processing portion 37 in the second bulk layer 32 by reactive ion etching. As described above, the reactive ion etching can form a hole having a side wall substantially vertical to the processed surface, but when digging a certain area to a certain depth or more, the flatness of the bottom surface is within several μm. Hard to keep in. For this reason, as shown in FIG. 4D, thickness unevenness 36 is formed on the bottom surface of the deep trench processing portion 37 during processing. The thickness of the thickness unevenness 36 varies depending on the thickness of the second bulk layer 32, the size of the deep trench processing portion 37, and the like, but one side length of the rectangular deep trench processing portion 37 is 500 μm.
If the thickness is about m, the thickness of the thickness unevenness 36 is about 20 to 30 μm.
Becomes

Now, assuming a structure in which the intermediate layer 33 does not exist (a structure in which the first bulk layer 31 and the second bulk layer 32 are integrated), it is possible to control the depth of the deep working portion 37. There is no choice but to control the time, and the accuracy is reduced. Further, the thickness unevenness 36 described above is still generated at the bottom of the deep-drilling processing portion 37.

The control of the depth of the deep trench processing portion 37 is equivalent to the control of the thickness of the displacement portion 11. Therefore, in the configuration in which the intermediate layer 33 does not exist, the displacement portion 11 varies in thickness, the operation of the displacement portion 11 becomes unstable, and the mirror 21 cannot be moved with good responsiveness.

On the other hand, in this embodiment, the intermediate layer 33 made of silicon dioxide (SiO ₂ ) whose reactive ion etching rate is extremely slower than that of silicon (Si) is used as the first bulk layer 31 and the first bulk layer 31. It is provided between the two bulk layers 32. Therefore, the reactive ion etching on the second bulk layer 32 is performed until the intermediate layer 33 is exposed, and after the intermediate layer 33 is exposed, the first reactive ion etching is performed on the first bulk layer 32.
Of the bulk layer 31 is prevented from being etched.

That is, when the etching process is performed on the second bulk layer 32, the intermediate layer 33 becomes the second bulk layer 32.
It functions as an etch stop material that regulates the amount of etching. Therefore, by providing the intermediate layer 33,
As shown in FIG. 4 (E), it is possible to completely remove the thickness unevenness 36 generated at the bottom of the deeply processed portion 37 by the reactive ion etching.

Moreover, since the reactive ion etching does not proceed beyond the intermediate layer 33 functioning as an etch stop material, the first bulk layer 31 is not etched. Therefore, as shown in FIG. 4E, the support frame 14 and the mirror 21 can be formed with high accuracy by performing reactive ion etching using the intermediate layer 33 as an etch stop material. Further, in this embodiment, since the supporting frame 14 and the mirror 21 are simultaneously formed by using reactive ion etching, the processing time can be shortened as compared with the method of separately forming the supporting frame 14 and the mirror 21. ing.

When the support frame 14 and the mirror 21 are formed as described above, the intermediate layer 33 is removed. As a result, as shown in FIG.
The bottom part of 7 is in a state where the first bulk layer 31 is exposed. When the removal of the intermediate layer 33 is completed, the first photoresist 35 is removed.

When the first photoresist 35 is removed, a second photoresist 38 is subsequently applied to the surface of the first bulk layer 31 opposite to the side where the support frame 14 and the mirror 21 are provided. . This second photoresist 38
Is applied using, for example, a spinner. Figure 4 (G)
Shows the state in which the second photoresist 38 is applied. The second photoresist 38 is also of positive type,
Any of the negative type may be used.

Subsequently, the second photoresist 38 is subjected to exposure and development processing, leaving a portion to be the arm portion 15 and a portion to be the stage 13 and removing the second photoresist 38 in other portions. To be done. Figure 4 (H)
Shows a state in which an unnecessary portion of the second photoresist 38 is removed. As shown in the figure, the first bulk layer 31 is exposed in the portion where the second photoresist 38 is removed.

When the patterning of the second photoresist 38 is completed as described above, the first bulk layer 31 is subsequently formed.
Bulk micromachining is performed on. In the present embodiment, reactive ion etching (RI) is also used as bulk micromachining for the first bulk layer 31.
E) is used. Thereby, as shown in FIG. 4I, the first bulk layer 31 is removed by etching except the stage 13 and the arm portion 15.

At this time, by using reactive ion etching, for the same reason as described above, the arm 1
The side surface of 5 is a substantially vertical surface. Therefore, the arm portion 15 can be formed with high dimensional accuracy, and the mirror 21 can be moved with high accuracy and stability.

Subsequently, the second photoresist 38 and the surface protection layer 34 are removed, and the displacement portion 11 is manufactured by the above steps. FIG. 4 (J) shows the displacement portion 11 manufactured through the above manufacturing process. The displacement portion 11 manufactured in this manner is bonded to the base portion 12 on which the cavity portion 19 and the drive electrode 20 are formed in advance, whereby the optical switch 10 shown in FIGS. 1 to 3 is completed. Since the manufacturing method of the base portion 12 is well known, its description is omitted.

As described above, in the method of manufacturing the optical switch 10 (displacement portion 11) according to the present embodiment, the first bulk layer 31 serving as the displacement portion 11 is formed of a bulk of single crystal silicon, and thus the displacement portion is formed. 11 is configured to improve the mechanical strength. When performing bulk micromachining (reactive ion etching) on the second bulk layer 32 made of a bulk of single crystal silicon, the first bulk layer 31 is processed (etched) together with the second bulk layer 32. In order to prevent this, an intermediate layer 33 that functions as an etch stop material is interposed between the bulk layers 31 and 32.

However, the first bulk layer 31 and the second bulk layer 31
The bulk layer 32 does not necessarily have to be a bulk of single crystal silicon. As long as the mechanical strength sufficient to drive the mirror 21 can be realized and the structure can be driven by a driving unit (for example, an electrode that electrostatically attracts the stage 13), resin, metal, or other material can be used. It is also possible to use.

The first bulk layer 31 and the second bulk layer 32 are not necessarily made of the same material, but may be made of different materials. In this case, by making the material of the first bulk layer 31 a material that functions as an etch stop material when the second bulk layer 32 is etched, the intermediate layer 33 can be removed.

[0082]

As described above, according to the present invention, various effects described below can be realized.

According to the invention described in claim 1, since the strength of the displacement portion can be improved as compared with the structure in which the displacement portion is formed by laminating the thin films by using the thin film technique, the displacement portion is not subject to plastic deformation or deformation. Distortion can be prevented and the reliability of the microdevice can be improved.

According to the second aspect of the invention, the bulk of single crystal silicon has a higher mechanical strength than the polysilicon in which the silicon thin films are laminated by using the thin film technique.
It is possible to prevent plastic deformation and strain from occurring in the displaced portion, and thus improve the reliability of the microdevice.
Further, since the displacement portion can be formed by utilizing the semiconductor manufacturing technology, the displacement portion can be easily and inexpensively formed.

According to the third aspect of the invention, since the intermediate layer having an insulating property is interposed between the displacement portion made of the bulk of single crystal silicon and the support portion, a microdevice is formed. An SOI substrate can be used as a base material.

According to the invention described in claim 4, the microdevice can be used as an optical switch.

According to the fifth aspect of the present invention, the structure of the microdevice (optical switch) is simplified as compared with the structure in which the light switched to the optical switch is incident in parallel with the displacement direction of the mirror. be able to.

According to the invention described in claim 6, the driving means can be made compact, and hence the microdevice can be made compact.

Further, according to the invention of claim 7, the second bulk layer is not processed more than the intermediate layer functioning as the etch stop material, so that the accuracy of forming the displacement portion and the support portion is improved. be able to.

Further, according to the invention described in claim 8, since the groove having the side wall substantially vertical to the second bulk layer can be formed by using the reactive ion etching, the displacement portion can be accurately formed. Therefore, the functional element can be moved with high accuracy.

According to the ninth and tenth aspects of the invention, the substrate can be formed by utilizing the SOI technique.

According to the invention described in claim 11, the formation of the support portion and the formation of the functional element can be performed at the same time, so that the processing time can be shortened.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an optical switch according to an embodiment of the present invention, showing a state in which a mirror is raised.

FIG. 2 is a cross-sectional view showing an optical switch according to an embodiment of the present invention, showing a state in which a mirror is lowered.

FIG. 3 is a perspective view showing an optical switch according to an embodiment of the present invention.

FIG. 4 is a diagram showing the method of manufacturing the optical switch according to the embodiment of the present invention along the manufacturing procedure.

[Explanation of symbols]

10 Optical switch 11 Drive 12 base 13 stages 14 Support frame 15 Arm 16 frame 17 optical fiber 18A-18C Fiber mounting groove 19 cavity 20 Drive electrode 21 mirror 30 SOI substrate 31 First bulk layer 32 Second bulk layer 33 Middle class 34 Surface protection layer 35 First Photoresist 36 Thickness unevenness 37 Deep trench processing department 38 Second photoresist

Claims (11)

[Claims] 1. A microdevice provided with a functional element, having a displacement portion that is displaced by a driving means to move the functional element, and a support portion that supports the displacement portion. , A microdevice formed by using a bulk micromachining technique. 2. The microdevice according to claim 1, wherein the displacement portion is a bulk of single crystal silicon. 3. The microdevice according to claim 1, wherein the supporting portion is formed of a bulk of single crystal silicon, and the displacement portion and the supporting portion are joined via an intermediate layer having an insulating property. A microdevice characterized by being formed. 4. The microdevice according to claim 1, wherein the functional element is a mirror that switches an optical path of light by the displacement. 5. The microdevice according to claim 4, wherein the mirror has a structure in which the mirror is erected on the displacement portion. 6. The microdevice according to claim 1, wherein the driving unit is arranged at a position facing the displacement section of a base on which the support section is arranged, A microdevice having an electrode that electrostatically attracts the displacement portion when a drive voltage is applied. 7. A method for manufacturing a microdevice, comprising: a displacement portion provided with a functional element and displaced to move the functional element; and a method of manufacturing a microdevice, comprising: the displacement portion. Forming a substrate comprising a first bulk layer, a second bulk layer serving as the supporting portion, and an intermediate layer provided between the first bulk layer and the second bulk layer; And a step of processing the second bulk layer by bulk micromachining using the intermediate layer as an etch stop material. 8. The method of manufacturing a microdevice according to claim 7, wherein reactive ion etching is used as the bulk micromachining. 9. The method for manufacturing a microdevice according to claim 7, wherein the first bulk layer and the second bulk layer are single crystal silicon, and the intermediate layer is silicon oxide. Manufacturing method of micro device. 10. The method of manufacturing a microdevice according to claim 9, wherein the substrate is an SOI substrate. 11. The method for manufacturing a microdevice according to claim 7, wherein, when the second bulk layer is processed to form the support portion, the second bulk layer is removed from the second bulk layer. A method of manufacturing a microdevice, which comprises simultaneously forming the functional element.