JP2003340795A - Electrostatic drive type mems element and manufacturing method therefor, optical mems element, optical modulator, glv device and laser display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To flatten a beam composing an electrostatic drive type MEMS element or stabilize and uniformalize a beam shape. <P>SOLUTION: The electrostatic drive type MEMS element comprises a substrate side electrode 33, a beam 36 disposed opposite to the substrate side electrode 33, having a drive side electrode 37 and supported on the both ends thereof, and at least two supporting parts 35A, 35B and 35C, 35D are provided on the both ends of the beam 36 respectively. In the supporting parts 35, the height t1 of the inner supporting parts 35B, 35C is set to be lower than the height t2 of the outer supporting parts 35A, 35D. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an electrostatic drive type ME.
The present invention relates to an MS element and its manufacturing method, an optical MEMS element, a light modulation element, a GLV device, and a laser display.

[0002]

2. Description of the Related Art With the progress of fine technology, a so-called micro machine (MEMS: Micro Electro M) has been developed.
electrical Systems, ultra-small electrical
Attention has been focused on small devices incorporating mechanical composite devices and MEMS devices. The MEMS element is formed as a fine structure on a substrate such as a silicon substrate or a glass substrate, and electrically and mechanically connects a driving body that outputs a mechanical driving force and a semiconductor integrated circuit that controls the driving body. Is a device that is coupled to. A basic feature of the MEMS device is that a driving body configured as a mechanical structure is incorporated in a part of the device, and the driving body is driven by applying a clonal attractive force between electrodes. It is done electrically.

FIG. 16 shows a conceptual structure of a so-called double-supported beam type electrostatically driven MEMS device. The MEMS device 1 includes a substrate 2 and a substrate-side electrode 3 formed on the substrate 2.
And a beam 6 having a driving-side electrode 4 arranged in parallel to face the substrate-side electrode, and a supporting portion 7 for supporting both ends of the beam 6. The beam 6 and the substrate-side electrode 3 are electrically insulated by the gap 8 therebetween.
The substrate 2 is composed of, for example, a semiconductor substrate 9 such as silicon (Si) or gallium arsenide (GaAs) shown in FIG.
A required substrate such as a substrate on which is formed or an insulating substrate such as a glass substrate is used. The substrate-side electrode 3 is formed of a polycrystalline silicon film doped with impurities, a metal film (for example, a tungsten (W) vapor deposition film), or the like. Substrate side electrode 3
An insulating film 11 is formed on the entire surface of the substrate 2 including, and the beam 6 is arranged so as to face the insulating film 11. Beam 6
Is an insulating film 5 such as a silicon nitride film (SiN film).
And a drive-side electrode 4 formed on the upper surface thereof, for example, an Al film having a film thickness of about 100 nm.

FIG. 19 shows a manufacturing process of the MEMS element 1. First, as shown in FIG. 19A, a substrate, for example, a substrate in which an insulating film 10 is formed on the surface of a semiconductor substrate 9 is prepared, and a conductive film is deposited on this substrate 2 and patterned to form a substrate-side electrode 3. Then, the insulating film 11 is deposited on the entire surface. Next, as shown in FIG. 19B, for example, a polycrystalline silicon film to be a sacrificial layer is deposited and patterned to form a sacrificial layer 12 of the polycrystalline silicon film. By this patterning, openings 13 [13A, 13B] are formed in the portions where the beam supporting portions to be described later are to be formed. next,
As shown in FIG. 19C, the sacrificial layer 12 and the opening 13 [1
3A, 13B], an insulating film, for example, a silicon nitride film 5 and an Al film, which serves as a driving side electrode, are stacked over the substrate 2 and patterned into a predetermined beam shape. Next, in the final step shown in FIG. 19D, the sacrificial layer 12 is selectively removed to form the beam 6 that is the MEMS driving portion.
The beam 6 is formed in a two-layer film structure composed of a drive electrode 4 made of a SiN film 5 and an Al film, and is arranged so as to face the substrate 2 with a gap 8 in between, and both ends of the beam 6 are continuous and integrated with the beam 6. The supporting portion 7 [7 having the same two-layer film structure formed on the
A, 7B]. As the material of the sacrificial layer 12, a material having a high etching selectivity with respect to the substrate-side electrode 3, the insulating film 11 and the beam 6 is selected.
Gas etching with F vapor or XeF ₂ gas is effective. A method of forming the sacrificial layer 12 with an oxide film and performing wet etching with a dilute hydrofluoric acid solution is also used. In this way, the both end beam type electrostatically driven ME
The MS element 1 is obtained.

In such a double-supported beam type MEMS device, the mechanical characteristics are determined by the physical size of the beam 6, which is a diaphragm. The width and thickness of the beam 6 are determined by the process, and the distance between the supporting portions 7A and 7B is an important factor due to the structure.

In the MEMS element 1, the beam 6 is displaced by electrostatic attraction or electrostatic repulsion between the substrate-side electrode 3 and the driving-side electrode 4, depending on the potential applied to the substrate-side electrode 3 and the driving-side electrode 4. Are displaced into a parallel state and a concave state with respect to the substrate side electrode 3.

The MEMS element 1 reflects in one direction by utilizing the fact that when the surface of the driving electrode 4 is used as a light reflecting film to irradiate the surface with light, the reflecting direction of the light varies depending on the driving position of the beam 6. It can be applied as an optical switch that detects light and has a switch function. Further, the MEMS element 1 can be applied as a light modulation element that modulates the light intensity. When utilizing the reflection of light, the beam 6 is vibrated to modulate the light intensity by the amount of reflection in one direction per unit time. This light modulation element is what is called time modulation. When utilizing the diffraction of light, a plurality of beams are arranged in parallel with respect to the common substrate side electrode 3 to form a light modulation element, and for example, every other beam is approached or separated from the common substrate side electrode 3. Changes the height of the driving side electrode 4 which also functions as a light reflecting film,
The intensity of light reflected by the driving-side electrode 4 is modulated by the diffraction of light. This light modulation element is what is called spatial modulation.

FIG. 20 shows a GLV (Grating Lig) developed by SLM (Silicon Light Machine) as a light intensity conversion element for a laser display, that is, a light converter.
ght Valve) The structure of a device is shown. In the GLV device 21, as shown in FIG. 20A, a common substrate-side electrode 23 made of a refractory metal such as tungsten or titanium and a nitride film thereof or a polysilicon thin film is formed on an insulating substrate 22 such as a glass substrate. This substrate side electrode 2
6 beams 26 [2
6 ₁ , 26 ₂ , 26 ₃ , 26 ₄ , 26 ₅ , 26 ₆ ] are arranged in parallel. As shown in FIG. 20B, the configuration of the substrate-side electrode 23 and the beam 26 is, for example, a reflective film / driving-side electrode made of an Al film having a film thickness of about 100 nm on the surface of the bridge member 25 made of SiN film in equilibrium with the substrate-side electrode 23. 24
Are formed. A beam 26 including a bridge member 25 and a reflecting film / driving side electrode 24 provided thereon.
Is a part commonly called a ribbon.

In the GLV device 21, the substrate side electrode 23
When a minute voltage is applied between the substrate and the reflecting film / driving side electrode 24, the beam 26 approaches the substrate side electrode 23 due to the electrostatic phenomenon described above, and when the voltage application is stopped, the beam 26 separates from the original state. Return to. Then, the height of the reflective film / driving side electrode 24 is alternately changed by the operation of approaching and separating the plurality of beams 26 with respect to the substrate side electrode 23 (that is, the operation of approaching and spacing apart every other beam), The intensity of the light reflected by the driving-side electrode 24 can be modulated by diffracting the light (one light spot is irradiated on the entire six beams 26).

[0010]

By the way, it is pointed out that relaxation of residual stress of the driving beam 6 is often a problem in the above-mentioned double-supported beam type MEMS element.
Description will be given using the MEMS element 1 having the structure of FIG. Before the sacrificial layer 12 is removed, the structure has a multi-layer structure including the sacrificial layer 12, and the shape of the beam 6, which is a vibrating body, is governed only by the mechanical equilibrium between the films. For example, Al
In the case of the beam 6 having a two-layer structure of / SiN, as shown in FIG. 17, after the sacrifice layer 12 is removed, the supporting portion (so-called support)
It is known that the beam 6 between 7A and 7B has a tendency to be deformed so as to draw an upward arc (illustrated by a solid line).
Further, in this state (state in which the sacrificial layer 12 is removed), annealing is performed. This time, it is easy to understand that it is curved so as to draw a downward arc (illustrated by a broken line).

However, such a beam warp is M
In the EMS device, the support part absorbs everything. Therefore, in a double-supported beam type MEMS element, as shown in FIG. 18, often two columns 15 (four in total) are formed at each end of the beam 6, which is important for the MEMS element. The relative position of is fixed. Here, the outer strut 15A may be named an anchor, the inner strut 15B may be named a post, and the like.

However, it is difficult to use the MEMS element having such accumulated internal strain with high reliability. For example, in the case of having a plurality of beams, each beam shape is not uniform, resulting in poor performance. Further, as shown in FIG. 17, due to the local concentration of stress in the supporting portions 7 [7A, 7B], shape distortion and, if significant, fracture such as cracks may progress in the vicinity of the supporting portions 7.

In view of the above points, the present invention provides an electrostatically driven MEMS device for flattening a beam, stabilizing and uniformizing a beam shape, a method for manufacturing the same, an optical MEMS device, a light modulator, and a GLV. A device and a laser display are provided.

[0014]

SUMMARY OF THE INVENTION An electrostatic drive type MEMS element according to the present invention is a beam which is arranged to face a substrate side electrode and a substrate side electrode, and which has a drive side electrode and is supported at both ends. And at least two supporting portions respectively at both end portions of the beam, of which the height of the supporting portion located inside is set lower than the height of the supporting portion located outside. To do. The beam is driven by an electrostatic attractive force or electrostatic repulsive force that acts between the driving side electrode and the substrate side electrode. The same applies to the beam.

In the electrostatic drive type MEMS element of the present invention, in the initial state (so-called provisionally completed state), the beam is supported only by the outer support portion and not by the inner support portion. The strain is relaxed between the outer support and the outer support. Residual stress or the like does not occur in the beam itself even after the subsequent heat treatment process for the purpose of, for example, uniforming the element performance. The beam is flattened, or the beam shape is stabilized and made uniform by joining or abutting the beam to the inner supporting portion by the first driving in a state where the distortion of the beam is relaxed.

In the method of manufacturing an electrostatic drive type MEMS device according to the present invention, an outer support portion and an inner support portion having a height lower than that of the outer support portion are provided on a substrate having a substrate-side electrode and face each other. The step of forming the supporting part, the step of forming the sacrificial layer so that the supporting part is embedded and the surface of the outer supporting part faces, and the driving side so as to be bonded to the surface of the outer supporting part on the sacrificial layer. The method includes a step of forming a beam having electrodes, a step of removing the sacrificial layer, forming a gap between the substrate-side electrode and the beam, and forming a state in which the beam does not come into contact with the inner supporting portion. Further, the method of manufacturing an electrostatic drive type MEMS device according to the present invention includes a step of forming inner supporting portions facing each other on a substrate on which a substrate-side electrode is formed, and embedding the inner supporting portion on the substrate. And a step of forming a sacrificial layer having a thickness greater than the height of the inner supporting portion by extending to the outside of the inner supporting portions, and the upper and side surfaces of the sacrificial layer,
Further, a step of extending the same material layer on the substrate, patterning the material layer to form a beam having a driving side electrode and an outer supporting portion continuous to the beam, and removing the sacrificial layer Forming a space between the substrate-side electrode and the beam, and forming a state in which the beam does not contact the inner supporting portion.

According to the method of manufacturing an electrostatic drive type MEMS element of the present invention, it is possible to manufacture a MEMS element in which the beam is flattened or the beam shape is stabilized and uniformed.

An optical MEMS element according to the present invention comprises a substrate-side electrode and a beam which is arranged so as to face the substrate-side electrode and which has a driving-side electrode and whose both ends are supported. Each has at least two supporting portions, and the height of the supporting portion located inside of the supporting portions is set lower than the height of the supporting portion located outside of the supporting portion.

In the optical MEMS element of the present invention, in the initial state (so-called temporary completed state), the beam is supported only by the outer supporting portion and is supported by the inner supporting portion, so that the same as above. The distortion of the beam is relaxed between the beam and the outer supporting portion, and no residual stress is generated in the beam even after the subsequent heat treatment process. After that, when the beam is first driven, the beam is joined to or abutted on the inner supporting portion, so that the beam is flattened, or the beam shape is stabilized and uniformed, and the reliability of the optical MEMS element is improved. To do.

An optical modulator according to the present invention comprises a substrate-side electrode and a beam which is arranged so as to face the substrate-side electrode and which has a driving-side electrode and whose both ends are supported. Each has at least two supporting portions, and the height of the supporting portion located inside of the supporting portions is set lower than the height of the supporting portion located outside of the supporting portion.

In the light modulating element of the present invention, in the initial state (so-called provisionally completed state), the beam is supported only by the outer supporting portion and is supported by the inner supporting portion. The distortion of the beam is relaxed between the beam and the outer supporting portion, and no residual stress is generated in the beam even after the subsequent heat treatment process. After that, the beam is flattened or the shape of the beam is stabilized and made uniform by joining or abutting the beam to the inner supporting portion by the first driving of the beam. Therefore, the reliability of the light modulation element is improved.

In the GLV device according to the present invention, a common substrate-side electrode and a common substrate-side electrode are arranged in parallel independently of each other and have a reflective film and a driving-side electrode and both end portions are supported. A plurality of beams, each of which has at least two supporting portions at both end portions, and the height of the supporting portion located inside is lower than the height of the supporting portion located outside. Use the set configuration.

In the GLV device of the present invention, in the initial state (so-called provisionally completed state), the beam is supported only by the outer support portion and by the inner support portion. The strain is relaxed between the outer supporting portion and the outer supporting portion, and no residual stress is generated in the beam even after the subsequent heat treatment process. After that, when the beam is first driven, the beam is joined to or abuts on the inner supporting portion, so that the beam is flattened, or the beam shape is stabilized and uniformed, and the uniformity of the dark level is improved. Improves device reliability.

A laser display according to the present invention is a laser display having a laser light source and a GLV device arranged on the optical axis of the laser light emitted from the laser light source and modulating the light intensity of the laser light. , GLV
The device includes a common substrate-side electrode, and a plurality of beams that are arranged in parallel independently of each other so as to face the common substrate-side electrode, have a reflecting film and a driving-side electrode, and are supported at both ends thereof. At least two support portions are provided at both end portions of each beam, and the height of the support portion located on the inner side of the support portions is set lower than the height of the support portion located on the outer side.

In the laser display of the present invention, in the GLV device for modulating the light intensity of the laser beam, in the initial state (so-called temporary completion state), the beam is supported only on the outer supporting portion and on the inner supporting portion. As described above, the beam is strain-relieved between itself and the outer supporting portion, and no residual stress is generated in the beam even after the subsequent heat treatment process. The beam joins or abuts the inner supporting portion to flatten the beam image or stabilize and uniformize the beam shape, thereby improving the uniformity of the dark level. Therefore, the reliability of the laser display is improved.

[0026]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an electrostatically driven MEMS according to the present invention.
1 illustrates a representative embodiment of a device. The MEMS element 31 according to the present embodiment has a substrate-side electrode 33 formed on a substrate 32, an insulating film 34 formed on the entire surface of the substrate 32 including the substrate-side electrode 33, and a substrate on the insulating film 34. Side electrode 3
A plurality of supporting portions 35 [35A, 35B, 35C, 35D] are formed so as to be opposed to each other with 3 in between,
An electrostatically driven beam 36 having both end portions supported by a support portion 35 so as to face the substrate-side electrode 33 via a gap 50.
It is configured by arranging.

In the present embodiment, in particular, of the support portions 35, the support portions (posts: anchors) 3 located on the outer side.
5A and 35D are formed to be high, and support portions (posts called posts) 35B and 35C located inside are formed on the outside support portion 3
5A and 35D are formed to have a height t ₁ lower than the height t ₂ , and in the initial state, that is, in the temporarily completed state, both end portions of the beam 36 have outer support portions 35A and 35A.
The beam 36 is supported by D and is configured so that the beam 36 does not contact the inner supporting portions 35B and 35C. Beam 36
It is configured as a so-called double-supported beam type. The semiconductor integrated circuit or the like for controlling the driving of the MEMS element 31 is the same substrate 3
2 may be incorporated, or it may be mounted on an IC chip electrically connected.

The substrate 32 is made of silicon (Si) or gallium.
Form an insulating film on a semiconductor substrate such as arsenic (GaAs)
Required substrate such as insulating substrate such as transparent substrate and glass substrate
Is used. In this example, on the silicon single crystal substrate 39
Silicon oxide film (SiO₂Substrate 32 on which film 40 is formed
Was used. The substrate-side electrode 33 is made of impurities
Crystal silicon film, metal (eg tungsten (W) deposition)
Film) or the like. Insulating film 34 covering the substrate-side electrode 33
Is, for example, a silicon oxide film (SiO₂Formed)
It The beam 36 is, for example, a silicon nitride film (SiN
Film), silicon oxide film (SiO ₂Insulating film such as film), this example
Then, the physical properties such as elastic constants are
Appropriate silicon nitride film 38 and the driving side electrode 3 thereon
7 and a laminated film. As the driving side electrode 38,
Ag film, Al film mainly composed of aluminum Al, or
Is titanium Ti, tungsten W, molybdenum Mo, tan
It is possible to use any refractory metal such as Tal Ta.
it can. In this example, it is an Al film having a film thickness of about 100 nm.
The driving side electrode 37 is used.

The supporting portion 35 can be formed of, for example, a polysilicon film whose surface is oxidized, or an appropriate insulating film such as a silicon nitride film or a silicon oxide film. Support part 35
The shape may be, for example, a round shape, a rectangular shape, or any other shape as long as the shape viewed from above is not an extreme shape in which the beam 36 is distorted by the joining or abutting of the beam 36.

3 to 6 show the above electrostatically driven MEMS.
An embodiment of a method for manufacturing the element 31 will be described. First, FIG.
As shown in A, a substrate 32 in which a silicon oxide film (SiO ₂ film) 40 is formed on a required substrate, in this example, a silicon single crystal substrate 39, is prepared, and a photolithography technique is used on the silicon oxide film 40. Substrate-side electrode 33 made of, for example, an impurity-doped polycrystalline silicon film or metal
To form. Next, an insulating film having a desired film thickness, in this example, a silicon oxide film (SiO ₂ film) 34 is formed on the entire surface of the substrate 32 including the substrate-side electrode 33.
On the upper side, material layers corresponding to the shape of a pair of first supporting portions, that is, inner pillars (so-called posts) 35B and 35C are formed at positions corresponding to the outer sides of both ends of the substrate-side electrode 33 so as to face each other. In this example, the polycrystalline silicon film 4 is used as the material layer.
2, using the photolithography technique, the support 35
Patterning is performed in the shapes of B and 35C to form a pillar-shaped polycrystalline silicon film 42.

Next, as shown in FIG. 3B, the surface of the pillar-shaped polycrystalline silicon film 42 is thermally oxidized, and finally the pillar having a height t ₁ having the surface oxide film 43 on the polycrystalline silicon film 42. 35B and 35C are formed.

Next, as shown in FIG. 4C, a material layer to be the second support portion, that is, an outer pillar (so-called anchor) higher than the height t _{1 of the} inner pillars 35B and 35C is deposited. In this example, as the material layer, a polycrystalline silicon film 44 having a required film thickness thicker than the height t ₁ of the inner pillars 35B and 35C is deposited.

Next, as shown in FIG. 4D, polycrystalline silicon
The film 44 is supported on the outer side by using photolithography technology.
Pattern the pillars 35A and 35D into the shape of the inner support
The pillar-shaped polycrystalline silicon is provided outside the pillars 35B and 35C, respectively.
The con film 44 is formed. Next, the pillar-shaped polycrystalline silicon
The surface of the con film 44 is thermally oxidized and finally polycrystalline silicon
The film 44 has a surface oxide film 45, and the inner column 35
Height t of B and 35C ₁Higher than, height t₂(T₂>
t₁) Support columns 35A and 35D are formed.

Next, as shown in FIG. 5E, a sacrificial layer 47 to be subsequently removed is deposited on the entire surface so as to fill the inner and outer columns 35B, 35C and 35A, 35D, and then etched back. Or CMP (Chemical
Mechanical Polish: Chemical mechanical polishing)
Then, the sacrificial layer 47 is attached to the pillars 35A and
It is flattened so that it is flush with the surface of D. Then, a material layer to be a beam is deposited on the surface of the sacrificial layer 47 so as to be bonded to the surfaces of the outer columns 35A and 35D, and this material layer is patterned into a beam shape to form the beam 36. In this example, a silicon nitride film (SiN
A two-layer film consisting of a film 38 and an Al film 37 thereon is deposited and patterned to form an electrostatically driven beam 36 using the Al film 37 as a driving side electrode. The material of the sacrificial layer 47 is selected to have high etching selectivity with respect to the substrate-side electrode 33 and the beam 36. In this example, the polycrystalline silicon film is used as described above.

Next, as shown in FIG. 5F, the sacrificial layer 47 is selectively removed. In this example, since the polycrystalline silicon film is used as the sacrificial layer 47, hydrofluoric acid (HF) vapor,
Gas etching is more effective than XeF ₂ gas. When a silicon oxide film is used as the sacrificial layer 47, a method of wet etching with a dilute hydrofluoric acid solution is also used. This sacrificial layer 47
As shown in the plan view of FIG. 6 and the cross-sectional view of FIG. 7, for example, when the beams 36 are formed so as to be arranged in plural, the etching gas 49 or the etching gas 49 from the gap 48 between the adjacent beams 36 or An etching solution is introduced and removed by etching. 5F corresponds to the cross-sectional view taken along the line AA of FIG. 6, and FIG. 7 corresponds to the cross-sectional view taken along the line BB of FIG. In this way, the temporarily completed MEMS element 31 is obtained. That is, the beam 36 having the driving-side electrode 37, which is arranged so as to face the substrate-side electrode 33 via the gap 50.
Both ends of the column are joined to the outer columns 35A and 35D, and the beam 36 does not contact the inner columns 35B and 35C.

In the temporarily completed MEMS element 31 according to this embodiment described above, the beam 36 has its strain relaxed between the outer columns 35A and 35D. For example, even if a heat treatment process such as aging is performed for the purpose of making the element characteristics uniform, the structure is relaxed between the outer columns 35A and 35D that are currently joined to form a vibration plate. Residual stress or the like does not occur in the beam 36 itself. When the use of the MEMS element 31 is started, the first electric field is applied between the substrate side electrode 33 and the driving side electrode 37 of the beam 36. The beam 36 is pulled downward by the Coulomb force, but at this time, the beam 36 comes into contact with the inner columns 35B and 35C. Let the electric field at this time be α. Beam 36 with inner support 35B
And 35D, an oscillating electric field X for vibrating the beam 36 is applied between the substrate-side electrode 33 and the driving-side electrode 37. Beam 36 includes inner struts 35B and 35
It vibrates on the basis of the contact surface of C.

The MEMS element 31 according to the present embodiment is
There are two ways to use it. The first method of use is to apply the first electric field α to bring the beam 36 into contact with the inner columns 35B and 35C, thereby joining the beam 36 and the inner columns 35B and 35C. This is a case where the beam 36 and the inner columns 35B and 35C are not separated from each other even when the switch is turned off (when the so-called element 31 is stopped), and the bonded state is continuously maintained. That is, the MEMS element 31 is used in a state in which the beam 36 is maintained in the form of FIG. 2 in which the beam 36 is joined to the inner columns 35B and 35C. In this way, the beam 36 and the inner columns 35B and 35C are subjected to the first electric field α.
In order to join the
For example, if the abutting surfaces of the two are mirror-finished, it becomes difficult for them to be separated by the intermolecular force after the abutting. The second usage is that the beam 36 is not joined to the inner columns 35B and 35C, but the beam 36 is brought into contact with the columns 35B and 35C by the application of the electric field α and the electric field α is turned off. And 35C and the case of returning to the state of FIG. In order to bring the beam 36 into contact with the struts 35B and 35C when in use and separate it from the struts 35B and 35C when not in use, the interface state between them should be controlled, for example, by making one or both abutting surfaces rough. It becomes easy to separate.

When the MEMS element 31 is operated, the driving electric field is different depending on the above two usage methods. In the non-use state (at the time of stop), the MEMS element 31 having the configuration of FIG. 1 is driven by applying the drive voltage X + α (X> 0) between the drive side electrode 37 of the beam 36 and the substrate side electrode 33. The contact voltage α causes the beam 36 to contact the columns 35B and 35C, and the vibration voltage X causes the beam 36 to vibrate toward the substrate-side electrode 33 with reference to the contact surfaces of the columns 35B and 35C.
On the other hand, in the case of the MEMS element 31 having the configuration of FIG. 2 in the non-use state (at the time of stop), the drive side electrode 37 of the beam 36.
A driving voltage (so-called vibration voltage) X is applied between the substrate and the substrate-side electrode 33 for driving. In this case, the value of X can be selected not only by the attractive force toward the substrate-side electrode 33 but also by the polarity such that the repulsive force acts.

The MEMS element 3 according to the above-mentioned present embodiment
According to 1, the beam 36 has the inner support column 3 in the temporarily completed state.
5B and 35C are not joined or abutted, and the beam 36 is joined or abutted to the inner columns 35B and 35C in a use state. Therefore, the beam 36 is not in contact with the inner columns 35B and 35C. At this time, the distortion of the beam 36 during processing is relaxed, and the inner support column 3 during use
The beam 36 is flattened when it is joined to or abutted on 5B and 35C. That is, after the beam 36 is freely distorted in the state shown in FIG. 1, the beam 36 is joined to or abuts on the support columns 35B and 35C, so that the beam 36 is supported by the inner support columns 35B and 35C in a state where the distortion is relaxed. In the present embodiment, when a plurality of beams 36 are arranged, the beam shape of each beam 36 can be made uniform. M
In the EMS element 31, it is possible to avoid deterioration of element characteristics due to residual stress of the beam 36, and it is possible to provide a more reliable electrostatic drive type MEMS element.

In the MEMS element, fluctuations exist at the interface between the beam and the supporting portion. The uniformity of the height of the beam and the supporting surface is determined in the manufacturing process, and the fluctuation amount is determined by a number of parameters such as film thickness uniformity and processing variation in the film forming process, and the distribution of crystal grains. . In the case of a pillar structure, there are fluctuation factors at two places, an upper part connected to the beam and a lower part connected to the substrate. By reducing the number of fluctuation parameters existing at the interface between the beam and the supporting portion, the fluctuation factor can be reduced. In the above-described present embodiment, since the beam whose strain has been relaxed is joined or abutted to the inner column, the fluctuation existing at the vibration reference position of the beam (that is, the interface with the inner column) is eliminated. Significantly reduced, that is, the fluctuation is uniform, and ME
The characteristics of the MS element are improved.

As mentioned above, M which utilizes mechanical vibration
In the EMS device, residual structural strain depending on the manufacturing process, such as between the beam and the supporting column, is a serious problem from the viewpoint of device performance. In the present embodiment, after the beam is mechanically opened through the sacrificial layer removing step, the relative positions of the beam and the column can be fixed within the range of processing accuracy. Specifically, in the present embodiment, the beam and the pillar are bonded to each other, which has been performed in the conventional bulk body state, after the sacrifice layer is removed in the present embodiment. As a result, the effects described above are obtained. The beam and the inner support may be brought into physical contact with each other, or may be electrically operated when driven by an electric field.

In the above structure, the ME fixed to the beam 36 of FIG. 2 in a state of being joined to the columns 35B and 35C.
In the case of the MS element 31, for example, since the environment cools when going from a warm place to a cold place, the beam 36 supported by the column 35 is used.
There is a possibility that the amount of stress inherent in the beam changes, and the beam 36 once relaxed in a warm place is distorted. Therefore,
The beam 36 is output when the standby mode is set according to the environment, the drive is performed at the voltage X + α, and the drive voltage X + α is completely turned off.
The structure in which the columns are separated from the columns 35B and 35C to be in the standby state, that is, the structure in FIG. 1 (the structure in which the state in FIG. 1 and the state in FIG. 2 are repeated) relaxes the strain generated during processing and occurs in the environment. It is more preferable because the strain can be relaxed.

8 to 11 show another embodiment of the MEMS device according to the present invention. The MEMS element 61 of FIG.
Is provided with six struts 35, and in the temporary completion, two struts 35 each serving as an outer anchor on each of the left and right sides.
This is a case where the A, 35A 'and the struts 35D, 35D' are joined to the beam 36, and the beam 36 is separated from the struts 35B, 35C to be the inner posts. Since other configurations are the same as those in FIG. 1, parts corresponding to those in FIG. Also in the MEMS element 61 according to the present embodiment, the same usage as in FIGS. 1 and 2 can be adopted, and the MEMS element 3 described above is used.
The same action and effect as 1 are achieved.

The MEMS element 62 of FIG.
In the provisional completion, the columns 35A and 35D, which are the left and right outer anchors, are joined to the beam 36, and the two columns 35B and 35 are the inner posts.
This is the case in which the beam 36 is separated from B'and the columns 35D and 35D '. Since other configurations are the same as those in FIG. 1, parts corresponding to those in FIG. MEMS element 6 according to the present embodiment
Also in 2, it is possible to adopt the same method of use as in FIG. 1 and FIG. 2, and to obtain the same operation and effect as the above-described MEMS element 31.

The MEMS element 63 of FIG. 10 is provided with six columns 35, and when provisionally completed, columns 35A and 35D, which are the anchors on the left and right sides, are joined to the beam 36 to form the inner posts. Two columns 35B, 35
B 'and struts 35C, 35C' so that the height decreases toward the respective sequential inward (t _1> t ₁ ') is formed,
This is a case in which the beam 36 is separated from the columns 35B and 35B 'and the columns 35C and 35C'. Since other configurations are the same as those in FIG. 1, parts corresponding to those in FIG. The MEMS element 63 according to the present embodiment can also be used in the same manner as in FIGS. 1 and 2, and can achieve the same actions and effects as those of the MEMS element 31 described above.

The MEMS element 64 of FIG. 11 has a beam 36 of the same two-layer film structure as described above, which faces the substrate-side electrode 3 so as to be separated from the posts 35B and 35C on the inner side, which are post-finished. Strut portions 66A and 66D having a height t ₂ located outside the columns 35B and 35C and extending from the beam 36, and extension portions 67A. 6
This is a case where 7D is formed and configured. In this configuration, the pillars 66A on the outer side and the extension 67A on the insulating film 34, and the pillar 66D and the extension 67D on the insulating film 34 form pillars 68A and 68D serving as anchors, respectively. Since other configurations are the same as those in FIG. 1, parts corresponding to those in FIG. The MEMS element 63 according to the present embodiment can also be used in the same manner as in FIG. 1 and FIG.
The same action and effect as the element 31 are obtained.

The MEMS device 6 of FIGS. 8 to 10 described above.
With respect to 1, 62 and 63, in the case of a MEMS element using a beam having a large tension, a combination as shown in FIGS. 8 to 10 is selected as a combination of columns. These choices depend on the flatness required of the beam,
Due to the trade-off of adhesion between beam / support / substrate
The optimum one should be selected. On the other hand, FIG.
In the MEMS device 64, the structure in which the manufacturing process can be simplified by using the outer support pillar also as the adhesion layer with the substrate.

12 to 13 show the above electrostatically driven ME.
An embodiment of a method for manufacturing the MS element 64 will be described. First, as shown in FIG. 12A, a required substrate, in this example, a substrate 32 in which a silicon oxide film (SiO ₂ film) 40 is formed on a silicon single crystal substrate 39 is prepared, and photolithography is performed on the silicon oxide film 40. A substrate-side electrode 33 made of, for example, an impurity-doped polycrystalline silicon film or a metal is formed by using a technique. Next, the substrate 3 including the substrate-side electrode 33
An insulating film having a required film thickness, which is a silicon oxide film (SiO ₂ film) 34 in this example, is formed on the entire surface of No. ₂ and is formed on the silicon oxide film 34 at positions corresponding to the outer sides of both ends of the substrate side electrode 33. Inner columns 35B facing each other to form a pair of posts
And 35C are formed. In this example, similarly to the above, using the polycrystalline silicon film 42, patterning into the shapes of the pillars 35B and 35C by using the photolithography technique,
A pillar-shaped polycrystalline silicon film 42 is formed. Then
The polycrystalline surface of the silicon film 42 of the pillar shape is thermally oxidized to form a final polycrystalline silicon film 42 on the surface oxide film 43 height t ₁ having an inner post 35B and 35C.

Next, as shown in FIG. 12B, the insulating film 34
Supports 35B and 34 including support 35B and 35C on top
5C is patterned to reach the outside of the pillar 5B.
And the sacrificial layer 47 having a film thickness t ₂ thicker than the height t _{1 of} 35C.
To form.

Next, as shown in FIG. 13C, the sacrificial layer 47.
A two-layer film, for example, a silicon nitride film (SiN film) 38 serving as a beam and an Al film 37 formed thereon is deposited and patterned on the entire surface including the upper surface and side surfaces of the Al film 37 and the upper surface of the insulating film 34, and the Al film 37 is patterned. To form an electrostatically driven beam 36 having a drive side electrode. At this time, at the same time, the outer columns 68A and 68D having a height t ₂ are formed at both ends of the beam 36 and are composed of the column portions 66A and 67A which are integral with the beam 36 and the extension portions 67A and 67D which crawl on the insulating film 34.

Next, as shown in FIG. 13D, the sacrificial layer 47.
Is removed by gas etching with, for example, hydrofluoric acid (HF) vapor or XeF ₂ gas.
The MS element 64 is obtained.

When the MEMS element according to this embodiment described above is applied to an optical MEMS element, a beam 36 having a stable beam shape, that is, a flattened beam 36 can be formed, so that a stable ON, It is possible to improve the performance as an optical element such as an optical switch that can be turned off, a high frequency switch, and an optical modulator that modulates the light intensity. The high frequency switch is applied to millimeter-wave and microwave transmission wiring switches and the like. In this high-frequency switch, a MEMS element serving as a switch plate is arranged between the input section and the output section, and the MEMS element is vertically moved to electrically contact or non-contact the input section and the output section to conduct or non-conduct. Is configured to obtain. Since the MEMS element moves mechanically,
Very small switches can be constructed.

The MEMS element according to the present embodiment described above can be applied to a driving portion of a driving device for a microfluid such as liquid or gas. For example, a beam of a MEMS element is used as a diaphragm, a chamber for accommodating a microfluid such as a liquid or a gas is arranged on the beam, a nozzle portion is provided in the chamber, and a liquid supplied into the chamber is driven by the MEMS element. It is possible to configure a device that ejects a microfluid such as a gas or a gas from the nozzle portion.

FIG. 14 shows an embodiment of a GLV device according to the present invention. The GLV device 71 according to the present embodiment is similar to the common substrate-side electrode 73 formed on the substrate-side electrode 72 in the same manner as described above with reference to FIGS. 1 and 2.
Supports 75A, 75D and supports 75B, 75 with different heights
C, and in the state of temporary completion, the outer columns 75A and 75
The beam is joined to D, and the beam is separated from the inner columns 75B and 75C.
[76 ₁ , 76 ₂ , 76 ₃ , 76 ₄ , 76 ₅ , 76 ₆ ]
Are arranged in parallel. GLV71 of the present embodiment
In the same manner as described above, the height of the drive-side electrode 77 that also functions as a light-reflecting film is alternately changed by the operation of approaching and separating every other beam 76 from the substrate-side electrode 73, and the drive-side is driven by the diffraction of light. The intensity of light reflected by the electrode 77 is modulated.

According to the GLV device 71 according to this embodiment, the shapes of the beams 76 can be made uniform.
It is possible to provide a high performance GLV device with improved dark level uniformity.

FIG. 15 shows the MEMS according to the present embodiment described above.
An embodiment of an optical apparatus using a GLV device as a light modulation element to which the element is applied is shown. In this example, it is applied to a laser display. The laser display 81 according to the present embodiment is used, for example, as a large screen projector, especially as a digital image projector, or as a computer image projection device.

As shown in FIG. 15, the laser display 81 includes laser light sources 82R, 82G, and 82B of red (R), green (G), and blue (B) colors, and lights for the respective laser light sources. Mirrors 74R, which are sequentially provided on the axis,
84G, 84B, each color illumination optical system (lens group) 86R,
86G, 86B, and GLV functioning as an optical modulator
The devices 88R, 88G, and 88B are provided. The laser light sources 82R, 82G, 82B are, for example, R
(Wavelength 642nm, light output medicine 3W), G (wavelength 532n
m, light output about 2 W), and B (wavelength 457 nm, light output about 1.5 W).

Further, the laser display 81 is a GLV.
A color synthesizing filter 90, a spatial filter 92, a diffuser 94 for synthesizing the red (R) laser light, the green (G) laser light, and the blue (B) laser light whose light intensities are respectively modulated by the devices 88R, 88G, and 88B. Mirror 8
6, galvano scanner 98, projection optical system (lens group) 1
00 and a screen 102. The color synthesis filter 90 is composed of, for example, a dichroic mirror.

Laser display 81 of the present embodiment
R, G, and B laser beams emitted from the laser light sources 82R, 82G, and 82B are mirrors 84R, 84G, and
After passing through 84B, they enter the respective GLV devices 88R, 88G and 88B from the respective color illumination optical systems 86R, 86G and 86B. Each laser light is a color-classified image signal, and GL
The V devices 88R, 88G, and 88B are synchronously input. Further, the respective laser lights are spatially modulated by being diffracted by the GLV devices 88R, 88G, 88B, and the diffracted lights of these three colors are combined by the color synthesis filter 9.
0, and then the spatial filter 92 extracts only the signal component. Next, laser speckles are recommended for the RGB image signals by the diffuser 84, the mirror image is passed through the mirror 96, the galvano scanner 98 synchronized with the image signals is developed into space, and the projection optical system 100 forms a full-color image on the screen 102. Projected.

Since the laser display 81 of the present embodiment is provided with the GLV devices 88R, 88G and 88B having the structure shown in FIG. 14 as the light modulation element, the dark level uniformity can be obtained and the conventional light modulation element can be used. The quality is improved compared to the conventional laser display.

The laser display 81 of the present embodiment is provided with GLV devices 88R, 88G and 88B corresponding to the laser light sources 82 of the respective colors, but the GLV device according to the present invention has a configuration other than this. It is also applicable to various displays. For example, while the light source is white, the light modulation elements 88R, 88G, and 88B having different beam widths are provided so that only the lights of the respective wavelengths of RGB are reflected (the other lights are diffracted) to display the respective colors.
May form one pixel. Further, white light from a single light source can be made incident on the GLV device 88 through a color wheel synchronized with image information composed of RGB image data. Further, for example, using a single GLV device 88, RGB LE
If the light from the D (light emitting diode) is diffracted and the color information for each pixel is reproduced, a simple handy type color display can be obtained.

Further, the GLV device according to the present invention is not limited to projectors such as the laser display of the present embodiment, but also WDM (Wavelen) in optical communication.
gth Division Multiplexing:
Various devices for wavelength multiplexing) transmission, MUX (Multi)
Plexer: Parallel-to-serial converter / distributor, or OADM (Optical Add / D)
rop Multiplexer), OXC (Opti
It can also be used as an optical switch such as a cal cross connect). Further, it can be applied to other optical devices such as a fine drawing device capable of directly drawing a digital image, a semiconductor exposure device, a printer engine, and the like.

Further, in the laser display 81 of the present embodiment, the laser display in which the spatial modulation is performed by using the GLV devices 88R, 88G and 88B has been described. However, the GLV device according to the present invention has a phase, a light intensity and the like. Information that can be modulated by interference / diffraction can be switched, and it can be applied to an optical device using these.

When the MEMS element according to this embodiment described above is applied to an optical MEMS element whose beam (ribbon) surface which is applied to an optical switch, an optical modulator, a GL device, a laser display and the like also serves as a light reflecting surface, The light utilization factor can be improved by ensuring that the surface is parallel to the substrate for the entire beam surface.

[0066]

According to the electrostatic drive type MEMS element of the present invention, the strain accumulated in the laminated structure during the manufacturing process is alleviated, and the beam of the beam is bonded in the state of being bonded to or abutted on the inner supporting portion. Since the flattening is performed or the beam shape is stabilized and made uniform, the performance as the MEMS element can be improved. Electrostatic drive type MEMS according to the present invention
According to the element manufacturing method, the above-described MEMS element can be manufactured accurately and easily.

The electrostatic drive type MEMS element of the present invention is used as an optical element M.
When applied to an EMS element, the beam is flattened, or the beam shape is stabilized and uniformed.
The performance as an optical MEMS element can be improved. When the electrostatic drive type MEMS device of the present invention is applied to a light modulation device utilizing reflection or diffraction of light, the beam is flattened, or the beam shape is stabilized and uniformed. The performance as an element can be improved.

When a GLV device is constituted by the light modulation element of the present invention, it is possible to provide a GLV device having improved dark level uniformity and improved performance. When incorporating the GLV device of the present invention into a laser display, a laser display with improved performance can be provided.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of an electrostatic drive type MEMS device according to the present invention.

2 is a configuration diagram showing one usage state of the electrostatic drive type MEMS element of FIG. 1. FIG.

3A to 3B are process drawings (No. 1) showing an embodiment of a method of manufacturing an electrostatic drive type MEMS device according to the present invention.

4A to 4D are process diagrams (2) showing the embodiment of the method of manufacturing the electrostatic drive type MEMS device according to the present invention.

5A to 5F are process diagrams (No. 3) showing the embodiment of the method of manufacturing the electrostatic drive type MEMS device according to the present invention.

FIG. 6 is a plan view of an essential part for explaining the MEMS element according to the present embodiment.

FIG. 7 is a cross-sectional view of an essential part for explaining the MEMS element according to the present embodiment.

FIG. 8 is a configuration diagram showing another embodiment of the electrostatic drive type MEMS element according to the present invention.

FIG. 9 is a configuration diagram showing another embodiment of the electrostatically driven MEMS device according to the present invention.

FIG. 10 is a configuration diagram showing another embodiment of the electrostatic drive type MEMS element according to the present invention.

FIG. 11 is a configuration diagram showing another embodiment of the electrostatically driven MEMS device according to the present invention.

12A to 12C are process diagrams (No. 1) showing the embodiment of the method for manufacturing the electrostatic drive type MEMS device of FIGS.

13A to 13D are process diagrams (No. 2) showing the embodiment of the method for manufacturing the electrostatic drive type MEMS device of FIGS.

FIG. 14 A is a configuration diagram showing an embodiment of a GLV device according to the present invention. B is a cross-sectional view of FIG. 14A.

FIG. 15 is a configuration diagram showing an embodiment of a laser display according to the present invention.

FIG. 16 is a configuration diagram showing an example of a conventional electrostatic drive type MEMS element.

FIG. 17 is a cross-sectional view for explaining a problem of a conventional electrostatic drive type MEMS device.

FIG. 18 is a configuration diagram showing a comparative example of an electrostatic drive type MEMS device.

19 is a conventional electrostatic drive type MEMS of FIGS.
FIG. 7 is a process drawing that shows the manufacturing method of the element.

FIG. 20 is a configuration diagram showing a conventional GLV device.

[Explanation of symbols]

3161, 62, 63, 64 ... MEMS element, 32
... Substrate, 33 ... Substrate side electrode, 34 ... Insulating film, 35 [35A, 35B, 35C, 35D] ... Support part, 36 ... Beam, 37 ... Drive side electrode, 38
... Insulating film, 42, 44 ... Polycrystalline silicon film, 4
3, 45 ... Surface thermal oxide film, 47 ... Sacrificial layer, 50
... Void, 71 ... GLV device, 72 ... Substrate, 73 ... Substrate side electrode, 76 [76 ₁ , 76 ₂ , 7
6 ₃ , 76 ₄ , 76 ₅ , 76 ₆ ] ... beam, 77 ...
..Drive side electrodes, 78 ... Insulating film, 81 ... Laser display, 82 [82R, 82G, 82B] ...
Laser light source, 84 [84R, 84G, 84B], 96.
..Mirror, 86 [86R, 86G, 86B] ... Illumination optical system, 88 [88R, 88G, 88B] ... GL
V device, 90 ... Color synthesis filter (die quick mirror), 92 ... Spatial filter, 94 ... Diffuser, 96 ... Mirror, 98 ... Galvano scanner, 100 ... Projection optical system, 102 ... screen

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H01S 3/101 H01S 3/101 H02N 1/00 H02N 1/00 F term (reference) 2H041 AA23 AB38 AC06 AZ01 AZ08 5F072 FF08 JJ01 KK05 MM03 MM07 MM12 RR03 TT13 YY20

Claims (10)

[Claims] 1. A substrate-side electrode, and a beam which is disposed so as to face the substrate-side electrode and has a driving-side electrode and whose both ends are supported, and at least two supports are provided at both ends of the beam. An electrostatic drive type MEMS element, characterized in that a height of an inner supporting portion of the supporting portion is set lower than a height of an outer supporting portion of the supporting portion. 2. The electrostatic drive type MEMS device according to claim 1, wherein the beam is bonded to the inner supporting portion by the first driving of the beam. 3. The static discharge device according to claim 1, wherein the beam abuts on the inner support portion during operation, and the beam separates from the inner support portion during non-operation. Electric drive type MEMS device. 4. The electrostatically driven type according to claim 3, wherein an operating potential based on a contact potential with which the beam is brought into contact with the inner supporting portion is applied to the beam during operation. MEMS device. 5. A step of forming, on a substrate on which a substrate-side electrode is formed, an outer supporting portion and an inner supporting portion having a height lower than that of the outer supporting portion, the supporting portions being opposed to each other, respectively. Forming a sacrificial layer so as to be embedded and exposed to the surface of the outer supporting portion; and forming a beam having a driving side electrode on the sacrificial layer so as to be bonded to the surface of the outer supporting portion, Removing the sacrificial layer, forming a gap between the electrode on the substrate side and the beam, and forming a state in which the beam does not come into contact with the inner supporting portion. Drive-type MEMS device manufacturing method. 6. A step of forming inner supporting portions facing each other on a substrate on which a substrate-side electrode is formed; and embedding the inner supporting portions on the substrate and extending to the outside of both inner supporting portions. Forming a sacrificial layer having a thickness larger than the height of the inner supporting part, and extending the sacrificial layer on the upper surface and the side surface of the sacrificial layer, and further on the substrate to form the same material layer. Patterning to form a beam having a driving-side electrode and an outer supporting portion continuous with the beam, and removing the sacrificial layer to form an air gap between the substrate-side electrode and the beam. And a step of forming a state in which the beam does not come into contact with the inner supporting portion, the method of manufacturing an electrostatic drive type MEMS element. 7. A substrate-side electrode, and a beam that is disposed so as to face the substrate-side electrode and has a driving-side electrode and both ends thereof are supported, and at least two supports are provided at both ends of the beam. An optical MEMS element having a portion, in which the height of the inner supporting portion is set lower than the height of the outer supporting portion. 8. A substrate-side electrode, and a beam that is disposed so as to face the substrate-side electrode and has a driving-side electrode and both ends thereof are supported, and at least two supports are provided at both ends of the beam. A light modulation element, characterized in that it has a portion, and the height of the inner supporting portion of the supporting portion is set lower than the height of the outer supporting portion. 9. A common substrate-side electrode, and a plurality of beams which are arranged in parallel independently of each other so as to face the common substrate-side electrode and which have a reflective film / driving side electrode and whose both ends are supported. And at least two supporting portions at both ends of each beam, wherein the height of the inner supporting portion is lower than the height of the outer supporting portion. GLV device. 10. A laser display having a laser light source and a GLV device arranged on the optical axis of the laser light emitted from the laser light source and modulating the light intensity of the laser light, wherein the GLV device comprises: A common substrate-side electrode, and a plurality of beams that are arranged in parallel independently of each other so as to face the common substrate-side electrode and have a reflective film / driving-side electrode and both end portions thereof are supported; A laser display characterized in that at least two supporting portions are provided at both end portions of the beam, and the height of the inner supporting portion is set lower than the height of the outer supporting portion among the supporting portions.