JP2007178882A - Micro electromechanical device, electronic device, and method of manufacturing micro electromechanical device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce scattered light in a micro electromechanical device for optics. <P>SOLUTION: The micro electromechanical device 1 is so composed to have an optical element 4 having a supporting part 6 connected to a substrate 2 and a modulating part 5 facing the substrate across the supporting part 6, wherein the optical element 4 has a reflecting film 52 at least in the modulating part 5 and the reflecting films 52 and 62 are partially covered by an anti-reflection film 63. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a microelectromechanical device, an electronic device having the microelectromechanical device, and a method of manufacturing the microelectromechanical device.

As a three-dimensional structure formed by a processing technique in semiconductor manufacturing, for example, a micro-processing technique such as photolithography or etching, a so-called micro electro mechanical system (MEMS) is known.
This microelectromechanical device is smaller than conventional general mechanical devices, can easily drive moving parts, and is less likely to cause variations in shape and characteristics due to manufacturing using semiconductor processing technology. With its excellent characteristics, various applications are expected.

In particular, an optical element that forms desired output light by light modulation or optical path regulation is required to have high-speed response in driving and precise optical characteristics. Interest is growing.
As an optical element by a micro electro mechanical device, in addition to a micro mirror, a micro lens, and the like, a device (mechanical grating) that can generate and control diffracted light by a reflective film provided on the surface of a modulation unit that is electrostatically driven. Device) and researches are being made in various fields such as image processing, screen display, optical calculation, and optical printing (see, for example, Patent Documents 1 to 4).

FIG. 9A shows the configuration of this conventional mechanical grid type microelectromechanical device. The microelectromechanical device 101 is provided with a lower electrode 103 on the surface of a substrate 102, a support unit 106 that is at least electrically separated from the lower electrode 103 and connected to the substrate 102, and the support unit 106. A so-called beam-shaped optical element 104 having a modulation unit 105 facing the substrate 103 is provided.
In this micro electro mechanical device 101, the modulation unit 105 and the support unit 106 constituting the optical element 104 have a common structure formed by dielectric films 151 and 161 and reflection films 152 and 162 serving as upper electrodes facing the lower electrode 103. The modulation unit 105 is defined by a support unit 106 at a predetermined height position from the substrate 102 and the lower electrode 103, and the optical element 104 straddles the lower electrode 103. ing.

In this microelectromechanical device 101, the reflective film 152 constituting the modulation unit 105 serving as the upper drive side electrode is electrostatically attracted to the lower electrode 103 on the substrate side in accordance with the potential applied between both electrodes. Or it displaces by electrostatic repulsion, and it displaces in the parallel state and dent state (dashed line illustration) in FIG. 9A.
That is, when a predetermined voltage is applied between the beam-shaped optical element 104 and the lower electrode 103, the height of the modulation unit 105 constituting the optical element 104 changes according to the voltage.

  In such a microelectromechanical device (optical MEMS) 101, light is irradiated onto the surface of the reflective film 152 constituting the modulation unit 105, and the driving position of the modulation unit 105 of the beam-shaped optical element 104, that is, from the lower electrode 103. Since the reflection direction of the light incident on the modulation unit 104 changes according to the height, it can be configured as a so-called optical switch by detecting only the light reflected in a specific direction.

  Further, when the micro electro mechanical device 101 is configured such that a large number of optical elements 102 are arranged in parallel as shown in FIG. 9B, the height of the large number of optical elements 104 with respect to the lower electrode 103 of the modulation unit 105 is increased. By alternately making a difference, it is possible to switch from a state in which 0th-order reflected diffracted light is generated to incident light to a state in which 1st-order or higher-order reflected diffracted light is generated, thereby forming a predetermined light modulation device.

  Incidentally, contrast is one of the characteristics of such an optical microelectromechanical device. Contrast can be expressed by the ratio of the light intensity in the state where the 0th-order reflected diffracted light is generated (OFF state) and the state where the 1st-order or higher-order reflected diffracted light is generated (ON state), thereby improving the contrast characteristics. In order to achieve this, it is required to increase the light intensity in the ON state or decrease the light intensity in the OFF state.

  As a method for improving the light intensity in the ON state, the positions of the optical elements arranged in parallel are brought close to each other, the gap (Gap) width of the mechanical grating is narrowed, and the beam shape of this optical element is inclined with respect to the juxtaposed arrangement direction. It has been proposed to have a blazed structure (see, for example, Patent Document 5). However, these methods have many problems in the device process (manufacturing process), and the contribution to the characteristic of contrast is small. Therefore, in order to improve the luminance characteristics, a method of forming a reflection enhancement film on the surface of the reflection film is taken. (See, for example, Patent Documents 6 and 7).

  On the other hand, in order to reduce the light intensity in the OFF state, it is important to prevent generation of unnecessary light such as scattered light and to prevent this unnecessary light from entering the detector (detector). Scattered light is generated when there are irregularities on the surface of the reflective film that constitutes the modulation part of the optical element, or when light that has leaked to the periphery is irregularly reflected from a reflection film other than the modulation part. When the light enters the detector, a slight amount of light is detected in spite of the OFF state where light does not enter.

In such a light modulation device such as the above-mentioned micromirror (DMD) or LCOS (Liquid Crystal On Silicon), almost all of the device outermost surface where incident light can reach is covered with a reflector. However, since the members other than the modulation unit (for example, the support unit that also serves as the drive unit) are hidden under the reflector, this is not necessarily a problem.
However, in the case of a microelectromechanical device (optical MEMS; mechanical grating device) using diffracted light, beam-like optical elements fixed with supporting portions at both ends are arranged in parallel (for example, one-dimensionally). Because of this structure, part of the light reaches the beam end (supporting portion) and its periphery as light enters the beam central region (modulating portion), and scattered light is generated.
Further, in such a microelectromechanical device, since precise light modulation is possible, it is difficult to ignore the influence of the scattered light even if the noise due to the scattered light is small, and further reduction of the scattered light is required. Become.

  9A and 9B, after manufacturing the device to the state shown in FIGS. 9A and 9B, for example, in order to obtain an electronic device such as a display device or a communication device, as shown in FIG. The base 107 common to other devices is passed through a step of sealing the mechanical grating device) with the solder material 108 and the transmission material 109 and a packaging step of providing the light shielding material 110 that defines the optical path of incident light through the opening 110a. Will be fixed on top.

However, in such an electronic device manufacturing process in which a microelectromechanical device is fixed as an optical system, there is always a process margin (manufacturing error) in each process. Therefore, for example, a deviation occurs between the center of the opening 110a and the center of the beam-shaped optical element 104, and it becomes extremely difficult for incident light to enter the center of the modulation unit 105 without error.
In particular, in the sealing step by forming the solder material 108, the light shielding material 110, and the like, the incident light incident position is shifted in the order of microns, and for example, a common covering material with other semiconductor devices 113 formed around There is also a problem that the arrangement position of the light shielding material 110 is shifted and cannot contribute to the suppression of scattered light, and the brightness is lowered and the contrast is deteriorated due to the scattered light.
As one countermeasure against the problem due to the manufacturing error, a method of reducing the generation of scattered light by introducing a dielectric film in a part of the transmission material 109 (installation of the transmission material 109 after the optical element 104 is formed). In the module assembling process, a method of forming a structure capable of suppressing scattered light is conceivable. In this case, the process margin of the light shielding material 110 can be avoided, but the process margin of the solder material 108 cannot be avoided. . Therefore, it is difficult to sufficiently suppress the reduction of scattered light and contrast in the module assembly process after the optical element 104 is manufactured.
U.S. Pat.No. 4,011,009 U.S. Pat.No. 5,115,344 US Patent No. 5,311,360 U.S. Pat.No. 5,459,610 JP 2004-245973 A JP 2004-317653 A JP 2002-341269 A

  The present invention has been made in view of such a problem, and an object of the present invention is to provide a microelectromechanical device having excellent contrast characteristics, an electronic device having the microelectromechanical device, and the microelectromechanical device. It is in providing the manufacturing method of.

  A microelectromechanical device according to the present invention is a microelectromechanical device in which an optical element having a support portion coupled to the substrate and a modulation portion facing the substrate via the support portion is provided on the substrate. The optical element has a reflection film that optically modulates incident light at least in the modulation section, and a part of the reflection film constituting the optical element is covered with an antireflection film. It is characterized by that.

  An electronic device according to the present invention is an electronic device having a microelectromechanical device, and the microelectromechanical device is opposed to the substrate via a support portion connected to the substrate on the substrate and the support portion. A microelectromechanical device provided with an optical element having a modulation unit, the optical element having a reflection film for optically modulating incident light at least in the modulation unit, and the reflection film constituting the optical element A part of is covered with an antireflection film.

  The method for manufacturing a microelectromechanical device according to the present invention includes: a first step of forming a reflective film on a substrate that constitutes a support portion and a modulation portion facing the substrate through the support portion; It has a second step of covering at least a part of the film and forming an antireflection film, and a third step of sealing the reflection film and the antireflection film.

  According to the microelectromechanical device of the present invention, there is provided an optical element having a support unit coupled to the substrate and a modulation unit facing the substrate via the support unit, and the optical element includes at least the modulation unit. Since a reflection film is provided and a part of the reflection film is covered with the antireflection film, the scattered light can be reduced.

  An electronic device according to the present invention has a microelectromechanical device, and in this microelectromechanical device, an optical element having a support unit coupled to a substrate and a modulation unit facing the substrate via the support unit is provided. Since this optical element has a reflection film at least in the modulation part, and a part of this reflection film is covered with the antireflection film, the contrast at the output is reduced by reducing the scattered light in the microelectromechanical device. Reduction of the reduction is achieved.

  The method for manufacturing a microelectromechanical device according to the present invention includes a first step of forming a reflective film that constitutes a support section and a modulation section on a substrate, and an antireflection film is formed covering at least a part of the reflective film. Since the second step and the third step of sealing the reflection film and the antireflection film are included, it is possible to manufacture a microelectromechanical device in which scattered light is reduced.

Embodiments of a microelectromechanical device (optical MEMS; mechanical lattice device), an electronic device having the microelectromechanical device, and a method of manufacturing the microelectromechanical device according to the present invention will be described below.
In the present embodiment, in a microelectromechanical device having an optical element in which a reflector on the surface of the element produces an optical effect, scattered light generated based on light incident on a portion other than an optically acting portion (modulation unit) An example having an optical element formed with a non-light-reflective (light-absorbing) antireflection film that suppresses the above and improves the contrast will be described.

<Embodiment of micro electro mechanical device>
First, an embodiment of a microelectromechanical device according to the present invention will be described.
1A and 1B are a schematic configuration diagram of a microelectromechanical device according to this embodiment and a schematic perspective view of a main part.

The microelectromechanical device 1 according to the present embodiment is provided with a lower electrode 3 on the surface of a substrate 2, and at least electrically separated from the lower electrode 3 and connected to the substrate 2, and the support portion. A so-called beam-shaped optical element 4 having a modulation unit 5 facing the substrate 3 via 6 is provided. Further, the modulation section 5 and the support section 6 constituting the optical element 4 are integrally formed by a common multilayer film including the dielectric films 51 and 61 and the reflection films 52 and 62 serving as the upper electrodes facing the lower electrode 3. The modulation unit 5 is supported at both ends by the support unit 6, is defined at a predetermined height position from the substrate 2 and the lower electrode 3, and the optical element 4 straddles the lower electrode 3.
In this embodiment, a bridge-type beam-shaped optical element 4 that is opposed to the lower electrode 3 and is electrically insulated from the lower electrode 3 by a gap is separated from the optical element 4 and covered on the substrate 2. A substrate 2 sealed with a solder material 8 to be attached and a transmission material 9 supported and fixed by the solder material 8 and further formed with these members is mounted on a base 7 common to other devices and the like. The optical path of incident light is defined and fixed by the light shielding material 10.

The substrate 2 can be configured by, for example, a substrate in which an insulating film is formed on a semiconductor substrate such as silicon (Si) or gallium arsenide (GaAs), or an insulating substrate such as a quartz substrate or a glass substrate.
The lower electrode 3 can be constituted by a polycrystalline silicon film doped with impurities, a metal film (for example, W, Cr vapor deposition film), or the like.
The beam-shaped optical element 4 integrally formed by the modulation unit 5 and the support unit 6 includes an insulating film such as a silicon nitride film (SiN film) and an Al film having a thickness of about 100 nm formed on the upper surface thereof. And a drive-side electrode that also serves as a reflective film.

In this microelectromechanical device 1, as shown in FIG. 1A, the reflective film 52 that forms the upper drive side electrode and constitutes the modulation section 5 has a potential applied to the lower electrode 3 on the substrate 2 side between the electrodes. In response to this, due to electrostatic attraction or electrostatic repulsion, the parallel state at the height defined by the support portion 6 is displaced, for example, into a recessed state (shown by a broken line) at a lower position.
That is, when a predetermined voltage is applied between the beam-shaped optical element 4 and the lower electrode 3, the height of the modulation unit 5 constituting the optical element 4 changes according to the voltage, and the original parallel state is obtained. By selecting the displacement height between the two, predetermined light modulation can be performed according to the state.
For example, diffracted light has different diffraction directions depending on the diffraction order, so by providing an opening for detecting diffracted light (for detector) and taking in light only in a specific direction (for example, only primary reflected diffracted light), It is possible to switch the light height (ON state) and dark state (OFF state) by switching the height of the beam by electrical control, and to constitute an electronic device such as a display device (image display device) described later. Is also possible.

  In the microelectromechanical device 1 according to this embodiment, a part of the reflection films 52 and 62 constituting the optical element 4 is covered with the antireflection film 63. As a material constituting the antireflection film 63, Ti, (titanium) W (tungsten), Cr (chromium), Ni (nickel), Mo (molybdenum), Ta (tantalum), Fe (iron) are used as metal materials. It is preferable to have a structure including at least one or having a dielectric film (silicon film, silicon nitride film, silicon oxynitride film, etc.) containing Si. A single layer or a stacked layer of a plurality of layers can be formed by a structure in which an oxide film and a nitride film are paired. In particular, according to the laminated film of a combination of a metal material and its oxide, mechanical strength such as adhesion can be imparted to the antireflection film that suppresses scattered light.

Specific examples of the laminated film include Ti / SiN and W / SiN. For example, Ti / SiN is used as a material for a MOS wiring or a wiring protective film in a semiconductor process, and Ti can be formed without spattering (altering) the Al film by using sputtering and SiN using plasma CVD. As for processing, lift-off can be used in consideration of the influence on the Al reflective film. By providing SiO ₂ or the like as an etch stop film at an appropriate film thickness at the interface between Al and Ti, dry etching can be used. Processing is also possible. Further, for example, W / SiN is also a material used as a wiring material for MOS in a semiconductor process, and can be easily formed at a low temperature by sputtering or the like in consideration of being formed on Al as well as CVD. .
In other words, the anti-reflection film is configured in consideration of the actual manufacturing process as will be described later, thereby preventing alteration and deformation of other materials constituting the optical element (such as Al constituting the reflection film). Is preferred.

According to the microelectromechanical device 1 according to the present embodiment, the light is incident mainly in a portion other than the main portion of the modulation portion 5 of the microelectromechanical device (optical MEMS) that uses reflection and / or diffraction of light. In a region other than the region, an antireflection film for suppressing light scattering is formed on a part of the outermost layer of the optical element 4 to suppress generation of scattered light due to irregular reflection or the like.
In addition, by providing the antireflection film 63 directly on the surface of the optical element 4 constituting the main part of the micro electromechanical device 1, as will be described in an embodiment of the manufacturing method described later, it is possible to prevent misalignment in the manufacturing process. The generation of unnecessary scattered light can be suppressed.
In particular, as shown in FIG. 1A, not only the support unit 6 but also an adjacent region 5a adjacent to the support unit 6 of the modulation unit 5 (for example, the support unit 6 is defined within a range in which the driving of the optical element 4 is not hindered. It is considered that the generation of unnecessary scattered light can be more reliably suppressed by providing the antireflection film 63 in the vicinity of both ends of the parallel plane.

The antireflection film 63 covering a part of the reflection films 52 and 62 constituting the optical element 4 is not limited to the above-described structure, and various characteristics required for the purpose of the microelectromechanical device 1 and the beam-like optical element 4. It is preferable to appropriately select the material and the arrangement shape according to the priority order.
For example, the antireflection film 63 can take any of the above-described configurations, but when a laminated film configuration is formed by combining a film made of Ti alone or W alone and an oxide film thereof, as described later, it can be easily manufactured. Therefore, it is considered particularly preferable.

Further, for example, as shown in FIG. 2A, if the reflection film is covered with the antireflection film 63 in the support portion 6 and the adjacent region 5 a of the modulation portion 5 with respect to the support portion 6, the electrostatic effect can be obtained. With respect to the modulated light from the modulation unit 5 for driving, it is possible to obtain only modulated light having particularly desired characteristics.
Further, for example, as shown in FIG. 2B, if the reflection film 62 is covered only by the antireflection film 63 in the support section 6, the influence of the antireflection film 63 on the electrostatic drive of the modulation section 5 is described above. It is possible to suppress the generation of scattered light while reducing it more than in the configuration described above.
Further, for example, as shown in FIG. 2C, the antireflection film 63 may be provided only in the vicinity of the support portion 6 in contact with the substrate 3, while at least ensuring electrical insulation with the lower electrode 3. The antireflection film 63 is extended and provided not only on the surface of the optical element 4 but also on the exposed surface of the substrate 3, so that scattered light is generated in the sealed space by the solder material 8 and the transmission material 9. Thus, it is possible to avoid it more reliably.

Next, the result of simulating the reflection spectrum for the generation of reflected light in a microelectromechanical device having an antireflection film on a part of the optical element surface will be described.
First, FIG. 3 shows a simulation result in the case where the antireflection film is formed of a Ti / SiN laminated film on the reflection film (Al; film thickness 100 nm) constituting the modulation portion of the optical element. In this simulation, the generation of reflected light was examined for each of the cases where the thickness of the Ti layer was fixed at 100 nm and the thickness of the SiN layer was 30 nm, 40 nm, and 50 nm.
From the simulation results shown in FIG. 3, it was confirmed that the reflectivity of the entire wavelength band in the visible light region can be suppressed to less than 20% by selecting the thickness of the SiN layer in the case of this antireflection film configuration.

Next, FIG. 4 shows a simulation result in the case where the antireflection film is formed of a laminated film of W / SiN on the reflection film (Al; film thickness: 100 nm) constituting the modulation unit of the optical element. Also in this simulation, the generation of reflected light was examined for each of the cases where the thickness of the W layer was fixed to 100 nm and the thickness of the SiN layer was 30 nm, 40 nm, and 50 nm.
From the simulation results shown in FIG. 3, it was confirmed that the reflectivity of the entire wavelength band in the visible light region can be suppressed to less than 20% by selecting the thickness of the SiN layer in the case of this antireflection film configuration.

Subsequently, FIG. 5 shows a case where only the reflection film (Al; film thickness 100 nm) constituting the modulation portion of the optical element is formed, and SiO ₂ (film thickness 50 nm) and the above-described condition Ti / SiN (100 nm) on the reflection film. / 40 nm) or W / SiN (100 nm / 50 nm) is formed in comparison simulation results.
By providing an antireflection film in a region that becomes a scattering factor (for example, a support part), the reflectance with visible light can be suppressed to a fraction of that of when the reflective film (Al film) is on the outermost surface. I was able to confirm.

<Embodiment of Manufacturing Method of Micro Electromechanical Device>
Next, an embodiment of a method for manufacturing a microelectromechanical device according to the present invention will be described.
FIG. 6A to FIG. 6C and FIG. 7A to FIG. 7C show process drawings for explaining a method for manufacturing a microelectromechanical device according to this embodiment.

First, as shown in FIG. 6A, a substrate 2 made of crystalline Si is prepared, and an insulating film (not shown) between the substrate 2 and another member is held on the substrate 2 at, for example, 950 ° C. in an oxygen atmosphere. As a result, a thermal oxide film is formed.
Subsequently, a thin film that finally becomes the lower electrode 3 is formed of conductive Si or metal (W, Ti, etc.). Specifically, for example, the conductive Si film is formed by forming an intrinsic poly-Si film or intrinsic a-Si by using a silane (SiH ₄ ) or hydrogen (H ₂ ) gas by a low pressure CVD method, and then forming phosphorus (P ) Is introduced by ion implantation or thermal diffusion, or the conductive film is formed directly by adding phosphine (PH ₃ ) during film formation. The metal film is formed by sputtering or CVD.
Subsequently, the thin film is patterned to form a lower electrode (electrode pad) 3, and then a thermal oxide film (not shown) is formed on the surface of the lower electrode 3 in an oxygen atmosphere at 950 ° C., for example. 11 is formed of, for example, a-Si, and a laminated film that finally becomes the optical element 4 by the modulation unit 5 and the support unit 6 so as to straddle the lower electrode 3 through the sacrificial layer 11 is formed as a dielectric film of, for example, SiN And a reflective film made of, for example, Al having a thickness of 100 nm, and then patterning the laminated film into a predetermined shape to obtain the target dielectric films 51 and 61 and the reflective films 52 and 62. Do.

Subsequently, as shown in FIG. 6B, after a resist is applied to the central region of the optical element 4 which finally becomes the main exposed portion of the reflective film 52, the resist 12 and the reflective film 62 are formed as shown in FIG. 6C. A thin film that finally becomes an antireflection film is formed so as to cover the upper surface.
Subsequently, as shown in FIG. 7A, a predetermined antireflection film 63 is formed by patterning by lift-off, and then the sacrificial layer 11 is removed by etching to form the optical element 4 as shown in FIG. 7B. The second step is performed. In this step, the sacrificial layer 11 can be removed using XeF ₂ (xenon difluoride) or the like if dry etching. Incidentally, for example, if it is formed by the beam shape of the optical element 4 itself Si system constitutes a sacrificial layer by SiO _2, it is possible to perform the etching of SiO ₂ by HF.

  Subsequently, as shown in FIG. 7C, a transparent material 9 made of, for example, glass is prepared, and adhesion with, for example, gold (Au) for joining a solder material described later at a position separated from the optical element 4 of the substrate 2 is performed. A layer (not shown) is provided by patterning, and an adhesion layer (not shown) is also provided by patterning on the transmissive material 9 corresponding to the formation position on the substrate 2. As a specific method of patterning, a method of forming a resist first, patterning and then forming an adhesion layer on the entire surface and lifting off may be used, or after forming an adhesion layer, resist patterning is performed, and dry etching or Although a wet etching method may be used, a lift-off method is considered more preferable in order to reduce the attack (burden) on the reflective film.

After the adhesion layer is formed on the substrate 2 and the transmission material 9, solder bonding is performed at the position where the adhesion layer is formed using the solder material 11, and the optical of the micro electro mechanical device finally obtained by the transmission material 9 and the substrate 2. The main part including the element 4 is sealed, and the third step is performed.
In general, since MEMS performs switching due to mechanical fluctuations in addition to electrical signals, it is necessary to keep elements in a certain environment (for example, in a vacuum atmosphere or an inert gas atmosphere). It is preferable to seal.
Subsequently, the substrate 2 is placed on a base 7 that is shared with a semiconductor device such as a peripheral drive IC (not shown) and packaged as a set using a light shielding material 10, so that FIG. The microelectromechanical device shown is obtained.
In the present invention, since the generation of scattered light is suppressed by the antireflection film 63, the positional shapes of the transmission material 9 and the light shielding material 10 are misaligned (for example, the misalignment between the glass and the element by the solder material 8 and the resin, that is, the light shielding). The displacement of the position of the material 110) is allowed to be larger than that in the prior art, and it becomes possible to avoid delays in manufacturing and a decrease in yield based on the process margin.

  That is, according to the method for manufacturing a microelectromechanical device according to the present embodiment, it is generally 50 times the misalignment of mask patterning compared to the case where an antireflection film (dielectric film) is provided on the surface of the transmission material 9. It is possible to suppress solder misalignment that is considered to occur at a scale of ˜100 times, and to avoid a light spot shift due to solder misalignment and a decrease in yield due to this. In addition, according to the method for manufacturing a microelectromechanical device according to the present embodiment, compared with the conventional configuration in which the generation of scattered light is suppressed by defining the optical path of incident light only by the light shielding material 10. This eliminates the need for special processing such as a groove in which the resin stops, so that the packaging process can be performed more easily.

That is, according to the method of manufacturing a microelectromechanical device according to the present embodiment, the optical path of incident light and generation of scattered light are suppressed on the surface of the transmission material (glass) 9 and the surface of the light shielding material (package) 10. Instead, it can be achieved by forming the optical element 4 at a position including the essential part.
Therefore, according to the microelectromechanical device manufacturing method according to the present embodiment, when the MEMS element is sealed or packaged, the scattered light suppression is not impaired even if a positional shift occurs due to process variations. Further, as a result, the arrangement of the transmissive material 9 and the light shielding material 10 is allowed to vary due to misalignment within the design value range of these members themselves. It is also possible to avoid excessive stringency.

Note that Ti or W is particularly preferably used as the metal material constituting the antireflection film and the lower electrode. This is because, among heavy metals that are prone to contamination and defects to semiconductors, these are materials that can also be used for MOS gate electrodes and wiring. In addition, when processing a metal called a so-called heavy metal, it is often required to heat to a temperature at which peripheral members such as a reflective film change in quality, so that, for example, even when Al is used for the reflective films 52 and 62, low-temperature process conditions are used. While it is difficult to work at (atmospheric temperature of 200 ° C. or less), Ti and W are preferable because they can be processed under these low-temperature process conditions.
Further, the processing by lift-off including the processing of the above-described antireflection film is preferably performed under the above-described atmospheric conditions of 200 ° C. or lower, particularly 100 ° C. or lower when possible. This is because it is considered that it is more preferable to select the temperature of the atmosphere in the processing by lift-off as, for example, 100 ° C. or less as the temperature at which the resist does not harden according to the composition of the resist.
Since the antireflection film 63 does not directly contribute to the light modulation, a slight deformation (unevenness) or alteration is allowed. Therefore, the antireflection film 63 is formed with roughness by a so-called texture structure or the like, so that scattered light is scattered. Can be further reduced.

Further, as in the present embodiment, by forming an insulating film such as a thermal oxide film, it is possible to prevent excessive etching (so-called punch-through) and to form a desired shape.
This can be done by using, for example, a conductive thin film, not necessarily depending on the insulating film, and it is preferable to select appropriately according to the etching distance in the width direction and the depth direction in etching, so-called selectivity.

<Embodiment of electronic device>
Next, an embodiment of an electronic device according to the present invention will be described.
In the present embodiment, an example of an electronic device configured as a display device (so-called laser display) by the above-described micro electro mechanical device will be described.
FIG. 8 shows a schematic configuration diagram of an electronic device according to the present embodiment.

As shown in FIG. 8, the electronic device 70 according to the present embodiment has red (R), green (G), and blue (B) laser light sources 71R, 71G, and 71B, and each laser light source. Mirrors 72R, 72G, 72B sequentially provided on the optical axis, each color illumination optical system (lens group) 73R, 73G, 73B, and a micro electromechanical device as the light modulation device shown in FIG. 1A that functions as a light modulation element Devices 1R, 1G, and 1B are provided.
From the laser light sources 71R, 71G, 71B, for example, laser beams of R (wavelength 642 nm, light output about 3 W), G (wavelength 532 nm, light output 2 W) B (wavelength 457 nm, light output 1.5 W) are emitted, respectively. The
Furthermore, the electronic device 70 according to the present embodiment emits red (R) laser light, green (G) laser light, and blue (B) laser light whose light intensity is modulated by the microelectromechanical devices 1R, 1G, and 1B, respectively. A color synthesis filter 74 to be synthesized, a spatial filter 75, a diffuser 76, a mirror 77, a galvano scanner 78, a projection optical system (a lens group 79, and a screen 80. The color synthesis filter 74 is composed of, for example, a dichroic mirror. .

In the electronic device 70 according to the present embodiment, the RGB laser beams emitted from the laser light sources 1R, 1G, and 1B pass through the mirrors 72R, 72G, and 72B, respectively, from the color lens groups 73R, 73G, and 73B. The signals are input to the devices 1R, 1G, and 1B synchronously.
Further, each laser beam is spatially modulated by being diffracted by these microelectromechanical devices 1R, 1G, and 1B, and the diffracted light of these three colors is synthesized by the color synthesis filter 74, and then the signal is outputted by the spatial filter 75. Only the components are removed.
Subsequently, this RGB image signal is reduced in laser speckle by the diffuser 76, passes through a mirror 77, is developed in space by a galvano scanner 78 synchronized with the image signal, and is projected onto a screen 80 by a projection optical system 79. As projected.
According to the electronic device 70 according to the present embodiment, the RGB light finally obtained is obtained by the microelectromechanical devices 1R, 1G, and 1B, so that the scattered light generated when each light is turned off is reduced, and the contrast ratio is reduced. Can be improved.

  As described above, the embodiments of the microelectromechanical device, the electronic device, and the microelectromechanical device according to the present invention have been described. However, the numerical conditions such as the materials used, the amount thereof, the processing time, and the dimensions mentioned in the above description are It is only a preferred example, and the dimensional shape and the arrangement relationship in each drawing used for the description are also schematic. That is, the present invention is not limited to this embodiment.

For example, as a configuration of the antireflection film, in addition to the above-described example, in order to lower the reflectance, for example, Cr, Ni, Mo, Ta, Fe, or alloys thereof, and oxide films of these materials Can be constituted by a single layer or a plurality of laminated films.
Moreover, the microelectromechanical device according to the present invention can be configured as a mechanical lattice device having, for example, a blazed optical element.
In addition, the electronic device having the microelectromechanical device according to the present invention is not limited to the one constituting the display device, and constitutes, for example, a drawing device used for pattern formation by exposure and an optical communication device contributing to communication by switching. The present invention can be variously modified and modified.

1A and 1B are a schematic configuration diagram showing an exemplary configuration of a microelectromechanical device that constitutes an electronic device according to the present invention, and a schematic perspective view of a main part thereof. AC is a schematic block diagram which shows the structure of the other example of the microelectromechanical device which comprises the electronic device which concerns on this invention, respectively. It is a schematic diagram which shows the relationship between the structure of the multilayer film which comprises a modulation | alteration part, and the simulation result of the reflectance of light with respect to this structure in an example of the microelectromechanical device which concerns on this invention. It is a schematic diagram which shows the relationship between the structure of the multilayer film which comprises a modulation | alteration part, and the simulation result of the reflectance of light with respect to this structure in an example of the microelectromechanical device which concerns on this invention. It is a schematic diagram which shows the relationship between the structure of the multilayer film which comprises a modulation | alteration part, and the simulation result of the reflectance of light with respect to this structure in an example of the microelectromechanical device which concerns on this invention. FIGS. 4A to 4C are process diagrams for explaining an example of a method for manufacturing a microelectromechanical device according to the present invention. FIGS. 4A to 4C are process diagrams for explaining an example of a method for manufacturing a microelectromechanical device according to the present invention. It is a schematic block diagram which shows the structure of an example of the electronic device which concerns on this invention. AC is a schematic cross-sectional view of a main part, a schematic perspective view of a main part, and a schematic configuration diagram of a conventional microelectromechanical device, respectively.

Explanation of symbols

  1, 1R, 1G, 1B: micro electromechanical device, 2 ... substrate, 3 ... lower electrode, 4 ... optical element (beam), 5 ... modulation unit, 6 ... support Part 7 ... base, 8 ... solder material, 9 ... transmitting material, 10 ... light shielding material, 11 ... sacrificial layer, 12 ... resist, 51, 61 ... dielectric Films 52, 62 ... reflective film, 63 ... antireflection film, 70 ... electronic device, 71R ... red laser, 71G ... green laser, 71B ... blue laser, 72R, 72G , 72B ... mirror, 73R, 73G, 73B ... lens (group), 74 ... color synthesis filter (dichroic mirror), 75 ... spatial filter, 76 ... diffuser, 77 ... mirror 78 ... Galvano scanner, 79 ... Projection lens (group), 80 Screen 101, microelectromechanical device, 102, substrate, 103, lower electrode, 104, optical element (beam), 105, modulator, 106, support, 107 ... Base, 108 ... Solder material, 109 ... Transmission material, 110 ... Light shielding material, 110a ... Opening, 113 ... Semiconductor devices 151, 161 ... Dielectric film, 152, 162 ... Reflective film

Claims (17)

A microelectromechanical device provided on a substrate with an optical element having a support unit coupled to the substrate and a modulation unit facing the substrate via the support unit,
The optical element has a reflective film that optically modulates incident light at least in the modulation section;
A part of the reflection film constituting the optical element is covered with an antireflection film. 2. The microelectromechanical device according to claim 1, wherein at least a part of the reflection film is covered with the antireflection film only in the support portion. 2. The microelectromechanical device according to claim 1, wherein at least a part of the reflection film is covered with the antireflection film only in an adjacent region of the modulation unit to the support unit and the support unit. . The microelectromechanical device according to claim 1, wherein the modulation is diffraction. The micro electromechanical device according to claim 1, wherein the support portion and the modulation portion are integrally formed. The microelectromechanical device according to claim 1, wherein the support portion and the modulation portion are formed of a common multilayer film. The microelectromechanical device according to claim 1, wherein an exposed surface of the substrate is partially covered with the antireflection film. The antireflection film includes at least one of Ti (titanium), W (tungsten), Cr (chromium), Ni (nickel), Mo (molybdenum), Ta (tantalum), and Fe (iron). The microelectromechanical device according to claim 1, wherein The microelectromechanical device according to claim 1, wherein the antireflection film is formed of a dielectric film containing Si. The optical element is formed at least electrically separated from a lower electrode provided on the substrate surface,
The microelectromechanical device according to claim 1, wherein the reflective film serves as an upper electrode facing the lower electrode. An electronic device having a microelectromechanical device,
The microelectromechanical device is
A microelectromechanical device provided on a substrate with an optical element having a support unit coupled to the substrate and a modulation unit facing the substrate via the support unit,
The optical element has a reflective film that optically modulates incident light at least in the modulation section;
An electronic device having a configuration in which a part of the reflection film constituting the optical element is covered with an antireflection film. A first step of forming, on the substrate, a reflection film that constitutes a support portion and a modulation portion facing the substrate via the support portion;
A second step of covering at least part of the reflective film and forming an antireflection film;
And a third step of sealing the reflection film and the antireflection film. A method of manufacturing a microelectromechanical device. Prior to the third step, the antireflection film is processed at 200 ° C. or lower. The method of manufacturing a microelectromechanical device according to claim 12. Prior to the third step, the antireflection film is processed at 100 ° C. or lower. The method of manufacturing a microelectromechanical device according to claim 12. Prior to the third step, lift-off is performed as processing of the antireflection film. The method of manufacturing a microelectromechanical device according to claim 12. Prior to the first step, a lower electrode facing the modulator is formed on the surface of the substrate. The method of manufacturing a micro electro mechanical device according to claim 12. The method of manufacturing a microelectromechanical device according to claim 12, wherein the antireflection film includes at least one of Ti (titanium) and W (tungsten).

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