JP4835024B2 - Light control element, manufacturing method thereof, and display device - Google Patents

Description

  The present invention relates to a light control element that includes a micro electro mechanical systems (MEMS) structure and performs scanning of an optical signal for image display, for example, and a manufacturing method thereof. The present invention also relates to a display device using this light control element.

Conventionally, a method of scanning light with a two-dimensional mirror and displaying an image has been proposed (see, for example, Patent Document 1 and Patent Document 2). In a display system using such a method, a size of about 1 mm square is required in relation to NA (Numerical Aperture) in order to narrow light to a mirror (movable member) that is a key part. In addition, in order to scan and display NTSC (National Television Systems Committee) and high-definition images by scanning a single light, it is necessary to have a large amplitude, that is, a rotation angle, and a high scanning frequency of 15 kHz or 30 kHz. Is required.
Japanese translation of PCT publication No. 2003-513332 (FIG. 17) JP 2000-235152 A

  In order to drive the mirror at such a high speed, it is basically necessary to reduce the rotational moment of inertia and increase the torsion spring constant to raise the resonance point. On the other hand, in order to keep a mirror having a large area of about 1 mm square during flat driving at high speed, it is desirable to have a highly rigid structure, that is, to increase the thickness. However, increasing the thickness of the mirror increases the moment of inertia and makes high-speed driving difficult. Further, if the torsion spring constant is increased, the direction becomes difficult to rotate, which may be disadvantageous for increasing the rotation angle. Thus, it is extremely difficult to realize a mirror having a large area, a large rotation angle, and a high-speed drive, and there is room for further improvement in the structure and the manufacturing method.

  The present invention has been made in view of such problems, and an object of the present invention is to provide a light control element that includes a highly rigid movable member and can be driven at high speed, a method for manufacturing the same, and a display device using the light control element. It is to provide.

Method for manufacturing an optical control element according to the present invention comprises a plate-like movable member having a reflecting surface to the surface, respectively the movable member and the outer frame member, at a position facing each of the movable member supporting a variable rotary members rotatably And a frame member, and a pair of support portions that serve as a pivot center of the movable member . The light control element manufacturing method comprises a semiconductor substrate with an oxide layer on a holding substrate. A step of selectively removing other regions of the semiconductor film while leaving a region where the movable member , the support portion, and the outer frame member are to be formed, and a portion of the region where the movable member is to be formed on the semiconductor film. By selectively forming a semiconductor growth layer, a step of forming a crosspiece structure having a crosspiece width of 3 μm or more on the back surface of the movable member, and at least a movable member formation region of the holding substrate and the oxide layer are selectively removed. The movable member and It is obtained as a step of forming a frame member.

In the method of manufacturing by that the light control device of the present invention, first, a substrate having a semiconductor film and between the oxide layer on the holding substrate, at least another part, leaving the movable member forming region of the semiconductor film Are selectively removed. Next, a semiconductor growth layer is selectively formed in a part of the movable member formation scheduled region on the semiconductor film. Thereby, the crosspiece structure is integrally formed on the back surface of the movable member formation scheduled area. Subsequently, the movable member and the outer frame member are formed by selectively removing at least the movable member formation scheduled region of the holding substrate and the oxide layer.

According to the manufacturing how the light control device of the present invention, since to form the crosspiece structure on the back surface of the movable member, it is possible to increase the resonance frequency by decreasing the moment of inertia by reducing the moving member The light control element in which the movable member is reinforced by the crosspiece structure can be manufactured. Therefore, a light control element having high rigidity and capable of being driven at high speed can be manufactured.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Prior to the description of the embodiment, a light control element according to a reference example will be described.

[ Reference example ]
FIG. 1 shows the overall configuration of the light control element, and FIG. 2 shows its cross-sectional configuration. The light control element is used to reflect and scan an optical signal in, for example, an image display device or a scanner. For example, the movable member 10 formed of a rectangular flat plate has two opposite sides (here, long sides). ) Are connected to the outer frame portion 30 via the support portions 20, respectively. Fixed side electrodes 40A, 40B, 40C, and 40D are connected to the outer frame portion 30, and rotation side electrodes 50A, 50B, 50C, and 50D are connected to the movable member 10 at positions corresponding to the fixed side electrodes 40A to 40D. Is provided.

  The light control element includes a driving power source 60 for applying a voltage for electrostatic driving between the rotation side electrodes 50A to 50D and the fixed side electrodes 40A to 40D, and driving of the driving power source 60. A control unit 70 that performs control, an activation electrode 80 for applying an initial driving force (activation force) to the movable member 10, and an activation power source connected between the activation electrode 80 and the movable member 10 90.

  The movable member 10 is specifically a reflection mirror, and changes the light reflection direction by, for example, rotationally displacing about an axis (support portion 20) according to a video signal. Here, “rotation” refers to a case where a rotation from a neutral position in one direction reaches a predetermined angle, then rotates in the opposite direction, returns to the neutral position, and further rotates until reaching a predetermined angle. This includes a case in which the rotation is reversed by a predetermined angle in one direction and then the rotation is reversed and the return to the neutral position is stopped. The position where rotation starts is not necessarily limited to the neutral position. As a method of using the reflected signal, for example, the reflected signal when the movable member 10 is tilted at a certain angle from the neutral state in one direction is effective (that is, the ON state), and the reflected signal when the movable member 10 is tilted at a certain angle in the opposite direction. It may be invalidated (that is, off state), or raster scanning may be performed with the reflected signal always valid.

The movable member 10 processes, for example, a so-called SOI (Silicon on Insulator) substrate in which an oxide layer made of silicon dioxide (SiO ₂ ) or the like and a semiconductor film made of silicon or the like are sequentially laminated on the surface of a holding substrate made of silicon. A semiconductor film is formed after the holding substrate and the oxide layer are selectively removed from the SOI substrate, and the flat surface of the semiconductor film is used as a reflection mirror. When the SOI substrate is used in this way, a semiconductor film having zero internal stress can be obtained, so that the movable member 10 is not distorted due to residual stress, and the flatness of the reflecting mirror can be improved.

  The movable member 10 has a plate shape with a thickness of 0.4 μm, for example. The long side length D1 of the movable member 10 is preferably 1000 μm or more (half length is 500 μm or more), and the short side length D2 is preferably 800 μm or more. For example, when it is desired to reduce the diameter of the laser beam to about 300 μm at a distance of about 300 mm from the light emission position, the light emission position needs to have a size of 1.22 mm or more because of the diffraction limit, and the movable member 10 is also equivalent. This is because the size of is required. In order to further reduce the diameter of the laser beam, it is necessary to make the movable member 10 larger. Furthermore, considering the alignment accuracy and the range in which light can be incident when the movable member 10 is rotated and tilted, the movable member 10 needs the dimensions described above.

  FIG. 3 illustrates a configuration in which the movable member 10 and the support unit 20 illustrated in FIG. 1 are viewed from the back side of the movable member 10. A crosspiece structure 11 is provided on the back surface of the movable member 10. As a result, in this light control element, the movable member 10 itself can be made thin to reduce the moment of inertia, so that the resonance frequency can be increased, and the crosspiece structure 11 can reinforce the movable member 10 and increase the rigidity. It has become.

  The crosspiece structure 11 includes, for example, five vertical crosspieces 11A parallel to the long side of the movable member 10 and seven horizontal crosspieces 11B parallel to the short side arranged in a lattice pattern around and inside the movable member 10. It is set. The crosspiece structure 11 is preferably made of, for example, the same material as that of the movable member 10, that is, silicon. This is because the internal stress of the crosspiece structure 11 can be made zero, and the flatness of the movable member 10 can be improved. The crosspiece structure 11 may be made of a material different from that of the movable member 10.

  The width of the crosspiece structure 11 is preferably 3 μm or more, for example. This is because it can be stably manufactured in the manufacturing process. Further, the thickness of the crosspiece structure 11 is preferably larger than that of the movable member 10, for example, 9 times or more that of the movable member 10. This is because even when the movable member 10 and the crosspiece structure 11 are made of the same material, the rigidity of the movable member 10 can be reliably maintained. When the crosspiece structure 11 is made of a material having a higher strength than the movable member 10, the crosspiece structure 11 can be made the same thickness as the movable member 10 or thinner than the movable member 10.

  The number and interval of the vertical bars 11A and the horizontal bars 11B are not particularly limited, and can be set according to the required dimensions of the movable member 10 and the resonance frequency, as will be described in the calculation results described later.

  A reflective film 100 made of a metal material such as aluminum (Al) or gold (Au) is provided on the reflective surface of the movable member 10 in order to increase the reflectance. The thickness of the reflective film 100 is preferably, for example, 1/10 or less of the movable member. This is because warpage of the movable member 10 due to residual stress of the reflective film 100 can be suppressed, and the flatness of the movable member 10 can be improved.

  The support portion 20 is a torsion beam that serves as an axis of rotation of the movable member 10, and supports the movable member 10 so that the movable member 10 can be rotated by a certain angle from side to side. Similar to the movable member 10, the support portion 20 is configured by a semiconductor film in which the holding substrate and the oxide layer are selectively removed from the same SOI substrate. If the support portion 20 is constituted by the semiconductor film of the SOI substrate in this way, since the semiconductor film has no lattice defects at the molecular level, cracks and the like do not grow even if twisted, and therefore the support portion 20 is broken. Difficult and high strength can be obtained.

  The outer frame portion 30 is also formed from the same SOI substrate together with the movable member 10, and has a structure in which another film is formed on the SOI substrate as necessary. The outer frame portion 30 does not necessarily need to be provided so as to surround the movable member 10, and may be provided at least at a fixed position of the support portion 20.

  The fixed side electrodes 40A to 40D are formed to be connected to the outer frame portion 30 and have a plurality of comb teeth 41A, 41B, 41C, and 41D, respectively. These comb teeth 41 </ b> A to 41 </ b> D are arranged so as to be perpendicular to the longitudinal direction of the support portion 20. The fixed side electrodes 40 </ b> A to 40 </ b> D are formed on the flat surface of the semiconductor film after selectively removing the holding substrate and the oxide layer from the same SOI substrate as the movable member 10. Note that a p-type impurity is added to a portion of the semiconductor film constituting the fixed-side electrodes 40A to 40D.

  On the other hand, the rotation side electrodes 50A to 50D are formed on both sides of each of the two support portions 20 so as to be connected to the movable member 10 side, and each of the plurality of comb teeth 51A, 51B, 51C and 51D. These comb teeth 51A to 51D mesh with the comb teeth 41A to 41D on the fixed side electrodes 40A to 40D side. The comb teeth 51 </ b> A to 51 </ b> D are also arranged so as to be perpendicular to the longitudinal direction of the support portion 20. Similarly to the movable member 10, the rotation-side electrodes 50A to 50D are also formed on the flat surface of the semiconductor film after the holding substrate and the oxide layer are removed from the same SOI substrate. Note that a p-type impurity is added to a portion of the semiconductor film that constitutes the rotation-side electrodes 50A to 50D.

  Moreover, as shown in FIG. 4, these rotation side electrodes 50A to 50D are in the same plane as the fixed side electrodes 40A to 40D at the neutral position, and no step is generated between them. Thereby, in this light control element, the voltage for electrostatic drive can be simultaneously applied between the rotation side electrodes 50A to 50D and the fixed side electrodes 40A to 40D on both sides of the support portion 20.

  The rotation-side electrodes 50A to 50D are all electrically short-circuited to each other, and the fixed-side electrodes 40A to 40D are all also electrically short-circuited to each other. The drive power supply 60 is connected to the rotation-side electrodes 50A to 50D. A uniform potential difference can be applied throughout the fixed electrodes 40A to 40D. In addition, in order to electrically isolate | separate rotation side electrode 50A-50D and fixed side electrode 40A-40D, the outer frame part 30 is an oxide layer of an SOI substrate so that the part to which the support part 20 was fixed may be enclosed. A groove 31 reaching up to is provided.

  The driving power source 60 generates an AC potential difference for high-speed driving of the movable member 10, and the waveform may be rectangular or pulsed. The frequency of the driving power source 60 is preferably set to the resonance frequency of the movable member 10 or a frequency that is a multiple or a fraction of the resonance frequency (1/2 or the like). This is because the tilt angle can be further increased by effectively utilizing the resonance characteristics of the movable member 10. The resonance frequency (resonance point) of the movable member 10 is mechanically determined by the movable member 10 and the support portion 20. A specific example of the driving means of the present invention is configured including the driving power source 60 and the control unit 70 described below.

The control unit 70 performs on / off control of the driving power source 60. Here , when the movable member 10 is in a neutral state, the driving power source 60 is turned off, and a starting means (starting power source 90, etc.) described later is used. ), When the movable member 10 is rotated about the support portion 20 and tilted at a certain angle, a gap is generated in a vertical direction between the rotation side electrodes 50A to 50D and the fixed side electrodes 40A to 40D. The power supply 60 is turned on, and an alternating potential difference is generated between both electrodes. Thereby, the rotation torque T is generated in the direction in which the rotation side electrodes 50A to 50D and the fixed side electrodes 40A to 40D are attracted, and the movable member 10 can be driven to rotate.

  The control unit 70 also detects the rotation angle of the movable member 10 based on the electrostatic capacitance between the rotation side electrodes 50A to 50D and the fixed side electrodes 40A to 40D, and is thereby thrown into the movable member 10. The timing with the optical signal can be taken. Therefore, the resistor R is inserted in a part of the circuit including the driving power supply 60. By observing the voltage drop at the resistor R, the current i passing through the circuit is known. The voltage V applied between the rotation side electrodes 50A to 50D and the fixed side electrodes 40A to 40D can be measured with a voltmeter. That is, the rotation side electrodes 50A to 50D and the fixed side electrodes 40A to 40D constitute a variable capacitor, and an equivalent circuit thereof can be expressed as shown in FIG.

  Here, the impedance Z in the variable capacitor between the rotation-side electrodes 50A to 50D and the fixed-side electrodes 40A to 40D is expressed by Equation 1 and Equation 2. Accordingly, the capacitance C is given by the following equation (3). In this way, the capacitance C can be detected in real time. Since the capacitance C changes depending on the rotation angle of the movable member 10, the rotation angle of the movable member 10 can be detected based on the capacitance C.

（ωは加えた電圧の角周波数を表す。）

(Ω represents the angular frequency of the applied voltage.)

  The control unit 70 also adjusts the timing for turning on the driving power supply 60 based on the change state of the rotation angle detected in this way. Here, the movable member 10 is rotated at a certain angle from the neutral state. It is preferable to turn on the drive power supply 60 in a state where the rotation angle becomes small after moving and tilting (that is, in a stage of returning to the neutral state). This is because the electrostatic force generated between the rotation-side electrodes 50A to 50D and the fixed-side electrodes 40A to 40D by the driving power source 60 is only attractive force. Therefore, the most preferable timing is when the rotation angle of the movable member 10 starts to return to the neutral state after reaching the maximum value.

The initial driving of the movable member 10 is performed by a startup power supply 90 (DC power supply) under the control of the control unit 70. In other words, the starting electrode 80 has a step (gap) between the starting electrode 80 and the electrostatic force when the starting power supply 90 is turned on and a potential difference is applied between the starting electrode 80 and the moving member 10. Occurs, the driving torque T is applied to the neutral movable member 10 to forcibly start it. The activation electrode 80 is provided on the outer frame portion 30 with an insulating film 81 made of, for example, silicon nitride (SiN _x , eg, Si ₃ N ₄ ) interposed therebetween. The activation electrode 80 is provided along the short side of the movable member 10 on the side where the support portion 20 is not attached, and has a thickness of about 10 μm, for example, and is made of aluminum, gold, or polysilicon. The activation electrodes 80 are arranged on both sides of the movable member 10 and are provided with activation power sources 90 corresponding to the respective electrodes, but the two activation electrodes 80 are electrically separated. The activation electrode 80 and the activation power supply 90 may be provided only on one side of the movable member 10. A specific example of the activation means of the present invention is configured including the activation power supply 90 and the control unit 70.

  This light control element can be manufactured as follows, for example.

  FIG. 6 shows the flow of the manufacturing method of the light control element, and FIGS. 7 to 12 show the steps in order. 7 to 12 show cross sections taken along line II-II in FIG.

  First, an SOI substrate 110 is prepared as shown in FIG. The SOI substrate 110 has a structure in which an oxide layer 112 made of silicon dioxide having a thickness of, for example, 1 μm and a semiconductor film 113 made of silicon having a thickness of, for example, 20 μm are sequentially stacked on the surface of a holding substrate 111 made of silicon. is there. Here, the volume resistance value of the semiconductor film 113 is preferably as low as possible. For example, antimony (Sb) is preferably added.

  Next, as shown in FIG. 7B, insulating films 81 made of silicon nitride are formed on both surfaces of the SOI substrate 110, and the insulating film 81 on the semiconductor film 113 side is formed into a cross structure by, for example, photolithography. 11, the support part 20, the outer frame part 30, the fixed-side electrodes 40A to 40D, and the rotation-side electrodes 50A to 50D are selectively formed except for the area to be formed (hereinafter referred to as "the area for forming the crosspiece structure 11 or the like"). On the other hand, at least the movable member formation scheduled area 10A of the insulating film 81 on the holding substrate 111 side is selectively removed (step S101). Here, for example, the insulating film 81 on the holding substrate 111 side is selectively removed leaving a region where the outer frame portion 30 is to be formed.

  Subsequently, as illustrated in FIG. 7C, an aluminum film 120 for forming the activation electrode 80 is formed over the semiconductor film 113 and the insulating film 81. After that, as shown in FIG. 8A, the aluminum film 120 is patterned by the photolithography technique, for example, to form the activation electrode 80 (step S102).

  After forming the starting electrode 80, as shown in FIG. 8B, the movable member 10, the support portion 20, the outer frame portion 30, and the fixed side electrodes 40A to 40D are formed on the insulating film 81 on the semiconductor film 113 side. In addition, a photoresist film 130 is formed in a region where the rotation-side electrodes 50A to 50D are to be formed (hereinafter referred to as “a region where the movable member 10 or the like is to be formed”).

  After forming the photoresist film 130, as shown in FIG. 9A, the semiconductor film 113 is formed on the movable member 10 or the like by, for example, deep RIE (Reactive Ion Etching) using the photoresist film 130 as a mask. The area to be formed is left and is selectively removed partway along the thickness direction (step S103). At this time, the thickness of the semiconductor film 113 to be removed is set to about 1 μm, for example.

  After removing the semiconductor film 113 halfway in the thickness direction, the photoresist film 130 is removed as shown in FIG. 9B. Next, as shown in FIG. 10A, using the insulating film 81 on the semiconductor film 113 side as a mask, the region of the semiconductor film 113 that has been removed to the middle in the thickness direction, for example, by the deep RIE method is used as the last in the thickness direction. And the crosspiece structure 11 is formed by selectively removing a part of the movable member formation scheduled area 10A to the middle in the thickness direction (step S104).

  Here, it is preferable to detect the thickness by measuring the reflectance of the semiconductor film 113. Since the spectral reflectance of the semiconductor film 113 made of silicon varies depending on the thickness as shown in FIG. 13, for example, the thickness of the semiconductor film 113 is detected by examining the spectral reflectance of the semiconductor film 113 using micro-spectroscopic light, and etching is stopped. Can be controlled. Etching may be performed by time control.

  After the crosspiece structure 11 is formed, as shown in FIG. 10B, the surface of the SOI substrate 110 is covered with a protective film 140 made of a photoresist. Subsequently, as shown in FIG. 11A, the SOI substrate 110 is cut by, for example, dicing, and a plurality of movable member formation scheduled regions 10A provided on the SOI substrate 110 are individually cut (step S105).

  After individually separating the plurality of movable member formation scheduled regions 10A, as shown in FIG. 11B, the insulating film 81 on the holding substrate 111 side is used as a mask, and TMAH (tetramethylammonium hydroxide) is used as an etching solution. At least the movable member formation scheduled area 10A of the holding substrate 111 is selectively removed by the used anisotropic etching (step S106). Here, for example, the holding substrate 111 is selectively removed leaving a region where the outer frame portion 30 is to be formed.

After removing the holding substrate 111, the protective film 140 made of a photoresist is removed as shown in FIG. Subsequently, as shown in FIG. 12B, at least the movable member formation scheduled region 10A in the oxide layer 112 is formed by wet etching using BHF (Buffered Hydrogen Fluoride) as an etching solution. By selectively removing, the movable member 10, the support part 20, the outer frame part 30, the fixed side electrodes 40A to 40D and the rotation side electrodes 50A to 50D are formed (step S107). Here, for example, the oxide layer 112 is selectively removed leaving a region where the outer frame portion 30 is to be formed. At that time, the insulating film 81 is removed leaving only a portion sandwiched between the activation electrode 80 and the outer frame portion 30. After completion of the etching, hydrofluoric acid is removed by washing, and critical drying is performed by pressurization in a carbon dioxide (CO ₂ ) atmosphere, for example.

  After removing the oxide layer 112 and the insulating film 81, as shown in FIG. 12C, the reflective film 100 is formed on the movable member 10 (step S108). At that time, in order to prevent an electrical short circuit between the rotation side electrodes 50A to 50D and the fixed side electrodes 40A to 40D, the reflective film 100 is formed only on the movable member 10 using a metal mask or the like. It is preferable to do so. Further, at the same time when the reflective film 100 is formed, an electrode pad (not shown) or the like may be formed as necessary. Thus, the light control element shown in FIGS. 1 to 4 is completed.

  Next, an example of the operation of this light control element will be described.

  In this light control element, the light reflection direction changes with the rotation of the movable member 10, and light is scanned. Here, since the crosspiece structure 11 is provided on the back surface of the movable member 10, the movable member 10 can be thinned to reduce the moment of inertia, and the resonance frequency can be increased. Moreover, the movable member 10 is reinforced by the crosspiece structure 11, and the flatness at the time of rotation becomes high. Therefore, light is controlled at high speed and with high accuracy.

  Hereinafter, the improvement of the resonance frequency of the movable member 10 by the crosspiece structure 11 will be described with reference to the calculation result.

  Table 1 shows the result of calculating the resonance frequency of the conventional movable member 410 having no crosspiece structure as shown in FIG. 35 by changing the dimensions of the movable member 410 and the support portion 420 as in Comparative Examples 1-12. It represents. The numerical values and formulas shown in Table 2 were used for the calculation.

  As can be seen from Table 1, for example, in Comparative Example 12 in which the thickness of the movable member 410 is 20 μm, the size is 1 mm × 1.4 mm, the width of the support portion 420 is 24 μm, the thickness is 20 μm, and the length is 200 μm, The frequency is only about 7 kHz and cannot be said to be high speed. In order to obtain a resonance frequency of 30 kHz, for example, as in Comparative Example 10, the thickness of the movable member 410 needs to be reduced to about 2 μm. This is because if the movable member 410 is thick, the moment of inertia increases and the resonance point does not increase. However, if the thickness of the entire surface is 2 μm, the rigidity of the movable member 410 is low, and it may be difficult to maintain flatness during rotational driving.

  Tables 3 to 6 show the results of calculating the resonance frequency of the movable member 10 shown in FIG. 3 by changing the configuration of the crosspiece structure 11 and the dimensions of the movable member 10 and the support portion 20 as in Calculation Examples 1 to 32. It represents. The numerical values and formulas shown in Table 7 were used for the calculation. In Tables 3 to 6, the intervals c2, d2, c3, d3 of the horizontal bars 11B are blank, which means that the corresponding horizontal bars 11B are not provided.

  Further, as Comparative Example 13 with respect to Calculation Examples 1 to 9, the resonance frequency was calculated in the same manner as Calculation Examples 1 to 9 except that no crosspiece structure was provided. Similarly, the resonance frequency was calculated for Comparative Example 14 for Calculation Examples 10 to 14, Comparative Example 15 for Calculation Examples 15 to 26, and Comparative Example 16 for Calculation Examples 27 to 32. The obtained results are shown in Tables 3 to 6 respectively.

  As can be seen from Tables 3 to 6, the resonance frequencies obtained in the calculation examples 1 to 32 are extremely higher than those of the corresponding comparison examples 13 to 16. For example, in the calculation example 32, a good result of about 31.4 kHz is obtained. was gotten. This is because the resonance frequency is increased because the moment of inertia is about 1/20 that of the conventional structure. Further, even if the movable member 10 is thin, it is reinforced by the crosspiece structure 11, so that the rigidity of the movable member 10 is not significantly reduced.

  That is, it can be seen that by providing the crosspiece structure 11 on the back surface of the movable member 10, the moment of inertia can be reduced and the resonance frequency can be increased, and the movable member 10 can be reinforced and maintained rigid by the crosspiece structure 11. .

  Next, drive control of the movable member 10 will be described.

  In the stationary state, the movable member 10 is in a horizontal state as shown in FIGS. Therefore, the rotation side electrodes 50A to 50D are in the neutral position, and are in the same plane with no step with the fixed side electrodes 40A to 40D. In this state, even if a direct-current potential difference is applied between the rotating side electrodes 50A to 50D and the fixed side electrodes 40A to 40D, no rotating torque is generated due to electrostatic force, and the movable member 10 remains stationary. is there.

  14 to 19 are for explaining the operation of the light control element. Here, in order to make the control state by the control unit 70 easy to understand, a driving power source 60 is connected to each of the rotation side electrodes 50A to 50D and each of the fixed side electrodes 40A to 40D. The activation power source 90 is represented as a DC power source and an on / off switch connected between each of the activation electrodes 80 and the movable member 10.

  First, as shown in FIG. 14 and FIG. 15, the control unit 70 generates a potential difference between the activation electrode 80 on one side and the movable member 10 by turning on one activation power supply 90. The movable member 10 is slightly rotated by the electrostatic force. If the movable member 10 is tilted, the potential difference between the activation electrode 80 and the movable member 10 is eliminated by turning off the activation power supply 90. As a result, the movable member 10 is released from the inclined position, and starts subtle self-excited vibration at its inherent resonance frequency. In this way, the movable member 10 is forcibly activated.

  Next, the control unit 70 turns on the driving power supply 60 in accordance with the self-excited vibration of the movable member 10, so that the rotation-side electrode is driven at the resonance frequency of the movable member 10 or a drive frequency that is a multiple or a fraction thereof. A predetermined potential difference is applied between 50A to 50D and fixed side electrodes 40A to 40D. As a result, a rotational torque due to electrostatic force is generated, the self-excited vibration of the movable member 10 is increased, and the rotational angle is increased.

  At that time, as described with reference to FIGS. 1 and 5, the control unit 70 sets the movable member 10 based on the capacitance between the rotation-side electrodes 50 </ b> A to 50 </ b> D and the fixed-side electrodes 40 </ b> A to 40 </ b> D. Detects the rotation angle.

  Then, based on the detected change state of the rotation angle, the control unit 70 selects on / off switching of the driving power supply 60. That is, as shown in FIGS. 16 and 17, the driving power source 60 is turned on and the electrostatic force S is generated at a timing when the rotation angle becomes small as the movable member 10 tries to return to the neutral state. On the other hand, as shown in FIGS. 18 and 19, the driving power source 60 is turned off when the movable member 10 passes the neutral position and the rotation angle increases. Thereby, the rotation angle of the movable member 10 can be effectively increased. Therefore, it is most desirable to turn on the drive power supply 60 at the timing when the movable member 10 starts to return to the neutral state after the rotation angle reaches the maximum value.

  In addition, based on the detection angle of this movable member 10, the input timing of the optical signal made to enter into the movable member 10 from a light source (not shown) can also be adjusted.

Thus, in this light control element, since the crosspiece structure 11 is provided on the back surface of the movable member 10, the resonance frequency can be increased by thinning the movable member 10 to reduce the moment of inertia, and the crosspiece structure. 11, the movable member 10 can be reinforced. Therefore, it is possible to realize a light control element that has high rigidity and can be driven at high speed.

  Moreover, since the rotation-side electrodes 50A to 50D at the neutral position are on the same plane with no step with the fixed-side electrodes 40A to 40D, on both sides of the support portion 20 serving as the rotation axis of the movable member 10, simultaneously A voltage can be applied between the rotation side electrodes 50A to 50D and the fixed side electrodes 40A to 40D. Therefore, the force that the rotation-side electrodes 50A to 50D and the fixed-side electrodes 40A to 40D attract in the horizontal direction is canceled to eliminate unnecessary horizontal movement, thereby enabling efficient and even movement. Further, a large rotational torque can be obtained, and the amplitude of the movable member 10 can be increased.

  Furthermore, since there is no step between the rotation side electrodes 50A to 50D and the fixed side electrodes 40A to 40D at the neutral position, the larger the rotation angle of the movable member 10, the wider the gap between them. Therefore, it is not necessary to consider the step at the neutral position between the rotation-side electrodes 50A to 50D and the fixed-side electrodes 40A to 40D as in the prior art, and the rotation of the movable member 10 is determined by examining the capacitance between the two. The moving angle can be easily detected.

  In addition, the rotation-side electrodes 50A to 50D and the fixed-side electrodes 40A to 40D can be manufactured in the same process, and the manufacturing process is greatly simplified as compared with the conventional vertical comb type. can do.

In this light control element manufacturing method, the crosspiece structure 11 is formed by selectively removing a part of the formation region 10A of the movable member 10 of the semiconductor film 113 halfway in the thickness direction. It is possible to easily manufacture a light control element that can be driven at high speed at high speed.

In the above SL, comb teeth 51A~51D comb 41A~41D and rotation-side electrode 50A~50D of the fixed side electrode 40A~40D is disposed perpendicularly to the longitudinal direction of the support portion 20 Although the example has been described, as shown in FIG. 20, the comb teeth 41 </ b> A to 41 </ b> D and the comb teeth 51 </ b> A to 51 </ b> D may be arranged in parallel to the longitudinal direction of the support portion 20. In this configuration, the comb teeth 41 </ b> A to 41 </ b> D and 51 </ b> A to 51 </ b> D in the vicinity of the support portion 20 are not spaced apart from each other even when the rotation angle of the movable member 10 is increased. can do.

First Embodiment
FIG. 21 shows the flow of the manufacturing method of the light control element according to the first embodiment of the present invention, and FIGS. 22 to 25 show the process. In this manufacturing method, the crosspiece structure 11 is formed by selectively forming a semiconductor growth layer in a part of the movable member formation scheduled region 10A on the semiconductor film 113. This is the manufacturing method described in the above reference example. Is different. Therefore, the configuration of each part is the same as that in the above-described reference example, and corresponding components are denoted by the same reference numerals and will be described below. Note that FIG. 22 to FIG. 25, II in FIG. 1 - shows a cross-section taken along the line II.

  First, an SOI substrate 110 is prepared as shown in FIG. This SOI substrate 110 has a structure in which an oxide layer 112 made of silicon dioxide having a thickness of, for example, 1 μm and a semiconductor film 113 made of silicon having a thickness of, for example, 0.3 μm are sequentially stacked on the surface of a holding substrate 111 made of silicon. Is. Here, the volume resistance value of the semiconductor film 113 is preferably as low as possible. For example, antimony (Sb) is preferably added.

  Next, as shown in FIG. 22B, the semiconductor film 113 is selectively removed, for example, by a deep RIE method, leaving a region to be formed such as the movable member 10 (step S201).

  Subsequently, as shown in FIG. 22C, a mask layer 150 made of silicon dioxide and having a thickness of 20 μm is formed on the semiconductor film 113 using low stress TEOS (tetraethoxy silane) or the like. The mask layer 150 in the region where the crosspiece structure 11 or the like is to be formed is selectively removed.

  After selectively removing the mask layer 150, as shown in FIG. 23A, a semiconductor growth layer 160 made of silicon, for example, is selectively formed in an area where the crosspiece structure 11 or the like is to be formed by, eg, epitaxial growth. By doing so, the crosspiece structure 11 is formed (step S202). At this time, the semiconductor growth layer 160 is also selectively formed in the regions where the support portion 20, the outer frame portion 30, the fixed side electrodes 40A to 40D and the rotation side electrodes 50A to 50D are to be formed. A sufficient thickness can be secured.

  After the crosspiece structure 11 is formed, as shown in FIG. 23B, insulating films 81 made of silicon nitride are formed on both surfaces of the SOI substrate 110, and the insulating film on the holding substrate 111 side is formed by, for example, photolithography. At least the movable member formation scheduled area 10A of 81 is selectively removed (step S203). Here, for example, the insulating film 81 on the holding substrate 111 side is selectively removed leaving a region where the outer frame portion 30 is to be formed.

  Subsequently, as shown in FIG. 23C, at least the movable member formation scheduled region of the holding substrate 111 by anisotropic etching using the insulating film 81 on the holding substrate 111 side as a mask and TMAH as an etching solution. 10A is selectively removed to the middle in the thickness direction (step S204). Here, for example, the holding substrate 111 is selectively removed halfway in the thickness direction, leaving a region where the outer frame portion 30 is to be formed. The remaining thickness of the holding substrate 111 is, for example, 100 μm.

  After removing the holding substrate 111 halfway in the thickness direction, as shown in FIG. 24A, a polysilicon film having a thickness of 10 μm for forming the activation electrode 80 on the insulating film 81 on the semiconductor film 113 side. 170 is formed. After that, as shown in FIG. 24B, the activation electrode 80 is formed by patterning the polysilicon film 170 by, for example, the deep RIE method (step S205).

  After forming the activation electrode 80, as shown in FIG. 24C, the SOI substrate 110 is cut by, for example, dicing, and a plurality of movable member formation scheduled regions 10A provided on the SOI substrate 110 are individually cut. (Step S206). At this time, since a part of the holding substrate 111 in the thickness direction is left, the strength is ensured, and the possibility of damage due to dicing can be eliminated.

  After individually separating the plurality of movable member formation scheduled regions 10A, as shown in FIG. 25A, anisotropic etching using the insulating film 81 on the holding substrate 111 side as a mask and TMAH as an etchant is performed. Then, the holding substrate 111 is removed to the end in the thickness direction (step S207).

After removing the holding substrate 111, as shown in FIG. 25B, at least the movable member formation scheduled region 10A is selectively selected from the oxide layer 112 and the mask layer 150 by wet etching using BHF as an etchant. The movable member 10, the support part 20, the outer frame part 30, the fixed side electrodes 40A to 40D and the rotation side electrodes 50A to 50D are formed (step S208). Here, for example, the oxide layer 112 and the mask layer 150 are selectively removed leaving a region where the outer frame portion 30 is to be formed. At that time, the insulating film 81 is removed leaving only a portion sandwiched between the activation electrode 80 and the outer frame portion 30. After the etching is completed, critical drying is performed in the same manner as in the above reference example .

After removing the oxide layer 112, the mask layer 150, and the insulating film 81, as shown in FIG. 25C, the reflective film 100 is formed on the movable member 10 in the same manner as in the above reference example (step S209). Thus, the light control element shown in FIG. 21 is completed.

  As described above, in the present embodiment, since the crosspiece structure 11 is formed by selectively forming the semiconductor growth layer 160 in a part of the movable member formation scheduled region 10A on the semiconductor film 113, the rigidity is high. A light control element capable of high-speed driving can be easily formed.

Second Embodiment
FIG. 26 shows the overall configuration of the light control element according to the second embodiment of the present invention. This light control element has the same configuration as that of the above-described reference example except that the activation electrode 80 is not provided and the function is provided to the drive power supply 60. Therefore, the corresponding components are denoted by the same reference numerals and will be described below.

  In the present embodiment, the control unit 70 activates the movable member 10 in a neutral state by an AC voltage from the driving power supply 60 to activate the movable member 10 in a self-excited manner. As a result, this light control element does not require the activation electrode 80 and can be easily manufactured with a simpler configuration.

  This light control element can be manufactured as follows, for example.

FIG. 27 shows the flow of the manufacturing method of the light control element, and FIGS. 28 to 31 show the steps in order. Note that portions where the reference example and the manufacturing process overlap will be described with reference to FIGS. 7A and 7B.

7A, an SOI substrate 110 in which an oxide layer 112 and a semiconductor film 113 are sequentially stacked on the surface of the holding substrate 111 is prepared in the same manner as described above .

Next, by the process shown in FIG. 7B, the insulating film 81 is formed on both surfaces of the SOI substrate 110 in the same manner as described above, and the insulating film 81 on the semiconductor film 113 side is to be formed as the crosspiece structure 11 or the like. While selectively removing the region, at least the movable member formation scheduled region 10A in the insulating film 81 on the holding substrate 111 side is selectively removed (step S101). Here, for example, the insulating film 81 on the holding substrate 111 side is selectively removed leaving a region where the outer frame portion 30 is to be formed.

  Subsequently, as shown in FIG. 28A, a photoresist film 130 is formed on the insulating film 81 on the semiconductor film 113 side in a region where the movable member 10 and the like are to be formed.

  After the formation of the photoresist film 130, as shown in FIG. 28B, the semiconductor film 113 is left in a region where the movable member 10 and the like are to be formed by, for example, deep RIE using the photoresist film 130 as a mask. Then, it is selectively removed partway along the thickness direction (step S103). At this time, the thickness of the semiconductor film 113 to be removed is set to about 1 μm, for example.

After removing the semiconductor film 113 halfway in the thickness direction, the photoresist film 130 is removed as shown in FIG. Next, as shown in FIG. 29A, using the insulating film 81 on the semiconductor film 113 side as a mask, the region of the semiconductor film 113 that has been removed to the middle in the thickness direction, for example, by the deep RIE method is used as the last in the thickness direction. And the crosspiece structure 11 is formed by selectively removing a part of the movable member formation scheduled region 10A to the middle in the thickness direction (step S104). At this time, it is preferable to detect the thickness by measuring the reflectance of the semiconductor film 113 as in the above reference example .

  After the crosspiece structure 11 is formed, the surface of the SOI substrate 110 is covered with a protective film 140 made of a photoresist as shown in FIG. Subsequently, as shown in FIG. 30A, the SOI substrate 110 is cut by, for example, dicing, and a plurality of movable member formation scheduled regions 10A provided on the SOI substrate 110 are individually separated (step S105).

  After individually separating the plurality of movable member formation scheduled regions 10A, as shown in FIG. 30B, the insulating film 81 on the holding substrate 111 side is used as a mask, and anisotropic etching using TMAH as an etching solution is performed. Then, at least the movable member formation scheduled area 10A of the holding substrate 111 is selectively removed (step S106). Here, for example, the holding substrate 111 is selectively removed leaving a region where the outer frame portion 30 is to be formed.

After removing the holding substrate 111, the protective film 140 made of a photoresist is removed as shown in FIG. Subsequently, as shown in FIG. 31B, at least the movable member formation scheduled region 10A of the oxide layer 112 is selectively removed by wet etching using BHF as an etchant, and the movable member 10 and the support portion are removed. 20, outer frame portion 30, fixed side electrodes 40A to 40D, and rotation side electrodes 50A to 50D are formed (step S107). Here, for example, the oxide layer 112 is selectively removed leaving a region where the outer frame portion 30 is to be formed. At that time, the insulating film 81 is removed leaving only a portion sandwiched between the activation electrode 80 and the outer frame portion 30. After completion of etching, critical drying is performed in the same manner as described above .

After removing the oxide layer 112 and the insulating film 81, as shown in FIG. 31C, the reflective film 100 is formed on the movable member 10 in the same manner as described above (step S108). Thus, the light control element shown in FIG. 27 is completed.

In this light control element, since the crosspiece structure 11 is provided on the back surface of the movable member 10 as described above , the movable member 10 can be thinned to reduce the moment of inertia, and the resonance frequency can be increased. . Moreover, the movable member 10 is reinforced by the crosspiece structure 11, and the flatness at the time of rotation becomes high. Therefore, light is controlled at high speed and with high accuracy.

  In this light control element, the driving power source 60 is turned on when the movable member 10 is in a stationary state. As a result, a voltage having a resonance frequency of the movable member 10 or a drive frequency that is a multiple or a fraction of the resonance frequency is applied between the rotating side electrodes 50A to 50D and the fixed side electrodes 40A to 40D. Begins to vibrate self-excited.

When the self-excited vibration is started, the vibration of the movable member 10 is increased and the rotation angle is increased. Subsequent control by the control unit 70 is the same as in the reference example .

As described above, in the present embodiment, the drive power supply 60 is provided with the function of the start-up power supply 90 of the above reference example , so that the self-excited vibration of the movable member 10 can be generated with a simple configuration. There is an effect.

In the present embodiment, the case where the light control element having the crosspiece structure 11 is manufactured by the manufacturing method of the reference example has been described. However, the light control element may be manufactured by the manufacturing method of the first embodiment.

[ Third Embodiment]
FIG. 32 shows the overall configuration of the light control element according to the third embodiment of the present invention, and FIG. 33 shows its cross-sectional configuration. The light control element is configured to couple the movable member 10 by the support portion 20 relative to the outer frame portion 30, except that it has connected to the fixed portion 230 of the outer frame portion 30 by an outer frame support section 220, the reference It has the same configuration as the example . In the following description, corresponding components are denoted by the same reference numerals.

The movable member 10, the crosspiece structure 11, the support portion 20, and the reflective film 100 have the same configuration as that of the reference example .

  The first fixed side electrodes 40A to 40D are connected to the outer frame portion 30, and the first rotation side electrodes 50A to 50D are provided corresponding to each of the first fixed side electrodes 40A to 40D.

  In the present embodiment, the outer frame portion 30 is provided so as to surround the movable member 10 and is formed of a semiconductor film in which the holding substrate and the oxide layer are selectively removed from the same SOI substrate as the movable member 10. .

Further, in the same manner as described above , the light control element includes a first driving power source 60 that applies a voltage for electrostatic driving between the first rotation side electrodes 50A to 50D and the first fixed side electrodes 40A to 40D. And a control unit 70 for controlling the first driving power source 60, an activation electrode 80 for starting activation of the movable member 10, and a connection between the activation electrode 80 and the movable member 10. And a first startup power supply 90. In FIG. 19 and FIG. 20, the first driving power source 60, the control unit 70, the starting electrode 80, and the first starting power source 90 are omitted.

  The outer frame support unit 220 arranged in a direction orthogonal to the support unit 20 is a torsion beam similar to the support unit 20, and the outer frame unit 30 is orthogonal to the drive direction of the movable member 10 at one end thereof. It is supported so that it can rotate. The outer frame support part 220 is also composed of a semiconductor film together with the movable member 10 after removing the holding substrate and the oxide layer from the same SOI substrate.

  The other end side of the outer frame support part 220 is fixed to the fixing part 230. The fixed portion 230 is formed of the same SOI substrate together with the movable member 10, and has a structure in which another film is formed as necessary. Note that the fixing portion 230 does not necessarily need to surround the entire outer frame portion 30, and may be provided at least at a fixing position of the outer frame support portion 220.

  Further, the light control element includes an outer frame driving unit 200 for driving the outer frame unit 30. Thereby, in this light control element, the movable member 10 can be displaced in a two-dimensional direction.

  The outer frame driving unit 200 includes second fixed-side electrodes 240A, 240B, 240C, and 240D and second rotating-side electrodes 250A, 250B, 250C, and 250D. The driving speed of the outer frame part 30 by the outer frame driving part 200 may be lower than the driving speed of the movable member 10.

  The second fixed-side electrodes 240A to 240D are connected to the fixed portion 230 and have a plurality of comb teeth 241A, 241B, 241C, and 241D, respectively. These second fixed-side electrodes 240 </ b> A to 240 </ b> D are formed on the flat surface of the semiconductor film after removing the holding substrate and the oxide layer from the same SOI substrate together with the movable member 10.

  The second rotation side electrodes 250 </ b> A to 250 </ b> D are disposed on both sides of each of the two outer frame support portions 220 corresponding to the second fixed side electrodes 240 </ b> A to 240 </ b> D. These second rotation-side electrodes 250A to 250D are connected to the outer frame portion 30 and have a plurality of comb teeth 251A to 251D corresponding to the comb teeth 241A to 241D. The second rotating side electrodes 250A to 250D have the same structure as the second fixed side electrodes 240A to 240D.

The second rotation side electrodes 250A to 250D are also in the same plane as the second fixed side electrodes 240A to 240D in the neutral position, and there is no step between them, as in the above reference example . Accordingly, the second fixed side electrodes 240A to 240D and the second rotation side electrodes 250A to 250D, and the first fixed side electrodes 40A to 40D and the first rotation side electrodes 50A to 50D can be manufactured in the same process. The manufacturing process can be greatly simplified as compared with the conventional vertical comb type.

Further, although not shown, the light control element includes a second driving power source that applies a high-frequency voltage between the second rotation side electrodes 250A to 250D and the second fixed side electrodes 240A to 240D, and the outer frame portion 30. And a second starting power source for applying a starting dust voltage between the starting electrode and the outer frame portion 30. The second driving power source and the second starting power source are controlled to be turned on / off through the control unit 70 in the same manner as the first driving power source and the first starting power source. Because the basic principle is the same as that described in Reference Example, description will be omitted.

This light control element is the same process as the first fixed side electrodes 40A to 40D and the first rotation side electrodes 50A to 50D, and the outer frame support part 220, the outer frame part 30, the second fixed side electrode 240A. ˜240D and the second rotation side electrodes 250A to 250D can be manufactured in the same manner as in the reference example or the first embodiment except that they are formed.

  In the present embodiment, the movable member 10 is rotated and displaced in one direction by the first fixed side electrodes 40A to 40D and the first rotation side electrodes 50A to 50D, and the second fixed side electrodes 240A to 240D and the second time. The outer side frame portion 30 is displaced in a direction orthogonal to the rotational direction of the movable member 10 by the moving side electrodes 250A to 250D. Thereby, the movable member 10 is displaced in a two-dimensional direction.

  As described above, in this embodiment, the outer frame support portion 220 connected to the outer frame portion 30 is a torsion beam, and the outer frame portion 30 is rotationally displaced together with the movable member 10 about this as a shaft. 10 can be displaced in a two-dimensional direction.

  Hereinafter, specific application examples of the light control element of the present invention will be described.

  FIG. 34 shows an example of a display device using the light control element of the present invention. In this display device, light from the light source 310 is reflected by the light control element 320 and projected onto the screen 330 as an image P. An optical modulator 340 is provided between the light source 310 and the light control element 320.

  The light source 310 is preferably composed of, for example, a laser or a light emitting diode. This is because a laser or a light emitting diode is close to a point light source and has a high light density, so that a beam with a small diameter is easily obtained.

The light control element 320 includes the light control element described in the third embodiment. As a result, this display device can perform high-speed two-dimensional driving, and can display an NTSC or high-definition image by scanning one light.

  The optical modulator 340 is for superimposing the video signal on the optical signal from the light source 310.

  In this display device, the light from the light source 310 is superimposed on the video signal by the light modulator 330 and then input to the light control element 320, where it is scanned on the screen 340 by the movable member 10 of the present invention. Thereby, the video P is displayed.

  As described above, in the present embodiment, since the light control element of the present invention is provided, high-speed two-dimensional driving is possible, and NTSC and high-definition images can be displayed by scanning one light. it can.

  The present invention has been described with reference to the embodiment. However, the present invention is not limited to the above embodiment, and various modifications can be made. For example, in the above-described embodiment, the configurations of the light control element and the display device have been specifically described, but the configurations of the light control element and the display device are not limited to the above-described embodiment. For example, the shape of the movable member 10 is not limited to a rectangular shape, and may be any other shape.

For example, the third embodiment can be applied not only to the light control element of the reference example but also to the light control element of the second embodiment.

Furthermore, for example, in the third embodiment, the second driving unit 200 may use a driving method other than an electrostatic force such as electromagnetic force or thermal driving.

  In addition, for example, the material and thickness of each layer described in the above embodiment, the film formation method and the film formation conditions are not limited, and other materials and thicknesses may be used, or other film formation methods. Alternatively, film forming conditions may be used. For example, in the above embodiment, potassium hydroxide (KOH), hydrazine, ethylenediamine-pyrocatechol-water (EPW) or the like can be used instead of TMAH.

  Furthermore, for example, in the above-described embodiment, the galvanometer mirror that is driven by electrostatic force is described as an example of the movable member 10, but other mirrors such as a polygon mirror (rotating polygon mirror) may be used. Furthermore, the present invention is not limited to the mirror as the movable member 10 and can be widely applied to driving devices that require high-speed displacement such as gyros.

  In addition, for example, in the above-described embodiment, the light control element of the present invention can be applied to an image display, a scanner, and the like. However, the present invention can be applied to, for example, a micro bar code reader, a beam scanner, a laser printer, an optical switch. , Projector, laser scanner for laser show, display, two-dimensional barcode reader, distance sensor, laser sonar, confocal microscope, laser microscope, stereolithography prototyping, laser processing machine, PtoP (peer-to-peer) optical communication, optical The present invention can be widely applied to other electronic devices such as communication.

It is a top view showing an example of the whole structure of the light control element concerning a reference example . It is sectional drawing in the II-II line | wire of the light control element shown in FIG. It is the perspective view showing the structure which looked at the movable member and support part which were shown in FIG. 1 from the back surface side of the movable member. It is sectional drawing in the IV-IV line of the light control element shown in FIG. It is a figure showing the equivalent circuit of FIG. It is a figure showing the flow of the manufacturing method of the light control element shown in FIG. FIG. 3 is a cross-sectional view illustrating a method for manufacturing the light control element illustrated in FIG. 1 in the order of steps. It is sectional drawing for demonstrating the process following the process of FIG. FIG. 9 is a cross-sectional view for explaining a process following the process of FIG. 8. FIG. 10 is a cross-sectional view for explaining a process following the process of FIG. 9. It is sectional drawing for demonstrating the process following the process of FIG. It is sectional drawing for demonstrating the process following the process of FIG. It is a figure for demonstrating the method to detect the thickness of a semiconductor film in the process shown to FIG. 10 (A). It is a figure for demonstrating the starting method of the light control element shown in FIG. It is a figure for demonstrating the starting method of the light control element shown in FIG. It is a figure for demonstrating operation | movement of the light control element shown in FIG. It is a figure for demonstrating operation | movement of a light control element similarly. It is a figure for demonstrating operation | movement of a light control element similarly. It is a figure for demonstrating operation | movement of a light control element similarly. FIG. 6 is a plan view illustrating another configuration of the light control element illustrated in FIG. 1. It is a figure showing the flow of the manufacturing method of the light control element which concerns on the 1st Embodiment of this invention. FIG. 22 is a cross-sectional view illustrating the manufacturing method illustrated in FIG. 21 in the order of steps. FIG. 23 is a cross-sectional view for explaining a process following the process of FIG. 22. FIG. 24 is a cross-sectional view for illustrating a process following the process in FIG. 23. FIG. 25 is a cross-sectional view for explaining a process following the process in FIG. 24. It is a top view showing an example of the whole structure of the light control element concerning a 2nd embodiment of the present invention. It is a figure showing the flow of the manufacturing method of the light control element shown in FIG. FIG. 27 is a cross-sectional view showing a method of manufacturing the light control element shown in FIG. 26 in the order of steps. FIG. 29 is a cross-sectional view for explaining a process following the process in FIG. 28. FIG. 30 is a cross-sectional view for explaining a process following the process of FIG. 29. FIG. 31 is a cross-sectional view for explaining a process following the process of FIG. 30. It is a top view showing an example of the whole structure of the light control element concerning a 3rd embodiment of the present invention. It is sectional drawing in the XXXIII-XXXIII line of the light control element shown in FIG. It is a perspective view showing an example of the display apparatus provided with the light control element of the present invention. It is a perspective view showing an example of the conventional movable member.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Movable member, 11 ... Crosspiece structure, 20 ... Support part, 30 ... Outer frame part, 40A-40D ... Fixed side electrode, 1st fixed side electrode, 41A-41D, 51A-51D, 241A-241D, 251A-251D ... comb teeth, 50A to 50D ... rotating side electrode, first rotating side electrode, 60 ... driving power source, 70 ... control unit, 80 ... starting electrode, 81 ... insulating film, 90 ... starting power source, 100 ... Reflective film, 110 ... SOI substrate, 111 ... holding substrate, 112 ... oxide layer, 113 ... semiconductor film, 200 ... outer frame drive unit, 220 ... outer frame support unit, 230 ... fixing unit, 240A to 240D ... second fixed side Electrode, 250A to 250D ... second rotation side electrode, 310 ... light source, 320 ... light control element, 330 ... screen, 340 ... light modulator

Claims (3)

A plate-shaped movable member having a reflective surface on the surface, an outer frame member that rotatably supports the movable member, and the movable member and the outer frame member are connected to each other at positions opposite to each other. And a method for manufacturing a light control element comprising a pair of support portions that serve as pivot axes of the movable member ,
And between the oxide layer on the holding substrate using a substrate having a semiconductor film, selectively removing the other regions leaving the movable member, forming region of the support and the outer frame member of said semiconductor film And a process of
By selectively forming the semiconductor growth layer on a part of the variable rotary members forming region on the semiconductor film, a step of桟幅on the back surface of the movable member forms a more crosspiece structure 3 [mu] m,
Forming the movable member and the outer frame member by selectively removing at least the movable member formation scheduled region of the holding substrate and the oxide layer. When selectively removing the holding substrate, it is divided into a plurality of times, and before the final round is performed, the substrate is cut to separately form a plurality of movable member formation scheduled regions provided on the substrate. The method for manufacturing a light control element according to claim 1. The method for manufacturing a light control element according to claim 1, wherein after the holding substrate is selectively removed, a reflective film is formed on the other surface of the movable member.

Images