JP4087918B2 - Integrated optical unit - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an integrated optical unit used in an optical pickup device that records or reproduces information on or from an optical recording medium, particularly to optical recording media having different recording densities using a common semiconductor laser and optical system. The present invention relates to an integrated optical unit suitable for use in recording and reproducing information.
[0002]
[Prior art]
As an optical pickup device for recording and reproducing information with respect to disks having different recording densities, for example, Japanese Patent Laid-Open No. 6-124477 discloses a ring-shaped electrode in a parallel optical path between a laser light source and an objective lens. A liquid crystal filter and a polarizing beam splitter are arranged, and the polarization state of the laser light transmitted through the ring-shaped electrode portion is selectively changed by the liquid crystal filter in accordance with the recording density of the disk to be recorded / reproduced. By reflecting the transmitted light with a polarizing beam splitter, the diameter of the light beam incident on the objective lens via the polarizing beam splitter, that is, the numerical aperture is large for a high-density recording disk, and the low-density recording disk. On the other hand, what was made small is disclosed.
[0003]
Japanese Patent Laid-Open No. 6-20298 discloses a light beam incident on an objective lens in the same manner according to the recording density of a disk to be recorded / reproduced by providing mechanical variable aperture means in the optical path of the optical system. The diameter of the disk, that is, the numerical aperture, is large for a disk on which high density recording is performed, and is small for a disk on which low density recording is performed.
[0004]
[Problems to be solved by the invention]
By the way, in recent optical pickup devices, in order to reduce the size and weight of the device, the semiconductor laser and the photodetector are mounted in a package in a chip state and hermetically sealed. This makes it possible to reduce the size and weight of the apparatus, effectively prevent dust and the like from being attached, and provide a lead terminal for wiring on the package, thereby facilitating wiring processing.
[0005]
Therefore, it is conceivable to control the numerical aperture of the objective lens by mounting the liquid crystal filter disclosed in the above-mentioned JP-A-6-124477 in a package together with the semiconductor laser and the photodetector. However, in this case, since the liquid crystal filter is disposed in the diverging optical path of the light beam emitted from the semiconductor laser, there arises a problem that desired optical characteristics cannot be obtained due to the incident angle dependency of the liquid crystal filter. It will be.
[0006]
Similarly, it is conceivable that the mechanical variable aperture means disclosed in the above-mentioned JP-A-6-20298 is mounted in a package together with a semiconductor laser and a photodetector to reduce the size. It is extremely difficult to provide such a mechanical variable aperture means in a small package. For this reason, an increase in the size of the package is unavoidable, and there arises a problem that the entire apparatus cannot be reduced in size.
[0007]
The present invention has been made in view of the above-described problems, and can be reduced in size and appropriately configured to control the diameter of a light beam emitted from a semiconductor laser without affecting desired optical characteristics. An object of the present invention is to provide an integrated optical unit.
[0008]
[Means for Solving the Problems]
  The invention according to claim 1, which achieves the above object, provides a semiconductor laser that generates a light beam for irradiating an optical recording medium, a photodetector that receives return light from the optical recording medium, and irradiates the optical recording medium. Separating the light beam to be transmitted and the return light from the optical recording mediumHologram elementIn an integrated optical unit that is mounted in a package,
  A semiconductor substrate having a reflective surface and a recess formed by etching;
  The semiconductor laser is, The diverging light beam is disposed in the recess so as to enter the hologram element through the reflecting surface,
  On the surface of the semiconductor substrate, in the vicinity of the reflective surface,A bearing, a rotor that can be rotated electrostatically or electromagnetically with respect to the bearing, and a light beam that is formed on the rotor and diverges from the semiconductor laser isThrough the reflective surfaceControl the diameter of the light beam by selectively positioning at the incident positionTo enter the hologram elementA diaphragm having a plurality of openings of different sizes forIn addition, the photodetector is provided at a position off the diaphragm so as to receive the return light from the optical recording medium separated by the hologram element without passing through the diaphragm.It is characterized by that.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
  1 and 2 show the present invention.Reference example of integrated optical unit developed togetherIt is the schematic sectional drawing and schematic partial perspective view which show. thisReference exampleIrradiates the optical recording medium 3 with the light beam from the integrated optical unit 1 through the objective lens 2 and causes the return light to enter the integrated optical unit 1 through the objective lens 2 to record or reproduce information. In this case, the diameter of the light beam incident on the objective lens 2 from the integrated optical unit 1, that is, the numerical aperture of the objective lens 2, is recorded according to the type of the optical recording medium 3, that is, the recording density. The optical recording medium 3 is controlled to be large in the case of 3, and small in the case of the optical recording medium 3 on which low density recording is performed.
[0011]
The integrated optical unit 1 is provided with a semiconductor laser 6, an electrostatic diaphragm 7, a beam splitter 8, and a semiconductor substrate 9 housed in a package 5. The package 5 includes a stem 12 made of ceramic or the like provided with a plurality of lead terminals 11, and a cap 14 having a hologram element 13 having a hologram pattern 13a having a slight curvature on the surface.
[0012]
The semiconductor substrate 9 is fitted and fixed in a recess formed in the stem 12. The semiconductor substrate 9 includes a light receiving region 15 for detecting the amount of light emitted from the semiconductor laser 6, a light receiving unit 16 for detecting an information signal from the return light from the optical recording medium 3, and a focus error signal from the return light. Two light receiving portions 17 and 18 for detecting the tracking error signal are formed. The light receiving unit 16 includes two light receiving regions 16a and 16b, and the light receiving units 17 and 18 are each divided into three light receiving regions 17a, 17b and 17c by dividing lines in a direction parallel to the track of the optical recording medium 3. 18a, 18b, and 18c.
[0013]
  Further, the semiconductor substrate 9 is formed with a rising portion 9a at one end thereof, the semiconductor laser 6 is fixed on the upper surface thereof, and the diverging light beam emitted from the semiconductor laser 6 is passed through the electrostatic diaphragm 7. Then, the light is incident on the beam splitter 8. In addition, thisReference exampleThen, the anode of the semiconductor laser 6 and the cathode of each light receiving region formed on the semiconductor substrate 9 are connected to a common predetermined lead terminal 11.
[0014]
  The beam splitter 8 is configured by bonding a glass prism 21 having a right isosceles triangle and a uniaxial birefringent crystal prism 22 made of, for example, lithium niobate through a polarizing film 23, and the uniaxial birefringent crystal prism 22 is formed. The semiconductor substrate 9 is provided so as to be positioned on the light receiving regions 15 and 16 formed on the semiconductor substrate 9. In addition, thisReference exampleThen, the polarizing film 23 is configured so that the reflectance of the S polarization component is 50% or more and the transmittance of the P polarization component is 80% or more.
[0015]
The electrostatic diaphragm 7 is provided by adhering to the surface of the glass prism 21 on which the light beam from the semiconductor laser 6 is incident, and the diameter of the diverging light beam from the semiconductor laser 6 incident on the glass prism 21, that is, the objective lens 2. The numerical aperture is configured to be controlled according to the recording density of the optical recording medium 3. The configuration of the electrostatic diaphragm 7 and the formation process thereof will be described later.
[0016]
  thisReference exampleThen, the diverging light beam from the semiconductor laser 6 is controlled by the electrostatic aperture 7 according to the type of the optical recording medium 3 and is incident on the polarizing film 23 through the glass prism 21 as S-polarized light. . As described above, when the light is incident as S-polarized light, the polarizing film 23 has a characteristic that the reflectance of the S-polarized component is 50% or more and the transmittance of the P-polarized component is 80% or more. Then, it enters the hologram pattern 13 a of the hologram element 13. The light beam from the semiconductor laser 6 incident on the hologram pattern 13 a irradiates the optical recording medium 3 as a spot with the 0th-order light by the objective lens 2. The light beam from the semiconductor laser 6 that has passed through the polarizing film 23 and entered the uniaxial birefringent crystal prism 22 is reflected by the inclined surface of the uniaxial birefringent crystal prism 22 and formed on the semiconductor substrate 9. Light is received in the region 15 and the output of the semiconductor laser 6 is controlled based on the output.
[0017]
The return light reflected by the optical recording medium 3 enters the hologram pattern 13a of the hologram element 13 through the objective lens 2 and is separated into 0th order light and ± 1st order diffracted light. Here, the ± first-order diffracted light is given image point movements opposite to each other in the direction of the optical axis by the action of the hologram pattern 13a having a slight curvature. The light is received by the unit 17 and the other is received by the light receiving unit 18.
[0018]
Therefore, each output of the light receiving regions 17a to 17c of the light receiving unit 17 is expressed as I._17a~ I_17c, The output of each of the light receiving regions 18a to 18c of the light receiving unit 18 is I_18a~ I_18cThen, the focus error signal FES is obtained by using the beam size method.
FES = (I_17a+ I_18b+ I_17c)-(I_18a+ I_17b+ I_18c)
Can be obtained. Further, the tracking error signal TES is obtained by a push-pull method.
TES = (I_17a+ I_18c)-(I_17c+ I_18a)
Can be obtained.
[0019]
  Also hologrampatternThe return light from the optical recording medium 3 that passes through the light 13 a with 0th-order light is incident on the polarizing film 23 again through the glass prism 21. Here, when the optical recording medium 3 is, for example, a magneto-optical recording medium, the information is recorded as the magnetization direction, so the polarization direction of the return light is slightly rotated in the opposite direction according to the magnetization direction. Will be. Therefore, the return light incident on the polarizing film 23 includes a P-polarized component. Due to the action of the polarizing film 23, the return light from the optical recording medium 3 is refracted and transmitted through the uniaxial birefringent crystal prism 22 by less than 50% of the S-polarized component and 80% or more of the P-polarized component. Separated into light.
[0020]
The ordinary light and the extraordinary light emitted from the uniaxial birefringent crystal prism 22 are received by the light receiving region 16 a and the light receiving region 16 b of the light receiving unit 16 formed on the semiconductor substrate 9, respectively. Here, the uniaxial birefringent crystal prism 22 is provided with its optical axis inclined at 45 ° with respect to the S-polarization direction in a plane perpendicular to the optical axis of the return light. Accordingly, the polarization direction of the return light changes with respect to the optical axis of the uniaxial birefringent crystal prism 22, and the intensity of ordinary light and abnormal light changes. By detecting at 16b, a magneto-optical signal corresponding to the information recorded on the optical recording medium 3 can be obtained. That is, the output of each of the light receiving regions 16a and 16b is expressed as I_16a, I_16bThen, the magneto-optical signal S is
S = I_16a-I_16b
Can be obtained.
[0021]
When the optical recording medium 3 is a reproduction-only DVD or CD, for example, an information signal is obtained from the sum of the outputs of the light receiving areas 16a and 16b or the sum of the outputs of the light receiving areas of the light receiving sections 17 and 18. be able to.
[0022]
Next, the configuration of the electrostatic diaphragm 7 shown in FIGS. 1 and 2 and the formation process thereof will be described.
FIGS. 3A and 3B are a plan view and a cross-sectional view showing a configuration of an example of the electrostatic diaphragm 7. The electrostatic diaphragm 7 has a rotor 51 made of polycrystalline silicon, for example, having an outer diameter of 140 μm. In the rotor 51, for example, circular openings 52 and 53 having a diameter of 45 μm and 30 μm, for example, are formed on a circumference having a diameter of 100 μm, with a central angle of 45 °, for example.
[0023]
The rotor 51 is supported at the center by a bearing 54 and is formed so as to be rotatable about the bearing 54 with respect to the single crystal silicon substrate 59. Two rotor electrodes 55 and 56 are provided on the periphery of the rotor 51. Each is formed so as to cover a range of 60 ° at the central angle. In addition, on the single crystal silicon substrate 59, two stator electrodes 57 and 58 are similarly formed on the outer side of the rotor electrodes 55 and 56 so as to cover a range of 60 ° at the central angle. The rotor electrodes 55 and 56 and the stator electrodes 57 and 58 are configured such that the rotor electrode 55 and the stator electrode 57, and the rotor electrode 56 and the stator electrode 58 are selectively opposed to each other and the rotor 51 is rotated 45 degrees in the forward and reverse directions. To form a positional relationship.
[0024]
Further, the single crystal silicon substrate 59 has a rectangular through hole 60 whose opening area decreases toward the rotor 51 so that the center thereof selectively coincides with the centers of the openings 52 and 53 formed in the rotor 51. Form. The through hole 60 is formed so that the cross section thereof is trapezoidal, the four side surfaces of the hole are inclined, and the opening area facing the rotor 51 is larger than the area of the opening 52. Further, on the single crystal silicon substrate 59, a GND electrode 63 that is substantially opposed to the lower surface of the rotor 51 and serves as a reference potential when a voltage is applied to the stator electrode 57 or 58 is formed in conduction with the rotor 51. .
[0025]
Next, an example of the process of forming the electrostatic diaphragm 7 will be described with reference to FIGS. The electrostatic diaphragm 7 is formed by using a method called surface micromachining. First, as shown in FIG. 4A, a single crystal silicon substrate 59 having a (100) surface is used, and a silicon nitride thin film 61 is formed on the surface by low pressure chemical vapor deposition (LPCVD), for example, to a thickness. 0.45 μm is formed. In LPCVD, since a silicon nitride thin film is formed on both the front surface and the back surface of the substrate, the back side silicon nitride thin film is denoted by reference numeral 61 '. Here, the silicon nitride thin film 61 on the front surface side serves as an insulating film between the single crystal silicon substrate 59 and the electrostatic diaphragm structure, and the silicon nitride thin film 61 ′ on the back surface side serves as an etching mask when the through hole 60 is formed. Become.
[0026]
Thereafter, a polycrystalline silicon thin film 62 is formed on the silicon nitride thin film by LPCVD, for example, to a thickness of 0.2 μm, and its conductivity is improved by doping with phosphorus or boron. The polycrystalline silicon thin film 62 becomes the GND electrode 63 and is patterned as shown in FIG. Since this patterning does not require any particular precision, it is performed, for example, by wet etching, and at the same time, a polycrystalline silicon thin film (not shown) formed on the back side is removed.
[0027]
Next, in order to form the through hole 60 in the single crystal silicon substrate 59, the silicon nitride film 61 'on the back surface side is patterned into a square so as to be parallel to the (111) plane, and an etchant such as KOH, EDP, TMAH or the like is formed. Is used to carry out anisotropic etching of the single crystal silicon substrate 59. At this time, the etching rate of the (111) plane of the single crystal silicon substrate 59 is considerably slow with respect to other plane orientations, and the etching proceeds so that the (111) plane is exposed. Thus, four slopes are formed and the cross-sectional shape is trapezoidal. In this anisotropic etching, when the single crystal silicon substrate 59 is penetrated, the silicon nitride thin film 61 becomes an etch stop, and the etching stops.
[0028]
Subsequently, as shown in FIG. 4C, a silicon oxide thin film 64 to be a sacrificial layer later is formed by LPCVD, for example, with a thickness of 3 μm, and the front side is masked with a photoresist, and the back side silicon oxide thin film is wet. Remove with etch. Further, after etching the portion of the silicon nitride thin film 61 serving as an etch stop of the through hole 60 from the back side and the silicon nitride thin film 61 ′ serving as the back side etching mask with phosphoric acid, the polycrystalline in the through hole 60 is obtained. The silicon thin film 62 is wet etched. Thereafter, the stator electrode on the substrate surface side and the fixed portion of the rotor central axis to the substrate are patterned by dry etching.
[0029]
Next, as shown in FIG. 4D, a polycrystalline silicon film 65 is formed with a thickness of, for example, 5 μm by LPCVD, and its conductivity is improved by doping. The polycrystalline silicon film 65 becomes the rotor 51 and the stator electrodes 57 and 58. After the polycrystalline silicon film 65 is formed and before the front surface side dry etching is performed, the polycrystalline silicon film formed on the back surface side is removed by wet etching using the mask material as a mask, and then the rotor 51, the opening 52, 53 and the stator electrodes 57 and 58 are patterned. In this patterning, a high resolution of 1 to 2 μm is required between the rotor electrode and the stator electrode. However, since the surface of the polycrystalline silicon film 65 is almost flat, it is relatively easy to obtain a high resolution. Resolution can be obtained.
[0030]
Thereafter, as shown in FIG. 4 (e), the mask is patterned so that only the periphery of the portion serving as the rotation axis at the center of the rotor is exposed, and the silicon oxide thin film 64 is partially wet etched in hydrofluoric acid. To do. Since this etching proceeds isotropically, an undercut shape is formed.
[0031]
Next, as shown in FIG. 4F, a thermal silicon oxide film 66 is formed on the surface of the polycrystalline silicon film 65 with a thickness of 0.5 μm, for example, and then a polycrystalline silicon 67 is formed with a thickness of, for example, LPCVD. While forming 2 μm, the conductivity is improved by doping. In this case, the thermally oxidized silicon 66 is also a sacrificial layer. Thereafter, the polycrystalline silicon formed on the back surface side is removed, and the polycrystalline silicon 67 on the front surface side is patterned by dry etching so as to leave only the central portion of the rotor. The polycrystalline silicon 67 left in this step becomes the bearing 54.
[0032]
Thereafter, as shown in FIG. 4 (g), the silicon oxide portion that becomes a sacrificial layer in hydrofluoric acid is etched, and between the bearing 54 and the rotor 51 and between the rotor 51 and the single crystal silicon substrate 59. The silicon oxide layers 64 and 66 are removed, and the electrostatic diaphragm structure in which the rotor 51 can rotate with respect to the bearing 54 is completed. Note that, since the polycrystalline silicon film 65 completely covers the periphery of the silicon oxide thin film 64 at the rotor central axis and the lower portions of the stator electrodes 57 and 58 patterned in FIG. 4C, even after the sacrificial layer etching process. The bearing 54 and the stator electrodes 57 and 58 can be kept fixed with respect to the single crystal silicon substrate 59.
[0033]
The electrostatic aperture structure formed as described above is good because the gap between the bearing 54 and the rotor 51 is realized by a thermally oxidized silicon film 66 having a minute thickness of about 0.5 μm serving as a sacrificial layer. Controllability and reproducibility can be obtained.
[0034]
Next, the operation of the electrostatic diaphragm 7 will be described with reference to FIGS. The rotor electrodes 55 and 56 and the stator electrodes 57 and 58 described with reference to FIG. 3 constitute a pair of electrostatic actuators. FIG. 5A shows a state in which the stator electrode 57 and the rotor electrode 55 are in a position facing each other, and this state is realized by applying a voltage V between the electrodes via the switch 69. That is, since the rotor 51 is electrically connected to the GND electrode 63, a voltage of about 15 to 90 V is applied between the stator electrode 57 and the GND electrode 63, for example, so that the rotor 51 is connected between the stator electrode 57 and the rotor electrode 55. The electrostatic attractive force acts on the rotor 51, and the rotor 51 rotates and stops to a position where both faces each other as shown in FIG. Since such electrostatic attraction is inversely proportional to the square of the distance between the two electrodes, the distance between the two is preferably about 1 to 2 μm. This dimensional accuracy is realized by the surface micromachining described in FIG. The
[0035]
By the way, in the state shown in FIG. 5A, the opening 52 formed in the rotor 51 and the through hole 60 formed in the substrate 59 face each other so that their centers coincide with each other. As described above, the positioning is performed by the action of the electrostatic actuator, so that no positioning sensor is required.
[0036]
When the switch 69 is switched from the state shown in FIG. 5A and a voltage V of about 15 to 90 V is applied between the stator electrode 58 and the GND electrode 63, an electrostatic charge is generated between the stator electrode 58 and the rotor electrode 56. The attractive force acts, and thereby the rotor 51 rotates in the clockwise direction, and the rotor 51 is finally positioned so that the stator electrode 58 and the rotor electrode 56 face each other as in the case of FIG. Thus, the state as shown in FIG. 5B is realized. This state is realized without using a positioning sensor because each part is designed so that the center of the opening 53 formed in the rotor 51 and the through hole 60 formed in the substrate 59 coincide with each other. The
[0037]
Since the electrostatic diaphragm 7 described above can be produced in large numbers on a single (100) single crystal silicon substrate (wafer) by a batch process, the size of each electrostatic diaphragm 7 can be reduced within 1 mm square and can be made inexpensive. . In this way, a large number of electrostatic diaphragms 7 formed on the wafer are cut and separated into individual substrates, and the separated electrostatic diaphragm 7 is penetrated by using the back surface of the substrate 59 as an adhesive surface. In FIG. 1, the hole 60 is bonded to the glass prism 21 so as to coincide with the central beam of the diverging light beam emitted from the semiconductor laser 6.
[0038]
Here, even if the thickness of the substrate 59 is 0.5 mm, for example, the electrostatic diaphragm 7 can have an overall thickness of less than 0.6 mm, so that the gap between the semiconductor laser 6 and the glass prism 21 is small. Even if it is very small, it can be easily mounted on the glass prism 21. Furthermore, if necessary, the overall thickness can be reduced by using a thinner substrate.
[0039]
  The electrostatic diaphragm 7 mounted on the glass prism 21 connects the GND electrode 63 and the two stator electrodes 57 and 58 to the corresponding lead terminals 11 via connection lines (not shown). thisReference exampleThen, the GND electrode 63 is commonly connected to a predetermined lead terminal 11 in which the anode of the semiconductor laser 6 and the cathode of each light receiving region formed on the semiconductor substrate 9 are connected. In this way, the mounting man-hour can be minimized.
[0040]
When the electrostatic diaphragm 7 is mounted as described above, the electrostatic diaphragm 7 is driven according to the type of the optical recording medium 3, that is, the recording density, so that the corresponding opening 52 or 53 is centered on the semiconductor laser 6. Can be positioned at a position that coincides with the central ray of the diverging light beam emitted from the light beam, and thereby the outer diameter of the light beam incident on the glass prism 21, and thus the outer diameter of the light beam incident on the objective lens 2, that is, the objective lens 2 Can be increased for an optical recording medium recorded with high density, and can be decreased for an optical recording medium recorded with low density.
[0041]
  thisReference exampleAccording to the present invention, since the electrostatic diaphragm 7 formed by silicon surface micromachining is mounted on the integrated optical unit 1, the unit 1 is not increased in size and the desired optical characteristics are affected. Instead, the beam diameter of the light beam emitted from the unit 1 can be controlled. Therefore, by using such an integrated optical unit 1, it is possible to realize an optical pickup device that is small and excellent in optical characteristics, and thereby records and reproduces information with respect to a plurality of types of optical recording media having different recording densities. Is possible.
[0042]
The electrostatic diaphragm 7 shown in FIG. 1 is not limited to the one shown in FIG. 3, and for example, the one shown in the plan view in FIGS. 6A to 6D can be used. The electrostatic diaphragm 7 is different from that shown in FIG. 3 in the configuration of the stator electrode and the rotor electrode. That is, in this example, a total of eight rotor electrodes 55 a to 55 h are arranged on the circumference of the rotor 51 at equal intervals of a central angle of 45 °, and two of the rotor electrodes 55 a and 55 b are arranged from the center of the rotor 51. It is provided so as to be positioned in the same direction as the openings 52 and 53 when viewed. A total of six stator electrodes 57a to 57f are provided at equal intervals of a central angle of 60 ° so as to face the peripheral surface of the rotor 51. The electrostatic diaphragm 7 having such a configuration is operated as described below as a stator 6-pole-rotor 8-pole electrostatic motor.
[0043]
FIG. 6A shows a state in which the stator electrode and the rotor electrode are not completely opposed to each other. In this state, between the GND electrode 63 and the stator electrodes 57b and 57e facing each other, For example, a voltage of 15 to 90 V is applied, respectively, and the rotor electrodes 55c and 55g closest to both the electrodes 57b and 57e are drawn together to obtain the state shown in FIG. Next, the voltage application is switched to the stator electrodes 57a and 57d, and the stator electrode 57a and the rotor electrode 55b and the stator electrode 57d and the rotor electrode 55f are opposed to each other as shown in FIG. The opening 53 is positioned at a position facing the through hole 60.
[0044]
Also, from the state shown in FIG. 6A, first, a voltage is applied to the stator electrodes 57c and 57f, and then a voltage is applied to the stator electrodes 57a and 57d, as shown in FIG. The stator electrode 57a and the rotor electrode 55a, and the stator electrode 57d and the rotor electrode 55e are made to face each other, thereby positioning the opening 52 at a position facing the through hole 60.
[0045]
As described above, the electrostatic diaphragm 7 shown in FIG. 6 adopts a so-called three-phase driving method in which six stator electrodes 57a to 57f are sequentially applied with voltages as two pairs of two facing each other. Therefore, in the simplest configuration, as shown in principle in FIG. 7A, in addition to the lead terminal 11 to which the GND electrode 63 is connected, the pair of stator electrodes 57a, 57d; 57b, 57e; 57c, 57f Three lead terminals 11 connected to each other are required, and the number of lead terminals 11 is increased by one as compared with the configuration of FIG. 3, but the drive response and positioning accuracy are improved as compared with the case of FIG. To do.
[0046]
Further, as shown in FIG. 7B, if an electrostatic diaphragm driving circuit 70 for generating a control pulse from a direction control signal and a pulse input is provided inside the package, the lead terminal 11 to which the GND electrode 63 is connected can be provided. Except for this, it is possible to use two lead terminals 11 to the outside. The electrostatic diaphragm driving circuit 70 can be formed on the same substrate because the electrostatic diaphragm 7 is formed on the silicon substrate. In this case, the process for forming the drive circuit is performed before the electrostatic diaphragm structure is formed, but the subsequent processes are not affected. Therefore, even when circuit formation is included, the advantages of cost reduction by the batch process and miniaturization by micromachining are maintained.
[0047]
The electrostatic diaphragm 7 shown in FIG. 1 can have various configurations other than the configurations shown in FIGS. 3 and 6. For example, the electrode arrangement may be other configurations such as stator 12 pole-rotor 16 pole. Also, the material of the electrostatic diaphragm and the process are not limited to the above-described examples. For example, in order to improve the light shielding property of polycrystalline silicon which is a rotor material, a nickel thin film is finally formed by electroless plating. It is also possible to add a process such as forming on the rotor. Alternatively, the electrostatic diaphragm can be formed by a process in which a material such as nickel that can be formed by plating is used as a structural material and polycrystalline silicon is used as a sacrificial layer.
[0048]
  As a reference exampleThe electrostatic aperture 7 can be formed directly by a process using a transparent substrate such as glass instead of a silicon substrate, using nickel or the like as a structural material, and using a photoresist as a sacrificial layer. In this case, it is possible to reduce the step of processing the through hole in the substrate.
[0049]
  8 and 9 show the present invention.oneIt is the schematic sectional drawing and schematic partial perspective view which show embodiment. In this embodiment, a light beam from the integrated optical unit 101 is irradiated onto the read-only optical recording medium 103 via the objective lens 2, and the return light is incident on the integrated optical unit 101 via the objective lens 2. , The diameter of the light beam incident on the objective lens 2 from the integrated optical unit 101, that is, the numerical aperture of the objective lens 2,Reference example aboveIn the same way as in the case of the above, according to the type of the optical recording medium 103, that is, the recording density, it is large in the case of the optical recording medium 103 recorded with high density and small in the case of the optical recording medium 103 recorded with low density. It is made to control like this.
[0050]
The integrated optical unit 101 is housed in a package 105 and is provided with a semiconductor laser 106, an electrostatic aperture 107 and a semiconductor substrate 109. The package 105 includes a stem 112 made of ceramic or the like provided with a plurality of lead terminals 111 and a hologram element 113.
[0051]
The semiconductor substrate 109 is fixed to the stem 112. A recess 109a is formed in the semiconductor substrate 109 by anisotropic etching, a semiconductor laser 106 is mounted on the recess 109a, and a diverging light beam emitted from the semiconductor laser 106 is formed by anisotropic etching. The light is reflected by the etched mirror 71 and emitted from the hologram element 113 through the electrostatic aperture 107.
[0052]
The semiconductor substrate 109 includes light receiving portions 116 and 117 for detecting information signals and focus error signals from the return light from the optical recording medium 103, and a light receiving region 118a for detecting tracking error signals from the return light. , 118b; 119a, 119b. Each of the light receiving portions 116 and 117 includes light receiving regions 116a, 116b, and 116c; 117a, 117b, and 117c that are divided into three by dividing lines in a direction parallel to the track of the optical recording medium 103. The cathode of each light receiving region formed on the semiconductor substrate 109 is connected to a common predetermined lead terminal 111 together with the anode of the semiconductor laser 106.
[0053]
The electrostatic diaphragm 107 is formed on the semiconductor substrate 109 together with each of the light receiving regions described above, and is a diameter of a diverging light beam emitted from the semiconductor laser 106, reflected by the etching mirror 71 and incident on the hologram element 113, that is, the objective lens 2. Is controlled in accordance with the recording density of the optical recording medium 103. The configuration of the electrostatic diaphragm 107 and the formation process thereof will be described later.
[0054]
The hologram element 113 is configured by forming a diffraction grating 113a on one surface of a glass substrate and forming a hologram pattern 113b having a slight curvature on the other surface so that the diffraction grating 113a is located in the package 105. Attach to stem 112.
[0055]
In this embodiment, after the light beam diverging from the semiconductor laser 106 is reflected by the etching mirror 71, the beam diameter is controlled by the electrostatic diaphragm 107 according to the type of the optical recording medium 103, and the diffraction grating 113a. Thus, a reproduction light beam of 0th order light and two tracking light beams of ± 1st order diffracted light are obtained. These three light beams are incident on the hologram pattern 113b, and each zero-order light is irradiated onto the optical recording medium 103 in a spot shape through the objective lens 2 in a predetermined positional relationship.
[0056]
Further, the return light of each light beam reflected by the optical recording medium 103 is incident on the hologram pattern 113b of the hologram element 113 through the objective lens 2, and here is ± first-order diffracted light that has moved image points in opposite directions. To separate. The + 1st order diffracted light of the return light of the reproduction light beam diffracted by the hologram pattern 113b is received by the light receiving unit 116, for example, and the −1st order diffracted light is received by the light receiving unit 117. The ± 1st order diffracted light of the return light of one tracking light beam is received by the light receiving regions 118a and 118b, respectively, and the ± 1st order diffracted light of the other tracking light beam is received by the light receiving regions 119a and 119b. Each receives light.
[0057]
In this way, the respective outputs of the light receiving regions 116a to 116c of the light receiving unit 116 are set to I_116a~ I_116c, The respective outputs of the light receiving regions 117a to 117c of the light receiving unit 117 are expressed as I_117a~ I_117cWhen the reproduction signal RF is
RF = (I_116a+ I_116b+ I_116c) + (I_117a+ I_117b+ I_117c)
The focus error signal FES is obtained using the beam size method.
FES = (I_116a+ I_117b+ I_116c)-(I_117a+ I_116b+ I_117c)
By Further, the tracking error signal TES outputs the respective outputs of the light receiving regions 118a and 118b; 119a and 119b as I_118a, I_118bI_119a, I_119bWhen using the 3-beam method,
TES = (I_118a+ I_118b)-(I_119a+ I_119b)
By
[0058]
Next, the configuration of the electrostatic diaphragm 107 shown in FIGS. 8 and 9 and the formation process thereof will be described.
FIGS. 10A and 10B are a plan view and a cross-sectional view showing a configuration of an example of the electrostatic diaphragm 107. FIG. The electrostatic diaphragm 107 has the same basic configuration as that described in FIG. 3 except that the etching mirror 71 is formed on the silicon substrate 109. Accordingly, components having the same functions as those shown in FIG. 3 are denoted by the same reference numerals, and detailed description thereof is omitted. The main points of the creation process will be described below.
[0059]
First, an etching mirror 71 is formed using a silicon single crystal substrate. At this time, since the mirror 71 needs to have an inclination of 45 ° with respect to the substrate surface, the surface is not the normal (100) surface, but the (100) surface off by 9 ° in the <110> direction is the surface. The etching mirror 71 is formed by anisotropic etching using the silicon substrate 109 having the same.
[0060]
Subsequently, an electrostatic diaphragm structure is formed. The manufacturing process is basically the same as that described with reference to FIG. 4, but the thin film formed by LPCVD transfers the surface shape as it is, so that the rotor 51 having a flat structure is formed above the etching mirror 71 having an inclination of 45 °. Is difficult to form. Therefore, in this example, an electrostatic diaphragm structure is formed on the upper surface of the flat portion of the substrate surface, and finally the rotor 51 is rotated so that the opening 52 or 53 is positioned at a predetermined position, that is, directly above the etching mirror 71. So that Specifically, an electrostatic diaphragm structure is created with the arrangement shown in FIG. This creation process is the same as that shown in FIG.
[0061]
After the electrostatic diaphragm structure is created, the rotor 51 is rotated about 180 degrees with a prober or the like to obtain the state shown in FIG. In this state, by applying a voltage between the GND electrode 63 and the stator electrode 57, the opening 53 is positioned immediately above the etching mirror 71, and a voltage is applied between the GND electrode 63 and the stator electrode 58. By doing so, the opening 52 is positioned immediately above the etching mirror 71. Also in the electrostatic diaphragm 107, the rotor 51 is positioned at a position where the stator electrode and the rotor electrode are opposed to each other, whereby the openings 52 and 53 are selectively positioned directly above the etching mirror 71. There is no need to use the sensor.
[0062]
When the electrostatic diaphragm 107 is mounted in the integrated optical unit 101 as described above, the corresponding opening 52 or 53 is formed by driving the electrostatic diaphragm 107 according to the type of the optical recording medium 103, that is, the recording density. The center of the light beam emitted from the semiconductor laser 106 can be positioned so as to coincide with the central beam of the diverging light beam, thereby increasing the outer diameter of the light beam incident on the objective lens 2, that is, the numerical aperture of the objective lens 2. It can be large for an optical recording medium recorded with a density, and small for an optical recording medium recorded with a low density.
[0063]
In addition, the electrostatic diaphragm 107 is monolithically formed by a batch process on the silicon substrate 109 that is one of the components of the integrated optical unit 101, and thus has features of small size, low cost, and high accuracy. . Further, the number of lead terminals 111 taken out from the package 105 is also reduced to a minimum of two by connecting the GND electrode 63 in common to the lead terminal 111 connecting the anode of the semiconductor laser 106 and the cathode of each light receiving region. Therefore, the influence on the unit size and the mounting process can be minimized.
[0064]
Therefore, also in this embodiment, the beam diameter of the light beam emitted from the unit 101 can be controlled without increasing the size of the unit 101 and without affecting the desired optical characteristics. By using such an integrated optical unit 101, it is possible to realize a small optical pickup device that can reproduce information on a plurality of types of optical recording media having different recording densities and excellent in optical characteristics.
[0065]
The electrostatic diaphragm 107 shown in FIGS. 8 and 9 is not limited to the one shown in FIG. 10, but may be configured as shown in plan views in FIGS. 12 (a) and 12 (b), for example. The electrostatic diaphragm 107 has basically the same configuration as that shown in FIG. 10, but the arrangement of the rotor electrode and the stator electrode is different. That is, in this example, a total of eleven rotor electrodes 55 are arranged on the circumference of the rotor 51 at equal intervals of a central angle of 22.5 °, and two of them are the openings 52 as viewed from the center of the rotor 51. , 53 to be located in the same direction. A total of seven stator electrodes 57 a to 57 g are provided at equal intervals of a central angle of 30 ° so as to face the peripheral surface of the rotor 51. The electrostatic diaphragm 107 having such a configuration is a stator 12-pole-rotor 16-pole electrostatic motor if the rotor electrode and the stator electrode are all around the circumference, but there is a portion that is not flat on the substrate. The configuration is as shown in the figure. Hereinafter, the operation of the electrostatic diaphragm 107 will be described.
[0066]
FIG. 12A shows a state in which the stator electrode 57d is completely opposed to the rotor electrode. In this state, a voltage of, for example, 15 to 90 V is applied to the stator electrodes 57b and 57e with respect to the GND electrode. Then, the rotor electrodes closest to both the electrodes are drawn together to rotate the rotor 51 by 7.5 ° counterclockwise. Further, a voltage is applied to the stator electrodes 57c and 57f, and the rotor 51 is further rotated by 7.5 ° counterclockwise. By repeating this operation (21 times), the rotor 51 is rotated counterclockwise by 157.5 ° from the state shown in FIG. 12A, and the opening 53 is etched as shown in FIG. 12B. Position directly above the mirror 71. Also, the order of voltage application to the stator electrodes is reversed, and the rotor 51 is rotated clockwise by a predetermined angle, whereby the opening 52 is positioned directly above the etching mirror 71.
[0067]
As described above, the electrostatic diaphragm 107 shown in FIG. 12 adopts a so-called three-phase driving method in which voltages are sequentially applied with three pairs of stator electrodes. Therefore, in the simplest configuration, as shown in FIG. 7A, in addition to the lead terminal 11 to which the GND electrode 63 is connected, three lead terminals 11 to which the pair of stator electrodes are respectively connected are required. However, since the operation of rotating the rotor 51 by about 180 ° is performed by electrically driving the rotor 51, this operation can be automated and the work load can be reduced.
[0068]
Similarly to the case shown in FIG. 7B, if an electrostatic diaphragm driving circuit for generating a control pulse from a direction control signal and a pulse input is provided in the package, two lead wires to the outside are provided. It is also possible. This electrostatic diaphragm drive circuit can be formed on the same substrate because the electrostatic diaphragm 107 is formed on the silicon substrate. In this case, the circuit is manufactured before the electrostatic diaphragm structure is formed. However, the subsequent processes are not affected. Therefore, even when circuit fabrication is included, the advantages of cost reduction by batch process and miniaturization by micromachining are maintained.
[0069]
  The electrostatic diaphragm 107 shown in FIGS. 8 and 9 is not limited to the configuration shown in FIGS. 10 and 12, but in terms of the number and arrangement of electrodes, constituent materials and processes,Reference example aboveVarious modifications are possible in the same manner as described above. 10 and 12, the electrostatic diaphragm 107 is formed so as to avoid the concave portion 109a on the substrate surface, but after flattening the substrate surface with a material such as spin-on-glass, for example,Reference example aboveIt is also possible to create the electrostatic diaphragm structure having the structure described in the above, and finally, remove the material used for planarization simultaneously with the sacrifice layer etching to form the electrostatic diaphragm 107.
[0070]
  BookIn the embodiment, the outer diameter of the light beam incident on the objective lens, that is, the numerical aperture of the objective lens is increased with respect to the optical recording medium recorded with high density by using the electrostatic diaphragm. Although the recording medium is reduced in size, the same operation can be performed using an electromagnetic diaphragm instead of the electrostatic diaphragm.
[0071]
Hereinafter, the configuration of the electromagnetic diaphragm and the formation process thereof will be described.
FIG. 13 is a plan view showing a configuration of an example of an electromagnetic diaphragm. The electromagnetic diaphragm 130 is a variable reactance type stepping motor, and a Ni-Fe rotor 133 having a thickness of 40 μm and an outer diameter of 260 μm, for example, rotatably supported on a support shaft 132 formed on the semiconductor substrate 131. Have. The rotor 133 has, for example, a circular opening 134 having a diameter of 45 μm, for example, for controlling the diameter of a light beam from a semiconductor laser (not shown) on the circumference having a radius of 100 μm, for example, 24 ° apart from the center angle. A circular opening 135 having a diameter of 30 μm is formed, and six protrusions 133a to 133f are provided in a peripheral portion almost opposite to the side on which these openings are formed with a central angle of 36 ° apart.
[0072]
In addition, the semiconductor substrate 131 has three U-shaped yoke patterns 136a to 136c outside the rotor 133, and coil patterns 137a to 137c formed so as to wind each yoke pattern. Form. Each yoke pattern has a U-shaped end portion that becomes a magnetic pole portion spaced apart by 36 ° at the central angle to face the rotor 133, and the end portions of adjacent yoke patterns are spaced apart by 24 ° at the central angle. Form. Also, the semiconductor substrate 131 passes a light beam from a semiconductor laser (not shown) that has passed through the opening 134 or 135 at a position that is 100 μm in radius from the rotation center on the lower side of the rotor 133. For example, the square through hole 141 is formed so that the opening area thereof becomes smaller toward the rotor 133. The through hole 141 has an opening 134, formed in the rotor 133 with the center thereof in the state shown in FIG. 13, that is, in a state where the protrusions 133c, 133d of the rotor 133 and both ends of the yoke pattern 136b face each other. It is formed so as to be located in the middle of 135, that is, at a center angle of 12 ° from the center of each opening.
[0073]
The state shown in FIG. 13 shows a state in which a current is passed through the coil pattern 137b. In this state, magnetic poles are formed at both ends of the yoke pattern 136b, and the protrusions 133c and 133d of the rotor 133 are magnetically formed at both ends. A closed magnetic path that passes through the yoke pattern 136b and the protrusions 133c and 133d is formed so as to be attracted to and opposed to each other. From this state, for example, when positioning the opening 134 of the rotor 133 in the optical path where the through hole 141 is located, the energization to the coil pattern is switched from the coil pattern 137b to the coil pattern 137a. In this way, magnetic poles are formed at both ends of the yoke pattern 136a, whereby the protrusions 133a and 133b of the rotor 133 that are spaced apart from each other by 12 ° at the central angle are magnetically applied to the adjacent magnetic poles. Sucked. As a result, the rotor 133 rotates to the right by 12 °, a closed magnetic path passing through the yoke pattern 136a and the protrusions 133a and 133b is formed, and the opening 134 of the rotor 133 is positioned in the optical path.
[0074]
Further, when the opening 135 is positioned in the optical path from the state where the opening 134 is positioned in the optical path, the energization to the coil pattern is sequentially switched from the coil pattern 137a to the coil pattern 137b and the coil pattern 137c. In this case, first, the rotor 133 is rotated 12 ° to the left by switching the energization to the coil pattern 137b, and then the rotor 133 is rotated 12 ° to the left by switching the energization to the coil pattern 137c. As a result, the magnetic poles at both ends of the yoke pattern 136c and the protrusions 133e and 133f of the rotor 133 face each other to form a closed magnetic path. Are positioned in the optical path. Further, when the energization is switched to the coil pattern 137b from this state, the state shown in FIG. 13 is obtained. In addition, such an energization method can be performed by the structure similar to the structure shown in FIG.
[0075]
  Next, as shown in FIG.electromagneticA method for manufacturing the diaphragm 130 will be described with reference to FIGS. 14 and 15.
  First, a silicon nitride film 145 serving as an insulating layer is formed on a semiconductor substrate (for example, a single crystal silicon (100) substrate) 131 for forming the stator 138 by, for example, PECVD (Plasma Enhanced Chemical Vapor Deposition) to 0.6 μm. Grow about thick. In this case, since the film is formed on both sides of the substrate, the film on the substrate surface is used as an insulating layer, and the film on the back surface is used as a mask for forming the through hole 141 for the optical path in the substrate. That is, a photoresist is coated on the back side, and, for example, a square opening of about 3 to 5 mm square is patterned, and the silicon nitride film 145 is etched using this as a mask. At this time, patterning is performed so that each side of the square coincides with the direction of the (111) plane of silicon. Next, using this silicon nitride film 145 as a mask, the substrate is etched through with potassium hydroxide or the like. In this way, the etching is stopped so that the substrate (111) surface is exposed, and the etching stops when the back surface of the silicon nitride film 145 on the front surface side is exposed (see FIG. 14A).
[0076]
Next, an electroplating seed layer 146 made of Cr (0.05 μm) / Cu (0.2 μm) / Cr (0.07 μm) is formed on the substrate surface side by, for example, vapor deposition. Thereafter, polyimide 147 is coated to a thickness of about 40 μm. After this coating, the silicon nitride film 145 remaining on the upper portion of the through hole 141 is etched from the back side (see FIG. 14B).
[0077]
Subsequently, the polyimide 147 is patterned by dry etching using an aluminum mask, and a magnetic material 148 such as Ni—Fe is plated by electrolytic plating on the portion removed by this patterning. This magnetic material 148 becomes the lower layer portion of the yoke pattern and the lowermost layer portion of the support shaft 132 (see FIG. 15A).
[0078]
Next, polyimide 147 is coated for insulation between the yoke pattern and the coil pattern and cured at about 350 ° C. To form the coil pattern, as in the case of forming the yoke pattern, first, a plating seed layer is formed, and a photoresist of about 8 μm thickness is patterned thereon to form a plating mold, and finally Cu is electrolyzed. Plating. In the final stage, in order to connect the gold wire to the coil by wire bonding, the surface of the coil and the bonding pad are plated with gold having a thickness of about 0.5 μm. After the plating is completed, the photoresist is removed with ascent and the seed layer is removed by wet etching to form a coil pattern (see FIG. 15B).
[0079]
Thereafter, in order to insulate the coil pattern again and flatten the surface, a polyimide having a thickness of about 10 μm is coated and cured at a high temperature. Next, through holes in the upper and lower layers of the yoke pattern and a part of the support shaft are patterned by dry etching, a lower layer part of the yoke pattern and a part of the lowermost layer part of the support shaft 132 are exposed. At this time, since the exposed surface is oxidized, the oxide film is removed with hydrofluoric acid or the like, and then Ni—Fe is electroplated using the yoke pattern as a seed layer (see FIG. 15C).
[0080]
Next, after patterning the nickel seed layer and forming a Cr dummy seed layer, the upper layer portion of the yoke pattern, its magnetic pole portion, and the support shaft 132 are formed (see FIG. 15D). Since a high aspect ratio is required for forming the structure in this step, 40 μm thick photosensitive polyimide is patterned to form a plating mold, and after removing the Cr seed layer, electrolytic plating is performed.
[0081]
Finally, the mold photosensitive polyimide and the remaining Cr seed layer are removed, and the photosensitive polyimide or photoresist around the support shaft is completely removed to the substrate surface to obtain the stator 138. At this point, the through hole 141 provided in advance in the substrate is exposed on the surface side. The bonding pad is formed by removing polyimide by dry etching similar to the formation of the through hole.
[0082]
Separately from the manufacturing process of the stator 138 described above, a Ni—Fe rotor 133 having a thickness of 40 μm is formed by a process using a photosensitive polyimide as a mold in the same manner as the above-described stator manufacturing method, and this is formed on the support shaft 132. To obtain a variable reactance type stepping motor (see FIG. 15E). In FIGS. 15A to 15E, illustration of the silicon nitride film 145 first formed on both surfaces of the semiconductor substrate 131 in FIG. 14A is omitted.
[0083]
The manufacturing process of the electromagnetic diaphragm 130 described above is basically that a mold having the shape of a structure is made of resin (polyimide or photoresist), and this is electroplated to form a metal structure. Although unnecessary portions of the mold are removed, the details can be slightly changed. For example, mold patterning methods such as patterning photosensitive polyimide or photoresist by photolithography, patterning polyimide by dry etching, etc. should be used depending on specifications such as mold thickness and minimum patterning dimensions. Can do. Further, regarding the plating, it is possible to create a structure not only by electrolytic plating but also by electroless plating. In this case, activation of the surface to be plated is required, but there is an advantage that it is not necessary to form a seed layer before plating.
[0084]
Further, in the manufacturing process of the electromagnetic diaphragm 130 described above, the rotor 133 is separately prepared and assembled last, but the final plating process (formation of the upper layer portion of the yoke pattern, its magnetic pole portion, and the rotor support shaft) is performed. In this case, the rotor 133 can be formed at the same time. In this case, in order to reduce the distance between the rotor 133 and the stator 138 and the distance between the rotor 133 and the support shaft 132, high aspect ratio processing is required at the time of patterning the mold. Patterning with a minimum line width of 2 μm is also possible using a photoresist, and if this is used, a monolithic motor can be manufactured.
[0085]
The electromagnetic diaphragm 130 having the above configuration can be applied to the integrated optical unit 1 having the configuration shown in FIGS. 1 and 2 in place of the electrostatic diaphragm 7, and the integrated configuration having the structures shown in FIGS. 8 and 9. The mold optical unit 101 can also be applied in place of the electrostatic aperture 107. For example, in the integrated optical unit 101 having the configuration shown in FIGS. 8 and 9, when the electrostatic diaphragm 107 is replaced with the electromagnetic diaphragm 130, the wavelength of the emitted light of the semiconductor laser 106 is 780 μm, and the grating pitch of the hologram pattern 113b is When the distance between the top surface of the semiconductor substrate 109 and the hologram pattern 113b is 4 mm, the spot of the return light from the optical recording medium 103 incident on the light receiving unit 116 and the light receiving unit 117 is the emission center of the semiconductor laser 106. About 1 mm away. Here, since the rotor 133 of the electromagnetic diaphragm 130 has an outer diameter of 260 μm, the rotor 133 does not block the return light incident on the light receiving unit 116 and the light receiving unit 117, respectively. Therefore, in FIGS. 8 and 9, the electrostatic diaphragm 107 can be replaced with the electromagnetic diaphragm 130 without any problem.
[0086]
FIG. 16 is a plan view schematically showing the configuration of another example of the electromagnetic diaphragm. The electromagnetic diaphragm 150 includes a rotor 153 formed on the semiconductor substrate 151 and rotatably supported on a support shaft 152 having a diameter of 20 μm, for example, and protruding from a part of a disk having a diameter of 190 μm, for example. The rotor 153 has, for example, a diameter for controlling the diameter of a light beam from a semiconductor laser (not shown) at a protruding portion thereof, for example, 32.5 ° apart from the circumference of a radius of 90 μm, for example, at a central angle. A circular opening 154 having a diameter of 45 μm and a circular opening 155 having a diameter of 30 μm are formed, and on the side substantially opposite to the side where these openings are formed, for example, a fan-shaped area having a central angle of 16 ° (a hatched area) ), Magnets 156a and 156b magnetized in the thickness direction are formed almost symmetrically. Note that the magnets 156a and 156b are magnetized in the direction perpendicular to the paper surface in FIG. 16, for example, such that the front side in the vertical direction of the paper surface is the N pole and the opposite side (the side in contact with the rotor 153) is the S pole.
[0087]
Further, the semiconductor substrate 151 is provided with a semiconductor laser (not shown) that has passed through the opening 154 or 155 at a position spaced 90 μm in radius from the rotation center of the rotor 153, as in the case of the electromagnetic diaphragm shown in FIG. For example, a square-shaped through hole 161 for allowing the light beam to pass therethrough is formed so that the opening area thereof becomes smaller toward the rotor 153. The through hole 161 is formed so that the center thereof is located 22.5 ° away from the center of the opening 154 formed in the rotor 153 and 10 ° away from the center of the opening 155 in the state shown in FIG. .
[0088]
Further, on the semiconductor substrate 151, a stator 158 having two coil patterns 157a and 157b formed substantially axially symmetrical so as to face the magnets 156a and 156b, respectively, is formed below the rotor 153. Each coil pattern is formed in a fan shape in a region having a central angle of 90 ° so that current flows in the same direction in the region having a central angle of approximately 30 °. The magnets 156a and 156b of the rotor 153 and the coil patterns 157a and 157b of the stator 158 corresponding to the magnets 156a and 157a in the state shown in FIG. Similarly, the magnets 156b and the coil pattern 157b are formed so as to be in a positional relationship in which the edges of the magnets 156b and the coil patterns 157b substantially coincide with each other.
[0089]
Further, in order to selectively position the centers of the openings 154 and 155 at the center of the through hole 161, as shown in a partial plan view in FIG. 17, for example, in the vicinity of the innermost periphery of the rotor 153, a radius of 15 μm, for example. Two cylindrical stoppers 158a and 158b each having a diameter of, for example, 8 μm are provided 180 ° apart from each other on the circumference, and a flange 159 having a diameter of, for example, 40 μm is provided on the support shaft 152 to prevent the rotor 153 from coming off. The flange 159 is formed with notches 160a and 160b that engage with the stoppers 158a and 158b, respectively. The notches 160a and 160b are 60 [deg.] At the central angle and are formed to be axially symmetric. When the rotor 153 is in the state shown in FIG. 16, the stoppers 158a and 158b and the notches 160a and 160b are shown in FIG. It should be in the positional relationship shown in.
[0090]
Thus, when the rotor 153 is rotated 22.5 ° rightward from the state shown in FIGS. 16 and 17, the stoppers 158a and 158b are brought into contact with one edge of the corresponding notches 160a and 160b. When the center of the opening 154 coincides with the center of the through hole 161 and the rotor 153 is rotated 10 ° to the left from the state shown in FIG. 17, the stoppers 158a and 158b have the corresponding notches 160a and 160b. The center of the opening 155 coincides with the center of the through hole 161 in contact with the other edge.
[0091]
In the electromagnetic diaphragm 150, when the coil patterns 157a and 157b are energized as shown by arrows, for example, from the state shown in FIG. 16, the rotor 153 rotates 10 degrees to the left, for example, due to electromagnetic action with the magnets 156a and 156b. Thus, the center of the opening 155 is positioned at the center of the through hole 161. Further, when the energization direction to the coil patterns 157a and 157b is switched from this state to the reverse direction, the rotor 153 rotates 32.5 ° rightward, and the center of the opening 154 is positioned at the center of the through hole 161. The
[0092]
Next, a method for manufacturing the electrostatic diaphragm 150 shown in FIG. 16 will be described with reference to FIG.
First, a silicon nitride film 165 serving as an insulating layer is grown on a semiconductor substrate (for example, a single crystal silicon (100) substrate) 151 by, for example, PECVD (Plasma Enhanced Chemical Vapor Deposition) to a thickness of about 0.6 μm. In this case, since films are formed on both sides of the substrate, the film on the surface of the substrate is used as an insulating layer, and the film on the back surface is used as a mask for forming the through hole 161 for the optical path in the substrate. That is, a photoresist is coated on the back side, and a square opening of about 3 to 5 mm square, for example, is patterned, and the silicon nitride film 165 is etched using this as a mask. At this time, patterning is performed so that each side of the square coincides with the direction of the (111) plane of silicon. Next, using this silicon nitride film 165 as a mask, the substrate is etched through with potassium hydroxide or the like. By doing so, the etching is stopped so that the substrate (111) surface is exposed, and the etching stops when the back surface of the silicon nitride film 165 on the front surface side is exposed (see FIG. 18A).
[0093]
Next, an electroplating seed layer 166 composed of Cr (0.05 μm) / Cu (0.2 μm) / Cr (0.07 μm) is formed on the substrate surface by, for example, vapor deposition. Thereafter, polyimide 167 is coated to a thickness of about 40 μm. After this coating, the silicon nitride film 165 remaining on the upper portion of the through hole 161 is etched from the back side (see FIG. 18B). Subsequently, using an aluminum mask, the polyimide 167 is patterned by dry etching, and a coil pattern located under the rotor 153 and Cu 168 serving as the lowermost layer of the support shaft 152 are formed on the portion removed by the patterning. It is formed by electroplating to the same thickness as polyimide (about 40 μm) (see FIG. 18C).
[0094]
Next, in order to ensure the surface flatness and the space between the rotor 153 and the coil pattern, the photoresist 169 is coated with a thickness of about 5 μm to 10 μm, and only the portion of the support shaft 152 is patterned to form the surface. The support shaft of Cu 168 was used as a seed layer to form a support shaft of Ni by electrolytic plating (see FIG. 18D), and a photoresist 170 serving as a sacrificial layer was coated to a thickness of about 5 μm, and the support shaft was patterned. Subsequently, Ni electrolytic plating is performed. Here, the diameter of the support shaft is made smaller than the diameter of the lower stage so that the vertical positioning when the rotor 153 is formed later can be performed (see FIG. 18E).
[0095]
Further, after an electroplating seed layer 171 composed of Cr (0.05 μm) / Cu (0.2 μm) / Cr (0.07 μm) is formed, for example, by vapor deposition, a photoresist is formed for rotor formation. Coating is performed to a thickness of about 23 μm, and the rotor (including openings 154 and 155) and the support shaft are patterned to form the rotor 153 and the support shaft 152 by electrolytic plating (see FIG. 18F).
[0096]
Thereafter, in order to secure a gap between the rotor 153 and the flange portion of the rotor formed on the upper portion of the support shaft 152, 1 μm thick photoresist 172 is coated, and the stopper forming portion on the rotor 153 and the support shaft 152 are formed. Then, electrolytic Ni plating is performed by patterning the flange connection portion (see FIG. 18G). Further, after forming a seed layer of electrolytic plating composed of Cr (0.05 μm) / Cu (0.2 μm) / Cr (0.07 μm) by, for example, vapor deposition, etc., in order to form a stopper and a flange The photoresist 173 is coated with a thickness of 10 μm to 15 μm and patterned, and thereafter, electrolytic Ni plating is performed to form stoppers 158a and 158b and a flange 159 (see FIG. 18H). What should be noted here is that in the final step, when removing the photoresist 170 serving as the sacrificial layer, the position in the height direction of the rotor 153 decreases by the thickness of the sacrificial layer (5 μm), and FIG. Therefore, the stoppers 158a and 158b and the flange 159 are sufficiently thick with respect to the sacrificial layer (10 μm to About 15 μm). A plan view of the stoppers 158a and 158b and the flange 159 formed by this process is as shown in FIG.
[0097]
Next, in order to pattern the magnet region on the rotor 153, an aluminum thin film serving as a mask is formed and patterned, and using this as a mask, photoresists 172 and 173 formed in the previous two steps (total thickness 11 μm to 16 μm) is patterned by dry etching. Subsequently, after forming a magnet region with CoNiMnP by electrolytic plating, a magnetizing step is performed to form magnets 156a and 156b as shown in FIG. 18 (i), for example.
[0098]
Finally, the photoresist or polyimide is removed, and the seed layer is removed, so that the rotor 153 can be rotated to complete the electromagnetic diaphragm 150 (see FIG. 18J).
[0099]
Since the electromagnetic diaphragm 150 has a structure in which the rotor 153 and the stator 158 are overlapped, there is an advantage that the size can be further reduced.
[0100]
The manufacturing process shown in FIG. 18 is basically similar to the process shown in FIGS. 14 and 15 in that a mold having the shape of a structure is made of resin (polyimide or photoresist), and this is electrolyzed. Plating is performed to form a metal structure, and finally, unnecessary portions of the mold are removed. Details can be changed in the same manner as described above.
[0101]
  In addition, this invention is not limited only to embodiment mentioned above, Many deformation | transformation or a change is possible. For example,EmbodimentThen, the diverging light beam emitted from the integrated optical unit is converged by the objective lens and applied to the optical recording medium, but a reflection mirror is provided between the integrated optical unit and the objective lens, The optical axis may be bent by 90 °. In this way, the optical pickup device can be thinned. Further, the diverging light beam emitted from the integrated optical unit is converted into a parallel light beam by a collimator lens, and then incident on the objective lens directly on the objective lens or by bending the optical axis by 90 ° with a reflection mirror. You can also.
[0102]
In particular, if the integrated optical unit according to the present invention is used for a fixed part in a separation optical system having a fixed part and a movable part as disclosed in, for example, Japanese Patent Laid-Open No. 63-224037, it is movable. Various problems in the case of controlling the diameter of the light beam by providing a diaphragm at the portion can be effectively solved. In other words, when controlling the diameter of the light beam by providing a diaphragm in the movable part, the weight of the movable part increases, tracking sensitivity decreases, and a diaphragm driving cable is required. Changes in the intensity distribution and aberrations of the light beam collected on the recording medium occur due to a decrease in access speed, or a misalignment between the fixed part and the movable part diaphragm, or incident on the diaphragm of the movable part Although the light beam divergence angle is increased and the entire movable part is enlarged, the integrated optical unit according to the present invention is provided in the fixed part, and light is transmitted by the diaphragm in the integrated optical unit. If the beam diameter is controlled, the above problems do not occur.
[0103]
Furthermore, the present invention can be effectively applied to an optical pickup device that records or reproduces information on a card-like optical recording medium.
[0104]
  Appendix
1.Claim 1In the integrated optical unit described,
  An integrated optical unit, wherein the semiconductor laser, the photodetector and the ground electrode of the diaphragm are connected to a common lead terminal.
[0105]
【The invention's effect】
  According to this invention,A semiconductor laser is disposed in a concave portion of a semiconductor substrate having a reflective surface and a concave portion formed by etching so that a diverging light beam from the semiconductor laser is incident on the hologram element through the reflective surface. A diaphragm having an electrostatically or electromagnetically rotatable rotor for controlling the diameter of the light beam incident on the hologram element via the reflecting surface is provided in the vicinity of the reflecting surface, and the hologram is disposed at a position off the diaphragm. A photodetector is provided to receive the return light from the recording medium separated by the element without passing through the diaphragm.Therefore, the problem of dependency on the incident angle when using the liquid crystal filter and the problem of enlargement when using the mechanical variable aperture means are not caused.At the same time, by forming a diaphragm on the semiconductor substrate together with the photodetector, it is possible to achieve small size, low price and high accuracyControl the diameter of the light beam emitted from the semiconductor laser without affecting the desired optical propertiesit canAn integrated optical unit can be obtained.
[0106]
  As a reference example, when a diaphragm is provided on a glass substrate, an optical member mounted on the glass substrate can be used by applying a resist or patterning on the prism.it can.
[Brief description of the drawings]
FIG. 1 is a schematic sectional view showing a reference example of an integrated optical unit developed together with the present invention.
FIG. 2 is also a schematic partial perspective view.
FIG. 3 is a diagram for explaining a configuration of an example of the electrostatic diaphragm shown in FIG. 1;
4 is a diagram for explaining an example of a forming process of the electrostatic diaphragm shown in FIG. 3; FIG.
FIG. 5 is also a diagram for explaining the operation of the electrostatic diaphragm.
6 is a diagram for explaining the configuration and operation of another example of the electrostatic diaphragm shown in FIG. 1; FIG.
7 is a diagram for explaining two driving modes of the electrostatic diaphragm shown in FIG. 6; FIG.
FIG. 8 of the present inventiononeIt is a schematic sectional drawing which shows embodiment.
FIG. 9 is a schematic partial perspective view of the same.
FIG. 10 is a diagram for explaining the configuration of an example of the electrostatic diaphragm shown in FIG.
FIG. 11 is also a diagram for explaining the operation of the electrostatic diaphragm.
12 is a diagram for explaining the configuration and operation of another example of the electrostatic diaphragm shown in FIG. 8; FIG.
FIG. 13 is a schematic plan view showing a configuration of an example of an electromagnetic diaphragm as a diaphragm provided in the integrated optical unit according to the present invention.
FIG. 14 is a view for explaining an example of the electromagnetic diaphragm forming process shown in FIG. 13;
FIG. 15 is also a view for explaining a formation process.
FIG. 16 is a diagrammatic plan view showing the configuration of another example of an electromagnetic diaphragm as a diaphragm provided in the integrated optical unit according to the present invention.
17 is a partial plan view of the electromagnetic diaphragm shown in FIG.
FIG. 18 is also a view for explaining an example of a forming process of the electromagnetic diaphragm shown in FIG. 16;
[Explanation of symbols]
  1 Integrated optical unit
  2 Objective lens
  3 Optical recording media
  5 packages
  6 Semiconductor laser
  7 Electrostatic diaphragm
  8 Beam splitter
  9 Semiconductor substrate
  11 Lead terminal
  12 stem
  13 Hologram element
  13a Hologram pattern
  14 cap
  15, 16a, 16b, 17a, 17b, 17c, 18a, 18b, 18c light receiving area
  16, 17, 18
  21 Glass prism
  22 Uniaxial birefringent crystal prism
  23 Polarizing film
  51 rotor
  52,53 opening
  54 Bearing
  55, 56 Rotor electrode
  57,58 Stator electrode
  59 Silicon substrate
  60 Through hole
  63 GND electrode
  130 Electromagnetic aperture
  131 Semiconductor substrate
  132 Support shaft
  133 rotor
  133a-133f Protrusion part
  134,135 opening
  136a-136c Yoke pattern
  137a to 137c coil pattern
  138 Stator
  141 Through hole
  150 Electromagnetic aperture
  151 Semiconductor substrate
  152 Support shaft
  153 rotor
  154,155 opening
  156a, 156b Magnet
  157a, 157b Coil pattern
  158 stator
  161 Through hole
  158a, 158b Stopper
  159 flange
  160a, 160b Notch

Claims (1)

A semiconductor laser for generating a light beam for irradiating the optical recording medium; a photodetector for receiving return light from the optical recording medium; a light beam for irradiating the optical recording medium; and return light from the optical recording medium. In an integrated optical unit in which a hologram element that separates
A semiconductor substrate having a reflective surface and a recess formed by etching;
The semiconductor laser is disposed in the recess so that a diverging light beam is incident on the hologram element through the reflection surface,
On the surface of the semiconductor substrate, in the vicinity of the reflecting surface, a bearing, a rotor that can be rotated electrostatically or electromagnetically with respect to the bearing, and a rotor formed on the rotor to diverge from the semiconductor laser. A diaphragm having a plurality of openings of different sizes is provided to be selectively positioned at a position where a light beam is incident through the reflecting surface and to control the diameter of the light beam to be incident on the hologram element. And the photodetector is provided at a position off the diaphragm so as to receive the return light from the optical recording medium separated by the hologram element without passing through the diaphragm. Integrated optical unit.

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