JP2005249856A - Alignment joining method, alignment joining device, and optical device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize the improvement of alignment accuracy and the improvement of joining quality in the case of joining upper and lower substrates by using a substrate holder and a substrate chuck having good flatness. <P>SOLUTION: In an alignment joining method, an alignment joining device uses a device equipped with the substrate chuck 26 composed of an optically transparent plane member, the substrate holder 25 composed of an optically transparent plane member, a stage 27 capable of moving in respective directions X, Y, Z and θ, light irradiation parts 21 and 22, and an alignment detection means 24 arranged on the substrate chuck side, and the method includes a process for setting the lower substrate 2 on the substrate chuck 26, a process for setting the upper substrate 1 on the substrate holder 25, a process for regulating the parallelism of the upper and the lower substrates, a process for regulating the thickness of an adhesive layer on a surface for bonding the upper and the lower substrates, a process for aligning the alignment marks of the upper and the lower substrates, a process for applying an adhesive, a process for spreading the adhesive, a process for controlling the thickness of the adhesive, and a process for radiating light so that the adhesive is cured to obtain an adhesive result. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an alignment bonding method and alignment bonding apparatus that align and bond upper and lower substrates, and an optical element manufactured using the alignment bonding method and alignment bonding apparatus.

  Conventionally, as a conventional technique related to an alignment apparatus used for manufacturing an optical element or the like, for example, there has been a mask aligner apparatus or the like configured as shown in FIG. In FIG. 20, reference numeral 101 denotes a light irradiation device, 102 denotes an alignment mark detection optical system for irradiating alignment light, 103 denotes a mask holder, 104 denotes a mask, 105 denotes a vacuum exhaust port, 106 denotes a mask suction groove, 107 denotes a wafer chuck, 108 is a wafer suction groove, 109 is a moving device that moves the wafer chuck in the X, Y, and θ directions, 110 is a wafer, 111 is a resist, 112 is a base that supports the wafer chuck, and 113 is a stage (not shown) that supports the base 112. A moving mechanism that moves up and down (Z direction), 114 is a device pattern, 115 is an alignment mark, and 116 is a device formed on the wafer. In this mask aligner, a wafer 110 having an alignment mark 115 provided on a device forming surface is fixed on a wafer chuck 107, and this alignment mark 115 is detected from the mask holder 103 side using an alignment mark detection optical system 102. Alignment is performed with the alignment mark 115 provided on one mask 104, and after the alignment is completed, the device pattern 114 is exposed to the alignment position.

  Usually, the alignment is performed from the state in which the film structure for forming the alignment mark 115 and the device pattern 114 and the resist film 111 for forming the resist pattern used for patterning by etching are formed. For example, the alignment mark detection optical system 102 detects and executes the alignment mark 115 through these film configurations and the resist film. Alignment detects the amount of deviation between the alignment mark position set in advance and the exposure position for device pattern formation by detecting the alignment mark, and then the wafer is positioned at the position of the wafer to be exposed so as to correct the amount of deviation. After the chuck 107 moves, exposure is performed.

  The mask holder 103 of this apparatus has a shape in which an exposure part (light irradiation range) is opened, and the mask 104 is fixed by vacuum by a vacuum suction hole or groove provided outside the opening. There was a problem. In particular, the occurrence of warpage was remarkable in a mask having a thin plate thickness. There is no example of bonding of the upper and lower substrates by this device, but if this device is used for bonding two substrates, bonding is performed on the upper and lower substrates when spreading the adhesive over the entire surface of the substrate. It is expected that the substrate on the mask holder side opened by force is deformed and cannot be bonded in a parallel state.

  In addition, when aligning from the back side of the substrate, in a general aligner apparatus, at least two alignment windows are provided on the wafer chuck side, and alignment is performed through these windows, but when the size of the substrate is changed, It was necessary to change the interval of this window. In this case, the entire wafer chuck is currently replaced. Furthermore, when the substrate size is reduced, there is a limit in fixing the substrate and forming the window, and there is a problem that it cannot cope with a small substrate. In general, since the wafer chuck is an optically opaque structure in which an aluminum (Al) plate is precisely processed and surface treatment such as fluorine is performed, an alignment window is required. In the prior art described in Patent Document 1, a plurality of alignment windows are provided on the wafer chuck, an alignment detection unit is provided on the stage below the alignment window, an alignment mark is formed on the back surface of the device, and the device is based on the alignment mark. However, since it is necessary to provide a plurality of alignment windows corresponding to the alignment detection unit on the wafer chuck, it is necessary to prepare a plurality of wafer size wafer chucks and stages. In addition, since a window is formed in the wafer chuck, problems such as a decrease in flatness when using a thin substrate and difficulty in dealing with a small substrate size are expected.

  In addition, when the alignment is performed on both sides of the substrate as in the prior art described in Patent Document 2, after the first photomask pattern and the alignment mark are transferred to the surface of the transparent substrate, the back surface of the transparent substrate is turned up. The second photomask is used, the focus of the objective lens of the microscope of the alignment apparatus is aligned with the pattern surface of the second photomask in advance, and the alignment mark in the photomask is used as a reference of the microscope. Align with the mark, then focus the microscope on the first photomask alignment mark formed on the surface of the transparent substrate, and correct the pattern displacement of the second photomask provided on the back surface of the transparent substrate Then, the resist is exposed through a second photomask, patterned, and etched to form a second photomask pattern on the back surface of the transparent substrate. While transferring the, in this case, since the formed device is exposed, it is necessary to coat such a protective film. Further, when the substrate is thick, there is a problem that the moving distance for the focal position adjustment of the microscope becomes long and the alignment accuracy is lowered.

Further, as a method for defining the parallelism of the wafer substrate and the mask substrate, there is a method of bringing the substrates into close contact and pressurizing so as to make parallel up and down. In this method, the wafer substrate is brought into contact with the mask substrate, and the applied pressure is controlled by the interference fringes generated on the contact surface. In addition, there is a method of making the force applied between the wafer substrate and the mask substrate constant by using an air spring (so-called air damper), but the repulsive force of the adhesive is more than the air spring pressure due to the viscosity of the adhesive in the actual bonding process. There is a problem that not only the adhesion thickness control but also parallelism does not occur.
Although there is a method of controlling the gap between the wafer chuck and the mask holder using a hall sensor as a gap control method, there is a drawback that the apparatus cost is increased.
In addition, after aligning optically transparent substrates, ultraviolet rays were irradiated from one side, and when curing / adhering, there was a possibility of warping on the irradiation side due to curing shrinkage of the adhesive.

Japanese Patent Publication No. 7-95515 Japanese Patent No. 2886408

The present invention has been made in view of the above circumstances, and provides an alignment bonding method and an alignment bonding apparatus that use a substrate holder and a substrate chuck with good flatness, improve alignment accuracy, and improve bonding quality. The purpose is to provide. Another object of the present invention is to provide a low-cost alignment bonding method and alignment bonding apparatus that can be applied to various substrate sizes with a single substrate holder and substrate chuck. A further object of the present invention is to provide an alignment bonding method and an alignment bonding apparatus capable of performing high-quality bonding that can perform bonding with less thickness variation of the adhesive layer and that does not warp the substrate. To do.
Furthermore, an object of this invention is to provide the optical element produced using said alignment joining method and alignment joining apparatus.

As means for achieving the above object, the present invention has the following features.
[1]. The alignment bonding method of the present invention includes a substrate chuck portion made of an optically transparent flat member for fixing a substrate, a substrate holder portion made of an optically transparent flat member, and each direction of X, Y, Z, and θ. And an unevenness formed by etching on the substrate chuck portion using an apparatus comprising a stage movable to the surface, a light irradiation portion for irradiating light, and means for detecting alignment disposed on the substrate chuck portion side A step of setting a lower substrate provided with an alignment mark having an alignment mark, a step of setting an upper substrate provided with an alignment mark having unevenness formed by etching on the substrate holder portion, and defining the parallelism of the upper and lower substrates A step, a step of defining the thickness of the adhesive layer on the surface to which the upper and lower substrates are bonded, a step of aligning the alignment marks of the upper and lower substrates, and applying an adhesive And that step, a step of spreading the adhesive, the step of controlling the thickness of the adhesive, characterized by a step of curing the adhesive the adhesive is irradiated with light (claim 1).

[2]. In the alignment joining method according to [1], grooves or holes corresponding to at least a plurality of sizes are formed on the surface of the substrate holder portion made of an optically transparent flat member for fixing the upper substrate. It is characterized (claim 2).
[3]. In the alignment bonding method according to [1] or [2], grooves or holes corresponding to at least a plurality of sizes are formed on a surface of a substrate chuck portion made of an optically transparent flat member for fixing the lower substrate. (Claim 3).
[4]. In the alignment bonding method according to any one of [1] to [3], means for sealing a vacuum suction groove or hole other than the substrate suction portion on the surface of the substrate chuck portion and the substrate holder portion is used. (Claim 4).

[5]. In the alignment bonding method according to any one of [1] to [4], the mask holder portion made of an optically transparent planar member for fixing the upper substrate is made of quartz glass ( Claim 5).
[6]. In the alignment bonding method according to any one of [1] to [5], the substrate chuck portion made of an optically transparent flat member for fixing the lower substrate is made of quartz glass. Claim 6).

[7]. In the alignment joining method according to any one of [1] to [6], a dimension is known between a substrate chuck portion for mounting and fixing the lower substrate and a substrate holder portion for fixing the upper substrate. A flat plate, a cylinder, or a sphere is inserted to define the parallelism between the alignment adhesive substrates and the thickness of the adhesive layer (Claim 7).
[8]. In the alignment bonding method according to any one of [1] to [7], alignment of the alignment marks on the upper and lower substrates is performed from the substrate chuck side (claim 8).
[9]. In the alignment bonding method according to any one of [1] to [7], the light for curing and bonding the adhesive is alternately irradiated from the optically transparent substrate chuck side and the substrate holder side. (Claim 9).

[10]. The alignment bonding apparatus of the present invention includes a substrate chuck portion made of an optically transparent flat member for fixing a substrate, a substrate holder portion made of an optically transparent flat member, and each direction of X, Y, Z, and θ. An alignment mark having an unevenness formed by etching on the substrate chuck portion, and a light irradiation portion for irradiating light, and means for detecting alignment disposed on the substrate chuck portion side. Means for setting a lower substrate provided with: means for setting an upper substrate provided with an alignment mark having irregularities formed by etching on the substrate holder portion; means for defining parallelism of the upper and lower substrates; Means for defining the thickness of the adhesive layer on the surface to which the substrate is bonded, means for aligning the alignment marks of the upper and lower substrates, means for applying an adhesive, The means according to any one of claims 1 to 9, comprising means for spreading the adhesive, means for controlling the thickness of the adhesive, and means for curing and bonding the adhesive by irradiating light. The alignment bonding method is used (claim 10).

[11]. An optical element having a structure in which substrates are bonded with an adhesive, which is manufactured using the alignment bonding method according to any one of [1] to [9].
[12]. An optical element having a structure in which substrates are bonded with an adhesive, is manufactured by the alignment bonding apparatus according to [10] (claim 12).
[13]. In the optical element according to [11] or [12], the optical element has a diffraction grating or a hologram on or between the substrates, and has a polarization separation function (claim 13).

  In the alignment joining method according to [1] of the above solution, a substrate chuck portion made of an optically transparent flat member for fixing the substrate, a substrate holder portion made of an optically transparent flat member, and X, Y , Z, θ, a device that includes a stage that can move in each direction, a light irradiation unit that irradiates light, and a unit that is disposed on the substrate chuck unit side and that detects alignment, on the substrate chuck unit. A step of setting a lower substrate provided with an alignment mark having unevenness formed by etching, a step of setting an upper substrate provided with an alignment mark having unevenness formed by etching, on the substrate holder, Aligning the alignment marks of the upper and lower substrates, the step of defining the parallelism of the substrates, the step of defining the thickness of the adhesive layer on the surface to which the upper and lower substrates are bonded Warping the upper substrate by having a step, a step of applying an adhesive, a step of spreading the adhesive, a step of controlling the thickness of the adhesive, and a step of curing and bonding the adhesive by irradiating light , The alignment accuracy and the uniform thickness of the adhesive layer can be ensured, the external dimension accuracy of the device is improved, and high-quality alignment bonding can be achieved.

  In the alignment bonding method according to [2] to [6] of the solving means, in addition to the effect of [1], at least 2 on the surfaces of the quartz glass substrate holder portion and the substrate chuck portion for fixing the upper and lower substrates. By forming a groove or hole for substrate adsorption corresponding to the type of substrate size and sealing the groove or hole other than the substrate adsorption part that deviates from the substrate size to be used, it is possible to accommodate multiple substrate sizes. In addition, there is no need to prepare a quartz glass substrate holder and a substrate chuck portion, and accordingly, the replacement process can be shortened, and the cost of the apparatus and the device can be reduced.

  In the alignment bonding method according to [7] of the solution means, in addition to the effect of any one of [1] to [6], the same dimension is provided between the substrate chuck portion and the substrate holder portion on which the upper and lower substrates are placed and fixed. By inserting a flat plate, a cylinder, or a sphere, and defining the parallelism between the alignment bonded substrates and the thickness of the adhesive layer, the bonding quality can be improved.

  In the alignment adhesion method described in [8] of the solution means, in addition to the effect of any one of [1] to [7], alignment of the alignment mark is performed from the substrate chuck portion side, thereby achieving high alignment accuracy. A bonding method can be provided. Further, it is possible to provide a bonding method that can be used for a substrate that scatters or blocks light.

  In the alignment bonding method according to [9] of the solving means, in addition to the effect of any of [1] to [8], the light for curing and bonding the adhesive is optically transparent on the substrate chuck side and the substrate holder By irradiating from the side, shrinkage due to the adhesive can be equalized, and high-quality joining is possible.

  In the alignment bonding apparatus according to [10] of the above solution, a substrate chuck portion made of an optically transparent flat member for fixing the substrate, a substrate holder portion made of an optically transparent flat member, and X, Y , Z, θ, a light irradiation unit for irradiating light, and means for detecting alignment that is arranged on the substrate chuck unit side, and is formed on the substrate chuck unit by etching Means for setting a lower substrate provided with alignment marks having unevenness, means for setting an upper substrate provided with alignment marks having unevenness formed by etching on the substrate holder portion, and parallelism of upper and lower substrates Means for prescribing, means for prescribing the thickness of the adhesive layer on the surface to which the upper and lower substrates are bonded, means for aligning the upper and lower substrate alignment marks, Claims [1] to [9] comprising means for applying an adhesive, means for spreading the adhesive, means for controlling the thickness of the adhesive, and means for curing and bonding the adhesive by irradiating light. By using the alignment bonding method according to any one of the above, an effect similar to any one of [1] to [9] can be obtained, and a high-quality and stable bonding apparatus can be provided. can do.

In the optical element according to [11] and [12] of the solving means, the alignment bonding method according to any one of [1] to [9] or the alignment bonding apparatus according to [10] is used. As a result, a high-quality optical element with good bonding quality can be obtained.
Further, in the case of a configuration having a diffraction grating or a hologram on a substrate or between substrates as in the optical element described in [13] and having a polarization separation function, polarized light capable of improving the wavefront aberration and reducing the size. A separation element can be obtained. The polarization separation element can be suitably used for an optical pickup device of an optical disk drive device.

  Hereinafter, the best mode for carrying out the present invention will be described in detail based on the embodiments shown in the drawings.

[Example 1]
First, a first embodiment of the present invention will be described with reference to FIGS.
FIG. 1 is a schematic cross-sectional view of a wafer-like bonded substrate 40 having a diameter of φ100 mm on which a large number of optical elements are formed. The bonded substrate 40 is formed on a glass substrate made of BK-7 having a diameter of φ100 mm and a thickness of 1.00 mm. An organic birefringent film 3 having a diameter of 80 mm and a thickness of 0.10 mm is formed on an upper substrate 1 on which a lattice 8 and an alignment mark 9 are formed, and a glass substrate made of BK-7 having a diameter of 100 mm and a thickness of 1.00 mm. After being bonded with an ultraviolet curable adhesive 6 having the same refractive index as that of the film 3 in the center, a lower substrate 2 having a large number of diffraction gratings (or holograms) 10 and alignment marks 11 formed on the organic birefringent film, An adhesive 5 for bonding the substrate 1 and the lower substrate 2, an adhesive 7 for filling the grooves of the diffraction grating 10, and a protective substrate 4 bonded to the lower substrate 2 with an organic birefringence film by the adhesive 7. Completed There. A large number of optical elements can be obtained by cutting the bonding substrate 40 into a plurality of pieces with a dicing saw or the like to be described later. Hereinafter, a specific method for manufacturing the bonding substrate 40 will be described.

  First, a transparent substrate made of shot optical glass BK-7 having a diameter of φ100 mm and a thickness of 1.00 mm constituting the lower substrate 2 was placed on a substrate fixing table of a spin coater (not shown), and vacuum-adsorbed and fixed. Thereafter, while rotating the substrate fixing table at 10 to 50 rpm, about 10 g of the epoxy resin-based UV curable adhesive 6 having a refractive index of 1.52 and a viscosity of 500 cps (25 ° C.) is applied to the center portion of the lower substrate 2 using a dispenser. It was dripped. Thereafter, the substrate fixing table was rotated at 300 to 500 rpm, the ultraviolet curable adhesive 6 was spread over the entire lower substrate, and the rotation of the substrate fixing table was stopped. Thereafter, the center of the organic birefringent film 3 having a diameter of 80 mm and a thickness of 100 μm was aligned with the center of the lower substrate 2 and placed on the adhesive surface on the lower substrate using a mounting device. Thereafter, the substrate fixing table was rotated at 1000 to 2000 rpm, the ultraviolet curable adhesive 6 was shaken off, and the surface of the organic birefringent film 3 was flattened with the adhesive layer thickness kept constant within the lower substrate surface. Thereafter, the rotation of the substrate fixing table was stopped, and ultraviolet rays were irradiated from the organic birefringent film side using a high-pressure mercury lamp to cure the ultraviolet curable adhesive 6. The adhesive thickness after curing at this time was 20 μm.

  Next, the lower substrate 2 to which the organic birefringent film 3 was adhered was removed from the substrate fixing table, a positive resist was applied on the organic birefringent film to a thickness of 1.1 μm, and prebaked at 90 ° C. for 30 minutes. After that, the lower substrate 2 is mounted on a reduction projection exposure apparatus (NA = 0.45, σ = 0.6, wavelength; i-line), and a 2.0 μm line-and-space device pattern having 1000 cycles and a line width Exposure was performed using a cross-shaped alignment pattern of 30 μm and a length of 130 μm, and a reticle having a diameter of φ100 μm for alignment of the outer shape. Next, development was performed using a developer NMD-3, and post-baking was performed at 100 ° C. for 30 minutes to complete a periodic resist pattern. Thereafter, aluminum (Al) is vapor-deposited on the resist pattern by sputtering, and subsequently the resist is dissolved using acetone to lift off the Al to complete an Al pattern in which the resist pattern is inverted. Using an NLD-800 etching apparatus manufactured by Vacuum Technology Co., Ltd., the organic birefringent film 3 was formed using the Al pattern as a metal mask under the etching conditions of substrate bias 200 W, antenna power 1 KW, oxygen gas 40 SCCM, substrate temperature −30 ° C. Etching to a depth of 4 μm. Thereafter, the Al pattern was removed using a phosphoric Al etching solution to complete a concavo-convex grating (hereinafter referred to as a diffraction grating) 10 having 1000 cycles and a concavo-convex alignment mark 11. 2A is a plan view and a cross-sectional view of the completed lower substrate. FIG. 3A is an external alignment mark 11a formed as an alignment mark 11 on the organic birefringent film 3 of the lower substrate 2 and a device. The alignment mark 11b is shown.

One upper substrate 1 is composed of a transparent substrate made of shot optical glass BK-7 having a diameter of 100 mm and a thickness of 1.00 mm. First, a positive resist is formed on the upper substrate to a thickness of 1.1 μm. After coating and pre-baking at 90 ° C. for 30 minutes, the upper substrate 1 is mounted on a reduction projection exposure apparatus (NA = 0.45, σ = 0.6, wavelength; i-line), and 5 μm lines with 1000 cycles Exposure was performed using a reticle having an and space device pattern and a cross-shaped alignment pattern having a line width of 20 μm and a length of 110 μm. Next, development was performed using a developer NMD-3, and post-baking was performed at 100 ° C. for 30 minutes to complete a periodic resist pattern. Then, using an NLD-800 etching apparatus manufactured by Nippon Vacuum Technology Co., Ltd., with the resist pattern as a mask under etching conditions of substrate bias 200 W, antenna power 1.5 kW, CF ₄ gas 60 SCCM, substrate temperature −30 ° C. Etching to a depth of 5 μm. Thereafter, the resist was dissolved and removed using acetone to complete the concavo-convex lattice 8 having 1000 cycles and the concavo-convex alignment mark 9. 2B is a plan view and a cross-sectional view of the completed upper substrate, and FIG. 3B shows a device alignment mark formed as an alignment mark 9 on the upper substrate 1.

Further, the protective substrate 4 is composed of a transparent substrate made of shot optical glass BK-7 having a diameter of 100 mm and a thickness of 1.00 mm. First, a positive resist is applied to the protective substrate to a thickness of 1.1 μm. After pre-baking at 90 ° C. for 30 minutes, the protective substrate 4 is mounted on a reduction projection exposure apparatus (NA = 0.45, σ = 0.6, wavelength; i-line), and an alignment pattern with a diameter of 80 μm is mounted. Exposure was performed using a reticle. Next, development was performed using a developer NMD-3, and post-baking was performed at 100 ° C. for 30 minutes to complete a resist pattern. Then, using an NLD-800 etching apparatus manufactured by Nippon Vacuum Technology Co., Ltd., with the resist pattern as a mask under etching conditions of substrate bias 200 W, antenna power 1.5 kW, CF ₄ gas 60 SCCM, substrate temperature −30 ° C. , Etched to a depth of 5 μm. Thereafter, the resist was dissolved and removed using acetone to complete the alignment mark 12 for aligning the outer shape of the substrate. FIG. 2C is a plan view and a cross-sectional view of the completed protective substrate, and FIG. 3C shows a device alignment mark formed as the alignment mark 12 on the protective substrate 4.

  FIG. 4 is a schematic cross-sectional view of an alignment bonding apparatus showing an embodiment of the present invention. The alignment bonding apparatus 20 includes an upper light irradiation device 21, a lower light irradiation device 22, a lower irradiation light reflection device 23, an alignment detection optical system 24 that detects alignment marks by irradiating alignment light, and a vacuum exhaust port. A quartz glass mask holder (substrate holder portion) 25 having a diameter φ of 250 mm and a thickness of 20 mm having a plurality of substrate suction grooves (width 1 mm, depth 0.3 mm) 33 having a diameter of 32, 4 inches, 6 inches, and 8 inches. A quartz glass wafer chuck having a diameter of 250 mm and a thickness of 15 mm having a vacuum exhaust port 34 and a substrate suction groove 35 having a diameter of 4 inches, 6 inches and 8 inches (width 1 mm, depth 0.3 mm) (substrate chuck) Part) 26, a stage 27 on which a quartz glass wafer chuck is placed, and a stage moving device that moves the stage in each of the X, Y, and θ directions. 28, a Z-axis movement control device 29 that moves the stage 27 in the vertical direction (Z direction), a base 30 to which the Z-axis movement control device 29 is fixed, a gantry 31 to which the base 30 is fixed, and an adhesive (not shown) It is comprised from the agent dripping apparatus. The upper and lower light irradiation devices 21 and 22 have shutters (not shown) built therein.

Hereinafter, a bonding method in the case where the protective substrate 4 and the upper substrate 1 are bonded to the lower substrate 2 illustrated in FIG. 2 using the alignment bonding apparatus 20 having the configuration illustrated in FIG. 4 will be described.
First, the polyester film 36 having the substrate suction window is mounted and fixed on the quartz glass mask holder 25, and the vacuum suction groove 33 other than the substrate suction portion is sealed. Then, the protective substrate 4 made of the shot optical glass BK-7 having a diameter of 100 mm and a thickness of 0.50 mm made by the method described above was placed on the substrate suction window and fixed to the quartz glass mask holder 25 by vacuum suction. . Next, the external alignment mark 12 on the protective substrate 4 is detected by the alignment detection optical system (microscope with image storage device) 24, and the mark 12 is sandwiched between the cross lines on the monitor of the image storage device as shown in FIG. , Memorize this image.

  Next, as shown in FIG. 6A, a polyester film 37 having a thickness of 0.1 mm cut out to an inner diameter of 110 mm and an outer diameter of 210 mm to seal the 6-inch and 8-inch substrate suction grooves 35 is made of quartz glass. It was placed on the wafer chuck 26. Thereafter, as shown in FIG. 6B, the lower substrate 2 made by the above-described method was fixed to the quartz glass wafer chuck 26 by vacuum suction.

Next, as shown in FIG. 7, between the quartz glass wafer chuck 26 and the quartz glass mask holder 25, a zirconia cylinder having a diameter of 5 mm, a height of 5.000 mm, a parallelism of 0.001 mm, and a surface roughness Ra <10 nm. 3 are inserted at positions equal to 120 ° on the same circumference by movement of a support arm (not shown), the stage 27 is raised by the Z-axis movement control device 29, and the quartz glass wafer chuck 26 and quartz glass are inserted. A zirconia cylinder 37 was sandwiched between the mask holders 25, and the point where pressure was applied and stopped at 1 N / piece was stored and fixed as a gap of 5.000 mm and a parallel surface.
Thereafter, the quartz glass wafer chuck 26 was lowered together with the stage 27 by the Z-axis movement control device 29, and the zirconia cylinder 38 was moved out of the substrate.

  Next, the lower substrate 2 is extruded in the left direction in the figure, and a UV curable epoxy resin adhesive EX1500-4 manufactured by Otex Co., Ltd., having a viscosity of 1000 cps (23 ° C.) is used at the center of the lower substrate 2. ) Was dropped, the lower substrate 2 was returned to the right in the figure, and the quartz glass wafer chuck 26 was lifted together with the stage 27 by the Z-axis movement control device 29 to a gap that secures an adhesive layer thickness of 100 μm or more.

  Next, as shown in FIG. 8, the alignment of the outer alignment marks 11a and 12 on the lower substrate 2 and the protective substrate 4 was detected by an alignment detection optical system (microscope with an image storage device) 24 to perform alignment. First, as shown in FIG. 8A, the focus position of the microscope is adjusted to the lower substrate 2 to detect the outer alignment mark 11a on the lower substrate 2, and the outer alignment mark 12 on the protective substrate 4 is stored. After detecting an error between the crosshair image on the monitor of the image storage device and the detected outer alignment mark 11a (deviation from the crosshairs storing the image), as shown in FIG. Correction was performed by moving the quartz glass wafer chuck 26 in the X, Y, and θ directions by the moving device 28. FIG. 8C shows alignment marks 11a and 12 on the lower substrate 2 and the protective substrate 4 after alignment.

  This was carried out at at least two points 50 mm apart on the same line within the substrate surface. After the alignment correction, the quartz glass wafer chuck 26 is fixed to the stage 27 by vacuum suction or the like. Thereafter, in order to secure a final adhesive thickness of 50 μm, the quartz glass wafer chuck 26 is raised together with the stage 27 by the Z-axis movement control device 29 again, and the adhesive 7 is spread over the entire substrate as shown in FIG. The gap was stopped at a position of 1.700 mm, and this state was maintained for 2 minutes while the adhesive 7 was sufficiently spread. At this time, the total thickness of the substrates 2 and 4 is 1.500 mm, the thickness of the organic birefringent film 3 is 0.100 mm, the adhesive thickness of the lower substrate 2 and the organic birefringent film 3 is 0.050 mm, The adhesive thickness of the protective substrate 4 is 0.050 mm.

Next, as shown in FIG. 9, after the alignment detection optical system is moved out of the light irradiation range by a moving device (not shown), the upper and lower light irradiation devices 21, 22 have a wavelength of 365 nm and a light intensity of 40 mW / mm on the entire surface of the adhesive. The adhesive 7 was cured by irradiating with 50 cm ² of ultraviolet rays (UV) alternately every 2 seconds. For light irradiation, the shutter was switched to prevent one ultraviolet light from entering the other light irradiation device.
Thereafter, the vacuum suction of the quartz glass mask holder 25 is turned off, and the vacuum suction of the protective substrate 4 is released. Next, after the quartz glass wafer chuck 26 is lowered together with the stage 27 by the Z-axis movement control device 29, the vacuum suction of the quartz glass wafer chuck 26 is cut off, and the lower substrate 2 to which the protective substrate 4 is aligned and bonded is taken out. A lower substrate 2 with a protective substrate having a cross-sectional structure as shown in FIG.

Next, alignment bonding of the upper substrate 1 and the lower substrate 2 with the protective substrate was performed.
First, after fixing the upper substrate 1 made of BK-7 having a diameter of 100 mm and a thickness of 1.000 mm made by the above-described method to the quartz glass mask holder 25 by vacuum suction (in FIG. 4, the protective substrate 4 is attached to the upper substrate). 1), the alignment mark 9 is detected by the alignment detection optical system (microscope with image storage device) 24, and as shown in FIG. 11, the mark 9 is sandwiched between crosshairs on the monitor of the image storage device, This image is stored.

  Next, after the lower substrate 2 with a protective substrate is fixed to the quartz glass wafer chuck 26 by vacuum suction, a diameter φ of 5 mm, a height of 5.000 mm, and parallel between the quartz glass wafer chuck 26 and the quartz glass mask holder 25 are provided. After inserting three zirconia cylinders 38 having a degree of 0.001 mm and a surface roughness Ra <10 nm at equal positions of 120 ° on the same circumference by the movement of a support arm (not shown), the stage 27 is moved by the Z-axis movement controller 29. At the same time, the quartz glass wafer chuck 26 is raised, and a zirconia cylinder 38 is sandwiched between the quartz glass wafer chuck 26 and the quartz glass mask holder 25 (in FIG. 7, the protective substrate 4 is replaced with the upper substrate 1 and the lower substrate 2 is protected). The state where it is replaced with the lower substrate 2 with the substrate) The point where the pressure is stopped at 1 N / piece is the gap 5.000 mm and the parallel surface. And memorized and fixed. Thereafter, the quartz glass wafer chuck was lowered together with the stage 27 by the Z-axis movement control device 29, and the zirconia cylinder 38 was moved out of the substrate.

  Next, the lower substrate 2 with the protective substrate is extruded in the left direction in the drawing, and a UV curable epoxy resin adhesive EX1500-4 manufactured by Otex Co., Ltd., having a viscosity of 1000 cps is used at the center of the lower substrate 2. 0.5 mL of (23 ° C.) is dropped, the lower substrate 2 is returned to the right in the drawing, and the quartz glass wafer chuck is lifted together with the stage 27 by the Z-axis movement control device 29 to the gap that secures an adhesive layer thickness of 100 μm or more. did.

  FIG. 12A shows the crosshairs in which the alignment mark 9 of the upper substrate 1 is sandwiched and stored on the monitor screen of the image storage device, and the alignment marks 11a, 11b, and 12 of the lower substrate 2 with the protective substrate. ) Shows alignment marks 9, 11a, 11b, and 12 on the upper substrate 1 and the lower substrate 2 with the protective substrate after alignment. First, the focus position of the microscope of the alignment detection optical system (microscope with image storage device) 24 is aligned with the organic birefringent film 3 of the lower substrate 2 with the protective substrate, and the alignment marks 11a and 11b on the organic birefringent film 3 are aligned. An error between the alignment mark image of the upper substrate 1 that has been detected and stored in advance and the detected alignment mark (deviation from the crosshair that stores the image) is detected. Then, the position was corrected by moving the wafer chuck 26 in each of the X, Y, and θ directions by the stage moving device 28. This was carried out at at least two points 50 mm apart on the same line within the substrate surface. After the alignment correction, the quartz glass wafer chuck 26 is fixed to the stage 27 by vacuum suction or the like.

  Next, in order to secure a final adhesive thickness of 50 μm, the quartz glass wafer chuck 26 is raised together with the stage 27 by the Z-axis movement control device 29 again, and the adhesive 5 is pushed over the entire substrate as shown in FIG. Spreading and stopping at the position of gap 2.750 mm, this state was maintained for 2 minutes while the adhesive 5 was sufficiently spread. At this time, the thickness of the upper substrate is 1.000 mm, the thickness of the lower substrate with the protective substrate is 1.700 mm, and the thickness of the adhesive layer is 0.050 mm.

Next, as shown in FIG. 13, after the alignment detection optical system 24 is moved out of the light irradiation range by a moving device (not shown), the upper and lower light irradiation devices 21, 22 have a wavelength of 365 nm and a light intensity of 40 mW on the entire surface of the adhesive. The adhesive 5 was cured by irradiating 50 times of / cm ² of ultraviolet rays (UV) alternately for 2 seconds.
For light irradiation, the shutter was switched to prevent one ultraviolet light from entering the other light irradiation device. Thereafter, the vacuum suction of the quartz glass mask holder 25 is turned off, and the vacuum suction fixation of the upper substrate 1 is released. Next, after the quartz glass wafer chuck 26 is lowered together with the stage 27 by the Z-axis movement control device 29, the vacuum suction of the quartz glass wafer chuck 26 is cut off, and the upper substrate 1 is aligned and bonded to the lower substrate 2 with the protective substrate. Remove the substrate. Thereby, the bonded substrate 40 having a cross-sectional structure as shown in FIG. 1 is obtained.

  As shown in FIG. 14, the alignment bonded substrate 40 was cut into a size of 6 mm square (6 mm × 6 mm) by a dicing saw 41 of a dicing apparatus, and a large number of optical elements 42 were cut out. As shown in FIG. 1, the optical element 42 has a diffraction grating 10 composed of an organic birefringent film 3 between upper and lower substrates, and transmits outgoing light and transmitted light and diffracted light according to the polarization state of incident light. This is a polarization separation element having a polarization separation function for separating the light into two. In the present embodiment, an example is shown in which the periodic concavo-convex grating (diffraction grating) 10 is formed on the organic birefringent film 3 adhered to the lower substrate 2. However, if a hologram is formed on the organic birefringent film 3, a polarization hologram It becomes an element.

In this embodiment, long gap alignment is performed with the alignment mark interval in the Z direction between the upper and lower substrates being 0.5 mm away from the maximum of 2.15 mm, and the alignment interval is about four times that of the conventional mask alignment apparatus. The material of the mask holder (substrate holder) 25 and the wafer chuck (substrate chuck) 26 is a material that transmits the wavelengths used for the upper and lower light irradiation devices 21 and 22 and the alignment detection optical system 24, and has a Young's modulus equivalent to that of quartz glass or More than that is sufficient, but quartz glass is more suitable in consideration of ultraviolet transmittance, material cost, processing cost, and the like.
In addition, the upper and lower substrates are fixedly integrated by vacuum suction with a mask holder (substrate holder) 25 and a wafer chuck (substrate chuck) 26 made of optically flat quartz glass. Therefore, when the adhesive is spread over the entire surface of the substrate, deformation of the substrate due to the force applied to the substrate surface can be prevented.
The mask holder (substrate holder) 25 and wafer chuck (substrate chuck) 26 have vacuum suction grooves 33 and 35 for fixing a plurality of substrates corresponding to a plurality of substrate sizes. By sealing with polyester films 36 and 37, one set of mask holder (substrate holder) 25 and wafer chuck (substrate chuck) 26 can cope with a plurality of substrate sizes, and it is necessary to prepare mask holders and wafer chucks of various sizes. There is no.

Furthermore, in the past, parallel alignment of substrates and alignment gap reference alignment were performed with the substrates in contact with each other, but in the method of this example, by inserting a reference zirconia cylinder on the surface from which the substrate was removed, Damage to resist patterns and devices formed on the substrate surface can be prevented.
In addition, since the ultraviolet rays are alternately irradiated from both sides of the adhesive in the adhesive curing step, the curing shrinkage of the adhesive can be equalized and the warpage of the substrate can be reduced.
Moreover, although the example which moves the focus of the microscope of the alignment detection optical system 24 was shown in order to detect the alignment mark of an upper and lower board | substrate, a microscope is fixed and each board | substrate is moved to a predetermined | prescribed focus position, and it aligns. The method may be used.

The material of the substrate is not limited to borate crown glass (BK-7), but is a transparent glass substrate such as quartz glass, borosilicate glass, fluorinated crown glass, barium crown glass, crown glass, polyester, etc. Alternatively, a polymer film such as acryl, a sheet, a plate, or the like may be used. Further, although an ultraviolet curable epoxy resin adhesive is used as the adhesive, an acrylic resin adhesive may be used. In this embodiment, the zirconia cylinder 38 is used as a member that is inserted between the mask holder (substrate holder) 25 and the wafer chuck (substrate chuck) 26 and defines the alignment between the alignment adhesive substrates and the thickness of the adhesive layer. there may be a zirconia ball or flat, also, the material is alumina, alumina nitride, silicon carbide, silicon nitride, c-BN, TiN, and ceramics such as ZrSiO _4, WC, WC-Co alloy, WC A so-called cemented carbide such as a TiC-Co alloy may be used. In this embodiment, the thickness and the diameter are 5 mm, but the thickness and the diameter are not limited to 5 mm. The thickness and the diameter may be changed depending on the substrate thickness to be used, the target adhesive layer thickness, and the like. Similarly, although the cross-sectional shape is circular, it is not limited to this shape, and may be a polygon, an ellipse, or the like. In consideration of contact with the apparatus, it is desirable to chamfer corners (for example, 0.3R or 0.3C).

Next, when the upper and lower substrates are joined with the apparatus of this example and the conventional apparatus, the alignment accuracy after bonding in the diameter φ80 mm range, the warpage (planarity), and the total thickness variation of the upper and lower substrates are compared and measured. It is shown in Table 1 below.
In addition, with respect to the alignment accuracy of 5 μm with a gap of 2000 μm, the error is larger than 5 μm, and the smaller one is marked as ◯. Further, with respect to the target substrate flatness of 10 μm or less after bonding within a diameter of φ80 mm, the case where the warpage was larger than 10 μm was marked as “X”, and the small one was marked as “◯”. With respect to the target adhesive layer thickness of 50 μm, those having a thickness larger than ± 10 μm were rated as “x”, and those having a smaller thickness were evaluated as “◯”. The alignment accuracy was measured with an optical microscope for the center misalignment of the alignment mark, the flatness with a stylus type roughness meter, and the thickness of the adhesive layer was observed and measured with a metal microscope after the sample was cut by dicing.

  As shown in Table 1, in the conventional bonding method, the alignment accuracy error, warpage (flatness), and overall thickness variation of the upper and lower substrates were large, but in the bonding method of this example, the alignment accuracy error and warpage (flatness) were small. Also, the overall thickness variation of the upper and lower substrates is small. In addition, when the warpage (flatness) and the upper and lower substrate total thickness variation are larger than the target values, the optical characteristics of the optical element, particularly the wavefront aberration, is deteriorated. However, in the joining method of this embodiment, an error in alignment accuracy occurs. Further, since the warpage (flatness) and the variation in the total thickness of the upper and lower substrates are small, it is possible to provide an optical element (such as a polarization separation element) in which the reduction of wavefront aberration is improved.

[Example 2]
Next, a second embodiment of the present invention will be described with reference to FIGS.
In this embodiment, the lower substrate (hereinafter referred to as the lower substrate) 2 with the organic birefringent film having the structure shown in FIG. 2A and the upper substrate 1 having the structure shown in FIG. 2B are used. Is manufactured by the same method as in Example 1, and the description is omitted here. The difference is that the substrate suction groove of the quartz glass mask holder 25 and the quartz glass wafer chuck 26 of the alignment bonding apparatus shown in the first embodiment is changed to a hole, and a wafer-like substrate having a maximum diameter of 8 inches and a minimum of 10 mm. Or a point corresponding to a square substrate up to 10 mm square.

Specifically, as shown in FIG. 15, a quartz glass wafer chuck (substrate chuck) 26 'having a diameter of 250 mm and a thickness of 20 mm is provided on the outermost periphery corresponding to a substrate having a diameter of 4, 5, 6 or 8 inches. The vacuum suction holes 43a having a diameter of 0.5 mm are formed at equal intervals of 15 degrees at the positions, and the diameter of 0.5 mm corresponding to a substrate having a diameter of 3 inches or less within a 50 mm square of the center of the quartz glass wafer chuck 26 '. The adsorption holes 43b were formed at a pitch of 5 mm.
As a more specific manufacturing method of the quartz glass wafer chuck (substrate chuck) 26 ', first, a quartz glass 26a having a diameter of 250 mm and a thickness of 10 mm is drilled at a position corresponding to the above dimensions with a polishing drill having a diameter of 0.4 mm. Then, the side surface of the hole was made transparent by diamond polishing. On the other hand, a recess 44a having a diameter of 180 mm and a depth of 3 mm was processed in a quartz glass 26b having a diameter of 250 mm and a thickness of 10 mm, and a vacuum exhaust groove 44b communicating from the vacuum exhaust port 34 was provided in the recess 44a. The processed surface was made transparent by flame treatment. The two processed quartz glasses 26a, 26b are heat-sealed along the mating surfaces, with the processed surfaces of the recesses 44a having a diameter of 180 mm and a depth of 3 mm, with the processed surfaces of the quartz glasses 26a, 26b being matched. Thereafter, the parallelism was λ / 10, the flatness was 100 nm, and the surface roughness (Rt) was 1 nm by double-side polishing. After polishing, ultrasonic cleaning using pure water was performed to remove polishing powder.

On the other hand, the quartz glass mask holder (substrate holder) 25 'side is also manufactured by the same method with the same dimensions as the quartz glass wafer chuck 26'.
These quartz glass mask holder (substrate holder) 25 ′ and quartz glass wafer chuck (substrate chuck) 26 ′ were attached to an alignment bonding apparatus 20 ′ having the same configuration as in the first embodiment.

In the present embodiment, alignment bonding between 10 mm square substrates is described. Similar to the first embodiment, the upper substrate 1 has a 10 μm square, 1.000 mm thick BK-7 substrate on which a 20 μm line and space depth of 10 μm, which is 100 cycles by photolithography and dry etching processes. And a cross-shaped alignment mark having a line width of 20 μm and a length of 100 μm were formed.
The lower substrate 2 is also subjected to photolithography and dry etching processes similar to those of the first embodiment, and 500 μm of 5 μm line-and-and-on are formed on an organic birefringent film bonded to a 10 mm square and 1.000 mm thick BK-7 substrate. A lattice-like device pattern having a space depth of 10 μm and a cross-shaped alignment mark having a line width of 20 μm and a length of 100 μm were formed.

  FIG. 16 is a schematic sectional view of an alignment bonding apparatus showing a second embodiment of the present invention. The alignment bonding apparatus 20 ′ includes an upper light irradiation apparatus 21, a lower light irradiation apparatus 22, a lower irradiation light reflecting apparatus 23, an alignment detection optical system 24 that detects alignment marks by irradiating alignment light, and the above-described alignment bonding apparatus 20 ′. A quartz glass mask holder (substrate holder) 25 ′ having a substrate suction hole 45 manufactured by the method, a quartz glass wafer chuck (substrate chuck) 26 ′ having a substrate suction hole 43 manufactured by the method described above, and A stage 27 on which a quartz glass wafer chuck is placed, a stage moving device 28 that moves the stage in each of the X, Y, and θ directions, and a Z-axis movement control device that moves the stage 27 in the vertical direction (Z direction). 29, a base 30 to which the Z-axis movement control device 29 is fixed, a gantry 31 to which the base 30 is fixed, and an adhesive dripping device (not shown) Is configured, quartz glass mask holder 25 'on the substrate 1 in the vacuum-sucked, quartz glass wafer chuck 26' the organic birefringent film with lower substrate 2 are vacuum suction. An acrylic sheet 47 for sealing a vacuum suction hole other than the substrate suction portion is mounted and fixed to the quartz glass mask holder 25 'and the quartz glass wafer chuck 26'. FIG. 17 shows a plan view of a quartz glass mask holder 25 ′ on which an acrylic sheet 47 having a substrate placement window is mounted (the quartz glass wafer chuck 26 ′ has the same sheet shape). FIG. 16 shows a state in which a zirconia spacer 46 is inserted between the quartz glass mask holder 25 ′ and the quartz glass wafer chuck 26 ′. The upper and lower light irradiation devices 21 and 22 have shutters (not shown) built therein.

Hereinafter, a bonding method in the case where the upper substrate 1 is bonded to the lower substrate 2 with the organic birefringent film using the alignment bonding apparatus 20 ′ having the configuration shown in FIG. 16 will be described.
First, the upper substrate 1 made by the above-described method was set on the substrate placement window 47a of the acrylic sheet 47 of the quartz glass mask holder 26 'and fixed by vacuum suction.
Next, an alignment mark is detected by an alignment detection optical system (microscope with image storage device) 24, the mark is sandwiched between crosshairs on a monitor of the image storage device, and this image is stored.

  Next, the lower substrate 2 made by the above-described method is set on the substrate mounting window of the acrylic sheet 47 of the quartz glass wafer chuck 26 ′, fixed by vacuum suction, and then the quartz glass wafer chuck 26 ′ and the quartz glass are fixed. Between the mask holders 25 ', a zirconia spacer 46 having a diameter of 20 mm, a height of 3.000 mm, a parallelism of 0.001 mm, and a surface roughness Ra <10 nm is equally divided by 120 ° on the same circumference by moving a support arm (not shown). Then, the Z-axis movement control device 29 raises the quartz glass wafer chuck 26 'together with the stage 27, and the zirconia spacer 46 is interposed between the quartz glass wafer chuck 26' and the quartz glass mask holder 25 '. And pressurizing at 1 N / piece, storing and fixing the stopped point as a parallel plane, and then the Z-axis movement control device 29 As a result, the quartz glass wafer chuck 26 'was lowered together with the stage 27, and the zirconia spacer 46 was moved out of the substrate.

  Next, the lower substrate 2 is extruded in the left direction in the figure, and a UV curable epoxy resin adhesive EX1500-4 manufactured by Otex Co., Ltd., having a viscosity of 1000 cps (23 ° C.) is used at the center of the lower substrate 2. ) Is dropped, and the lower substrate 2 is returned to the right in the figure, and the diameter φ is 20 mm and the height is 2.150 mm (= upper substrate) between the quartz glass wafer chuck 26 ′ and the quartz glass mask holder 25 ′. (Not shown) zirconia spacer 46, which is a reference dimension after bonding, having a thickness of 1.000 mm + lower substrate thickness with an organic birefringent film 1.100 mm + adhesion layer thickness 0.050 mm), parallelism 0.001 mm, and surface roughness Ra <10 nm After inserting three at 120 ° equally divided positions on the same circumference by the movement of the arm, move to the Z-axis to a gap that secures an adhesive layer thickness of 100 μm or more It rose quartz glass wafer chuck 26 'together with the stage 27 by a control device 29.

  Next, the same alignment method as in Example 1 is performed, and the focus position of the microscope of the alignment detection optical system (microscope with image storage device) 24 is aligned with the alignment mark on the organic birefringent film 3 of the lower substrate 2, so An alignment mark on the refractive film is detected, and an error between the alignment mark image of the upper substrate stored in advance and the detected alignment mark (deviation between the crosshairs storing the image) is detected. The position was corrected by moving the quartz glass wafer chuck 26 ′ in the X, Y, and θ angular directions by the stage moving device 28. This was performed at at least two points 6 mm apart on the same line in the substrate plane. After correcting the alignment position, the quartz glass wafer chuck 26 'is fixed to the stage 27 by vacuum suction or the like. Thereafter, in order to secure the final adhesive thickness of 50 μm, the quartz glass wafer chuck 26 ′ is lifted together with the stage 27 by the Z-axis movement control device 29 again to spread the adhesive 5 over the entire substrate and come into contact with the zirconia spacer 46. This position was maintained for 2 minutes while the adhesive 5 was sufficiently spread.

Next, after the alignment detection optical system 24 is moved outside the light irradiation range by a moving device (not shown), the upper and lower light irradiation devices 21 and 22 emit ultraviolet rays having a wavelength of 365 nm and a light intensity of 40 mW / cm ^{2 over} the entire surface of the adhesive. The adhesive 5 was cured by alternately irradiating 50 times each for 2 seconds. For light irradiation, the shutter was switched to prevent one ultraviolet light from entering the other light irradiation device. Further, in this embodiment, the acrylic sheet 47 on the quartz glass mask holder 25 ′ and the quartz glass wafer chuck 26 ′ has a function of both vacuum sealing and light shielding so as not to irradiate light other than the substrate.

  Thereafter, the vacuum suction of the quartz glass mask holder 25 ′ is turned off, and the vacuum suction fixation of the upper substrate 1 is released. Next, after the quartz glass wafer chuck 26 'is lowered together with the stage 27 by the Z-axis movement control device 29, the vacuum suction of the quartz glass wafer chuck 26' is cut off, the vacuum suction fixation of the lower substrate 2 is released, and the upper and lower The bonded substrate to which the substrate is aligned and bonded is taken out.

  The alignment bonded substrate was cut into a size of 6 mm square (6 mm × 6 mm) by a dicing saw 41 of a dicing apparatus as shown in FIG. 14, and a large number of optical elements were cut out. This optical element has a diffraction grating 25 composed of an organic birefringent film 23 between upper and lower substrates, and has a polarization separation function for separating outgoing light into transmitted light and diffracted light according to the polarization state of incident light. It is an optical element (polarization separation element). In the present embodiment, an example is shown in which the periodic concavo-convex grating (diffraction grating) 10 is formed on the organic birefringent film 3 adhered to the lower substrate 2. However, if a hologram is formed on the organic birefringent film 3, a polarization hologram It becomes an element.

  As described above, in this embodiment, the quartz glass mask holder 25 ′ and the quartz glass wafer chuck 26 ′ are not replaced depending on the size of the substrate, and a circular substrate having a maximum diameter of 8 inches and a minimum of 10 mm, or a 10 mm square. It can correspond to a square substrate. Further, in such a small substrate size joining, a decrease in parallelism becomes a problem, but by inserting a zirconia spacer 46 having a reference thickness between the quartz glass mask holder 25 ′ and the quartz glass wafer chuck 26 ′, The accuracy of the parallelism of the substrates after bonding can be improved. In particular, the accuracy can be improved regardless of the positions where the upper and lower substrates are placed on the quartz glass mask holder 25 'and the quartz glass wafer chuck 26'.

  As described above, the alignment bonding method and apparatus of the present invention is an optical element having a structure in which two or more substrates are bonded with an adhesive, particularly an optical element having an optical device such as a diffraction grating or a hologram on or between the substrates. It can utilize suitably for preparation of an element. Since the optical element according to the present invention, particularly the polarization separation element bonded by the above-described bonding method and apparatus, has good parallelism and can reduce the occurrence of wavefront aberration, the optical pickup apparatus of the optical disk drive apparatus, etc. It can utilize suitably for an optical apparatus.

Here, FIG. 18 is a schematic configuration diagram showing a configuration example of an optical pickup device using an optical element (polarization separation element) according to the present invention, and a CD (compact disc) type optical disc (CD, CD-) as an optical recording medium. 2 is a configuration example of an optical pickup device using R, CD-RW, and the like.
In the optical pickup device for CD, light having a wavelength of 780 nm emitted from the laser diode 91 irradiates the CD optical disk 95 through the polarization separation element 92, the collimator lens 93, and the objective lens 94. The reflected light from the recording pit passes through the objective lens 94 and is diffracted by the polarization separation element 92 and guided to the photodiode 96, and focus detection, track detection, and signal detection are performed. In this optical pickup device, as the polarization separation element 92, the polarization separation element 52 manufactured by the alignment bonding method and apparatus of Example 1 or 2 is used.

When a signal was recorded on a CD-RW using the optical pickup device having the configuration shown in FIG. 18, and then the signal was reproduced by the same optical pickup device, a beam splitter and a quarter-wave plate bonded with a conventional prism were used. A reproduction signal output equivalent to that of a CD optical pickup device combined with (λ / 4 plate) can be obtained, and it is confirmed that the optical pickup device of this example has recording / reproduction characteristics equivalent to those of a conventional optical pickup device. did it.
In this optical pickup device, the polarization separation element 92 is smaller than the conventional beam splitter to which the prism is bonded, and the grating 8 is formed on the upper substrate 1 of the polarization separation element to function as a λ / 4 plate. Therefore, the size can be reduced as compared with the conventional optical pickup device.

Next, FIG. 19 is a schematic configuration diagram showing another configuration example of the optical pickup device. As an optical recording medium, a DVD (Digital Versatile Disc) optical disc (DVD, DVD-R, DVD-RW, DVD-ROM, DVD) is used. This is a configuration example of an optical pickup device using a RAM or the like.
In a DVD optical pickup device, light having a wavelength of 680 nm emitted from a laser diode 91 passes through a polarization separation element 92, a collimator lens 93, a λ / 4 plate 97, and an objective lens 94, and then irradiates a DVD optical disk 98. The reflected light from the recording pits of the DVD optical disk 98 is linearly polarized by the λ / 4 plate 97 and then diffracted by the polarization separation element 92 and guided to the photodiode 96 for focus detection, track detection, and signal detection. Is done. In this optical pickup device, a polarization separation element manufactured by the alignment bonding method and apparatus of Example 1 or 2 is used as the polarization separation element 92.

When the information signal was reproduced from the DVD-ROM using the optical pickup device having the structure shown in FIG. 19, the signal equivalent to that of the conventional optical pickup device for DVD combining the beam splitter and λ / 4 plate bonded with the prism was used. An output can be obtained, and it has been confirmed that the optical pickup device of this example has a reproduction characteristic equivalent to that of a conventional optical pickup.
Further, in this optical pickup device, the polarization separation element 92 is smaller than the beam splitter to which the conventional prism is bonded, and thus is smaller than the conventional optical pickup device.

It is a schematic sectional drawing of the wafer-like joined substrate in which many polarization separation elements were formed. (A) is a plan view and a sectional view of the lower substrate, (b) is a plan view and a sectional view of the upper substrate, and (c) is a plan view and a sectional view of the protective substrate. (A) is a figure which shows the example of a shape of the alignment mark for devices formed on the organic birefringent film of a lower board | substrate, and the alignment mark for devices, (b) is the example of the shape of the alignment mark for devices formed in the upper board | substrate. FIG. 4C is a diagram showing an example of the shape of the outer alignment mark formed on the protective substrate. It is a schematic sectional drawing of the alignment joining apparatus which shows one Example of this invention. It is a figure which shows the alignment mark and crosshairs of the holding substrate on a monitor. (A) is a top view which shows the state which mounted the polyester film in the quartz glass wafer chuck. (B) is sectional drawing which shows the state which fixed the lower board | substrate to the quartz glass wafer chuck by vacuum suction. It is a figure which shows the state which is performing alignment of a holding | maintenance board | substrate and a lower board | substrate with the alignment joining apparatus of a structure shown in FIG. It is explanatory drawing of the alignment method at the time of aligning the external alignment mark of a lower board | substrate, and the external alignment mark of a holding substrate. It is a figure which shows the state which has bonded the holding | maintenance board | substrate and the lower board | substrate with the alignment joining apparatus of the structure shown in FIG. It is sectional drawing of a lower board | substrate with a holding board | substrate. It is a figure which shows the alignment mark and crosshairs of the upper board | substrate on a monitor. It is explanatory drawing of the alignment method at the time of aligning the alignment mark of a lower board | substrate, and the alignment mark of an upper board | substrate. It is a figure which shows the state which has adhere | attached the lower board | substrate with a holding substrate, and the upper board | substrate with the alignment joining apparatus of the structure shown in FIG. It is explanatory drawing of the process of cutting out an optical element from a joining board | substrate. It is the top view and sectional drawing of a quartz glass wafer chuck which provided the vacuum suction hole. It is a schematic sectional drawing of the alignment joining apparatus which shows another Example of this invention. It is a top view of the mask holder made from quartz glass which mounted | wore with the acrylic sheet which formed the board | substrate mounting window. It is a schematic block diagram which shows the structural example of the optical pick-up apparatus using the optical element (polarization separation element) which concerns on this invention. It is a schematic block diagram which shows another structural example of the optical pick-up apparatus using the optical element (polarization separation element) which concerns on this invention. It is a schematic sectional drawing of the mask aligner apparatus which shows an example of a prior art.

Explanation of symbols

1: Upper substrate 2: Lower substrate 3: Organic birefringent film 4: Protection substrate 5, 6, 7: Adhesive 8: Grating 9: Upper substrate alignment mark 10: Diffraction grating 11: Lower substrate alignment mark 12: Protection Substrate alignment mark 20, 20 ′: alignment bonding apparatus 20
21: Upper light irradiation device 22: Lower light irradiation device 23: Lower irradiation light reflection device 24: Alignment detection optical system 25, 25 ′: Quartz glass mask holder (substrate holder)
26.26 ′: Quartz glass wafer chuck (substrate chuck)
27: Stage 28: Stage moving device 28
29: Z-axis movement control device 30: Base 31: Base 32, 34: Vacuum exhaust port 33: Upper substrate suction groove 35: Lower substrate suction groove 36, 37: Polyester film 38: Zirconia cylinder 40: Bonded substrate 41: Dicing saw 42: Optical element 43: Vacuum suction hole 46: Zirconia spacer 47: Acrylic sheet

Claims (13)

  A substrate chuck portion made of an optically transparent planar member for fixing the substrate, a substrate holder portion made of an optically transparent planar member, a stage movable in each direction of X, Y, Z, and θ; Using an apparatus provided with a light irradiating part for irradiating and means for detecting alignment disposed on the substrate chuck part side, and provided with an alignment mark having unevenness formed by etching on the substrate chuck part. A step of setting a substrate, a step of setting an upper substrate having alignment marks having unevenness formed by etching on the substrate holder portion, a step of defining parallelism of the upper and lower substrates, and bonding the upper and lower substrates A step of defining the thickness of the adhesive layer on the surface to be aligned, a step of aligning the alignment marks of the upper and lower substrates, a step of applying an adhesive, and a step of spreading the adhesive Alignment joining method characterized by comprising the step of controlling the thickness of the adhesive, and curing the adhesive the adhesive is irradiated with light. The alignment bonding method according to claim 1,
An alignment joining method, wherein grooves or holes corresponding to at least a plurality of sizes are formed on a surface of a substrate holder portion made of an optically transparent flat member for fixing the upper substrate. In the alignment joining method according to claim 1 or 2,
An alignment bonding method, wherein grooves or holes corresponding to at least a plurality of sizes are formed on a surface of a substrate chuck portion made of an optically transparent flat member for fixing the lower substrate. In the alignment joining method according to any one of claims 1 to 3,
An alignment bonding method comprising: means for sealing a vacuum suction groove or hole other than the substrate suction portion on the surface of the substrate chuck portion and the substrate holder portion. In the alignment joining method according to any one of claims 1 to 4,
An alignment bonding method characterized in that a mask holder portion made of an optically transparent flat member for fixing the upper substrate is made of quartz glass. In the alignment joining method according to any one of claims 1 to 5,
An alignment bonding method, wherein a substrate chuck portion made of an optically transparent flat member for fixing the lower substrate is made of quartz glass. In the alignment joining method according to any one of claims 1 to 6,
A flat plate, cylinder or sphere having a known dimension is inserted between the substrate chuck portion for mounting and fixing the lower substrate and the substrate holder portion for fixing the upper substrate, and the parallelism between the alignment adhesive substrates and the thickness of the adhesive layer are set. An alignment joining method characterized by prescribing. In the alignment joining method according to any one of claims 1 to 7,
An alignment bonding method comprising aligning alignment marks on the upper and lower substrates from the substrate chuck side. In the alignment joining method according to any one of claims 1 to 7,
The alignment bonding method characterized in that light for curing and bonding the adhesive is irradiated alternately from the optically transparent substrate chuck side and substrate holder side.   A substrate chuck portion made of an optically transparent planar member for fixing the substrate, a substrate holder portion made of an optically transparent planar member, a stage movable in each direction of X, Y, Z, and θ; A lower substrate having an alignment mark having unevenness formed by etching is set on the substrate chuck portion. Means, means for setting an upper substrate provided with an alignment mark having irregularities formed by etching on the substrate holder portion, means for defining parallelism of the upper and lower substrates, and adhesion of surfaces for bonding the upper and lower substrates Means for defining the layer thickness, means for aligning the alignment marks of the upper and lower substrates, means for applying the adhesive, means for spreading the adhesive, and thickness of the adhesive 10. An alignment bonding apparatus comprising: means for controlling the temperature and means for curing and bonding the adhesive by irradiating light, and using the alignment bonding method according to claim 1. . In an optical element having a structure in which substrates are bonded with an adhesive,
An optical element manufactured using the alignment bonding method according to claim 1. In an optical element having a structure in which substrates are bonded with an adhesive,
An optical element produced by the alignment bonding apparatus according to claim 10. The optical element according to claim 11 or 12,
An optical element comprising a diffraction grating or a hologram on or between substrates and having a polarization separation function.

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