JP2006281328A - Method for manufacturing workpiece - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To polish a transparent substrate with highly accurate planar parallelism by eliminating an adhesive for joining between plural sheets of the transparent substrates to be machined or between the transparent substrate and a dummy substrate. <P>SOLUTION: The method for manufacturing a workpiece composed of laminated substrates includes a step for forming a plurality of recessed parts 12 on one main face of a first transparent substrate 11, a step for joining the first transparent substrate 11 with a second transparent substrate 13 by a direct joining method, a step for polishing each transparent substrate while measuring the thickness by emitting a laser to each recessed part 12 from the outside of each transparent substrate, a step for directly joining a third transparent substrate 14, to which the recessed part 12 is formed, to the first transparent substrate 11 and for polishing the third transparent substrate 13 while measuring the thickness by emitting a laser to the recessed part 12, and a step for manufacturing the workpiece by cutting the laminated substrate 16 manufactured by repeating the above steps. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method of manufacturing a workpiece having a desired outer shape and thickness from a transparent workpiece substrate such as quartz, or a laminated substrate on which workpiece substrates are laminated, and particularly, a workpiece having a remarkably thin thickness. Regarding the method.

In recent years, a variety of electronic devices have used quartz resonators as timing devices, and optical imaging devices have used optical low-pass filters with laminated thin plates such as quartz and lithium niobate. As the process proceeds, electronic components such as crystal resonators and optical low-pass filters mounted thereon are desired to be reduced in size and thickness.

  As described above, transparent substrates such as quartz and lithium niobate are used for these electronic components. These substrates, for example, in the case of a quartz base plate used for a quartz resonator, cut a lump of artificial crystalline lens grown by a hydrothermal synthesis method at an angle to obtain a desired vibration mode with respect to the crystal axis direction of the artificial crystalline lens, A circular or rectangular flat crystal element plate is formed by performing an outer shape process and a polishing process.

  In particular, when the desired vibration mode is the thickness shear vibration mode, the thickness polishing process is performed so as to excite at a desired frequency in order to determine the resonance frequency of the crystal base plate depending on the thickness of the crystal base plate. For example, in the thickness-shear vibration mode that is most frequently used as the vibration mode of a crystal resonator, the relationship between the thickness d (μm) and the fundamental resonance frequency f (MHz) can be expressed by f≈1670 / d. In accordance with this formula, a crystal element plate used in a crystal resonator or the like is processed to have a desired frequency by polishing the main surface of the element plate to reduce the thickness.

  An optical low-pass filter is generally prepared by first preparing a plurality of birefringent plates that have been polished to a desired outer shape and thickness, or a plurality of substrates such as a birefringent plate and a phase plate, and bonding the substrates together. It is formed by pasting each with an agent. Quartz or lithium niobate is used as the material of the substrate. The attenuation characteristic of the high-frequency signal by the optical low-pass filter is determined by the light beam separation width and the light beam separation pattern due to birefringence, and this separation width is proportional to the thickness of the substrate.

  Thus, for the manufacture of elements such as the quartz base plate and the birefringent plate constituting the electronic component as described above, the thickness polishing of the element is one of the important factors that influence the performance as an electronic component. . The following documents are disclosed about the manufacturing methods of workpieces, such as the above-mentioned quartz base plate and the substrate of an optical low pass filter.

JP 2004-90098 A Japanese Patent Laid-Open No. 7-50438

  In addition, the applicant has not found any prior art documents related to the present invention by the time of filing of the present application other than the prior art documents specified by the prior art document information described above.

  In the thickness polishing process using the double-side polishing apparatus as disclosed in Patent Document 1, as a means for measuring the thickness of each substrate to be processed, a magnescale or the like is attached to the polishing apparatus, and the thickness of the substrate to be processed Means for measuring and controlling the dimensions with high accuracy are used. However, the thickness polishing process using such a double-side polishing apparatus has a limit of processing up to several tens of μm per sheet. When processing further thinly, a method is also used in which a dummy substrate having a thickness larger than that of the substrate to be processed is attached to the substrate to be processed and polished. In this method, generally, the substrate to be processed and the dummy substrate are used. Adhesives are used to attach to the substrate, and as the substrate to be processed becomes thinner, the planar parallelism of the bonded substrates to be processed is adversely affected by the elasticity of the adhesive and uneven distribution of the coating. There is a risk.

The present invention has been made in view of the above-described problems of the prior art, and is formed from a laminated substrate obtained by laminating a plurality of wafer-like transparent substrates obtained by integrally arranging a plurality of workpieces in a matrix shape. In the manufacturing method of the workpiece to be performed,
A step of forming a plurality of recesses of arbitrary depth outside the region where the workpiece is formed on one main surface of the first transparent substrate whose surface is processed in parallel with the plane;
Bonding one main surface of the first transparent substrate in which the concave portion is formed and one main surface of the second transparent substrate by a direct bonding method;
While irradiating the second transparent substrate above the recess with laser and measuring the thickness of the second transparent substrate, the second transparent substrate is moved from the other main surface side of the second transparent substrate to a desired thickness. Polishing process;
The first transparent substrate is desired from the other main surface side of the first transparent substrate while the concave portion is irradiated with laser from the other main surface side of the first transparent substrate and the thickness of the first transparent substrate is measured. Polishing to a thickness of
On the other main surface of the first transparent substrate or the second transparent substrate, a third transparent substrate having the same form as the first transparent substrate in which the concave portion is formed is disposed, and the first transparent substrate or the first transparent substrate A step of directly joining the other main surface of the second transparent substrate and one main surface of the third transparent substrate on which the concave portion is formed; and a third transparent substrate on the concave portion formed on the third transparent substrate. Laser irradiation is performed from the main surface opposite to the bonding main surface of the substrate, and the third transparent substrate is measured from the other main surface side of the first transparent substrate while measuring the thickness of the third transparent substrate. Polishing to thickness,
Repeating a step similar to the step of forming the third transparent substrate to form a laminated substrate with a desired number of laminated transparent substrates;
And cutting the laminated substrate into a desired workpiece outer shape to obtain individual workpieces.

Further, in a manufacturing method of a workpiece formed from a wafer-like transparent substrate obtained by integrally arranging a plurality of workpieces in a matrix shape,
A step of forming a plurality of recesses of a predetermined depth in a region where the transparent substrate is contact-bonded in a step described later, on one main surface of the glass substrate whose surface is processed in parallel with the plane;
A step of directly bonding one main surface of the glass substrate on which the concave portion is formed and one main surface of the transparent substrate by a direct bonding method;
A process of polishing the transparent substrate from the other main surface side of the transparent substrate to a desired thickness while irradiating a laser on the transparent substrate above the recess and measuring the thickness of the transparent substrate;
A step of cutting a transparent substrate that has been subjected to polishing and processed to a desired thickness into an outer shape of a desired workpiece;
A method of manufacturing a workpiece, comprising: separating a separated transparent substrate and a glass substrate and obtaining a workpiece having a desired outer shape and thickness.

  By using such a method for manufacturing a workpiece, an adhesive is used for bonding between a plurality of transparent substrates, which are substrates to be processed, or between a transparent substrate and a dummy substrate (corresponding to a glass substrate in the present invention). Therefore, it is possible to polish the transparent substrate with higher accuracy of plane parallelism than the conventional method. In addition, according to the present invention, even when a direct bonding method is used for bonding between a plurality of transparent substrates or between a transparent substrate and a dummy substrate, it is possible to measure the thickness of each transparent substrate with laser light. Further, since a glass substrate is used as the dummy substrate, a relatively thick dummy substrate can be formed, warping is less likely to occur during polishing, and it is less expensive than a dummy substrate using silicon or the like.

  Therefore, by using the processing method according to the present invention, it is possible to provide a workpiece that is inexpensive, has high productivity, and has high external shape accuracy such as plane parallelism.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a partial process diagram illustrating an outline of a method for manufacturing a workpiece according to the present invention by illustrating a manufacturing process of an optical filter element. FIG. 2 is a partial process diagram illustrating an outline of another manufacturing method of the workpiece according to the present invention by exemplifying the manufacturing process of the quartz base plate. FIG. 3 is a perspective view showing one embodiment of the transparent substrate and the glass substrate in the step (c) disclosed in FIG.
In FIGS. 1 and 2, a part of the structure is not shown for clarity of explanation, and some dimensions are exaggerated.

  That is, as a manufacturing process of the optical filter element according to the present invention, first, in FIG. 1A, as a substrate to be processed, a first transparent substrate made of quartz having a function as a birefringent plate whose surface is processed in parallel plane. 11 on one main surface of the first transparent substrate 11, and within the region where the second transparent substrate 13 contacts and joins in a step described later and outside the region where the optical filter element is formed. A plurality of recesses 12 having a depth of 5 are formed. The thickness of the first transparent substrate 11 at the time of this step is formed sufficiently thicker than the thickness at the final processing end form. In addition, as long as it is in the area | region where the 2nd transparent substrate 13 contacts and joins, the formation location of the recessed part 12 will not be limited, but it forms in the area | region which corresponds to the optical filter element formation area in the 1st transparent substrate 11 as much as possible. It is desirable to do. Note that the shape of the opening surface of the recess 12 may be rectangular or circular.

  Next, in FIG. 1B, a second transparent substrate 13 made of quartz having a function as a birefringent plate whose surface is processed in parallel with the surface and having the same outer shape as the first transparent substrate is used. Are prepared, and one main surface of the first transparent substrate 11 in which the recess 12 is formed and one main surface of the second transparent substrate 13 are bonded by a direct bonding method. As a method of direct bonding, by optically polishing the bonding-side main surfaces of the first transparent substrate 11 and the second transparent substrate 13 subjected to the outer shape processing, and further plasma-treating the bonding main surfaces to make them hydrophilic. The main surfaces of one of the first transparent substrate 11 and the second transparent substrate 13 are easily temporarily joined at room temperature, and then subjected to heat treatment for main joining.

  Next, in FIG. 1C, the second transparent substrate 13 on the opening surface of the recess 12 is irradiated with laser light, and the thickness of the second transparent substrate 13 is measured. The second transparent substrate 13 is polished from the other main surface side to a desired thickness. Further, the concave portion 12 is irradiated with laser from the other main surface side of the first transparent substrate 11 to measure the thickness of the first transparent substrate 11, and the first transparent substrate 11 is attached to the first transparent substrate 11. Polishing is performed from the other main surface side to a desired thickness. In the case of a transparent body, by irradiating the transparent body with laser light, the thickness of the portion irradiated with the laser light can be measured due to the difference between the reflected light from one surface and the reflected light from the other surface, When the first transparent substrate 11 and the second transparent substrate 13 are joined by direct joining, the joining interface is joined at the atomic level, so that the laser beam is not reflected by the joining interface, and the laser beam is used. Thickness measurement was impossible. However, since the air gap is formed between the first transparent substrate 11 and the second transparent substrate 13 by forming the recess 12 in the main surface of the first transparent substrate 11 on the joining side, the irradiation is performed. The laser beam can be reflected on the bonding-side surface of the second transparent substrate 13 corresponding to the opening surface of the recess 12 and the inner wall surface of the recess 12, and therefore the first transparent substrate 11 and the second transparent substrate similar to the first transparent substrate 11. The thickness dimension of 13 can be accurately measured.

  Furthermore, since a plurality of recesses 12 are formed on the bonding main surface of the first transparent substrate, thickness dimension data at the position where each recess 12 is formed is acquired. Since this shows that there is uneven polishing, it is possible to make the thickness of the entire transparent substrate uniform by performing polishing to correct the thickness.

  Next, in FIG. 1 (d), on the other main surface of the first transparent substrate 11, a crystal having a function as a birefringent plate having a surface parallel processed as a substrate to be processed and a recess 12 is formed. A third transparent substrate 14 having the same form as the formed first transparent substrate 11 is disposed, and the other main surface of the first transparent substrate 11 and a recess 15 of the third transparent substrate are formed. The main surface is directly joined. The direct bonding method is the same as the method used for the direct bonding between the first transparent substrate 11 and the second transparent substrate 13 described above.

  Next, in FIG. 1E, the third transparent substrate 14 newly joined in the step shown in FIG. 1D is sent to the recess 15 from the other main surface side of the third transparent substrate 14. Irradiating and measuring the thickness of the third transparent substrate 14, and polishing the thickness from the main surface side opposite to the direct bonding surface with the first transparent substrate 11 to a desired thickness.

  Next, by repeating the steps shown in FIGS. 1D and 1E, a laminated substrate 16 in which birefringent plates having a desired number of layers are laminated and directly joined as shown in FIG. 1F is obtained. Form. When the desired number of layers is two, the above steps C, D and E are not performed.

  Next, in FIG. 1 (g), an antireflection film is formed on the outermost main surface of the laminated substrate 16, and the laminated substrate is cut into an optical filter element forming region and other regions by the cutting line shown in the figure. Separately, individual optical low-pass filters 17 as shown in FIG.

  In the first embodiment, one main surface in which the concave portion 15 of the transparent substrate including the third transparent substrate 14 is formed on the other main surface side of the first transparent substrate 11 is laminated and bonded by a direct bonding method. Although the embodiment has been disclosed, the present invention is not limited to this. For example, one of the main surfaces of the second transparent substrate 13 on which the concave portion 15 of the transparent substrate including the third transparent substrate 14 is formed. Alternatively, the main surface may be laminated and bonded by a direct bonding method.

  In the first embodiment, the transparent substrate constituting the laminated base 16 is made of quartz. However, it is not necessary to form all the transparent substrates with quartz, and niobium is used in accordance with the function of the desired optical filter. A birefringent plate formed of another optical crystal such as lithium acid may be used.

An embodiment of a form different from the first embodiment will be disclosed.
As a manufacturing process of the quartz base plate in the present invention, in FIG. 2A, a glass substrate 21 whose surface is plane-parallel processed is prepared as a dummy substrate. The glass substrate 21 is formed sufficiently thick as compared with a transparent substrate 23 described later. In this embodiment, the outer shape of the glass substrate is a disk shape, but the present invention is not limited to this shape, and may be a polygonal shape such as a rectangular shape. Further, compared to the case where a silicon substrate or the like is used as a dummy substrate, the thickness can be increased and the cost is low.

  Next, in the step of FIG. 2B, a concave portion having a predetermined depth is formed in a region where the transparent substrate 23 is contact-bonded in a later-described step on one main surface of the glass substrate 21 prepared in the previous step. A plurality of 22 are formed. The position where the concave portion 22 is formed is not limited as long as it is within the region where the transparent substrate 23 is contact-bonded. However, it is desirable to form the concave portion 22 in the region outside the workpiece forming region as much as possible. The shape of the opening surface of the recess 22 may be rectangular or circular.

  Next, in the step of FIG. 2C, a transparent substrate 23 having the same outer shape and the same surface area as the glass substrate 21 is prepared as a substrate to be processed, and one main surface of the glass substrate 21 on which the concave portion 22 is formed. The one main surface of the transparent substrate 23 is bonded by a direct bonding method. As a technique of direct bonding, the glass substrate 21 and the transparent substrate are formed by precisely polishing the bonding main surfaces of the glass substrate 21 and the transparent substrate 23 subjected to the outer shape processing, and further hydrophilizing the bonding main surfaces by performing plasma treatment. One main surfaces of 23 are easily temporarily bonded to each other, and then heat-treated to perform main bonding (atomic level bonding between main surfaces). If the bonding main surface is larger than a certain area, sufficient bonding strength can be obtained only by temporary bonding without performing heat treatment and main bonding. Note that quartz is used as the material of the transparent substrate 23.

  Next, in the step of FIG. 2D, the transparent substrate 23 portion on the opening surface of the recess 22 is irradiated with laser light, and the thickness of the transparent substrate 23 is measured, while the other main surface side of the transparent substrate 23 is measured. The transparent substrate 23 is polished to a desired thickness. In the case of a transparent body, by irradiating the transparent body with laser light, the thickness of the portion irradiated with the laser light can be measured due to the difference between the reflected light from one surface and the reflected light from the other surface, When the transparent substrate 23 and the glass substrate 21 are bonded by direct bonding, since the bonding interface is bonded at the atomic level, the laser beam is not reflected at the bonding interface, and the thickness measurement using the laser beam is impossible. there were. However, since the air gap is formed between the transparent substrate 23 and the glass substrate 21 by forming the concave portion 22 on the bonding main surface of the glass substrate 21, the irradiated laser light is transparent on the opening surface of the concave portion 22. It can reflect on the bonding side surface of the board | substrate 23, Therefore The thickness dimension of the transparent substrate 23 can be measured accurately. The transparent substrate 23 is polished from the main surface side opposite to the main surface to be bonded to the glass substrate 21 in accordance with the data obtained by the thickness measurement by the laser beam, so that the transparent substrate 23 has a desired thickness. Process.

  Next, in the step of FIG. 2 (e), the transparent substrate 23 that has been polished and processed to a desired thickness is cut into a desired external shape of the crystal base plate (cut line A in FIG. 2 (e)). In FIG. 3, the transparent substrate 23 is cut by a dotted line. As means for cutting, dicing or the like is used to cut all or part of the glass substrate 21 in the thickness direction.

  Next, in the process of FIG. 2F, the transparent substrate 23 and the glass substrate 21 that have been separated into pieces are separated, and a plurality of quartz base plates 24 having a desired outer shape and thickness are obtained simultaneously. Separation of the transparent substrate 23 and the glass substrate 21 can be performed by reducing the bonding strength because stress is applied to the bonded portion in the cutting process in the previous process. Or, when there is a difference between the thermal expansion coefficient of the transparent substrate 23 and the thermal expansion coefficient of the glass substrate 21, by fixing the transparent substrate 23 with an adhesive tape or the like after the cutting step and heating it, A method is used in which stress is applied to the joint portion and separation is easily performed.

  In addition, this invention is not limited to the above-mentioned embodiment, A various change, improvement, etc. are possible in the range which does not deviate from the summary of this invention. For example, in Example 2, a method for manufacturing a quartz base plate has been disclosed, but the present invention is not limited to quartz as the material of the transparent substrate, and other transparent piezoelectric materials such as lithium niobate may be used.

FIG. 1 is a partial process diagram showing an outline of a method for manufacturing a workpiece in the present invention. FIG. 2 is a partial process diagram showing an outline of another method of manufacturing a workpiece in the present invention. FIG. 3 is a perspective view showing one embodiment of the transparent substrate and the dummy substrate in step (c) of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 ... 1st transparent substrate 12 ... Recessed part 13 ... 2nd transparent substrate 14 ... 3rd transparent substrate 15 ... Recessed part 16 ... Laminated substrate 17 ... Workpiece (Optical filter element)
21 ... Glass substrate 22 ... Recess 23 ... Transparent substrate 24 ... Workpiece (crystal base plate)

Claims (4)

In a manufacturing method of a workpiece formed from a laminated substrate obtained by laminating a plurality of wafer-like transparent substrates obtained by integrally arranging a plurality of workpieces in a matrix shape,
A step of forming a plurality of recesses of arbitrary depth outside the region where the workpiece is formed on one main surface of the first transparent substrate whose surface is processed in parallel with the plane;
Bonding one main surface of the first transparent substrate in which the concave portion is formed and one main surface of the second transparent substrate by a direct bonding method;
While irradiating the second transparent substrate on the concave portion with a laser and measuring the thickness of the second transparent substrate, the second transparent substrate is placed on the other main surface side of the second transparent substrate. Polishing to a desired thickness from,
The concave portion is irradiated with laser from the other main surface side of the first transparent substrate, and the thickness of the first transparent substrate is measured, and the first transparent substrate is moved to the other side of the first transparent substrate. Polishing to the desired thickness from the main surface side;
On the other main surface of the first transparent substrate or the second transparent substrate, a third transparent substrate having the same shape as the first transparent substrate in which the recess is formed is disposed, and the first transparent substrate A step of directly joining the other main surface of the transparent substrate or the second transparent substrate and one main surface of the third transparent substrate in which the recess is formed; and a recess formed in the third transparent substrate. Further, the third transparent substrate is irradiated with a laser from a main surface opposite to the bonding main surface of the third transparent substrate, and the thickness of the third transparent substrate is measured, and the third transparent substrate is moved to the first transparent substrate. Polishing to the desired thickness from the other main surface side of the substrate;
Repeating a step similar to the step of forming the third transparent substrate to form a laminated substrate with a desired number of laminated transparent substrates;
Cutting the laminated substrate into a desired workpiece outer shape;
A method of manufacturing a workpiece, comprising: In a manufacturing method of a workpiece formed from a wafer-like transparent substrate obtained by integrally arranging a plurality of workpieces in a matrix,
A step of forming a plurality of recesses of a predetermined depth in a region where the transparent substrate is contact-bonded in the next step, on one main surface of the glass substrate whose surface is processed in parallel with the plane;
Bonding one main surface of the glass substrate on which the concave portion is formed and one main surface of the transparent substrate by a direct bonding method;
Irradiating the transparent substrate on the concave portion with a laser, and measuring the thickness of the transparent substrate while polishing from the other main surface side of the transparent substrate to a desired thickness; and
Cutting the transparent substrate that has been polished and processed to a desired thickness into a desired workpiece outer shape; and
A process for separating the separated transparent substrate and the glass substrate.   2. The method of manufacturing a workpiece according to claim 1, wherein at least one of the transparent substrates is made of quartz.   The method of manufacturing a workpiece according to claim 2, wherein the material of the transparent substrate is quartz.

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