JP2009027318A - Method of manufacturing quartz oscillator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high-reliability quartz oscillator having stable oscillation characteristics with little variation in oscillation frequency by manufacturing a quartz oscillator with a high dimensional accuracy by forming and using finely and accurately formed alignment marks. <P>SOLUTION: The manufacturing method of the quartz oscillator includes a process of forming a predetermined pattern by photolithography method on both front and rear faces of a quartz substrate and a process of forming alignment marks for aligning the predetermined patterns. The alignment marks are formed by processing with laser light irradiated along an optical path from one flat plane of the quartz substrate toward the other flat plane opposite to the one flat plane through the inside of the quartz substrate. The laser light is irradiated on the quartz substrate along the optical path at right angles to the flat planes of the quartz substrate. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

The present invention relates to a manufacturing method for manufacturing a highly reliable crystal resonator that is used in a crystal oscillator, a gyro sensor, or the like and has stable oscillation characteristics with little variation in oscillation frequency.

  A crystal resonator used for a crystal oscillator or a gyro sensor is generally manufactured through the following processes. FIG. 6 is a diagram showing a general method for manufacturing a crystal resonator. As shown in FIG. 6, in general, a crystal resonator includes a crystal piece forming step (FIG. 6A) for forming a crystal piece 10 having a desired shape on the crystal substrate 100, and on the crystal piece 10 cut out from the crystal substrate 100. An electrode forming step for forming the electrode 20 for oscillating the crystal piece 10 (FIG. 6B), the crystal piece 10 on which the electrode 20 is formed is mounted on the package 30, and the crystal piece 10 is sealed by the lid member 40 It is manufactured by a packaging process (FIG. 6C). Among these manufacturing processes, the crystal piece forming process shown in FIG. 6A is a process for forming the outer shape of the crystal piece 10 that greatly affects the vibration characteristics of the crystal resonator, and is a very important process. It is. In other words, if the quartz piece 10 can be formed minutely and with high accuracy, a crystal resonator having excellent vibration characteristics and stable vibration characteristics can be manufactured.

  Conventionally, a cutting method, a sand blast method, an etching method, or the like has been used in the process of forming the crystal piece 10 on the crystal substrate 100. Among them, the etching method that chemically dissolves and processes the quartz substrate 100 is suitable for manufacturing a small and high-performance crystal resonator because it can be processed finely and with high precision. In many cases, the crystal piece 10 is formed using a method.

  Hereinafter, an example of a crystal piece forming process by a conventional etching method will be described. FIG. 7 is a diagram showing the first half of a crystal piece forming step by a conventional etching method. FIG. 8 is a view showing the latter half of the crystal piece forming step by the conventional etching method.

  First, as shown in FIG. 7A, mask layers 211 and 212 are respectively formed on both surfaces of the quartz substrate 110, and a resist layer 311 that is a photosensitive material is formed on the mask layer 211. A resist layer 312 which is a photosensitive material is formed on the mask layer 212.

  The mask layers 211 and 212 must be made of a material having corrosion resistance against an etching solution used in the etching process of the quartz crystal substrate 110 performed in a later process, and is generally gold (Au) or platinum (Pt). Such a metal material is often used for the mask layers 211 and 212.

  Next, as shown in FIG. 7B, exposure masks 410 and 420 are arranged in parallel to the quartz substrate 110 to perform exposure from both directions, and only predetermined portions of the resist layers 311 and 312 are irradiated with ultraviolet light (UV60). Sensitize.

  In this exposure step, the alignment mark m1 drawn on the exposure mask 410 and the alignment mark m2 drawn on the exposure mask 420 are aligned so that they are exposed to one plane of the quartz substrate 110. The pattern to be exposed and the pattern exposed to the other plane can be aligned.

However, as shown in FIG. 7B, a mask layer 211 made of Au or the like is provided between the alignment mark m1 of the exposure mask 410 and the alignment mark m2 of the exposure mask 420.
, 212 are arranged so as to block each other, so that it is not possible to align the alignment marks m1 and m2 while visually recognizing the alignment marks m1 and m2. Therefore, conventionally, the cameras 70 are arranged on both surfaces of the quartz substrate 110, and the alignment mark m1 and the alignment mark m2 imaged by the camera 70 are visually recognized and aligned.

  After the exposure as described above, the resist layers 311 and 312 are developed using a dedicated developer, and the mask layers 211 and 212 are etched using an etchant, as shown in FIG. Patterned resist layers 301 and 302 and mask layers 201 and 202 are formed.

  More generally, as shown in FIG. 8B, the resist layers 301 and 302 are peeled off so that the mask layers 201 and 202 are formed on both surfaces of the quartz substrate 110. It is not essential. In order to simplify the process, the process may proceed to the next process shown in FIG.

  Thereafter, as shown in FIG. 8C, etching is performed using the mask layer 201 and the mask layer 202 as a mask to form the quartz substrate 100 to which the patterns of the mask layers 201 and 202 are transferred.

  Finally, as shown in FIG. 8D, the mask layer 201 and the mask layer 202 are removed, and the quartz substrate 100 including the quartz piece 10 having a predetermined outer shape is completed. At this time, the portions where the alignment marks m1 and m2 are transferred remain on the quartz substrate 100 as the alignment mark marks 100a. FIG. 8D shows an AA cross section in FIG.

  In addition to this, a patterning method for aligning a mask layer patterned on one plane of a quartz substrate and an exposure mask arranged on the other plane side is also proposed as a crystal piece forming step (see, for example, Patent Document 1). ).

  FIG. 9 is a diagram showing the first half of a conventional patterning method for aligning a mask layer on one plane and an exposure mask on the other plane. FIG. 10 is a diagram showing the latter half of the conventional patterning method for aligning the mask layer on one plane and the exposure mask on the other plane.

  According to this patterning method, first, as shown in FIG. 9A, the mask layer 211 is formed on the entire surface of one plane of the quartz substrate 110, and the mask layer 213 is partially formed on the other plane of the quartz substrate 110. Form. Further, a resist layer 311 is formed on the mask layer 211.

  Next, as illustrated in FIG. 9B, the resist layer 311 is irradiated with ultraviolet light (UV60) through the exposure mask 410 to expose the resist layer 311. Note that an alignment mark m1 is drawn on the mask 410, and the pattern of the alignment mark m1 is exposed together with other patterns by this process.

  Next, as shown in FIG. 9C, the resist 311 is developed to form a resist layer 301 patterned in a shape to which the exposure mask 410 is transferred.

Then, using the resist layer 301 as a mask, the mask layer 211 is etched,
A mask layer 201 patterned in a predetermined shape is formed. Further, by removing the resist layer 301, a mask layer 201 patterned on one plane of the quartz crystal substrate 110 as shown in FIG. 9D is formed, and a mask that has not yet been patterned on the other plane. The state in which the layer 213 is formed is reached. In this step, an alignment mark M1 obtained by transferring the alignment mark m1 drawn on the exposure mask 410 is formed on the mask layer 201.

  Then, as shown in FIG. 10, a resist layer 312 is formed on the surface side where the mask layer 213 is formed, and the resist layer 312 is irradiated with ultraviolet light (UV60) through an exposure mask 420 to form a resist layer. The exposure of 312 is performed.

  In this conventional method, in this step, the alignment mark M1 formed on the mask layer 201 and the alignment mark m2 drawn on the exposure mask 420 are aligned while being visually recognized through the camera 70 disposed on one surface side. It is characterized by exposure. Since only one camera 70 is used, there is an advantage that a simple and inexpensive apparatus configuration can be obtained. Since the resist layer 312 is a transparent material or a semi-transparent material, the alignment mark m2 can be visually recognized through the resist layer 312.

  Further, a patterning method has been proposed in which the alignment marks of the exposure mask are arranged outside the outer shape of the quartz substrate to align the two exposure masks (see, for example, Patent Document 2).

  FIG. 11 is a diagram showing a patterning method in which the position of the alignment mark of a conventional exposure mask is positioned outside the outer shape of the quartz substrate for alignment.

  In this patterning method, as shown in FIG. 11, the quartz substrate 110 is formed smaller than the mask. Therefore, the alignment mark m1 drawn on the exposure mask 410 and the alignment mark m2 drawn on the exposure mask 420 are formed. Is located outside the outer shape of the quartz substrate 110.

  When the exposure masks 410 and 420 are disposed so as to sandwich the quartz crystal substrate 110 on which the mask layers 211 and 212 and the resist layers 311 and 312 are formed on both surfaces, the exposure masks 211 and 212 are usually opaque. The exposure mask 420 cannot be viewed from the mask 410 side, and similarly, the exposure mask 410 cannot be viewed from the exposure mask 420 side.

  However, in the case of FIG. 11, nothing exists between the alignment marks m1 and m2. Therefore, when viewed from the exposure mask 410 side with the camera 70, the alignment mark m2 of the exposure mask 420 behind the exposure mask 410 is visually recognized. It is possible. As a result, in this exposure method, it is possible to simultaneously expose both surfaces of the quartz substrate 110 with the UV 60 while aligning the alignment marks m1 and m2 with one camera 70.

Japanese Patent Laid-Open No. 9-43860 (second page, FIG. 2) JP 2004-7198 A (page 8, FIG. 1)

  In the case of the conventional exposure method (FIG. 7B) in which alignment is performed through the images of the two cameras 70, the difference in magnification, light quantity, lens aberration, and optical axis deviation of each camera 70 results in alignment accuracy. It had an adverse effect and it was difficult to achieve stable and accurate alignment. In the case of the maximum alignment accuracy, a positional deviation of several μm may occur.

Therefore, as shown in FIG. 8B, the mask layer 201 formed on one plane of the quartz substrate 110 and the mask layer 202 formed on the other plane are often formed in a misaligned state. As a result, as shown in FIG. 8D, the quartz substrate 100 that has been etched is formed into an irregular shape whose cross section is asymmetrical in the vertical direction.

  The quartz crystal piece 10 cut out from the quartz substrate 100 having such an irregular cross-sectional shape does not vibrate as designed. Therefore, the crystal resonator manufactured using the crystal piece 10 does not have the designed oscillation frequency as a matter of course. As a result, the conventional crystal resonator has low reliability in vibration characteristics.

  An exposure method (FIG. 10) for aligning the mask layer 201 patterned on one plane of the quartz substrate and the exposure mask 420 arranged on the other plane side, or aligning the alignment marks on the exposure mask with respect to the outer shape of the quartz substrate In the case of the exposure method (FIG. 11) in which the alignment is performed by placing the lens outside, only one camera 70 is used. Therefore, the adverse effects of the difference in magnification, light quantity, lens aberration, and optical axis deviation of the camera 70 as described above. Can be eliminated.

  However, the distance between the alignment mark M1 formed on the mask layer 201 shown in FIG. 10 and the alignment mark m2 on the exposure mask 420, and the alignment mark m1 on the exposure mask 410 and the alignment mark m2 on the exposure mask 420 shown in FIG. Is at least a distance greater than or equal to the thickness of the quartz substrate 110. Therefore, in order to align each alignment mark, a camera 70 having a deep focal depth capable of simultaneously viewing the two alignment marks is used. There is a need to.

  However, it is usually difficult to increase the magnification of the camera 70 as the depth of focus becomes deeper. For this reason, conventionally, as the thickness of the quartz substrate 110 increases, the camera 70 having a lower magnification must be used. It was. Therefore, it is difficult to perform alignment with high accuracy even using these exposure methods.

  As a result, even if these exposure methods shown in FIGS. 10 and 11 are used, there are many cases where a crystal piece 10 having an irregular cross section as shown in FIG. The crystal oscillator could not be manufactured.

  An object of the present invention is to provide a highly reliable crystal resonator having stable vibration characteristics with little variation in oscillation frequency.

In order to solve the above-described problems, a method for manufacturing a crystal resonator according to the present invention includes a step of forming a predetermined pattern on both front and back surfaces of a crystal substrate by a photolithography method, and an alignment used for aligning the predetermined pattern. In the method for manufacturing a crystal resonator having a step of forming a mark, the alignment mark is a laser beam irradiated in an optical path from one plane of the crystal substrate to the other plane facing through the inside of the crystal substrate. It is formed by the processing used.

  Further, it is desirable that the laser light is irradiated with an optical path that forms an angle substantially perpendicular to the plane of the quartz substrate.

  Furthermore, a mask layer made of a material that absorbs laser light and that is resistant to etching of the quartz substrate is formed on both sides of the quartz substrate, and this mask layer is processed to form alignment marks. Is desirable.

  Furthermore, it is desirable that the laser light is a femtosecond laser.

  Further, it is desirable that the quartz substrate is processed to form an alignment mark.

(Function)
The method for manufacturing a crystal resonator according to the present invention includes a predetermined pattern on both the front and back surfaces of a crystal substrate by a photolithography method, for example, an outer shape pattern of a crystal piece, a groove pattern formed in the crystal resonator, an electrode pattern of the crystal resonator, and the like. The present invention relates to a method for manufacturing a quartz crystal resonator having a step of forming.

  These patterns determine the outer shape of the crystal piece, the shape and position of the groove formed in the crystal resonator, the electrode shape and position of the crystal resonator, and the like. In particular, it is generally known that the external pattern of a crystal piece greatly affects the vibration characteristics of a crystal resonator. For the above reasons, the processing accuracy of these patterns is very important in stabilizing the characteristics of the crystal resonator.

  Usually, for example, when forming an external pattern on both the front and back sides of a quartz substrate, the external pattern on one plane (front surface) and the external pattern on the other plane (back surface) are aligned using a reference alignment mark. Therefore, it is very important how to accurately form the alignment mark as a reference.

  In the present invention, the reference alignment mark is formed by processing using laser light. Processing using a laser beam is generally called a laser ablation processing method, and is a method of processing a material with a laser beam focused with a very small beam diameter. Therefore, according to this processing method, it is possible to process with a very fine shape, and therefore it is possible to form an alignment mark with high definition and high accuracy.

  In the present invention, the laser light is irradiated from the one plane of the quartz substrate through the quartz substrate to the other opposing plane. The alignment mark is formed by laser processing on this optical path. Therefore, if the position and angle of the optical path of the laser beam are clearly known, the position of the alignment mark formed on the front and back surfaces of the quartz substrate can be accurately specified.

  In particular, if laser light is applied so that the optical path is at an angle substantially perpendicular to the plane of the quartz substrate, alignment marks can be formed at the same position on both the front and back surfaces.

  By using a femtosecond laser as the laser beam, processing at the nanometer level is possible, and an alignment mark with higher definition and higher accuracy can be formed.

  In the present invention, mask layers made of a material that absorbs laser light and has resistance to etching of the quartz substrate are formed on both the front and back surfaces of the quartz substrate. In general, since a material that absorbs laser light can be processed by laser, an alignment mark can be formed on the mask layer with the laser light. Further, since the mask layer on which the alignment mark is formed has resistance to etching of the quartz substrate, the quartz substrate can be etched using this mask layer as a mask. Thus, the mask layer of the present invention has an advantage that it can be used for both the alignment process and the etching process of the quartz substrate.

In addition, by using a femtosecond laser as the laser light, it is possible to process the quartz substrate itself that cannot be processed with the laser light. Therefore, it is also possible to form alignment marks on the quartz substrate. If the alignment mark is formed on the quartz substrate itself, the same alignment mark can be used for all processes such as the groove forming process and the electrode forming process in addition to the external processing of the crystal oscillator. More improved.

  According to the present invention, since a high-definition and high-precision alignment mark is formed and the crystal unit is processed based on the alignment mark, a crystal unit with good dimensional accuracy can be manufactured. It is possible to provide a highly reliable crystal resonator having stable vibration characteristics with little variation in oscillation frequency.

(First embodiment)
As shown in FIG. 6, the crystal resonator used in the crystal oscillator or the gyro sensor includes a crystal piece forming step (FIG. 6A) for forming a crystal piece 10 having a desired shape on the crystal substrate 100. An electrode forming step (FIG. 6B) for forming an electrode 20 for oscillating the crystal piece 10 on the crystal piece 10 cut out from FIG. 6, mounting the crystal piece 10 on which the electrode 20 is formed in a package 30, It is manufactured by a packaging process (FIG. 6C) in which the crystal piece 10 is sealed by the lid member 40.

  Among these manufacturing processes, the crystal piece forming process shown in FIG. 6A is a process for forming the outer shape of the crystal piece 10 that greatly affects the vibration characteristics of the crystal resonator, and is a very important process. It is.

  The crystal resonator manufacturing method according to the present invention is characterized in that, in this crystal piece forming step, the crystal piece 10 is formed finely and with high precision.

  FIG. 1 is a diagram showing a process of forming an alignment mark on a mask layer in the method for manufacturing a crystal resonator according to the present invention. FIG. 2 is a view showing an exposure process in the method for manufacturing a crystal resonator according to the present invention. FIG. 3 is a diagram showing steps after the development step of the mask layer in the method for manufacturing a crystal resonator according to the present invention.

  Hereinafter, a method for producing a crystal resonator according to the present invention will be described. First, mask layers 211 and 212 made of a material that absorbs laser light and has resistance to etching of the quartz substrate 110 are formed on both surfaces of the quartz substrate 110. In this embodiment, a chromium (Cr) film having a lower layer of 0.03 μm and a gold layer having a thickness of 0.1 μm are formed on both surfaces of a quartz substrate 110 having a polished surface of 160 μm by sputtering. Mask layers 211 and 212 having a laminated structure made of (Au) films were formed.

  Next, as shown in FIG. 1A, an angle substantially perpendicular to the plane of the crystal substrate 110 is directed from one plane side of the crystal substrate 110 on which the mask layers 211 and 212 are formed toward the mask layer 211. The laser beam 50 is irradiated. In the present embodiment, a carbon dioxide (CO 2) laser is used as the laser beam 50.

  Then, the mask layer 211 made of Au and Cr that absorbs the laser beam 50 is processed by the laser beam 50, and as a result, a mask layer 221 having a through hole is formed (FIG. 1B).

  Further, when the laser beam 50 is continuously irradiated, as shown in FIG. 1B, the laser beam 50 passes through the through hole formed in the mask layer 221 and reaches the mask layer 212 on the opposite plane. reach. As a result, the mask layer 212 made of Au and Cr that absorbs the laser beam 50 is processed by the laser beam 50, and a mask layer 222 having a through hole is formed on the opposite surface of the quartz substrate 110. (FIG. 1 (c)).

  The method for manufacturing a crystal resonator according to the present embodiment shown in the present embodiment is characterized in that the through holes formed in the mask layers 221 and 222 are used as the alignment marks M1 and M2. The through holes of the mask layers 221 and 222 formed by the laser beam 50 in this way are both about a few microns in size and very fine patterns, so that they are used as alignment marks M1 and M2. Very suitable for.

  Since these alignment marks M1 and M2 are processed by the laser beam 50, both are necessarily present on the optical path of the laser beam 50. Therefore, the positional relationship between the alignment marks M1 and M2 can be accurately specified if the position and angle of the optical path of the laser beam are known. If the positional relationship between the alignment marks M1 and M2 can be accurately specified, the alignment may be performed in consideration of the positional relationship, and highly accurate alignment is possible.

  In this embodiment, as described above, in this embodiment, the laser beam 50 is irradiated at an angle substantially perpendicular to the plane of the quartz substrate 110. Therefore, the optical path of the laser beam 50 forms an angle perpendicular to the plane of the quartz substrate 110.

  Therefore, the alignment marks M1 and M2 of the present embodiment on the optical path that forms an angle perpendicular to the plane of the quartz substrate 110 are formed at the same positions on both the front and back surfaces of the quartz substrate 110. Therefore, if the alignment is performed with reference to the alignment marks M1 and M2, the front and back patterns can be accurately aligned.

  In the present embodiment, the optical path of the laser beam 50 is described as being set at an angle substantially perpendicular to the quartz substrate 110. However, the substantially perpendicular angle is about 90 ° ± 1 ° with respect to the quartz substrate 110. Is an angle. Considering that the thickness of the quartz substrate of the present embodiment is 160 μm, if the optical path is tilted at an angle larger than this, the misalignment of the alignments M1 and M2 becomes several μm or more, which is conventionally performed. This is because the positional deviation in the manufacturing method is equal to or more than that.

  Therefore, in order to obtain the effect of the present invention, that is, the effect that the alignment marks M1 and M2 are less misaligned, it is desirable that the optical path of the laser light 50 be set at an angle of about 90 ° ± 1 ° with respect to the quartz substrate 110.

  Next, a photolithography process is performed using the alignment marks M1 and M2 thus formed. First, as shown in FIG. 2A, resist layers 311 and 312 made of a photosensitive material are formed on both surfaces of a quartz substrate 110 on which mask layers 221 and 222 are formed, and a mask layer on which an alignment mark M1 is formed. An exposure mask 410 is arranged so as to oppose 221 and the resist layer 311 is exposed with ultraviolet rays (UV60). In this embodiment, a positive resist from which exposed portions are removed is used as the resist layers 311 and 312. In this embodiment, since the mask layers 221 and 222 are made of a laminated film of Au and Cr that does not transmit UV60, there is no risk of exposing the resist layer 312 formed on the opposite plane. .

  The exposure mask 410 used in the present embodiment is drawn with an alignment mark m1 for alignment and an outer shape on one side of the crystal piece 10, and this exposure is performed while visually recognizing with the camera 70 in this step. The alignment mark m1 drawn on the mask 410 is aligned with the alignment mark M1 formed on the quartz substrate 110 for exposure.

At this time, the closer the distance between the alignment mark m1 and the alignment mark M1, the shallower the depth of focus, the higher magnification the camera 70 can be used. As a result, highly accurate alignment is possible. In particular, if exposure is performed with the exposure mask 410 in close contact with the resist layer 311 (generally referred to as contact exposure), the alignment mark m1 and the alignment mark M1 can be aligned with very high accuracy. . In the present invention, it is one of the advantages that a contact exposure method with high alignment accuracy can be used.

  Next, as shown in FIG. 2B, an exposure mask 420 is disposed so as to face the mask layer 222 on which the alignment mark M2 is formed, and the resist layer 312 is exposed with ultraviolet rays (UV60). Also in this step, since UV 60 is shielded by the mask layers 221 and 222 made of a laminated film of Au and Cr, there is no risk of exposing the resist layer 311 formed on the opposite plane.

  The exposure mask 420 used in the present embodiment is drawn with an alignment mark m2 for alignment and an outer shape on one side of the crystal piece 10. Therefore, in this step, exposure is performed by aligning the alignment mark m2 drawn on the exposure mask 420 with the alignment mark M2 formed on the quartz substrate 110 while visually recognizing with the camera 70.

  At this time, as in the process shown in FIG. 2A, the closer the distance between the alignment mark m2 and the alignment mark M2, the closer the alignment can be made. Therefore, if a method (contact exposure method) in which the exposure mask 420 is brought into close contact with the resist layer 312 is used, the alignment mark m2 and the alignment mark M2 can be aligned with very high accuracy.

  As described above, according to the present invention, the alignment mark m1 of the exposure mask 410 and the alignment mark M1 on the quartz substrate 110, and further the alignment mark m2 of the exposure mask 420 and the alignment mark M2 on the quartz substrate 110 are very highly accurate. It is aligned. Furthermore, in the present invention, the reference alignment mark M1 and alignment mark M2 are formed without misalignment by the process shown in FIG. 1, and as a result, in this embodiment, the alignment mark m1 and the exposure mask of the exposure mask 410 are formed. The alignment mark m2 420 is aligned with very high accuracy.

  In this embodiment, the exposure of one plane by the exposure mask 410 shown in FIG. 2A and the exposure of the other plane by the exposure mask 420 shown in FIG. 2B are performed as separate steps. The two cameras 70 may be used to align both sides at the same time and expose both sides at the same time. Even when both surfaces are aligned at the same time, the alignment is performed with a combination of the alignment mark m1 and the alignment mark M1, and a combination of the alignment mark m2 and the alignment mark M2, so that the alignment accuracy remains good. .

  Next, in the present embodiment, as shown in FIG. 3A, the exposed resist layers 311 and 312 are developed to form resist layers 301 and 302 in which the outer shape of the crystal piece 10 is patterned. In addition, FIG.3 (e) mentioned later has shown the AA cross section in Fig.6 (a).

  Further, as shown in FIG. 3B, the mask layers 221 and 222 are etched using the resist layers 301 and 302 as a mask to form mask layers 201 and 202 in which the outer shape of the crystal piece 10 is patterned. To do.

Further, as shown in FIG. 3C, when the resist layers 301 and 302 are removed with a stripping solution or the like, the mask layers 201 and 202 patterned on both surfaces of the quartz substrate 110 are formed.

  Thereafter, as shown in FIG. 3D, the quartz crystal substrate 100 is etched through the pattern of the mask layers 201 and 202 by using the mask layers 201 and 202 as a mask and etching the quartz substrate 110 with an etching solution such as hydrofluoric acid. Form. In the present embodiment, since the Au layer having corrosion resistance against the hydrofluoric acid that is the etching solution is used as the mask layers 201 and 202, the pattern of the mask layers 201 and 202 is broken during the etching process of the quartz substrate 110. It never happened.

  Finally, as shown in FIG. 3E, the mask layers 201 and 202 are removed, and the quartz substrate 100 on which the quartz piece 10 is formed is completed. The quartz crystal piece 10 formed on the quartz crystal substrate 100 thus formed is formed by the mask layers 201 and 202 aligned with very high accuracy, and as shown in FIG. However, the cross section is not an irregular shape with asymmetrical top and bottom, and the cross sectional shape as designed is symmetrical with respect to the top and bottom.

  The alignment mark mark 100a formed by etching remains in the place where the alignment marks M1 and M2 were originally formed on the quartz substrate 100 completed at this time. It does not adversely affect the characteristics of the crystal resonator manufactured using the piece 10.

  The quartz substrate 100 formed as described above is subjected to the normal process shown in FIG. 6, that is, electrode formation for forming the electrode 20 for oscillating the quartz piece 10 on the quartz piece 10 cut out from the quartz substrate 100. After the process (FIG. 6B), the crystal piece 10 on which the electrode 20 is formed is mounted on the package 30, and the crystal piece 10 is sealed by the lid member 40 (FIG. 6C), Completed as a vibrator.

  Since the crystal resonator 10 of the present invention manufactured in this way uses the crystal piece 10 having a cross-sectional shape as designed symmetrically in the vertical direction, it is possible to obtain good vibration characteristics as designed.

  Furthermore, according to the manufacturing method of the present invention, since the crystal piece 10 with high dimensional accuracy and little dimensional variation can be formed, a highly reliable crystal resonator having a stable oscillation frequency can be obtained.

(Second Embodiment)
FIG. 4 is a view showing a process of forming alignment marks on a quartz substrate in the method for producing a quartz resonator according to the present invention. In the second embodiment, fine and highly accurate alignment marks M1a and M1b are formed on the quartz substrate 110 itself. The method is shown below.

  First, as shown in FIG. 4 (a), a quartz substrate 110 having both surfaces polished is prepared, and from the front surface F to the back surface B of the quartz substrate 110, at an angle substantially perpendicular to the plane of the quartz substrate 110, A femtosecond laser beam 55 is irradiated.

  Since the femtosecond laser 55 is a long and short pulse laser and has a very high energy per unit time, it can be processed even with the quartz crystal substrate 110 that cannot be processed with a normal laser by focusing. Generally known.

In the present embodiment, as shown in FIG. 4A, the femtosecond laser 55 is condensed on the back surface B of the quartz substrate 110 by the condenser lens 80. Then, as shown in FIG. 4B, the back surface B of the quartz substrate 111 is processed to form an alignment mark M2a. The surface F of the quartz substrate 111 and the inside of the substrate are not processed because the femtosecond laser 55 is not condensed.

  Next, as shown in FIG. 4B, the condenser lens 80 was adjusted, and the femtosecond laser 55 was condensed on the surface F of the quartz substrate 110. Then, this time, the surface F is processed, and an alignment mark M1a is formed on the surface F of the quartz substrate 112 as shown in FIG.

  The alignment marks M1a and M2a formed as described above are both formed on the optical path of the femtosecond laser 55. In the second embodiment, the femtosecond laser light 55 is irradiated at an angle substantially perpendicular to the plane of the quartz substrate 110, and as a matter of course, the optical path is almost perpendicular to the plane of the quartz substrate 110. The angle is right. In view of these, the alignment marks M1a and M2a are formed at the same position on both the front and back surfaces of the quartz substrate 110. Therefore, if the alignment is performed with reference to the alignment marks M1a and M2a, the front and back patterns can be accurately aligned.

  Subsequent steps for manufacturing the crystal unit may be performed in substantially the same manner as the steps shown in the first embodiment.

That is, the step of aligning the alignment mark m1 on the exposure mask 410 and the alignment mark m2 on the exposure mask 420 with the reference alignment marks M1a and M2a and exposing the alignment mark M1a and M2a (FIG. 2), and further developing and etching the crystal piece 10 A step of forming the formed crystal substrate 100 (FIGS. 3 and 6A), and an electrode forming step of forming an electrode 20 for oscillating the crystal piece 10 on the crystal piece 10 (FIG. 6B). Further, it is a packaging step (FIG. 6C) in which the crystal piece 10 on which the electrode 20 is further formed is mounted on the package 30 and the crystal piece 10 is sealed with the lid member 40.

  Also according to the second embodiment, the obtained crystal piece 10 has a vertically symmetric cross-sectional shape as designed, and thus a crystal resonator manufactured using this has good vibration characteristics as designed.

  Furthermore, in the second embodiment as well, since the crystal piece 10 with high dimensional accuracy and little dimensional variation can be formed, a highly reliable crystal resonator with a stable oscillation frequency can be obtained.

  Since the alignment marks M1a and M2a obtained in this embodiment are directly carved on the quartz substrate 100, they can be used any number of times in other processes as long as the quartz piece 10 is not broken off from the quartz substrate 100. For example, the alignment marks M1a and M2a can be used for the following processes.

  FIG. 5 is a diagram showing an example of use of the quartz substrate with an alignment mark according to the present invention. As shown in FIG. 5A, if the electrode 20 is aligned with the alignment mark M1a as a reference, the electrode 20 can be wired with high accuracy with respect to the crystal piece 10, and as a result, vibration characteristics are obtained. Etc. can be stabilized.

  Further, as shown in FIG. 5B, it is possible to accurately form the groove 90 in a predetermined portion with reference to the alignment mark M1a. It is also possible to improve the vibration characteristics by forming the groove 90 with high accuracy.

It is the figure which showed the formation process of the alignment mark to the mask layer in the manufacturing method of the crystal oscillator of this invention. It is the figure which showed the exposure process in the manufacturing method of the crystal oscillator of this invention. It is the figure which showed the process after the development process of the mask layer in the manufacturing method of the crystal oscillator of this invention. It is the figure which showed the formation process of the alignment mark to the quartz substrate in the manufacturing method of the crystal oscillator of this invention. It is the figure which showed the usage example of the quartz substrate with an alignment mark of this invention. It is the figure which showed the manufacturing method of the general crystal oscillator. It is the figure which showed the first half of the crystal piece formation process by the conventional etching method. It is the figure which showed the second half of the crystal piece formation process by the conventional etching method. It is the figure which showed the first half of the patterning method which aligns the mask layer of the conventional one plane, and the exposure mask of the other plane. It is the figure which showed the latter half of the patterning method which aligns the mask layer of the conventional one plane, and the exposure mask of the other plane. It is the figure which showed the patterning method which positions and arranges the position of the alignment mark of the conventional exposure mask outside the external shape of a quartz substrate.

Explanation of symbols

10 crystal piece 20 electrode 30 package 40 lid member 50 laser 55 femtosecond laser 60 UV
70 Camera 80 Condenser lens 90 Groove 100, 110, 111, 112 Quartz substrate 100a Alignment mark mark 201, 202, 211, 212, 213, 221, 222 Mask layer 301, 302, 311, 312, 313 Resist layer 410, 420 Exposure mask

Claims (5)

In a method for manufacturing a crystal resonator, the method includes: forming a predetermined pattern on both front and back surfaces of a quartz substrate by a photolithography method; and forming an alignment mark used for aligning the predetermined pattern.
The alignment mark is formed by processing using a laser beam irradiated from one plane of the quartz substrate to the other plane facing the other plane through the inside of the quartz substrate. Child manufacturing method. The method of manufacturing a crystal resonator, wherein the laser light is irradiated through an optical path that forms an angle perpendicular to a plane of the crystal substrate. A mask layer made of a material that absorbs the laser beam and is resistant to etching of the quartz substrate is formed on both the front and back surfaces of the quartz substrate, and the mask layer is processed to form the alignment mark. The method for manufacturing a crystal resonator according to any one of claims 1 and 2, wherein: The method for manufacturing a crystal resonator according to any one of claims 1 to 3, wherein the laser beam is a femtosecond laser. The method for manufacturing a crystal unit according to claim 4, wherein the crystal substrate is processed to form the alignment mark.

Images