JP4960060B2 - Quartz diaphragm and manufacturing method thereof - Google Patents

Description

  The present invention relates to a crystal resonator which is one of electronic components, a crystal diaphragm mounted in a crystal oscillator, and a manufacturing method thereof.

  At present, crystal devices such as crystal resonators and crystal oscillators are widely used in electronic devices such as mobile phones and digital home appliances as reference signal generation sources and timing devices. Inside these crystal devices, as shown in FIG. 7, excitation electrodes 702 and excitation electrodes 702 are formed on both front and back main surfaces of a plate-like crystal piece 701 whose outer peripheral shape is processed into a rectangular shape or a circular shape. The external connection electrode 703 for electrically connecting the quartz electrode to the crystal pad connecting electrode pad formed in the container body of the crystal device, and the extraction electrode electrically connecting the excitation electrode 702 and the external connection electrode 703 A quartz diaphragm 700 on which 704 is formed is mounted. The quartz crystal device 701 excites the quartz piece 701 in a predetermined vibration mode and frequency by the piezoelectric effect by applying a variable voltage from the outside to the quartz piece 701 via the excitation electrode 702 constituting the quartz diaphragm 700. The phenomenon that occurs is used.

  Conventionally, as a method of manufacturing such a crystal diaphragm 700, an artificial crystalline lens grown by a hydrothermal synthesis method is cut into a wafer shape at a predetermined cut angle, and this wafer-shaped crystalline lens is further cut, polished, etched, etc. By repeatedly performing the outer shape processing, a crystal piece 701 having a desired thickness, a substantially flat plate shape, and a circular or square outer peripheral shape of the main surface is obtained, and a vapor deposition method, a sputtering method, etc. A method of forming the excitation electrode 702, the external connection electrode 703, and the extraction electrode 704 of the above-described form made of a metal such as Cr and Au is used.

The above-described quartz diaphragm and the manufacturing method thereof are disclosed in the following prior art documents.
Edited by the Japan Quartz Device Association Technical Committee, “Explanation and Application of Quartz Devices”, published by the Japan Quartz Device Industry Association, published in March 2002, p. 3-13. JP 2001-230235 A JP 11-88104 A Japanese Patent Laid-Open No. 10-51265

  In addition, the applicant did not find 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.

However, in a conventional flat plate-shaped rectangular crystal plate, for example, in a crystal device in which the crystal plate is mounted in a container body, when sudden impact force is applied to the crystal device from the outside, such as dropping, the crystal device The internal crystal diaphragm is momentarily deformed by the external force. In particular, as a form in which a crystal diaphragm is mounted in a container, an external connection electrode is formed only on one short side edge of the crystal diaphragm, and the external connection electrode and an electrode pad formed in the container are fixed. conducting morphology (so-called cantilever type), the short side edge of one of the anchored quartz plate becomes a fulcrum, bending the quartz plate is a long side direction, not fixed quartz plate other of The short side end position is greatly displaced. Due to this phenomenon, the quartz diaphragm comes into contact with the container body, the lid, etc., and in the worst case, the quartz diaphragm may be broken by the impact of the contact. This defect may become more prominent as the frequency of the quartz diaphragm increases (thinner).

  In addition, in the conventional method of manufacturing a crystal piece by performing external processing such as cutting or polishing on an artificial lens, it is necessary to discard more than half of the weight of the artificial lens as cutting waste or polishing waste. The acquisition efficiency of the crystal piece formed from the crystalline lens becomes very low. In particular, when a crystal piece having a relatively complicated shape that is not flat like the present invention is formed by a conventional method, more cutting waste and polishing waste may be generated, and the acquisition efficiency may be further reduced. There is. Further, in recent years, with the progress of miniaturization and higher frequency of quartz devices, there is a demand for miniaturization and thinning of the quartz pieces constituting the quartz diaphragm mounted in the quartz device. As the crystal pieces of the present invention are made smaller and thinner, the conventional manufacturing means must be highly accurate and the number of processing steps such as cutting and polishing must be increased. Since a large number of mechanical equipments are required for this purpose, there is a problem that manufacturing time and cost are greatly increased.

  An object of the present invention is to provide a quartz crystal plate having a structure that significantly reduces the amount of deformation of the structure caused by the external force even when an external force is applied, and a quartz crystal piece that forms the quartz crystal plate in the conventional manner. By using a manufacturing method that can easily cope with downsizing and thinning of a crystal piece without applying any mechanical external processing means, a crystal diaphragm having a good impact resistance is further obtained. An object of the present invention is to provide a method that can be easily manufactured at low cost.

The quartz crystal plate according to the present invention is made to solve the above-described problems, and excitation electrodes are formed on both the front and back main surfaces of a thin plate-like crystal piece having a substantially rectangular main surface outline. In the quartz crystal plate in which the external connection electrodes electrically connected to the respective excitation electrodes are formed on the short side edge portion of the quartz crystal piece, the long side direction in the quartz piece constituting the quartz crystal plate The step part of the form bent only in one thickness direction is formed only in the two side edge parts of these sides, and the whole crystal piece including the step part is formed with a seamless integrated structure. It is a crystal diaphragm characterized by.

  Further, in the crystal diaphragm described in the preceding paragraph, an external connection electrode is provided only on one short side edge portion of two short sides of the crystal diaphragm.

  Further, in the step portion described in paragraph (0009), the step portion is inclined at an angle of less than 90 ° toward the bent direction.

  Furthermore, in the quartz diaphragm described in paragraph (0009), the quartz diaphragm is characterized in that the height dimension t of the quartz diaphragm is smaller than the value obtained by doubling the thickness dimension t1 of the quartz piece.

The method of manufacturing a quartz crystal plate according to the present invention is made in order to solve the above-described problems. Excitation electrodes are respectively provided on both the front and back main surfaces of a thin plate-like crystal piece having a substantially rectangular main surface outline. In the manufacturing method of the quartz crystal plate in which the external connection electrodes electrically connected to the respective excitation electrodes are formed on the short edge of the quartz piece, the vapor phase crystal growth apparatus is used to produce the vapor phase crystal. A thin plate-like crystal piece with a stepped portion is formed at a predetermined position in the crystal growth chamber constituting the growth apparatus, only at two edge portions in the desired long side direction, and bent in only one thickness direction over the entire length of these sides. A quartz film forming substrate in which a plurality of convex portions each having a stepped surface having the same shape as the main surface shape formed on the top surface is formed on one main surface in a matrix at a predetermined interval. The top surface of each convex part is directed upward or toward the crystal source gas inlet. Placing in a form and a crystal element on the surface of the quartz deposition substrate by vapor phase crystal growth method, the excitation region of the crystal blank is epitaxially grown at a predetermined crystal orientation to a thickness of excited at the desired frequency Removing the quartz film forming substrate on which the crystal piece has grown on the surface from the crystal growth chamber and separating the crystal piece formed on the top surface of each convex portion from the top surface of each convex portion; And a step of forming an excitation electrode, an external connection electrode, and an extraction electrode for electrically connecting the excitation electrode and the external connection electrode on the surface of the crystal piece. Is the method.

With the quartz crystal plate according to the present invention, only two edge portions in the long side direction of the crystal piece constituting the quartz crystal plate are formed with a stepped portion that is bent in only one thickness direction over the entire length of these sides. Therefore, even if this step part acts as a beam in the length direction of the quartz diaphragm, and external force such as sudden impact force due to dropping etc. is applied to the quartz diaphragm, the crystal vibration is caused by the beam action of this step part. it is possible to suppress deformation such as a plate bends in the long side direction. Therefore, when the crystal diaphragm is deformed by an external force, it is possible to prevent a problem that the crystal diaphragm is broken due to contact with a container body or a lid body on which the crystal diaphragm is mounted. In particular, the effect of the stepped portion becomes more prominent as the quartz diaphragm becomes higher in frequency (thinner).

  In addition, since the stepped crystal diaphragm according to the present invention is formed by the manufacturing method as described above, there is no special process for forming the step portion on the crystal diaphragm, and the manufacturing of the crystal piece constituting the crystal diaphragm is performed. The step portion can be formed in an integrated structure during the process and simultaneously with the formation of the crystal piece. Therefore, even if the step portion is formed on the quartz diaphragm, the manufacturing time does not increase and the manufacturing cost does not increase. Further, in the method of manufacturing a quartz crystal plate according to the present invention, the quartz crystal plate constituting the quartz crystal plate can be easily manufactured as an integrated structure with no joint between the whole quartz piece including the stepped portion. There is no weak structural part, and it has excellent impact resistance.

  Furthermore, since it is a method of manufacturing a crystal piece directly on a single crystal substrate by using a vapor phase crystal growth method, in order to manufacture a crystal piece as compared with a method of manufacturing a crystal piece by using a conventional cutting polishing or the like. Therefore, it is possible to easily manufacture a crystal piece constituting a crystal diaphragm with a stepped portion even when the crystal piece is downsized and thinned. In addition, since no mechanical processing such as cutting is applied to the crystal piece during the manufacture of the crystal piece, chipping and chipping of the outer peripheral edge due to the crystal piece manufacturing means are almost eliminated, and the crystal piece is vibrated. The characteristics and drive characteristics are not adversely affected by chipping or chipping. Furthermore, chipping and chipping that are indeterminate and indefinite do not occur in each crystal piece. Become.

  Therefore, according to the present invention, when a quartz crystal plate whose deformation is remarkably reduced even when an external force is applied and the quartz piece constituting the quartz plate are manufactured, a mechanical outer shape processing is conventionally performed on the quartz piece. By using a manufacturing method that can easily cope with the miniaturization and thinning of the quartz piece without applying any means, it is possible to produce a quartz plate with good impact resistance and to make the quartz plate easily and inexpensively. This provides an effect of providing a method that can be manufactured.

Embodiments of a quartz crystal plate and a method for manufacturing the same according to the present invention will be described below with reference to the drawings.
1A and 1B show the appearance of a quartz crystal diaphragm according to the present invention. FIG. 1A is a plan view of the quartz diaphragm as viewed from above one main surface corresponding to the bending direction of a stepped portion, and FIG. It is a schematic sectional drawing at the time of cut | disconnecting by the virtual cutting line AA 'of description. FIG. 2 is a partial enlarged cross-sectional view showing an enlarged portion of the dotted circle A shown in FIG. FIG. 3 is an external perspective view showing the crystal diaphragm shown in FIGS. 1 and 2.

  Further, FIG. 4 is an explanatory view showing a vapor phase crystal growth apparatus used in the method of manufacturing a quartz crystal plate according to the present invention. FIG. 5 shows a part of one embodiment of a crystal film forming substrate disposed on a support in the crystal growth chamber constituting the vapor phase crystal growth apparatus shown in FIG. 4 from above the main surface on the exposed side of the crystal growth chamber. It is the partial external appearance perspective view shown. FIG. 6 is a process diagram for explaining the form of each main process of the method for manufacturing a crystal diaphragm according to the present invention, using partial sectional views of the crystal film forming substrate.

  In each drawing, the same reference numerals indicate the same parts, and a part of the structure is not shown for clarity. Further, some of the dimensions shown in the figure are also exaggerated, and in particular, the thickness dimension of the crystal diaphragm is remarkably exaggerated.

  That is, in FIG. 1, FIG. 2 and FIG. 3, excitation electrodes 102 are respectively formed on both the front and back main surfaces of a thin plate-like crystal piece 101 having a substantially rectangular outer shape viewed from above the main surface. A pair of external connection electrodes 103 that are electrically connected to the respective excitation electrodes 102 are formed in the vicinity of each corner portion of one short side edge of the two short sides 101, so that the crystal diaphragm 100 It is composed.

Only the two side edges in the long side direction of the crystal piece 101 constituting the crystal vibrating plate 100 are bent only in one thickness direction (in FIG. 1, the main surface shown in FIG. 1A) over the entire length of these sides. The step portion 104 having the above-described shape is formed, and the entire crystal piece 101 including the step portion 104 is formed in a seamless integrated structure.

  As shown in FIG. 2, the height dimension t of the crystal diaphragm 100 is formed to be smaller than a numerical value obtained by doubling the thickness dimension t <b> 1 of the crystal piece 101. By adopting such a structure, it is possible to minimize the formation region of the crystal vibrating plate 100 while forming the stepped portion 104 and to maintain the strength as the crystal vibrating plate structure.

  Further, each excitation electrode 102 formed on both the front and back main surfaces of the crystal piece 101 so as to face each other with the crystal piece 101 interposed therebetween has one short side edge of the crystal piece 101 that is different between the front and back main surfaces. In order to establish electrical connection with a pair of external connection electrodes 103 formed in the vicinity of each corner of the crystal piece 101, the excitation electrode 103 and the external connection electrode are electrically connected to the front and back main surfaces of the crystal piece 101, respectively. An extraction electrode 105 is formed. Since the external connection electrode 103 must be formed on the surface of the stepped portion 104, the stepped portion 104 is inclined at an angle of less than 90 ° in the bent direction in order to facilitate the formation. (The surface of the stepped portion 104 is not perpendicular to the main surface other than the stepped portion of the crystal piece 101). In addition to the reason described above, this is also for facilitating the epitaxial growth of the crystal piece 101 in the method for manufacturing a crystal diaphragm described later.

Next, a method for manufacturing the crystal diaphragm 100 having the above-described form will be described.
That is, in the present invention, a vapor phase crystal growth apparatus 400 as shown in FIG. 4 is used to form the crystal piece 101 constituting the crystal diaphragm 100. This vapor phase crystal growth apparatus 400 generally includes a crystal growth chamber 403 provided therein with a crystal film forming substrate 401 and a support base 402 for supporting the crystal film forming substrate 401 at a predetermined position in the room. , A heater 404 for heating the inside of the crystal growth chamber 403, a crystal source gas supply means for allowing various crystal source gases to flow into the crystal growth chamber 403, and an exhaust means for exhausting gases in the unnecessary crystal growth chamber 403 4 is arranged in a predetermined position in the crystal growth chamber 403, and then a crystal source gas as shown in FIG. 4 is supplied from each crystal source gas supply means into the crystal growth chamber. While the crystal growth chamber 403 is heated by the heater 404 while being supplied at a predetermined flow rate, a crystal crystal is grown to a desired thickness on the main surface on the exposed side of the crystal growth chamber of the crystal film formation substrate 401.

  One embodiment of the quartz film forming substrate 401 used at that time is shown in FIG. This crystal film-forming substrate 401 has an integral structure using single crystal sapphire as a material, and the main surface of the crystal growth chamber exposed side has a main surface shape of the crystal piece 101 with the stepped portion 104 desired to be grown. A plurality of convex portions 502 having a stepped surface of the same shape formed on the top surface and protruding toward the outside of the quartz film formation substrate 401 are formed in a matrix at predetermined intervals. As a material for the quartz film forming substrate 401, it is possible to use a single crystal material such as silicon or gallium arsenide (GaAs) in addition to sapphire. A buffer layer (not shown) is formed on the top flat portion of the convex portion 502 of the quartz film forming substrate 401. This buffer layer is formed so that each crystal piece grown on the top surface of the convex portion in the manufacturing process can be easily separated from the crystal film formation substrate 401.

  Next, the form of each manufacturing process will be described with reference to the process diagram of FIG. 6 illustrated using a cross-sectional view of the quartz film forming substrate. 6 is the quartz film forming substrate 401 having the form shown in FIG.

  In FIG. 6 (a), first, a monolithic sapphire is used as a raw material, and the main surface of the crystal growth chamber exposed side has a main surface shape of the crystal piece 101 with the stepped portion 104 desired to be grown. A quartz crystal structure in which a plurality of convex portions 502 having a stepped surface of the same shape formed on the top surface and protruding toward the outside of the quartz film forming substrate 401 are formed in a matrix at predetermined intervals. A film substrate 401 is prepared.

  Next, in FIG. 6B, the prepared quartz film forming substrate 401 is placed on a support base 402 in a crystal growth chamber (not shown in FIG. 4) constituting the vapor phase crystal growth apparatus, The phase crystal growth apparatus is operated, and the crystal raw material gas is supplied to the heater (not shown in FIG. 4) while supplying the crystal raw material gas into the crystal growth chamber from various crystal raw material gas supply means constituting the vapor phase crystal growth apparatus. By heating the inside of the crystal growth chamber, a crystal piece 101 having a main surface shape that is the same shape as the stepped shape at the top of each convex portion 502 is grown at least on each convex portion 502 with a desired thickness and crystal orientation. Let For example, the crystal orientation is the same as that of a crystal piece cut from an artificial crystalline lens at a cut angle generally called AT cut, and when the desired excitation frequency is 100 MHz, the crystal is grown to a thickness of about 16.8 μm. Note that a buffer layer may be formed on at least the top of each convex portion 502 of the crystal film forming substrate 401 before the crystal piece 101 is formed. As this buffer layer, a crystal layer having a property different from that of the crystal piece 101 crystal or an amorphous crystal layer is used by being grown at a heating temperature different from that at the time of crystal piece 101 crystal growth. Form with 100 nm.

  Next, in FIG. 6C, the crystal film forming substrate 401 in which the crystal piece 101 grown to a desired thickness is formed on the top flat portion of each convex portion 502 is taken out from the crystal growth chamber. Then, by heating or cooling the joint between the crystal piece 101 and the top surface of the convex portion 502, the thermal characteristics such as the difference in the thermal expansion coefficient and the difference in the expansion direction of the materials joined at this joint are obtained. Due to the difference, thermal stress is generated in the bonded portion, and the bonded portion between the crystal piece 101 and the top surface of the convex portion 502 is separated, whereby a plurality of crystal pieces 101 with stepped portions 104 can be obtained simultaneously. When the buffer layer is formed, the crystal piece is formed in a form in which the buffer layer is attached. Even in the crystal piece in which the buffer layer is attached, the thickness of the buffer layer is very thin compared to the thickness of the crystal piece, so that it can be used as it is as the main structural material of the crystal diaphragm.

  Next, in FIG. 6D, a predetermined number of the separated crystal pieces 101 are collected using an alignment jig or the like, and Cr is applied to the surface of each crystal piece 101 using an existing vapor deposition method or sputtering method. The excitation electrode 102, the external connection electrode 103, and the extraction electrode 105 having a desired pattern of a laminated structure with Au are formed, and the crystal diaphragm 100 is manufactured.

  As described above, in the above-described method for manufacturing a crystal diaphragm according to the present invention, since the crystal piece 101 is manufactured, mechanical processing such as cutting is not applied to the crystal piece 101. The occurrence of chipping and chipping at the outer peripheral edge due to the occurrence of defects is almost eliminated, and the occurrence of defects in the vibration characteristics and drive characteristics of the crystal piece 101 due to the occurrence of such defects is almost eliminated. Furthermore, since such indefinite and indefinite chipping and chipping do not occur in each crystal piece, various characteristics of each crystal piece 101 are constant.

  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, the bending direction of the stepped portion formed on the top surface of each convex portion 502 of the crystal film forming substrate 401 used in the method for manufacturing a crystal diaphragm of the present invention is convex toward the outside of the top surface of the convex portion 502. However, the bending direction of the stepped portion may be concave toward the inside of the top surface of the convex portion 502.

1A and 1B show the appearance of a crystal diaphragm according to the present invention. FIG. 1A is a plan view of the crystal diaphragm as viewed from above the main surface corresponding to the bending direction of the stepped portion, and FIG. 1B is shown in FIG. It is a schematic sectional drawing at the time of cut | disconnecting by virtual cutting line AA '. FIG. 2 is a partially enlarged cross-sectional view showing an enlarged portion of the dotted circle A shown in FIG. FIG. 3 is an external perspective view showing the crystal diaphragm shown in FIGS. 1 and 2. FIG. 4 is an explanatory view showing a vapor phase crystal growth apparatus used in the method for manufacturing a quartz crystal plate according to the present invention. FIG. 5 shows a part of the embodiment of the crystal film forming substrate disposed on the support in the crystal growth chamber constituting the vapor phase crystal growth apparatus shown in FIG. 4 from above the main surface on the exposed side of the crystal growth chamber. FIG. FIG. 6 is a process diagram for explaining the form of each main process of the method for manufacturing a crystal diaphragm according to the present invention, using partial sectional views of the crystal film forming substrate. FIG. 7 is an external perspective view showing one embodiment of a conventional quartz diaphragm.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 ... Crystal diaphragm 101 ... Crystal piece 102 ... Excitation electrode 103 ... External connection electrode 104 ... Step part 105 ... Extraction electrode 400 ... Vapor phase crystal growth apparatus 401 ... Crystal deposition substrate 402 ... Support base 403 ... Crystal growth chamber 404 ... Heater 502 ... Convex

Claims (5)

Excitation electrodes are formed on both the front and back main surfaces of the thin plate-shaped crystal piece having a substantially rectangular main surface outline, and each of the excitation electrodes is electrically connected to the short edge of the crystal piece. In the crystal diaphragm on which the external connection electrode is formed,
A stepped portion having a shape bent only in one thickness direction over the entire length of the side is formed only on the two side edges in the long side direction of the crystal piece constituting the crystal vibrating plate, and includes the stepped portion. The quartz crystal diaphragm is characterized in that the whole quartz piece is formed with a seamless integrated structure.   2. The crystal diaphragm according to claim 1, wherein an external connection electrode is provided only on one short side edge portion of two short sides of the crystal diaphragm. .   The stepped portion according to claim 1, wherein the stepped portion is inclined at an angle of less than 90 ° toward the bent direction.   2. The quartz diaphragm according to claim 1, wherein a height dimension t of the quartz diaphragm is smaller than a value obtained by doubling a thickness dimension t1 of the quartz piece. External connection electrodes in which excitation electrodes are formed on both the front and back main surfaces of a thin plate-like crystal piece having a substantially rectangular main surface shape, and are electrically connected to the excitation electrodes on the short edge of the crystal piece. In the manufacturing method of the crystal diaphragm formed with
Using a vapor phase crystal growth apparatus, bend in only one thickness direction over the entire length of the side at a predetermined position in the crystal growth chamber constituting the vapor phase crystal growth apparatus, only at two side edges in the desired long side direction. A plurality of convex portions formed on the top surface of a stepped surface having the same shape as the main surface shape of the thin plate-like crystal piece with a stepped portion in the form of A step of disposing the quartz film forming substrate formed in a form in a form in which the top surface of each convex portion is directed upward or toward the crystal raw material gas inlet;
The crystal element on a surface of the quartz deposition substrate, the steps of the vapor-phase crystal growth method, the excitation region of the crystal blank is epitaxially grown at a predetermined crystal orientation to a thickness of excitation at a desired frequency,
Taking out the crystal film-forming substrate on which the crystal piece has grown on the surface from the crystal growth chamber, and separating the crystal piece formed on the top surface of each convex portion from the top surface of each convex portion;
Forming an excitation electrode, an external connection electrode, and an extraction electrode for electrically connecting the excitation electrode and the external connection electrode on the surface of each of the separated crystal pieces. A method for manufacturing a quartz diaphragm.

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