JP2003110388A - Piezoelectric vibrating element, method of manufacturing the same, and piezoelectric device - Google Patents

Abstract

(57) [Problem] To perform an etching process to form a concave shape on a crystal blank by wet etching, and simultaneously form a contour of the crystal blank, the conditions for forming the concave shape and the contour are different, and optimization is difficult. The surface roughness of the main surface of the bottom processed into a concave shape is poor, the degree of contamination of the etching solution is doubled, and it becomes difficult to control the etching rate. In addition, since it is necessary to form a region penetrating through each crystal blank, the number of crystal blanks to be removed is small, and the dimensional accuracy of an electrode formed by the photolithography technique is deteriorated. In addition, it is necessary to reduce the sub-vibration for stabilizing the characteristics in consideration of productivity. A plurality of concave shapes are simultaneously formed on a wafer by etching, and then cut to separate into a plurality of quartz pieces. Further, in the etching process, the vicinity of the later cutting process is simultaneously etched and chamfered.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present application mainly detects consumer products such as televisions, clocks for computers, frequency sources used for high-speed and large-capacity communication such as wireless communication and optical communication, and substances. The present invention also relates to a piezoelectric device that uses piezoelectricity, such as a sensor that detects pressure or acceleration. In particular, with a thin crystal oscillator that oscillates at a fundamental wave of 100 MHz or more, a piezoelectric vibrating element that prevents unwanted vibration such as sub-vibration from affecting the main vibration as much as possible, and a large amount of this piezoelectric vibrating element is manufactured accurately. And a piezoelectric device using the piezoelectric vibrating element.

[0002]

2. Description of the Related Art A crystal oscillator is an important component for supplying a reference frequency to communication equipment. In recent years, with the advent of high-speed, large-capacity communication equipment, the frequency of each equipment has increased, and at the same time, it has been required to supply more crystal resonators that directly increase the resonance frequency and reduce noise such as jitter (ELECTRONIC). DESIGN March6
0200 p112). Generally, it is easier to suppress noise if the fundamental frequency of the crystal unit is higher than that when a PLL circuit realizes a higher frequency. In order to increase the resonance frequency of a crystal unit such as AT-cut and handle it in the VHF band, the plate thickness becomes higher as the plate thickness of the excitation portion where the piezoelectric body excites the main vibration becomes thinner.

In particular, when it is used as a frequency generation source in which the stability of electrical characteristics is required, when the resonance frequency of fundamental wave vibration reaches 100 MHz or more due to the advance of high frequency, the thickness of the quartz plate is about 17 μm or less. Becomes Therefore, the resonance frequency fluctuates due to the influence of external shock such as acceleration and shock, and the handling at the time of manufacturing is bad. A general crystal oscillator is a flat plate type, and a flat crystal piece is used. The flat means a plate-shaped crystal piece in which one main surface and the other main surface are substantially parallel to each other and have a constant plate thickness over the entire surface. In order to avoid the adverse effects of using a thin plate, a flat plate-shaped crystal piece is provided with a thicker frame portion on the outer periphery of a normal flat plate-shaped crystal piece, and the crystal has a concave shape when viewed in cross section. A concave quartz vibrating element utilizing a piece has already been invented. In the present specification, the thin plate portion of the concave crystal piece is referred to as a thin plate portion. Concave quartz crystal vibrating elements such as round ones and square ones have been announced in and out of the 1970s (US Pat. No. 3,694,677). In addition, the vibration mode of the concave quartz crystal vibrating element has been studied by Nakazawa et al. (Science and Technical Bulletin US76-16,7, 1976).
In order to improve the value, a convex shape is formed on the surface of the concave quartz piece, and the frequency temperature characteristic is studied (The Institute of Electrical Engineers of Japan, Showa 57-2, p59). When this thin plate that is affected by external shock is used, the change in weight on the electrode surface is felt more sensitively than the piezoelectric vibrating element with a low thickness at low frequencies, so a minute change such as for gas detection can be detected or the displacement of the weight point can be detected. There is also an application to use as a high performance sensor for acceleration measurement.

[0004] In recent years, with the improvement of technical capabilities such as grinding and polishing, a technique for handling a thin plate-shaped piezoelectric piece and a technique for fixing it to a cage have been improved by the progress of various elemental technologies. If the plate thickness is constant, the problem of thin plate is solved and the flat plate type is used. 10 μm
Mount a thin flat crystal piece with bumps, or SMD
A device mounted on a package to form a surface-mounted crystal unit has also been devised. With a crystal vibrating element with the same external dimensions,
The flat plate shape may be more advantageous than the concave shape as follows. When the area of the electrode is an important design parameter in order to reduce the capacitance ratio and increase the variable width of the frequency for a voltage controlled crystal oscillator (VCXO), etc., in piezoelectric devices such as pressure sensors, The larger the electrode, the easier it is to pick up charges, that is, if the electrode is large to obtain sensitivity or needs a large area to have various shapes, the main surface area is wider than the plate thickness. Such as when you want to take.

In the present specification, a piezoelectric piece composed of a thin plate part of which a part of the main surface has a thin plate thickness and a frame part having a large plate thickness excluding the part is a concave piezoelectric piece, and the reverse. Also called a mesa shape. In this specification, reducing the plate thickness of a part of the main surface is referred to as forming a concave shape. The concave thin plate portion is called a thin plate portion, and the thick plate portion is called a frame portion. Since it is necessary to control the thickness of the thin plate portion at the bottom to form the concave shape, it is generally difficult to mass-produce it. Further, at present, the plate thickness is about 35 μm or more, which is generally mounted on the surface mount type crystal oscillator or the crystal oscillator, but the flat plate type crystal piece. For this reason, it is easier to divert the conventional equipment by handling the flat-plate type crystal piece that has been used in the conventional crystal unit manufacturing. As described above, the flat-plate type crystal resonator has many advantages over the concave-type crystal vibrating element. There are many advantages, and there is a high possibility that they will be used properly depending on the purpose of use.

The concave quartz piece forms a concave shape on a flat main surface. The concave shape is generally formed by wet etching in which a quartz crystal is dissolved and etched using an etching liquid containing hydrofluoric acid or ammonium fluoride, or CF4.
Chemical processing methods such as dry etching that etches quartz using reactive gas such as CHF3 and C2H6, and physical processing methods that uses shock such as laser, ultrasonic wave and sand blast. is there.
Dry etching can be processed without roughening the surface roughness of the main surface of the thin plate portion, but the etching rate is slow at 500 Å / min and processing takes time. The physical processing method causes individual processing, cracks due to physical impact, and deterioration of the electrical characteristics of the processed layer. Wet etching is a method of melting and processing a crystal using a liquid. The etching liquid may be mixed with the above-mentioned other additives to stabilize the etching rate and improve the surface roughness. A large amount of crystal pieces and wafers can be processed at the same time with excellent productivity, and the etching rate is as fast as about 2 μm / min in the direction perpendicular to the AT-cut surface. Usually, the etching liquid is placed in a Teflon (registered trademark) container and the temperature is adjusted to about 50 to 90 degrees, and the crystal is dipped in this. The crystal may be rocked. As an example of processing to reduce the plate thickness,
A protective film is formed on the entire main surface, and then the protective film in the area corresponding to the thin plate portion for thinning the plate thickness is removed, and the portion where the protective film is removed by dipping in the etching liquid is processed to reduce the plate thickness, Form a depression on the main surface. At present, when viewed from the direction perpendicular to the main surface, a concave crystal resonator having a thin plate portion having a square or circular shape is mainly used. The etching process in this specification mainly refers to the process of a wafer by wet etching.

In the etching process of the quartz piece by wet etching, the contour is usually formed at the same time when the concave shape is formed. In the tuning fork type crystal vibrating element, wet etching is generally used to form the contour. However, in order to completely penetrate the contour and ensure dimensional accuracy, it is necessary to separate adjacent crystal pieces from each other at a constant distance, and therefore the number of crystal pieces taken from one wafer is reduced. Furthermore, it is necessary to make the connecting portion and the frame portion so that the crystal pieces do not become disjoined after the etching process, and the number that can be taken becomes smaller. Further, in the concave crystal piece, the thin plate portion is etched only from one main surface, and the contour portion is etched from both main surfaces. At this time, the formation of the contour requires a sufficient rocking of the wafer in order to eliminate the variation in the dimension of the contour, but the formation of the concave shape causes the surface to become rough if the optimum rocking is performed for the formation of the contour. The conditions such as the liquid composition and temperature of wet etching are also different.

In the present specification, the piezoelectric piece means a crystal piece cut into a certain geometrical shape, size and angle with respect to the crystal axis. Further, an element that utilizes piezoelectricity, such as an electrode arranged on a piezoelectric piece to apply an electric charge to obtain vibration, is called a piezoelectric vibrating element, and the piezoelectric vibrating element is enclosed or sealed in a holder to be used as a piezoelectric device. In AT cut and SC cut, electrodes are arranged on at least the front and back main surfaces, respectively.
In a filter or the like, two or more electrodes may be arranged on one main surface. Piezoelectric devices are piezoelectric vibrators that are enclosed in a cage and sealed.They are oscillators, oscillators, sensors, optical elements, etc., and the crystals of the piezoelectric body are piezoelectric crystals such as langasite and lithium niobate in addition to quartz. Is a single crystal. In the case of crystal, the piezoelectric piece is a crystal piece, the piezoelectric vibrating element is a crystal vibrating element composed of a crystal piece and electrodes arranged on the crystal piece, and the piezoelectric device holds the crystal vibrating element. It refers to a crystal unit enclosed in a container, a crystal oscillator, or a sensor component or optical element that uses crystal.

In the case of an AT-cut crystal unit, as shown in FIG. 11, the main vibration to be used is the thickness-shear vibration (a) and is used as the main vibration, but bending vibration (d), extension vibration (e) or contour There are high-order unnecessary secondary vibrations such as sliding vibration (f), and in addition to the secondary vibrations with the dimensions of the contour of these crystal pieces as parameters, the thickness torsional vibration mode (b) and the inharmonic mode ( Basic vibration such as c) or secondary vibration of higher order is also generated. Reference numeral 901 indicates a positive charge region, 902 indicates a negative charge region, and the arrow in FIG. 9 indicates the displacement direction. The sub-vibration has an effect when it exists near the resonance frequency of the main vibration. For example, when adjusting the frequency by processing the electrode, the adjustment accuracy is deteriorated, or it is combined with the main vibration to change the resonance frequency by the capacitance. ,
When the temperature is changed, it affects the main vibration and the main vibration causes a frequency jump in which the frequency changes discontinuously. At times, the vibration is stopped and the characteristics of the piezoelectric device become very unstable. Therefore, in order to damp the secondary vibration or reduce the coupling by separating from the resonance frequency of the main vibration, beveling processing or convex processing is generally performed.

The beveling process is a process for chamfering the edges of the main surface of the piezoelectric piece. Normally, the slanted surface is ground and slanted with respect to the main surface. In the convex processing, the surface shape is a convex lens shape and one side is convex or both sides are convex. When chamfering a crystal piece such as a crystal unit,
Flexural vibrations, extensional vibrations, and contour slipping vibrations can be attenuated, and the resonance frequencies of these secondary vibrations can be greatly changed. These make it possible to approach the ideal thickness shear vibration (Shotaro Okano, "Crystal Frequency Control Device" p64). The vibration displacement of the thickness shear vibration is concentrated in the center of the electrode to reduce the support loss at the edge (Sadao Taki, "Synthetic Quartz and Its Electrical Applications," p101). As a result, the characteristics of the thickness-shear vibration, which is the main vibration, in particular, the influence of the sub-vibration on the main vibration due to a temperature change is improved, and at the same time, the characteristic change in use as a piezoelectric device is reduced. In this specification, a chamfered partial chamfered portion is added to the piezoelectric vibrating element, which has the same effect as that obtained by the conventional beveling process. The dimensions of the chamfer have also been thoroughly studied. The beveling process is created by using an apparatus such as a grinding machine or a polishing machine, and has been manufactured in a fixed quantity for high-performance piezoelectric devices. However, since the beveling process is performed individually for each crystal piece, it is troublesome and difficult to mass-produce. Further, the difficulty of processing depends on the shape of the crystal piece, such as the circular shape is easy to process and the square shape is difficult to process, and it is difficult to cope with the diversified crystal shape in recent years, and it is difficult to reduce the cost and cost.

[0011]

As described above, when a crystal piece is processed by etching, when forming a contour, a penetrating portion is provided between hydrogen pieces, and a sufficient strength required for handling is obtained. Since it takes an area to form the frame part, the number of pieces taken out is small and the productivity is poor. Further, when forming a concave shape, if it is performed simultaneously with the formation of the contour, the wet etching conditions are different and optimization cannot be performed, so the processing accuracy is poor and the dimensional accuracy and the roughness of the main surface of the thin plate portion are poor. . Further, in forming the contour of the crystal piece by the conventional wet etching having a penetrating contour, when the electrodes are finely formed by the photolithography technique, the positional deviation and the dimensional accuracy are deteriorated due to the unevenness of the resist and the distortion of the crystal piece. In addition, when chamfering the crystal piece to reduce secondary vibration,
The difficulty of processing changes depending on the contour shape of the crystal piece, and it is necessary to process each crystal piece individually, resulting in poor productivity. Further, chipping or the like is likely to occur when the crystal piece is cut by a cutting process such as a dicing saw.

The present invention has been made in consideration of the above problems, and is excellent in the dimensional accuracy of the outline of the crystal piece and the surface roughness of the main surface.
It is another object of the present invention to provide a piezoelectric vibrating element having stable characteristics against secondary vibration and a piezoelectric device using the same. Another object of the present invention is to provide a method of manufacturing the piezoelectric vibrating element as described above while ensuring the production efficiency of chamfering.

[0013]

[Means for Solving the Problems] A piezoelectric piece composed of a thin plate part having a thin plate part of the main surface, and a frame part having a thick plate part excluding the part, and main parts on both sides of the thin plate part. In a piezoelectric vibrating element having electrodes arranged on a surface, the piezoelectric piece is formed by removing at least one of wet etching and dry etching from a thickness of a part of a wafer on which two or more piezoelectric pieces are taken. The wafer is etched so as to be thin, and then the wafer is cut by using one of a dicing saw and a wire saw to be separated and formed. Further, the piezoelectric piece has a chamfered portion in which at least one main surface is chamfered at the same time by etching the vicinity of a cutting region to be cut by the cutting by the etching.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION (Embodiment 1) FIG. 1 is a diagram showing a configuration of the present invention. Large-capacity high-speed communication equipment requires a piezoelectric device that oscillates a higher frequency, but AT-cut crystal oscillators used as frequency generators need to be thin to increase the frequency. There is a concave quartz piece in which the plate thickness of a part of the main surface that solves the problem of the thin plate is reduced. Further, when etching is performed such as forming a concave shape on the crystal piece by wet etching, but when the contour is formed at the same time, a gap is formed in each hydrogen piece, and the number of hydrogen pieces taken out is small, resulting in poor productivity. Further, since the condition for forming the concave shape and the condition for forming the contour are different and optimization cannot be performed, the dimensional accuracy of the crystal piece is poor and the roughness of the main surface of the thin plate portion is poor. Further, when performing the beveling process to reduce the secondary vibration, it is necessary to process each crystal piece individually, resulting in poor productivity. The present invention has been made in consideration of the above problems, and a piezoelectric vibrating element which is excellent in dimensional accuracy and surface roughness of the main surface and has stable characteristics due to measures against sub-vibration, a method for manufacturing the same, and use thereof Provided is a piezoelectric device.

FIG. 1 shows a quartz plate 1 composed of a thin plate portion 4 in which a part of the main surface 2 has a thin plate thickness, and a frame portion 5 having a thick plate thickness excluding the above part, and both sides of the thin plate part 4. It is a crystal vibrating element having electrodes 101 and 102 arranged on the main surfaces 2 and 3. Cage 4
It is enclosed in No. 05 and used as a crystal oscillator, that is, a piezoelectric device in this specification. Usually, the crystal piece 1 is held together with the electrodes, and the one enclosed in the holder is called a crystal resonator. (Explanation and application of crystal device Japan Crystal Device Industry Association 1996
(October year). Other crystals that can be used for the piezoelectric piece include langasite, lithium niobate, and other single crystals exhibiting piezoelectricity. In particular, quartz is currently generally used as a frequency generation source. Langasite is expected to be a stable frequency source similar to quartz. The arrow on the right side of the figure indicates the crystal axis indicating the geometrical orientation of the crystal blank 1. In this example, since the AT-cut crystal piece 1 is used and the Y-cut crystal piece perpendicular to the Y-axis can be cut at a position rotated around the X-axis, the Z-axis is rotated from the normal axial direction. It is displayed as'and Y '. The direction of the arrow is +.

FIG. 2 is a sectional view of the crystal blank 1 taken along a plane perpendicular to the Z'axis. FIG. 3 is a cross-sectional view showing the pattern of the protective films 302 and 303 that determines the outer shape of the crystal piece when the crystal piece 1 is etched by wet etching as viewed from the same direction as FIG. FIG. 4 is an outline of a process for manufacturing a piezoelectric device from the wafer 301. FIG. 5 is an outline of the process of FIG. 4 viewed from the direction perpendicular to y ′. Figure 6
Is an outline of a conventional etching process by wet etching. FIG. 7 shows an example of the piezoelectric piece 1 used in the piezoelectric vibrating element of the present invention. FIG. 8 shows the protective film 3 of the present invention.
It is an example of patterns of 02 and 303. FIG. 9 shows a piezoelectric vibrating element without chamfering. FIG. 10 is a sectional view of FIG.

3 to 10 will be mainly described with reference to FIGS. 1 and 2, and an example of the manufacturing process will be described with reference to FIG. Reference numeral 1 is a crystal piece, and an AT-cut wafer 301 is dipped in an etching solution to form a concave shape, and the wafer 301 is cut and processed to form a cut surface 7 to form a contour, thereby forming a plurality of crystal pieces 1. To separate. Further, the separated individual crystal pieces 1 are thinned by dry etching to adjust the thickness to form a thin plate portion 4 having a thickness 201. The concave shape is near the center of the crystal blank 1, and it can be seen from FIG. 2 that the concave shape is present. The contour in this specification means the contour of the crystal piece as seen from the direction perpendicular to the main surface 2 as shown in FIG. Crystal piece 1
The cutting angle of is determined by the wafer formation, but SC cutting or the like is mainly used in addition to AT cutting. SC cut is used as a frequency generation source with highly stable characteristics. A wafer is a plate with a certain thickness, and a crystal plate called Lambert is cut by AT cutting with a band saw or a wire saw, and the thickness is reduced by polishing. In some cases, different types of abrasive grains are used. Polishing is performed so that both main surfaces 2 and 3 are mirror surfaces. The thickness of the wafer 301 of this example is about 80 μm. The main surface means a surface having the largest area on the crystal blank 1 or the wafer 301, and in this example, a surface parallel to the AT-cut surface, a main surface 2 which is a surface perpendicular to the y ′ axis in FIG. It corresponds to the main surface 3 on the back side. Further, the front is the front as shown in FIG. 1, and is a surface that is located on the opposite side to the back and is perpendicular to the y ′ axis, and either the front or the back may be either. That is, the front side in this specification means one main surface of the piezoelectric piece, and the back side means the other main surface.

Reference numeral 2 is a main surface. It has a dented shape near the center. As shown in FIG. 2, the plate thickness 201 is thinner than the periphery of the thin plate portion 4. The plate thickness is the distance between the main surface 2 and the main surface 3. The plate thickness 201 of the thin plate portion 4 is 10 μm. Further, the surface roughness of the main surface 2 suppresses the unevenness to 30 nm or less. It is difficult to suppress the unevenness to 30 nm or less by the conventional manufacturing method, and the yield is low. The dimensions of the main surface 2 are indicated by the front-side main surface dimension 203. Reference numeral 3 denotes a main surface that faces the main surface 2 and is parallel to the main surface 2. The size of the main surface 3 is indicated by the back main surface size 202. In this example, the back main surface dimension 202 is larger than the front main surface dimension 203. As a result, even if the cutting surface 7 perpendicular to the main surfaces 2 and 3 is provided, the chamfered portion 6 that is an oblique surface is formed. Reference numeral 4 is a thin plate portion, and the main surfaces 2, 3
The electrodes 101 and 102 facing each other are arranged to obtain the thickness shear vibration as the main vibration. Although the crystal piece 1 has a rectangular outline, it may have a circular shape, a square shape, or a triangular shape. A circle is a shape that is easy to manufacture and is generally used, and a triangle is easy to form a contour by utilizing the three-fold symmetry of crystal and the like, and stable dimensional accuracy can be obtained. Reference numeral 5 denotes a frame portion, which is made of the same material as the thin plate portion 4 and is continuous with the thin plate portion 4.

The chamfered portion 6 is formed simultaneously with the etching process for forming the concave shape. The crystal vibrating element of this example has a main surface 2
By forming the chamfered portion 6 at the edge of the sub-vibration, the sub-vibration is reduced as in the conventional beveling process, or its resonance frequency is changed so as to be separated from the resonance frequency of the main vibration. The edge of the main surface 2 is the boundary between the main surface 2 and the cut surface 7 in FIG. 9, and in this example, a chamfered portion 6 is formed between the main surface 2 and the cut surface 7 as shown in FIG. I am doing it. The dimensions of the chamfered portion 6 are indicated by the chamfered portion width dimension 204 and the chamfered portion depth dimension 310. Each dimension of the chamfered portion 6 largely depends on the pattern of the protective film 302 formed on the main surface 2. Further, when the chamfered portion 6 is formed by wet etching, each dimension of the chamfered portion 6 is influenced by the anisotropy of the crystal and is also influenced by the difference in the etching rate due to the undercut portion 311 due to the etching process and the crystal anisotropy. Then, the correction is mainly performed by the pattern of the protective film 302. As a result, the chamfering is performed with a free dimension to reduce the secondary vibration, adjust the resonance frequency of the secondary vibration arbitrarily, and further secure or adjust the strength of the wafer 301.

Reference numeral 7 denotes a cut surface, which is formed when the concave shape is formed on the main surface 2 by wet etching and then cut by a dicing saw or a wire saw to separate the individual crystal pieces 1. Before the cutting process, the wafer 301 was constituted by connecting to a plurality of crystal pieces on this surface. The cutting surface 7 is substantially perpendicular to the main surface 3. 10
Reference numerals 1 and 102 are electrodes. Mainly Au, Ag, Al, N
i, Cr, alloys of these, and laminated layers of these. Au has excellent corrosion resistance and maintains stable characteristics for a long time. Al is lighter than Au and does not give extra deformation due to gravity when the plate thickness is very thin such as 10 μm, and also slows down the frequency adjustment speed to facilitate the adjustment. In this example, Cr has a two-layer structure of 20Å and Au is 600Å.
r is used as a cushioning material for Au and quartz. Also electrode 1
No. 01 has holes formed in the mask.
In order to secure dimensional accuracy, a metal film is once attached to the entire main surface 3 and a shape is created by photolithography technology. The electrode 101 may also be formed in this way, but in the case of contact exposure,
Since the quartz piece having a concave shape forms a gap with the exposure mask, the dimensional accuracy is lower than that of forming the shape on a flat surface such as the main surface 3. The electrode 102 is spread from the main surface 3 to the main surface 2, and is a continuous metal film that is also disposed on the chamfered portion 6 and a part of the cut surface. It suffices if there is continuity even if it is discontinuous.

In FIG. 3, protective films 302 and 303 durable to etching are formed on a quartz wafer 301, and the etching portions 307 and 308 are dissolved by immersing the protective films 302 and 303 in an etching solution that dissolves the quartz. It is the figure which showed that. The protective films 302 and 303 are mainly Au, Pt, Cr, Ni, alloys thereof, or films in which these are stacked. Especially, Cr and Au on the crystal piece 1
The protective film having a two-layer structure for depositing is generally used in the etching process of quartz. Ni, Au instead of Cr
A similar solution-resistant protective film can be obtained by using Pt instead of, but it is selected depending on the material cost and the growth of the alloy layer. The protective films 302 and 303 need only have durability to protect the crystal blank 1 from being dissolved by the etching liquid used for wet etching, and may be formed of an organic material. The main surface 2 covered with the protective film 302 remains undissolved, and the portion where the main surface 2 is exposed without being covered with the protective film 302 is dissolved and dented from the main surface 2. The protective films 302 and 303 are formed on the main surfaces 2 and 3 in a pattern having an arbitrary shape, and the crystal blank 1 is processed arbitrarily. In this example, the pattern is formed by removing a part of the protective film 302 formed on the entire main surface 2. That is, in order to form the thin plate portion 401, the protective film removing portion 30
4 is provided and the etching part 307 is dissolved. At this time, the protective film removing portion 30 is formed at the same time to form the chamfered portion 6.
5 is provided to dissolve the etching portion 308.

As described above, the protective film removing portions 304, 30
The pattern of the protective film 302 is determined by the dimension of 5. In this example, the removed portion width dimension 306 of 30 μm is obtained and the etching portion width dimension 306 is set to 5 by etching.
The depth of the chamfered portion 310 was 0 μm, and the depth 310 was 40 μm. If the removed portion width dimension 306 is increased, the chamfered portion depth dimension 310 becomes a recess up to the same depth as the etching portion 307, and a surface parallel to the main surface 2 is formed on the bottom in the same manner as the etching portion 307. The cross section is as shown in FIG. The formation of the undercut portion 311 is confirmed because the removal width dimension 306 of FIG. 3 is smaller than the etching portion width dimension 301. Width of removed part 306
When is smaller, each dimension is also smaller and can be adjusted. When the chamfered portion depth dimension 310 is set to 0 μm, etching processing is not performed, and a cross section as shown in FIG. Protective film 303
Is formed similarly to the protective film 302, but in this example, is formed on the entire main surface 3 and does not have any pattern. However, by forming the protective film 303 in an arbitrary pattern, the chamfered portion 6 can be arbitrarily formed as shown in (r), (s), and (v) of FIG.
Alternatively, the entire surface may be etched by not forming the protective film 303 on the main surface 3 as shown in (t) and (u) of FIG.

A cutting line 312 is cut along this line. The cutting process is performed at least after forming a concave shape in a part of the main surface 2 by etching process, that is, after forming the thin plate portion 402. In this example, a dicing saw was used. The wafers 301 may be stacked and solidified with an adhesive, and may be cut and processed, which is selected depending on the labor and cost. In the cutting process by dicing, the electrode 101 or the electrode 102 is formed before the cutting process, and the reference line of the cutting line 312 is arranged at the same time.
It is easy to ensure accuracy by cutting. In the method of leaving the reference line of the cutting line 312 on the main surface 3 in a pattern without removing a part of the protective film 303 in peeling, the number of steps may be saved. In this example, the main surface 3 from which the protective films 302 and 303 have been peeled off is directly aligned using a reference line formed of a resist, and x
It was cut at a constant interval of 2 mm in the direction and 4 mm in the z'direction. At this time, the cutting is performed near the center of the etching portion 308, but it may be slightly displaced due to the anisotropy of the crystal, the bottom of the V shape may not be present, and the surface of the chamfered portion 6 may be uneven. It is sufficient that the chamfered portion 6 is formed. In particular, the back side principal surface dimension 202 is the front side principal surface dimension 203.
Get bigger. When cutting in a rectangular shape, the cutting line 312
The outline dimension of the crystal blank 1 is determined by the interval dimension of. By forming the outline of the crystal piece 1 by cutting and separating it from the wafer 301, as shown in FIG. 6D, a space is provided between adjacent crystal pieces 1 to form a through portion 604, or a frame for handling. The portion 602 is not provided in a large area.
Since the crystal pieces 1 are adjacent to each other as described above, the number of the crystal pieces 1 taken from the wafer 301 increases. In this example, 50 pieces were taken from the 1-inch wafer 301.

The thin plate portion 402 formed by etching
And the contour processing by cutting are separately performed, so that the main surface 2 of the thin plate portion 402 is wet-etched under the optimum conditions. Further, after the chamfered portion 6 is formed, a cutting process is performed to minimize chipping of the edge. Further, unlike the conventional wet etching process shown in FIG. 6, since the crystal blank 1 is not supported by a part thereof, it is less likely to fall off during the process and the yield is increased. Further, when the electrode 102 is formed in a fine pattern by the photolithography technique, as compared with FIG. 6D, since the penetrating portion 604 does not exist as in FIG. Since it is not deformed due to contact exposure or unevenness of the resist, positional deviation and dimensional deviation are prevented and electrodes are accurately formed.

FIG. 4 is an outline of a crystal oscillator manufacturing procedure. Fifty concave shapes are formed in a matrix on a wafer 301 by etching by wet etching, and then 50 concaves are formed by cutting with a dicing saw. The crystal element 1 is separated, and the plate thickness is finely adjusted by dry etching, and then electrodes are formed to obtain a crystal vibrating element. Further, this crystal vibrating element is fixed to a holder 405 to fix the electrode 1
02 is cut with an ion gun, the frequency is adjusted, and sealed to form a crystal unit. Detailed description will be given later. 5A to 5C are views of FIG. 4 viewed from the direction perpendicular to the y ′ axis, and substantially correspond to FIGS. 4A to 4C. Figure 4
A part of the protective film 302 of (c) is removed to provide protective film removing portions 304 and 305 to expose the main surfaces 2 and 3.
FIG. 5D clearly shows the position where the cutting line 312 is entered after the etching process of FIG. 5C is performed. By the etching process, the protective film removing portion 304 becomes the thin plate portion 4.
02, a concave shape is formed, and at the same time, the protective film removing portion 3
Reference numeral 05 forms the chamfer 6. Although FIG. 5 shows that nine crystal pieces are taken, actually, the crystal pieces 1 are arrayed in a matrix form and 50 pieces are taken at the same time. Further, a frame portion 501 may be provided as a region for handling. If you don't need it, you don't have to provide it, and the number can be increased. Further, when the chamfered portion width dimension 204 and the chamfered portion depth dimension 310 (c) are set to be sufficiently large, when the strength of the connecting portions 313 of the individual crystal pieces 1 is not sufficient after etching, the frame portion 501 is sufficiently set, It prevents the wafer 301 from cracking and facilitates handling.

FIG. 6 is an outline of a conventional procedure for manufacturing a quartz crystal vibration element using wet etching, which is shown corresponding to FIG. It is used in tuning fork crystal vibrating elements.
FIG. 6A shows the formation of the wafer 301, and FIG.
Forms a protective film 302 on the entire main surface 2. FIG. 6 (c)
With the photolithography technique, the outline of the crystal piece 1 and the connecting portion 601
The protective film 302 is formed in a pattern having a frame portion 602. The protective film removing portion 603 is penetrated by etching to form a penetrating portion 604 to substantially determine the contour of the crystal blank 1. By cutting the vicinity of the connection portion 601 along the cutting line 312 of FIG. 6D, the individual crystal pieces 1 are separated. At this time, the electrodes may be formed before the cutting process, which saves the labor of individually handling and processing the crystal pieces 1. In FIG. 5, the positions of the etching portion width dimension 309 and the cutting line 312 are adjusted to form the chamfered portion 6 having an arbitrary chamfered portion width dimension 204 and chamfered portion depth dimension 310 to form the outline of the crystal blank 1. In FIG. 6, since the outline of the crystal blank 1 is formed only by etching, the chamfered portion 6 is formed by the anisotropy or undercut of the crystal, but the cut surface 7 is not formed. Also,
The frame portion 602 is formed to facilitate handling with the connection portion 601, and has a larger area than the frame portion 501 in FIG. 5 because it is necessary for the frame portion 602 only to have strength to withstand handling.

FIG. 7 is a sectional view showing an example of the crystal blank 1.
FIG. 8 shows an example of patterns of the protective films 302 and 303,
Since the shape of the crystal piece 1 of FIG. 7 is almost determined by the pattern of FIG. 8, it will be described collectively. In the same state as the crystal piece 1 in FIG. 4E, after the cutting process step, 402 is a dry etching part. FIG. 7A has the same shape as this example, and is formed by etching the pattern of the protective films 302 and 303 of FIG. 8O. In FIG. 7B, the edge of the main surface 3 is also chamfered. A protective film 3 having a pattern as shown in FIG.
02 as well as the protective film 303
It is formed by etching in FIG. 8 (s) which is a pattern provided with 02. At this time, the width dimension 306 of the removed portion is made smaller than that of FIG. 8 (o) to adjust the depth dimension 310 of the chamfered portion to secure the strength of the wafer 301 that can withstand handling after etching. If the width of the removed portion 306 is large enough, the main surface 2 on both sides
Since it is etched from 3, it penetrates. Figure 7
In (c), the contour of the crystal blank 1 is formed only by cutting without forming the etching portion 308. The chamfered portion 6 is not formed by using the protective films 302 and 303 having a pattern as shown in FIG.

FIG. 7 (d) shows that the thin plate portion 4 is displaced in one direction and is formed at a distance from the region where the thin plate portion 4 is supported by the retainer 405, so that the influence can be reduced. And This can be achieved by forming the protective film 302 by shifting the position of the protective film removing portion 304 in FIG. Figure 7
(E) has a shape in which the frame portion 5 does not exist in one direction, but the plate thickness of a part of the main surface 2 is the same as that of the other ones. A protective film 30 having a pattern as shown in FIG.
2 may be formed, and the cutting line 312 may be provided in the melting portion 307. This is because it is easy to reduce the size of the crystal blank 1 by omitting the frame portion 5. In FIG. 7F, the chamfered portion width dimension 310 and the chamfered portion depth dimension 204 of the chamfered portion 6 are (a).
Small compared to. This is adjusted by reducing the width 306 of the removed portion in FIG. Further, the protective film removing portion 305 may be shifted to adjust the position with respect to the cutting line 312. This makes it possible to form an arbitrary chamfered portion 6 by adjusting the error due to the anisotropy of the crystal.

In FIG. 7G, etching portions 307 and 308 are formed on different main surfaces. The main surface 2 has a concave shape to form a thin plate portion 4, and the main surface 3 has an etching portion 308 and a chamfered portion 6. The protective films 302 and 303 may be formed in the pattern of FIG. FIG. 7H has a main surface 701, and is used for surely cutting along a plane perpendicular to the cutting surface 312. However, generally, since a brittle thin portion is formed around the periphery, the contour is liable to be uneven and not used. As shown in FIG. 8 (p), the width of the removed portion 306 may be secured sufficiently wider than in FIG. 8 (o). 7 (i) and 7 (j) may have a dry etching portion 402 on the main surface 2, and the main surface 2 may be dry-etched. As shown in FIG. 7K, the thin plate portion 4 may be formed by forming a concave shape on both the main surfaces 2 and 3. The protective films 301 and 302 of FIG. 8 (t) may be formed. The area of the main surface of the thin plate portion 4 may be different on both sides as shown in FIG. 7 (m). 8 (o), 8 (p), and 8 (q) show the protective film 30.
3 may not be formed, but the plate thickness of the frame portion 5 is also thin.
However, since the etching depth is reduced from both the main surfaces, the surface roughness of the main surface 2 is improved because the processing depth is reduced. The dry etching part 402 was processed by dry etching. The thin plate portion 401 roughly formed by wet etching having a high etching rate is finely adjusted in thickness by utilizing the fact that the etching rate is slow, and is adjusted to the thin plate portion 4 having the plate thickness 204. Further, the plate thickness maintenance adjustment by dry etching is less rough than the surface roughness treated by using an etching liquid having a slow etching rate. However,
Since the etching rate is as slow as 500 Å / min, the plate thickness adjustment by dry etching is limited to about 10 μm from the viewpoint of cost due to processing time.

An example of the procedure for manufacturing the piezoelectric device will be described below with reference to FIG. The crystal oscillator, which is the piezoelectric device of this example, includes a crystal piece 1, electrodes 101 and 102, a lid 410 that is a lid, and a holder 405. 3 is a cross section in the same direction as FIG. 2. FIG. 4 (a) shows a wafer forming process by machining, in which a crystal plate called Lambert is cut with a band saw or a wire saw to a dimension of less than 1 inch in the z'direction and the x direction, and is cut into a plate shape by AT cutting. Disconnect. After cutting, grind this, or wrap both sides or one side, and polish, etc., thickness of about 80 μm
The wafer 301 of about a certain size is formed. In addition to AT cut, there are Z cut, Y cut, SC cut, etc. SC cut is used for highly stable crystal units. FIG. 4B shows the formation of the protective film on the entire surface, and the protective film 302 and the protective film 303 are formed on the main surface 2 and the main surface 3 by sputtering as the protective films durable to the etching process. Cr is 200Å, A
u was formed at 2000Å. They may be formed simultaneously or separately. In addition to sputtering, vapor deposition such as electron beam or resistance heating may be used.

FIG. 4C shows the pattern formation of the protective film 302 and the etching process. The photolithography technique is used for forming the pattern of the protective film 302. Protect the resist 3
02, the resist film is exposed by sandwiching an exposure mask having a desired pattern, and the resist is developed and immersed in a solution in which the protective film is dissolved.
A pattern in which 05 is removed is formed. The protective film forming step is collectively referred to as patterning of the protective film 302 in FIGS. 4B and 4C. In the protective film forming step, the protective film 30 is formed in a pattern with the protective film removing portions 304 and 305 removed.
2 may be formed. For example, a sputtering mask having a window of the same pattern at the time of sputtering in FIG. 4B may be sandwiched between the metal source and the wafer 301 to perform sputtering. Although it is simple and requires few steps, the edges of the pattern are liable to blur, and it is better to use photolithography technology as in this example for more accurate dimension and stability. The front side main surface dimension 203, chamfer width dimension 204, and chamfer depth are stable. The dimension 310 can be secured.

The resist may be peeled off by a rim bar before or after the etching process of (c), and the protective film 3
02 and 303 may be peeled off after the etching process of (c) or after the cutting process of (d). In this example, the resist and the protective films 302 and 303 were separated after the etching process of (c). If it is carried out before cutting, it is possible to handle 50 crystal pieces 1 at the same time with good handling. In the etching process, the wafer 301 having the protective film 302 from which the protective film removing portions 304 and 305 have been removed and the protective film 303 formed on the entire main surface 3 is dipped in an etching solution to form the protective film 30.
The main surface 2 which is not covered with the Nos. 2 and 303 is melted to form the etching sections 307 and 308 at the same time. At this time, the etching portion 307 makes a part of the main surface 2 concave,
The thin plate portion 4 and the frame portion 5 are formed. Further, the chamfered portion 6 is formed. In this way, the wet etching process is a process of melting the etching portion 307 to form a concave shape in a part of the main surface 2 by the etching process of melting and processing the crystal. Quartz etching by dry etching is possible, but the etching rate is slow at 500Å / min, which is inferior to wet etching in terms of productivity. However, it is advantageous in terms of roughness after processing.

FIG. 4 (d) shows a cutting process in which a dicing saw cut along the cutting line 312. Although there is processing by a laser or the like, and processing by a cutter or the like, a dicing saw that has a proven cutting performance for separating a silicon wafer into IC chips is used, but a proven wire saw may be used for processing a crystal. In particular, the wire saw is effective when a plurality of wafers 301 are stacked and simultaneously cut. The wafer 301 is cut and processed in this way
The process of separating the crystal pieces 1 or more is referred to as a cutting process. The dicing saw was attached to the tape one by one, aligned with the reference line provided on the wafer 301, and cut at equal intervals from the reference line. The blade is rotated for processing, and water is applied to the processing points to cut at equal intervals. Wafer 301
Rotates along with the table and cuts in the x-axis direction and the z'-axis direction. By rotating, a reference line in the x direction and a reference line in the z'direction were provided on the main surface 3 of the wafer 301 after peeling the protective film 303 by a resist and photolithography process. This reference line is shown in Figure 5.
One of the cutting lines 312 in FIG. The end of the reference line formed by this resist is made to correspond to the cutting line 312.

The position of the reference line formed by the resist was determined by the marks formed at the same time as the etched portions 307 and 308 on the main surface 2 by etching. The exposure machine used was one that had the function of determining the front position using the mark on the back surface. The reference line is an important line that determines the positional relationship between the thin plate portion 4 and the contour of the crystal blank 1 in the cutting process by dicing.
That is, although the quartz piece 1 is to be formed as shown in FIG. 7A, the concave shape may be unidirectional as shown in FIG. 4D. A part of the protective film 303 may be used as the reference line, or the wafer 3 after the protective films 302 and 303 are peeled off.
Alternatively, the electrode 101 or the electrode 102 may be formed at 01 and a part of the electrode may be used or a dedicated mark may be formed. Cut surface 7
Cuts the main surface 3 almost perpendicularly while rotating the blade and irradiating it with water. By providing the chamfer 6,
It becomes difficult for chipping to occur at the boundary between the cut surface 7 and the chamfered portion 6, and it is possible to prevent cracks and variations in characteristics due to thermal shock. When the main surface 2 and the cut surface 7 are vertical as shown in FIG. 9, chipping is likely to occur. Further, when cutting into a matrix with a dicing saw, it is not necessary to take a wasteful area in the frame portion 602 and the penetrating portion 604 of FIG. 6, and the portions other than the crystal blank 1 are small and cost effective.

In FIG. 4 (e), dry etching is used to obtain an appropriate plate thickness 201 because it is necessary to oscillate at a desired resonance frequency. This is a step of uniformly thinning the entire main surface 3 to obtain a desired plate thickness 201, and obtaining the main surface 2 by dry etching. The reactive gas is used to reduce the plate thickness of the crystal blank 1. It is called a dry etching process. C in this example
H4 was used. At this time, wet etching or the like may be used in combination in order to efficiently maintain the flatness of the main surface. Although the plate thickness 201 may be adjusted by the etching process in FIG. 4C, the etching rate is usually high in the process by wet etching, and it is difficult to adjust the plate thickness of the fundamental wave oscillator of 100 MHz or more. Although the etching rate can be slowed down depending on the composition and temperature of the etching liquid, the surface roughness of the main surface 3 is greatly roughened under the condition that the etching rate is slowed down. The final etching of the plate thickness 201 by dry etching has an etching rate as slow as about 500Å / min, and processing is performed without roughening the surface as compared with wet etching. The frequency adjustment width by processing the electrode 101 or the electrode 102 is several hundred to several thousand Å
Since it is possible to adjust only the thickness of the electrode 102, which is finite and limited, it is necessary to adjust the plate thickness 201 within the frequency adjustment limit range of the electrode 102 in FIG. 4D. In this example, the frequency was measured for each crystal piece 1 first, the crystal pieces were sorted in the range of ± 300 ppm, and dry etching was performed simultaneously in units of 50 pieces. Converting the main surface 3 to frequency by dry etching, 165.00MHz ± 300p
It was adjusted with a plate thickness corresponding to pm.

FIG. 4F shows the formation of electrodes and the electrode formation process. After this step, it becomes a crystal vibrating element. After cleaning, an electrode is formed on the crystal piece 1 in a vacuum by sputtering. In addition, the electrode 101 is formed by forming a hole in the vapor deposition mask to form
It is a square with m angles. The electrode 102 is formed to have a dimension of 200 μm in the x direction and 300 μm in the z ′ direction by attaching a metal film on the entire main surface 3 once, forming a shape by a photolithography technique to ensure dimensional accuracy. Resonance frequency is 1 depending on the arrangement of electrodes
It becomes about 50.00MHz, and it is -300 from the target frequency.
It is within 0 ppm. The electrode 102 is rolled into the main surface 2. The electrodes 101 and 102 may be formed by vapor deposition such as electron beam or resistance heating vapor deposition. However, it was formed in as high a vacuum as possible. When the electrodes are formed by the photolithography technique, as shown in FIG.
When the metal layer is applied after the peeling of (c) and the electrode is formed by the photolithography technique, the position shift of the electrode 102 due to the unevenness of the resist and the twist of the crystal piece 1 due to the lack of the through portion 604 in FIG. 6 is prevented.

FIG. 4G shows the crystal piece 1 on the holder 405.
Is a process of fixing the electrode 102, processing the electrode 102 to adjust the resonance frequency, and further, assembling the holder 405 with a lid 410 for sealing. The crystal piece 1 is fixed to the holder 405 by using the support materials 406 and 408, but it has conductivity and serves to fix and to connect to the terminals 407 and 409. The electrode 102 is fixed by a supporting member 408 at a portion arranged on the main surface 2 which is wound, and further, is electrically connected to a terminal 409. The support materials 406 and 408 include conductive bumps, non-conductive bumps, conductive adhesives, and non-conductive adhesives. The electrode 102 does not squeeze in, but conducts by wire bonding or the like in a part on the main surface 3 that is drawn out so as to avoid from the area facing the electrode 101, and fixing is performed by using a non-conductive support material. You may use a means. This ensures conduction. Conduction means that they are electrically connected. On the other hand, the electrode 101 is fixed to the retainer 405 by the support material 406 at the portion drawn out so as to avoid the region facing the back electrode 102, and is electrically connected to the terminal 407. The holder 405 uses a ceramic package, and the lid is made of metal.

Frequency adjustment was performed after fixing the crystal piece 1 to the holder 405 and before sealing with the lid 410, and the electrode 102 was shaved with an ion gun. The processing of the electrodes for frequency adjustment includes an etching method of scraping the electrodes and a weighting method of weighting the electrodes. The etching method is performed by ion gun, laser, spatter, polishing, etc.
The resonance frequency of the main vibration is increased by scraping the electrode. In this example, after fixing to the holder 405 with Ar ions, the surface of the electrode 102 was shaved by an etching method using an ion gun. In the weighting method, the resonance frequency of the main vibration is lowered by laminating the back side electrode 102 on the electrode surface by sputtering, vapor deposition, coating or the like. Generally, Au, Al, etc. are laminated. The etching method is suitable for processing a small electrode. At this time, the resonance frequency is set to the terminal 407 and the terminal 4
09 is connected to a frequency measuring device such as a network analyzer to adjust the frequency while measuring the frequency. In this example, 150.
It was adjusted to ± 2 ppm of 0 MHz.

In this embodiment, the lid 410 is attached to the holder 40.
5 and voltage is applied in nitrogen, and the metal film arranged on the holder 405 and the lid 410 are welded and hermetically sealed. Cage 40
Reference numeral 5 is used to utilize the crystal vibrating element on the circuit while blocking the crystal vibrating element from the outside air. It is made of materials such as ceramics, piezoelectric materials, and metals. Ceramics are generally used in surface-mounted piezoelectric devices, and the piezoelectric material uses the same material as the piezoelectric device to prevent changes in resonance frequency due to temperature changes. Metal makes it easier to make the outer wall thinner, and it is easier to make a smaller package than ceramic. In this example, a ceramic SMD type retainer 405 is a two-layer laminated type in which a flat structure and a square shaped structure are laminated to form a concave structure, and the crystal vibrating element is housed in the concave structure. Outer terminal 40
In order to conduct electricity from the inside of the retainer 405, the conductors 7 and 409 are arranged by winding metal films before laminating the ceramics.

Besides, there is also a three-layer laminated type in which another plate is formed between the flat plate and the b-shaped plate and the crystal vibrating element is fixed here, and a single-layer type in which only the flat plate is formed. Since the three-layer laminated type has a space below the crystal vibrating element, an IC chip including an oscillation circuit is installed there and connected to the crystal vibrating element. When the piezoelectric body piece is a crystal piece, a crystal oscillator or a voltage A frequency-controlled crystal oscillator or a sensor for detecting acceleration due to frequency fluctuation may be added by adding the frequency variable function according to. A crystal oscillator or a voltage control type crystal oscillator is a reliable small surface-mount type piezoelectric device by taking advantage of the feature of the piezoelectric vibrating element of the present invention that the stability is increased. In this case, in addition to the terminals 407 and 409 on the outside of the package, it is necessary to provide a power supply voltage input terminal, an output terminal, a ground terminal, a frequency control input terminal and the like for connection with the IC chip. The lid 410 may be a flat plate type or a dome type, but may be selected depending on the cost and manufacturing method. Encapsulation in this example means fixing and sealing the piezoelectric vibrating element to a holder. Sealing with a lid is called sealing, and sealing methods include resistance welding sealing, glass sealing, solder sealing, and Au-Su sealing. The sealing agent is also determined according to the sealing method. Cage 405
The inside of the crystal oscillator is kept in an atmosphere of nitrogen or an inert gas, and is kept in a vacuum to prevent deterioration of the electrodes and the like, thus preventing the crystal oscillator from aging. The holder 405 and the lid 410 may be determined according to the sealing method, the internal atmosphere, and the cost.

Example 2 In FIG. 9, a concave shape is formed on a part of the main surface 2, and an electrode 101 and an electrode 102 are arranged facing each other on a thin plate portion 4 which is a concave thin portion. This is a piezoelectric vibrating element that obtains the main vibration and has a resonance frequency of the main vibration of 100 MHz. FIG. 10 is a sectional view thereof. A description will be given with reference to FIG. 8 focusing on FIGS. 9 and 10. As shown in FIG. 10, the thin plate portion 4 is sandwiched between the main surface 2 and the main surface 3 and has a plate thickness of about 17 μm. AT
In the cut, the frequency constant = thickness of the thin plate x main vibration frequency is shown, and it depends on the resonance frequency used.
Was changed to 17 μm at 100 MHz. A 0.5 inch wafer 301 is cut to form the outline of the crystal piece 1 and separated to obtain 30 pieces. 3 before cutting
Zero concave shapes were formed by thinning a part of the main surface 2 by etching processing by wet etching. In the cutting process, cutting is performed along a cutting line 312 that includes one concave shape at a time. As shown in FIG. 10, the thin plate portion 4 is a thin plate portion near the center of the crystal blank 1. The periphery of the thin plate portion also serves as the thick frame portion 5 having high strength, so that the main vibration is less likely to be affected by external force and the handling in manufacturing is improved. In this example, the thickness of the edge portion is 50 μm to 150 μm.
The concave-shaped inner side surface formed between the main surface 2 of the thin plate portion 4 and the main surface 2 of the frame portion 5 is not perpendicular to the main surface 2 due to anisotropy of crystal or undercut, and varies depending on the direction. Dimensions and slopes.

Since a plurality of concave shapes are formed on the wafer by etching and the contours of the crystal piece 1 are formed by cutting and separated, the concave shape and the contour are not formed at the same time. The main surface 2 of 402 is etched under optimum conditions, the control of the etching rate is facilitated, and the processing accuracy is improved. The dimensional accuracy and the roughness of the main surface of the thin plate are also improved. Furthermore, in comparison with forming the contour of the crystal blank 1 only by conventional wet etching,
The crystal pieces 1 are arranged in a matrix form adjacent to the wafer 301, and the number of the crystal pieces 1 is increased.

Further, in FIG. 8, in this example, the etching processing is performed with the pattern of the protective film 302 as shown in (q), but various crystal pieces 1 are formed with the patterns of the other protective films 302 and 303. Good. When chamfering the crystal piece to reduce the secondary vibration, the protective film removing portion 305 may be provided in the protective film 302, and the chamfered portion 6 is formed. Since the crystal piece 1 is chamfered by etching processing, the difficulty of processing does not change depending on the contour shape of the crystal piece 1 compared to the conventional chamfering processing, and it is not necessary to individually process the crystal piece 1 for production. Good sex. Further, the chamfered portion 6 prevents chipping or the like that is likely to occur when the crystal blank 1 is cut by cutting.

In FIG. 9, the frame portion 5 is the thin plate portion 4 in the axial direction.
Existing in three directions, but may be three directions, two directions, or one direction, and the protective film removing portion 30 at the place where the concave shape is formed
The pattern of the protective film 302 and the cutting line 312 according to the dimension of 4
Determined by It is fixed by the frame portion 5 of the piezoelectric vibrating element to avoid instability of characteristics due to distortion due to external force or the like. Three
The piezoelectric vibrating element having edges in one direction and one direction is stronger in strength than the piezoelectric vibrating element composed of only the thin plate portion 4, and when it is fixed to the cage only on one side, it has an effective shape that can alleviate thermal strain. . The crystal vibrating element of FIG. 10 is enclosed in a holder 504 and used as a crystal resonator which is a piezoelectric device.

The main vibration is obtained by arranging the electrode 101 on the main surface 2 of the thin plate portion 4 and the electrode 102 on the main surface 3 so as to face each other. The main vibration is the thickness shear vibration in this example, especially the fundamental wave vibration of the thickness shear vibration, but overtone may be used, and it is possible to realize a higher frequency than the conventional flat plate type crystal resonator. . In this example, the electrode 102 has a larger area than the electrode 101, but since the electrical characteristics are affected by the electrode having a smaller area, the electrode 1 that can be originally formed with high accuracy.
It is better to reduce the area of 02 by forming it with high precision by using a photolithography technique or the like. However, in the case where the electrode 102 is formed after the main surface 3 is scraped and the plate thickness is adjusted, the area of the electrode 101 is reduced to measure accurate electrical characteristics before and after the plate thickness adjustment and classify the defects. Is possible.

(Embodiment 3) In FIG. 2, the thin plate portion is deformed by the external force applied to the crystal piece 1 to change the resonance frequency of the crystal vibrating element and detect that the external force is applied. Thin plate part 4
Means the concave bottom portion in FIG. In order to improve the strength and to favorably support the thin plate portion 4, there is provided a frame portion 5 in which the plate thickness of the outer periphery is thicker than that of the thin plate portion. In order to stabilize the characteristics of the sensor, it is necessary to adjust the resonance frequency constant. Further, when the thin plate portion is thinned to enhance the sensitivity, the electrode 101 is formed on almost the entire main surface 2 and the concave inner side surface.
By arranging, the strength may be reinforced and the thickness of the metal film may be adjusted to prevent the hypersensitive response due to an external force.

In FIG. 2, since the exposure mask for electrode formation can be brought close to the main surface 3, the electrode 102 can form an electrode with a more accurate size than the concave main surface 2 of the bottom. When utilizing the confinement effect of vibrational energy,
Since the characteristics of the crystal resonator are mainly influenced by the small electrodes, the electrodes having a smaller area than the main surface 2 are formed on the main surface 3 with high accuracy to form a crystal vibrating element having stable characteristics.
In particular, it is necessary to have a complicated shape in order to efficiently collect the charges generated in the crystal blank 1, and the processing accuracy at the time of electrode formation is also important. At this time, in order to avoid unnecessary vibration, or a part of the electrode 102 may be left unprocessed as a mass point that is easily affected by inertial force. In FIG. 4, the quartz piece 1 was cut from the wafer 301 and separated to finally form the quartz resonator element. Prior to the cutting process, a plurality of concave shapes were formed on the wafer 301 by wet etching to form the electrodes 102. In order to finely adjust the plate thickness and adjust it accurately, the main surface 2 was processed by dry etching to make the thin plate portion 4 thinner. Further, an electrode 101 was formed, and for frequency adjustment, the electrode 102 was evenly ground with an ion gun. By manufacturing the quartz piece 1 without separating it in more steps, it is possible to handle the quartz piece 1 with good handling, adjusting the plate thickness, cleaning,
Resist stripping, protective film stripping, various inspections, and the like can be efficiently processed, and electrodes 101 and 102 are efficiently formed at the same time. Since the electrodes 102 are formed by the photolithography technique in the state of the wafer 301 having no through holes, the resist irregularities are small, and the electrodes can be accurately formed without distortion of the wafer 301 during exposure.

In FIG. 4, a holder 405 is a thin surface mount type container that takes out the detected frequency fluctuation information while hermetically sealing it. The electrode 101 is installed toward the holder 405. The holder 405 includes a terminal for external power supply and terminals 407 and 409 for outputting a sensor signal, and may further include a terminal for grounding, a terminal for external control, and the like.
The material is a ceramic SMD package, and an IC chip may be housed under the piezoelectric vibration element. When the IC chip is housed, an oscillation circuit of the piezoelectric vibration element and a circuit for calculating the difference between the resonance frequency changed by an external force and the normal resonance frequency are arranged.

In FIG. 3, A created by machining
Protective films 302 and 303 are formed on a T-cut wafer 301, and a pattern is formed by a photolithography technique. By immersing the wafer 301 on which the protective films 302 and 303 are formed in the pattern as shown in FIG.
To form a concave shape. At this time, the chamfered portion 6 is simultaneously formed by melting the etching portion 308. Chamfer 6
Is formed so as to surround the thin plate portion 402 as shown in FIG. However, the removal width dimension 306 is adjusted and the chamfered portion width dimension 204 and the chamfered portion depth dimension 310 are determined so that the wafer 301 does not warp in a later process and maintains sufficient strength. A cutting line 312 is set in the vicinity of the etching portion 308, and cutting processing is performed to form the cutting surface 7, and the quartz piece 1
To form the contours of and separate into individual. The wafer 301 is subjected to batch processing for adjusting the plate thickness, forming electrodes, and adjusting the frequency. This provides better handling than handling smaller piezoelectric vibrating elements individually.

The piezoelectric vibrating element is an element for arranging an electrode on a piezoelectric piece cut into a predetermined geometrical shape, size and angle with respect to a crystal axis to apply an electric charge to obtain vibration.
A piezoelectric vibration element is enclosed in a holder and used as a piezoelectric device. Mainly used are vibrators, oscillators, and sensors that use quartz, langasite, or lithium niobate for piezoelectric pieces. In crystal, a piezoelectric piece is a crystal piece, a piezoelectric vibrating element is an element composed of a crystal piece and an electrode, a piezoelectric device is a crystal oscillator, a crystal oscillator, a sensor, etc.
It is a crystal piece such as cut, Z cut, or SC cut. The outline of the piezoelectric piece viewed from the main surface includes a quadrangle, a triangle, and a circle. In this example, a thin plate portion of which a part of the main surface is thin, a piezoelectric piece composed of a frame portion having a large plate thickness excluding the part, and electrodes arranged on both main surfaces of the thin plate part are provided. The piezoelectric vibrating element has a concave piezoelectric vibrating element having a concave shape on the main surface. In the piezoelectric piece of this example, a part of the thickness of a wafer on which two or more piezoelectric pieces are taken is thinly etched by using at least one of wet etching and dry etching, and The wafer was cut and separated using either one of a dicing saw and a wire saw to form the wafer. A part is a region where a thin plate portion is formed by forming a concave shape. Further, the chamfered portion may be formed by chamfering the edge of at least one of the main surfaces by etching at the same time in the vicinity of a cutting line to be cut later by cutting by etching. The concave shape may be in contact with the contour of the piezoelectric piece or may be formed by shifting in one direction. A concave shape may be formed on both main surfaces. The thin plate portion, which is the bottom of the concave shape, may be subjected to etching processing by wet etching and then the thickness thereof may be adjusted again by dry etching.
Even if the chamfered portion is not formed, it is formed on one main surface or both main surfaces and determined by the pattern of the protective film. The width dimension and the depth dimension of the chamfer of the chamfer are adjusted by the pattern of the protective film according to the dimension of removing the protective film. The electrode may be formed of Au, Ag, Al, Cr, or Ni or an alloy thereof, and may be layered.

[0051]

According to the present invention, it is possible to realize a piezoelectric vibrating element which is excellent in dimensional accuracy and surface roughness of the main surface, and has stable characteristics against secondary vibration. Furthermore, the production efficiency of the chamfering process is ensured, and a method for manufacturing the above-described piezoelectric vibration element is provided. Chamfering is performed with free dimensions to reduce side vibrations and adjust the resonance frequency of side vibrations arbitrarily to further secure or adjust the strength of the wafer. By manufacturing the piezoelectric vibrating element using the manufacturing method of the present invention, the following unique effects are exhibited as compared with the case of manufacturing the piezoelectric vibrating element without using the manufacturing method of the present invention. That is, since the piezoelectric piece is not deformed due to contact exposure or unevenness of the resist, positional deviation and dimensional deviation are prevented, and electrodes are accurately formed. By dividing the formation of the concave shape by the etching processing and the formation of the outline of the piezoelectric piece by the cutting processing, the processing can be performed under the conditions optimized for the wet etching for reducing the plate thickness, and the surface roughness is improved. In addition, the number of picked-up pieces increases and the productivity improves.

[Brief description of drawings]

FIG. 1 is an example of a piezoelectric vibration element of the present invention.

FIG. 2 is a cross-sectional view of the piezoelectric vibration element of the present invention.

FIG. 3 is a cross-sectional view in the wet etching process of the present invention.

FIG. 4 is an example of a procedure for manufacturing the piezoelectric device of the present invention.

FIG. 5 is an example of a manufacturing procedure of the piezoelectric vibration element of the present invention.

FIG. 6 is an example of a manufacturing procedure by conventional wet etching.

FIG. 7 is a cross-sectional view of the piezoelectric vibration element of the present invention.

FIG. 8 is a pattern example of a protective film of the present invention.

FIG. 9 is an example of the piezoelectric vibration element of the present invention.

FIG. 10 is a cross-sectional view of the piezoelectric vibration element of the present invention.

FIG. 11 is an example of vibration modes of a main vibration and a sub vibration of the present invention.

[Explanation of symbols] 1 crystal piece 2 main surface 3 main faces 4 Thin plate 5 frame 6 chamfer 7 cut surface 101 electrode 102 electrodes 201 plate thickness 202 Back side main surface dimensions 203 Front side main surface dimension 204 chamfer width dimension 301 wafer 302 Protective film 303 protective film 304 Protective film removal section 305 Protective film removal section 306 Width of removed part 307 Etching part 308 Etching part 309 Width of etching area 310 Chamfer depth 311 Undercut part 312 cutting line 401 thin plate 402 frame 403 Dry etching part 404 filling atmosphere 405 cage 406 Support material 407 terminal 408 Support material 409 terminal 410 lid 601 connection 602 frame part 603 Protective film removal section 604 Penetration part 801 Etching part 802 Protection film removal section 901 plus area 902 Minus area

Claims (12)

[Claims] 1. A thin plate part having a thinned part of the main surface,
A piezoelectric piece composed of a thick frame portion excluding the part,
In a piezoelectric vibrating element having electrodes arranged on both main surfaces of the thin plate portion, the piezoelectric piece is a part of a wafer on which two or more piezoelectric pieces are taken, and the thickness of The piezoelectric vibrating element is characterized in that after the etching processing is performed by using at least one of the above, the wafer is cut by using one of a dicing saw and a wire saw and separated. . 2. A thin plate portion in which a part of the main surface is thinned,
A piezoelectric piece composed of a thick frame portion excluding the part,
In a piezoelectric vibrating element having electrodes arranged on both main surfaces of the thin plate portion, the piezoelectric piece is a part of a wafer on which two or more piezoelectric pieces are taken, and the thickness of After being etched to be thin by using at least one of the above, the wafer is cut and separated using one of a dicing saw and a wire saw, and at least the main body after the etching. A piezoelectric vibrating element, wherein the thin plate portion is formed by adjusting a plate thickness of a part of the surface by dry etching so as to be thin. 3. The piezoelectric piece has a chamfered portion in which at least one main surface is chamfered at the same time by the etching processing in the vicinity of a cutting line to be cut by the cutting processing at the same time. The piezoelectric vibrating element according to claim 1 or 2, which is characterized. 4. The piezoelectric piece according to claim 1, wherein the size of the back main surface which is the size of one main surface is larger than the size of the front main surface which is the size of the other main surface. Two
2. The piezoelectric vibrating element according to. 5. The AT-cut crystal piece utilizing the thickness shear vibration, wherein the piezoelectric piece is an AT-cut crystal piece.
Alternatively, the piezoelectric vibration element according to claim 2. 6. The piezoelectric vibrating element according to any one of claims 1 to 5 is filled with nitrogen or an inert gas,
Alternatively, a piezoelectric device that is evacuated and sealed in a sealed container. 7. A thin plate part having a thinned part of the main surface,
A piezoelectric piece composed of a thick frame portion excluding the part,
In a method for manufacturing a piezoelectric vibrating element having electrodes arranged on both main surfaces of the thin plate portion, a wafer forming step of forming a wafer by machining, and a part of one main surface of the wafer formed in the wafer forming step Except for the protective film forming step of forming a protective film having durability against etching processing,
A wet etching step of thinly etching at least a part of the plate thickness, and a wafer after the wet etching step is cut and separated using one of a dicing saw and a wire saw to separate the outline of the crystal piece. A method of manufacturing a piezoelectric vibrating element, comprising: 8. A thin plate part having a thinned part of the main surface,
A piezoelectric piece composed of a thick frame portion excluding the part,
In a method for manufacturing a piezoelectric vibrating element having electrodes arranged on both main surfaces of the thin plate portion, a wafer forming step of forming a wafer by machining, and a part of one main surface of the wafer formed in the wafer forming step Except for the protective film forming step of forming a protective film having durability against etching processing,
A wet etching step of thinly etching at least a part of the plate thickness, and a wafer after the wet etching step is cut and separated using one of a dicing saw and a wire saw to separate the outline of the crystal piece. And a dry etching step of forming the thin plate portion by further adjusting the plate thickness of the part etched in the wet etching step to form the thin plate portion. Manufacturing method. 9. The protective film forming step is characterized in that a protective film is formed on the entire surface of at least one main surface, and a part of the protective film is removed by using a photolithography technique. Alternatively, the method for manufacturing a piezoelectric vibrating element according to claim 8. 10. The dry etching process according to claim 8, wherein the plate thickness of the part formed by etching in the wet etching process is 10 μm or less thicker than the plate thickness of the thin plate portion. A method for manufacturing a piezoelectric vibrating element according to claim 1. 11. The protective film forming step does not form a protective film near a cutting line to be cut in the cutting processing step,
11. The wet etching step includes etching the vicinity of the cutting line to form a chamfer by chamfering an edge of at least one main surface of the piezoelectric piece. A method for manufacturing the piezoelectric vibrating element according to any one of the above. 12. The chamfered portion is formed by adjusting at least one of a chamfer width and a chamfer depth by a pattern of the protective film in the protective film forming step. 7. A method for manufacturing a piezoelectric vibrating element according to.