JPH08181558A - Piezoelectric element, piezoelectric vibrator, their manufacture and machining device unit - Google Patents

Abstract

PURPOSE: To realize an inexpensive piezoelectric element and a piezoelectric vibrator whose performance is made stable by connecting a measurement means measuring frequency to an electrode of the piezoelectric via a connection means to eliminate a DC or a low frequency component such as a pule wave so as to attain accurate frequency adjustment with plasma processing. CONSTITUTION: A frequency adjustment source 9 is used to measure a resonance frequency of a piezoelectric element 3 with a network analyzer 1 continuously via a fixture 2. Furthermore, a distance between a work 3 and the block frequency adjustment source (ion gun) 9 is adjusted by a drive mechanism 14. Thus, the processing rate of the block is changed. Thus, the a frequency difference between a frequency of the work 3 and a frequency to be matched is controlled by an external arithmetic unit 15 for each block and a control signal is fed to the device 14 so that an optimum processing rate of the block is obtained and the distance between the work 3 and the adjustment source 9 is changed for each block. As a result, the frequency of the work 3 is adjusted stably till the frequency reaches a target frequency.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for adjusting the resonance frequency in the process of manufacturing a piezoelectric element such as a crystal resonator, a device therefor, and a piezoelectric element and a resonator manufactured by these methods.

[0002]

2. Description of the Related Art A conventional frequency adjusting method using vapor deposition to obtain a desired frequency by adding mass is generally used for adjusting the frequency of a piezoelectric element represented by a conventional crystal resonator. On the other hand, in recent years, a frequency adjustment method using so-called plasma has been proposed, in which sputter etching is performed or an ion beam is used to irradiate an ion beam to reduce the mass of an electrode to obtain a desired frequency.

In the current frequency adjusting method using plasma, first, the piezoelectric base material is cut into a predetermined cutting angle and shape, and then polished to finish the piezoelectric body. Then, a mask imitating the shape of an electrode is brought into close contact with the front and back of the piezoelectric body, and then a metal film of silver or the like is deposited in vacuum to form a base electrode. At this time, unlike the conventional frequency adjustment by vapor deposition,
The frequency during vapor deposition is controlled by the film thickness monitor, and the resonance frequency is set 500 to 2000 ppm lower than the desired value. That is, the element is manufactured in a state where the film thickness is increased with respect to the electrode film thickness at which a desired frequency is obtained.

The piezoelectric element having such electrodes is mounted on an appropriate holder and sputter etching or ion beam irradiation is performed to reduce the thickness of the electrodes to increase the frequency and obtain a desired resonance frequency. When performing such frequency adjustment, first, the resonance frequency of the piezoelectric element (workpiece) to be adjusted is measured to obtain the frequency difference from the fitting frequency. The processing rate for adjusting the frequency of the piezoelectric element is determined based on the intensity of the sputter etching or the ion beam measured in advance, and the time for which the sputter etching or the ion beam is irradiated is calculated from the frequency difference between individual works and this processing rate.

Next, irradiation is started based on this irradiation time. During irradiation, a direct current flows through the work, so the measurement system is electrically disconnected. Then, before reaching the calculated irradiation time, the irradiation is interrupted, the measurement system is reconnected, the resonance frequency of the work is measured again, and the difference from the fitting frequency is detected. By repeating these operations several times, the difference from the tuning frequency is within the specified range (almost zero).
Align so that

In the frequency adjusting method using vapor deposition, the vapor deposition rate must be extremely slowed down when the frequency is adjusted, and a mask for limiting the vapor deposition portion must be highly accurate. In terms of equipment, working time, etc., the cost was very high. Moreover, the frequency accuracy after adjustment could not be so high. On the other hand, the frequency adjusting method using plasma has the advantage that the working time is short and the frequency accuracy after adjustment is high.

[0007]

However, the proposed frequency adjusting method using plasma also has some problems to be solved. First, unlike the case of vapor deposition, a direct current flows through the work by applying plasma, so that the resonance frequency during frequency adjustment cannot be monitored. Therefore, the irradiation time must be determined from the processing rate, and the frequency must be adjusted by managing this time. The processing rate that determines the irradiation time can be calculated in consideration of various factors such as the size and type of electrodes, but there are individual differences in the manufacturing process for each piezoelectric element even in the same frequency band, or the sputtering gun There are various factors that affect the processing rate, such as the stability of the source side of the ion beam gun and the atmosphere of the processing equipment. And it is very difficult to manage these all at once. In this way, if the irradiation time is simply managed, the resonance frequency after frequency adjustment will deviate from the adjustment frequency. Therefore, the irradiation time is divided and the irradiation time is adjusted according to the adjustment situation. Therefore, in practice, the steps of irradiation, frequency measurement, and irradiation need to be repeated many times, so that the effect of shortening the processing time has not been obtained so much. In addition, since only the irradiation time is managed, advanced experience is required to finally match the frequency and ensure high accuracy, and automation is difficult.

Next, there is a problem of processing rate. If the voltage and current applied to the sputtering or ion gun are kept constant, irradiation with a substantially constant and stable energy can be obtained, and the processing rate can also be kept substantially constant. However, when there is a large difference between the resonance frequency of the workpiece and the combined frequency, the machining time becomes long and the manufacturing efficiency deteriorates unless a large machining rate is obtained. On the other hand, when finely adjusting the frequency, highly precise adjustment cannot be made unless the processing rate is small. Although the machining rate can be increased and a certain degree of accuracy can be ensured by a mechanism such as a shutter, the machining apparatus becomes complicated and there is a problem to be taken into consideration such as stability of control and operation thereof. Further, even if such a mechanism is used, improvement in final frequency accuracy cannot be expected so much.

It is also possible to adjust the processing rate by controlling the current supplied to the frequency adjusting source such as the ion gun. However, if the processing rate changes, the processing time also changes, and unless the fluctuation of the energy of the ionized particles can be grasped with high accuracy, the processing time with high accuracy cannot be set. Therefore, since it is not possible to monitor the resonance frequency described above, it is difficult to secure the final frequency accuracy even if the processing rate is changed and the processing time can be shortened. Further, in order to maintain the frequency adjustment source in a steady state, it is necessary to supply electric power above a certain level, and it is also necessary to solve the instability of the frequency adjustment source due to the fluctuation of the electric power.

The frequency adjusting method in which the thickness of the electrode is reduced by using the plasma as described above is expected to be very advantageous in terms of improvement in accuracy and shortening of processing time, but a product having stable performance can be manufactured at low cost. Not yet available.
Therefore, an object of the present invention is to solve the above problems and provide a manufacturing method capable of actually supplying a piezoelectric element whose frequency is adjusted by plasma to the market, and a processing apparatus suitable for the manufacturing method. Further, another object of the present invention is to provide a manufacturing method and a processing apparatus in which the frequency adjustment by plasma is made inline in the manufacturing process so that the frequency can be adjusted efficiently. It is an object of the present invention to provide a piezoelectric element and a vibrator, the frequency of which is precisely adjusted by plasma processing using such a manufacturing method and a processing apparatus, and whose performance is stable, at low cost.

[0011]

In the present invention, first, in order to improve the accuracy of frequency matching, measuring means such as a network analyzer for measuring frequency is used to remove low frequency components such as direct current and pulsating current. The piezoelectric element is connected to the electrode of the piezoelectric element via the connecting means so that the change of the resonance frequency during irradiation can be monitored. As a connecting means capable of removing low frequency components, a coil connected to the ground side can be used, whereby components that are unnecessary for monitoring the resonance frequency, such as direct current components flowing by irradiation, are removed, and the measurement system You can avoid damage. By adjusting the frequency while monitoring the resonance frequency, continuous processing is possible and further automation is easy, so the process of adjusting the frequency is also incorporated into the automated manufacturing process for efficient operation. Can be done. Furthermore, by connecting a load capacitance in addition to the coil, in addition to the filter function, matching with the piezoelectric vibrator user's circuit system can be achieved, and by connecting a resistor in series with the coil, the initial irradiation The current can be reduced.

In the present invention, a means for controlling the distance between the irradiation means and the electrode to be irradiated is provided so that the irradiation intensity of the ionized gas such as an ion gun can be controlled in a stable state. There is. By changing the distance between the irradiation means and the electrode, the energy of the ionized gas with which the electrode is irradiated can be controlled without changing the operating state of the irradiation source. Therefore, it is possible to adjust the frequency with high accuracy under stable irradiation conditions.

Further, in the present invention, by performing irradiation in a plurality of steps, the time required for processing work is shortened and a highly accurate resonance frequency is obtained. That is, by combining a process having a relatively high processing rate and a process having a relatively low processing rate, it is possible to shorten the processing time and finely adjust the resonance frequency. In addition, by dividing the process in this way,
Since the turndown ratio (ratio between the maximum value and the minimum value of the processing rate) in one process can be reduced, the stability of the device can be increased, the device can be simplified, and the reliability can be improved.

[0014]

FIG. 1 shows an example of a processing apparatus for adjusting the frequency of a piezoelectric element according to an embodiment of the present invention. The device 30 of this example is mainly divided into three blocks along the moving direction (arrow A) of the transfer mechanism 18 such as a conveyor that transfers the piezoelectric element. The first block 31a on the side where the piezoelectric element is introduced is a block for rough adjustment that roughly adjusts the frequency of the piezoelectric element. The next second block 31b is
It is a block for coarse and fine adjustment that performs intermediate frequency adjustment,
Following this, a third block 31c for arranging the final frequency is arranged.

In each of the blocks 31a to 31c, the ionized gas from the frequency adjusting sources 9a to 9c having different irradiation energy is applied to the piezoelectric element (work) 3 carried by the carrier mechanism 18. In this example, ion guns are used as the frequency adjustment sources 9a to 9c, and argon gas is used as the gas. The ion guns 9 a to 9 c, the work 3 and the transfer mechanism 18, and a mechanism for adjusting their positions described later are housed in the vacuum container 10. This vacuum container 10
After being evacuated to about 10 ^-3 Torr by a rotary pump 12 via a mechanical booster pump 11, the inside of the argon gas source 8 to 10 ^-1 to 10 ^-2 To
The argon gas is filled up to about rr. further,
Load lock chambers 10a and 10b are provided on the carry-in side and carry-out side of the vacuum container 10, and the work 3 is continuously carried into the vacuum container 10 by using the carrying mechanism 18.

The work 3 carried in by the carrying mechanism 18 is irradiated in order from the first block 31a to the second and third blocks 31b and 31c, and the frequency is automatically adjusted. Before the work 3 is carried into the processing apparatus 10, metal electrodes such as silver and aluminum are formed on the surface of the piezoelectric body by vapor deposition or the like, and these electrodes have a desired resonance frequency f0. The electrode is made slightly thicker. Therefore, the resonance frequency f1 of the loaded work 3 is 2000 p with respect to the desired resonance frequency f0.
The value is as low as about pm, and the apparatus 30 of this example performs processing for irradiating such a work with ion gas to reduce the thickness of the electrode and increasing the resonance frequency f1 to f0.

Since the frequency f1 of the work 3 in which the electrode serving as the base is finished has a variation of about 2000 ppm, first, the first block 31 for performing rough adjustment is used.
In a, it takes charge of adjusting up to 200 ppm with respect to the desired resonance frequency f0. Therefore, the distance between the work 3 and the frequency adjusting source 9a is set to about 5 mm, which is closer to the frequency adjusting sources of the other blocks, and thus the processing rate is as fast as about 800 ppm / sec. .

In the second block 31b, coarse and fine adjustments are made,
It takes charge of the adjustment until the frequency f1 of the workpiece 3 in the coarse adjustment is about 50 ppm with respect to the resonance frequency f0. Therefore, the distance between the work 3 and the frequency adjustment source 9b is set to about 10 mm, and the machining rate is about 100.
ppm / sec can be obtained.

The third block 31c is a block for performing final adjustment, that is, fine adjustment, and the frequency f1 of the coarse and finely adjusted work 3 is 0 ppm with respect to the desired resonance frequency f0.
It takes charge of the adjustment until it becomes. For this reason, the distance between the work 3 and the frequency adjustment source 9c is set to about 20 mm, and the processing rate can be adjusted slowly so that a slow processing rate of about 20 ppm / sec can be obtained.

The processing apparatus 30 of the present example can adjust the frequency from 2000 ppm to 0 ppm in a short time by performing the frequency adjustment in such three steps having different processing rates, and also makes the final fine adjustment. It's easy to do. And these blocks 31a
Since the work is automatically conveyed between the spaces 31c to 31c, the work 3 can be continuously processed, and the step of adjusting the frequency can be easily introduced into the flow of the manufacturing process.

The frequency adjusting sources 9a to 9c can individually measure the resonance frequency f1 of the piezoelectric element 3 continuously with the network analyzer 1 via the fixture 2. Further, the frequency adjustment source (ion gun) 9a of each block
The distance between ~ 9c and the work 3 can be adjusted by the drive mechanisms 14a to 14c, whereby the machining rate of each block can be changed. Therefore, the frequency f of the work
The frequency difference Δf between 1 and the combined frequency f0 is managed by the external arithmetic unit 15 for each block, and a control signal is sent to each drive unit 14 so as to obtain the optimum machining rate of that block, and the work is performed for each block. 3 and frequency adjustment source 9a
The distance to ~ 9c can be changed. As a result, in each block, the frequency f1 of the work 3 can be adjusted easily and surely until it reaches the target frequency. Furthermore, the apparatus 30 of the present example can prevent the situation where the frequency adjustment fails due to excessive irradiation without lowering the processing speed.

FIG. 2 shows the configuration of each of the first to third blocks. The configuration of these blocks 31a to 31c is the same except for the distance between the work and the ion gun, the irradiation energy of the ion gun, and the like, so one block is shown as a representative.

In this example, the ion gun 9 is used as a frequency adjusting means, that is, a frequency adjusting source installed inside the vacuum container 10. The ion gun 9 includes, for example, a stainless steel φ10 mm electrode rod to which a DC power source 13 is connected, is insulated from the φ100 mm cylindrical stainless steel forming the outer peripheral portion, and further the outer peripheral portion is grounded. It is shielded. As described above, the vacuum container 10 is evacuated to the level of 10 ^-3 Torr, and then argon gas is introduced into the electrode rod of the ion gun 9 from the DC power supply 13 in the state of being supplied with about 10 ^-1 to 10 ^-2 Torr. When a DC voltage is applied, argon plasma is generated between the earth shielded outer peripheral portion. The generated plasma turns the argon gas into radicals and ions, and the ionized argon gas is ejected from the φ3 mm ejection port 5 of the ion gun 9 that strikes the tip of the electrode rod.

The work 3 transported by the transport mechanism 18 is located at a position opposed to the ejection port 5, and the ionized gas particles collide with the surface of the work 3 such as a crystal oscillator. The electrode film 4 formed on the surface of the work 3 by the collision of the argon ions with the work 3 (in this example, the electrode films 4a and 4b are formed on both surfaces of the work 3, and the argon ion is the electrode film shown in the figure). 4a), which irradiates the electrode film 4b on the surface opposite to 4a), is flipped away. Therefore, the mass of the electrode is reduced, and as a result, the frequency f1 of the work 3 changes from a low frequency to a high frequency.

A shutter 16 is installed between the ion gun 9 and the work 3, and the irradiation of argon ions can be blocked by controlling the opening and closing of the shutter 16 by a driving mechanism 17. Further, a mask 25 is inserted between the shutter 16 and the work 3, and the mask 25 defines the directionality of argon ions.
The mask 25 used in the apparatus of this example is intended to prevent the argon ions from being irradiated to the plurality of works 3 that are continuously conveyed, except for the works whose frequency is adjusted. . Therefore, it is not necessary to use a highly accurate mask such as a mask used for vapor deposition, and the positioning of the workpiece with respect to this mask does not require so much accuracy.

Further, a driving mechanism 14 for moving the ion gun 9 in the front-back direction with respect to the work 3 is provided, and by changing the distance between the ion gun 9 and the work 3, the energy of the argon ions irradiated on the work. And the amount can be controlled. By controlling the energy and amount of argon ions by changing the distance in this way, the ion gun 9 can be held in a stable state with a predetermined electric power applied, so that stable performance and processing rate can be obtained. Therefore, the processing rate can be easily controlled, the high rate can be controlled while a large amount of electric power is applied, and the good responsiveness can be obtained at the low rate for performing fine adjustment.

The frequency f1 of the work 3 which changes due to the collision of argon ions is passed through the fixture 2 to the frequency measuring means, that is, the network analyzer 1.
Are continuously measured. For connection between the network analyzer 1 and the fixture 2, a 50Ω coaxial cable is used. The connection between fixture 2 and the work is
The frequency of the lead connected to the work 3 is measured by the drive mechanism 24 via the detachable probe 23, and the frequency of the continuously conveyed work 3 during irradiation is measured.

FIG. 3 shows the configuration of the measurement system used in the apparatus of this example. In the circuit configuration (impedance matching circuit) of the fixture 2 used in the measurement system of this example, the resistors 19, 20, and 21 are arranged in a π type on each of the two electrodes 4a and 4b provided on the work 3. The standard π circuits described above are connected, and further, the coil 22 is connected upstream of these π circuits (on the side of the work 3) in parallel with the resistor 21. These coils 22 are connected to the circuit so as to short-circuit the electrodes 4a and 4b of the work 3 and the ground. For this reason, the electrodes 4
The positive charges charged on a and 4b flow to the ground through the probe 23 and these coils 22 as a DC component or a low frequency component, and do not flow to the network analyzer side. Therefore, only the AC component due to the resonance frequency flows into the network analyzer 1. Therefore, even if a large low-frequency component current flows through the work 3 due to irradiation, this low-frequency component that causes a failure does not flow into the network analyzer side, and the frequency can be continuously monitored even during irradiation. It will be possible.

4 to 6 show examples of circuits having different fixtures. The example shown in FIG. 4 uses a simple matching circuit, and includes a coil 22 that bypasses a low frequency component, and an impedance matching resistor 21 that is connected in parallel with the coil 22. Resistance 21
Is selected to have a value higher than the impedance of the coil 22, so that the low frequency component flows into the coil 22 and only the high frequency component is supplied to the network analyzer side.

The example shown in FIG. 5 is a circuit in which a load capacitance 26 is added to the coil 22 in addition to the standard π circuit. As the value of the load capacitance 26, a value actually incorporated in the oscillation circuit by the user can be adopted, and the resonance frequency can be measured under the same conditions as those measured at the supply destination. Furthermore, since the load capacitance 26 also functions as a filter that passes only high-frequency components to the network analyzer side, it has a function of dropping low-frequency components such as direct current to the ground side without passing the coil 22 and the network analyzer side to the ground side. There is. It is also possible to add load capacitance to the simplified matching circuit shown in FIG.

In the example shown in FIG. 6, a resistor 27 is connected in series with the coil 22 in addition to the load capacitance 26 in the simplified matching circuit shown in FIG. The current flowing through the coil 22 can be limited by connecting the resistor 27 in series with the coil 22. A large DC current suddenly flows through the electrodes at the start of irradiation, but by inserting the resistor 27, it is possible to limit the value of this inrush current and adjust the current flowing through the piezoelectric element. Any of these circuits can be adopted as a circuit forming the fixture 2, and an appropriate circuit may be selected in consideration of factors such as the shape and type of the piezoelectric element and the irradiation state.

Returning to FIG. 3, an outline of the network analyzer 1 used for monitoring the resonance frequency in this example will be described. Network analyzer 1
Is provided with a high-frequency generation source 41, and the generated high-frequency signal is separated into two by a signal separation unit 42, one of which is applied to one of the electrodes of the work 3 via the input side of the fixture 2. It The other side of the electrode of the work 3 is input to the receiving unit 43 of the network analyzer 1 via the output side of the fixture 2, and the signal separating unit 4 is input to the receiving unit 43.
The remaining signals separated by 2 are also input at the same time. Then, the phase and amplitude ratio of these high frequency signals are obtained by the receiving unit 43, and the resonance frequency of the work 3 displayed on the display unit 44 and being adjusted in frequency is monitored. At the same time, these pieces of information are supplied to the external arithmetic unit 15, and the resonance frequency f1 monitored and the preset matching frequency f0 or the frequencies f0 ″, f0 ′ targeted in the first or second block are set. And are compared.

The external arithmetic processing unit 15 calculates the optimum machining rate for machining the workpiece in each block based on these comparisons. Further, in order to obtain the calculated machining rate, the distance between the work 3 and the ejection port 5 of the ion gun 9 is calculated, and a signal is sent to the drive unit 14. As a result, the frequency adjustment source 9 moves back and forth, and the distance between the ejection port 5 and the work 3 is adjusted appropriately.

The resonance frequency f1 of the workpiece 3 during irradiation can be monitored by using an oscillator 45 and a frequency counter 46 shown in FIG. 7 instead of such a network analyzer. Then, by supplying the output of the frequency counter 45 to the external arithmetic processing unit 15, the processing rate can be controlled in the same manner as described above.

The distance between the work 3 and the ejection port 5 of each block is adjusted using the resonance frequency f1 monitored by these devices. The apparatus of this example has a mechanism in which this distance can be varied from 5 to 20 mm for each block, and is preset to a distance of 5 mm before starting frequency adjustment processing. When the processing is started, the ion gun 9 is controlled based on the measured frequency difference, the programmed frequency difference, and the processing rate set value. Then, the ion gun 9 is gradually moved backward while irradiating ions to adjust the frequency, and the processing rate is controlled so as to gradually change from a fast state to a slow state. During this time, the electric power supplied to the ion gun 9 is kept constant, and stable irradiation capability can be secured. Therefore, the calculation and adjustment of the processing rate are simple, and the frequency can be adjusted with high accuracy. Further, it is possible to eliminate the trouble that the irradiation is interrupted, or the irradiation becomes excessive and the frequency becomes equal to or higher than the frequency f0 and the adjustment cannot be performed. When the monitored resonance frequency f0 of the work 3 reaches the target frequency of each block, the plasma is shut off and the work 3 is moved to the next block by the transfer mechanism 18.

The start and cutoff of irradiation of argon ions may be controlled by directly turning the DC power supply 13 on and off. Alternatively, the shutter 16 may be controlled by the shutter drive mechanism 17 to open and close while plasma is continuously generated. In order to perform stable irradiation with the ion gun, it is desirable to operate the ion gun in a steady state, and in that respect, it is effective to use the shutter 16 to turn it on and off. When the shutter 16 is turned off, the distance between the ion gun 9 and the work 3 is sufficiently secured in the processing apparatus of this example, and the processing rate is lowered. Therefore, a very high value is not required for the shutter speed and the responsiveness to control, and a known mechanism with established reliability can be used. In the apparatus of this example, the processing speed at the time of final matching is further reduced by using three blocks.
In this respect as well, no excessive demands are made on the shutter and its control mechanism.

FIG. 8 shows the state of frequency change of the piezoelectric element in the process of frequency adjustment using the apparatus of this example.
When irradiation is started at time t1, argon ions are irradiated to the electrode from the ejection port 5 located in the vicinity of the work 3, and the frequency sharply rises. Then, following the above process,
The distance between the ejection port 5 and the work 3 is gradually widened, the frequency change amount of the work is suppressed, and the fitting frequency gradually approaches. Then, by moving the ion gun 9 further away from the work 3 when it comes close to the matching frequency for each block, a processing rate suitable for adjustment is obtained. When the frequency f1 substantially matches the adjusted frequency f0 and the like at time t2, the irradiation is stopped. The timing of stopping the irradiation may of course have a certain range with respect to the target frequency in the upstream processing step.

FIG. 9 shows a schematic flow chart of the manufacturing process of the piezoelectric element using the apparatus of this example. First, in step 51, a metal electrode is formed on the surface of the piezoelectric element by vapor deposition or the like. Next, in step 52, the piezoelectric element (work) having electrodes is set in the processing apparatus of this example. And
In step 53, the first block is entered, and irradiation for rough adjustment is performed. The frequency f1 of the workpiece in this process is monitored in step 54, and irradiation is continued until the target frequency f0 ″ of the first block is reached. At this time, the distance between the work and the ion gun is adjusted based on the frequency monitored in step 55 so that an appropriate processing rate can be obtained.

Frequency f1 monitored in step 54
Reaches the target frequency f0 ″, the work 3 moves to the next second block by the transport mechanism, and irradiation for coarse / fine adjustment is performed in step 56. Also in this block, the frequency f1 is monitored in step 57,
It is compared with the target frequency f0 '. Irradiation is continued while adjusting the processing rate in step 58 until the target frequency f0 ′ is reached.

When it is determined in step 57 that the target frequency f0 'has been reached, the work 3 is further moved to the third position.
And the fine adjustment irradiation is performed in step 60. The frequency f1 is monitored in step 61,
Irradiation is continued while adjusting the processing rate in step 62 until it matches the matching frequency f0.
When the matching frequency and the monitored frequency match, the processing device is unloaded. Then, the piezoelectric element whose resonance frequency is accurately adjusted is supplied to a downstream step of processing the element into a commercially available state such as a surface mount device.

By adopting such a processing step, it is possible to adjust the individual work while monitoring the resonance frequency corresponding to the unique condition of the work. Therefore, the frequency of the work obtained by these steps, that is, the frequency of the piezoelectric element is very high, and the variation of the resonance frequency of the obtained piezoelectric element is also very small. Furthermore, there is almost no risk of frequency matching failure, and efficient manufacturing is possible without waste. As described above, by adopting the manufacturing method and the processing apparatus according to the present invention, the frequency adjusting method using plasma is actually applied to manufacture and provide a high-performance piezoelectric element at low cost in a short time. it can.

FIG. 10 shows an example of a piezoelectric element whose frequency is adjusted by the processing apparatus of this example. In the illustrated piezoelectric element 3, a rectangular AT-cut crystal piece is used as the piezoelectric body 3a, and silver is vapor-deposited on both surfaces thereof to form two electrodes 4a and 4b. And one of the electrodes 4
The thickness of b is irradiated with argon ions to reduce the thickness from the one indicated by the alternate long and short dash line 4c. The processing rate at the time of thickness reduction changes depending on the energy when the irradiated ions collide with the electrode. Therefore, in each of the three-stage blocks like the above-described processing apparatus, the distance between the work and the ion gun is set in advance to a distance at which energy suitable for performing the coarse adjustment, the coarse fine adjustment, and the fine adjustment is obtained. It is desirable to perform fine tuning by moving the distance back and forth. Alternatively, it is possible to use one ion gun for rough adjustment, coarse adjustment, and fine adjustment. In this case, if two drive mechanisms, which roughly adjust the distances of energy suitable for each process and a drive mechanism which finely adjusts the distances before and after those distances, are used, the frequency can be adjusted in the same process as above. Adjustments can be made. The adjustment of the distance is not limited to the ion gun side as in this example, but the work side may be moved, or both may be moved.

Similarly to the distance between the work and the ion gun, the ion current flowing from the ion gun to the work, the floating potential applied to the ion gun, or both can be adjusted to adjust the energy of collision with the work. is there. In addition to this, it is possible to change the type of gas to be ionized or change the distance equivalently by using a magnetic field or the like. Further, various means can be used to adjust the ability to reduce the thickness of the electrode, such as changing the area of the mask to control the irradiation amount to the electrode, and any of these means can be used. Of course, the present invention can be configured.

Furthermore, in the above-described processing apparatus, only one of the two electrodes 4a and 4b is reduced in thickness. Alternatively, of course, opposing electrodes may be provided to reduce the thickness of both electrodes. Further, the work is not limited to the AT-cut quartz crystal vibrating piece as shown in the figure, but a tuning fork type vibrating piece, an element using ceramic as a piezoelectric body, or the like, which can adjust the frequency by adjusting the electrode thickness. Of course, the present invention can be applied.

Further, in the above-mentioned processing apparatus, a plurality of works are conveyed in sequence to the three blocks arranged in parallel. However, these blocks are arranged radially and the works are provided for each block. Of course, the steps of coarse adjustment, coarse adjustment, and fine adjustment may be performed by turning. As described above, the arrangement of the plurality of blocks for frequency adjustment can be variously arranged in consideration of the layout of the manufacturing process and the characteristics of the manufactured element. Further, in the above-mentioned processing apparatus, the frequency is adjusted in three stages of coarse adjustment, coarse fine adjustment, and fine adjustment. These divisions are also possible from one stage to multiple stages of 4 stages or more, the ability of the ion gun and the work It can be set freely considering the characteristics. Also, similar effects can be obtained by performing irradiation with the work as one electrode for forming plasma, as in sputter etching.

FIG. 11 shows an aging characteristic at 85 ° C. of an AT-cut crystal unit having a fundamental wave of 26 MHz whose frequency was adjusted by the processing method using plasma of this example (FIG. 11).
(A)) and the aging characteristics of the same type of AT-cut crystal unit whose frequency is adjusted by conventional vapor deposition (Fig. 11).
(B)) is shown. As can be seen from the figure, in the vibrator whose frequency is adjusted by vapor deposition, a frequency change appears in about 100 hours, and a frequency fluctuation of 2 ppm or more is observed after 1000 hours. On the other hand, in the AT-cut crystal unit whose frequency is adjusted by using the plasma according to the present invention, no frequency change is observed in about 100 hours,
Even after 1000 hours, the frequency change of about 1/3 of the vibrator due to vapor deposition is only seen. Also,
FIG. 11 shows the frequency variation (3σ) after a predetermined time has elapsed. As can be seen from the figure, the AT-cut crystal unit whose frequency is adjusted by the processing method of the present invention has one
The variation in frequency after 000 hours is also small. As described above, the vibrator according to the present invention in which the frequency is adjusted by reducing the thickness of the electrode has extremely stable performance as compared with the conventional vibrator in which the frequency is adjusted by further depositing metal on the electrode. Therefore, a vibrator with high durability can be obtained.

As described above, the piezoelectric element whose frequency is adjusted by using the plasma, which is easily mass-produced by the manufacturing method and the processing apparatus according to the present invention, has a high resonance frequency accuracy,
It was found that the variation in resonance frequency was small and the aging characteristics were also very good.

FIG. 12 shows an outline of a crystal resonator in which a crystal vibrating body whose frequency is adjusted using crystal is sealed.
And FIG. 14 shows a cross section of the crystal unit.
The crystal unit 70 of the present example includes a cylindrical case 79 having a diameter of 2.0 ± 0.2 mm and a length of 6.0 ± 0.5 mm. The crystal resonator 3 is sealed inside the case 79, and the leads 72 are connected to the respective electrodes 4. The lead 72 is the base 71
Is led to the outside of the case 79 via the lead 72
The crystal vibrating body 3 can be supplied with electric power to oscillate.

FIG. 15 shows a crystal resonator 80 in which the crystal resonator 70 of the present example is molded with resin and surface-mounted. In this crystal oscillator 80, a lead 72 protruding from a cylindrical case 79 of the crystal oscillator 70 is welded to a metal lead 81 and molded with a resin 82. Since the case 79 is molded with the resin 82, the crystal unit 80 of this example is an element that can be mounted on the surface of the substrate as it is.

FIG. 16 shows a crystal oscillator 90 in which the crystal resonator 70 of this example and an IC integrated circuit 91 are combined and molded with resin. In this crystal oscillator 90, an IC integrated circuit 9 including at least a crystal resonator 70 and an oscillation circuit for oscillating the crystal resonator 70.
1 is mounted on a metal frame 92 in a state of being molded with resin 82. Then, by mounting the device 90 on the substrate, it is possible to supply a reference frequency that defines the operation of each circuit mounted on the substrate. Since the diameter of the crystal resonator 10 of this example can be made small, about 2 to 3 mm, the thickness of the oscillator can also be set to about 2.5 to 3.7 mm, and the size and weight can be made extremely small. Furthermore, by using the crystal oscillator of the present example, it is possible to stably supply a high-precision high frequency wave, so that the oscillator is suitable for an electronic device operating at high speed.

As described above, by adjusting the frequency of a piezoelectric element such as a crystal oscillator by using the manufacturing method and processing apparatus of the present invention, it can be used as an SMD (surface mount device) like an IC. Downsized,
It is possible to provide a vibrator and an oscillator that are light in weight and can stably oscillate a high-precision high frequency wave. Furthermore, since a piezoelectric element having such excellent characteristics can be provided at a high yield, the present invention will reduce the weight and size of the device, and further increase the speed of communication devices, information processing devices, and various electronic device fields. It is possible to provide a piezoelectric element suitable for the above, a vibrator using the same, and an oscillator.

[0052]

As described above, by using the manufacturing method and the processing apparatus according to the present invention, it is possible to realize a highly accurate piezoelectric element by actually using the frequency adjusting method using plasma which has been conventionally proposed. It is possible to efficiently manufacture and provide it. Therefore, in the present invention, the resonance frequency during frequency adjustment can be monitored, and the processing rate can be freely set while the irradiation source is stable. Therefore, it is possible to flexibly deal with the unique state of each piezoelectric element, and it is possible to provide a piezoelectric element with a small variation in resonance frequency. The piezoelectric element manufactured according to the present invention has good aging characteristics, and very stable performance can be obtained.

Furthermore, since the frequency can be adjusted while monitoring the resonance frequency, it is possible to perform highly accurate adjustment without adding factors such as experience and cans. Furthermore, it is said that the frequency is excessively adjusted. There is no problem. Therefore, the manufacturing method and the processing apparatus according to the present invention are suitable for the manufacturing process of the piezoelectric element which is advanced in automation.
The piezoelectric element can be efficiently manufactured. Furthermore, frequency adjustment is performed in multiple stages, and these two requirements are met at the same time, namely speedup of frequency adjustment and fine tuning, so that the frequency adjustment method using plasma can be actually adopted. .

[Brief description of drawings]

FIG. 1 is a block diagram showing an outline of a processing apparatus for performing frequency adjustment according to the present invention.

FIG. 2 is a perspective view showing one schematic configuration of a block of the processing apparatus shown in FIG.

3 is a block diagram showing a configuration of a frequency measurement system of the processing apparatus shown in FIG.

FIG. 4 is a diagram showing a different circuit configuration of the fixture shown in FIG.

FIG. 5 is a diagram showing a different circuit configuration that constitutes the fixture shown in FIG.

FIG. 6 is a diagram showing a different circuit configuration of the fixture shown in FIG.

7 is a block diagram showing a different configuration of the measurement system shown in FIG.

FIG. 8 is a graph showing how the processing rate changes in the frequency adjusting step.

FIG. 9 is a flowchart showing a manufacturing process of the present invention.

10 is a front view (a) and a side view (b) showing a piezoelectric element whose frequency is adjusted by the processing apparatus shown in FIG.

FIG. 11 shows the aging characteristics of the piezoelectric element shown in FIG.
It is a figure shown in comparison with the conventional piezoelectric element.

12 is a perspective view showing an outline of a vibrator in which the piezoelectric element shown in FIG. 10 is sealed.

13 is a cross-sectional view showing the configuration of the vibrator shown in FIG. 12, showing a state of the piezoelectric element cut in front.

FIG. 14 is a cross-sectional view showing the configuration of the vibrator shown in FIG. 12, showing a state of the piezoelectric element cut along the side surface.

FIG. 15 is an SMD obtained by molding the vibrator shown in FIG.
It is a figure which partially cuts and shows the structure of the vibrator of a type.

16 is a cross-sectional view showing a configuration of an oscillator in which the resonator shown in FIG. 12 and an IC for oscillation are packaged.

[Explanation of symbols]

 1. ・ Network analyzer 2 ・ ・ Fixture 3 ・ ・ Piezoelectric element 4 ・ ・ Electrode film 5 ・ ・ Spout 8 ・ ・ Gas cylinder 9 ・ ・ Frequency adjustment source (ion gun) 10 ・ ・ Vacuum container 11 ・ ・ Mechanical booster pump 12・ ・ Rotary pump 13 ・ ・ DC power supply 14 ・ ・ Drive device 15 ・ ・ External operation device 16 ・ ・ Shutter 17 ・ ・ Shutter drive mechanism 20 ・ ・ Piezoelectric element transfer mechanism 19 ・ ・ Resistance 20 ・ ・ Resistance 21 ・ ・ Resistance 22 ··coil

Claims (21)

[Claims] 1. A means for irradiating at least a part of an electrode formed on at least a part of the surface of a piezoelectric element with ionized particles, a measuring means for measuring the frequency of the piezoelectric element, and A processing device for a piezoelectric element, comprising: connecting means for removing the low frequency component from the electrode and connecting the measuring means. 2. The processing device for a piezoelectric element according to claim 1, wherein the connecting means includes a coil, one of which is connected to the electrode side and the other of which is connected to a ground side. 3. The apparatus for processing a piezoelectric element according to claim 2, wherein the connecting means includes a capacitance inserted between the one side and the means capable of measuring the frequency. . 4. The processing device for a piezoelectric element according to claim 2, wherein the connecting means includes a resistor connected in series with one side of the coil. 5. A means for irradiating at least a part of an electrode formed on at least a part of a surface of a piezoelectric element with ionized particles, and a distance between the means for irradiating these ionized particles and the electrode. A device for processing a piezoelectric element, comprising: 6. A first irradiation means for irradiating at least a part of an electrode formed on at least a part of a surface of a piezoelectric element with ionized particles, and at least a part of the electrode for the first irradiation. Second irradiation means for irradiating ionized particles having a lower ability to reduce the thickness of the electrode than means, and means for applying the first and second irradiation means to at least part of the electrode in this order. A device for processing a piezoelectric element, comprising: 7. The processing device for a piezoelectric element according to claim 6, wherein the second irradiation unit is a unit that emits ionized particles having lower energy than the first irradiation unit. 8. The method according to claim 6, wherein the first irradiation means and the first control means capable of controlling the distance between the first irradiation means and the electrode facing the first irradiation means, the second irradiation means, and the second control means. A processing device for a piezoelectric element, comprising: a second irradiation means and a second control means capable of controlling a distance between the facing electrode and the electrode. 9. The piezoelectric device according to claim 8, further comprising: a measuring unit capable of measuring the frequency of the piezoelectric element; and a connecting unit for removing the low frequency component from the electrode and connecting the measuring unit. Device processing device. 10. The processing device for a piezoelectric element according to claim 9, wherein the first and second control means control the distance based on a measurement result of the measuring means. 11. A step of forming a metal electrode on at least a part of the surface of the piezoelectric element, and a step of irradiating at least a part of these electrodes with ionized particles to adjust the frequency. In the processing step, the frequency of the piezoelectric element is monitored while the low frequency component of the current flowing through the electrode of the piezoelectric element is removed, and the method for manufacturing the piezoelectric element. 12. A step of forming a metal electrode on at least a part of the surface of the piezoelectric element, and a step of irradiating at least a part of these electrodes with ionized particles to adjust the frequency. A method for manufacturing a piezoelectric element, wherein in the processing step, a distance between the particle irradiation source and the electrode facing the irradiation source is controlled. 13. A step of forming a metal electrode on at least a part of the surface of the piezoelectric element, and a step of irradiating at least a part of these electrodes with ionized particles to adjust the frequency. In the processing step, the frequency of the piezoelectric element is monitored while removing the low frequency component of the current flowing through the electrode of the piezoelectric element, and the irradiation source of the particles based on this frequency and the electrode facing the irradiation source, A method for manufacturing a piezoelectric element, comprising controlling the distance between the two. 14. A step of forming a metal electrode on at least a part of the surface of the piezoelectric element, and a first processing step of irradiating at least a part of the electrode with ionized particles to adjust the frequency. A second processing step of irradiating at least a part of the electrode with ionized particles having a lower ability to reduce the thickness of the electrode than in the first processing step and adjusting the frequency. Manufacturing method. 15. The method of manufacturing a piezoelectric element according to claim 14, wherein in the second processing step, ionized particles having a lower energy than in the first processing step are irradiated. 16. The method according to claim 14, wherein in the first processing step, the frequency of the piezoelectric element is monitored while removing the low frequency component of the current flowing through the electrode, and the frequency of the particles is monitored based on the monitored frequency. A method of manufacturing a piezoelectric element, comprising controlling a distance between an irradiation source and the electrode, and transitioning to the second processing step when the monitored frequency reaches a target frequency. 17. A piezoelectric body and an electrode formed on at least a part of a surface of the piezoelectric body, wherein at least a part of the electrode is reduced by ionized particles. Piezoelectric element. 18. The method according to claim 17, wherein at least a part of the electrode is continuously or stepwise reduced in thickness by the ionized particles having different ability to reduce the thickness of the electrode. And a piezoelectric element. 19. At least a part of at least one electrode formed on at least a part of the surface of the piezoelectric body is continuously or stepwise by ionized particles having different ability to reduce the thickness of these electrodes. A vibrator having a piezoelectric element reduced in thickness and a hollow housing that protects the piezoelectric element. 20. The vibrator according to claim 19, wherein the housing is molded by a molding member. 21. The vibrator according to claim 19, and an integrated circuit device including an oscillation circuit of the piezoelectric element, wherein the housing and the integrated circuit device are molded together by a molding member. Oscillator.