JP2003060461A - Method and apparatus for manufacturing piezoelectric vibration piece - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and apparatus for manufacturing a piezoelectric vibration piece, which is capable of suppressing variations in the thickness between recessed parts generated in initial etching within a prescribed range reliably and in a short time, without adding the step of sticking a porous thick plate on a wafer in the midway of a conventional manufacturing step or other steps. SOLUTION: The surfaces of crystal wafers 12 exposed from a mask are etched in batch, and frequencies of excitation portions 14 formed on each wafer 12 are measured independently. An etching start time is delayed for each portion 14, so that the end point of etching results in the same, on the basis of the etching times of the individual portions 14 which is calculated, so that the frequency of each portion 14 is within the prescribed range, and an etching liquid 18 is dropped on each portion 14, by using a pump 40 and a syringe 38.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for manufacturing a piezoelectric vibrating piece, and more particularly to a method and an apparatus for manufacturing a piezoelectric vibrating piece suitable for forming an inverted mesa type piezoelectric vibrating piece.

[0002]

2. Description of the Related Art It is known that an inverted mesa type resonator element shape is used in a high-frequency compatible piezoelectric resonator represented by a crystal resonator. When forming the inverted mesa-type vibrating piece, first, the surface of the wafer is polished by machining, and then the concave portions that form the plurality of excitation portions are formed on the plane of the wafer by etching. I have to.

However, when forming a concave portion,
The thickness of the excitation portion, which is the bottom of the recessed portion, is subtly different due to variations in plate thickness due to polishing of the wafer or variations in dry etching or wet etching. As for the polishing accuracy of the wafer, for example, in a 30 mm square wafer, the plate thickness is about 100 ± 0.5 μm, and the variation in the plate thickness as a wafer is about 1%. If the etching is performed so that the thickness is about 10 μm, even if there is no variation in the etching, the variation in the plate thickness in the recess is 10
It becomes ± 0.5 μm, and the variation in the thickness of the excitation portion between the concave portions reaches as much as 10%.

In order to correct this variation, Japanese Unexamined Patent Publication (Kokai) No. Hei 6
As disclosed in Japanese Patent Publication No. 21740, the thickness of a recess formed on the surface of a wafer is measured, and a thick plate of bakelite in which holes are formed at the position corresponding to the opening of the recess is bonded with an adhesive. There is known a method of adhering and supplying an etching solution to each recess so that the thickness of the recess falls within a preset range.

[0005]

However, in the above-mentioned method, since it is necessary to bond the porous thick plate to the surface of the wafer with an adhesive, a separate bonding step is required. Furthermore, the thickness of the wafer is extremely thin, approximately 80 μm to 100 μm, and there are local recesses with a depth of 60 μm to 70 μm everywhere. Therefore, the wafer is damaged during bonding of the thick plates or peeling of the thick plates. There is a risk.

Further, since the etching liquid is supplied through the thick plate, a large amount of etching liquid is required, and even if the etching liquid is supplied, the bubbles in the concave portion do not escape, and the etching liquid is the bottom of the concave portion. It may not reach the (excitation part) (may not be etched).

The present invention focuses on the above-mentioned conventional problems and, without adding a step of attaching to a wafer or the like during the conventional manufacturing process, further varies the thickness of each concave portion caused by the first etching. It is an object of the present invention to provide a method and an apparatus for manufacturing a piezoelectric vibrating reed, which can surely and quickly hold the piezoelectric vibrating piece within a preset range.

[0008]

According to the present invention, if a mask made of a resist film formed on the surface of a wafer is used instead of a thick plate during the manufacturing process of a piezoelectric vibrating piece, the conventional manufacturing process is not performed. This is based on the finding that the variation in the thickness of each recess can be kept within a preset range without making a large change.

That is, in the first piezoelectric vibrating reed manufacturing method according to the present invention, after the mask made of the resist film is formed on the surface of the wafer, the surface of the wafer exposed from the opening of the mask is etched to excite the exciting portion. A method of manufacturing a piezoelectric vibrating piece, wherein the etching is divided into a first etching step and a second etching step, and the surface of the wafer exposed from the mask is collectively etched in the first etching step. After forming a plurality of excitation portions, the frequency of each excitation portion is measured, and the etching end point is calculated based on the etching time of each excitation portion calculated so that the frequencies of these excitation portions fall within the set range. So that the etching start time of each excitation section is shifted so that
The etching process is performed for each excitation unit.

According to the first aspect of the present invention as described above, the wafer on which the mask is formed in the first etching step is dipped in an etching solution, and a portion of the wafer exposed from the mask is etched to form a depression (concave portion). By providing, a plurality of excitation parts are collectively formed. Then, in the second etching step, a mask made of a resist film is used instead of the conventional thick plate. That is, since the mask formed of the resist film which is an organic material has a large liquid repellency, when the etching liquid is supplied to each excitation part, the etching liquid is easily retained in the recess due to the liquid repellency of the mask. The second etching step can be performed. Therefore, it is not necessary to add a process such as attaching a thick plate to the wafer during the conventional manufacturing process, and the variation of the thickness of the excitation part formed by the first etching process, which is the first etching, can be reliably and shortened. In time, it can fit within a preset range.

In this case, if the supply amount of the etching solution used in the second etching step is set so as not to protrude from the opening of the resist film, that is, at the maximum, up to the state where the resist film is raised by the surface tension, the excitation is performed. It is possible to secure a sufficient amount of the etching liquid for adjusting the thickness of the portion, and the amount of the etching liquid used becomes minute so that the amount of the etching liquid used can be reduced.

Further, in the second method for manufacturing a piezoelectric vibrating piece according to the present invention, after a mask made of a resist film is formed on the surface of the wafer, the surface of the wafer exposed from the opening of the mask is etched to make a plurality of excitations. First to collectively form parts
An etching step, a mask removing step of removing a mask from the surface of the wafer, and before or after this mask removing step, to measure the frequency of each of the excitation parts and to keep the frequency of each excitation part within a set range. Based on the etching time of each of the excitation parts obtained in the time calculation step for obtaining the etching time of, the etching start time of each excitation part is shifted so that the etching end points coincide with each other. And a second etching step of etching.

According to the second aspect of the present invention, since the mask made of the resist film is removed before the second etching step, the gas generated from the mask does not adhere to the excitation part.
Therefore, the etching solution supplied to the exciting section easily wets the exciting section without being hindered by the gas adhering to the exciting section, and the time from the supply of the etching solution in each exciting section to the start of etching Being constant,
The film thickness of the excitation part can be adjusted with high accuracy.

According to the research conducted by the inventors of the present application, although the reason is not clear, the smaller the amount of the etching solution supplied to the exciting portion in the second etching step is, the more stable the etching can be performed, and the thickness of the exciting portion can be adjusted. Can be performed with higher accuracy. Therefore, the supply amount of the etching liquid to the exciting portion in the second etching step is at least an amount that can wet and cover the entire exciting portion, and it is desirable that the amount be as small as possible. The following is recommended.

When etching a wafer, a corrosion resistant film made of a conductive metal such as Au / Cr is usually formed on the surface of the wafer. Therefore, when measuring the frequency of the excitation unit, the conductive corrosion resistant film may be grounded. If the anticorrosion film is grounded at the time of measuring the frequency of the excitation part, the anticorrosion film around the excitation part becomes the ground potential, and the frequency can be surely measured without being affected by external noise when measuring the frequency.

It is desirable that the second etching step be performed after cleaning the excitation part. By cleaning the excitation part and removing the organic substances adhering to the excitation part,
Since the wettability of the excitation part is improved and the etching liquid easily wets the excitation part, etching is started at the same time as the supply of the etching liquid, the etching variation is reduced, and the film thickness can be adjusted with higher accuracy. Further, when a surfactant is added to the etching liquid, the adsorbability of the etching liquid is improved, the exciting portion is easily wetted, the variation in etching is reduced, and the film thickness can be adjusted with high accuracy.

The second etching step can be performed using a plurality of etching solutions having different concentrations. Since the second etching process is performed by supplying the etching solution to each exciting part, the etching time can be shortened by supplying the etching solution having a high concentration to the exciting part having a long etching time.

When the etching solution is supplied to the exciting part in the second etching step, after inserting the tip of the supply pipe into the recess forming the exciting part, a droplet of the etching solution is grown on the end of the supply pipe. The droplet may be brought into contact with the excitation unit. When the etching solution is supplied to the exciting section in this manner, the etching solution can be prevented from splashing to other parts, and the etching solution spreads to the exciting section that is the bottom of the depression, and then the etching solution flows upwards from the depression. Since the surface moves, the gas inside the depression can be discharged,
It is possible to prevent bubbles from being generated in the excitation section, and to easily and surely wet the excitation section with the etching solution. Further, by positioning the tip of the supply pipe at the center of the excitation part, it is possible to make the etching liquid spread evenly on the excitation part and prevent defective etching due to generation of bubbles or the like.

The apparatus for manufacturing a piezoelectric vibrating piece according to the present invention for carrying out the above manufacturing method includes a frequency measuring means for measuring the frequency of an exciting portion formed on the surface of a wafer, and a value from the frequency measuring means. The control calculation unit that calculates the etching time of each excitation unit based on the above, and the etching liquid is dropped onto each excitation unit by shifting the time so that the etching end points match based on the value from this control calculation unit. And an etching liquid supply means for performing the etching. Accordingly, the second etching step in the method for manufacturing a piezoelectric vibrating piece described above can be performed easily and reliably.

A plurality of etching liquid supply means can be provided so that etching liquids having different concentrations can be dropped.
Thereby, the etching time in the second etching step can be shortened by supplying the exciter with the etching liquid having different concentrations depending on the length of the etching time in the second etching step. Further, it is desirable that the tip of the etching supply means be smaller than the excitation part so that it can be inserted into the recess forming the excitation part. By supplying the etching liquid to the excitation part by inserting the tip of the etching liquid supply means into the recess, it is possible to prevent the etching liquid from splashing around, and to supply the etching liquid to the excitation part without generating bubbles. You can

The delivery of the etching liquid in the etching liquid supply means is provided with a deformable supply pipe for supplying the etching liquid and the supply pipe sandwiched therebetween, and the supply pipe is deformed at arbitrary intervals. And a rotating body forming When the rotating body having eccentricity or unevenness is rotated, the rotating body partitions the inside of the supply pipe at a constant interval and can deliver a constant amount of the etching solution, so that the etching solution can be supplied with high accuracy. The delivery of the etching solution in the etching solution supply means may be constituted by an actuator using a piezoelectric element. Also in this case, the supply amount of the etching liquid to the excitation unit can be controlled with high accuracy.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Specific preferred embodiments of the method and apparatus for manufacturing a piezoelectric vibrating piece according to the present invention will be described in detail below with reference to the drawings. FIG. 1 is an explanatory view showing the structure of the piezoelectric vibrating piece manufacturing apparatus according to the first embodiment.
As shown in the figure, a crystal vibrating piece manufacturing apparatus 10 (hereinafter, referred to as a manufacturing apparatus 10) that is a piezoelectric vibrating piece according to the present embodiment is provided in the middle of a crystal vibrating piece manufacturing process.

The manufacturing apparatus 10 includes a frequency measuring unit 16 serving as a frequency measuring unit for measuring the frequency of the excitation unit 14 formed on the surface of the crystal wafer 12, and the frequency measuring unit 1.
Based on the value of 6, the etching solution 18
And a liquid supply unit 20 serving as an etching liquid supply unit for supplying the. The frequency measuring unit 16
And a liquid supply unit 20 are provided with a conveyor device (not shown), and the crystal wafer 12 is provided in a direction indicated by an arrow 22.
Can be transported.

The frequency measuring unit 16 is provided with a stage 24 for mounting the crystal wafer 12, and above the stage 24, the frequencies of the plurality of excitation units 14 formed on the crystal wafer 12 are measured. A network analyzer 26 and a probe 28 for the network analyzer 26 are provided. The probe 28 is attached to a robot arm 30 so as to be freely movable within the range of the stage 24, and the tip of the probe 28 can be brought close to the excitation unit 14 by an elevator device (not shown). It is possible to measure the frequency of the excitation unit 14 of.

A cylinder device 32 is provided on the end side of the stage 24, and the cylinder device 32 is provided.
Is operated, the tip of the cylinder rod is brought into contact with the corrosion resistant film 34 formed on the surface of the crystal wafer 12, and the corrosion resistant film 34 is grounded to the ground potential. The resist film 62 is peeled off from the portion of the corrosion resistant film 34 that contacts the cylinder rod. As a result, the potential of the anticorrosion film 34 around the excitation unit 14 becomes constant, and the anticorrosion film 34 serves as a shield during the frequency measurement using the network analyzer 26, and prevents external noise from entering the probe 28. You can do it. In this step, the above-mentioned corrosion-resistant film 34 need only have electrical conductivity, and normally, a thin film of Cr having a thickness of 10 to 100 nm in the lower layer and Au of 50 to 300 nm in the upper layer is deposited or sputtered. The two-layer structure formed in step 1 is common.

Further, the crystal wafer 1 is mounted on the robot arm 30.
The coordinates of the excitation unit 14 formed on the surface of No. 2 are stored in advance, and the probe 28 is moved in association with the measurement of the network analyzer 26 so that the individual excitation units 14 can be continuously measured.

The liquid supply unit 20 for supplying the etching liquid 18 to the excitation unit 14 is also provided with a stage 36, like the frequency measurement unit 16, and the stage 36 is provided.
A syringe 38 that constitutes a dispenser is provided above. The syringe 38 uses the etching solution 18
Is connected to a pump main body 40 for supplying the etching liquid, and the etching liquid 18 can be discharged from the tip of the nozzle of the syringe 38 by receiving a signal from a control calculation unit described later. The syringe 38 is also attached to the robot arm 42, like the probe 28 in the frequency measurement unit 16, and the operation of the robot arm 42 allows the syringe 38 to move within the stage 36.

By the way, the transfer device 4 having the network analyzer 26 in the frequency measuring unit 16 and the pump body 40 and the robot arm 42 in the liquid supply unit 20.
4, a control arithmetic unit 46 is provided, and the control arithmetic unit 46 controls the pump main body 40 and the transfer device 44 based on the output signal of the network analyzer 26.

FIG. 2 is a flow chart showing the processing procedure of the control calculation section and the state of the table calculation (processing item and processing result) at each step. As shown in the figure, in the control calculation unit 46, when the frequency is input from the network analyzer 26 (step 100),
Excitation part (concave part) 1 formed on the surface of the crystal wafer 12
4 (14A, 14B, 14C, ...) Is linked to the positions of 4 (14A, 14B, 14C, ...) And the frequency is recorded in the memory to create a data file (step 110). When all the frequencies of the excitation unit 14 formed on the surface of the quartz wafer 12 are captured in this way, the data file is read (step 120) and these values are converted from the frequency to the plate thickness in the excitation unit 14 ( Step 130). The excitation unit 14
In order to convert the frequency at 1 to the plate thickness, the calculation may be performed using the following formula.

[Equation 1] However, the coefficient 1670 on the right side of Expression 1 is a frequency constant (unit: kHz · mm), and the unit of the plate thickness of the excitation part is m.
The unit of m and frequency is kHz.

After the plate thickness of the excitation part 14 is calculated by the above equation, a preset target plate thickness is input, and the difference between the plate thicknesses of the individual excitation parts 14 is made, that is, etching is performed. The power amount is calculated (step 140). The target plate thickness may be stored in the control calculation unit 46 in advance.

Next, after calculating the difference with respect to the target plate thickness, the etching rate by the etching solution 18 is input,
The time required for etching the difference is calculated (step 150). Note that the etching rate may be stored in the control calculation unit 46 in advance, like the target plate thickness.

After the etching time in each of the exciting parts 14 is calculated in this way, the difference in the etching time between the individual exciting parts 14 is calculated so that the end points of the etching are the same, and at the same time, in the exciting part 14. The order of dripping the etching liquid 18 and the dripping start time are set (step 1
60).

FIG. 3 is an explanatory view showing a method of setting the order of dropping the etching liquid and the dropping time in each of the exciting portions. As shown in FIG. 1A, a plurality of excitation parts 14 (only 14A to 14E are numbered) are provided on the surface of the crystal wafer 12.
Are formed. And these excitation parts 14A-14E
When the frequencies a0 to e0 are measured, the etching time until the target plate thickness is reached is calculated from the above values, as described above. Here, as shown in FIG. 2B, the dropping order of the etching liquid 18 is set in each of the excitation units 14 so that the etching end points coincide with each other.

For example, the calculated etching times of the exciters 14A to 14E are ta, tb, tc, td, respectively.
When te is such that ta>tc>te>td> tb, the etching time ta of the excitation unit 14A having the longest etching time is used as a reference, and the start time of the dropping of the etching solution to the excitation unit 14A (etching start time ) Is set to 0. Then, for the other excitation units 14B to 14E, (ta-
tb), (ta-tc), (ta-td), (ta-t
The etching solution 18 may be dropped onto each of the excitation units 14A to 14E with the time difference of e). That is, the excitation unit 14
After starting to add the etching solution to A (ta-tc)
At the time when a second has elapsed, the dropping of the etching liquid onto the excitation unit 14C is started, and at the time when (ta-te) seconds have elapsed from the start of the dropping of the etching liquid onto the excitation unit 14A, the etching liquid is dropped onto the excitation unit 14E. Set to start. Hereinafter, similarly, the dropping start time of the etching liquid is set in the order of longer etching time. As a result, the etching end point (end time) of each excitation unit 14 can be aligned with ta.

Then, as shown in FIG.
After setting the order of dripping the etching solution 18 and the dripping start time, the control calculation unit 46 transmits the table data to the transfer device 44 and the pump body 40 (step 17).
0). When the transfer device 44 receives the value from the control calculation unit 46, the robot arm 42 is moved to a specific position of the excitation unit 14 (step 180), and the nozzle tip of the syringe 38 is moved to the recessed portion forming the excitation unit 14 ( Then, the etching liquid 18 is supplied to the excitation unit 14 by operating the pump body 40 (step 190).

After the end of the etching time (step 200), cleaning water is added to the surface of the crystal wafer 12 and the etching liquid 1 supplied to the excitation unit 14 by water cleaning is added.
8 is removed and the etching process is completed (Step 2
10).

FIG. 4 is an explanatory diagram showing the measurement principle of the network analyzer, (1) of FIG. 4 is a peak value detection waveform in the excitation section, and (2) of FIG. 4 is a measurement circuit diagram using the network analyzer. Indicates.

Zx shown in (2) of the figure is an exciting section to be measured, and the reference signal source V is applied to the exciting section Zx.
The signal is applied to the excitation unit while sweeping from s to an arbitrary frequency range (for example, 155 ± 1 MHz when the reference frequency is 155 MHz). Then, the reference signal Vr is directly transmitted from the transmission section in the network analyzer to the reception section together with the application to the excitation section.

The receiving unit receiving the reference signal Vr from the transmitting unit compares the output signal Vx from the exciting unit with the reference signal Vr, and calculates the impedance from the voltage drop due to the exciting unit. Then, this impedance becomes smaller near the resonance frequency and becomes larger near the anti-resonance frequency thereafter, as shown in FIG. Then, the main frequency of the excitation unit to be measured can be measured by peak-holding the value of the resonance frequency. In the network analyzer, unlike the spectrum analyzer, the output signal Vx from the excitation unit is converted into the reference signal Vx.
It goes without saying that the phase can also be measured because it is compared with r. As shown in (1) of the same figure, the peak detected at a higher level than the main vibration of the excitation section is spurious vibration, which is mainly caused by mechanical resonance of the excitation section.

FIG. 5 is an enlarged view of essential parts showing the structure of the pump body according to the present embodiment, and FIG. 6 is an enlarged sectional view showing the structure of the pump body replacing FIG. As shown in FIG. 5, the pump body 40 mainly includes a tube retainer 40A, a tube 40B, and a tube guide 40C. The tube retainer 40A is rotatable as shown by an arrow 40D, and a plurality of cam convex portions 40E are provided on the peripheral portion at equal intervals with respect to the center. The surface of the tube guide 40C that faces the circumferential surface of the tube retainer 40A is an arc-shaped guide surface 40F that follows the rotation locus of the tip of the cam protrusion 40E. Also, the tube 40B
Is arranged between the tube retainer 40A and the tube guide 40C. The tube 40B is for transporting the etching liquid, and is formed of a flexible member that is deformable.

This pump body 40 is a tube retainer 40.
When A rotates as indicated by arrow 40D, the cam convex portion 40E moves the tube 40B to the guide surface 40 of the tube guide 40C.
By pressing F, a minute space 40G of the tube 40B filled with the etching liquid is formed between the adjacent cam protrusions 40E. Then, as the tube retainer 40A rotates, the minute space 40G moves leftward in FIG.
A fixed amount of the etching solution that satisfies G is sent out from the pump main body 40 and is discharged from the syringe 38 as shown by an arrow 40H. As a result, it is possible to send out a very small amount of an accurate etching liquid to the syringe 38.

As described above, since it is possible to feed a small amount of the etching liquid by the pump main body 40, the syringe 38 is inserted into the exciting portion (concave portion) 14 of the crystal wafer 12 on the surface of which the mask made of the resist film is formed. When the etching liquid 18 is discharged to supply the etching liquid, the excitation unit 1
It can be supplied so that it does not overflow from 4.

Further, as shown in FIG. 6, the pump body 40 may be composed of a piezoelectric element 56 represented by a piezo element or the like. When the piezoelectric element 56 is used, the control calculation section 46 may be connected to the piezoelectric element 56 and the ejection pulse signal may be sent from the control calculation section 46. When the pulse signal is sent from the control calculation unit 46 in this manner, electrostriction occurs in the piezoelectric element 56 and the thin plate portion 58 is deformed as shown by the broken line in the figure. When the dimension D in the figure is changed by the deformation of the thin plate portion 58, the sealing member 57b of the check valve on the inflow side moves to the position 57c shown by the broken line, and the check valve on the inflow side and the check valve on the outflow side are moved. A backflow of the etching solution 18 between the check valve and the check valve is prevented, and a check valve (57a) on the outflow side is provided.
Since the etching liquid 18 passes through, the etching liquid 18 can be transported in the direction indicated by the arrow 60, and the etching liquid can be sent to the syringe 38 side.

FIG. 7 is an explanatory view showing the state of the etching liquid discharged from the dispenser. As shown in FIG. 1A, the robot arm 42 is attached to an arbitrary excitation unit 14.
(See FIG. 1) and after aligning the syringe 38 with the excitation unit 14, the nozzle tip of the syringe 38 is lowered to a position below the surface of the crystal wafer 12 to move the excitation unit 14 Insert into the recess that is being formed. For the purpose of supplying the etching liquid 18 without generating bubbles, the syringe 3 is attached to the center of the excitation unit 14.
It is desirable to match the centers of eight.

After the syringe 38 is aligned with the excitation unit 14 in this way, the pump body 40 is operated to discharge the etching liquid 18 from the tip of the nozzle of the syringe 38. When the etching liquid 18 that grows at the tip of the nozzle of the syringe 38 comes into contact with the excitation unit 14, the etching liquid 18 spreads from the syringe 38 to the entire excitation unit 14. This state is shown in FIG. Then, as shown in FIG. 3C, when the etching liquid 18 is continuously supplied from the syringe 38, the etching liquid 18 raises the liquid level while expelling the gas in the depression (recessed portion) and above the excitation portion 14. A liquid pool is formed by the etching liquid 18 on the
Etching can be advanced.

The edge of the opening connected to the excitation unit 14 is
Since the mask made of the resist film is formed in advance, after the syringe 38 is pulled up, the etching liquid 18 is repelled by the liquid repellency of the mask, and as shown in FIG. Thus, it is possible to hold the etching solution 18 in a hemispherical shape and prevent the etching solution 18 from flowing into the adjacent excitation section 14.

A procedure for manufacturing a crystal vibrating piece using the manufacturing apparatus 10 thus configured will be described. 8 and 9
FIG. 4A is an explanatory view of a process showing a manufacturing process of a quartz crystal resonator element. As a corrosion-resistant film 34 of hydrofluoric acid on both surfaces of the crystal wafer 12 as shown in FIG. 8A, Cr is 50 nm and Au is 10 nm.
The film is formed by vapor deposition or sputtering at 0 nm. This state is shown in FIG.

Then, as shown in FIG. 3C, Au / Cr
A photoresist is applied on the corrosion resistant film 34 and dried to form a resist film 62. Next, as shown in FIG. 4D, a photomask 6 on which a pattern of an inverted mesa portion is drawn
The surface of the wafer 4 is exposed to ultraviolet light, and the pattern of the photomask 64 is transferred to the resist film 62. Then, the exposed resist film 62 is developed with a developing solution to form a mask, and the Au / Cr anticorrosion film 34 in a portion corresponding to the excitation portion 14 is exposed as shown in FIG.

After exposing the corrosion resistant film 34 in this manner,
As shown in FIG. 9A, the corrosion resistant film 34 exposed from the resist film 62 is removed by etching to expose the surface of the crystal wafer 12. Next, as shown in FIG. 2B, the quartz wafer 12 is half-etched with a hydrofluoric acid-based etching solution, which is the first etching step, to form a recess (recess) in the quartz wafer 12 to form a plurality of excitation portions 14. Are collectively formed.

After forming the excitation portion 14 in the above process, the manufacturing apparatus 10 is used to perform the process shown in FIG.
The frequency in each excitation unit 14 is measured and converted into a plate thickness. Then, the time until the etching is completed is calculated from the difference between the plate thickness calculated from the target frequency and the etching rate, and the excitation unit 14 is etched in the second etching step for the calculated time. Then, after the etching of the individual excitation parts 14 is completed, the resist film 62 remaining on the surface of the crystal wafer 12 is peeled off as shown in FIG. 9C, and Au / Cr
The corrosion-resistant film 34 made of may be peeled off. As described above, by using the manufacturing apparatus 10 described above, it becomes possible to easily perform fine adjustment of the thickness of the excitation unit 14 without largely changing the conventional manufacturing process.

FIG. 10 is a diagram showing the result of adjusting the thickness of the exciting portion 14 as described above. FIG. 1A shows each excitation unit 14 when the first etching process is completed.
Is measured by a network analyzer, and the measured frequency deviates from the reference frequency corresponding to the target thickness (in this case, 175.5 MHz). Further, FIG. 2B shows that after the thickness of each excitation part 14 is individually adjusted by the second etching process,
Similarly, the frequency of each excitation unit 14 is measured and the amount of deviation from the reference frequency is obtained. In each case, the horizontal axis represents the number of the excitation units 14, and the vertical axis represents the frequency shift amount expressed in MHz.

In the sample used, the size of the depression (recessed portion) forming the excitation part 14 is 3.4 mm in length and 1.8 m in width.
m, depth 0.046 mm, the volume of the recess is 2.
It is 82 × 10 ⁻⁴ mL. The etching solution used in the second etching step was a mixed solution of hydrofluoric acid and an ammonium fluoride aqueous solution, and the amount of the etching solution supplied to the excitation part 14 was 3.26 × 10 ⁻⁴ mL. So that it rises from the recess. Further, the second etching step was performed at room temperature.

Comparing (1) and (2) in FIG. 10,
By performing the second etching process, the amount of frequency shift can be reduced. That is, the standard deviation of the amount of deviation from the reference frequency of the excitation unit 14 at the end of the first etching step shown in FIG. 1A was σ = 1.837, but the second etching of FIG. After the process, the standard deviation of the amount of deviation from the reference frequency was σ = 1.360.

By the way, the inventors of the present invention are
As a result of further research and study on the etching process, it was found that the variation in thickness can be further reduced by reducing the amount of the etching solution 18 supplied to the excitation unit 14. That is, it has been found that the supply amount of the etching liquid 18 to the excitation unit 14 is an amount that can wet the entire excitation unit 14 that is the bottom of the recess, and it is desirable that the supply amount be as small as possible. Specifically, it is desirable that the liquid level of the etching liquid 18 be set to be equal to or lower than the surface of the crystal wafer 12.

In this case, if a mask made of the resist film 62 (see FIG. 1) is present on the surface of the quartz wafer 12, it becomes difficult to wet the whole of the excitation part 14 with a small amount of the etching solution 18. The resist film (mask) is removed. It is considered that this is because the gas generated from the resist film 62 adheres to the excitation part 14 and repels the etching liquid. Further, if the gas generated from the resist film 62 adheres to the excitation part 14, it affects the wettability of the etching liquid 18, and therefore the time from the dropping of the etching liquid 18 of the excitation part 14 to the start of etching. It will be mixed,
It was found that the etching amount varies. Therefore, when the thickness of the excitation part 14 is adjusted more precisely, it is desirable to remove the resist film 62 from the surface of the crystal wafer 12 before performing the second etching step. Furthermore, it is advisable to clean the excitation part 14 immediately before the second etching step so that the entire excitation part 14 can be easily wet with a small amount of the etching solution 18 to remove the organic substances attached to the excitation part 14. The cleaning of the excitation unit 14 may be dry cleaning such as ultraviolet irradiation, oxygen plasma cleaning, or ion bombardment, or wet cleaning using a cleaning liquid such as sulfuric acid-hydrogen peroxide solution cleaning.

It is also possible to add a small amount of a surfactant to the etching solution to reduce the surface tension of the etching solution and enhance the adsorbability of the etching solution to improve the wettability. The amount of the surfactant added is preferably such that it does not affect the etching solution 18, and for example, several hundred ppm of a hydrocarbon-based surfactant is added. As a result, the etching liquid 1
When 8 is dropped on the excitation unit 14, the etching liquid 18 easily spreads. Moreover, the etching liquid 18
Since even the small recesses of the excitation part 14 enter, the surface of the excitation part 14 is uniformly etched, and the etching rate (etching rate) is stabilized. The surfactant is usually an anion type (anion type) alone or as a mixture of two or more, but an amphoteric surfactant or a nonionic surfactant is used as long as it has the same action. You may.

FIG. 11 is a flow chart showing the outline of the manufacturing process for explaining the method of manufacturing the piezoelectric vibrating piece according to the second embodiment. First, as shown in step 71 of FIG. 11, a corrosion resistant film made of Au / Cr or the like is formed on the surface of the crystal wafer 12 by vapor deposition or sputtering. next,
A photoresist is applied on the corrosion resistant film and dried to form a resist film. Further, the resist film is exposed and developed to remove the resist film in the part corresponding to the excitation part, and a mask made of the resist film exposing the corrosion resistant film in the part corresponding to the excitation part is formed (step 72).

After that, a first etching step is performed to etch the portion exposed from the mask (step 7).
3). This first etching step consists of etching the corrosion resistant film and etching the quartz wafer. In the first etching step, first, the corrosion resistant film exposed from the mask is etched (step 73A) to expose the quartz wafer in the portion corresponding to the excitation part. Next, the exposed quartz wafer is half-etched using an etching solution such as a mixed solution of hydrofluoric acid and ammonium fluoride to collectively form a plurality of excitation parts (step 73).
B). When the first etching step of step 73 is completed, a mask removing step of removing the mask on the surface of the quartz wafer is performed (step 74). After that, a time calculating step for obtaining the etching time of each exciting portion in the second etching step is performed (step 75). Note that step 75
The time calculation step may be performed before the mask removal step of step 74.

In the time calculating step, first, the frequency of each exciting section is measured (step 75A). This frequency measurement is performed using a network analyzer, as in the above embodiment. When measuring the frequency of each excitation part,
Similarly to the above, the corrosion resistant film provided on the surface of the crystal wafer is grounded to the ground potential. The frequency of each excitation unit measured by the network analyzer is input to the control calculation unit. The control calculation unit converts the input frequency into the film thickness of the excitation unit according to Formula 1 (step 75B). further,
The control calculation unit compares the input or stored target film thickness with the film thickness of each excitation unit obtained from the measurement frequency, and obtains the deviation between the two. Then, the control calculation unit calculates the etching time required to etch the thickness corresponding to the obtained deviation based on the etching rate of the crystal wafer by the input or stored etching solution (step 75C). ).

When the time calculation step is completed in this way, the control calculation section determines the order of dropping the etching liquid and the dropping time of the etching solution for each exciting section, as shown in step 76. The order of dropping the etching solution is determined in the order of longer etching time, that is, in the order of larger deviation from the target film thickness, as described above. In addition, the etching liquid dropping start time is based on the etching liquid dropping start time to the excitation unit having the longest etching time, and the etching end time of each excitation unit is the same as that shown in FIG. 3B. Determined to match.

Then, the excitation part is washed to remove the organic substances attached to the excitation part (step 77). The cleaning of the excitation unit may be dry cleaning such as ultraviolet irradiation, oxygen plasma cleaning, ion bombardment, or wet cleaning such as sulfuric acid-hydrogen peroxide solution cleaning. Further, it is desirable to clean the excitation part immediately before the second etching step shown in step 78. This is after cleaning the excitation part,
This is because if left for a long time, dust and the like floating in the air may adhere to the second etching step. Then, for example, when the mask removing step of step 74 is performed by oxygen plasma or ion bombardment, the mask removing step and the washing of the excitation part of step 77 may be performed at the same time.

When the cleaning of the exciting portions is completed, the etching liquid is supplied to each exciting portion by a syringe based on the dropping order of the etching liquid to each exciting portion and the dropping start time obtained in step 76. The second etching step is performed by shifting the etching start time of the portion (step 78). The supply amount of the etching liquid to the excitation unit in the second embodiment is controlled so that at least the entire excitation unit is wet and covered, and is as small as possible. FIG. 12 schematically shows the state of the second etching step in the second embodiment.

As shown in FIG. 12, the crystal wafer 12
Has a corrosion resistant film 34 made of Au / Cr on its surface. The quartz wafer 12 has the mask formed of the resist film on the corrosion resistant film 34 removed, and the excitation unit 1
4 is washed to remove organic substances, and the wettability of the excitation unit 14 is improved. The exciter 14 has an etching solution 18
Are supplied by a syringe not shown in the figure. The supply amount of the etching solution 18 is an amount that can wet and cover the entire excitation unit 14, and it is preferable that the supply amount is as small as possible, and at most, the level of the etching solution 18 is the crystal wafer 12.
It is desirable to be below the surface. A surfactant is added to the etching solution 18 to reduce the surface tension,
You may improve adsorption property. When the second etching process for each excitation part 14 is completed as described above, the excitation part of the quartz wafer is washed with pure water (step 7).
9), dry and send to the next step.

FIG. 13 is a diagram showing the result of adjusting the film thickness of the excitation portion by the method of manufacturing the piezoelectric vibrating piece according to the second embodiment. The sample used was the same as in the case of FIG.
The size of the concave portion forming the excitation portion 14 has a length of 3.4.
mm, the width is 1.8 mm, the depth is 0.046 mm, and the volume of the concave portion is 2.82 × 10 ⁻⁴ mL. Also, FIG.
In the case of 3 (2), after removing the resist on the surface of the crystal wafer, the excitation part 14 is washed by irradiation of ultraviolet rays to remove organic substances before the second etching step.
However, no surfactant is added to the etching solution.

In FIG. 13A, the frequency of each excitation unit 14 is measured by the network analyzer at the time when the first etching process is completed, and the measured frequency is 17
It shows how much it deviates from the reference frequency of 5.5 MHz. Further, in FIG. 2B, after removing the resist film, cleaning the excitation part, and further performing the second etching step to individually adjust the thickness of each excitation part 14, each excitation part 14 is similarly processed. Is measured and the amount of deviation from the reference frequency is obtained. In each case, the horizontal axis is the excitation unit 14.
And the vertical axis represents the frequency shift amount expressed in MHz. Each excitation unit 14 in the second etching process
The amount of etching liquid supplied to the chamber is 1.74 × 10 ⁻⁴ mL
The liquid level of the etching liquid is about 28 μm.

As shown in FIG. 13B, in the method of manufacturing the piezoelectric vibrating piece according to the second embodiment,
The film thickness can be adjusted with extremely high accuracy. That is, when the first etching process was completed, the standard deviation of the amount of deviation from the reference frequency was σ = 1.810, but in the second etching process of the second embodiment, the film thickness adjustment of the excitation part 14 was adjusted. Then, the standard deviation of the amount of deviation from the reference frequency is σ = 0.166, and precise film thickness adjustment can be performed.

In each of the embodiments, the concentration of the etching liquid 18 used in the manufacturing apparatus 10 is one, but
Without being limited to this form, for example, when a plurality of etching solutions 18 having different concentrations are prepared and the plate thickness of the excitation unit 14 measured by the network analyzer 26 is very thick with respect to the target value, High concentration etchant 18
Therefore, it is desirable that the etching time be shortened. By thus selecting the concentration of the etching solution 18 with respect to the thickness of the excitation part 14, the etching time of the entire wafer can be shortened.

By the way, the manufacturing apparatus 10 according to each embodiment
It is desirable to install in a thermostatic chamber or a thermostatic chamber where the temperature can be controlled reliably. If the apparatus is installed in a thermostatic chamber or a thermostatic chamber in this way, the liquid temperature of the etching liquid can be reliably controlled, and variations in the main vibration of the excitation unit can be minimized.

[0069]

As described above, according to the present invention, in the second etching step, by using the mask made of the resist film, the etching liquid can be easily held in the concave portion due to the liquid repellency of the mask. Therefore, it is not necessary to add a step such as attaching a thick plate to the wafer in the middle of the conventional manufacturing process, and moreover, the variation in the thickness of the excitation part formed by the first etching process which is the first etching can be surely and shortly made. In time, it can fit within a preset range. Further, according to the present invention, by removing the mask made of the resist film and performing the second etching step, it is possible to adjust the thickness of the excitation portion with extremely high accuracy by using an extremely small amount of etching solution.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a structure of a piezoelectric vibrating piece manufacturing apparatus according to an embodiment.

FIG. 2 is a flowchart showing a processing procedure of a control calculation unit according to the embodiment and a table showing a state of table calculation at each step.

FIG. 3 is an explanatory diagram showing a method of setting a dropping order and a dropping time of an etching solution in each of the excitation units according to the embodiment.

FIG. 4 is an explanatory diagram showing a measurement principle of a network analyzer.

FIG. 5 is an enlarged view of an essential part showing the structure of the pump body according to the present embodiment.

FIG. 6 is an enlarged cross-sectional view showing the structure of the pump main body instead of FIG.

FIG. 7 is an explanatory diagram showing a state of the etching liquid discharged from the dispenser.

FIG. 8 is a process explanatory view showing the manufacturing process of the quartz crystal resonator element according to the embodiment.

9 is a process explanatory view showing the manufacturing process of the quartz crystal resonator element according to the embodiment, which is a diagram illustrating a process following FIG. 8. FIG.

FIG. 10 is an explanatory diagram of a result of adjusting the thickness of the excitation portion by the method for manufacturing the piezoelectric vibrating piece according to the embodiment.

FIG. 11 is a flowchart illustrating a method of manufacturing a piezoelectric vibrating piece according to the second embodiment of the present invention.

FIG. 12 is an explanatory diagram of a second etching step in the second embodiment.

FIG. 13 is an explanatory diagram of a result of adjusting the thickness of the excitation portion by the method of manufacturing the piezoelectric vibrating piece according to the second embodiment.

[Explanation of symbols]

Reference numeral 10 ... Piezoelectric vibrating piece manufacturing apparatus, 12 ... Crystal wafer, 14 ... Excitation section, 16 ... Frequency measurement section, 18
……… Etching liquid, 20 ……… Liquid supply part, 22 …………
Arrows, 24 ......... Stage, 26 ......... Network analyzer, 28 ......... Probe, 30 ......... Robot arm, 32 ...... Cylinder device, 34 ......... Corrosion resistant film, 3
6 ... Stage, 38 ... Syringe, 40 ... Pump body, 40A ... Tube holder, 40B ... Tube, 40C ... Tube guide, 40E ... Cam convex portion, 40F ... ... guide surface, 42 ... ... robot arm, 44 ... ... transfer device, 46 ... ... control computing unit, 5
6 ... Piezoelectric element, 58 ... Thin plate portion, 60 ... Arrow, 62 ... Resist film, 64 ... Photomask.

Claims (15)

[Claims] 1. A method of manufacturing a piezoelectric vibrating piece, comprising forming a mask made of a resist film on the surface of a wafer, and etching the surface of the wafer exposed from an opening of the mask to form an exciting portion. The etching is divided into a first etching step and a second etching step, and the surface of the wafer exposed from the mask in the first etching step is collectively etched to form a plurality of excitation parts,
The frequency of each of the excitation parts is measured, and the etching time of each of the excitation parts is calculated based on the etching time of each of the excitation parts calculated so that the frequency of each of the excitation parts falls within a set range. A method of manufacturing a piezoelectric vibrating piece, wherein the second etching step is performed for each of the excitation parts at different start times. 2. The method of manufacturing a piezoelectric vibrating piece according to claim 1, wherein the supply amount of the etching liquid used in the second etching step is set to an amount that does not protrude from the opening of the resist film. 3. A first etching step of forming a mask made of a resist film on the surface of the wafer and then etching the surface of the wafer exposed from the opening of the mask to collectively form a plurality of excitation parts, A mask removing step of removing the mask from the surface of the wafer, and before or after this mask removing step, the frequencies of the respective exciting portions are measured, and the etching time for keeping the frequencies of the respective exciting portions within the set range is obtained. Second etching for etching the excitation part by shifting the etching start time of each excitation part so that the etching end points coincide with each other based on the time calculation step and the etching time of each excitation part obtained in this time calculation step A method of manufacturing a piezoelectric vibrating piece, comprising: 4. The supply amount of the etching liquid in the second etching step is at least an amount for covering the excitation part, and the liquid level of the etching liquid is below the surface of the wafer. Item 4. A method for manufacturing a piezoelectric vibrating piece according to Item 3. 5. The corrosion resistant film made of a conductive member is formed on the surface of the wafer, and the corrosion resistant film is grounded when the frequency of the excitation part is measured. 7. A method for manufacturing the piezoelectric vibrating piece according to. 6. The method of manufacturing a piezoelectric vibrating piece according to claim 1, wherein the second etching step is performed after cleaning the excitation part. 7. The method of manufacturing a piezoelectric vibrating piece according to claim 1, wherein a surfactant is added to the etching liquid used in the second etching step. 8. The method of manufacturing a piezoelectric vibrating piece according to claim 1, wherein the second etching step is performed using a plurality of etching solutions having different concentrations. 9. The supply of the etching solution used in the second etching step is performed by inserting the tip of the supply tube into the recess forming the exciting part and then growing a droplet of the etching solution at the tip of the supply tube. The method of manufacturing a piezoelectric vibrating piece according to any one of claims 1 to 8, wherein the droplet is brought into contact with the excitation unit. 10. The method of manufacturing a piezoelectric vibrating piece according to claim 9, wherein the position of the tip of the supply pipe is set at the central portion of the excitation unit. 11. A frequency measuring means for measuring a frequency of an exciting part formed on a surface of a wafer, and a control calculating part for calculating an etching time of each exciting part based on a value from the frequency measuring means. An apparatus for manufacturing a piezoelectric vibrating piece, further comprising: an etching liquid supply unit that shifts the time so that the etching end points coincide with each other based on the value from the control calculation unit and drops the etching liquid onto each excitation unit. . 12. The apparatus for manufacturing a piezoelectric vibrating piece according to claim 11, wherein the etching liquid supply means comprises a plurality of means, and the etching liquids having different concentrations can be dropped. 13. The method according to claim 11 or 12, wherein a tip of the etching liquid supply means is formed smaller than the exciting portion, and the tip can be inserted into a recess in which the exciting portion is formed. An apparatus for manufacturing the piezoelectric vibrating piece described. 14. The delivery of the etching liquid in the etching liquid supply means is provided with a deformable supply pipe for supplying the etching liquid and the supply pipe so as to sandwich the supply pipe. 14. The apparatus for manufacturing a piezoelectric vibrating piece according to claim 11, wherein the apparatus comprises a deformable rotating body. 15. The delivery of the etching liquid in the etching liquid supply means is constituted by an actuator using a piezoelectric element.
The apparatus for manufacturing a piezoelectric vibrating piece according to any one of claims 1 to 13.