JP6185744B2 - Manufacturing method of tuning fork crystal unit - Google Patents

Description

  The present invention relates to a method for manufacturing a tuning fork crystal unit used in an oscillation circuit such as a cellular phone.

  In the wet etching process of the tuning fork type crystal resonator, conventionally, for example, in the quartz etching process, the etching rate of a quartz etching tank is measured in advance, and the measured value of this etching rate is used to determine the target branch width dimension. The crystal etching time corresponding to the difference was calculated to determine the crystal etching time.

  Further, as described in Japanese Patent Application Laid-Open No. 2002-33639, a dummy pattern is formed in a quartz wafer forming a tuning fork type crystal resonator, and the amount of change in the width W of the dummy pattern due to etching is measured. Also known is a method of calculating the crystal etching time and determining the crystal etching time.

JP 2002-33639 A

  When calculating the crystal etching time for crystal etching, the conventional technique measures the branch width before crystal etching and assumes that the etching rate of the tank in which crystal etching is performed is constant each time. The crystal etching time was determined from the etching rate of the tank assumed in advance.

  However, in practice, the specific items assumed that the etching rate of the tank is constant each time include the etching temperature for crystal etching, for example, the temperature and concentration of buffered hydrofluoric acid, the displacement of the crystal etching tank, the crystal etching tank There are ambient temperature and humidity, etc., and it is difficult to manage all of the above items constantly. Therefore, the etching rate of the tank for performing crystal etching is not constant every time.

As described above, in the prior art, the etching rate of the tank for performing the crystal etching is not constant every time, so that the processing accuracy is poor, and the variation in the branch width after the crystal etching becomes large. When the variation in the branch width dimension becomes large, the frequency of the tuning fork type crystal resonator does not fall within the standard and becomes defective. Further, even if the frequency falls within the standard, the processing time becomes long and the manufacturing time becomes long in the process of adjusting the frequency of the tuning fork type crystal resonator after the crystal etching process.

In addition, in the prior art, as shown in FIG. 3, during crystal etching, before the target branch width dimension is obtained, the wafer is temporarily taken out, washed, washed and dried, and then the branch width is measured and added. There is a method of deciding the etching time of this, and there is also a method of repeating this operation a plurality of times to bring it closer to the target branch width dimension, but this has a drawback, and firstly, for performing the above work Second, when the branch width is measured, the branch width is measured from the top of the resist film formed on the crystal plane, and thus cannot be measured accurately. Note that if the resist film and the corrosion-resistant film formed on the quartz surface are peeled off and then formed again, the branch width can be measured accurately. It will be disadvantageous. As described above, due to the problems of man-hours and accuracy, in the conventional method, the processing accuracy is poor, and the variation in branch width after crystal etching becomes large.

An object of the present invention is to easily calculate an etching rate in a crystal etching process of a tuning fork type crystal resonator.

  The present invention is a method for manufacturing a crystal resonator, in which a tank etching rate that varies each time is measured simply and accurately, and a crystal etching time is calculated from the tank etching rate.

In the manufacturing method of crystal etching processing of the tuning fork crystal unit wet process, the thickness of the etching rate measurement dedicated wafer is measured, and the measurement dedicated wafer is etched simultaneously with the crystal wafer forming the tuning fork crystal unit. After a certain period of time, pull up the measurement-dedicated wafer, measure the thickness of the measurement-dedicated wafer, and determine the etching rate in the thickness direction from the amount of change in the thickness of the measurement-dedicated wafer and the etching time. calculated and, a method for producing a sound or crystal oscillator for determining the crystal etching time.

Tuning fork crystal oscillator, a method for manufacturing a tuning-fork crystal that having a least one groove in the vibrating arms.

  The measurement of the plate thickness dimension for obtaining the etching rate in the plate thickness direction, which is the main point of the present invention, can be easily measured with a laser beam or the like and can be performed in a short time. The management of the crystal etching time of the etching rate can be easily performed. In the present invention, it is possible to easily and accurately calculate the etching rate of the tank, which has been a problem in the prior art, to reduce the variation in the branch width after the crystal etching, and to keep the frequency of the crystal resonator within the standard. In addition, in the process of adjusting the frequency of the crystal resonator after the crystal etching process, the processing time is shortened, and the overall manufacturing time can be shortened.

The figure explaining the correlation of the etching rate in this invention The figure explaining the change of the plate | board thickness of the measurement exclusive wafer in this invention Schematic explaining conventional branch width measurement Perspective view of grooved tuning fork crystal unit The figure explaining the process before putting crystal etching of the wafer

    The steps up to the state before the crystal etching of the crystal wafer used in Examples 1 and 2 will be described below with a generally known method of a tuning fork type crystal resonator (see FIG. 5). First, a quartz wafer 1 having a predetermined thickness is prepared. A corrosion-resistant film is formed on the first main surface and the second main surface of the crystal wafer 1 by a method such as sputtering. For the corrosion resistant film, for example, gold is used and the base is made of chromium. Next, resist coating is performed on the first main surface and the second main surface on which the corrosion-resistant film is formed by a method such as spin coating. Next, the external pattern of the tuning fork type crystal resonator drawn on the mask is exposed on the first main surface and the second main surface. Next, an external pattern of the exposed tuning fork type crystal resonator is formed using a developer. Furthermore, the gold layer 3 and the chromium layer 2 exposed from the resist 4 are etched using, for example, an aqueous solution of iodine and potassium iodide and an aqueous solution of ceric ammonium nitrate and acetic acid, respectively. By etching the gold layer 3 and the chromium layer 2, an outer pattern of a tuning fork type crystal resonator is formed on the corrosion-resistant film.

First, the condition of the crystal etching tank, for example, the temperature of buffered hydrofluoric acid that is an etching liquid for etching the crystal wafer is set to a desired condition so that the crystal wafer can be put into the crystal etching tank.

  Next, a dedicated wafer for etching rate measurement in the plate thickness direction is prepared, and the plate thickness dimension t1 is measured (see FIG. 2). For example, the thickness of the plate is measured using a laser beam.

The wafer whose thickness was measured is put into the crystal etching tank at the same time as the crystal wafer to be put into the crystal etching tank. After the measurement-specific wafer and the crystal wafer are etched for a certain time, for example, 600 seconds, only the measurement-specific wafer is lifted from the crystal etching tank, washed, washed, and dried, and then the thickness t2 is measured ( (See FIG. 2). The quartz wafer is etched as it is without being lifted from the quartz etching tank.

As shown in FIG. 1, since there is a correlation between the etching rate in the plate thickness direction and the etching rate in the branch width direction, the etching rate in the plate thickness direction is determined from the amount of change in the plate thickness dimension of the measurement-dedicated wafer and the etching time. It is calculated and converted into an etching rate in the branch width direction of the crystal wafer. During this period, that is, from the pulling up of the measurement dedicated wafer to the measurement of the plate thickness dimension and the calculation of the etching rate in the branch width direction, the crystal wafer is being etched, so the remaining crystal etching is performed from the etching rate calculated from the measurement dedicated wafer. Decide on time. The longer the etching time of the measurement-dedicated wafer is, the more accurately the etching rate can be calculated.

The crystal wafer is etched in the crystal etching tank for the remaining etching time, and after a predetermined time, the crystal wafer is pulled up from the crystal etching tank. By determining the crystal etching time in this manner, the variation in the branch width after crystal etching is reduced, so that the frequency of the crystal resonator can be kept within the standard. In the process of adjusting the frequency of the vibrator, the processing time is shortened, and the overall manufacturing time can be shortened.

  In the first embodiment, the plate thickness measurement dedicated wafer was put into the crystal etching tank simultaneously with the crystal wafer, and the etching rate was calculated. In the second embodiment, when the etching time of the crystal wafer was short, the crystal Before the wafer is put into the crystal etching tank, the etching rate is calculated with a wafer dedicated to thickness measurement.

First, the condition of the crystal etching tank, for example, the temperature of buffered hydrofluoric acid that is an etching liquid for etching the crystal wafer is set to a desired condition so that the crystal wafer can be put into the crystal etching tank. Next, a dedicated wafer for etching rate measurement in the plate thickness direction is prepared, and the plate thickness dimension is measured.

Before the quartz wafer is put into the quartz etching tank, the wafer whose thickness is measured is put into the quartz etching tank. After the measurement-dedicated wafer is etched for a certain period of time, for example, 600 seconds, the plate thickness is measured after being pulled out of the crystal etching tank, washed, washed and dried.

Similar to Example 1, since the etching rate in the plate thickness direction and the etching rate in the branch width direction are correlated, the etching rate in the plate thickness direction is determined from the amount of change in the plate thickness dimension of the measurement-dedicated wafer and the etching time. It is calculated and converted into the etching rate in the branch width direction of the crystal wafer, and the etching time before putting the crystal etching tank is determined. It should be noted that the longer the etching time of the measurement-dedicated wafer, the more accurately the etching rate can be calculated.

  In the first and second embodiments, the outer shape of the tuning fork crystal unit is described. However, the present invention is not limited to the outer shape of the tuning fork type crystal unit, and the grooved tuning fork type crystal unit as shown in FIG. The present invention can also be applied to groove formation etching on a child tuning fork arm.

  Similar to the variation in the branch width dimension, the characteristics deteriorate as the variation in the groove dimension increases. Therefore, by using the present invention, it becomes possible to easily calculate the etching time of the groove formation etching, and the groove dimension (groove width).・ Variations in groove depth can be reduced, and the characteristics of a tuning-fork crystal unit with grooves can be kept within the specifications.

DESCRIPTION OF SYMBOLS 1 Crystal wafer 2 Cr layer 3 Au layer 4 Resist 5 Tuning fork arm 6 Groove 10 Crystal oscillator

Claims (2)

In the manufacturing method of the crystal etching processing of the tuning fork type crystal resonator wet process, the thickness of the etching rate measurement dedicated wafer is measured, and the measurement dedicated wafer is crystallized simultaneously with the crystal wafer forming the tuning fork crystal resonator. Etching is performed, and after the elapse of a certain time, the measurement-dedicated wafer is pulled up, and the thickness dimension of the measurement-dedicated wafer is measured. A method for manufacturing a tuning fork type crystal resonator, comprising: calculating an etching rate in a thickness direction to determine a crystal etching time. The method of manufacturing a tuning-fork type crystal oscillator according to claim 1, wherein the tuning fork crystal oscillator, manufacturing method of the tuning fork type crystal oscillator according to claim Rukoto that having a least one groove in the vibrating arms.

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