JP5769557B2 - Method for manufacturing crystal resonator element - Google Patents

Description

  The present invention relates to a method of manufacturing a crystal resonator element having a vibration leg in which a groove is formed.

  In recent years, with respect to vibrators that are used as time standards for electronic devices, with the miniaturization of electronic devices in which they are used, vibrators that are small in size and have a small CI value (crystal impedance) are required. It has become so. As a method corresponding to this requirement, for example, in the case of a tuning-fork type crystal resonator piece, it is known that it is effective to form a groove in the vibration leg.

  Manufacture of a crystal resonator element having a vibration leg in which such a groove is formed is performed, for example, by the following process disclosed in Patent Document 1. 6 to 8 are views showing a conventional method for manufacturing a tuning-fork type crystal resonator element having a vibrating leg in which a groove is formed. These drawings show cross sections of two vibrating legs of a tuning-fork type crystal resonator element.

  First, as shown in FIG. 6A, the crystal substrate 1 is processed into a plate shape. Next, the chrome layer 3 and the gold layer 5 are formed on the front and back surfaces of the quartz substrate 1 (FIG. 6B). A photoresist layer 7 is formed on the gold layer thus formed (FIG. 6C). Next, the outer shape of the tuning fork crystal resonator piece is exposed and developed using a photomask, and patterned so that the photoresist layer 7 remains only inside the outer shape of the tuning fork crystal resonator piece. It is exposed (FIG. 6 (d)).

  Next, the exposed gold layer 5 is removed by etching (FIG. 7E). Subsequently, the remaining photoresist layer 7 is exposed to a groove and developed to remove the portion of the photoresist layer 7 corresponding to the groove (FIG. 8F). Next, the exposed chromium layer 3 is removed by etching (FIG. 7G). Next, the exposed quartz substrate 1 is etched with an etching solution for crystal etching (first etching step) (FIG. 7H). Subsequently, the gold layer 5 and the chromium layer 3 are sequentially removed by etching using the remaining photoresist layer 7 as a mask (FIG. 8 (i)).

  Next, the remaining photoresist layer 7 is peeled off (FIG. 8 (j)). Thereafter, the exposed quartz substrate 1 corresponding to the grooves is etched (second etching step), and grooves 9 having a predetermined depth are formed on both surfaces (FIG. 8 (k)). Finally, the remaining gold layer 5 and chromium layer 3 are peeled off to complete the shape of a tuning-fork type quartz resonator piece having a vibrating leg with a groove (FIG. 8 (l)). Thereafter, a tuning-fork type crystal resonator element having a vibrating leg in which an electrode is formed and a groove is formed is completed.

JP 2006-86925 A (page 5-7, FIG. 1-3)

However, the conventional manufacturing method as described above has the following problems. That is, the photoresist layer is damaged by the crystal etching solution in the first etching process. Therefore, when the gold layer and the chromium layer after the first etching process are etched, not only the gold layer and the chromium layer corresponding to the groove but also the damaged gold layer and the chromium layer of the photoresist layer are etched. Thus, there is a problem that the quartz substrate is exposed and the surface of the quartz resonator piece is damaged in the second etching step. If the surface of the quartz crystal resonator element is damaged, the shape balance of the vibrating legs is lost and the characteristics are deteriorated, or the electrodes are short-circuited, thereby deteriorating the yield.

  Accordingly, an object of the present invention is to improve the problems in the conventional method for manufacturing a vibrator element. An object of the present invention is to solve this problem and provide a method for manufacturing a crystal resonator element with a good yield by reducing damage to the surface of the crystal oscillator piece formed by etching.

Method for manufacturing a quartz oscillator piece of the present invention for solving the aforementioned problems is the method for manufacturing a quartz oscillator piece having a vibration legs having grooves formed, are laminated on the quartz substrate and the quartz substrate A first metal layer forming step of forming on the quartz substrate a first metal layer that acts as an intermediate layer for improving adhesion to the metal layer ; and forming a second metal layer on the first metal layer A second metal layer forming step, a resist layer forming step of forming a resist layer on the second metal layer, and processing the resist layer into a first resist pattern having a shape corresponding to the outer shape of the crystal resonator element A first resist layer processing step, a first metal layer processing step for processing the second metal layer into the first metal pattern using the first resist pattern as a mask, and the first resist pattern in the groove In addition to the second resist pattern having a shape corresponding to A second resist layer processing step of, in the second metal layer which is processed in the first metal pattern as a mask, the quartz substrate is etched, first etching step of processing the outer shape portion of the vibration legs And a second metal layer processing step of processing only the second metal layer into the second metal pattern using the second resist pattern as a mask, and a second metal layer processed into the second metal pattern A second etching step of etching the first metal layer and the quartz crystal substrate at a time using the mask to process the groove portion of the vibration leg and the outer shape portion remaining in the first etching step. Features.

  In addition to the above-described configuration, the method for manufacturing a quartz crystal resonator element according to the present invention includes a first metal layer processed into a first metal pattern as a mask in the first etching step. The metal layer and the quartz substrate are simultaneously etched to process the outer portion of the vibration leg.

  In addition to the above-described configuration, the method for manufacturing a crystal resonator element according to the present invention is characterized in that the first metal layer is a chromium layer.

  Furthermore, the method for manufacturing a crystal resonator element according to the present invention is characterized in that, in addition to the above-described configuration, the second metal layer is a gold layer.

  In the method for manufacturing a crystal resonator element according to the present invention, the outer shape and groove shape of the vibrating leg of the crystal element are formed in the first etching step and the second etching step. Here, the outer shape of the vibration leg is determined by the total etching time of the first etching step and the second etching step.

  Further, in the method for manufacturing a crystal resonator element according to the present invention, in the second etching step, the first metal layer and the crystal substrate are etched at a time to process the outer portion and the groove portion of the vibration leg. Compared with the conventional etching process in which only the quartz substrate is etched to process the outer portion and the groove portion, the etching time required for processing the predetermined groove shape becomes longer. For this reason, in this invention, the etching time which a 2nd etching process requires becomes long, and it can shorten the time which a 1st etching process requires by that much.

This can reduce damage to the second resist pattern in the first etching step, reduce damage to the second metal pattern in the second metal layer processing step, and use the second metal pattern as a mask. Thus, damage to the surface of the crystal resonator piece formed by etching can be reduced, and the yield can be improved.

It is explanatory drawing which shows the manufacturing process of the vibrator element by the manufacturing method of this invention as order of a process as (a)-(d) figure. It is explanatory drawing which shows the manufacturing process continuous to the process of FIG. 1 in order of a process as (e)-(h) figure. It is explanatory drawing which shows the manufacturing process continuous to the process of FIG. 2 in order of a process as (i)-(l) figure. It is a figure which shows the external shape of the tuning fork type | mold crystal vibrator piece which has the vibration leg in which the groove | channel formed by the manufacturing method by this invention was formed. It is a figure which shows the tuning fork type | mold crystal vibrator piece which has the vibration leg in which the groove | channel manufactured by the manufacturing method by this invention was formed. It is explanatory drawing which shows the manufacturing process of the vibrator element by the conventional manufacturing method in order of a process as (a)-(d) figure. It is explanatory drawing which shows the manufacturing process continuous to the process of FIG. 6 in order of a process as (e)-(h) figure. It is explanatory drawing which shows the manufacturing process continuous to the process of FIG. 7 in order of a process as (i)-(l) figure.

The best mode for carrying out the present invention will be described below with reference to the drawings.

  1 to 3 are diagrams showing a manufacturing process of the vibrator element according to the present invention. These drawings show cross sections of two vibrating legs of a tuning-fork type crystal resonator element.

  First, as shown in FIG. 1A, the crystal substrate 1 is processed into a plate shape. Next, the chromium layer 3 which is a 1st metal layer is formed into a film as a base layer on both front and back surfaces of the quartz substrate 1 by vapor deposition or sputtering (1st metal layer formation process). The chromium layer 3 as the first metal layer functions as an intermediate layer for improving the adhesion between the gold layer 5 as the second metal layer described later and the quartz substrate 1. Here, the chromium layer 3 is an example of a first metal layer, and another metal layer having the same function may be used.

  Subsequently, a gold layer 5 is formed as a second metal layer on the chromium layer 3 (second metal layer forming step) (FIG. 1B). The gold layer 5 as the second metal layer acts as a corrosion-resistant film against a mixed solution of hydrofluoric acid and ammonium fluoride solution used when etching the crystal in a process described later. Here, the gold layer 5 is an example of a second metal layer, and another metal layer having the same function may be used.

  Next, a photoresist is applied to the surface of the gold layer 5 and dried to form a photoresist layer 7 (resist layer forming step) (FIG. 1C). As the photoresist, for example, TSMR (registered trademark) manufactured by Tokyo Ohka, which is a positive photoresist, is used.

  Next, exposure and development are performed using a photomask for forming the outer shape of the crystal resonator element, so that the photoresist layer 7 remains only inside the outer shape of the crystal oscillator element, and the outer gold layer 5 is exposed. (First resist layer processing step) (FIG. 1D). Next, the exposed gold layer 5 is removed by etching (first metal layer processing step) (FIG. 2E). The chromium layer 3 is exposed at the portion where the gold layer 5 is removed.

  Subsequently, the remaining photoresist layer 7 is exposed to a groove, developed, and the photoresist layer 7 corresponding to the groove is removed (second resist layer processing step) (FIG. 2f)) . At this time, the gold layer 5 is exposed at a portion corresponding to the groove from which the photoresist layer 7 has been removed. Next, the exposed chromium layer 3 is removed by etching (FIG. 2G).

  Next, the exposed quartz substrate 1 is etched using a mixed solution of hydrofluoric acid and an ammonium fluoride solution, which is a quartz etching solution (first etching step) (FIG. 2H). In this figure, the exposed quartz substrate 1 is penetrated by etching, but it is not always necessary to penetrate in the first etching step.

  Subsequently, the gold layer 5 exposed at the portion corresponding to the groove is removed by etching (second metal layer processing step) (FIG. 3I). At this time, the chromium layer 3 is exposed at a portion corresponding to the groove. Next, the remaining photoresist layer 7 is peeled off (FIG. 3 (j)). Thereafter, etching is performed using a mixed solution of hydrofluoric acid and ammonium fluoride (second etching step). At this time, as the crystal etching corresponding to the outer shape of the vibrator piece proceeds, the chrome layer 3 is etched in the portion corresponding to the groove, and after the chrome layer 3 is removed, the crystal is etched, and both the upper and lower surfaces are etched. A groove 9 having a predetermined depth is formed (FIG. 3 (k)). Finally, the gold layer 5 and the chrome layer 3 are removed, and the shape of the crystal resonator element having the vibration leg in which the groove is formed is completed (FIG. 3L).

  Thus, in the present invention, the second etching process is performed while leaving the chromium layer 3 in the portion corresponding to the groove. By performing the second etching while leaving the chromium layer 3 in the portion corresponding to the groove, the time required for the second etching step becomes longer. Since the crystal etching time for forming the outer shape of the resonator element is determined by the total time of the first etching step and the second etching step, the first etching step can be performed by increasing the time of the second etching step. The time for the etching process 1 can be shortened.

  This can reduce damage to the second resist pattern in the first etching step, reduce damage to the second metal pattern in the second metal layer processing step, and use the second metal pattern as a mask. It is possible to reduce damage to the surface of the crystal resonator element in the second etching process.

  The number of grooves formed in the vibrating leg and the shape of the grooves are determined according to the design of the vibrator. As the width of the groove in the second resist pattern is narrower, the manufacturing method of the present invention in which the second etching step is performed in a state where the chromium layer 3 is left in the portion corresponding to the groove, and the chromium layer 3 is removed and the second etching process is performed. The difference in time required for the second etching step with the conventional manufacturing method that performs the etching step can be increased. Further, the thicker the chromium layer 3 is, the longer the second etching process can be.

  The width of the groove in the second resist pattern is preferably 1 to 10 μm, for example. Here, the lower limit of the width of the groove is determined by exposure and development conditions, and may be narrower than 1 μm as long as the resist pattern can be stably formed. If the width of the groove is too wide, there is no time difference between the second etching process in the manufacturing method of the present invention and the conventional manufacturing method, and the effect cannot be obtained. The thickness of the chromium layer 3 is preferably 10 to 100 nm, for example. If the chromium layer 3 is too thin, the adhesion between the gold layer 5 and the quartz substrate 1 is deteriorated. On the other hand, if the chromium layer 3 is too thick, the vibration characteristics of the crystal resonator are deteriorated.

Further, if the temperature of the mixed solution of hydrofluoric acid and ammonium fluoride solution, which is a crystal etching solution, is too low, the chromium layer 3 corresponding to the groove is not uniformly removed in the second etching step. The temperature of the etching solution is desirably 60 ° C. or higher. For example, when the temperature of the etching solution for quartz is 70 ° C., the groove width in the second resist pattern is 2 μm, and the thickness of the chromium layer 3 is 20 nm, the second necessary for forming a groove having a depth of 70 μm. The etching process takes 280 minutes in the manufacturing method of the present invention and 215 minutes in the conventional manufacturing method.

  In the manufacturing process of the present invention described above, after the second resist layer processing step, the first etching step is performed after removing the chromium layer 3 exposed outside the outer shape of the crystal resonator element. The outer area of the outer shape of the quartz crystal resonator piece is sufficiently large as compared with the groove of the vibrating leg, and the effect on the time required for the first etching process is small even if the chromium layer 3 is left. The first etching may be performed without removing 3.

  Further, in general, in the etching of chromium, the amount of side etching is likely to change depending on the number of times the etching solution is used, and thus the shape tends to vary. In particular, the influence of a change in the side etching amount is large in a thin portion such as a groove of a vibrating leg. As in the present invention, by not performing the chrome etching of the portion corresponding to the groove of the vibration leg, the variation in the groove shape can be suppressed. Furthermore, the amount of the chromium etching solution used can be reduced, and the cost can be reduced.

  In the manufacturing process of the present invention described above, the second etching process is performed after the photoresist layer 7 is removed after the second metal layer processing process for removing the gold layer 5 corresponding to the groove. However, it is also possible to perform the second etching process while leaving the photoresist layer 7 and then peel the photoresist layer 7.

  In this way, the outer shape of the tuning-fork type crystal resonator element having the vibration legs in which grooves as shown in FIG. 4 are formed is completed. A tuning-fork type crystal resonator element having a vibrating leg formed with a groove is composed of a base 11 and two legs 13 extending from the base 11, and a groove 9 is provided on the front and back surfaces of the leg 13.

  Next, a process for forming the electrode 15 shown in FIG. 5 will be described. FIG. 5 is a plan view of a tuning-fork type crystal resonator element having a vibration leg in which a groove is formed. The electrodes 15 are provided on the groove portion 9, the side surface, and the base portion 11 of the leg 13, respectively. First, a metal layer is formed on the entire surface of a tuning-fork type quartz resonator piece having a vibrating leg in which grooves are formed, and then a photoresist layer is formed on the surface of the metal layer. At this time, since it is necessary to apply the photoresist three-dimensionally on the front, back, and side surfaces of the tuning fork type crystal resonator piece, the electrodeposition photoresist can be applied using a spray coating method using a spray coating apparatus or a metal layer as an electrode. An electrodeposition coating method is used. Next, the electrode pattern is exposed and developed, and the photoresist layer corresponding to the portion where the electrode 15 in FIG. 5 is not formed is removed. Next, if the metal film of the part exposed on the surface is removed by etching and the photoresist layer is peeled off, an electrode 15 as shown in FIG. 5 is formed.

  In the best mode for carrying out the present invention described above, an example of a tuning fork type crystal resonator element having a vibrating leg with a groove is shown. It is apparent that the present invention can be applied to a crystal resonator element having a vibration leg in which a groove is formed.

1 Quartz substrate 3 Chrome layer 5 Gold layer 7 Photoresist layer 9 Groove 11 Base 13 Leg 15 Electrode

Claims (4)

In the method of manufacturing a crystal resonator element having a vibration leg in which a groove is formed,
A first metal layer forming step of forming on the crystal substrate a first metal layer that acts as an intermediate layer for improving adhesion between the crystal substrate and a metal layer laminated on the crystal substrate;
A second metal layer forming step of forming a second metal layer on the first metal layer;
A resist layer forming step of forming a resist layer on the second metal layer;
A first resist layer processing step of processing the resist layer into a first resist pattern having a shape corresponding to the outer shape of the crystal resonator element;
A first metal layer processing step of processing the second metal layer into a first metal pattern using the first resist pattern as a mask;
A second resist layer processing step for processing the first resist pattern into a second resist pattern having a shape corresponding to the groove;
And the second metal layer which is processed to the first metal pattern as a mask, the quartz substrate is etched, a first etching step of processing the outer shape portion of the vibrating leg,
A second metal layer processing step of processing only the second metal layer into a second metal pattern using the second resist pattern as a mask;
Using the second metal layer processed into the second metal pattern as a mask, the first metal layer and the quartz substrate are etched at a time, and the groove portion of the vibrating leg and the first etching are etched. And a second etching step of processing the outer shape portion remaining in the step . A method of manufacturing a crystal resonator element, comprising: In the first etching step, the first metal layer and the quartz substrate are simultaneously etched using the second metal layer processed into the first metal pattern as a mask, and the outer shape of the vibration leg The method for manufacturing a crystal resonator element according to claim 1, wherein the portion is processed. The method for manufacturing a crystal resonator element according to claim 1, wherein the first metal layer is a chromium layer. The method for manufacturing a crystal resonator element according to claim 1, wherein the second metal layer is a gold layer.

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