JP2001345656A - Method of manufacturing crystal vibrator and crystal device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a crystal vibrator containing a component diffused and mixed in an electrode film enough to block solder from diffusing, and a crystal device using a crystal vibrator having such characteristics. SOLUTION: A crystal vibrator 11 comprises a drive electrode 19 for applying a drive voltage, and connecting electrodes 13, 14 connected through leading electrodes 14a to the drive electrode on the surface of a crystal 21. A feed electrode 17a is bonded to the connecting electrodes for applying the drive voltage from the outside, and the crystal is formed from a crystal block. An electrode film 25 is composed of a Cr base layer 22, an intermediate layer 23 made of a mixture of copper with a conductive metal on the base layer, an upper layer 24 made of the conductive metal on the intermediate layer on the surface of the crystal piece. The connecting electrodes of the electrode film are butted to the feed electrode, soldered and heat treated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a method for manufacturing a crystal resonator element housed in a package of a crystal device, and to a crystal device using the crystal resonator element by such a manufacturing method.

[0002]

2. Description of the Related Art FIG. 18 is a flowchart schematically showing a conventional manufacturing process for manufacturing a crystal resonator element used for a crystal device such as a crystal resonator.

In the figure, first, a rough quartz crystal obtained by a predetermined crystal growth process is cut as a piezoelectric material that generates vibration by applying a voltage, thereby forming a quartz wafer. Then, the quartz wafer is polished to increase the parallelism of the front and back surfaces of the wafer, and is adjusted to a predetermined thickness. Then, the crystal wafer after processing is cut to have a chip size for forming a crystal vibrating piece,
The cut end face is polished to obtain a crystal piece (ST1).

Next, the surface (both front and back) of this crystal blank
Next, an electrode film is formed by vapor deposition or the like. That is, in order to form an electrode on a quartz crystal piece which is a piezoelectric body and generate a predetermined vibration, an excitation electrode and an external electrode for supplying a drive voltage from the outside to the excitation electrode are connected to the surface thereof. Electrodes are provided (ST2).

FIG. 19A shows a film structure of the electrode film 8. On the crystal blank 2, first, C
r is deposited by vapor deposition or the like, and an electrode layer 4 of, for example, silver is formed thereon as an upper layer.

Next, as shown in FIG. 21, the power supply electrode 6, which is an external electrode, is joined by using solder (ST3), and subsequently, an annealing process is performed to apply an internal stress applied up to this joining step. Is removed (ST4).

Then, the mass of the electrode film 8 formed in ST2 is adjusted, that is, the components of the electrode layer 4 are added and weighted, or an electron beam, an ion beam, or a laser beam is irradiated. The frequency is adjusted so that the metal film of the electrode layer 4 is delicately removed to reduce the mass (ST).
5). In other words, for a desired frequency of the quartz vibrating piece,
The actual vibration frequency is adjusted to match the desired vibration performance.

When the frequency adjustment is completed, the crystal resonator element is sealed in a package in a vacuum or nitrogen atmosphere to complete the crystal resonator (ST6). Then, in the case of surface mounting, the crystal unit is further resin-molded (ST7).
At this time, heating stress is applied to the crystal vibrating piece.

[0009]

By the way, in the case of a piezoelectric device using the piezoelectric vibrating reed manufactured by the above-described manufacturing process, as shown in FIG. 20, the product is placed in a high temperature environment, for example, 125 degrees Celsius. Under such an environment, there is a problem that the vibration frequency changes.

In this case, the vibration frequency of the piezoelectric vibrating piece changes so as to be lower. As a result, there is a problem that desired vibration performance cannot be maintained.

As a cause of such a variation, the above-described problem in the manufacturing process can be considered.

That is, if heat is applied to the piezoelectric vibrating reed (ST4 to ST7) after the soldering step of the power supply electrode (lead) 6 in ST3, it is considered that the process shown in FIG. 21 proceeds. First, the power supply electrode 6 is joined by diffusing the solder component to the surface of the electrode film 8 by heat. However, when this solder component is placed in a high-temperature environment in the above-described manufacturing process such as the annealing process of ST4 or the molding process of ST7 after bonding, as shown by an arrow in FIG. It spreads further.

In this case, the diffused solder component increases the weight of the electrode film 8, resulting in a change in frequency as described above, which has an adverse effect.

As shown in FIG. 19B, at this high temperature, the chromium component of the underlayer 3 also diffuses into the upper electrode layer 4 in contact with the underlayer 3 to form a diffusion layer 5. However, the surface of the electrode layer 4 is hardly affected.

Here, it has been found that when a high melting point metal component such as chromium is diffused into the electrode layer 4, the diffusion of the solder component can be prevented. However, FIG.
In the structure of the electrode film 8 as shown in (a), the chromium component diffuses only in the vicinity of the region where the underlayer 3 contacts, while the solder component is Therefore, the effect of suppressing the solder diffusion as described above due to the diffusion of chromium cannot be expected.

Therefore, in the electrode film structure shown in FIG. 19A, a method of providing an intermediate layer (not shown) between the underlayer 3 and the upper layer 4 and making the intermediate layer contain the chromium component is also conceivable. .

Therefore, such an attempt was specifically studied. As a result, such an intermediate layer in which a chromium component was mixed with a conductive metal was provided, and the chromium component was sufficiently diffused into the upper layer. And the above frequency change is 5pp
In order to suppress the chromium content to about m, the chromium content of the intermediate layer must be at least 4% in atomic weight.

However, with such a film structure, CI
(Crystal impedance) value increases,
It is necessary that the film thickness be 1500 nm or more. If the chromium component is sufficiently diffused into the upper layer in order to suppress the frequency change as described above, another problem that the solder flow becomes insufficient occurs. The present invention solves the above-mentioned problems, and a method of manufacturing a crystal vibrating piece capable of preventing a deterioration in vibration characteristics by sufficiently diffusing and mixing a component capable of preventing the diffusion of a solder component in an electrode film. It is an object of the present invention to provide a crystal device using a crystal resonator element having such characteristics.

[0019]

According to the first aspect of the present invention, there is provided an excitation electrode to which a driving voltage is applied to the surface of a crystal blank, and a connection which is connected to the excitation electrode via an extraction electrode. A method for manufacturing a crystal vibrating reed in which a power supply electrode for applying a driving voltage from the outside is joined to the connection electrode, wherein the crystal wafer is obtained by cutting a crystal block. A crystal blank is formed, and on the surface of the crystal blank, an underlayer made of one of Ti, Cr and Ni, and an intermediate layer provided on the underlayer and made of a mixed layer of Cu and a conductive metal. Forming an electrode film provided on the intermediate layer and having an upper layer made of the conductive metal, contacting the power supply electrode with a connection electrode of the electrode film, joining the power supply electrode with solder, and then performing heat treatment. By the bonding process, And the material component of the intermediate layer is diffused into the upper layer and deposited on the surface of the upper layer, and further, the surface of the electrode film is subjected to a mass increase or mass reduction process. This is achieved by a method for manufacturing a crystal vibrating piece, which adjusts the frequency by using the above method.

According to the first aspect of the present invention, the quartz vibrating reed by this manufacturing method is composed of Ti, C
an underlayer made of one of r and Ni, an intermediate layer provided on the underlayer, and made of a mixed layer of Cu and a conductive metal;
An upper layer provided on the intermediate layer and made of the conductor metal.

Then, the power supply electrode is brought into contact with the connection electrode of the electrode film and bonded by soldering, and then heat-treated to relieve the stress applied to the crystal blank by the bonding step and to reduce the stress applied to the intermediate piece. The material components of the layer are diffused into the upper layer and deposited on the surface of the upper layer.

That is, in the present invention, the components of the underlayer are selected from one of Ti, Cr and Ni, but these components are not expected to diffuse into the upper layer. In other words, it is not intended to obtain the effect of preventing the diffusion of solder by diffusing these components into the conductive metal of the upper layer, and the components of the base layer are suitable for bonding the crystal and the conductive metal. Are selected.

On the other hand, as a result of various studies on conditions for actively diffusing an effective component other than the refractory metal in the thickness direction of the electrode film, an intermediate layer comprising a mixed layer of the Cu component and the conductive metal was found. And actively performing heat treatment after the bonding step.

That is, placing the device in a high temperature environment after manufacturing or after forming the electrode film leads to diffusion of the solder component used for bonding into the electrode film as described above. Therefore, the addition of a simple heat treatment step does not solve the problem. The present inventors have studied various conditions for preventing the diffusion of solder while introducing a heat treatment step for diffusion of components other than the high melting point metal component, and in the present invention, as described above, This was achieved by devising a heat treatment process in which an intermediate layer was provided and the Cu component of the intermediate layer was positively deposited on the electrode layer.

Thus, C deposited to the surface of the electrode film
Because of the presence of the u component, C
It is considered that the u component is mixed. Accordingly, the solder component is not easily diffused along the electrode film surface even in a high temperature environment in a subsequent mounting step or the like, and the diffused solder component does not increase the weight of the electrode film.

Moreover, since the Cu component mixed enough to precipitate on the surface of the electrode film does not increase the CI value, it is not necessary to take measures for increasing the CI value, and there is another problem other than the solder diffusion. Does not occur.

According to a second aspect of the present invention, there is provided an excitation electrode for applying a drive voltage to the surface of a crystal blank, and a connection electrode connected to the excitation electrode via a lead electrode. A method for manufacturing a crystal vibrating reed in which a power supply electrode for applying an external drive voltage is connected to a connection electrode, wherein the crystal reed is formed from a crystal wafer obtained by cutting a crystal block, Ti, C on the surface of this crystal blank
an underlayer made of one of r and Ni, an intermediate layer provided on the underlayer, and made of a mixed layer of Cu and a conductive metal;
Forming an electrode film provided on the intermediate layer and having an upper layer made of the conductive metal, contacting the power supply electrode with a connection electrode of the electrode film and joining it by soldering, and further forming at least the excitation electrode On top, an outermost surface layer of Al is formed, and then, by heat treatment, the stress applied to the crystal blank before the bonding step is relaxed, and the material component of the intermediate layer is diffused into the upper layer. A crystal vibrating piece that is deposited on the surface of the upper layer, diffuses Al of the outermost surface layer into the upper layer, and further adjusts the frequency by performing a mass increase or mass reduction process on the surface of the electrode film. Is achieved.

According to the structure of the second aspect, the quartz-crystal vibrating piece is provided on the underlayer made of one of Ti, Cr and Ni, as in the first aspect of the invention. And
Al is formed on the upper layer of at least the excitation electrode portion of the electrode film having an intermediate layer formed of a mixed layer of Cu and a conductive metal, and an upper layer provided on the intermediate layer and formed of the conductive metal. Is different from the configuration of claim 1 in that the outermost layer is provided.

Here, aluminum (Al) is selected as the outermost surface layer because Al is formed on a conductive metal,
In addition, by diffusing Al into the conductor metal (Ag or Au), diffusion of the solder into the conductor metal can be suppressed;
A weight layer is formed on the excitation electrode before the frequency adjustment step in order to increase the mass in advance before the frequency adjustment step, but at this time, the adhesion between the conductor metal and the weight layer is prevented. This is because the layer can play a role.

After the formation of the outermost surface layer, heat treatment is actively performed to diffuse the material components of the outermost surface layer into the upper layer below the outermost layer. The component diffuses upward from the intermediate layer, and the Al component diffuses downward from the outermost surface layer in the thickness direction.

Thus, an effect exceeding the first aspect is exhibited, and diffusion of the solder component into the electrode film (upper layer) is suppressed.

According to the third aspect of the present invention, there is provided an excitation electrode for applying a drive voltage to a surface of a crystal blank,
A method for manufacturing a quartz vibrating reed, comprising: a connection electrode connected via an excitation electrode and an extraction electrode; and a power supply electrode for applying an external drive voltage to the connection electrode. The crystal blank is formed from a crystal wafer obtained by cutting a crystal block, and the surface of the crystal blank is
an underlayer made of one of i, Cr, and Ni; an intermediate layer provided on the underlayer, which is a mixed layer of Cu and a conductive metal; and an intermediate layer provided on the intermediate layer. Forming an electrode film having an upper layer consisting of: an upper layer made of Al, a power supply electrode is brought into contact with a connection electrode of the electrode film and joined by soldering, and at least on the extraction electrode, an outermost surface layer of Al is formed; Next, by performing a heat treatment, the stress applied to the crystal blank until the bonding step is reduced, and
While diffusing the material component of the intermediate layer into the upper layer and depositing it on the surface of the upper layer, Al of the outermost surface layer is diffused into the upper layer, and further, with respect to the surface of the electrode film,
This is achieved by a method of manufacturing a crystal vibrating piece that adjusts the frequency by performing a mass increase or mass reduction process.

According to the third aspect of the present invention, this quartz vibrating reed is provided on the underlayer made of one of Ti, Cr and Ni, as in the first aspect of the present invention. And
An intermediate layer formed of a mixed layer of Cu and a conductive metal, and an upper layer provided on the intermediate layer and formed of the conductive metal, wherein at least the upper layer of the extraction electrode portion of the electrode film Is provided with an outermost surface layer made of Al.

After the outermost layer is formed, heat treatment is actively performed to diffuse the material components of the outermost layer into the upper layer below the outermost layer. The components diffuse upward in the thickness direction from the intermediate layer and downward from the outermost layer. In particular, in the third aspect, since the outermost surface layer is formed at the extraction electrode portion connected to the connection electrode to which the power supply electrode serving as the external electrode is connected by solder, the solder has a limited path along the excitation electrode. Al is selectively diffused in addition to Cu.

Thus, an effect exceeding the first aspect is exhibited, and diffusion of the solder component into the electrode film (upper layer) is suppressed.

According to a fourth aspect of the present invention, in the structure of any one of the first to third aspects, the thickness of the underlayer is 50 nm or more and 300 nm or less, and the mixing ratio between Cu and the conductive metal of the intermediate layer is: 30% or more by atomic ratio of Cu, 60
% Or less, the upper layer has a thickness of 200 nm or more and 1800 nm or less, and the total thickness of the upper layer and the intermediate layer is 1000 nm or more and 5000 nm or less.

In the structure of the fourth aspect, the reason why the thickness of the underlayer is not less than 50 nm and not more than 300 nm is that if the thickness is less than 50 nm, the adhesion strength of the electrode film becomes insufficient. If the thickness exceeds 300 nm, the CI value increases to an unacceptable range.

When the atomic ratio of Cu (copper) is less than 30%, the effect of preventing solder diffusion, described later, is reduced or lost. If the atomic ratio of copper exceeds 60%, the frequency changes with the lapse of time after completion of the product.

The total thickness of the intermediate layer and the upper layer is 1
The range of 000 nm or more and 5000 nm or less is that in this range, the CI (crystal impedance) of the product is used.
This is because there is no problem with the value in this range.

Further, if the thickness of only the upper layer is not more than 200 nm, the bonding strength between the connection electrode and the power supply electrode is insufficient, and if it exceeds 1800 nm, the diffusion of copper (Cu) component in the thickness direction is insufficient. Could be.

According to a fifth aspect of the present invention, in any one of the second to fourth aspects, the thickness of the outermost surface layer is 50n.
m or more and 300 nm or less.

According to the structure of the fifth aspect, if the thickness of the outermost surface layer is not more than 50 nm, the effect of reducing the frequency change as described later cannot be obtained. In addition, the thickness of the outermost surface layer is 300 n.
Since this effect is constant at m, the upper limit is set.

According to a sixth aspect of the present invention, in the configuration of any one of the first to fifth aspects, the temperature of the heat treatment is 200 degrees Celsius.
Degrees not less than 300 degrees Celsius and processing time is not less than 2 minutes and 1.5 degrees
It is characterized by being less than an hour.

According to the configuration of the sixth aspect, if the heating is not performed at 200 ° C. or more for 2 minutes or more, the stress in the previous process is relaxed and the diffusion of the necessary Cu component becomes difficult. If the heat treatment is performed for 1.5 hours or more, the bonding strength of the electrode may be insufficient. Further, according to the invention of claim 9, the above object is a crystal device in which a crystal resonator element in a package is housed and sealed,
The quartz vibrating reed includes an excitation electrode to which a drive voltage is applied to a surface, and a connection electrode connected to the excitation electrode via a lead electrode, and applies an external drive voltage to the connection electrode. A power supply electrode for soldering, the electrode film is formed of a first layer made of a conductive metal,
A second layer containing at least Cu, wherein the Cu component of the second layer is diffused with respect to the first layer in the thickness direction of the electrode film. You.

[0045]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a perspective view showing a crystal resonator as an example of a crystal device using a crystal resonator element according to an embodiment of the present invention, FIG. 2 is a schematic plan view thereof, and FIG. 3 is a schematic sectional view thereof. is there.

In these figures, the quartz oscillator 10
Includes a package 12 in which a space 12a is formed, and a plate-shaped crystal vibrating piece 11 which is sealed in the package and is long in one direction.

The quartz-crystal vibrating piece 11 is a plate formed of, for example, quartz in the shape of a strip. On the quartz-crystal vibrating piece 11, an excitation electrode 19 and connection electrodes 13 and 14 are formed in a manufacturing process described later. Have been. The excitation electrode 19 is for applying a drive voltage from the outside to generate a predetermined thickness shear vibration in the quartz crystal based on the piezoelectric action. The excitation electrode 19 and the connection electrode are connected by extraction electrodes 13a and 14a.

The excitation electrode 19 is similarly formed on the back surface of FIG. 1, and the connection electrode 14 is connected to the excitation electrode 19 formed on the front surface side via an extraction electrode 14a. The connection electrode 13 is connected to an excitation electrode (not shown) of the same shape formed on the back surface side via a lead electrode 13a.

The package 12 is formed of, for example, a metal material. Specifically, the package 12
It is made of easy-to-process nickel silver or more preferably Kovar or the like, and is formed as a hollow cylinder having an open front side and a bottom portion 23 at the back in FIG.

The quartz vibrating reed 11 is inserted from the open end 18a of the package 12 into the space 12a. One end of the quartz vibrating reed 11 is provided on the connection electrodes 13 and 14 as a power supply electrode drawn from outside the package. Lead terminal 17,
17, the inner leads 17a, 17a
Are joined using solders 15 and 16, respectively.

Then, the open end 18a of the package 12
Is sealed with a plug 18 fitted therein. The plug 18 is connected to the package 1 as shown in FIGS.
It has a metal ring 18b fitted into the inner periphery of the second open end 18a, and an insulating member 18c made of, for example, a glass material and arranged inside the ring 18b.

The crystal vibrating reed 11 is
Is fixed at one end, and the free end 21 is at the back, so that the crystal resonator element 11 is supported in a cantilever manner. The insulating member 18c of the plug 18
The lead terminals 17 penetrating therethrough are insulated from each other.

As described above, the crystal resonator element of the present invention is applied to various crystal devices such as a crystal oscillator and a crystal oscillator having an integrated circuit added thereto.

Next, a method of manufacturing the above-described crystal resonator element 11 will be described.

FIG. 4 is a flowchart showing a method for manufacturing a crystal resonator element according to the first embodiment of the present invention.

First, an artificial quartz ore obtained by a predetermined crystal growth step is cut to form a quartz wafer. And
The quartz wafer is polished to increase the parallelism between the front and back surfaces of the wafer, and is adjusted to a predetermined thickness. And
The processed crystal wafer is cut to have a chip size for forming a crystal vibrating piece, and the cut end face is polished to obtain a crystal piece 21 (ST10). 1 to 3
The state where the electrode film of the crystal vibrating piece 11 is not formed is the crystal piece 21.

Next, as shown in FIG. 5, an electrode film 25 is formed on the surface (both front and back) of the crystal blank by vapor deposition or the like. The excitation electrode 19 described with reference to FIG.
And connection electrodes 13 and 14 for connecting the excitation electrodes to external electrodes for supplying a drive voltage from the outside (ST11).

FIG. 5 shows the film structure of the electrode film 25. On the crystal blank 11, first, Ti, C
The underlayer 22 is formed from one of r and Ni by vapor deposition or the like. Here, one of Ti, Cr and Ni is used because it has good adhesion to gold or silver as a conductor metal and can avoid an increase in CI value without impairing the function of an intermediate layer described later. Because of nature. Next, a mixed layer 23 of a conductive metal and the above-mentioned copper (Cu) is formed as an intermediate layer
Is formed by vapor deposition or the like. Next, an upper layer 24 serving as an electrode layer is formed on the intermediate layer 23 with a conductive metal, for example, gold (Au) or silver (Ag) by vapor deposition or the like. In this embodiment, silver is selected for the upper layer 24.

Next, after forming the electrode film 25, as shown in FIG. 7, the solders 15, 16 are placed in a state where the power supply electrode (inner lead) 17 a is in contact with the electrode film 25.
(ST12). The solders 15 and 16 may be PbSn as normal solder or SnCu, for example, as lead-free solder. Here, if lead-free solder is used, the influence of lead contamination on the environment does not occur.

Further, after the bonding, a heat treatment is performed (ST).
13). This heat treatment is performed, for example, by placing the electrode film 2 in a thermostat.
This is performed by accommodating the crystal piece 21 on which the crystal 5 is formed.

In this case, the heat treatment relaxes the stress applied to the crystal blank 21 up to the bonding step of ST12, and diffuses the Cu component of the intermediate layer 23 into the upper layer 24 as shown in FIGS. This is performed in order to precipitate as a component 26 on the surface of the upper layer 24.

Thus, in the present embodiment, the underlayer 22
And an intermediate layer 23 is provided thereon, and the Cu component of the intermediate layer 23 is positively diffused in the upper layer direction. 5 and 6
As shown in (2), the electrode layer 24 is deposited up to the upper electrode layer 24, and the electrode layer 24 is treated as a diffusion mixed layer 27 in which a copper (Cu) component 26 is surely present near its surface.

Here, in the present embodiment, the film forming conditions of the electrode film 25 in ST11 are preferably the underlayer 22.
Has a film thickness of 50 nm or more and 300 nm or less, and an atomic ratio of copper is 30% or more and 60% or less with respect to a mixing ratio of copper and a conductive metal such as silver in the intermediate layer 23,
The total thickness of the intermediate layer 22 and the upper layer 24 is 100
The thickness of only the upper layer 24 is set to 200 nm or more and 1800 nm or less.

That is, if the thickness of the underlayer 22 is less than 50 nm, the adhesion strength between the quartz crystal 21 and the intermediate layer 23 is insufficient. If the thickness of the underlayer 22 exceeds 300 nm, CI
This is because the value may increase excessively and exceed the allowable range.

Regarding the mixing ratio of copper and silver in the intermediate layer 23, if the atomic ratio of copper is less than 30%, the effect of preventing solder diffusion described below will be reduced or lost. If the atomic ratio of copper exceeds 60%, the frequency changes with the lapse of time after completion of the product.

The reason why the total film thickness of the intermediate layer 23 and the upper layer 24 is 1000 nm or more and 5000 nm or less is as follows.
This is because there is no problem with the CI (crystal impedance) value of the product in this range.

Further, only the upper layer 24 has a thickness of 200 nm.
Otherwise, the bonding strength between the connection electrode and the power supply electrode becomes insufficient, and if it exceeds 1800 nm, the copper (Cu) component shown in FIG.
May be insufficiently diffused into the upper layer 24.

In the heat treatment in ST13, for example, the temperature is set to 200 degrees Celsius to 300 degrees Celsius, and the processing time is set to 2 minutes to 1.5 hours.

That is, if the heating is not performed at 200 ° C. or more for 2 minutes or more, the stress in the previous process is relaxed and the diffusion of the necessary Cu component becomes difficult.
This is because if the heat treatment is performed at a temperature equal to or higher than 1.5 degrees and the heat treatment is performed for 1.5 hours or more, the bonding strength of the electrodes becomes insufficient.

Next, the mass of the electrode film 25 formed in step ST11 is adjusted, that is, the component of the electrode layer 24 is further evaporated by further vapor deposition, or the electron beam, ion beam or laser A frequency adjustment is performed by irradiating light or the like to finely remove the metal film of the electrode layer 24 to reduce its mass (ST14). That is, the actual vibration frequency is adjusted with respect to the desired frequency of the crystal vibrating reed 11 so as to match the desired vibration performance.

After the frequency adjustment is completed, the crystal resonator element is sealed in the package 12 described in FIG. 1 in a vacuum or nitrogen atmosphere to complete the crystal resonator (ST15). Then, the quartz oscillator is resin-molded (ST16).

The present embodiment is configured as described above. After the power supply electrode 17a is brought into contact with the connection electrode 13 of the electrode film 25 and joined by the solders 15 and 16, the heat treatment of ST13 is performed. By the joining process, the quartz piece 21
And the copper (C) in the intermediate layer 23
The u) component is diffused into the upper layer 24 and further deposited on the surface.

As a result, since there is a copper (Cu) component precipitated up to the surface of the upper layer 24 as an electrode layer, the components of the solders 15 and 16 can be used even in a high temperature environment in a subsequent mounting process or the like. It is difficult to be diffused along the surface of the film 25, and the diffused solder component does not increase the weight of the electrode film 25.

In particular, the diffusion mixed layer 27 and the deposited layer 26 shown in FIG.
Is formed, diffusion of solder at the conventional interface between the underlayer and the upper layer and at the interface between the upper layer and the air layer is suppressed. Then, the diffusion of the solder in the diffusion mixed layer 27 is also suppressed.

Therefore, the weight of the electrode film 25 increases,
It is effectively prevented that the vibration frequency of the crystal vibrating piece 11 shifts below the desired frequency.

Further, since the Cu component diffused from the intermediate layer 23 is a component having a low electric resistance, the diffusion mixed layer 27 shown in FIG. 6 becomes an alloy of silver and copper and has a low resistance value. Therefore, the CI value can be kept low.

FIG. 8 is a flow chart showing a method for manufacturing a crystal resonator element according to a second embodiment of the present invention. FIG.
FIG. 3 is a schematic plan view of a quartz-crystal vibrating piece 30 corresponding to the second embodiment. In this figure, portions denoted by the same reference numerals as those of the quartz-crystal vibrating piece 11 of FIGS. The description of the operation will be omitted.

First, a crystal blank 21 is obtained in the same step as ST10 in FIG. 4 (ST21).

Next, as shown in FIG. 10, an electrode film 36 is formed on the front surface (both front and back surfaces) of the quartz piece by vapor deposition or the like (ST22).

FIG. 10A shows a structure 36 a of at least the region of the excitation electrode 19 in the electrode film 36.
0 (b) shows a structure 36b in a region other than the excitation electrode 19 in the electrode film 36.

In these figures, a base layer 32 made of one of Ti, Cr, and Ni is formed as a base on the quartz piece 21 by vapor deposition or the like. This underlayer 3
2 is the same as the underlayer 22 of the first embodiment.

Next, an intermediate layer 33 which is a mixed layer of a conductive metal, for example, gold (Au) or silver (Ag) and copper (Cu) is formed on the underlayer 32 by vapor deposition or the like.

Next, an upper layer 34 serving as an electrode layer is formed. The upper layer 34 is the same as the upper layer of the first embodiment, and is formed of a conductive metal, for example, gold (Au) or silver (Ag). In this embodiment, silver is selected for the upper layer 34.

Further, after forming the upper layer 34, FIG.
As shown in FIG. 3, the solder 15 and the inner electrode 15a are in contact with the electrode film 36a.
16 (ST23). Solder 15,16
May be PbSn as a normal solder or SnCu as a lead-free solder. Here, if lead-free solder is used, the influence of lead contamination on the environment does not occur.

Further, in this embodiment, as shown in FIG. 9, the outermost surface layer 3
5 is formed (ST24). The outermost layer 34 is formed by vapor deposition or the like with aluminum (Al) selected.

Here, aluminum (Al) is selected as the outermost surface layer 35 because aluminum is formed on a conductive metal and Al is diffused into the conductive metal (Ag or Au) to form a solder. A weight layer is formed on the excitation electrode before the frequency adjustment step in order to increase the mass in advance, which can suppress diffusion into the conductor metal, that the Al component does not increase the CI value, For example, it can serve as an adhesive layer between the conductive metal and the weight layer.

That is, in this case, on the excitation electrode 19, as shown in FIG.
2, an intermediate layer 33, an upper layer 34, and an outermost surface layer 35, and in an electrode portion other than the excitation electrode 19, the electrode film 36 b
Having an underlayer 32, an intermediate layer 33, and an upper layer 34,
The outermost layer 35 is not provided.

Thereafter, a heat treatment is performed (ST25). This heat treatment is performed, for example, by placing the electrode films 36a and 36b in a thermostat.
This is performed by accommodating the crystal piece 21 formed with.

Here, the heat treatment relieves the stress applied to the crystal blank 21 up to the bonding step of ST23,
1 and 12 are performed.

In this embodiment, as shown in FIG. 11A, in the region of the excitation electrode 19, the copper (Cu) component of the intermediate layer 33 is diffused into the upper layer 34. With it,
The aluminum (Al) component of the outermost surface layer 35 diffuses into the upper layer 34, thus forming a diffusion mixed layer 37. Further, the outermost surface layer 35 formed in ST24 exists on the diffusion mixed layer 37.

Further, as shown in FIG. 11B, in a region other than the excitation electrode 19, the copper (Cu) component of the intermediate layer is diffused into the upper layer 34 to form a diffusion mixed layer 37. That is, the copper (Cu) component is diffused into the upper layer 34 to form the diffusion mixed layer 37, and is further deposited on the surface thereof.
The precipitation layer 38 is formed.

Here, as the film forming conditions of the electrode film in ST22, in the present embodiment, preferably, the film thickness of the underlayer 32 is 50 nm or more and 300 nm or less, and copper and a conductive metal such as silver of the intermediate layer 33 are used. The atomic ratio of copper is 30% or more and 60% or less, and the total film thickness of the intermediate layer 32 and the upper layer 34 is 1000
not less than 5000 nm and not more than 5000 nm,
It is set to be not less than 00 nm and not more than 1800 nm.

In the heat treatment in ST25, for example, the temperature is set to 200 ° C. to 300 ° C., and the processing time is set to 2 minutes to 1.5 hours.

These conditions are the same as in the first embodiment.
The reason is also common.

In this embodiment, the outermost surface layer 35 preferably has a thickness of 50 nm or more and 30 nm or more.
0 nm or less.

That is, the thickness of the outermost layer 35 is 50 nm.
Otherwise, the effect of reducing frequency change as described later cannot be obtained. In addition, since this effect is constant when the thickness of the outermost layer 35 is 300 nm, the upper limit is set.

When the heat treatment in ST25 is completed, frequency adjustment (ST26) is performed, the package is sealed with the package 12 (ST27), and a necessary molding process is performed (ST2).
8). These steps correspond to the corresponding ST of the first embodiment.
Same as 14, 15, and 16.

Thus, also in this embodiment, the solder 1
The components 5 and 16 are hardly diffused along the surfaces of the electrode films 36a and 36b even in a high temperature environment in a subsequent mounting process or the like, and the diffused solder components do not increase the weight of the electrode films.

Particularly, in the region of the excitation electrode 19, as shown in FIG. 11, the outermost surface layer 34 and the diffusion mixed layer 37 are formed, and in the other regions, the diffusion mixed layer 37 and the deposited layer 3 are formed.
Due to the formation of 8, the diffusion of solder at the conventional boundary between the upper layer and the air layer and the boundary between the upper layer and the base layer can be suppressed.

Therefore, it is possible to effectively prevent the oscillation frequency of the quartz-crystal vibrating reed 11 from being lower than a desired frequency due to an increase in the weight of the electrode films 36a and 36b.

In this case, since the Cu component diffused from the intermediate layer 33 and the outermost surface layer 35 is a component having a low electric resistance, the diffusion mixed layer 37 becomes an alloy of silver and copper, Value is low, so that the CI value can be kept low.

In the present embodiment, in particular, in the case where a gold or silver weight layer is newly provided on the outermost surface layer 34 by evaporation or the like by the weight increasing method in ST26, the gold The adhesion of the weight layer is improved as compared with the case where a weight layer is added to the electrode surface of silver or silver. Therefore, it is possible to prevent the added weight layer from peeling off when the product is used. Further, when the frequency adjustment method using the mass reduction processing is used, the rate of change in frequency can be reduced due to the presence of Al, which is suitable for precise frequency adjustment.

FIG. 13 is a flowchart showing a method of manufacturing a quartz-crystal vibrating piece according to the third embodiment of the present invention. FIG. 14 is a schematic plan view of a quartz-crystal vibrating piece 40 corresponding to the third embodiment. In this figure, the portions denoted by the same reference numerals as those of the quartz-crystal vibrating piece 11 of FIGS. , Overlapping description will be omitted.

In FIG. 13, the steps of ST31, ST32, ST33 are the same as the steps described in ST21, ST22, ST23 of FIG.

In this embodiment, after the bonding step ST23, as shown in FIG. 15, an electrode film is formed on the front and back surfaces of the crystal blank 21. Here, FIG. 15A shows the film structure of the portion of the extraction electrode of the crystal vibrating piece 40 of FIG. 14, and FIG. 15B shows the film structure of at least the region of the excitation electrode 19. I have.

In each of these film structures, the portions denoted by the same reference numerals as those in the second embodiment have the same layer structure.
Duplicate description will be omitted.

In ST34, the outermost surface layer 44 is formed on the upper layer 34 of the region of the extraction electrode 14a shown in FIG. 14 (the same applies to the back extraction electrode 13a). In this case, the outermost surface layer 44 is formed of aluminum similarly to the outermost surface layer 35 of the second embodiment.

Next, heat treatment is performed in ST35. The conditions for this heat treatment are the same as those in ST25 of the second embodiment.

FIG. 15 shows the film structure after the heat treatment in ST35.
(C) and FIG. 15 (d). In this case, FIG.
14 shows the film structure of the extraction electrode portion of the crystal resonator element 40 of FIG. 14 after the heat treatment, and FIG. 15D shows the film structure of at least the region of the excitation electrode 19.

As can be seen from a comparison between FIG. 15A and FIG. 15C, on the extraction electrode 14a (13a),
The copper (Cu) component of the intermediate layer 33 diffuses upward with respect to the upper layer 34 in the film thickness direction. At the same time, the aluminum (Al) component of the outermost layer 44 diffuses downward with respect to the upper layer 34 in the film thickness direction, and thus the diffusion mixed layer 3
7 is formed.

Further, as can be seen from a comparison between FIG. 15B and FIG. 15D, in the region of the excitation electrode 19, the copper (Cu) component of the intermediate layer 33 is diffused into the upper layer 34 in the film thickness direction. , A diffusion mixed layer 37 is formed. That is, in the upper layer 34, the copper (Cu) component is diffused to form the diffusion mixed layer 37, and the component is deposited on the surface to form the deposited layer 38.

Next, frequency adjustment is performed (ST3).
6). This step is particularly important. In the present embodiment, the frequency adjustment is performed by irradiating the diffusion mixing layer 37 in the region of the excitation electrode 19 with, for example, an electron beam, an ion beam, or a laser beam. A frequency adjustment is performed to delicately remove the metal film of the layer 37 to reduce its mass.

This is for the following reason.

In this embodiment, the extraction electrode 14a
The outermost surface layer 44 is formed on the surface of (13a), and this region is formed in each of the upper and lower directions from the outermost surface layer 44 and the intermediate layer 33 toward the upper layer 34, particularly in the film thickness direction. Copper (Cu) and aluminum (Al) components are diffused, and diffusion of solder components is prevented. In particular, since the solder is applied to the connection electrodes 13 and 14 in FIG. 14, if the location of the lead electrode 14a (13a) is selectively treated, most of the solder diffusion can be effectively prevented. Functions and effects similar to those of the other embodiments are exhibited.

On the other hand, since the outermost surface layer 44 is not formed in the region of the excitation electrode 19, a metal having a high removal efficiency, such as an alloy of silver and copper, of the diffusion mixed layer 37 in this region is selectively removed. be able to. That is, since there is no tough oxide film (aluminum oxide) made of aluminum in the region of the excitation electrode 19, the frequency adjustment of the mass reduction method can be performed in a short time.

Thus, by shortening the frequency adjustment time, the temperature does not increase significantly during the frequency adjustment, and does not cause an excessive frequency change in relation to the temperature decrease after the end of the frequency adjustment. Can be effectively prevented from greatly changing later.

When the frequency adjustment is completed, the crystal resonator element is sealed in the package 12 described in FIG. 1 in a vacuum or nitrogen atmosphere to complete the crystal resonator (ST37). Then, this crystal resonator is resin-molded (ST38).

FIG. 16 is a table summarizing the samples in which the quartz-crystal vibrating pieces were manufactured by several manufacturing methods.
In this table, Sample 1 and Sample 2 are comparative examples manufactured by a conventional manufacturing method different from the present invention,
All the other samples were obtained by applying each embodiment of the present invention. This table shows the details of each sample under the above-described conditions such as each underlayer and intermediate layer.
Up to this, the manufacturing method of the first embodiment is applied and the conditions are variously changed. Sample 8 is based on the second embodiment, and sample 9 is based on the third embodiment.

FIG. 17 shows, for each sample of FIG.
The results of testing its performance are shown.

With respect to the aging characteristics, which were tested at 125 degrees Celsius for 1000 hours after the production, Samples 3 to 9 of the present invention showed good results with a frequency change of -5 ppm or less and Samples 14 and 15 of -2 ppm or less. , And CI values were as good as 5Ω or less. The invention is not limited to the embodiments described above. Each configuration of each of the above-described embodiments can be omitted or arbitrarily combined as appropriate.

Further, the quartz-crystal vibrating reed and the method of manufacturing the same according to the present invention can be applied not only to the quartz-crystal vibrator and the crystal oscillator but also to any quartz-crystal device using the quartz-crystal vibrating reed.

[0123]

As described above, according to the present invention, a crystal vibrating reed can be prevented from deteriorating vibration characteristics by sufficiently diffusing and mixing a component capable of preventing the diffusion of a solder component into an electrode film. And a crystal device using a crystal vibrating piece having such characteristics can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view showing an example of a crystal resonator as a crystal device according to an embodiment of the present invention.

FIG. 2 is a schematic horizontal sectional view of the crystal unit shown in FIG.

FIG. 3 is a schematic vertical sectional view of the crystal unit shown in FIG. 1;

FIG. 4 is a flowchart for explaining a first embodiment of a method for manufacturing a crystal resonator element according to the present invention.

FIG. 5 is a schematic sectional view showing a film structure of an electrode film according to the manufacturing method of FIG. 4;

FIG. 6 is a schematic cross-sectional view showing a film structure of an electrode film after heat treatment by the manufacturing method of FIG. 4;

FIG. 7 is a schematic cross-sectional view showing the principle of diffusing a high melting point metal component of an electrode film by the manufacturing method of FIG.

FIG. 8 is a flowchart for explaining a second embodiment of the method for manufacturing a crystal resonator element according to the present invention.

FIG. 9 is a schematic plan view showing a crystal resonator element manufactured by the manufacturing method of FIG.

10 shows a film structure of an electrode film according to the manufacturing method of FIG. 8, and (a) a schematic cross-sectional view of a film structure in a region of an excitation electrode;
(B) Schematic sectional view of the film structure in a region other than the excitation electrode.

11 shows a film structure of the electrode film after the heat treatment by the manufacturing method of FIG. 8; FIG. 11 (a) is a schematic cross-sectional view of a film structure in a region of an excitation electrode; FIG.

FIG. 12 is a schematic cross-sectional view showing the principle of diffusion of copper and Al components of an electrode film by the manufacturing method of FIG.

FIG. 13 is a flowchart for explaining a third embodiment of the method for manufacturing a crystal resonator element according to the present invention.

FIG. 14 is a schematic plan view showing a crystal resonator element manufactured by the manufacturing method of FIG. 13;

15A is a schematic cross-sectional view of a film structure in a region of an extraction electrode of an electrode film by the manufacturing method of FIG. 13, FIG. 15B is a schematic cross-sectional view of a film structure of a region of an excitation electrode thereof, and FIG. FIG. 3D is a schematic cross-sectional view of a film structure in a region of a lead electrode of an electrode film after heat treatment by a manufacturing method, and FIG.

FIG. 16 is a table showing manufacturing conditions of a sample using the manufacturing method of each embodiment of the present invention and manufacturing conditions of a sample of a comparative example.

FIG. 17 is a table comparing the performance of each sample of FIG. 16;

FIG. 18 is a flowchart for explaining a conventional method for manufacturing a crystal resonator element.

FIG. 19 shows a structure of an electrode film of a conventional quartz-crystal vibrating piece.
(A) Schematic sectional view showing a film structure at the time of manufacture, (b) Schematic sectional view showing a change in an electrode film structure due to thermal influence after manufacture.

FIG. 20 is a graph showing a state of a frequency change due to a thermal influence after manufacturing a conventional crystal resonator element.

FIG. 21 is a schematic cross-sectional view showing a state of diffusion of a solder component due to a thermal effect after manufacturing a conventional crystal resonator element.

[Explanation of symbols]

 REFERENCE SIGNS LIST 10 crystal resonator 11 crystal resonator element 12 package 13 connection electrode 13 a extraction electrode 14 connection electrode 14 a extraction electrode 15 solder 16 solder 17 a power supply electrode 19 excitation electrode 21 crystal piece 22 base layer 23 intermediate layer 24 upper layer (electrode layer) 25 electrode film

Continued on front page F term (reference) 5J108 BB02 CC04 DD02 EE02 EE11 FF03 FF04 FF05 FF07 FF08 FF10 FF15 GG06 KK02 KK05 MM14 NB02 NB03

Claims (7)

[Claims] An excitation electrode to which a driving voltage is applied to the surface of a crystal blank, and a connection electrode connected to the excitation electrode via an extraction electrode, wherein an external driving voltage is applied to the connection electrode. A method for manufacturing a crystal vibrating piece to which a power supply electrode for applying a voltage is applied, wherein the crystal piece is formed from a crystal wafer obtained by cutting a crystal block, and Ti, Cr, A base layer made of one of Ni, an intermediate layer provided on the base layer, the mixed layer of Cu and the conductive metal, and an upper layer provided on the intermediate layer and made of the conductive metal; Forming an electrode film having the following structure. The power supply electrode is brought into contact with a connection electrode of the electrode film and joined by soldering. Then, heat treatment is performed to relieve the stress applied to the crystal blank until the joining step. Together with the material components of the intermediate layer Manufacturing a quartz-crystal vibrating reed by diffusing into the upper layer, depositing on the surface of the upper layer, and further adjusting the frequency by performing a mass increase or mass reduction process on the surface of the electrode film. Method. 2. An excitation electrode for applying a drive voltage to the surface of a crystal blank, and a connection electrode connected to the excitation electrode via an extraction electrode, and an external drive voltage is applied to the connection electrode. A method for manufacturing a crystal vibrating piece to which a power supply electrode for applying a voltage is applied, wherein the crystal piece is formed from a crystal wafer obtained by cutting a crystal block, and Ti, Cr, A base layer made of one of Ni, an intermediate layer provided on the base layer, the mixed layer of Cu and the conductive metal, and an upper layer provided on the intermediate layer and made of the conductive metal; Is formed, and the power supply electrode is brought into contact with the connection electrode of the electrode film and joined by soldering. Further, at least on the excitation electrode, an outermost surface layer of Al is formed, and then heat treatment is performed. By this, up to the joining process Relaxing the stress applied to the crystal blank, and diffusing the material component of the intermediate layer into the upper layer and depositing it on the surface of the upper layer, and diffusing Al of the outermost layer into the upper layer, A method of manufacturing a quartz vibrating piece, wherein the frequency is adjusted by performing a mass increase or mass reduction process on the surface of the electrode film. 3. An excitation electrode to which a drive voltage is applied to the surface of a crystal blank, and a connection electrode connected to the excitation electrode via an extraction electrode, and an external drive voltage is applied to the connection electrode. A method for manufacturing a crystal vibrating piece to which a power supply electrode for applying a voltage is applied, wherein the crystal piece is formed from a crystal wafer obtained by cutting a crystal block, and Ti, Cr, A base layer made of one of Ni, an intermediate layer provided on the base layer, the mixed layer of Cu and the conductive metal, and an upper layer provided on the intermediate layer and made of the conductive metal; Is formed, and the power supply electrode is brought into contact with the connection electrode of the electrode film and joined by soldering. Further, an outermost surface layer of Al is formed on at least the extraction electrode, and then heat treatment is performed. By doing so, The stress applied to the crystal blank is alleviated, and the material component of the intermediate layer is diffused into the upper layer to precipitate on the surface of the upper layer, and the Al of the outermost surface layer is diffused into the upper layer. A method for producing a quartz-crystal vibrating piece, wherein the frequency is adjusted by performing a mass increase or mass reduction process on the surface of the electrode film. 4. The method according to claim 1, wherein the thickness of the underlayer is 50 nm or more, and
0 nm or less, the mixing ratio of Cu and the conductive metal of the intermediate layer is 30% or more and 60% or less in atomic ratio of Cu, and the film thickness of the upper layer is 200 nm or more and 1800 nm or less; The combined film thickness of the intermediate layer is 1000 nm or more,
4. The method for manufacturing a quartz vibrating reed according to claim 1, wherein the thickness is 5000 nm or less. 5. The method according to claim 1, wherein the outermost surface layer has a thickness of 50 nm or more.
The method according to claim 2, wherein the thickness is 300 nm or less. 6. The method according to claim 1, wherein the temperature of the heat treatment is not less than 200 degrees Celsius and not more than 300 degrees Celsius, and the treatment time is not less than 2 minutes and not more than 1.5 hours. Manufacturing method of crystal vibrating piece. 7. A crystal device in which a crystal vibrating piece in a package is housed and sealed, wherein the crystal vibrating piece includes an excitation electrode to which a drive voltage is applied to a surface, and an excitation electrode and a lead electrode. A power supply electrode for applying an external drive voltage to the connection electrode by soldering, and the electrode film is formed of a first layer made of a conductive metal. And a second layer containing at least Cu, wherein a Cu component of the second layer is diffused in the thickness direction of the electrode film with respect to the first layer. , Crystal devices.