JPH05160659A - Production of piezoelectric oscillating element - Google Patents

Abstract

PURPOSE:To improve the performance with respect to the production of an energy two-dimensional confinement type perpendicular slip oscillating element. CONSTITUTION:Driving electrodes 3, 4 are formed on the central part of a piezoelectric substrate 2, and a part 13 of the piezoelectric substrate 2 on the side of driving electrodes 3, 4 is made amorphous. This constitution is characterized by forming driving electrodes 3, 4 on the central part of the piezoelectric substrate 2 and giving a part 13 of the piezoelectric substrate 2, which is placed on the side of driving electrodes 3, 4, with the processing strain remaining treatment. The piezoelectric substrate 2 is so cut out that chippings 14 are formed in the peripheral edge part, and driving electrodes 3, 4 are formed on the central part of the piezoelectric substrate 2. Many chippings 14 are formed in the outer edge part of the piezoelectric substrate 2 whose central part has the driving electrodes 3 and 4 formed thereon.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an energy two-dimensional confinement type thickness shear vibration element, and more particularly to a method for improving the oscillation frequency characteristic when used in a voltage controlled oscillator.

[0002]

2. Description of the Related Art Conventionally, an energy two-dimensional confinement type thickness-shear vibrating element (hereinafter abbreviated as vibrating element) is formed by cutting out a piezoelectric substrate having a square or circular shape from a single crystal of lithium tantalate or lithium niobate. A drive electrode at the center of the substrate and a lead extending from the drive electrode are formed.

FIG. 7 is a plan view (a) and a side view (b) showing a conventional vibrating element. The piezoelectric substrate 2 of the vibrating element 1 is cut out from a single crystal of lithium tantalate or lithium niobate. The drive electrode 3 located at the center of the substrate 2 and the lead 5 extending rightward from the electrode 3 are pattern-formed on the front surface of the substrate 2, and the drive electrode 3 is opposed to the back surface of the substrate 2. The drive electrode 4 and the lead 6 extending leftward from the electrode are patterned.

In such a vibrating element, for example, a terminal electrode is formed on a package substrate, and the terminal electrode and the outer end portion of the lead are connected by a conductive adhesive or the like.

[0005]

FIG. 8 is a diagram showing the admittance characteristic of the resonator element manufactured by the conventional method, and FIG. 9 is a diagram showing the relationship between the control voltage and the oscillation frequency of the resonator element manufactured by the conventional method.

In FIG. 8, the vertical axis is the attenuation amount, the horizontal axis is the frequency, and the admittance characteristic A of the vibrating element having an oscillation range of 18.125 MHz ± 0.2 MHz has many spurious s due to the harmonics of the external vibration. Occurs, especially in the oscillation range (17.
Spurious s within 925MHz to 18.325MHz is harmful.

In FIG. 9, the ordinate represents the oscillation frequency and the abscissa represents the control voltage. When an oscillating element having spurious s within the oscillation range as shown in FIG. 8 is used as, for example, a voltage controlled oscillator, the oscillation frequency and the control are controlled. In the voltage correlation characteristic B, a jump j occurs at the position of the control voltage -1.8V, resulting in poor linearity.

As a conventional technique for eliminating spurious s, there is a method of applying a sound absorbing material (resin) to the piezoelectric substrate 2. However, in such a conventional method, since the sound absorbing material dropped on the piezoelectric substrate 2 spreads before and during the curing, it is difficult to control the application area and the application amount, and when a part of the sound absorbing material covers the drive electrode, the resonance resistance is reduced. Has the drawback that it suddenly deteriorates and becomes unusable.

[0009]

FIG. 1 is a conceptual diagram of the method of the present invention. In FIG. 1A, the vibration element 11 is the piezoelectric substrate 2
Are cut out from a single crystal of lithium tantalate or lithium niobate, and drive electrodes 3, 4 and leads 5, 6 are patterned on the front surface and the back surface of the piezoelectric substrate 2, and at least one of the front surface and the back surface of the piezoelectric substrate 2 is formed. Is a part apart from the drive electrodes 3 or 4 (upper side part and lower side part)
13 is made amorphous by laser light irradiation or the like, and internal strain is left by lapping.

In FIG. 1B, the vibration element 12 is cut out from a single crystal of lithium tantalate or lithium niobate, and the drive electrodes 3 and 4 are formed in the central portion of the piezoelectric substrate (2, 8). A large number of chippings 14 are formed.

[0011]

According to the above means, the amorphization of the piezoelectric substrate, the internal strain residual treatment, or the chipping is formed so that the contour vibration that causes the spurious is attenuated and diffusely reflected. Spurious is suppressed and the characteristics of the piezoelectric vibrator are improved.

[0012]

FIG. 2 is an explanatory view of the main manufacturing steps of a vibration element according to the first embodiment of the present invention, FIG. 3 is an admittance characteristic diagram of the vibration element manufactured by the method shown in FIG. 2, and FIG. FIG. 5 is a diagram showing a relationship between a control voltage and an oscillation frequency when a vibrating element manufactured by the method shown is used as a voltage controlled oscillator, FIG. 5 is an explanatory view of main manufacturing steps of the vibrating element according to the second embodiment of the present invention, FIG. 6 is an explanatory view of main manufacturing steps of the vibration element according to the third embodiment of the present invention.

In FIG. 2 (a), a piezoelectric substrate (wafer in mass production) 2 is cut out from a single crystal of lithium tantalate or lithium niobate, and then the surface of the piezoelectric substrate 2 as shown in FIG. 2 (b). The electrode forming film 7 is applied to the back surface and the back surface.

Then, unnecessary portions of the electrode forming film 7 are removed and, as shown in FIG. 2C, the drive electrodes 3, 4 and the leads 5,
6 (Many electrodes and leads on one wafer for mass production)
After forming the pattern, the drive electrode 3 or the drive electrode 4
Alternatively, as shown in FIG. 2D, the upper and lower side portions (amorphization regions) 13 of the drive electrodes 3 and 4 are irradiated with a large number of amorphization spots 15, for example, laser light (heat ray) spots about tens of times. Amorphized spot 15 formed by
In terms of mass production, each amorphized region of the wafer before division 13
An amorphized spot 15 is formed on the surface, and the vibration element _1-1 is completed.

A shaker which has been subjected to such an amorphization treatment
Moving element 1_-1Admittance characteristics A _-1Is the amount of attenuation on the vertical axis
And the horizontal axis is the frequency, and the curve is as shown in Fig. 3,
It occurred before the amorphization process as shown by the broken line in the figure.
Spurious s disappears.

Further, when the vibrating element 1 _-1 is used as a voltage controlled oscillator, the correlation characteristic B _-1 between the oscillation frequency and the control voltage is shown in FIG. 4 with the ordinate indicating the oscillation frequency and the abscissa indicating the control voltage.
The jump j (see FIG. 9) generated before the amorphization process disappears and the linearity (linearity) is improved.

In FIG. 5A, a piezoelectric substrate (wafer in mass production) 2 is cut out from a single crystal of lithium tantalate or lithium niobate, and then the surface of the piezoelectric substrate 2 is cut as shown in FIG. 5B. The electrode forming film 7 is applied to the back surface and the back surface.

Then, the unnecessary portions of the electrode forming film 7 are removed and, as shown in FIG. 5C, the drive electrodes 3, 4 and the leads 5,
6 (Many electrodes and leads on one wafer for mass production)
After forming the pattern, the drive electrode 3 or the drive electrode 4
Alternatively, as shown in FIG. 5D, in the upper and lower side portions (working strain residual area) 13 of the drive electrodes 3 and 4, a large number of fine scratches 16 are formed by a processing strain residual treatment, for example, lapping or polishing paper or a metal cutter. Paste, vibrating element 1 _-2 completed.

By attaching such fine flaws 16
Resonance element 1 with residual processing strain _-2Admittant
The vibration characteristic is that the vibrating element 1 that has been amorphized_-1of
Similar to that (Fig. 3), sprinkles before processing strain residual treatment
Asbestos is eliminated and the vibration element 1_-2Voltage controlled oscillator
When used as, the correlation characteristics between oscillation frequency and control voltage
The vibrating element 1 that has undergone amorphization treatment_-1That of
Similar to (Fig. 4), jump j (see Fig. 9) disappears and the line
Shape is improved.

In FIG. 6 (a), a wafer (piezoelectric substrate) 8 is cut out from a single crystal of lithium tantalate or lithium niobate, and an electrode forming film (7) is adhered to the front and back surfaces of the wafer 8. As shown in FIG. 6B, unnecessary portions of the electrode formation film are removed and a large number of drive electrodes 3 (and 4 not shown) and leads 5 (and 6 not shown) are patterned.

Thereafter, when the wafer 8 is diced (cut) along the alternate long and short dash line 9 shown in FIG. 6C by rotating at a slower speed or faster than the conventional method, as shown in FIG. A vibrating element 12 having a large number of chippings 14 on the peripheral edge thereof is completed.

[0022] Similar to the admittance characteristics of the vibrating element 12 subjected to such chipping process, that of the vibrating elements 1 _-1 subjected to amorphization process (FIG. 3), the correct linear
The spurious generated by cutting into (or the curve) is eliminated, and when the vibrating element 12 is used as a voltage controlled oscillator, the correlation characteristic between the oscillation frequency and the control voltage is also that of the vibrating element 1 _-1 which has been subjected to the amorphization process. Similar to (FIG. 4), the jump j (see FIG. 9) disappears and the linearity is improved.

[0023]

As described above, according to the method of the present invention, spurious in the admittance characteristic is eliminated,
When used as an oscillator, the stability with respect to temperature, load capacitance, etc. is improved, and when used as a voltage controlled oscillator, the linearity of the correlation characteristic between the oscillation frequency and the control voltage is improved.

[Brief description of drawings]

FIG. 1 is a conceptual diagram of the method of the present invention.

FIG. 2 is an explanatory diagram of main manufacturing steps of the resonator element according to the first embodiment of the present invention.

3 is an admittance characteristic diagram of the resonator element manufactured by the method shown in FIG.

FIG. 4 is a correlation diagram between a control voltage and an oscillation frequency in a voltage controlled oscillator using the vibration element manufactured by the method shown in FIG.

FIG. 5 is an explanatory diagram of main manufacturing steps of the resonator element according to the second embodiment of the present invention.

FIG. 6 is an explanatory diagram of main manufacturing steps of the resonator element according to the third embodiment of the present invention.

FIG. 7 is an explanatory diagram of a conventional vibrating element.

FIG. 8 is an admittance characteristic diagram of the resonator element manufactured by the conventional method.

FIG. 9 is a correlation diagram between a control voltage and an oscillation frequency in a voltage controlled oscillator using a vibration element manufactured by a conventional method.

[Explanation of symbols]

2 is a piezoelectric substrate (wafer) 3, 4 is a drive electrode 5, 6 is a lead extending from the drive electrode 8 is a wafer (piezoelectric substrate) 11, 11 _-1, 11 _-2 , 12 is an oscillating element 13 is amorphized Or processing strain residual processing area 14 is chipped

Claims (5)

[Claims] 1. A two-dimensional energy confinement type thickness-shear vibrating element, in which a drive electrode (3, 4) is formed at the center of a piezoelectric substrate (2) cut from a single crystal of lithium tantalate or lithium niobate. A method for manufacturing a piezoelectric vibrating element, characterized in that a part (13) of the piezoelectric substrate (2) located on the side of the drive electrode (3, 4) is made amorphous. 2. The method for manufacturing a piezoelectric vibrating element according to claim 1, wherein the amorphization according to claim 1 is laser light irradiation. 3. A two-dimensional energy confinement type thickness-shear vibration element, in which a drive electrode (3, 4) is formed at the center of a piezoelectric substrate (2) cut out from a single crystal of lithium tantalate or lithium niobate. A method for manufacturing a piezoelectric vibrating element, characterized in that a part (13) of the piezoelectric substrate (2) located on the side of the drive electrode (3, 4) is subjected to internal strain residual treatment. 4. The method for manufacturing a piezoelectric vibration element according to claim 3, wherein the processing strain residual treatment according to claim 3 is a lapping treatment. 5. A two-dimensional energy confinement type thickness-shear vibrating element, which is a piezoelectric substrate (2,8) having a drive electrode (3,4) formed at the center thereof, which is cut out from a single crystal of lithium tantalate or lithium niobate. A method for manufacturing a piezoelectric vibrating element, characterized in that a large number of chippings (14) are formed on the outer edge of