JPH10284968A - Manufacture of crystal vibrator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve adhesive property to the base electrode film of a silver vapor depositing film, to simplify production process and, at the same time, to improve quality by utilizing a plasma so as to scrape a crystal vibrator chip electrode surface and adjusting a frequency and a temp. coefficient. SOLUTION: The specified position of the electrode film is scraped by the sputtering actuation of a plasma ion so as to adjust an oscillation frequency and the temp. coefficient. Sputtering speed and ion irradiating energy are controlled by the electric condition of a plasma source and the adjustment of vacuum pressure and a plasma generating gas flowrate and plasma sputtering is drastically superior in control property. Thus, adhesive property in the film is improved and an organic matter, etc., on the surface of the electrode film is removed by a sputtering actuation so as to be discharged. Besides, the frequency is not shifted in accordance with adjustment quantity. It is adequate that two holes for adjusting the temp. coefficient are hidden by a mask, etc., in frequency adjustment process by the complete linearity of the in-vacuum ion and mask aligning is facilitated compared with a vapor depositing method.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for adjusting a frequency and a temperature coefficient of a GT-cut quartz resonator.

[0002]

2. Description of the Related Art GT-cut quartz oscillators have an oscillation frequency of 2 to 3 MHz, and have a very small change in oscillation frequency due to temperature. In addition to office equipment such as facsimile machines and computers, portable equipment. Is often used. Hereinafter, a manufacturing process of the GT-cut crystal resonator will be briefly described.

FIG. 5 shows an example of a pedestal on which a GT-cut quartz oscillator and a quartz oscillator chip on which an electrode film is formed before a vacuum sealing step are mounted. This vibrator is different from a simple rectangle like an AT-cut vibrator and has a complicated chip shape. Therefore, the vibrator is formed from a quartz crystal wafer by photolithography. First, chromium, gold, or the like, which is an electrode material, is formed in a predetermined thickness on the entire surface of the cleaned wafer surface, and then etched into a crystal shape and an electrode shape. After separation into individual chips, the chips are mounted on a pedestal that has been soldered to leads in advance with an adhesive. The pedestal is an insulating substrate having a linear expansion coefficient close to that of the vibrator, and has six small holes for adjustment. The two holes at the center are holes for vapor deposition for adjusting the temperature coefficient, and the four holes at the periphery are holes for adjusting the frequency. Cure adhesive (stabilization process)
After that, a small amount of silver is deposited by a vapor deposition method through a hole of the pedestal at a predetermined position on the electrode surface to adjust the frequency and the temperature coefficient. The GT-cut quartz resonator has one feature in that the position for adjusting the frequency and the position for adjusting the temperature coefficient are different from each other. After the frequency adjustment, vacuum heating baking is performed, and then vacuum sealing is performed. After aging, electrical characteristics are measured and sorting is performed.

[0004]

However, such conventional frequency adjustment methods and temperature coefficient adjustment methods have the following problems. First, the adhesion of the deposited silver film to the underlying electrode film becomes a problem. This is presumed to be due to contamination of the electrode surface with organic substances and the like. For example, there are cases where the elapsed time from chip formation to before frequency adjustment or temperature coefficient adjustment is long, or when exposed to a high humidity atmosphere. Alternatively, volatile organic substances generated from jigs and adhesives during the curing step or vacuum heating baking, oil contamination of the vacuum exhaust system, and the like may be caused. If the adhesion is inferior, naturally, the deposited silver is peeled off from the electrode surface, and the oscillation frequency and the temperature characteristic are largely shifted.

[0005] Then, there is a problem that vacuum heating baking is always required after silver deposition. In the case of depositing silver, the oscillator is not particularly heated because it is performed while monitoring the oscillation frequency of the oscillator at room temperature. Therefore, due to lack of surface migration of the deposited silver particles arriving at the electrode surface,
The formed silver thin film is a very coarse film and is chemically unstable. Therefore, vacuum baking is indispensable to obtain a dense and stable film. The necessity of this baking is one of the causes of lengthening the manufacturing process and contaminating the electrode surface with organic substances.

Another problem is that the amount of frequency shift after vacuum heating and baking varies depending on the amount of silver deposited. The true cause of the frequency shift is currently unknown,
Oxidation and diffusion phenomena of silver and the like are estimated as the factors. Further, after the temperature coefficient adjustment and before the frequency adjustment, a step of closing the hole of the pedestal with an adhesive or the like and curing is required. If two holes in the center row for adjusting the temperature coefficient are open during frequency adjustment, silver is also deposited from this hole, and the temperature coefficient set in a predetermined range changes. Therefore, these two holes need to be closed after the temperature coefficient adjustment. This step is unnecessary if the evaporation holes can be concealed by a mask when performing the evaporation method, but mechanical positioning of the mask is difficult due to the small pedestal size. This is because in vapor deposition, a precise alignment is required because a wraparound phenomenon of the vapor deposition material occurs.

As described above, since the number of times of baking and the necessity of curing the adhesive are required as compared with the manufacturing process of the AT-cut quartz resonator, the process becomes longer, and the influence of particles and humidity in the process is increased. And the manufacturing yield tends to vary widely. In addition to the adjustment by the vapor deposition method described above, there is also a method of performing adjustment by taking a part of the electrode film in principle. For example, in a tuning fork type crystal resonator, it is widely used as a “laser trimming technique”. The laser trimming method is a method of adjusting the oscillation frequency by instantaneously evaporating an electrode material in a minute area at a spot position irradiated with a laser. However, this method evaporates both the front and back electrode films, resulting in the same state as a hole in the electrode film, and is not applicable to the present vibrator.

[0008]

In order to solve the above-mentioned problems, plasma is generated, and a specific position of an electrode film is cut by sputtering of ions in the plasma to adjust an oscillation frequency and a temperature coefficient. Sputtering by plasma is a method in which the electrode film on one side is shaved from the outermost surface to a predetermined depth, but the electrical conditions (anode voltage,
The sputtering speed and the ion irradiation energy can be controlled by adjusting the emitter current, the extraction voltage, etc.), the vacuum pressure, and the gas flow rate for plasma generation. That is, the controllability is extremely excellent. According to this method, the problem of film adhesion does not arise from the principle. Organic substances and the like on the surface of the electrode film are easily removed and exhausted by the sputtering action. Further, the frequency does not shift according to the adjustment amount. In addition, vacuum heating baking immediately after adjustment is not always necessary, and may be performed after press-fitting. Also, from the linearity of ions in vacuum, the two holes for adjusting the temperature coefficient may be covered with a mask or the like in the frequency adjustment step, and the alignment of the mask is easier than in the vapor deposition method.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described with reference to the drawings. (Embodiment 1) FIG. 1 shows an example of frequency adjustment. The oscillation frequency is 2.4 MHz. The hole for adjusting the temperature coefficient is hidden by the mask. Argon was used as a plasma generation gas. The flow rate is 4.8 sccm and the process pressure is 2 × 10 ^-4 Torr. According to the figure, the frequency does not change for about 2 seconds after the start of ion irradiation, but thereafter, the processing amount (frequency change amount) is proportional to the ion irradiation time.
Under these conditions, the processing rate was about 90 Hz / sec. This processing rate is almost equal to that of the vapor deposition method. FIG.
Shows an example of temperature coefficient adjustment. The holes for frequency adjustment are covered with a mask. The amount of change in the temperature coefficient depends on the processing time. Thus, adjustment by ion irradiation is possible through the hole of the pedestal.

(Embodiment 2) An example of a manufacturing apparatus capable of actually performing the present invention will be described. FIG. 3 shows an example of an apparatus for continuously performing frequency adjustment and temperature coefficient adjustment. In the apparatus shown in FIG. 3, reference numeral 7 denotes a processing chamber, 8 denotes a load chamber, and 9 denotes an unload chamber. These three vacuum chambers are evacuated (1
Reference numerals 0, 11, and 12 denote vacuum evacuation systems of a processing chamber, a load chamber, and an unload chamber, respectively, and a gas supply system (13,
14 is for generating plasma, for example, using argon.
5, 16, and 17 are used for substitution, for example, nitrogen is used). The processing chamber includes two sets of plasma sources 18 and 19, shutters 20 and 21, masks 22 and 23, transfer system 24, and jigs 25 and 26 for measuring frequency and resonance resistance.
27 is a network analyzer that measures the oscillation frequency and the resonance resistance value of the vibrator. The work enters from the load chamber 8, moves to the processing chamber 7 by the transfer system 24,
After adjusting the temperature coefficient to a predetermined range by (for temperature coefficient adjustment), the frequency is continuously adjusted by the plasma source 19 (for frequency adjustment) on the right side. The shutters 20, 21 perform open / close operations to determine the start and end of ion irradiation on the work. Therefore, the shutter needs to operate at high speed. The work whose adjustment has been completed is taken out of the unloading chamber 9.

The data shown in FIGS. 1 and 2 are obtained by performing experiments using the same apparatus as that shown in FIG. Also, if the unloading chamber 9 of the apparatus shown in FIG. 3 and the vacuum sealing process of the subsequent process are connected by a gate valve and sealed without breaking the vacuum after adjusting the frequency, the vibrator may be affected by moisture and particles in the atmosphere. Can be avoided as much as possible, and a vibrator with higher quality can be manufactured.

(Embodiment 3) Another application example using the present invention will be described. FIG. 4 shows an example in which the frequency adjustment and the temperature coefficient adjustment are performed using a mask on the electrode surface on the opposite side without using the hole of the pedestal. In FIG. 4, 1 'is a crystal chip on which an electrode film is formed, 2' is a pedestal, 18 'is a plasma source, 20'
Is a shutter and 22 'is a mask. 28 is an outer container. According to such a method, after the pedestal 2 'is attached to the container 28 with an adhesive or the like, the mounting of the crystal resonator chip 1' and the adjustment of the frequency and the temperature coefficient are possible. The degree of freedom in the assembling process is increased, and the configuration of the manufacturing line is facilitated.

[0013]

According to the present invention, GT is applied by sputtering of plasma.
The frequency adjustment and the temperature coefficient adjustment of the cut vibrator are performed. According to the present invention, there have been problems related to the adhesion of a deposited film, a problem that requires baking as a post-process for each deposition, a problem of a frequency shift depending on a deposition amount, and a trouble of closing a pedestal hole with an adhesive. And other problems can be solved. As a result, it is possible to manufacture a GT-cut resonator having higher quality while simplifying the manufacturing process.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of frequency adjustment of a GT-cut quartz resonator according to the present invention.

FIG. 2 is a diagram showing an example of temperature coefficient adjustment of a GT cut quartz crystal resonator according to the present invention.

FIG. 3 is a diagram showing a manufacturing apparatus for carrying out the present invention.

FIG. 4 is a diagram illustrating a method of adjusting a frequency and a temperature coefficient of a GT cut quartz crystal resonator according to the present invention without using a hole in a pedestal.

FIG. 5 is a view showing a pedestal for mounting a GT-cut quartz crystal resonator and a resonator chip on which an electrode film is formed before a vacuum sealing step.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Quartz-crystal oscillator chip (The electrode film is formed on the surface) 1 'Quartz-crystal oscillator chip (The electrode film is formed on the surface) 2 Pedestal 2' Pedestal 3 Temperature coefficient adjustment holes (two) 4 Frequency Adjustment holes (4 pcs) 5 Adhesive 6 Plug 7 Processing chamber 8 Load chamber 9 Unload chamber 10 Vacuum exhaust system of processing chamber 11 Vacuum exhaust system of load chamber 12 Vacuum exhaust system of unload chamber 13 Plasma generating gas ( 14) Gas for plasma generation (for frequency adjustment) 15 Gas for replacement (for processing chamber) 16 Gas for replacement (for load chamber) 17 Gas for replacement (for unload chamber) 18 Plasma source (temperature coefficient adjustment) 18 'Plasma source 19 Plasma source (for frequency adjustment) 20 Shutter (for temperature coefficient adjustment) 20' Shutter 21 Shutter (for frequency adjustment) 22 Mask (for temperature coefficient adjustment) 22 ' Disc 23 Mask (for frequency adjustment) 24 Transport system 25 Measurement jig (for temperature coefficient adjustment) 26 Measurement jig (for frequency adjustment) 27 Network analyzer 28 Container

Continuation of front page (72) Inventor Masaru Matsuyama 1110 Hirai-cho, Tochigi-city, Tochigi Pref.

Claims (2)

[Claims] 1. A manufacturing method for adjusting the frequency and temperature coefficient of a GT-cut quartz resonator, wherein the adjustment is performed by shaving the electrode surface of the quartz resonator chip using plasma. 2. A plasma source comprising two plasma sources, wherein the first plasma source cuts the electrode surface of the surface of the crystal resonator chip to adjust the temperature coefficient, and then the second plasma source continuously applies the same plasma chip to the resonator chip. 2. The crystal resonator manufacturing apparatus according to claim 1, wherein the frequency adjustment is performed by shaving the electrode surface in another region.