JP5940901B2 - Method for manufacturing element having electrode film - Google Patents

Description

The present invention relates to a method for manufacturing a device such as a tuning fork type quartz oscillator.

In vacuum vapor deposition, the ultimate pressure is generally 10 ⁻⁴ Pa, and the pressure during vapor deposition is 10 ⁻³ Pa to 10 ⁻² Pa. It is also practiced to heat the substrate to 300 to 400 ° C. for vapor deposition.

  2. Description of the Related Art Conventionally, there has been known a method of mainly measuring a pressure below atmospheric pressure using a tuning fork type crystal resonator (hereinafter also referred to as a resonator) (Patent Document 1). This is because the resonance impedance of the vibrator increases in proportion to the pressure in the molecular flow region and increases in proportion to the 1/2 power of the pressure in the viscous flow region. Is.

Since it is possible to measure in a wide pressure range from atmospheric pressure to 10 ⁻² to 10 ⁻³ Torr, it is recognized as an effective pressure measuring means.

In this measurement method using a vibrator, the vibrator is arranged in a space where pressure is to be measured, the vibrator is vibrated through an oscillation circuit, and the resonance impedance Z is obtained. From the difference ΔZ (= Z−Z ₀ ) between the measured resonance impedance Z and the intrinsic resonance impedance Z ₀ (generally a value at high vacuum and different from a CI value not measured under high vacuum). The gas pressure is measured.

  In this measurement method, the natural resonance impedance also changes due to a change in the ambient temperature of the vibrator. Therefore, there is a problem in that a measurement error increases on the low pressure side and accurate pressure measurement cannot be performed.

The natural resonance impedance Z ₀ varies by several kΩ over a wide temperature range (−20 to + 60 ° C.). On the other hand, the difference ΔZ is about several kΩ in the region of 10 ⁻¹ to 10 ⁻² Torr, and about several tens of Ω in the region of 10 ⁻² to 10 ⁻³ Torr, and the difference ΔZ decreases as the pressure decreases. That is, change in the natural resonance impedance Z ₀ of the oscillator varies with the temperature can not be ignored. This is the measurement limit of the pressure range when measuring pressure using a vibrator.

The applicant of the present application measures the resonance frequency f of the tuning fork type crystal resonator, obtains the temperature T of the tuning fork type crystal resonator from the resonance frequency f, and obtains the natural resonance impedance (Z ₀ + ΔZ _T ) and the resonance impedance Z at the temperature T. From the difference ΔZ = Z− (Z ₀ + ΔZ _T ), a method for measuring the gas pressure is proposed, and Patent No. 2077851 is obtained (Patent Document 2). This method has an effect of eliminating an error based on the temperature of the vibrator under measurement and measuring an accurate pressure.

However, since the pressure is calculated based on the correlation data between the resonance frequency f and the temperature T and the correlation between the temperature T and the natural resonance impedance (Z ₀ + ΔZ _T ), the data of the correlation data for each crystal resonator. There was a problem of increasing the cost by the number of man-hours and the arithmetic circuit.

Japanese Utility Model Publication No. 64-38547 Japanese Patent Publication No. 7-97060

The method of Patent Document 2 calculates pressure based on correlation data between the resonance frequency f and the temperature T, and correlation between the temperature T and the natural resonance impedance (Z ₀ + ΔZ _T ). However, there is a problem of increasing the cost by the amount of man-hours for collecting the correlation data and the arithmetic circuit.

In addition to improving the temperature dependence of the intrinsic resonance impedance (Z ₀ + ΔZ _T ), there is a need to lower the measurement lower limit of the quartz friction pressure gauge. Detection limit of the quartz friction manometer determined, the pressure sensitivity of the tuning fork crystal, by electrical noise inherent resonance impedance Z ₀ (maximum voltage change instantaneously, the voltage change of the voltage drift or per 1 ℃ in unit time) Is done. The pressure sensitivity has a practical limit depending on the size of the tuning fork crystal unit. On the other hand, the electrical noise is deeply related to the physical properties of the crystal as well as the temperature dependence of the natural resonance impedance Z ₀ , so that a theoretical analysis has been awaited.

From the experimental data regarding the temperature characteristics of the natural resonance impedance (Z ₀ + ΔZ _T ) and electrical noise of the tuning fork type crystal resonator, the present inventor has studied the internal friction during the vibration of the crystal resonator and the crystal piece. I was convinced that there were other factors besides the loss of vibration energy such as support system loss. And it discovered that the characteristic of the electrode film formed in a quartz oscillator had a big influence on a specific resonance impedance.

  A large number of tuning fork crystal units are manufactured simultaneously on a single crystal substrate. In such a case, each of a plurality of elements (for example, a tuning fork type crystal resonator) formed on the substrate includes an element portion having a rectangular cross section, and the element portions are opposed to each other in the thickness direction of the substrate. And a first side surface and a second side surface perpendicular to the first and second main surfaces. The electrode film is formed on all surfaces of the first and second main surfaces and the first and second side surfaces. In this case, the characteristics of the element such as the natural resonance impedance of the tuning fork type crystal resonator are particularly affected by the film thickness and film quality of the electrode film formed on the first and second side surfaces.

In some embodiments of the present invention, an electrode film having a good quality and an appropriate thickness is formed on all surfaces of the first and second main surfaces and the first and second side surfaces of the rectangular cross section formed in the element. An object of the present invention is to provide a method for manufacturing an element that can be used.

It is another object of the present invention to provide a method for manufacturing an element that improves the characteristic of the natural resonance impedance of a tuning fork type crystal resonator.

(1) In one embodiment of the present invention, an element formed on a substrate includes an element portion having a rectangular cross section orthogonal to the front and back surfaces of the substrate, and the element portion faces in the thickness direction of the substrate. A method of manufacturing the device by forming first and second main surfaces and first and second side surfaces orthogonal to the first and second main surfaces and forming an electrode film on the device portion. And
In a vacuum chamber, a substrate holder that is spaced apart from the film forming source and supported by the rotation shaft exposes the front and back surfaces of the substrate, supports the substrate, and drives the rotation shaft to tilt. A first film forming step of forming an electrode film on the first main surface and the first side surface by facing the first main surface and the first side surface to the film forming source;
After the first film formation step, the rotation axis is tilt-driven so that the first main surface and the second side surface face the film formation source, and the electrode film is formed on the first main surface and the second side surface. A second film forming step of forming a film;
After the first or second film forming step, the substrate is driven in reverse by driving the rotating shaft so that the second main surface and one of the first and second side surfaces face the film forming source. A third film forming step of forming the electrode film on the second main surface and one of the first and second side surfaces;
After the third film formation step, the rotation axis is tilt-driven so that the second main surface and the other of the first and second side surfaces face the film formation source, and the second main surface and second side surface A fourth film forming step of forming the electrode film on the other of
The present invention relates to a method for manufacturing an element having an electrode film.

  In one embodiment of the present invention, the substrate is supported by the substrate holder with the first and second main surfaces of the element exposed. Therefore, if the substrate holder is reversed by the rotation axis, the operation of forming the electrode films on the first and second main surfaces of the element can be realized without bringing the substrate into contact with the atmosphere.

  The rotation axis of the substrate holder can tilt the substrate by tilt drive. Therefore, the first or second side face that could not face the film forming source without tilt driving can be driven to tilt the substrate, whereby the first or second side face can face the film forming source. Thereby, in the 1st-4th film-forming process, it can form into a film on the 1st or 2nd side surface simultaneously with the 1st or 2nd main surface. Here, the meaning of facing the film forming source means that an arbitrary point on one of the first and second main surfaces and one of the first and second side surfaces, and a point on the film forming source, This means a positional relationship that can be connected with a straight line without interfering with the line.

  Here, during each of the first to fourth film forming steps, a total of four film forming steps, the first main surface, the second main surface, the first side surface, and the second side surface were formed twice. can do. As a result, an electrode film having a desired film thickness with a low electrical resistance can be formed on the first and second side surfaces, which are particularly difficult to form, without contacting the substrate with the atmosphere. it can.

(2) In one aspect of the present invention,
The electrode film includes a first electrode film formed on the substrate and a second electrode film formed on the first electrode film,
The film formation source includes a first vapor deposition source for vapor-depositing a material to be the first electrode film, and a second vapor deposition source for vapor-depositing a material to be the second electrode film,
The first electrode film is formed in the first to fourth film forming steps using the first evaporation source, and the second electrode is formed in the first to fourth film forming steps using the second evaporation source. An electrode film can be formed.

  In this case, for example, a refractory metal having high adhesion to the substrate, for example, can be selected as the first electrode film, and a metal material that forms a diffusion alloy with the refractory metal can be selected as the second electrode film.

(3) In one aspect of the present invention,
The electrode film includes a first electrode film formed on the substrate and a second electrode film formed on the first electrode film,
The film formation source includes a first vapor deposition source for vapor-depositing a material to be the first electrode film, and a second vapor deposition source for vapor-depositing a material to be the second electrode film,
In each of the first to fourth film forming steps, a diffusion alloyed electrode film of the first electrode film and the second electrode film is formed using the first vapor deposition source and the second vapor deposition source simultaneously. can do.

  In this way, unlike the above (2), the first and second electrode films can be simultaneously vapor-deposited from the first and second vapor deposition sources to achieve diffusion alloying of the first and second electrode films. . Thereby, the film formation time of the first and second electrode films can be greatly shortened. As described later, diffusion alloying can also be performed by heat treatment in the above (2), but diffusion alloying can be performed under a condition where the recrystallization temperature is lower by simultaneous vapor deposition. Also in this case, the formation of an oxide film between the first and second electrode films can be ignored.

(4) In one aspect of the present invention,
The film forming source is a vapor deposition source for depositing the electrode film,
When the distance between the deposition source and the substrate is L, the pressure for depositing the electrode film in the vacuum chamber is such that the mean free path of residual gas molecules in the vacuum chamber is 1000 times or more of L. The pressure can be

  In this way, the distance L between the vapor deposition source and the substrate is sufficiently smaller than the mean free path la of the residual gas molecules determined depending on the pressure during vapor deposition in the vacuum chamber, and the evaporated molecules and the residual gas molecules The probability of collision with can be reduced to 1/1000 or less. Thereby, it is possible to prevent impurities generated by the reaction with the residual gas in the gas phase in the vacuum chamber from being mixed into the electrode film. As a result, the occurrence of structural defects during film formation is suppressed, and when the element is, for example, a tuning fork crystal resonator, the natural resonance impedance of the tuning fork crystal resonator is lowered and the temperature coefficient of the natural resonance impedance is used. The temperature gradient can be reduced to reduce the temperature dependence of the natural resonance impedance.

(5) In 1 aspect of this invention, the pressure at the time of vapor deposition in the said vacuum chamber can be 1.33 * 10 < ^-5 > Pa or less. This pressure is a pressure at which the mean free path of residual gas molecules in the vacuum chamber is 1000 times or more of L.

(6) In one aspect of the present invention, the oxygen partial pressure during vapor deposition in the vacuum chamber can be 1 × 10 ⁻⁶ Pa or less. Thereby, it can prevent that an oxide film is formed in an electrode film. In particular, when the first and second electrode films are stacked as electrode films, an oxide film is prevented from being formed between the first and second electrode films, and the first and second electrode films are formed into a diffusion alloy. The heat treatment temperature to be reduced can be reduced.

  (7) In one embodiment of the present invention, the electrode film is heated while being heated at a film formation temperature lower than a recrystallization temperature of a vapor deposition material for forming the electrode film in a non-contact manner with the substrate. It can be deposited.

  Thereby, water and impurities on the surface of the substrate are removed to increase the adhesion between the substrate and the electrode film, and internal stress generated due to the difference in thermal expansion coefficient between the deposited electrode film and the substrate can be reduced. Moreover, the macroscopic shape of the deposited electrode film is not changed by forming the film at a substrate temperature lower than the recrystallization temperature.

  (8) In one embodiment of the present invention, the method may further include a step of heat-treating the substrate at a temperature higher than the film formation temperature after forming the electrode film.

  Thereby, structural defects such as vacancies, interstitial atoms, various transitions, stacking faults, and impurities (heterogeneous atoms / molecules) generated in the electrode film at the time of film formation can be reduced. By forming an electrode film with few structural defects, for example, the natural resonance impedance value and electrical noise of a tuning fork type crystal resonator can be lowered. Thereby, when a friction crystal pressure gauge is configured using this tuning fork type crystal resonator, the lower limit of the measurement pressure range can be lowered. In particular, when the first and second electrode films are stacked as electrode films, the first and second electrode films can be formed into a diffusion alloy. At this time, as described above, the formation of an oxide film between the first and second electrode films is prevented. Further, the heat treatment temperature for forming the first and second electrode films into a diffusion alloy can be the same as the time-division vapor deposition in the above (2) or lower than the recrystallization temperature of the vapor deposition material.

(9) In one aspect of the present invention, when the deposition rate when depositing the electrode film is Av, 10 ⁻⁵ g / (cm ² · S) ≦ Av ≦ 10 ⁻² g / (cm ² · S ).

From the relationship between the evaporation temperature of the electrode film material and the saturated vapor pressure curve for obtaining the above deposition rate, which is a practical range, when the pressure during deposition is 10 ⁻⁵ Pa or less, the electrode film material is completely evaporated. It doesn't matter.

  (10) In one aspect of the present invention, the substrate may be a quartz substrate, and the element may be a tuning fork type crystal resonator having two arms as the element portion.

  When the present invention is applied to a method for manufacturing a tuning fork crystal resonator, as described above, the temperature gradient based on the temperature coefficient of the natural resonance impedance of the tuning fork crystal resonator is reduced, and the temperature dependence of the natural resonance impedance is reduced. be able to. In addition, the natural resonance impedance value and electric noise of the tuning fork type crystal resonator can be lowered.

(11) Another aspect of the present invention is:
A vacuum chamber;
A film forming source disposed in the vacuum chamber;
A substrate holder disposed in the vacuum chamber and spaced apart from the film forming source, supporting the substrate by exposing a front surface and a back surface of the substrate, and supported by a rotating shaft to support the substrate;
Have
The substrate holder is controlled so that a rotation angle of the rotation shaft is controlled so that one of the front surface and the back surface of the substrate faces the film formation source, and a reversing drive for tilting the substrate. The present invention relates to a film formation apparatus that performs driving.

  According to another aspect of the present invention, the above-described method (1) of the present invention can be suitably carried out.

  (12) In another aspect of the invention, the deposition source is a deposition source of a deposition material, and the substrate supported by the substrate holder is placed in the vacuum chamber during the deposition of the electrode film. And a heating unit that heats the deposition material at a film formation temperature lower than a recrystallization temperature in a non-contact manner with the substrate.

  Thereby, water and impurities on the surface of the substrate are removed to increase the adhesion between the substrate and the electrode film, and internal stress generated due to the difference in thermal expansion coefficient between the deposited electrode film and the substrate can be reduced. Moreover, the macroscopic shape of the deposited electrode film is not changed by forming the film at a substrate temperature lower than the recrystallization temperature.

  (13) In another aspect of the invention, the heating unit heat-treats the substrate supported by the substrate holder at a temperature higher than the film formation temperature after the electrode film is formed. be able to.

  By heat-treating the electrode film at a substrate temperature higher than the film formation temperature after the film formation, structural defects in the electrode film generated during the film formation can be reduced. The heat treatment temperature may be lower than the recrystallization temperature or higher than the recrystallization temperature as long as it is higher than the temperature at the time of film formation. If the heat treatment temperature is lower than the recrystallization temperature, the macroscopic shape of the deposited electrode film is not changed. Even if the heat treatment temperature is equal to or higher than the recrystallization temperature, the macroscopic shape of the deposited electrode film is not changed as long as the heat treatment is performed for a short time.

It is sectional drawing of the quartz friction pressure gauge which concerns on embodiment of this invention. FIG. 2 is a schematic perspective view of a tuning fork type crystal resonator used in the quartz friction pressure gauge of FIG. 1. It is a figure which shows typically the element part of the two arm parts of a tuning fork type crystal resonator. It is a figure which shows an example of the electrode film formed in the main surface of a tuning fork type crystal resonator. It is a block diagram of a measurement circuit including a quartz friction pressure gauge. It is a figure which shows the relationship between the oscillation frequency and temperature of a tuning fork type crystal resonator (temperature-sensitive resonator). It is a figure which shows the relationship between impedance variation (DELTA) Z and pressure (Pa) of a tuning fork type crystal resonator. It is a figure which shows the temperature dependence of the natural resonance impedance of a tuning fork type crystal resonator. It is a figure which shows the relationship between the output voltage and pressure of a quartz friction pressure gauge. It is a figure which shows the equivalent circuit of a general tuning fork type crystal resonator. It is a figure which shows the expanded view of the electrode film shown in FIG. FIG. 12A to FIG. 12D are diagrams showing an equivalent circuit of a tuning fork type crystal resonator taking into consideration the thin film resistance of the electrode film. It is a figure which shows an example of the resistance value (measured value) of the electrode film formed in a tuning fork type crystal resonator. It is a figure which shows an example of resistance value (actually measured value) of two types of electrode films from which the film thickness formed in the side surface of the arm part of a tuning fork type crystal vibrator differs. It is a figure which shows the factor which improves the natural resonance impedance of a crystal oscillator. It is a figure which shows the natural resonance impedance characteristic of the crystal oscillator before and behind annealing in a high vacuum. It is a figure which shows the natural resonance impedance characteristic of the crystal oscillator before and behind annealing in a low vacuum. 18A to 18C are diagrams showing three types of electrical noise of the natural resonance impedance of the crystal resonator. FIGS. 19A to 19H are views schematically showing an outline of the manufacturing process of the tuning fork type crystal resonator. It is a figure which shows the film-forming apparatus (vapor deposition apparatus). FIGS. 21A and 21B are diagrams showing inversion driving of the substrate. 22A and 22B are diagrams showing tilt drive of the substrate. It is a figure which shows a 1st film-forming process. It is a figure which shows a 2nd film-forming process. It is a figure which shows a 3rd film-forming process. It is a figure which shows a 4th film-forming process. It is a figure which shows the collision probability of the vapor deposition molecule | numerator and residual gas molecule under the pressure at the time of the conventional vapor deposition. It is a figure which shows the collision probability of the vapor deposition molecule | numerator and residual gas molecule under the pressure at the time of vapor deposition of this embodiment. It is a figure which shows the relationship between the ratio of incident rate (nu) L of the residual gas molecule which injects into a board | substrate, and incident rate (nu) L of an evaporation molecule, and the thin film growth rate of Cr and Au. It is a figure which shows the relationship between the ratio of the incidence rate (nu) L of the residual gas molecule which injects into a board | substrate, and the incidence rate (nu) L of an evaporation molecule | numerator, and the thin film growth rate of Cr and Au in lower pressure than FIG. It is a figure which shows the natural resonance impedance characteristic of the tuning fork type | mold crystal resonator of this embodiment. It is a figure which shows the saturation vapor pressure curve of Cr and Au. It is a figure which shows the vapor deposition rate per unit area in which Cr and Au are vapor-deposited on a board | substrate.

  Hereinafter, preferred embodiments of the present invention will be described in detail. The present embodiment described below does not unduly limit the contents of the present invention described in the claims, and all the configurations described in the present embodiment are indispensable as means for solving the present invention. Not always.

1. Overview of quartz friction pressure gauge 1.1. FIG. 1 is a cross-sectional view of a quartz friction pressure gauge according to a first embodiment of the present invention. In FIG. 1, the pressure gauge 1 has a cylindrical case body 20 that forms a chamber 12 that communicates with a vacuum chamber 10. A lower end flange 22 of the case body 20 is fixed to the wall portion 14 of the vacuum chamber 10. The tuning fork type crystal resonator 30 is connected to the electrode 40. The electrode 40 is hermetically sealed and held, and the quartz crystal resonator 30 connected to the electrode 40 is disposed in the chamber 12 to provide an airtight seal structure 50 that is hermetically sealed and supported with respect to the case body 20. It has been. Furthermore, a filter member 60 that is held by the hermetic seal structure 50 and surrounds the crystal resonator 30 connected to the electrode 40 to form the measurement chamber 62 and that allows the measurement chamber 62 and the vacuum chamber 10 to communicate with each other is provided. ing. The filter member 60 is formed of, for example, a SUS (stainless steel) sintered body.

  The hermetic seal structure 50 is divided into, for example, a first seal body 52, a metal cylinder 54, and a second seal body 58. The first seal body 52 functions as a lever that hermetically seals and holds the electrode 40 in the cylindrical body 54 and electrically insulates the electrode 40. A threaded portion 56 is formed at the lower end of the cylindrical body 54 and is screwed into the filter member 60. The second seal body 58 is formed in a ring shape, and the cylinder body 54 is hermetically sealed in the case body 20 and held. The second seal body 58 also functions as an insulator that electrically insulates the case main body 20 and the cylindrical body 54 from each other when they are grounded.

1.2. Tuning Fork Type Crystal Resonator Structure As shown in FIG. 2, the tuning fork type crystal resonator 30 which is an example of an element having an electrode film on the element portion includes two arm portions 32A and 32B which are element portions. And a base 34 connecting one end of each of the arms 32A and 32B. Each of the two arm portions 32A and 32B has a rectangular cross section having a cross section width W and a cross section thickness t. The dimensions W and t of the rectangular cross-sections of the two arm portions 32A and 32B and the arm length La are designed so that the pressure dependency of the resonance impedance Z is increased. The dimensions of the two arm portions 32A and 32B will be described later.

  FIG. 3 schematically shows rectangular cross sections of the two arm portions 32A and 32B of the tuning fork type crystal resonator 30 shown in FIG. As shown in FIG. 3, the two arm portions 32A and 32B have first and second electrodes connected to the two first and second electrodes 40A and 40B constituting the electrode 40 shown in FIG. Patterns (electrode films) 70A and 70B are formed.

  In FIG. 3, the first main surface 32A1 and the second main surface 32A3, which are the two main surfaces of the arm portion 32A and face each other in the thickness direction of the arm portion 32A (the direction of the cross-sectional thickness t), One electrode pattern 70A is formed. The second electrode pattern 70B is formed on the first side surface 32A2 and the second side surface 32A4 which are opposite to each other in the width direction (direction of the cross-sectional width W) orthogonal to the thickness direction on the two side surfaces of the arm portion 32A. Is formed.

  On the other hand, two main surfaces of the arm portion 32B, which are opposite to each other in the thickness direction of the arm portion 32B (the direction of the cross-sectional thickness t), are the second main surface 32B1 and the second main surface 32B3. A pattern 70B is formed. On the two side surfaces of the arm portion 32B, the first electrode pattern 70A is formed on the first side surface 32B2 and the second side surface 32B4 that face each other in the width direction (direction of the cross-sectional width W) orthogonal to the thickness direction. Is formed.

  However, FIG. 3 schematically shows the connection between the first and second electrode patterns 70A and 70B and the electrodes 40A and 40B. Actually, as shown in FIG. 4, the two arms 32A and 32B are connected to each other. On each of the four surfaces (32A1 to 32A4, 32B1 to 32B4), one or both of the first and second electrode patterns 70A and 70B are formed in different regions insulated from each other.

  The tuning fork type crystal resonator 30 utilizes the fact that the piezoelectric effect generated in the crystal piece sandwiched between the first and second electrode patterns 70A and 70B and the oscillating electric field applied from the outside “resonate”. It causes mechanical vibration and electrical vibration (piezoelectric effect) at a certain frequency.

1.3. FIG. 5 is a block diagram of a measurement circuit 200 including the quartz friction pressure gauge 1. In FIG. 5, a current-voltage converter 210 that is connected to one end of the crystal resonator 30 and converts a current flowing through the crystal resonator 30 into a voltage, and an attenuator connected to the other end of the crystal resonator 30, for example, 1/10. The attenuator 220, the first full-wave rectifier 230 that rectifies the current from the 1/10 attenuator 220, the voltage from the first full-wave rectifier 230, and the reference voltage from the reference voltage source 240 are compared. Comparator 250, voltage-controlled attenuator 260 that further attenuates the output of 1/10 attenuator 220 based on the output voltage of comparator 250, and the summed output of voltage-controlled attenuator 260 and current-voltage converter 210 are rectified. A second full-wave rectifier 270.

  In FIG. 5, an analog / digital (A / D) converter 280 connected to the second full-wave rectifier 270, frequency measuring means for measuring the oscillation frequency of the crystal resonator 30, for example, a frequency counter 320, and 1/10 A frequency counter 290 connected to the attenuator 220 and a storage unit 300 are provided. Outputs of the A / D converter 280, the frequency counter 290, and the storage unit 300 are input to the arithmetic circuit 310, and the calculation result of the arithmetic circuit 310 is displayed on the display unit 320.

  Here, the current-voltage converter 210, the voltage controlled attenuator 260, the 1/10 attenuator 220, and the comparator 250 constitute a constant voltage drive type self-excited oscillation circuit. As shown in FIG. 3, when the electrodes 40A and 40B are AC driven at a constant voltage of, for example, ± 100 mV peak value, for example, at a frequency of 32 kHz, the output amplitude of the current-voltage converter 210 is inversely proportional to the resonance impedance (Z) of the crystal resonator. . Therefore, a value (1 / Z) reflecting the resonance impedance Z of the crystal resonator 30 is obtained as the output of the second full-wave rectifier 270. For example, the 24-bit resolution A / D converter 280 digitally converts the output of the second full-wave rectifier 270 and outputs it to the arithmetic circuit 310.

  Here, the relationship between the oscillation frequency of the crystal unit 30 and the temperature is as shown in FIG. 6, and the oscillation frequency f of the crystal unit 30 has a linear correlation with the actual temperature T. In this way, the crystal resonator 30 whose oscillation frequency changes linearly with respect to temperature is referred to as a temperature-sensitive resonator. Such a temperature sensitive oscillator can be formed depending on the cut angle of the crystal.

The output of the 1/10 attenuator 220 is a rectangular wave output correlated with the oscillation frequency f of the tuning fork type crystal resonator 30. Therefore, the frequency counter 290 counts the output frequency of the 1/10 attenuator 220, so that the temperature T correlates with the oscillation frequency f of the crystal resonator 30 and the temperature of the impedance of the crystal resonator 30 corresponding to the temperature T. The dependency value ΔZ _T can be detected.

On the other hand, the storage unit 300 is formed of RAM, PPROM, ROM, or the like, and stores the natural resonance impedance Z0 (value in high vacuum) of the crystal unit 30. Therefore, the arithmetic circuit 310 can output a voltage V _DC corresponding to ΔZ = Z− (Z ₀ + ΔZ _T ) based on the outputs of the A / D converter 280, the frequency counter 290, and the storage unit 300.

The difference ΔZ between the measured resonance impedance Z of the crystal unit 30 and the natural resonance impedance (Z ₀ + ΔZ _T ) of the crystal unit 30 at the temperature T corresponds to the gas pressure depending on the viscosity (concentration) of the gas. To do. The natural resonance impedance (Z ₀ + ΔZ _T ) is a value measured under high vacuum, and is different from a CI value not measured under high vacuum. The impedance change ΔZ is generated by the resonance between the quartz crystal resonator 30 in the resonance state and the friction between the gas and the like. The measurement principle of the quartz friction pressure gauge 1 is that the change in resonance impedance ΔZ of the quartz resonator 30 due to the frictional effect of gas is proportional to the first power of pressure in the molecular flow region (≧ 10 Pa), and the viscous flow region (≦ 100 Pa). Uses a characteristic proportional to the 1/2 power of the pressure. However, in the intermediate flow region (10 to 100 Pa), the mean free path of the gas and the size of the vibrator are the same, so the slip effect (the gap between the gas flow on the vibrator surface and the velocity of the vibrator surface) Phenomenon), the characteristics become complicated. FIG. 7 shows an example of the characteristics indicating the relationship between the impedance change ΔZ and the pressure (Pa) of the tuning fork type crystal resonator 30.

2. 2. Considerations of tuning fork-type crystal units and their causes 2.1. Problems of Tuning Fork Crystal Resonator As described above, the natural resonance impedance (Z ₀ + ΔZT) of the tuning fork crystal resonator 30 has a temperature dependency including a ΔZ _T component that depends on the temperature T. FIG. 8 shows the natural resonance impedance (Z ₀ + ΔZ _T ) of the tuning fork type crystal resonator 30. The natural resonance impedance _{(Z 0} + [Delta] Z _T) is generally the minimum value _{Z 0} becomes, [Delta] Z _T component negative temperature coefficient T1 (ppm / ℃) at a temperature lower than the temperature _{T P} becomes at a temperature _{T P,} the temperature _{T P} In the high temperature region, the ΔZ _T component has a positive temperature coefficient T2.

Problems of the tuning-fork quartz resonator 30, and that the minimum value Z _O of the natural resonance impedance CI of the vibrator 30 is large, is that a large temperature dependence due to [Delta] Z _T component. If the minimum value Z ₀ of the natural resonance impedance CI is large, the measured value of the resonance impedance change ΔZ of the crystal resonator 30 becomes small, and there is a problem that sensitivity at a particularly low pressure deteriorates as shown in FIG. Thereby, the lower limit of the pressure measurement is increased.

On the other hand, when a large temperature dependence due to [Delta] Z _T components, pressure corresponding to [Delta] Z _T component becomes error. In this regard, in Japanese Patent No. 2077851 filed by the present applicant, temperature compensation is performed by utilizing the temperature sensor function in which the crystal resonator 30 has a frequency proportional to the temperature as shown in FIG. . That is, the temperature T of the vibrator 30 is calculated from the frequency, the impedance value at the temperature T is corrected, and the lower limit of the pressure measurement is made, for example, 10 ⁻³ Pa. However, the temperature dependence due to [Delta] Z _T components smaller that the change is not good.

As another problem, since the resonance impedance change ΔZ is detected as a voltage, there is a problem of electrical noise. FIG. 9 shows the relationship between the DC voltage _VDC corresponding to the resonance impedance change ΔZ detected by the quartz friction pressure gauge 1 and the pressure (Pa). When the electrical noise is large, there is a problem that SN at a particularly low pressure deteriorates as shown in FIG. This also increases the lower limit of pressure measurement.

The temperature dependence of the natural resonance impedance (Z ₀ + ΔZ _T ) of the tuning fork type crystal resonator 30 has so far been determined to be “determined by the cut angle of the crystal”, but it is difficult to control and the physical property analysis of the crystal has been awaited. It was.

2.2. Consideration of the cause of the problem of the tuning fork type crystal resonator The present inventor has been said from the experimental data regarding the temperature characteristics and electric noise of the natural resonance impedance (Z ₀ + ΔZ _T ) of the tuning fork type crystal resonator 30. I was convinced that there were other factors besides the loss of vibration energy, such as internal friction during the vibration of the crystal unit and loss of the support system of the crystal piece. Therefore, from the viewpoint of crystal impedance, the equivalent circuit of the crystal resonator 30 generally used so far has been reviewed.

  FIG. 10 shows an equivalent circuit of a general crystal resonator. Here, the equivalent series resistance Rs represents a loss component of vibration energy such as internal friction at the time of vibration, support loss of the crystal piece, and acoustic loss. The equivalent series capacitance C1 corresponds to the elasticity of a spring or rubber when replaced with a mechanical motion. The equivalent series inductance L1 corresponds to the mass of the vibrating portion when replaced with a mechanical motion. The equivalent parallel capacitance C0 is a capacitance between the electrodes including the stray capacitance.

  Conventionally, the quartz friction pressure gauge 1 was thought to reflect the characteristics of the equivalent series resistance Rs in the equivalent circuit shown in FIG. However, in the equivalent circuit shown in FIG. 10, the interelectrode capacitance C0 is considered, but the resistances of the first and second electrode patterns (electrode films) 70A and 70B shown in FIG. 3 are not considered. The inventor has set a hypothesis that the electric resistance of the first and second electrode patterns 70A and 70B cannot be ignored from the viewpoint of impedance.

  FIG. 11 shows a developed view of the first and second electrode patterns 70A and 70B shown in FIG. In FIG. 11, R1 to R4 indicate resistance values of the electrode films 70A and 70B on the first and second side surfaces 32A2, 32A4, 32B2 and 32B4, and r1 to r4 indicate the first and second main surfaces 32A1, 32A3 and 32B1, respectively. The resistance values of the electrode films 70A and 70B of 32B3 are shown.

  12 (A) to 12 (D) show an equivalent circuit of the crystal resonator 30 in which the resistance values of the electrode films 70A and 70B are taken into consideration. FIG. 12A shows the resistance values R1 to R4 and r1 to r4 shown in FIG. FIG. 12B is an equivalent circuit diagram obtained by modifying FIG. 12A, and the crystal unit 30 is replaced with the equivalent circuit shown in FIG. In FIG. 12B, among the resistance values of the first electrode pattern 70A, the resistance values R1 and R2 of the first side surface 32A2 and the second side surface 32A4 are represented as a side combined resistance Ra, and the first main surface 32B1 and The resistance values r3 and r4 of the second main surface 32B3 are expressed as a main surface combined resistance ra. Similarly, in FIG. 12B, among the resistance values of the second electrode pattern 70B, the resistance values R3 and R4 of the first side surface 32B2 and the second side surface 32B4 are denoted as side surface combined resistance Rb, and the first main surface. The resistance values r1 and r2 of the 32A1 and the second main surface 32A3 are expressed as a main surface combined resistance rb. FIG. 12C shows a resonance state in the equivalent circuit diagram of FIG. 12B, and the crystal unit 30 is expressed as an equivalent series resistance Rs. FIG. 12D is an equivalent circuit diagram obtained by modifying FIG. 12C. The combined resistance R = Ra + Rb on the side surfaces 32A2, 32A4, 32B2, and 32B4, and the combined resistance on the main surfaces 32A1, 32A3, 32B1, and 32B3. r = ra + rb is shown. As shown in FIG. 12D, at the time of resonance, the side surface combined resistance R and the main surface combined resistance r and the equivalent series resistance Rs of the crystal unit 30 itself are connected in series.

  In conventional applications, there have been almost no examples utilizing the impedance at the time of resonance of the crystal unit 30. Until now, the crystal unit 30 has been used based on the fact that the vibration frequency is stable. In this case, since the resistance values of the electrode films 70A and 70B are excellent in temperature characteristics, the stray capacitance is small and the influence of the skin effect is small, the electrode films 70A and 70B have a performance that can withstand use even in an extremely high frequency region. I did not become a problem.

FIG. 13 is an example of measured values of the resistance values R1 to R4, r1 to r4, Ra, Rb, ra, rb, R, and r described above. Here, the resistance values R1 to R4 and r1 to r4 are: electric resistance value (Ω) = volume resistivity (μ · Ω · cm) × [length of electrode film (m) / cross-sectional area of electrode film (mm ² )] × 0.01. Here, the length La of the arms 32A and 32B of the crystal unit 30 shown in FIG. 2 is 2.7 mm, the width W = 0.365 mm of the rectangular cross section of the arms 32A and 32B, and the thickness t = 0. It was set to 13 mm.

  Further, the first and second electrode patterns 70A and 70B (electrode film) are two layers of a first electrode film (for example, Cr) and a second electrode film (for example, Au) as shown in FIG. The first electrode film Cr functions as an adhesion layer between the crystal unit 30 and the second electrode film Au.

  The first electrode film Cr is formed with a thickness of 50 mm on the first and second main surfaces 32A1, 32A3, 32B1, and 32B3, and with a thickness of 10 mm on the first and second side surfaces 32A2, 32A4, 32B2, and 32B4. The second electrode film Au is formed with a thickness of 200 mm on the first and second main surfaces 32A1, 32A3, 32B1, and 32B3, and with a thickness of 40 mm on the first and second side surfaces 32A2, 32A4, 32B2, and 32B4. Assuming that It is difficult to form an electrode film on the side surface compared to the main surface, and the reason why the film thickness on the side surface is thinner than the main surface will be described later. The length and cross-sectional area of the first electrode film Cr and the second electrode film Au used for calculation of the electric resistance values of the electrode films 70A and 70 are as shown in FIG. The volume resistivity of the first electrode film Cr at a temperature of 0 ° C. is 12.7 (μ · Ω · cm), and the volume resistivity of the second electrode film Au at a temperature of 0 ° C. is 2.05 (μ (Ω · cm).

The side surface combined resistance value R and the main surface combined resistance r calculated by the above formula are R + r = 10.4 + 0.62 = 11.02 kΩ from FIG. If the inherent resonance impedance Z ₀ (= R + r + Rs) of the crystal resonator 30 measured separately is about 15 kΩ, then Rs = Z ₀ − (R + r) = 3.76 kΩ. Therefore, side surfaces combined resistance value R and the major surface combined resistance value r is not negligible with respect to the equivalent series resistance Rs of the crystal oscillator 30, can have a significant impact on the natural resonance impedance Z ₀ of the crystal oscillator 30 itself I understand.

FIG. 14 shows an example in which the film thickness of the first electrode film Cr on the first and second side surfaces 32A2, 32A4, 32B2, and 32B4 is two types of 10 mm and 30 mm. With only the first electrode film Cr having a thickness of 10 mm, R + r = 10.6 kΩ from the value shown in FIG. 14, and with only the first electrode film Cr having a thickness of 30 mm, R + r = 3.98 kΩ from the value shown in FIG. The entire electric resistance value (R + r) including the same second electrode film Au as in FIG. 13 is 11.02 kΩ (when 10）) or 4.52 kΩ (when 30）). Therefore, the equivalent series resistance Rs of the crystal resonator 30 obtained by Rs = Z ₀ − (R + r) is assumed to be Rs = 3, assuming that the natural resonance impedance Z ₀ (= R + r + Rs) of the crystal resonator 30 is about 15 kΩ. .75 kΩ (when 10 Å) or Rs = 10.48 kΩ (when 30）). However, since the equivalent series resistance Rs of the same crystal unit 30 is unlikely to vary greatly depending on the thickness of the electrode film, by forming the electrode film on the side surface from 10 to 30 mm thick, It can be seen that the minimum value Z ₀ of the natural resonance impedance decreases.

From the above, the temperature characteristic of the natural resonance impedance (Z ₀ + ΔZ _T ) is not only the temperature characteristic of the equivalent series resistance Rs of the crystal unit 30, but also the side surface combined resistance value R and the main surface combination of the electrode films 70A and 70B. The temperature characteristic of the resistance value r is reflected.

By the way, the resistance value of the electrode film having a thin side surface has a negative temperature coefficient (ppm / ° C.) as in the case of a semiconductor (temperature and resistance value are inversely proportional), and the resistance value of the electrode film having a thick main surface is The temperature coefficient is positive (the temperature and the resistance value are in direct proportion) as with the metal that is the constituent material. Therefore, the reason why the temperature characteristics of the equivalent circuit of FIG. 12D including the side surface combined resistance value R and the main surface combined resistance value r become the characteristics shown in FIG. 8 is estimated as follows. That is, the negative temperature coefficient T1 than at lower temperature range the temperature T _P shown in FIG. 8 is dependent on the negative temperature coefficient aspects combined resistance R, the positive in the temperature range higher than the temperature T _P shown in FIG. 8 It is estimated that the temperature coefficient T2 depends on the positive temperature coefficient of the main surface combined resistance r. The temperature characteristic shown in FIG. 8 is presumed to be a combination of positive and negative temperature characteristics possessed by the equivalent circuit of FIG. 12D including the side surface combined resistance R and the main surface combined resistance r.

2.3. Thin Film Resistance Value The film formation process of the first and second electrode patterns (electrode films) 70A and 70B shown in FIG. 3 is as follows. First, some of the atoms that hit the quartz substrate rebound, and many remain on or near the substrate surface. Next, atoms fixed on the substrate, or atoms near the substrate remain in a gas or liquid state. Thereafter, when the thickness of the metal particles becomes, for example, 5 nm (about 10 times the diameter of the atoms), the metal particles are scattered in a dot shape. Thereafter, the dots grow in contact with each other, and an island appears when the thickness of the metal particles is, for example, 8 nm. When the thickness of the metal particles becomes 11 to 15 nm, the island gradually grows so as to leave a strait between the islands. When the thickness of the metal particles is, for example, 19 nm, the strait between the islands becomes smaller like a lake or a hole. When the thickness of the metal particles is, for example, 20 to 22 nm, the metal particles cover the substrate surface and become a thin film.

  From the above, the electrode films 70A and 70B formed on the first and second side surfaces 32A2, 32A4, 32B2, and 32B4, which are particularly difficult to form, have a large resistance value if they are island-shaped metal particles. It is not preferable. This is because, when the film thickness of the electrode films 70A and 70B is smaller than the mean free path of electrons (<10 nm), the electrons flow jumping along the islands, so that the electric resistance increases.

  When the film thickness of the electrode films 70A and 70B is larger than the electron mean free process, the electric resistance is lowered. However, if the film thickness is increased to some extent (for example, 50 nm), the resistance does not decrease. Further, the electrical conduction of the electrode films 70A and 70B does not become better than the bulk. Because the density is lower than the bulk and there are many internal defects.

  For the formation of the electrode films 70A and 70B, a film forming process such as sputtering or vapor deposition can be applied. In general, the electric resistance of the electrode films 70A and 70B is smaller in sputtering than in vapor deposition. This is because sputtering has a higher initial nuclear density.

  The resistance of bulk metal increases as the temperature increases. However, in the case of a very thin thin film such as an island-shaped metal particle group, the higher the temperature, the lower the resistance (the negative temperature coefficient T1 shown in FIG. 8). ). A higher temperature is considered to be chemically active and to exhibit properties close to semiconductors by reactions such as sub-oxidation. This is because it is better to be more active for electrons to fly between islands. When the film thickness of the electrode films 70A and 70B increases, the resistance temperature coefficient becomes positive as in the case of the bulk metal (positive temperature coefficient T2 shown in FIG. 8).

From the above, the electrode films 70A and 70B formed on the first and second side surfaces 32A2, 32A4, 32B2, and 32B4 are secured as thin films rather than island-like metal particle groups, so that the film thickness is 20 nm. The above is preferable. Thereby, for the reason described above, the negative temperature coefficient T1 in FIG. 8 can be changed to a positive temperature coefficient or a temperature gradient becomes small, and the intrinsic resonance impedance of the vibrator 30 having the electrode film. it is possible to further reduce the minimum value Z ₀ of the. However, since the resistance value does not decrease when the film thickness of the electrode films 70A and 70B formed on the first and second side surfaces 32A2, 32A4, 32B2, and 32B4 is increased to a certain extent, the film thickness is preferably 40 nm or less. Thereby, the film formation time can be shortened. For the same reason, the electrode films 70A and 70B formed on the first and second main surfaces 32A1, 32A3, 32B1, and 32B2 can have a film thickness of less than 80 nm. In this way, an increase in internal strain in the electrode film can be prevented and the internal stress that causes the characteristics of the tuning-fork type crystal resonator to become unstable can be reduced. The film thickness is selected.

2.4. Relationship between resistance characteristics of electrode film (thin film) and heat treatment Generally, vacancies, interstitial atoms, various transitions, stacking faults, and impurities (heterogeneous atoms / molecules) are known as the causes of structural defects in thin films. The resistance component resulting from these structural defects does not depend on temperature. As an impurity effect on the thin film, the atmospheric gas when forming the thin film affects the stress of the thin film. The effect of residual gas on the thin film relates to the generation of compressive stress in the thin film, and the greater the residual gas in the thin film, the greater the compressive stress.

FIG. 15 shows factors that improve the natural resonance impedance (Z ₀ + ΔZ _T ) of the crystal unit 30. As shown in FIG. 15, the minimum value Z ₀ of the natural resonance impedance of the crystal unit 30 is considered to be caused by a structural defect of the electrode films 70A and 70B which are thin films. On the other hand, [Delta] Z _T component of the natural resonance impedance of the quartz oscillator 30 is believed to be due to impurity effects. This point was verified by the following experiment.

  Compressive stress due to atmospheric gas when forming a structural defect (vacancies, interstitial atoms, various transitions, etc.) and thin film is higher than the temperature at the time of film formation, for example, annealing above the recrystallization temperature of thin film metal Can be reduced by doing This point will be described later.

FIG. 16 shows the intrinsic resonance impedance (Z ₀ + ΔZ _T ) of the crystal unit 30 obtained by annealing (300 ° C., 1 hour) the electrode films 70A and 70B under high vacuum (<10 ⁻³ Pa). The characteristics are shown. FIG. 17 shows the characteristic resonance impedance (Z ₀ + ΔZ _T ) of the crystal resonator 30 obtained by annealing (300 ° C., 1 hour) the electrode films 70A and 70B under high vacuum (<10 ² Pa). Show the characteristics.

In FIG. 16, the temperature characteristic of the natural resonance impedance (Z ₀ + ΔZ _T ) is that the minimum impedance value Z ₀ near 15 ° C. is Z ₀ 1 = 15.5 kΩ before annealing, After annealing, it decreases to Z ₀ 2 = 12.5 kΩ. In addition, it can be seen that the temperature coefficient of the resistance value also changes to a small value after annealing under high vacuum. This is because the structural defects of the electrode films 70A and 70B are removed by annealing the thin film under a high vacuum, and the effect of reducing the compressive stress due to impurities is exhibited by the high vacuum treatment.

On the other hand, in FIG. 17, the point where the impedance value Z ₀ 1 at the minimum near T _P 1 = 15 ° C. is decreased by about 3 kΩ from the minimum value Z ₀ 2 at the vicinity of T _P 2 = −15 ° C. The temperature coefficient of the resistance value is large on both the low temperature side and the high temperature side. In this phenomenon, although the structural defects of the electrode thins 70A and 70B are removed by the heat treatment at 300 ° C., the processing pressure is higher than that at the time of film formation, contrary to the processing under high vacuum, the electrode films 70A and 70B. This is because impurities are incorporated into the substrate.

2.5. Relationship between Electric Noise of Natural Resonance Impedance and Heat Treatment FIGS. 18A to 18C show three types of electric noise of the natural resonance impedance of the crystal unit 30. FIG. 18A to 18C show the results of measuring various electrical noises by enclosing the crystal unit 30 in a case whose pressure is reduced to 1.0 × 10 Pa or less. FIG. 18A shows the maximum instantaneous change ΔVS of the output voltage VDC. FIG. 18B shows the maximum change ΔV4 within 4 minutes of the output voltage VDC. FIG. 18C shows the maximum change ΔV of the output voltage VDC with respect to a temperature change ΔT of several degrees C., which has a larger variation than the room temperature change.

  In the electrode films 70A and 70B, which are thin films, all defects inherent to crystals such as vacancies, interstitial atoms, various dislocations, stacking faults, and crystal grain boundaries contained in the thin films are introduced during film formation. , Heterogeneous atoms and molecules are mixed as impurities. These defects cause scattering of all electrons, and the process of annihilation of defects having a small activation energy for annihilation of defects leads to instability of electrical properties. It is known that these defects contained in the deposited thin film are removed by annealing, and electrical characteristics are improved.

  As the crystal unit 30, 100 samples before and after annealing were prepared, and three types of electrical noise shown in FIGS. 18A to 18C were evaluated. The electrical noises ΔVs, ΔV4, and ΔV defined in FIGS. 18A to 18C had large noise values and a wide variation distribution before annealing heat treatment. However, it was found that after annealing, the noise value was small and the characteristics of many vibrators 30 were uniform. As a result, the electric noise of the natural resonance impedance and the heat treatment of the electrode film are greatly improved, indicating that the electrode thin film has a great influence on the natural resonance impedance value.

Here, FIG. 18A shows that the instantaneous maximum change voltage ΔVs of the output voltage VDC is 3.5 mV with respect to a change in room temperature. Then, the output voltage V _DC is 7.5 V, and the error due to the instantaneous maximum change voltage ΔVs is about 0.5%.

However, in order to reduce the error due to electrical noise to 1% or less at a higher vacuum pressure such as 1 × 10 ⁻² Pa, it is necessary to suppress the electrical noise to 1.5 × 10 ⁻⁵ V or less.

Conventionally, the instantaneous maximum change voltage ΔVs is the best value, and 2 × 10 ⁻⁴ V is obtained. However, in order to expand the lower limit of the pressure measurement range of the quartz friction pressure gauge 1, it is important to reduce the noise of the electrode thins 70A and 70B. When the electrode films 70A and 70B are formed by the film forming apparatus of this embodiment to be described later, noise reduction can be expected. Therefore, if the instantaneous maximum change voltage ΔVs can be 1.5 × 10 ⁻⁵ V or less, 1 × 10 ⁵ can be achieved. Measurement accuracy of 1% or less is possible even in a high vacuum measurement zone of ^-2 Pa.

3. 3. Electrode film formation method and film formation apparatus 3.1. Overview of Manufacturing Method of Crystal Resonator FIGS. 19A to 19H schematically show an overview of a manufacturing method of the crystal resonator 30, and the relationship between the thicknesses of the respective films is not considered. . FIG. 19A shows a cleaning process of the crystal substrate 100 having the front surface 100A and the back surface 1100B. 19A to 19H show only one region of the vibrator 30 in the quartz substrate 100, but in reality, a large number of vibrations are formed in one quartz substrate 100. A child 30 is formed.

  FIG. 19B shows a step of forming a resist film 102 on the front surface 100 </ b> A and the back surface 100 </ b> B of the quartz substrate 100. The resist film 102 is exposed, developed, and patterned.

  Using the patterned resist film 102A as a mask, the quartz substrate 100 is etched as shown in FIG. 19C, and the contour shape of the tuning fork type crystal resonator 30 is formed. FIG. 19C shows two arm portions 32A and 32B that are element portions of the tuning-fork type crystal resonator 30. FIG.

  19D shows, for example, the first electrode film 104 (Cr) and the second electrode film 105 (on the entire surfaces 32A1 to 32A4 and 32B1 to 32B4 (see FIG. 3) of the rectangular cross-sections of the two arms 32A and 32B. The process of forming Au) is shown. Details of the process illustrated in FIG. 19D will be described later.

  FIG. 19E shows a step of forming a resist film 106 over the entire surface of the second electrode film 105. The resist film 106 is exposed, developed, and patterned to become a mask 106A (see FIG. 19F).

  FIG. 19F shows an anisotropic etching process of the first and second electrode films 104 and 105 except for the region covered with the mask 106A. Thereby, the first and second electrode patterns 70A and 70B shown in FIG. 3 are formed. Then, as shown in FIG. 19G, the tuning fork vibrator 30 shown in FIG. 3 is formed by peeling the mask 106A. Here, the entire surface electrode film forming step in FIG. 19D is performed in an ultra vacuum in a vacuum chamber. Accordingly, the contamination of impurities and the formation of an oxide film, etc., which are caused by alternately taking in and out the substrate 100 in the air and vacuum during the formation of the first and second electrode patterns 70A and 70B as in the prior art, are completely ignored. can do. Although not shown, as described above, the first and second electrode patterns 70A and 70B are heat-treated by annealing or the like. The heat treatment of the first and second electrode patterns 70A and 70B can be performed in the same vacuum chamber after the film formation step in FIG.

FIG. 19H shows a step of coating the vibrator 30 with an insulating film 107 such as SiO ₂ as an additional step. Here, chromium Cr is exposed on the side of the two-layer electrode film (Au / Cr) constituting the first and second electrode patterns 70A and 70B in the course of electrode etching. For this reason, the oxidation of chromium Cr proceeds with time. By coating the vibrator 30 with the insulating film 107 such as SiO ₂ , the reliability of the vibrator 30 can be improved. In addition, the insulating film such as SiO ₂ forms a dense film. Therefore, the insulating film 107, for example, SiO ₂ can also serve as a barrier layer that suppresses the diffusion of different atoms from inside the vibrator 30 and the electrode films 70A and 70B. The process of FIG. 19H is after the tuning fork crystal resonator 30 is separated from the quartz substrate 100 after the tuning fork crystal resonator 30 is completed on the quartz substrate 100, and the tuning fork. It is desirable to carry out after bonding the quartz crystal resonator 30 to the hermetic terminal by soldering. Thereby, the solder portion can also be coated with the insulating film 107, and the corrosion resistance can be improved.

3.2. Outline of Electrode Film Deposition Apparatus (Vapor Deposition Apparatus) In order to form the electrode films 104 and 105 in FIG. 19E, a sputtering method or a vapor deposition method can be used. In the sputtering method, since the initial nuclear density is large, the electric resistance of the electrode films 104 and 105 can be reduced, a thin film of high boiling point metal or compound can be formed, and the substrate 100 is exposed to plasma, so that the substrate surface is cleaned and activated. There is an advantage in that However, the sputtering method has higher energy imparted to the atoms (−10 ¹ eV) than the vapor deposition method. Therefore, vacancies and interstitial atoms may be generated inside the crystal during the thin film formation process. These lead to structural defects and electrical noise. In that respect, vapor deposition has low energy imparted to atoms (10 ⁻¹ to 10 ⁰ eV), and can reduce structural defects and electrical noise. In the sputtering method, accelerated ions in the plasma or neutralized accelerated atoms are trapped by the substrate 100 as impurities, and surface atoms are struck into the substrate. As a result, the Peening effect occurs, and the compressive residual stress of the substrate or electrode film increases. In addition, the sputtering method does not prevent the generation of impurities. Even when these points are compared, the vapor deposition method is superior to the sputtering method. Therefore, in the following description, the film forming apparatus will be described with an example of a vapor deposition apparatus.

  FIG. 20 shows the vapor deposition apparatus 400. The vapor deposition apparatus 400 includes a vacuum chamber 401, a vapor deposition source 402 that is a film forming source disposed in the vacuum chamber 401, and a substrate holder 403 that is disposed in the vacuum chamber 401 so as to be separated from the vapor deposition source 402. .

  In the vacuum chamber 401, the substrate 100 supported by the transfer jig is carried in and out through a load lock chamber (not shown) for air-vacuum replacement and a gate valve.

The vacuum chamber 401 is evacuated to 10 ⁻⁶ Pa with a turbo pump after roughing with a dry pump. Thereafter, the pressure during vapor deposition is maintained at 1 × 10 ⁻⁵ Pa or less while evacuating with a cryopump.

  The evaporation source 402 includes a first evaporation source 402A that evaporates a material (for example, Cr) of the first electrode film 104 and a second evaporation source 402B that evaporates a material (for example, Au) of the second electrode film 105.

  The substrate holder 403 supports the substrate 100 by exposing the front surface 100A and the back surface 100B of the substrate 100 (only the upward-facing back surface 100B is shown in FIG. 20). For this reason, the substrate holder 403 can be fixed by sandwiching the front surface 100A and the back surface 100B at the periphery of the substrate 100.

  The substrate holder 403 is further supported (fixed) on the rotating shaft 404. The rotation shaft 404 is supported by bearings 405 and 405 and is driven to rotate or tilt by a driving unit provided outside the vacuum chamber 401.

  Opposite to the substrate 100 supported by the substrate holder 403, the vacuum chamber 401 can include a heating unit 406 that heats the substrate 100 by heating without contacting the substrate 100. The heating unit 406 may be resistance heating, a thermoelectron generating filament, or the like, but in this embodiment, the heating unit 406 is configured by an infrared lamp that can be non-contact heated and emits less gas. The heating unit 406 heats the substrate 100 at a temperature that takes into account the recrystallization temperature of the vapor deposition material (for example, 150 to 400 ° C. for Cr and Au).

  Here, the recrystallization temperature of the metal material is about 1/3 of the melting point. From the melting point of Cr of 1875 ° C. and the melting point of Au of 1063 ° C., the recrystallization temperature is 625 ° C. for Cr and 350 ° C. for Au. Become. For example, when the substrate 100 on which the electrode films 70A and 70B made of Cr and Au are formed is heated to a film formation temperature lower than the recrystallization temperature, for example, 150 ° C. during film formation, water and impurities on the substrate surface are removed. It is possible to increase the adhesion between the substrate 100 and the electrode films 70A and 70B, and to reduce the internal stress generated due to the difference in the thermal expansion coefficient between the deposited electrode films 70A and 70B and the substrate 100. In addition, by forming the film at a film formation temperature lower than the recrystallization temperature, the macroscopic shape of the electrode film to be deposited is not changed by, for example, depositing the deposition material in a monoatomic state. Further, after the film formation, the heating unit 406 heats the substrate 100 by heating the substrate 100 at a temperature higher than the film formation temperature, for example, a temperature higher than the recrystallization temperature, for example, 350 to 400 ° C. it can. By this heat treatment, thermal stress generated when the temperature of the substrate 100 decreases after the electrode film is formed, structural defects in the thin film and electrical noise generated during film formation can be reduced. The heating unit 406 can be housed in a housing unit 407 that cools, for example, water-cools the heating unit 406. Further, even if heat treatment is performed at a substrate temperature higher than the recrystallization temperature, it is considered that the macroscopic shape does not change if the heat treatment time is short.

  Between the housing portion 407 and the substrate holder 403, for example, a bottomed cylindrical reflector 408 and a shield plate 409 provided at the bottom, for example, can be provided. By the reflection function of the reflection plate 408, the infrared rays that are the heating unit 406 are efficiently condensed toward the substrate 100 and irradiated. For example, when the infrared lamp 406 is a point light source, the heating efficiency can be improved by arranging the infrared lamp 406 at one of the two focal points of the elliptical reflector 408 and the substrate 100 at the other. The shielding function of the shield plate 409 can prevent evaporation material from adhering to the infrared lamp 406 and the like.

  If necessary, a shutter provided between the vapor deposition source 402 and the substrate holder 403, a partition plate for preventing cross-contamination between the first and second vapor deposition sources 402A and 402B, a film thickness monitor unit, and the like Can be arranged.

3.3. Inversion Drive and Tilt Drive by Substrate Holder FIGS. 21A and 21B show inversion drive of the substrate 100. In FIG. 21A, since the back surface 100B of the substrate 100 is directed upward, the surface 100A in a downward state faces the vapor deposition source 402. Thereby, the material of the first electrode film 104 (for example, Cr) or the material of the second electrode film 105 (for example, Au) can be deposited on the surface 100A.

  In order to stack different electrode films on the surface 100A of the substrate 100, the heating source and the electron beam for heating the first and second vapor deposition sources 402A and 402B are switched.

  When the electrode film is formed on the surface 100 </ b> A of the substrate 100, the substrate holder 403 is driven in reverse by the rotation of the rotation shaft 404 by 180 degrees. Thereby, the back surface 100 </ b> B of the substrate 100 is disposed so as to face the vapor deposition source 402. In this manner, the substrate holder 403 and the substrate 100 can be easily inverted in the vacuum chamber 401 while the substrate 100 is held by the substrate holder 403.

  22A and 22B show tilt driving of the substrate 100. FIG. 22A and 22B, since the back surface 100B side of the substrate 100 is upward, the front surface 100A side in the downward state faces the vapor deposition source 402, but the tilt direction of the tilt angle (tilt angle) with respect to the horizontal plane Are positive and negative. If the clockwise tilt angle in FIG. 22A is, for example, + 30 °, the counterclockwise tilt angle in FIG. 22B is −30 °.

  23 and 24 show the first and second film forming steps performed in the normal rotation state (the surface 100A of the substrate 100 faces downward) shown in FIG. FIG. 23 shows the first film formation step after the tilt drive in FIG. 22A, and FIG. 24 shows the second film formation step after the tilt drive in FIG. FIG. 23 and FIG. 24 show the film forming process of the first side surface 32B2 and the second side surface 32A4 facing each other with the gap 33 between the two arms 32A and 32B of FIG.

  In the first film formation step of FIG. 23, the surface 100A (first main surfaces 32A1, 32B1) of the substrate 100 faces the vapor deposition source 402. In addition, the first side surface 32B2 of the arm portion 32B is tilted downward by the tilt drive and faces the vapor deposition source 402. As a result, the rising evaporation material is deposited on the surface 100A (first main surfaces 32A1, 32B1) of the substrate 100, travels through the gap 33, and is also deposited on the first side surface 32B2.

  In the second film formation step of FIG. 24 after the first film formation step of FIG. 23, the surface 100A (first main surfaces 32A1, 32B1) of the substrate 100 faces the vapor deposition source 402. In addition, the second side surface 32A4 of the arm portion 32A is tilted downward by the tilt drive and faces the vapor deposition source 402. Thereby, the rising evaporation material is deposited on the surface 100A (first main surfaces 32A1 and 32B1) of the substrate 100, and also proceeds through the gap 33 and is deposited on the second side surface 32A4. At this time, when the upper end of the first side surface 32B and the lower end of the second side surface 32A4 are positioned on substantially the same vertical line by tilt driving shown in FIG. 3, the vapor deposition material is placed above the substrate 100 via the gap 33. It is possible to reduce passing through.

  In the second film formation step of FIG. 24 after the first film formation step of FIG. 23, the surface 100A (first main surfaces 32A1, 32B1) of the substrate 100 faces the vapor deposition source 402. In addition, the second side surface 32A4 of the arm portion 32A is tilted downward by the tilt drive and faces the vapor deposition source 402. Thereby, the rising evaporation material is deposited on the surface 100A (first main surfaces 32A1 and 32B1) of the substrate 100, and also proceeds through the gap 33 and is deposited on the second side surface 32A4.

  25 and 26 show third and fourth film forming steps performed in the inverted state shown in FIG. 21B (the back surface 100B of the substrate 100 faces downward). For example, FIG. 25 shows a third film formation process after inversion driving 180 degrees inverted from the state of FIG. 24, and FIG. 26 shows a fourth film formation process after tilt driving from the state of FIG.

  In the third film forming step of FIG. 25, the back surface 100B (second main surfaces 32A3 and 32B3) of the substrate 100 faces the vapor deposition source 402. In addition, the first side surface 32B2 of the arm portion 32B is tilted downward by the tilt drive and faces the vapor deposition source 402. As a result, the rising evaporation material is deposited on the back surface 100B (second main surfaces 32A3 and 32B3) of the substrate 100, and proceeds through the gap 33 to be deposited on the first side surface 32B2.

  In the fourth film formation step of FIG. 26 after the third film formation step of FIG. 25, the back surface 100B (third main surfaces 32A3 and 32B3) of the substrate 100 faces the vapor deposition source 402. In addition, the second side surface 32A4 of the arm portion 32A is tilted downward by the tilt drive and faces the vapor deposition source 402. As a result, the rising evaporation material is deposited on the back surface 100B (third main surfaces 32A3 and 32B3) of the substrate 100, and proceeds through the gap 33 and is also deposited on the second side surface 32A4.

  The order of the first to fourth film forming steps can be changed as appropriate. The second film forming step is after the first film forming step, the fourth film forming step is after the third film forming step, and the third film forming step is the first film forming step or the second film forming step. Can be implemented later. Therefore, the order of the first, third, second, and fourth film forming steps and the order of the first, third, second, and fourth film forming steps may be used.

  Here, in each of the first to fourth film forming steps, the film thickness of the electrode film 104 deposited on the main surfaces 32A1, 32A3, 32B1, and 32B3 is defined as t11, and vapor deposition is performed on the side surfaces 32A2, 32A4, 32B2, and 32B4. The film thickness of the electrode film 104 is defined as t21. In each of the first to fourth film forming steps, the main surfaces 32A1, 32A3, 32B1, and 32B3 and the side surfaces 32A2, 32A4, 32B2, and 32B4 are each deposited twice. Therefore, when the final film thickness of the electrode film 104 on the main surfaces 32A1, 32A3, 32B1, and 32B3 is t12, and the final film thickness of the electrode film 104 on the side surfaces 32A2, 32A4, 32B2, and 32B4 is t22, the first to fourth components. When the time of the film process is equal, t12 = 2 × t11 and t22 = 2 × t21.

  Further, as is clear from FIGS. 23 to 26, in the first side surface 32B2 and the second side surface 32A4, the incident angle of the vapor deposition material is shallower than those of the first and second main surfaces, and the vapor deposition efficiency is poor. This means that the film thickness t22 of the electrode film on the first and second side surfaces 32A2, 32A4, 32B2, and 32B4 of the two arm portions 32A and 32B is the first and second of the two arm portions 32A and 32B. This is the reason why the thickness of the electrode film on the main surfaces 32A1, 32A3, 32B1, and 32B3 is thinner than t12. However, since the evaporation is performed twice on each of the side surfaces 32A2, 32A4, 32B2, and 32B4, the two arm portions 32A and 32B are applied to the first and second side surfaces 32A2, 32A4, 32B2, and 32B4. The first electrode film 104 (Cr) has a film thickness of 20 to 40 nm that is a continuous film.

  The first to fourth film forming steps described above can be performed while the substrate 100 is placed in the vacuum chamber 401 shown in FIG. Therefore, the substrate 100 does not come into contact with the air during the film formation, so that a natural oxide film is not formed on the electrode film. As shown in FIG. 19, when the first and second electrode films 104 and 105 are formed, the first electrode film 104 is formed in the first to fourth film forming steps using the first vapor deposition source 402A. After film formation and switching to the second vapor deposition source 402B, the second electrode film 105 can be formed in the first to fourth film formation steps. Also in this case, the first and second electrode films 104 and 105 can be formed while the substrate 100 is placed in the vacuum chamber 401 shown in FIG. Therefore, the substrate 100 comes into contact with the air during the formation of the first and second electrode films 104 and 105, and a natural oxide film is formed on the electrode film between the first and second electrode films 104 and 105. There is nothing.

  In each of the first to fourth film forming steps, a diffusion alloyed electrode film of the first electrode film 104 and the second electrode film 105 is formed using the first vapor deposition source 402A and the second vapor deposition source 402B simultaneously. May be. Thereby, the film formation time of the 1st, 2nd electrode films 104 and 105 can be shortened significantly. As described above, even if the first vapor deposition source 402A and the second vapor deposition source 402B are switched, diffusion alloying can be performed by heat treatment, but by simultaneous vapor deposition, diffusion alloying can be performed at a low substrate temperature. Also in this case, the formation of an oxide film between the first and second electrode films 104 and 105 can be ignored.

3.4. In this embodiment, when the distance between the deposition source 402 and the substrate 100 shown in FIG. 20 is L, the pressure for depositing the electrode film in the vacuum chamber 401 is the vacuum chamber. The pressure can be set so that the mean free path of residual gas molecules in 401 is 1000 times or more of L.

Here, a relationship of la = k / P is established between the mean free path (la) and the deposition pressure (P). k is a constant depending on the type of gas, and for air, k = 6.78 Pa · mm. If the pressure (P) during vapor deposition is 1.33 × 10 ⁻² Pa, the mean free process la is la = 500 mm. Therefore, in the case of a normal vacuum chamber, when the deposition pressure (P) ≦ 1.33 × 10 ⁻² Pa, the molecules in the vacuum chamber mainly collide with the chamber wall, not with each other.

FIG. 27 shows the probability of collision between evaporated molecules and residual gas molecules when the distance between the vapor deposition source 402 and the substrate 100 is L. However, the mean free path of residual gas molecules is la. From FIG. 27, it can be seen that when L = la, almost 60% of the vapor deposition molecules collide with residual gas molecules. Therefore, to make the collision probability between the residual gas and the vapor molecule very small, L << la is required. In the present embodiment, L ≦ 1000 × la is adopted as a condition satisfying L << la. In order to satisfy this, the deposition pressure (P) ≦ 1.33 × 10 ⁻⁵ Pa is established.

By setting the deposition pressure (P) in the vacuum chamber 401 to 1.33 × 10 ⁻⁵ Pa or less, the probability of collision between evaporated molecules and residual gas molecules is reduced to 1/1000 or less as shown in FIG. it can. Thereby, impurities generated by the reaction with the residual gas in the vapor phase in the vacuum chamber 401 can be prevented from being mixed into the electrode film which is a thin film.

In order to set the deposition pressure (P) in the vacuum chamber 401 to the order of 10 ⁻⁵ Pa, it is necessary to set the ultimate pressure Pu of the vacuum chamber 401 before the deposition to Pu <1 × 10 ⁻⁶ Pa. J Further, the oxygen partial pressure P _O2 at the time of vapor deposition in the empty chamber 401 is preferably P _O2 <1 × 10 ⁻⁶ Pa. When the oxygen partial pressure _{PO2 is} thus lowered, it is possible to prevent an oxide film from being formed on the first electrode film 104 after the first electrode film 104 (Cr) shown in FIG. 19 is formed. Thereby, the first electrode film 104 (Cr) and the second electrode film 105 (Au) are diffusion-alloyed at a substrate temperature lower than the recrystallization temperature of the vapor deposition material. If an oxide film is interposed between the first electrode film 104 (Cr) and the second electrode film 105 (Au), the film is heated to a temperature higher than the recrystallization temperature in order to form a diffusion alloy.

  The pressure during deposition will be considered from another point of view. Assuming that the remaining gas is air at a temperature of 293K, the following equation is true.

νL / νD = 7.4 × 103 (MDPL / ρak)
Where νL: incident of residual gas molecules incident on the substrate
νD: Incidence rate of evaporating molecules incident on the substrate
MD: Mass number of evaporated molecules
ρ: Density of the deposited film
PL: Total pressure of remaining gas in evaporation container during evaporation
aK: Growth rate of thin film

FIG. 29 shows the relationship between the thin film growth rate of Cr and Au at 1.33 × 10 ⁻³ Pa (air 293K) and the ratio between the incident rate νL of residual gas molecules incident on the substrate and the incident rate νD of evaporated molecules. It is a representation. The growth rate ak is actually in the range of 1 to 100 nm / s. Therefore, when the pressure is 1.33 × 10 ⁻³ Pa, νL / νD is in the range of 10 ⁻² to 1 as shown in FIG. 29, and it is obvious that the mixing of the residual gas has an effect.

  To reduce the contamination of residual gas molecules, it is necessary to lower the pressure or choose a very fast evaporation rate. It has been found so far that if the deposition film is deposited on the substrate at a high speed, there are many defects, and if it is slow, the film has few defects.

FIG. 30 shows the relationship between the thin film growth rate of Cr and Au at 1 × 10 ⁻⁶ Pa and the ratio between the incident rate νL of residual gas molecules incident on the substrate and the incident rate νL of evaporated molecules. Similarly to FIG. 29, under the condition of aK = 1 to 100 nm / s, νL / νD is in the range of 8 × 10 ⁻³ to 1 × 10 ⁻⁵ . In this way, by forming the film in the vacuum chamber 401 at a pressure of about 10 ⁻⁶ Pa, the residual gas can be suppressed to 1/100 or less as compared with the film forming conditions shown in FIG. it can. Thereby, structural defects and internal stress in the formed electrode film can be reduced.

The deposition rate per unit area at which Cr and Au are deposited on the substrate 100 is expressed by the following equation.
Av1 = 5.85x10-2 ・ Ps√ (MD / T)
Where Av1: Evaporation rate per unit area under ideal conditions
Ps: Saturated vapor pressure at temperature T
MD: Gram molecular weight of evaporated molecules
T: Absolute temperature of evaporation temperature

  Further, the saturated vapor pressure Ps is expressed by the following equation, where K1 and K2 are constants of materials, respectively.

Ps = K1 * e- ^{K2 / T}
FIG. 31 shows saturation vapor pressure curves of Cr and Au. The vapor deposition rate Av1 is determined using the saturated vapor pressure of the above equation, and the vapor deposition rate Av1 for Cr and Au is shown in FIG. Practically, an evaporation rate of 10 ⁻⁵ to 10 ⁻² (g / cm ² · s) is required. As is apparent from FIG. 32, in order to obtain a sufficient evaporation rate, generally, temperatures of 1350 to 1600K and 1600 to 2050K are required to dissolve the evaporation material and evaporate Cr and Au from the molten surface, respectively. The saturated vapor pressure at this temperature is 10 ⁻¹ to 10 ¹ Pa from FIG. 31 for Cr and Au, and vapor deposition is possible below this pressure.

3.5. Characteristics of Tuning Fork Crystal Resonator As described above, the pressure during vapor deposition in the vacuum chamber 401 is set to 1.33 × 10 ⁻⁵ Pa or less, and the substrate 100 is heated at the time of vapor deposition, so that the residual at a suitable thin film growth rate. A crystal oscillator electrode thin film with few structural defects and internal stress can be formed without being affected by gas molecules (especially oxygen).

The tuning fork type crystal resonator 30 manufactured as described above can have the characteristic resonance impedance characteristic shown in FIG. The minimum value Z0 = 12.5kΩ natural resonance impedance of a conventional tuning fork crystal _(T P = 15 ℃) is, in the present embodiment is reduced structural defects of the electrode film is Z0 = 10.0kΩ _{(T P} = 15 ° C). In addition, the conventional tuning fork type crystal resonator has a temperature dependency of ± 500 ppm / ° C. in a temperature T range of 15 ° C. ≦ T ≦ 55 °. In this embodiment, impurities in the electrode film are reduced. By doing so, it can be improved within ± 50 ppm / ° C. Further, by forming the first electrode film (Cr) on the first and second side surfaces 34A2, 34A4, 34B2, and 34B4 of the two arms 34A and 34B as a continuous film having a thickness of 20 to 40 nm, the temperature TP Also, the resistance value in the low temperature region has a positive temperature coefficient, and the temperature gradient can be reduced.

  Although the present embodiment has been described in detail as described above, it will be easily understood by those skilled in the art that many modifications can be made without departing from the novel matters and effects of the present invention. Accordingly, all such modifications are intended to be included in the scope of the present invention. For example, a term described with a different term having a broader meaning or the same meaning at least once in the specification or the drawings can be replaced with the different term in any part of the specification or the drawings.

  For example, a film-forming apparatus provided with a tilt and inversion drive mechanism for forming an electrode film on the main and side surfaces of an element on a substrate holder is a tuning-fork type crystal vibration used for various applications including pressure sensors and timing sensors. It is obvious that the present invention can be applied to the manufacture of elements such as a child and is not necessarily limited to a vapor deposition apparatus.

  When two electrode films are stacked, the first electrode film is not limited to Cr, but can be selected from other high melting point metals such as Ni, Ti, V, Nb, Ta, Hf, Mo, and Zr. The second electrode film is not limited to Au but may be Ag, Pt or the like having good adhesion to the refractory metal.

  DESCRIPTION OF SYMBOLS 1 Crystal type pressure gauge, 10 Vacuum chamber, 30 Crystal oscillator, 32A, 32B 1st, 2nd arm part (element part), 32A1, 32B1 1st main surface, 32A2, 32B2 1st side surface, 32A3, 32B3 1st 2 main surface, 32A4, 32B4 second side surface, 40 electrodes, 70A first electrode pattern (electrode film), 70B second electrode pattern (electrode film), 100 substrate (crystal substrate), 100A surface, 100B back surface, 104 First electrode film, 105 Second electrode film, 200 Measurement circuit, 210 Current-voltage converter, 220 Attenuator (1/10 attenuator), 230 First full-wave rectifier, 240 Reference voltage source, 250 Comparator, 260 Voltage controlled attenuator, 270 second full-wave rectifier, 280 analog / digital (A / D) converter, 290 frequency counter, 300 storage unit, 310 operation Part, 320 display part, 400 film forming apparatus (deposition apparatus), 401 vacuum chamber, 402 film forming source (deposition source), 402A first evaporation source, 402B second evaporation source, 403 substrate holder, 404 rotating shaft, 406 heating Part (infrared lamp), cross section width of W rectangular cross section, cross section thickness of rectangular cross section, length of La arm section

Claims (10)

The element formed on the substrate includes an element part having a rectangular cross section orthogonal to the front and back surfaces of the substrate, and the element part includes first and second main surfaces facing each other in the thickness direction of the substrate, A first and second side surface perpendicular to the first and second main surfaces, and a method of manufacturing the device by forming an electrode film on the device portion,
In a vacuum chamber, a substrate holder that is spaced apart from the film forming source and supported by the rotation shaft exposes the front and back surfaces of the substrate, supports the substrate, and drives the rotation shaft to tilt. A first film forming step of forming an electrode film on the first main surface and the first side surface by facing the first main surface and the first side surface to the film forming source;
After the first film formation step, the rotation axis is tilt-driven so that the first main surface and the second side surface face the film formation source, and the electrode film is formed on the first main surface and the second side surface. A second film forming step of forming a film;
After the first or second film forming step, the substrate is driven in reverse by driving the rotating shaft so that the second main surface and one of the first and second side surfaces face the film forming source. A third film forming step of forming the electrode film on the second main surface and one of the first and second side surfaces;
After the third film formation step, the rotation axis is tilt-driven so that the second main surface and the other of the first and second side surfaces face the film formation source, and the second main surface and second side surface A fourth film forming step of forming the electrode film on the other of
A process for producing an element having an electrode film comprising: In claim 1,
The electrode film includes a first electrode film formed on the substrate and a second electrode film formed on the first electrode film,
The film formation source includes a first vapor deposition source for vapor-depositing a material to be the first electrode film, and a second vapor deposition source for vapor-depositing a material to be the second electrode film,
The first electrode film is formed in the first to fourth film forming steps using the first evaporation source, and the second electrode is formed in the first to fourth film forming steps using the second evaporation source. A method for manufacturing an element having an electrode film, wherein the electrode film is formed. In claim 1,
The electrode film includes a first electrode film formed on the substrate and a second electrode film formed on the first electrode film,
The film formation source includes a first vapor deposition source for vapor-depositing a material to be the first electrode film, and a second vapor deposition source for vapor-depositing a material to be the second electrode film,
In each of the first to fourth film forming steps, a diffusion alloyed electrode film of the first electrode film and the second electrode film is formed by using the first vapor deposition source and the second vapor deposition source simultaneously. A method for manufacturing an element having an electrode film. In any one of Claims 1 thru | or 3,
The film forming source is a vapor deposition source for depositing the electrode film,
When the distance between the deposition source and the substrate is L, the pressure for depositing the electrode film in the vacuum chamber is such that the mean free path of residual gas molecules in the vacuum chamber is 1000 times or more of L. The manufacturing method of the element which has an electrode film characterized by the above-mentioned pressure. In claim 4,
A method for producing an element having an electrode film, wherein a pressure during vapor deposition in the vacuum chamber is 1.33 × 10 ⁻⁵ Pa or less. In claim 5,
A method for manufacturing an element having an electrode film, wherein an oxygen partial pressure during vapor deposition in the vacuum chamber is 1 × 10 ⁻⁶ Pa or less. In any one of Claims 2 thru | or 6.
In each of the first to fourth film formation steps, the substrate is heated at a film formation temperature lower than the recrystallization temperature of the vapor deposition material for forming the electrode film in a non-contact manner with the substrate. A method for producing an element having an electrode film, comprising depositing the electrode film. In claim 7,
A method for manufacturing an element having an electrode film, further comprising a step of heat-treating the substrate at a temperature higher than the film formation temperature after the electrode film is formed. In any of claims 5 to 8,
10 ⁻⁵ g / (cm ² · S) ≦ Av ≦ 10 ⁻² g / (cm ² · S), where Av is a deposition rate when the electrode film is deposited. The manufacturing method of the element which has this. In any one of Claims 1 thru | or 9,
The substrate is a quartz substrate;
The element is a tuning fork type crystal resonator having two arms as the element portion. A method of manufacturing an element having an electrode film.