JP2005090991A - Quartz friction vacuum gauge - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a quartz friction vacuum gauge which improves corrosion resistivity by preventing corrosion of electrode part of a quartz vibrator, prevents aging variation of temperature dependence concerning the intrinsic resonance impedance of the quartz vibrator and its inclination, capable of stably keeping the intrinsic resonance impedance constant, and improved in measurement accuracy of pressure, and reliability and life as a pressure measurement apparatus. <P>SOLUTION: The quartz friction vacuum gauge measures objective pressure by measuring resonance impedance of a quartz vibrator 18 which is varying with pressure variation. The quartz vibrator 18 comprises an electrode 32 consisting of bilayer structure of Au film 34, Cr film 33, and at least the side exposure part of the Cr film is covered with a coat film 35 for preventing corrosion of Cr film. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a quartz friction vacuum gauge, and in particular, is configured by using a tuning fork type crystal resonator or the like, and measures a pressure by measuring a change in resonance impedance of the tuning fork type crystal resonator or the like that changes according to a pressure change. It relates to a quartz friction vacuum gauge.

  In various semiconductor manufacturing apparatuses and electronic device manufacturing apparatuses that use a vacuum region, it is necessary to measure pressure in a wide range from an atmospheric pressure to a high vacuum region in accordance with start-up, maintenance, and various processes. For this reason, various vacuum gauges are used properly depending on the purpose of measurement.

In general, in a high pressure region (low vacuum region) of about 10 ^{5 to 1} Pa, it is based on a gas transport phenomenon typified by a heat conduction vacuum gauge such as a Pirani vacuum gauge, a quartz friction vacuum gauge, or a rotary viscometer. A vacuum gauge is used. In the pressure measurement during the process, a diaphragm vacuum gauge that satisfies the requirements of ease of pressure control and high accuracy is mainly used. On the other hand, in a low pressure region (high vacuum region) of 1 Pa or less, an ionization vacuum gauge typified by a bearer alpart type ionization vacuum gauge (hereinafter referred to as “BA type ionization vacuum gauge”) is widely used.

Here, the quartz friction vacuum gauge will be described. A quartz crystal is used in the quartz friction vacuum gauge. A crystal resonator widely used in the electronics field is a piezoelectric element and has a characteristic that an electrical impedance (resonance impedance) at the time of resonance changes according to the pressure of surrounding gas. The resonance impedance of the quartz resonator has a characteristic that it is proportional to the pressure in the molecular flow region and proportional to the 1/2 power of the pressure in the viscous flow region. Among them, the tuning fork type crystal resonator shows the largest resonance impedance change. A vacuum gauge constructed using such a quartz crystal resonator is a quartz friction vacuum gauge. According to the quartz friction vacuum gauge, the pressure of the gas is measured by utilizing the friction effect between the quartz crystal and the surrounding gas molecules (pressure factors), and the change in the resonance impedance of the quartz crystal The pressure value can be obtained by detecting. Specifically, the gas pressure is measured based on the difference ΔZ between the natural resonance resistance (Z ₀ ) of the crystal resonator and the measured resonance resistance (Z).

  As conventional techniques related to the quartz friction vacuum gauge, there are a quartz vacuum gauge disclosed in Patent Document 1 and a pressure measuring method using a tuning-fork type quartz vibrator disclosed in Patent Document 2.

  The quartz crystal vacuum gauge disclosed in Patent Document 1 is used by being placed in a measurement container attached to a vacuum container that is a pressure measurement target, even if the potential of the vacuum container is unstable. It is a quartz vacuum gauge that enables stable and accurate measurement without being affected. According to Patent Document 1, the above-described problem is achieved by devising a crystal resonator mounting structure in a measurement container attached to a vacuum container to be measured.

  The pressure measuring method using a tuning fork type crystal resonator disclosed in Patent Document 2 is a method for measuring a wide range of pressures using a tuning fork type crystal resonator. In the measurement of the gas pressure from the difference, the temperature of the tuning fork crystal resonator is obtained based on the resonance frequency for the intrinsic resonance resistance, and the resistance value corresponding to the obtained temperature is used. That is, the pressure measurement accuracy is improved by correcting the natural resonance resistance in consideration of the temperature condition.

  A method for manufacturing a crystal resonator is disclosed in Patent Document 3. The technology disclosed in Patent Document 3 relates to a crystal resonator that oscillates at a constant frequency and a method for manufacturing the crystal resonator that prevents the oscillation characteristics from deteriorating by preventing the change of the constant frequency over time. It is. According to this crystal resonator, the change with time of the frequency is prevented by preventing the change with time of the weight due to corrosion. That is, in this crystal unit, an insulating film is deposited on the two front and back electrodes to protect the electrode with a stable insulating film, and the change in weight over time due to corrosion of the electrode itself is suppressed. This prevents changes in frequency over time.

  Next, the structure of a tuning fork type crystal resonator used in a quartz friction vacuum gauge will be conceptually described with reference to FIGS. FIG. 5 is a perspective view of a main part of a tuning fork type crystal resonator, FIG. 6 is a diagram conceptually showing an electrode arrangement pattern on the surface of a square rod portion of the tuning fork type crystal resonator, and FIG. 7 shows a film structure of the electrode. FIG. The tuning fork type crystal resonator 101 has two parallel rectangular rod portions 101a and 101b. Two electrodes 102 and 103 are formed in a predetermined pattern on the surface of the tuning fork crystal unit 101. As a result, as shown in FIG. 6, the two rectangular rod portions 101a and 101b are provided with a pair of electrodes 102 and 103 on the upper and lower surfaces and the left and right surfaces in FIG. By supplying AC power of a certain frequency (for example, 32.8 KHz) between these electrodes 102 and 103 by an AC power source 104, the tuning fork type crystal resonator 101 is vibrated to generate a resonance state. In the crystal resonator 101, electrodes 102 and 103 are attached to predetermined surface regions including the surfaces of the square rod portions 101a and 101b. As a material for the electrodes 102 and 103, an Au (gold) film 105 is used as shown in FIG. The Au film has a thickness of about 200 nm. A Cr (chromium) film 106 is used as a base for the Au films of the electrodes 102 and 103 in order to improve the adhesion between the surfaces of the crystal resonator. The thickness of the Cr film is about 200 nm.

  According to the tuning fork type crystal resonator having the above-described structure, when the resonance impedance is measured in a state driven in a resonance state, a pressure change from atmospheric pressure to a high vacuum state of 0.01 Pa can be captured. In this case, since the tuning fork type crystal resonator is in a resonance state, the resonance impedance is almost equal to the resonance resistance. When measuring the pressure in a vacuum state based on the resonance impedance, the temperature of the resonance impedance is always corrected according to the frequency.

  The following problems are raised in the quartz friction vacuum gauge using the tuning fork type quartz resonator.

In various semiconductor manufacturing apparatuses and electronic device manufacturing apparatuses equipped with a quartz friction vacuum gauge, a reactive gas is often used because of various process condition requirements. For example, a fluorine-based gas or a chlorine-based gas typified by CF ₄ or CCl ₄ is used in a dry etching process that is indispensable as a semiconductor ultrafine processing technology, and an O ₂ gas is used in an ashing process. When these gases (gases) become plasma in a vacuum, they generate radicals that are chemically active. For this reason, in the quartz friction vacuum gauge using the conventional tuning fork type quartz vibrator described above, corrosion occurs in the exposed portion of the Cr film, which is the base film, in the electrodes of the quartz vibrator depending on the process conditions. When such corrosion of the Cr film occurs, a change with time occurs in the natural resonance impedance (mainly the natural resonance resistance) of the tuning fork type crystal resonator. For example, depending on the gas atmosphere, the value of the natural resonance impedance of the tuning-fork type crystal resonator starts to rise after several hours to several weeks, and is about 1.2 to 2 times. This means a change in the natural resonance resistance of the tuning fork type crystal resonator. For this reason, the change in the resonance impedance does not accurately correspond to the pressure change, and the pressure measurement accuracy decreases.

Further, the natural resonance impedance has a temperature dependency that increases as the temperature increases. The characteristic curve of temperature dependence of the natural resonance impedance has a characteristic that the slope of the increase becomes steep as the natural resonance impedance increases. If the natural resonance impedance of the crystal resonator changes due to corrosion of the electrode base film of the crystal resonator, it is necessary to frequently adjust the zero point in order to maintain pressure measurement accuracy. Therefore, it is desirable to suppress the change in the natural resonance impedance of the crystal resonator, which is a key for pressure measurement.
JP 2000-28465 A Japanese Patent Laid-Open No. 4-93735 (Japanese Patent Publication No. 7-97060) Japanese Patent Laid-Open No. 11-68501

  An object of the present invention is to measure a change in resonance impedance of a crystal resonator according to a change in pressure, and to measure a pressure in a reaction vessel that generates a plasma by introducing a gas such as halogen or oxygen. Therefore, it is intended to suppress the time-dependent change of the natural resonance impedance and further suppress the temperature-dependent change of the natural resonance impedance.

  In view of the above-mentioned problems, the object of the present invention is to prevent corrosion of the electrode portion of the crystal unit and improve its corrosion resistance, and further prevent the temporal dependence of the temperature dependence of the natural resonance impedance and the inclination of the crystal unit. Another object of the present invention is to provide a quartz friction vacuum gauge capable of stably maintaining a constant natural resonance impedance and improving pressure measurement accuracy and reliability and life as a pressure measurement device.

  In order to achieve the above object, the quartz friction vacuum gauge according to the present invention is configured as follows.

  A first quartz frictional vacuum gauge (corresponding to claim 1) is a quartz frictional vacuum gauge that measures a target pressure based on measuring a resonance impedance of a quartz resonator that changes in accordance with a change in pressure. The vibrator includes an electrode having a two-layer structure of an electrode film and a base film, and at least the side surface exposed portion of the base film is covered with a shielding film for preventing corrosion of the base film.

The quartz friction vacuum gauge measures the gas pressure based on the difference ΔZ between the natural resonance resistance (Z ₀ ) of the quartz crystal resonator and the measured resonance resistance (Z). In order to generate a resonance state in the crystal resonator, electrodes having a predetermined arrangement pattern are provided. This electrode has a two-layer structure consisting of an original electrode film and a base film for improving adhesion. In the quartz friction vacuum gauge, pressure factors such as reactive gas (gas) molecules and active species (radicals) come into contact with the quartz crystal resonator. In such a situation, active species such as O, H, and F are transported to the surface of the base film, causing a reaction, and there is a high possibility that a change in the amount of friction will occur. In order to prevent this, at least the side surface exposed portion of the base film is covered with a shielding film for preventing corrosion of the base film for the purpose of preventing the invasion of active species.

  In the first quartz friction vacuum gauge (corresponding to claim 2), the surface portion of the electrode in contact with the pressure factor (gas molecules, active species, etc.) is preferably covered with a shielding film in the first configuration. It is characterized by. In order to prevent intrusion of active species and the like, it is preferable to cover the entire surface portion of the electrode with a shielding film.

  A third quartz friction vacuum gauge (corresponding to claim 3) is preferably characterized in that, in each of the above-described configurations, the electrode film is an Au film and the base film is a Cr film.

  A fourth quartz frictional vacuum gauge (corresponding to claim 4) is characterized in that, in each of the above-described structures, the shielding film is preferably a film that prevents at least invasion of active species.

  The fifth quartz frictional vacuum gauge (corresponding to claim 5) is preferably characterized in that, in each of the above-described configurations, the material of the shielding film is any one of ceramics, metals, and plastic materials. As a method of forming the shielding film, coating, plating, vapor deposition or the like is used depending on the material.

  A sixth quartz friction vacuum gauge (corresponding to claim 6) is preferably characterized in that, in each of the above-mentioned configurations, the plastic material is polyimide or Teflon (registered trademark).

  According to the present invention, in a quartz friction vacuum gauge using a quartz resonator, the electrode uses a two-layer structure consisting of an electrode film and a base film, and particularly active at least on the side surface exposed portion of the base film such as a Cr film. Protected by applying a shielding film to prevent the invasion of seeds (radicals), etc., so that corrosion of the base film due to reactive gas and active species can be prevented. Even in a vacuum atmosphere exposed to a chemically active element, there is no deterioration in characteristics related to measurement performance or deterioration in life, and stable pressure measurement can be performed.

  DESCRIPTION OF EMBODIMENTS Preferred embodiments (examples) of the present invention will be described below with reference to the accompanying drawings.

  FIG. 1 shows a usage state of the quartz friction vacuum gauge according to the first embodiment of the present invention. Reference numeral 11 denotes a part of the vacuum container to be measured. The measured vacuum vessel 11 forms, for example, a vacuum chamber for processing a substrate. In the vacuum container 11 to be measured, the internal space 12 is brought into a required vacuum state, and a material gas, a process gas, or the like is introduced into the internal space 12 to generate plasma, and the substrate is loaded into the container. Is processed. The pressure in the internal space 12 of the vacuum container 11 to be measured is a measurement target of the quartz friction vacuum gauge according to the present embodiment.

  A vacuum gauge mounting portion 14 that forms a measurement opening 13 is provided in a part of the wall of the vacuum container 11 to be measured. A metal vacuum gauge container 15 that accommodates a quartz friction vacuum gauge is attached to the vacuum gauge mounting portion 14 so as to communicate with the measurement opening 13. The vacuum gauge container 15 has a cylindrical shape. In FIG. 1, the upper end is opened to form an opening, and a flange 15a is formed around the outside of the opening. The flange 15 a of the vacuum gauge container 15 is coupled to the mounting flange 14 a of the vacuum gauge mounting portion 14. The flange 15a and the mounting flange 14a are joined by a bolt or the like (not shown) in a vacuum sealed state. When the vacuum gauge container 15 is attached to the vacuum gauge attachment part 14, the measurement opening 13 and the opening 15 b of the vacuum gauge container 15 communicate with each other. The vacuum gauge container 15 can be freely attached to or detached from the vacuum gauge mounting part 14 of the vacuum container 11 to be measured. With this connection structure, the internal space of the vacuum gauge container 15 and the internal space 12 of the measured vacuum container 11 are connected.

  The lower end portion of the vacuum gauge container 15 in FIG. 1 is sealed with, for example, insulating glass 16, whereby the inside of the vacuum gauge container 15 is also kept in a vacuum. The insulating glass 16 is formed of an outer member 16a and an inner member 16b with the cylindrical shield 17 as a boundary. The cylindrical shield 17 accommodates, for example, a tuning fork type crystal resonator (hereinafter referred to as “crystal resonator”) 18. The cylindrical shield 17 is for shielding and protecting the crystal unit 18. The cylindrical shield 17 is preferably arranged in a coaxial positional relationship with the vacuum gauge container 15. The cylindrical shield 17 is fixed to the insulating glass 16 and attached to the vacuum gauge container 15. The lower end of the cylindrical shield 17 is further extended outward.

  The vacuum side end of the cylindrical shield 17 is arranged in a state of being inserted to the vicinity of the opening 15 b of the vacuum gauge container 15. A dust filter 19 is provided at the vacuum side end. The internal space of the cylindrical shield 17 and the internal space 12 of the measured vacuum vessel 11 communicate with each other through a dust filter 19. The dust filter 19 has a function of preventing dust from entering the internal space of the cylindrical shield 17.

  As described above, the quartz vibrator 18 is disposed inside the cylindrical shield 17. In FIG. 1, the crystal unit 18 is schematically depicted. Actually, for example, it has the crystal shape and electrode pattern structure shown in FIG. Electrodes 21 and 22 are formed on the surface of the crystal unit 18 based on two electrode patterns. The two electrode patterns are arranged in a predetermined facing state as described with reference to FIGS. 5 and 6 in the two rectangular rod portions 18a and 18b of the tuning fork type crystal resonator 18. In FIG. 1, for convenience of explanation, only the electrode portions formed on the front surface of the two rectangular rod portions 18 a and 18 b of the crystal resonator 18 are shown for the two electrode patterns.

  A lead wire 23 is connected to each base portion of the electrodes 21 and 22 formed on the surface of the crystal resonator 18 by soldering, and the other end of the lead wire 23 is fixed to the inner member 16b of the insulating glass 16 in a vacuum-sealed state. Each of the two lead pins 24 is spot-bonded.

  Each of the outer end of the cylindrical shield 17 drawn out of the insulating glass 16 and the outer end of the two lead pins 24 is led to the control circuit 26 by a cable (or connection line) 25 or the like. The outer end of the cylindrical shield 17 is connected to the ground 27 of the control circuit 26. Further, between the lead pins 24 of the electrodes 21 and 22, an alternating current having a required frequency is given from an alternating current power source (not shown) built in the control circuit 26.

  Based on the above configuration, the internal pressure of the vacuum container 11 to be measured is measured based on a signal input to the control circuit 26 via the electrodes 21 and 22, the lead wire 23 and the lead pin 24, and the cable 25. The control circuit 26 detects a change in resonance impedance (resonance resistance) in the resonance state of the crystal resonator 18 disposed in the internal space surrounded by the cylindrical shield 17, the dust filter 19, and the insulating glass 16. The control circuit 26 can measure the pressure of the internal space 12 of the vacuum container 11 to be measured by measuring the resonance impedance of the crystal resonator based on signals given from the electrodes 21 and 22 and detecting the change thereof. . This utilizes the characteristic that the resonance impedance, that is, the resonance resistance of the crystal unit 18 changes according to the pressure change.

  As described above, the resonance impedance, that is, the resonance resistance of the crystal unit 18 changes not only due to pressure change but also due to temperature change. Further, the crystal resonator 18 has a characteristic that its resonance frequency also changes according to a temperature change. Therefore, a quartz friction vacuum gauge configured to have high-precision measurement characteristics captures a temperature change based on a change in the resonance frequency of the crystal resonator 18 and corrects a resonance impedance according to the temperature change amount. Thus, it is configured to perform high-precision pressure measurement that is not affected by changes in ambient temperature. Note that the change (ΔZ) in resonance impedance converted into pressure is expressed by the following equation (Equation 1).

(Equation 1)
ΔZ = Z− (Z ₀ + Z _T )
here,
Z: Resonance impedance during pressure measurement
Z ₀ : natural resonance impedance
Z _T : Resonance impedance correction value at temperature T

FIG. 2 shows a cross section of the main part of a square rod portion of a tuning fork type (U-shaped) crystal resonator 18. FIG. 2 clearly shows the structure of the electrode. Reference numeral 31 denotes a partial cross-sectional portion of the square rod portion (18a, 18b) in the crystal resonator 18. This square rod portion is made of quartz, that is, SiO ₂ (silicon dioxide). 32 is an electrode. The electrode 32 is formed on the four sides of the side of the square rod portion. The electrode 32 is an enlarged view of the main part of the electrodes 21 and 22 corresponding to the two electrode patterns described above as a horizontal section. The electrode 32 is formed in a two-layer structure of a Cr film 33 and an Au film 34 on SiO _{2 serving} as a substrate portion, that is, a square rod portion 31. The Cr film 33 is a base film for improving the adhesion of the Au film 34, which is an original electrode, to the square rod portion 31. The thickness of the Au film 34 is, for example, 200 nm.

For example, a SiO ₂ coat film (silica film: ceramic) 35 is formed on the electrode 32 having the two-layer electrode structure as described above. The coating film 35 of the electrode 32 covers the entire side surface portions of the Cr film 33 and the Au film 34 and the entire outer surface portion of the Au film 34. Thus, the film portion of the two-layer structure forming the electrode 32 is protected by the coat film 35. Examples of the product of the coating film 35 include “polysilazane NP140 (registered trademark)” manufactured by Clariant Japan Co., Ltd.

  The coating film 35 is a shielding film that prevents reactive gas or radicals (active species) existing in the internal space 12 from entering the electrode 32 and prevents corrosion of the Cr film. If the coating film 35 is not provided, the reactive gas, radical, or the like enters the electrode 32 from the side surface or the like of the electrode 32 and is transported to the Cr film 33 to cause a reaction and corrode the Cr film 33. It will be. Accordingly, the coating film 35 is a shielding film that prevents the invasion of reactive gas, radicals, and the like and prevents the corrosion of the Cr film 3, and as a result, the corrosion resistance of the base film of the electrode 32 is enhanced.

  In the above, it is sufficient that the coating film 35 completely covers at least all of the exposed portion of the side surface portion of the Cr film 33. Furthermore, it is sufficient to completely cover all exposed portions of the side surfaces of the Cr film 33 and the Au film 34 of the electrode 32. However, it is not limited to this. As a method for applying the coating film 35, for example, coating is preferable. However, it is not limited to this.

  When the internal space 12 of the measured vacuum vessel 11 is depressurized so as to be in a required vacuum state and plasma or the like is generated, the reactive gas or radical generated in the internal space 12 of the measured vacuum vessel 11 is used for measurement. It moves to the internal space of the vacuum gauge container 15 through the opening 13. Such reactive gas or radical passes through the dust filter 19 and reaches the crystal unit 18 inside the cylindrical shield 17. The value of the resonance impedance of the crystal resonator 18 is changed by friction with the reactive gas or the like, and the pressure in the internal space 12 can be measured. In that case, according to the electrode 32 having the above-described structure in the crystal resonator 18, the side surface portion of the Cr film 33, which is inherently weak in corrosion resistance, is completely covered with the coating film 35. The corrosion can be prevented without being exposed to. Therefore, stable pressure measurement can be performed under various process conditions without causing deterioration of temperature compensation accuracy, shortening of the life, and lowering of reliability of the pressure measurement value.

  As described above, the reason why the above-mentioned action and effect can be obtained only by protecting the exposed portion of at least the side surface of the electrode 32 with the coating film 35 is that if the structure is allowed to corrode as in the conventional case, O, H, F And the like are transported to the surface of the Cr film forming the electrode 32 of the crystal resonator 18 and react to cause an electrode ohmic loss on the electrode side surface or the like, and a friction amount change between the electrode and the crystal portion. This is because the occurrence of these phenomena can be prevented by applying the coating film 35.

In the description of the above embodiment, the SiO ₂ coat film, that is, the ceramic shielding film is used to protect the electrode 32 portion. However, depending on the use environment of the quartz friction vacuum gauge, the shielding film is formed by coating polyimide. Is also effective. In addition, Teflon (registered trademark), SiN, Pt, or the like can be used as the shielding film. Moreover, instead of the shielding film by application, for example, alumina or the like may be used to coat the entire crystal unit 18 by vapor deposition.

  FIG. 3 is a cross-sectional view of the main part of a quartz friction vacuum gauge according to the second embodiment of the present invention, which is the same as FIG. 3, elements that are substantially the same as those described in FIG. In the quartz friction vacuum gauge according to the second embodiment, the Au plating film 36 is formed only on the formation region of the electrode 32 formed on the square rod portion 31 or the like of the crystal resonator 18 by the Au plating process, and the coating process is performed. Yes. Other configurations are the same as those in the first embodiment.

  For example, the Au plating film 36 is plated by applying a voltage to the lead wire 23 of the crystal resonator 18. Therefore, in this case, Au plating is performed on the surface of the existing Au film 34, the exposed portions of the side surfaces of the Cr film 33 and the Au film 34, the lead wires 23, the solder joints, and the like. . According to this, not only the portion of the Cr film 33 but also the corrosion resistance of the lead wire and the solder joint can be improved. The plating film thickness is about several microns to several hundred nanometers.

  In the quartz friction vacuum gauge according to the second embodiment, since the side surface portion of the Cr film 33 having low corrosion resistance is completely covered with the Au plating film 36, the corrosion resistance can be greatly improved.

  According to the quartz friction vacuum gauge according to the present invention, a vacuum atmosphere in which the quartz friction vacuum gauge is exposed to reactive gas or chemically active radicals such as a sputtering apparatus, a plasma CVD apparatus, a dry etching apparatus, an asher apparatus, etc. Therefore, stable pressure measurement can be performed without worrying about deterioration of characteristics and lifetime.

  The above embodiment has been described as an application example to a quartz friction vacuum gauge, but the present invention can also be applied to other measuring devices using a quartz resonator, such as a thermometer, a watch, a film thickness meter, and the like. it can.

An example of a protective coating film using a silica film will be described. In this embodiment, the coating film 35 is formed by applying polysilazane (SiH ₂ NH). Thereafter, it is left in the atmosphere in H ₂ O. As a result, an SiO ₂ film having a thickness of about 200 nm (0.2 μm) or less is formed.

FIG. 4 shows a change characteristic of the natural resonance impedance. The horizontal axis of the graph is the time axis, the unit is “time”, and the vertical axis is the natural resonance impedance. This graph shows the change characteristic of the natural resonance impedance of the B-A gauge built-in crystal resonator under a constant pressure in an oxygen plasma atmosphere. The characteristic A is that the silica film (SiO ₂ film) is coated, and the characteristic B is that the coating process is not performed. When the coating process is performed, it can be clearly seen that the natural resonance impedance of the crystal resonator is kept constant.

  The configurations, shapes, sizes, and arrangement relationships described in the above embodiments are merely shown to the extent that the present invention can be understood and implemented, and the numerical values and the compositions (materials) of the respective configurations are as follows. It is only an example. Therefore, the present invention is not limited to the described embodiments, and can be variously modified without departing from the scope of the technical idea shown in the claims.

  The present invention relates to pressure measurement in a film forming or processing chamber or the like of a semiconductor manufacturing apparatus or the like, or pressure measurement in a reaction vessel that generates a plasma by introducing a gas containing halogen gas or oxygen, and an ionization vacuum gauge. Used as a composite gauge.

It is sectional drawing which shows the attachment state at the time of use of the quartz friction vacuum gauge which concerns on 1st Embodiment of this invention. It is a fragmentary sectional view of the principal part of the square rod part of a tuning fork type crystal oscillator. It is a figure similar to FIG. 2 regarding the quartz friction vacuum gauge which concerns on 2nd Embodiment of this invention. It is a graph which compares and shows the change state of the natural resonance impedance of the crystal oscillator which performed the coating process based on this invention, and the crystal oscillator which does not perform a coating process. It is a perspective view which shows the external appearance of the conventional tuning fork type crystal resonator. It is sectional drawing which shows arrangement | positioning of the electrode of the two square rod parts of the conventional tuning fork type crystal resonator. It is sectional drawing which shows the laminated structure of the electrode part of the conventional two-layer structure.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Vacuum container to be measured 12 Internal space 14 Vacuum gauge attachment part 15 Vacuum gauge container 16 Insulating glass 17 Cylindrical shield 18 Tuning fork type crystal vibrator 18a Square rod part 18b Square rod part 21 Electrode 22 Electrode 32 Electrode 33 Cr film 34 Au film 35 Coat film (shielding film)
36 Au plating film

Claims (6)

  In a quartz friction vacuum gauge that measures a target pressure based on measuring a resonance impedance of a quartz crystal resonator that changes in accordance with a change in pressure, the quartz crystal resonator includes an electrode having a two-layer structure of an electrode film and a base film. A quartz friction vacuum gauge, wherein at least a side surface exposed portion of the base film is covered with a shielding film for preventing corrosion of the base film.   The quartz friction vacuum gauge according to claim 1, wherein a surface portion of the electrode in contact with a pressure factor is covered with the shielding film.   3. The quartz friction vacuum gauge according to claim 1, wherein the electrode film is an Au film and the base film is a Cr film.   The quartz friction vacuum gauge according to any one of claims 1 to 3, wherein the shielding film is a film that prevents at least the invasion of active species.   The quartz friction vacuum gauge according to any one of claims 1 to 4, wherein a material of the shielding film is any one of ceramics, metal, and plastic material. 6. The quartz friction vacuum gauge according to claim 5, wherein the plastic material is polyimide or Teflon (registered trademark).

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