Measurement system and repeating device

Abstract

To measure a resonance frequency of a quartz oscillator precisely by suppressing an influence of external noise.SOLUTION: A measurement system has a sensor head, a measurement unit, and a repeating device. The sensor head has: first and second front electrode sections; a piezoelectric vibrator having first and second rear electrode sections that oppose the first and second front electrode sections, respectively; and a shielding plate for shielding the second front electrode section composed of a material permitting passage of heat rays. The measurement unit measures the mass of a substance adhering to the surface of the piezoelectric vibrator. The repeating device includes a first wiring path for electrically connecting the first front electrode section and the first rear electrode section to the measurement unit, a second wiring path for electrically connecting the second front electrode section and the second rear electrode section to the measurement unit, and a switching circuit for alternately switching the first wiring path and the second wiring path, and is formed such that the first wiring path and the second wiring path are in a mutually symmetrical relationship.SELECTED DRAWING: Figure 11

Description

[Technical field]

[0001] The present invention relates to a measurement system that measures the amount of attached material in a vacuum or in the atmosphere from the change in the resonance frequency of a quartz oscillator and calculates the mass of the attached material, film thickness, film formation rate, etc., and a relay device used therein. [Background technology]

[0002] Conventionally, in film-forming equipment such as vacuum deposition equipment, a technique called QCM (Quartz Crystal Microbalance) that uses a quartz oscillator to measure minute changes in mass has been used to measure the thickness and deposition rate of a film formed on a substrate. This method utilizes the fact that the resonant frequency of a quartz oscillator placed in a chamber decreases due to an increase in mass caused by the adhesion of a deposition material. Therefore, it is possible to measure the thickness and deposition rate of a film by measuring the change in the resonant frequency of the quartz oscillator.

[0003] For example, Patent Document 1 discloses a detection device including a quartz crystal resonator having excitation electrodes formed on both the front and back sides of a quartz crystal substrate, an excitation means for applying a voltage between the front excitation electrode and the back excitation electrode to excite the quartz crystal resonator, and a detection means for detecting impurities from the change in the resonant frequency of the quartz crystal resonator. The front excitation electrode has a first electrode portion and a second electrode portion that are isolated from each other, and a cover body is arranged on the front side of the quartz crystal substrate to shield the first electrode portion from the vacuum atmosphere and to allow the passage of heat rays emitted from components in the vacuum chamber, and the detection means is configured to detect impurities from the difference between a first change in the resonant frequency detected by applying a voltage between the first electrode portion and the back excitation electrode and a second change in the resonant frequency detected by applying a voltage between the second electrode portion and the back excitation electrode. This makes it possible to accurately detect deposits on the surface of the quartz crystal resonator without being affected by temperature drift of the resonant frequency of the quartz crystal resonator.

[0004] Patent Document 2 discloses a frequency measuring device including an ion gun that irradiates an ion beam onto an electrode on a quartz crystal oscillator placed in a chamber to perform etching, a probe that contacts the electrode of the quartz crystal oscillator, a resonance circuit that forms an oscillation circuit together with the quartz crystal oscillator, a coaxial cable that connects the probe and the resonance circuit, and a control unit that monitors the resonance frequency of the quartz crystal oscillator based on the output signal of the resonance circuit and controls the ion gun. In this measuring device, the inner conductor of the coaxial cable connects the probe to the input or output end of the resonance circuit, a predetermined reference voltage is applied to the outer conductor of the coaxial cable, and the length of the coaxial cable is set so that the phase difference between the input and output signals of the feedback circuit is 180°. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2020-190455 A [Patent Document 2] JP 2009-60473 A Summary of the Invention [Problem to be solved by the invention]

[0006] In recent years, there has been a demand for more accurate rate detection and film thickness measurement under film formation conditions where the mass increase rate per unit time is extremely small, such as during ultra-low rate film formation where the film formation rate is extremely low. In particular, in a system in which a single quartz crystal oscillator to be measured has two vibration regions and the resonance frequency of the quartz crystal oscillator is measured while switching between these two vibration regions, such as the technology described in Patent Document 1, there is a demand for a technology that can measure the resonance frequency of the quartz crystal oscillator and its change over time without being affected by external noise.

[0007] In view of the above circumstances, an object of the present invention is to provide a measurement system that measures the resonant frequency of a quartz crystal oscillator by switching between two vibration regions, and that can measure the resonant frequency of a quartz crystal oscillator with high accuracy while suppressing the influence of external noise, and a relay device equipped with the same. [Means for solving the problem]

[0008] A measurement system according to one aspect of the present invention includes a sensor head, a measurement unit, and a relay device. The sensor head has a piezoelectric vibrator having first and second surface electrode portions and first and second back electrode portions facing the first and second surface electrode portions, respectively, and a shielding plate made of a material that allows heat rays to pass through and shields the second surface electrode portion. The measurement unit measures the mass of material attached to the surface of the piezoelectric transducer by using the correlation between transmission to the piezoelectric transducer and reception from the piezoelectric element, obtained by electrically sweeping near the resonant frequency of the piezoelectric transducer. The relay device has a first wiring path that electrically connects the first surface electrode portion and the first back surface electrode portion to the measurement unit, a second wiring path that electrically connects the second surface electrode portion and the second back surface electrode portion to the measurement unit, and a switching circuit that alternates between the first wiring path and the second wiring path, and is formed so that the first wiring path and the second wiring path are symmetrical to each other.

[0009] The first wiring path, the second wiring path and the switching circuit may be formed on a common wiring board, and the first wiring path and the second wiring path may be formed in a common or symmetrical wiring pattern on the wiring board.

[0010] The wiring board may have a shield layer formed of a conductor layer.

[0011] The relay device may further include a shield section that is made of a material having an electromagnetic shielding function and covers the wiring board.

[0012] The measurement unit may be configured to measure a film thickness or a film formation rate of a substance attached to a surface of the piezoelectric vibrator based on the difference between the amount of change per unit time in the resonant frequency of the piezoelectric vibrator when an AC voltage of a predetermined frequency is applied between the first surface electrode portion and the first back electrode portion and the amount of change per unit time in the resonant frequency of the piezoelectric vibrator when the AC voltage is applied between the second surface electrode portion and the second back electrode portion. Effect of the Invention

[0013] According to the present invention, in a system that measures the resonant frequency of a quartz crystal unit while switching between two vibration regions, the influence of external noise can be suppressed and the resonant frequency of the quartz crystal unit can be measured with high accuracy. [Brief description of the drawings]

[0014] [Figure 1] 1 is a schematic cross-sectional view showing a film forming apparatus including a measurement system according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a block diagram showing an example of the configuration of a measurement unit in the film forming apparatus. [Diagram 3] 2 is a typical equivalent circuit of a sensor device in the above measurement system. [Figure 4] FIG. 2 is a schematic cross-sectional view showing a configuration of the sensor device. [Diagram 5] FIG. 2 is an exploded cross-sectional view of the sensor device. [Figure 6] FIG. 2 is an enlarged cross-sectional view of a main part of the sensor device. [Figure 7] 3 is a top view of a piezoelectric vibrator in the sensor device. FIG. [Figure 8] FIG. 4 is a bottom view of the support as viewed from the piezoelectric vibrator side. [Figure 9] FIG. 2 is a top view of the piezoelectric vibrator as viewed from the support side. [Figure 10] FIG. 2 is a block diagram showing a configuration of the measurement system. [Figure 11]4 is a schematic diagram of a circuit configuration of a relay device in the measurement system. [Figure 12] 4 is a schematic diagram showing a cross-sectional structure of a main part of a wiring board in the relay device. FIG. [Figure 13] 11 is a schematic cross-sectional view showing another configuration example of the relay device. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In this embodiment, a thickness monitoring device for a film forming apparatus will be taken as an example of the measurement system.

[0016] 1 is a schematic cross-sectional view showing a film formation apparatus equipped with a film thickness monitoring device according to the present embodiment. In the present embodiment, a vacuum deposition apparatus will be taken as an example of the film formation apparatus 10. First, the basic configuration of the film formation apparatus 10 will be described.

[0017] [Film forming equipment] The film forming apparatus 10 includes a vacuum chamber 11 which is a film forming chamber, a deposition source 12 arranged inside the vacuum chamber 11, a stage 13 facing the deposition source 12, a sensor head 14 arranged inside the vacuum chamber 11, a vacuum pump 15 which maintains the inside of the vacuum chamber 11 at a predetermined vacuum atmosphere, and a measurement unit 17 which measures a film forming rate based on an output of the sensor head 14 as a sensor device and is configured to be able to control the deposition source 12. The sensor head and the measurement unit 17 constitute a film thickness monitoring device 20 for the film forming apparatus.

[0018] The deposition source 12 is configured to be capable of generating vapor (particles) of the film-forming material. In this embodiment, the deposition source 12 is electrically connected to a power supply unit 18, and constitutes an evaporation source that heats and evaporates the film-forming material to release deposition particles. The type of evaporation source is not particularly limited, and various methods such as a resistance heating type, an induction heating type, and an electron beam heating type can be applied. The film-forming material may be an organic material, a metal material, a metal compound material (e.g., a metal oxide, a metal nitride, a metal carbide, etc.), etc.

[0019] The stage 13 is configured to be capable of holding a substrate W, which is a target for film formation, such as a semiconductor wafer or a glass substrate, facing the deposition source 12.

[0020] As described later, the sensor head 14 has a built-in quartz crystal oscillator having a predetermined fundamental frequency (natural frequency). The surface of the quartz crystal oscillator is disposed in a position facing the deposition source 12, and is typically disposed in the vicinity of the stage 13.

[0021] The output of the sensor head 14 is supplied to a measurement unit 17. The measurement unit 17 is configured as a measurement device that measures the mass of the deposit (deposit) on the quartz crystal oscillator in a time series manner based on a change in the resonance frequency (resonance point) of the quartz crystal oscillator. The measurement unit 17 is further configured to measure the deposition rate of the deposition film and to control the deposition source 12 via a power supply unit 18 so that the deposition rate becomes a predetermined value.

[0022] The film forming apparatus 10 further includes a shutter 16. The shutter 16 is disposed between the deposition source 12 and the stage 13, and is configured to be capable of opening or closing an incident path of deposition particles from the deposition source 12 to the stage 13 and the sensor head 14.

[0023] The opening and closing of the shutter 16 is controlled by a control unit (not shown). Typically, the shutter 16 is closed at the start of deposition until the emission rate of the deposition particles from the deposition source 12 stabilizes. Then, when the emission rate of the deposition particles stabilizes, the shutter 16 is opened. This allows the deposition particles from the deposition source 12 to reach the substrate W on the stage 13, and a film formation process on the substrate W is started. At the same time, the deposition particles from the deposition source 12 reach the sensor head 14, and the thickness and film formation rate of the deposition film on the substrate W are monitored by the measurement unit 17.

[0024] [Measurement unit] 2 is a block diagram showing an example of the configuration of the measurement unit 17. The measurement unit 17 includes an oscillation circuit 41, a measurement circuit 42, a control unit 43, and a storage unit 44. The measurement unit 17 is configured to measure the mass of a substance (film material) attached to the quartz oscillator 140 by using the correlation between transmission to the quartz oscillator 140 and reception from the quartz oscillator 140 corresponding to the transmission, obtained by electrically sweeping around the resonant frequency of the quartz oscillator 140.

[0025] The oscillation circuit 41 and the measurement circuit 42 function as a network analyzer. The oscillation circuit 41 transmits, i.e., inputs, a sine wave signal of a predetermined frequency to the crystal oscillator 140 of the sensor head 14, thereby oscillating the crystal oscillator 140. The measurement circuit 42 is configured to receive an output signal from the crystal oscillator 140 and an input signal output from the oscillation circuit 41, and based on this, measures electrical characteristics such as the resonant frequency and phase of the crystal oscillator 140, and outputs the measured results to the control unit 43.

[0026] When a film is formed on the substrate W, the film material from the deposition source 12 also adheres to the surface of the quartz oscillator 140. The film material adhering to the surface of the quartz oscillator 140 changes the vibration frequency of the quartz oscillator 140 as a newly added mass at any time interval. The mass of the deposit on the surface of the quartz oscillator 140 correlates with the density of the deposit. In other words, by measuring the change in the vibration frequency of the quartz oscillator 140, the thickness (film thickness) of the film of the film material adhering to the surface of the quartz oscillator 140 can be obtained. The measurement unit 17 vibrates the quartz oscillator 140 by transmitting a signal, and indirectly measures the film thickness from the vibration waveform resulting from the vibration.

[0027] The measurement unit 17 uses a sinusoidal signal of a predetermined frequency as an emission signal to perform excitation. The excited quartz crystal oscillator 140 responds as a system including deposits attached to the surface. The measurement unit 17 receives the response of the quartz crystal oscillator 140, including a mechanical vibration phenomenon, as an electrical vibration waveform via the piezoelectric effect of the quartz crystal oscillator 140. The measurement unit 17 stores the waveform that is the received result, and analyzes the stored waveform. The vibration waveform of the quartz crystal oscillator 140 is stored in the memory unit 44. The measurement unit 17 extracts and outputs the film thickness included in the analysis result of the waveform.

[0028] The storage unit 44 is composed of a storage device such as a semiconductor memory, a hard disk drive, etc. The storage unit 44 stores a frequency response from the detection system including a vibration waveform of the crystal oscillator 140 when a sine wave signal of a predetermined frequency transmitted by the oscillation circuit 41 is input to the sensor head 14. The storage unit 44 further stores control programs for various processes executed by the control unit 43 described later, various parameters required for calculations, and the like.

[0029] FIG. 3 is a typical equivalent circuit of the sensor head 14. As shown in the figure, the quartz crystal unit 140 is shown as a parallel circuit of a series resonant circuit consisting of a motional capacitance C1, a motional inductance L1, and a series equivalent resistance R1, and a static capacitance C0. The series resonant circuit is an equivalent circuit including the mechanical vibration element of the quartz crystal unit 140. The static capacitance C0 includes, for example, the capacitance between the electrodes formed on the front and back surfaces of the quartz crystal unit 140, and the parasitic capacitance of a holder that holds the quartz crystal unit 140. The series equivalent resistance R1 indicates the loss components of vibration such as internal friction, mechanical loss, and acoustic loss when the quartz crystal unit 140 vibrates. In general, the higher the series equivalent resistance R1, the more difficult it is for the quartz crystal unit 140 to vibrate.

[0030] Methods for measuring the resonant frequency of the quartz crystal resonator 140 by excitation from the oscillator circuit 41 include a method for measuring the frequency at which the phase becomes zero, a method for measuring the frequency at which the susceptance, which is the imaginary component of the admittance, becomes zero, and a method for measuring the frequency at which the reactance, which is the imaginary component of the impedance, becomes zero.

[0031] [Sensor head] Next, the sensor head 14 as the sensor device of this embodiment will be described in detail. Fig. 4 is a schematic cross-sectional view showing the configuration of the sensor head 14, Fig. 5 is an exploded cross-sectional view thereof, and Fig. 6 is an enlarged cross-sectional view of a main portion thereof.

[0032] The sensor head 14 of the present embodiment includes a piezoelectric vibrator 50, a ring-shaped support 60, a connection terminal group 70, a cover member 80, and a base member 90.

[0033] (Piezoelectric vibrator) The piezoelectric vibrator 50 corresponds to the quartz crystal vibrator 140. The piezoelectric vibrator 50 has a vibrator body 51, a front electrode 52, a rear electrode 53, a front electrode terminal portion 520, and a rear electrode terminal portion 530, as shown in FIG.

[0034] The vibrator body 51 is a disk-shaped piezoelectric substrate made of quartz or the like. The vibrator body 51 has a front surface which is the upper surface side in FIG. 6 and a back surface which is the lower surface side. The front surface electrode 52 is formed on the front surface of the vibrator body 51. The back surface electrode 53 is formed on the back surface of the vibrator body 51.

[0035] The material constituting the vibrator body 51 is, for example, a piezoelectric element such as an AT-cut crystal vibrator, an SC-cut crystal vibrator, an IT-cut crystal vibrator, an FC-cut crystal vibrator, or an RC-cut crystal vibrator. The fundamental frequency of the vibrator body 51 is, for example, 3 MHz or more and 40 MHz or less, and is 15 MHz in this embodiment. When the attached mass is minute, the fundamental frequency of the crystal vibrator is set to a high value in order to increase the detection sensitivity of the mass. For example, when detecting a minute mass present in the air, a crystal vibrator having a fundamental frequency of, for example, several tens of MHz is selected.

[0036] The front electrode 52 and the back electrode 53 are excitation electrodes that vibrate the vibrator body 51 at its resonant frequency, and are typically made of a metal film such as Au, Ag, Pt, or Al. Metal films such as Au and Pt have better corrosion resistance than Al and the like, and can protect the front electrode 52 and the back electrode 53 from a corrosive environment. The front electrode 52 is patterned into an arbitrary shape on the surface of the vibrator body 51. The back electrode 53 is disposed at a position opposite the front electrode 52 across the vibrator body 51, and is patterned into a shape corresponding to the shape of the front electrode 52.

[0037] The surface electrode terminal portion 520 is formed on the surface of the vibrator body 51, and is connected to the surface electrode 52 via a connecting wire 52c. The surface electrode terminal portion 520 is typically formed at a predetermined position on the periphery of the surface of the vibrator body 51. The connecting wire 52c is formed linearly on the surface of the vibrator body 51 so as to connect between the surface electrode 52 and the surface electrode terminal portion 520. The surface electrode terminal portion 520 and the connecting wire 52c are formed of the same material and with the same thickness as the surface electrode 520.

[0038] The rear electrode terminal portion 530 is formed on the surface of the vibrator body 51, and is connected to the rear electrode 53 via a connecting wire 53c. The rear electrode terminal portion 530 is typically formed at a predetermined position on the periphery of the surface of the vibrator body 51. The connecting wire 53c is formed by folding back at the edge of the vibrator body 51 on the front and rear surfaces of the vibrator body 51 so as to connect between the rear electrode 53 and the rear electrode terminal portion 530. The rear electrode terminal portion 530 and the connecting wire 53c are formed of the same material and with the same thickness as the rear electrode 530.

[0039] The front electrode 52 and the back electrode 53 are each composed of a plurality of electrodes. In the piezoelectric vibrator 50 of this embodiment, two front electrodes 52 and two back electrodes 53 are arranged on the front and back surfaces of the vibrator body 51, as shown in FIG.

[0040] 7 is a top view of the piezoelectric vibrator 50. The surface electrode 52 has a first surface electrode portion 521 and a second surface electrode portion 522. The first surface electrode portion 521 and the second surface electrode portion 522 are disposed apart from each other and are formed in a symmetrical shape with the same area. A surface electrode terminal portion 520 is provided for each of the first surface electrode portion 521 and the second surface electrode portion 522, and each is disposed at a different position on the periphery of the surface of the vibrator body 51.

[0041] The back electrode 53 has a first back electrode portion 531 and a second back electrode portion 532. The first back electrode portion 531 is disposed at a position facing the first front electrode portion 521 across the vibrator body 50, and the second back electrode portion 532 is disposed at a position facing the second front electrode portion 522 across the vibrator body 50. The first back electrode portion 531 and the second back electrode portion 532 are formed to have the same area and a shape symmetrical to the first front electrode portion 521 and the second front electrode portion 522. The back electrode terminal portion 530 is provided for each of the first back electrode portion 531 and the second back electrode portion 532, or is provided in common with the first back electrode portion 531 and the second back electrode portion 532.

[0042] (Support) The support 60 is a circular plate member having a hollow portion 61, and is made of an electrically insulating material such as a ceramic material (e.g., quartz). By making the support 60 out of quartz, it is possible to reduce the difference in thermal expansion coefficient with the piezoelectric vibrator 50 (vibrator body 51) made of quartz.

[0043] The hollow portion 61 is a circular through-hole formed in the center of the support 60, and its inner diameter is smaller than the diameter of the piezoelectric vibrator 50. The support 60 is disposed opposite the surface of the piezoelectric vibrator 50, and has a support surface 62 that supports the peripheral portion of the surface of the piezoelectric vibrator 50. The support surface 62 supports the piezoelectric vibrator 50 so that it can vibrate via a connection terminal group 70. Note that it is preferable that the support 60 supports the piezoelectric vibrator 50 so as not to damage the symmetry of the first and second surface electrode portions 521, 522.

[0044] The support 60 exposes the surface electrode 52 of the piezoelectric vibrator 50 to the outside through the hollow portion 61. In this embodiment in which the surface electrode 52 is divided into a plurality of electrode portions, the support 60 is configured so that only the first surface electrode portion 521 is exposed to the outside through the hollow portion 61.

[0045] In this embodiment, the support 60 has a shielding plate 63 for shielding the second surface electrode portion 522, as shown in Fig. 4. The shielding plate 63 is a plate-shaped member fixed to the inner circumferential surface of the hollow portion 61, and is disposed in parallel to the second surface electrode portion 522 at a position facing the second surface electrode portion 522 of the piezoelectric vibrator 50 supported by the support member 60 (see Figs. 4 and 9). The shielding plate 63 is made of a material that allows the transmission of heat rays emitted from the deposition source 12. The shielding plate 63 is not limited to being provided in the hollow portion 62, and may be provided on the support surface 62 or on the upper surface of the support 60 opposite to the support surface 62, for example.

[0046] The support 60 further has a fitting portion 64 (see FIG. 5) into which a tip portion of a holding pin 83 for holding the support in a housing portion 81 of a cover member 80 described later fits. The fitting portion 64 is formed as a bottomed hole portion (recess), and at least one fitting portion 64 is provided on the outer circumferential surface of the support 60. This allows the support 60 to be stably held in the housing portion 81 of the cover member 80, and allows the support 60 and the piezoelectric vibrator 50 to be positioned in the circumferential direction relative to the cover member 80.

[0047] (Connection terminal group) The connection terminal group 70 is disposed between the support surface 62 of the support 60 and the peripheral portion of the front surface of the vibrator body 50. The connection terminal group has a first conductor layer 71 and a second conductor layer 72. The first conductor layer 71 is electrically and elastically connected to the front surface electrode terminal portion 520. The second conductor layer 72 is electrically and elastically connected to the back surface electrode terminal portion 530.

[0048] 6, the first conductor layer 71 has a first metallic land portion 711 formed on the support surface 62 of the support 60, and a conductive first elastic portion 712 provided between the first land portion 711 and the front surface electrode terminal portion 520. The second conductor layer 72 has a second metallic land portion 721 formed on the support surface of the support 60, and a conductive second elastic portion 722 provided between the second land portion 721 and the back surface electrode terminal portion 530.

[0049] The first land portion 711 and the second land portion 721 are made of a metal foil such as a copper foil or an aluminum foil. From the viewpoint of improving corrosion resistance, the land portions 711 and 721 are preferably made of a metal film such as Au or Pt. The first land portion 711 and the second land portion 721 are formed by patterning the metal foil formed on the support surface 62 of the support body 60 into a predetermined shape.

[0050] Fig. 8 is a bottom view of the support 60 as viewed from the piezoelectric vibrator 50. Fig. 9 is a top view of the piezoelectric vibrator 50 as viewed from the support 60.

[0051] In this embodiment, the front electrode 52 has first and second front electrode portions 521 and 522, and two front electrode terminal portions 520 corresponding thereto. The back electrode 53 has first and second back electrode portions 531 and 532, and two back electrode terminal portions 530 corresponding thereto. For this reason, as shown in FIG. 8, the first land portion 711 is provided at two locations corresponding to each front electrode terminal portion 520, and the second land portion 721 is provided at two locations corresponding to each back electrode terminal portion 530. These first land portion 711 and second land portion 721 are arranged at equal angular intervals on the support surface 62 along the circumferential direction of the support 60 as shown in the same figure.

[0052] The first elastic portion 712 and the second elastic portion 722 are composed of a conductive resin material, a metal coil, etc. The first elastic portion 712 is provided between the first land portion 711 and each of the front surface electrode terminal portions 520, and the second elastic portion 722 is provided between the second land portion 721 and each of the rear surface electrode terminal portions 530. The first elastic portion 712 and the second elastic portion 722 electrically and elastically connect the piezoelectric vibrator 50 to the support body 60 so as to be able to vibrate.

[0053] In determining the elastic modulus of the first elastic part 712 and the second elastic part 722, it is desirable to measure the temperature drift of the resonance frequency (for example, the first resonance frequency) and experimentally determine it so that the required measurement accuracy can be obtained, but it may also be determined by computer simulation. In either case, there is no problem as long as the stress applied to the piezoelectric vibrator 50 is dominated by the voltage (electric field) generated between the front and back electrodes 52, 53. In other words, the elastic modulus should be determined so that the effect of the mechanical stress (thermal stress) is, for example, 1 / 100 or less of the alternating electric field. If the elastic modulus is determined in this manner, errors caused by thermal stress can be suppressed even in an environment with temperature changes, and the required measurement accuracy can be achieved.

[0054] If the elastic modulus of each of the elastic parts 712, 722 is extremely low or if the elastic modulus of each of the elastic parts 712, 722 differs, stable resonance may not occur (a sudden transition of the resonance point may occur), and this may need to be avoided. In such a case, it is sufficient to provide three or more elastic parts, and to provide the elastic parts symmetrically (line symmetrically or equally angularly divided from the center of the piezoelectric vibrator 50). In this case, since the elastic parts represent a mechanical configuration, there is no need to ensure electrical continuity.

[0055] (Cover material) The cover member 80, together with a base member 90 described later, is configured as an exterior member of the sensor head 14. The sensor head 14 is placed in the vacuum chamber 11 with the cover member 80 facing the deposition source 12. The cover member 80 is, for example, a disk-shaped metal part, and has an accommodation portion 81 that accommodates the support 60, and an opening portion 82 that communicates with the hollow portion 61 of the support 60 accommodated in the accommodation portion 61.

[0056] The accommodation portion 81 is a circular recess capable of accommodating the support body 60. The depth of the accommodation portion 81 is not particularly limited, and in this embodiment, as shown in FIG.

[0057] The cover member 80 further has a retaining pin 83 for retaining the support 60 in the accommodation portion 81. The retaining pin 83 is inserted into an insertion hole 85 (see FIG. 5) that penetrates a part of the cover member 80 in the radial direction. The tip of the retaining pin 83 protrudes into the accommodation portion 81 and fits into a fitting portion 64 formed on the outer circumferential surface of the support 60 accommodated in the accommodation portion 81. The retaining pin 83 is constantly biased toward the accommodation portion 81 by a spring member 84 installed on the outer circumferential portion of the cover member 80. This allows the support 60 to be stably held in the accommodation portion 81. The number of retaining pins 83 is not limited to one, and may be provided in multiple locations.

[0058] The opening 82 is a through hole formed to communicate with a part of the bottom of the storage section 81, and communicates with the hollow section 61 of the support 60. The opening 82 has an inner diameter smaller than the outer shape of the support 60, and in this embodiment, is formed with a diameter substantially equal to the inner diameter of the hollow section 61. The opening 82 guides the deposition particles incident from the deposition source 12 to the piezoelectric vibrator 50 through the hollow section 61. The outer surface of the opening 82 is formed with a tapered surface 82a as shown in FIG. 4 in order to increase the incidence efficiency of the deposition material.

[0059] (Base material) The base member 90 is, for example, a disk-shaped synthetic resin (for example, PEEK (polyether ether ketone)) part having an upper surface 93 that abuts against the lower surface 86 of the case member 80, and is configured to be attachable to and detachable from the case member 80 by a ball plunger or a clamp member (not shown). The base member 90 has a bottomed recess 91 capable of accommodating the piezoelectric vibrator 50, and a plurality of metal contacts 92 that penetrate the bottom of the recess 91. The base member 90 may be configured as a metal part, in which case, an insulating coating is applied to the outer circumferential region of each contact 92 that contacts the recess 91 of the base member 90 (the outer circumferential region other than the tip portion).

[0060] The recess 91 forms a space large enough to accommodate the piezoelectric vibrator 50 supported on the support surface 62 of the support 60. In this embodiment, the recess 91 is formed to a size such that the entire support surface 62 of the support 60 held by the cover member 80 is exposed within the recess 91.

[0061] The multiple contacts 92 are inserted into insertion holes 94 that penetrate the bottom of the recess 91 in the thickness direction. The multiple contacts 92 include a first contact 921 and a second contact 922. The first contact 921 abuts against the first land portion 711 of the first conductor portion 71, and the second contact 922 abuts against the second land portion 721 of the second conductor portion 72.

[0062] As described above, in this embodiment, two each of the first conductor layers 71 and the second conductor layers 72 are provided corresponding to the first and second front surface electrode portions 521, 522 and the first and second back surface electrode portions 531, 532. Therefore, two each of the first contactors 921 and the second contactors 922 are also provided, for a total of four contactors arranged at equal angular intervals on the periphery of the piezoelectric vibrator 50 as shown in Fig. 8. Each contactor 92 is connected to the oscillation circuit 41 (Fig. 2) of the measurement unit 17.

[0063] A pogo pin equipped with a spring member 75 is used for each contactor 92. The spring member 95 biases the contactor 92 toward the piezoelectric vibrator 50. When the base member 90 is attached to the cover member 80 as shown in FIG. 4, each contactor 92 is pressed against the first and second land portions 711, 721 by the biasing force of the spring member 95. This electrically connects each electrode portion 521, 522, 531, 532 of the piezoelectric vibrator 50 to the oscillation circuit 41 of the measurement unit 17.

[0064] Each contactor 92 is desirably in the shape of a probe pin, for example. This is because the tip is needle-shaped (point-shaped on the contact surface) and the contact area is extremely small, so that electrical continuity can be ensured with a desired contact pressure with a small biasing force, and each contactor 92 is not constrained (microscopic slippage can be expected) even if thermal expansion occurs in the support 60 or base member 90. As a result, the piezoelectric vibrator 50 is similarly not affected, and a stable film formation rate and stable film thickness measurement can be achieved.

[0065] Furthermore, according to this embodiment, the support 60 that supports the piezoelectric vibrator 50 is arranged with its support surface 62 facing the base member 90, and therefore the following advantageous effects are obtained compared to a structure in which the support surface 62 is arranged on the cover member 80 side (hereinafter also referred to as the comparative example). First, since the contactors 921, 922 contact the conductor layers 71, 72 (land portions 711, 721) formed on the support surface 62 of the support body 60, the wiring length between the contactors 921, 922 and each surface electrode portion 521, 522 of the piezoelectric vibrator 50 can be made shorter than in the comparative example, thereby suppressing the inclusion of noise in the detection signal from the piezoelectric vibrator 50. Secondly, since the deposition particles reach the surface (first surface electrode portion 521) of the piezoelectric vibrator 50 through the hollow portion 61 of the support 60, the hollow portion 61 can achieve a collimator function for the deposition particles incident on the piezoelectric vibrator 50. Thirdly, since a shielding plate 63 for blocking the incidence of deposition particles on the second surface electrode portion 522 can be arranged on the support 60, there is no need to adopt a redundant configuration when installing the shielding plate 63, as compared to the comparative example.

[0066] [Repeater] In the film thickness monitoring device 20 of this embodiment, the piezoelectric vibrator 50 has two vibration regions, that is, a first vibration region 50A that is a region sandwiched between a first front electrode portion 521 and a first back electrode portion 531, and a second vibration region 50B that is a region sandwiched between a second front electrode portion 522 and a second back electrode portion 532. The measurement circuit 42 is configured to detect the difference in mass attached to the surface from the difference between a first change amount, which is a time change amount of the resonance frequency of the first vibration region 50A detected by applying an AC voltage between the first front electrode portion 521 and the first back electrode portion 522, and a second change amount, which is a time change amount of the resonance frequency detected by applying an AC voltage between the second front electrode portion 522 and the second back electrode portion 532. This makes it possible to accurately detect the attachment on the surface of the quartz crystal oscillator without being affected by the temperature drift of the resonance frequency of the quartz crystal oscillator. In other words, since it is configured to be able to cancel out anything other than the difference in the attached mass, the measurement system has a higher detection accuracy than other detection methods.

[0067] For example, by taking the difference between the first change amount and the second change amount, the effect of the temperature of the piezoelectric vibrator 50 is cancelled, so that it is possible to detect only the amount of change in the resonance frequency based on the change in the mass of the piezoelectric vibrator 50 with high accuracy without requiring a compensation circuit for compensating for changes in the environmental temperature. Moreover, not only for the piezoelectric vibrator 50, but also for devices such as the oscillation circuit 41 and the measurement circuit 42 that are subject to fluctuations in the environmental temperature, it is possible to perform highly accurate film thickness measurement or rate measurement without having to consider temperature compensation for these.

[0068] On the other hand, in recent years, there is a demand for more accurate rate detection and film thickness measurement under film formation conditions where the mass increase rate per unit time is extremely small, such as during ultra-low rate film formation where the film formation rate is extremely low. In particular, in a system in which a single quartz crystal oscillator to be measured has two vibration regions and measures the resonance frequency of the quartz crystal oscillator while switching between these two vibration regions, as in this embodiment, there is a demand for a technology that can measure the resonance frequency of the quartz crystal oscillator and its time change without being affected by external noise. In other words, there is a demand for a technology (a configuration that can more effectively offset factors other than the difference in the attached mass) that can detect a mass increase rate that is not sufficient to ensure the signal strength relative to the background noise, i.e., the S / N ratio.

[0069] Therefore, in this embodiment, in a system that measures the resonance frequency of a quartz crystal unit while switching between two vibration regions, a relay device 19 is provided that can measure the resonance frequency of the quartz crystal unit with high accuracy while suppressing the influence of external noise. Details of the relay device 19 will be described below.

[0070] 10 is a block diagram showing the configuration of a film thickness monitoring device 20 of this embodiment. In the figure, parts corresponding to those in FIG. 2 are given the same reference numerals, and detailed explanations thereof will be omitted.

[0071] 10, the sensor head 14 includes a piezoelectric vibrator 50 having a first vibration area 50A and a second vibration area 50B. The relay device 19 is connected between the sensor head 14 and the oscillation circuit 41 of the measurement unit 17. The relay device 45 may be configured as a part of the measurement unit 17.

[0072] The relay device 19 is for switching between transmission of a sine wave signal from the oscillation circuit 41 to the first vibration area 50A and transmission of a sine wave signal from the oscillation circuit 41 to the second vibration area 50B. The relay device 19 is connected to the oscillation circuit 41 via two first wiring cables 101, and is connected to the piezoelectric vibrator 50 (sensor head 14) via one second wiring cable 102. The other second wiring cable 102 is connected to the piezoelectric vibrator 50 via a current introduction terminal provided in the vacuum chamber 11. Both the first wiring cable 101 and the second wiring cable 102 are composed of coaxial cables.

[0073] The wiring cable 102 extending from the vicinity of the sensor head 14 to the current introduction terminal is preferably a wiring cable with low outgassing in consideration of the vacuum environment. As an example, a coaxial cable is used in which the portion (insulation) excluding the conductor portion of the coaxial cable is mainly made of fluororesin, there is no outer coating, and the outer conductor is in a bare state.

[0074] 11 is a schematic diagram of a circuit configuration of the relay device 19. As shown in the figure, the relay device 19 has a first wiring path 191, a second wiring path 192, and a switching circuit S. The first wiring path 191, the second wiring path 192, and the switching circuit S are formed on a common wiring board 190. As shown in the figure, in this embodiment, the relay device 19 has a configuration corresponding to a two-port measurement method (JISC6701) in which a measurement circuit for a crystal unit is formed by the central conductor (signal line) of each of the wiring cables 101, 102, and the outer conductor of each of the wiring cables 101, 102 is grounded.

[0075] The wiring board 190 is formed of a multilayer wiring board with a conductor layer formed on both sides, or a multilayer wiring board with a conductor layer formed on both sides and inside. The wiring board 190 is formed of a rigid board with an insulating layer made of glass epoxy resin, for example. The wiring board 190 has two terminal parts T1 and T2 to which the first wiring cable 101 (oscillating circuit 41) is connected, two terminal parts T3 and T4 to which the second wiring cable 102 (first vibration area 50A) is connected, two terminal parts T5 and T6 to which the second wiring cable 102 (second vibration area 50B) is connected, and a terminal part T7 to which the third wiring cable 103 described later is connected.

[0076] The terminals T1 and T2 are connected to a signal line (inner conductor) constituting the first distribution cable 101, and the terminals T3 to T6 are connected to a signal line (inner conductor) constituting the second distribution cable 102. The terminals T1 to T6 each include a ground terminal E, and the outer conductors of the distribution cables 101 and 102 are connected to a ground potential via the ground terminals E. The ground terminal E is also in contact with a conductive inner case 197 (described later) connected to a ground potential, and a so-called multi-point grounding circuit configuration is adopted. There is no substantial inconvenience even if a small gap is provided between the ground terminal E and the inner case 197, and the terminals are individually connected to a ground potential.

[0077] The first wiring path 191 electrically connects the first front electrode portion 521 and the first back electrode portion 531 forming the first vibration region 50A of the piezoelectric vibrator 50 to the measurement unit 17 (oscillating circuit 41). More specifically, the first wiring path 191 is a conductor pattern formed on the front surface of the wiring board 190, and includes a signal line connecting between the terminal portions T1, T2 and the terminal portions T3, T4 via a switch S1 described later. More precisely, the first wiring path 191 also includes a signal line connecting between the terminal portions T1, T2 and a switch S2 described later.

[0078] The second wiring path 192 electrically connects the second front electrode portion 522 and the second back electrode portion 532 forming the second vibration region 50B of the piezoelectric vibrator 50 to the measurement unit 17 (oscillating circuit 41). More specifically, the second wiring path 192 is a conductor pattern formed on the front surface of the wiring board 190, and includes a signal line connecting between the terminal portions T1, T2 and the terminal portions T5, T6 via a switch S2 described later. More precisely, the second wiring path 192 also includes a signal line connecting between the terminal portions T1, T2 and a switch S1 described later.

[0079] The switching circuit S has two switches S1 and S2 that enable alternate switching between a first wiring path 191 and a second wiring path 192. The switch S1 is a switching element for establishing or interrupting conduction between the terminals T1, T2 and the terminals T3, T4, and is installed in the middle of the signal line of the first wiring path 191. The switch S2 is a switching element for establishing or interrupting conduction between the terminals T1, T2 and the terminals T5, T6, and is installed in the middle of the signal line of the second wiring path 192.

[0080] The switches S1 and S2 each have, for example, two mechanical switches of a normally open contact type. For the switch S1, one switch part is provided between the terminal parts T1 and T3, and the other switch part is provided between the terminal parts T2 and T4, and these switch parts open and close in synchronization with each other. For the switch S2, one switch part is provided between the terminal parts T1 and T5, and the other switch part is provided between the terminal parts T2 and T6, and these switch parts open and close in synchronization with each other.

[0081] The switches S1 and S2 are controlled based on a control signal input to the switching circuit S via the terminal unit T7 so that the switches S1 and S2 operate alternately at a predetermined time period. That is, when the switch S1 is on, the switch S2 is turned off, and when the switch S2 is on, the switch S1 is turned off. The terminal unit T7 is connected to the control unit 43 via the third wiring cable 103, and the switches S1 and S2 are controlled to be turned on / off based on the control signal input from the control unit 43. The switches S1 and S2 include a solenoid coil L that converts the control signal (electrical energy) into opening and closing motion of each switch unit, and a diode D for noise suppression that passes a counter electromotive current generated in the solenoid coil L when the switch is off.

[0082] The switches S1 and S2, the two switch parts constituting the switches S1 and S2, and the conversion parts including the solenoid coil L and the diode D may be connected to the ground potential. Specifically, the above elements are housed in individual or common shield cases connected to the ground potential. This prevents electromagnetic noise caused by the operation of the switch changeover circuit S from being superimposed on the wiring paths 191 and 192.

[0083] FIG. 12 is a schematic diagram of a main part showing a cross-sectional structure of the wiring board 19. In this example, the wiring board 19 is a multi-layer board. A first wiring path 191 and a second wiring path 192 are formed on the surface of an insulating layer 193, and a copper foil 194 connected to a ground potential is formed on the back surface of the insulating layer 193. The first wiring path 191 and the second wiring path 192 are formed by patterning a conductor layer on the surface of the insulating layer 193 into a predetermined shape. The copper foil 194 is formed as a conductor layer on the outermost layer (back surface in FIG. 12) of the insulating layer 193 (based on each wiring path), and is typically formed of a solid metal film that is not patterned. The ground terminal E of each terminal portion T1 to T6 is connected to the copper foil 194 through a through hole (via) formed in the insulating layer 193.

[0084] 12, a conductive inner case 197 that covers the first wiring path 191 and the second wiring path 192 is provided on the surface of the insulating layer 193. The inner case 197 is a shielding component for preventing external noise from entering the wiring paths 191, 192 from the surface side of the insulating layer 193, and is formed in a shallow dish shape that is approximately rectangular in plan view. The periphery of the inner case 197 is positioned on the wiring board 190 so as to contact the ground terminals E of the terminal portions T1 to T6 (see FIG. 11). The inner case 197 is fixed to the wiring board 19 by a plurality of metal fixing pins 198 that penetrate the insulating layer 193, and is electrically connected to the copper foil 194.

[0085] As described above, the inner case 197 and the copper foil 194 can completely surround the first wiring path 191 and the second wiring path 192, and are configured to effectively block external noise from entering the wiring paths 191, 192, similar to the outer conductors of the respective wiring cables 101, 102. It should be noted again that the inner case 197 and the copper foil 194 are connected to the ground potential in order to function as a shielding layer.

[0086] In this embodiment, the first wiring path 191 and the second wiring path 192 are formed on the wiring board 190 so as to be symmetrical to each other. More specifically, in FIG. 11, the wiring paths 191 and 192 extending from the terminals T1 and T2 to the switching circuit S are formed so as to be symmetrical to each other. Being symmetrical to each other typically means that the first wiring path 191 and the second wiring path 192 are formed with the same line width, thickness, and line length. Furthermore, it is more preferable that the pattern layout of the wiring paths 191 and 192 is the same, or that they are formed with symmetrical wiring patterns so as to be line-symmetrical with respect to one axial direction in the plane of the wiring board 190.

[0087] As described above, by making the first wiring path 191 and the second wiring path 192 symmetrical, it is possible to make the high-frequency characteristics of the first wiring path 191 and the second wiring path 192 as viewed from the terminal portions T1, T2 approximately identical (even when switched by switches S1 and S2).As a result, a configuration can be achieved in which the resonant frequency of the quartz crystal oscillator does not change due to the wiring path when the two vibration areas 50A, 50B of the piezoelectric oscillator 50 are switched.

[0088] In other words, the symmetrical relationship is a pattern layout in which the change in the resonant frequency caused by the switching is 1 / 100 or less of the change caused by the mass increase per unit time in terms of the S / N ratio, and the configuration can be determined by using an experiment or a simulation. In terms of the pattern layout, the first wiring path 191 and the second wiring path 192 are made to be visually contrastive. Typically, a symmetrical pattern layout as described above is first designed, and then the change in the resonant frequency caused by the switching is confirmed. At this time, if there is an inconvenience in measuring the rate of mass change per unit time, the pattern layout can be redesigned to maintain a more symmetrical relationship, the signal lines from each terminal part to the switches S1 and S2 can be shortened, or the high frequency characteristics of one of the signal lines can be adjusted (for example, by resistor grounding or capacitor grounding), so that the change in the resonant frequency caused by the switching is less than the desired fluctuation amount.

[0089] This makes it possible to equalize the noise superimposed on the first wiring path 191 and the second wiring path 192, so that when measuring the film thickness of the deposition material from the difference between a first change amount, which is the time change in the resonant frequency of the first vibration region 50A, and a second change amount, which is the time change in the resonant frequency of the second vibration region 50B, as described below, it becomes possible to cancel out the noise superimposed on each wiring path 191, 192 and perform highly accurate rate detection.

[0090] 13, in this embodiment, relay device 19 further includes housing 195 (shield portion) that houses wiring board 190. Housing 195 is formed of a conductive material such as metal or conductive plastic having an electromagnetic shielding function, and has a function of protecting wiring board 190 from external noise by being connected to a ground potential. Wiring board 190 is supported by housing 195 via an appropriate support member 196. By configuring relay device 19 as described above, external noise entering wiring board 190 can be more effectively suppressed.

[0091] Incidentally, housing 195 is not limited to a box-like one that shields wiring board 190 from the outside, and the wall surface may be a porous structure such as punched metal or metal mesh, and a predetermined electromagnetic shielding function can be obtained with such a structure. Also, the inner or outer surface of housing 195 may be covered with a radio wave absorber made of a magnetic material or the like, which can further enhance the electromagnetic shielding function.

[0092] [Thickness monitoring device operation] Next, the operation of the film thickness monitoring device equipped with the sensor head 14 configured as above will be described.

[0093] When starting a film formation process by the film formation apparatus 10, the control unit 43 oscillates the piezoelectric vibrator 50 (quartz crystal vibrator 140) of the sensor head 14. At this time, the control unit 43 of the measurement unit 17 inputs a control signal to the switching circuit S of the relay device 19, and the oscillation circuit 41 applies a voltage of a predetermined frequency alternately to the first vibration region 50A (between the first front electrode portion 521 and the first back electrode portion 531) and the second vibration region 50B (between the second front electrode portion 522 and the second back electrode portion 532), and excites the piezoelectric vibrator 50 by the potential difference.

[0094] When the film formation process on the substrate W starts, the shutter 16 is opened, and deposition particles of the film formation material are incident from the deposition source 12 toward the substrate W. At the same time, the deposition particles emitted from the deposition source 12 are incident on the sensor head 14 and adhere to the surface of the piezoelectric vibrator 50 through the opening 82 of the cover member 80 and the hollow portion 61 of the support 60. The deposition particles that have entered the opening 82 are prevented from reaching the second surface electrode portion 522 by the shielding plate 63, so that they adhere only to the first surface electrode portion 521.

[0095] The measurement circuit 42 measures the resonance frequency (hereinafter also referred to as the first resonance frequency) of the piezoelectric vibrator 50 when a voltage of the predetermined frequency is applied between the first front electrode portion 521 and the first back electrode portion 531. The measurement circuit 42 also measures the resonance frequency (hereinafter also referred to as the second resonance frequency) of the piezoelectric vibrator 50 when a voltage of the predetermined frequency is applied between the second front electrode portion 522 and the second back electrode portion 532. Since deposition particles are deposited on the first front electrode portion 521 and deposition particles are not deposited on the second front electrode portion 522, the amount of change in the first resonance frequency due to the deposited mass becomes larger over time than the second resonance frequency.

[0096] On the other hand, during the film formation, the piezoelectric vibrator 50 is subjected to thermal radiation from the deposition source 12. Since the quartz crystal vibrator (vibrator body 51) constituting the piezoelectric vibrator 50 has temperature characteristics, the resonant frequency tends to shift due to temperature drift caused by changes in the amount of heat input. Therefore, the changes in the first and second resonant frequencies include not only those caused by mass changes due to the adhesion of deposition particles, but also frequency changes caused by the temperature characteristics of the piezoelectric vibrator 50 due to thermal radiation from the deposition source 12. In other words, the first resonant frequency includes two changes, namely, the amount of change caused by the deposited mass and the frequency change caused by the temperature characteristics of the piezoelectric vibrator 50 due to thermal radiation, while the change in the second resonant frequency is not caused by the above-mentioned mass change, and the frequency change caused by the temperature characteristics of the piezoelectric vibrator 50 is dominant. In addition, as described above, since the first surface electrode portion 521 and the second surface electrode portion 522 are configured to maintain a geometric similarity relationship to the extent possible, it is considered that the frequency change caused by the temperature characteristics of the piezoelectric vibrator 50 is the same for the first surface electrode portion 521 and the second surface electrode portion 522.

[0097] Therefore, the control unit 43 calculates a first change amount, which is the amount of change per unit time of the first resonance frequency, and a second change amount, which is the amount of change per unit time of the second resonance frequency, and detects the film thickness of the deposit (evaporation film) deposited on the surface of the piezoelectric vibrator 50 from the difference between the first change amount and the second change amount. At this time, since the first change amount and the second change amount are equally affected by the temperature of the piezoelectric vibrator 50, the influence of the temperature is cancelled by taking the difference between the two. As a result, it is possible to calculate only the amount of change in the resonance frequency based on the mass change, and therefore it is possible to detect only the amount of change in the resonance frequency based on the mass change of the piezoelectric vibrator 50 with high accuracy.

[0098] Furthermore, in this embodiment, the first wiring path 191 and the second wiring path 192 in the relay device 19 are formed to be symmetrical to each other, so that by taking the difference between the first change amount and the second change amount, the influence of noise superimposed on the first wiring path 191 and the second wiring path 192 is cancelled. This makes it possible to remove noise from the change amount of the resonant frequency based on the mass change of the piezoelectric vibrator 50, so that the influence of external noise can be suppressed and the resonant frequency of the quartz crystal vibrator can be measured with high accuracy.

[0099] Although the embodiment of the present invention has been described above, the present invention is not limited to the above-mentioned embodiment, and various modifications can be made thereto.

[0100] For example, in the above embodiment, an example has been described in which the sensor device according to the present invention is applied as a film thickness sensor for a vacuum deposition apparatus, but the application is not limited to vacuum deposition apparatuses, and the sensor device can also be applied as a film thickness sensor for other film forming apparatuses such as a sputtering apparatus or a CVD apparatus.

[0101] Furthermore, the sensor head 14 may be provided with a shield layer that covers the area excluding the surface (the deposition surface of the deposition material) of the piezoelectric vibrator 50. In this case, it is possible to suppress intrusion of external noise into the back electrode portion 53 of the piezoelectric vibrator 50, thereby further improving the measurement accuracy.

[0102] In the above embodiment, a film thickness sensor having a single sensor head 14 has been described as an example, but instead, a multi-sensor head having two sensor heads 14 of the same structure may be adopted. This makes it possible to switch to the piezoelectric vibrator of one sensor head when the piezoelectric vibrator of the other sensor head reaches the end of its life due to an increase in the mass of the deposits. The detailed configuration and procedure for switching may be performed using known methods. A common relay device 19 may be used for connection between each piezoelectric vibrator and the measurement unit 17. In this case, in addition to the first and second wiring paths 191, 192 for one piezoelectric vibrator, another set of first and second wiring paths for the other piezoelectric vibrator is formed on the wiring board 190. Similarly, the first and second wiring paths for the other piezoelectric vibrator are formed so as to be symmetrical to each other. In this case, the first and second wiring paths for the other piezoelectric vibrator are also provided with switches having the same structure as the switches S1 and S2. These switches are controlled to open and close based on a control signal input via the terminal unit T7. The terminal units T1 and T2 may be used in common for the first and second wiring paths for one piezoelectric vibrator and the first and second wiring paths for the other piezoelectric vibrator. Therefore, another set of second wiring cables 102 is added, and a total of eight coaxial cables (16 if a current introduction terminal is provided) are used for the one piezoelectric vibrator and the other piezoelectric vibrator.

[0103] Furthermore, the present invention is not limited to a film thickness sensor to which particles adhere in the gas phase, such as for a film forming apparatus, but can also be applied to a sensor device that measures a change in resonance frequency based on the adhesion (or adsorption) of a specific component in a solution (in the liquid phase) to detect the concentration of the component in the solution. Furthermore, the present invention can be applied to detection of minute particles and contaminants. The present invention can also be applied to a sensor device that detects the concentration of a specific gas component in the gas phase. In this case, a SAW element, an FBAR element, or the like can be applied as the piezoelectric vibrator. [Explanation of symbols]

[0104] 10…Film deposition equipment 11…Vacuum chamber 12...evaporation source 14...Sensor head (sensor device) 17…Measuring unit 19...Relay device 20...Film thickness monitoring device (measurement system) 41...Oscillation circuit 42…Measurement circuit 43...Control section 50...Piezoelectric vibrator 51...Transducer body 52…Surface electrode 53…Back electrode 60...Support 61...Hollow part 62…support surface 63…shielding plate 140...Crystal resonator 190...Wiring board 191…First wiring route 192…Second wiring route 194...Copper foil 195…Housing (shield part) 521...first surface electrode portion 522...second surface electrode portion 531...first back electrode portion 532...second back electrode portion

Claims

1. a sensor head including a piezoelectric vibrator having first and second front electrode portions and first and second back electrode portions facing the first and second front electrode portions, respectively, and a shielding plate made of a material that allows heat rays to pass through and that shields the second front electrode portion; a measurement unit that measures a mass of a substance attached to a surface of the piezoelectric transducer by using a correlation between transmission to the piezoelectric transducer and reception from the piezoelectric element, the correlation being obtained by electrically sweeping the vicinity of the resonant frequency of the piezoelectric transducer; a relay device including a first wiring path that electrically connects the first front surface electrode portion and the first back surface electrode portion to the measurement unit, a second wiring path that electrically connects the second front surface electrode portion and the second back surface electrode portion to the measurement unit, and a switching circuit that alternately switches between the first wiring path and the second wiring path, the first wiring path and the second wiring path being formed so as to be symmetrical to each other; A measurement system comprising:

2. The relay device according to claim 1 , the first wiring path, the second wiring path, and the switching circuit are formed on a common wiring substrate; The first wiring path and the second wiring path are formed in a common or symmetrical wiring pattern on the wiring board. Measurement system.

3. 3. The measurement system of claim 2, The wiring board has a shield layer formed of a conductor layer. Measurement system.

4. 3. The measurement system of claim 2, The relay device further includes a shield portion that is made of a material having an electromagnetic shielding function and covers the wiring board. Measurement system.

5. A measurement system according to any one of claims 1 to 4, The measurement unit measures a film thickness or a film formation rate of a substance attached to a surface of the piezoelectric vibrator based on a difference between an amount of change per unit time of a resonance frequency of the piezoelectric vibrator when an AC voltage of a predetermined frequency is applied between the first front electrode portion and the first back electrode portion and an amount of change per unit time of a resonance frequency of the piezoelectric vibrator when the AC voltage is applied between the second front electrode portion and the second back electrode portion. Measurement system.

6. a sensor head including a piezoelectric vibrator having first and second front electrode portions and first and second back electrode portions facing the first and second front electrode portions, respectively, and a shielding plate made of a material that allows heat rays to pass through and that shields the second front electrode portion; A relay device that connects between the piezoelectric transducer and a measurement unit that measures a mass of a substance attached to a surface of the piezoelectric transducer using a correlation between transmission to the piezoelectric transducer and reception from the piezoelectric element, the correlation being obtained by electrically sweeping a frequency range around the resonant frequency of the piezoelectric transducer, a first wiring path that electrically connects the first front surface electrode portion and the first back surface electrode portion to the measurement unit; a second wiring path electrically connecting the second front surface electrode portion and the second back surface electrode portion to the measurement unit; a switching circuit that alternately switches between the first wiring path and the second wiring path; a shielding portion that covers the first wiring path, the second wiring path, and the switching circuit and is made of a material having an electromagnetic shielding function; Equipped with the first wiring path, the second wiring path, and the switching circuit are formed on a common wiring substrate; The first wiring path and the second wiring path are formed in a common or symmetrical wiring pattern on the wiring board. Relay device.

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