Sensor device

Abstract

To stably detect a change in a resonance frequency of a quartz oscillator by restraining an influence of a temperature cycle.SOLUTION: A sensor device includes: a piezoelectric vibrator; an annular support; a connection terminal group; a cover member; and a base member. The piezoelectric vibrator includes: a vibrator body; a front electrode; a rear electrode; and a front electrode terminal section and a rear electrode terminal section formed on the surface of the vibrator body. The support body includes: a hollow section for exposing the front electrode; and a support surface for supporting the periphery of the vibrator body. The connection terminal group includes: a first conductive layer electrically and elastically connected to the front electrode terminal section; and a second conductive layer electrically and elastically connected to the rear electrode terminal section. The cover member has an opening communicating with the hollow section and holds the support. The base member has a first contact connected to the first conductive layer and a second contact connected to the second conductive layer, and is detachably mounted to the cover member while sandwiching the support.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a sensor device that measures the amount of attached material in a vacuum or in the atmosphere from the amount of change in the resonance frequency of a quartz oscillator, and calculates the mass of the attached material, film thickness, film formation rate, etc. [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. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2020-190455 A Summary of the Invention [Problem to be solved by the invention]

[0005] Because the quartz crystal unit is exposed to radiant heat from the evaporation source throughout the deposition process, it is desirable to be able to maintain stable detection accuracy over the long term by suppressing the effects of temperature cycles, which are fluctuations in the heat flux incident on the quartz crystal unit. For this reason, a support structure for the quartz crystal unit that minimizes thermal stress on the quartz crystal unit is required, and it is also necessary to ensure stable electrical conduction between the electrodes formed on the front and back surfaces of the quartz crystal unit and the measurement terminals.

[0006] In view of the above circumstances, an object of the present invention is to provide a sensor device capable of stably detecting changes in the resonant frequency of a quartz crystal resonator while suppressing the effects of temperature cycles. [Means for solving the problem]

[0007] A sensor device according to one aspect of the present invention includes a piezoelectric vibrator, an annular support, a group of connection terminals, a cover member, and a base member. The piezoelectric vibrator has a vibrator body, a surface electrode formed on the surface of the vibrator body to which the object to be detected is attached, a back electrode formed on the back surface of the vibrator body, a surface electrode terminal portion formed on the surface of the vibrator body and connected to the surface electrode, and a back electrode terminal portion formed on the surface of the vibrator body and connected to the back electrode. The annular support has a hollow portion through which the surface electrodes are exposed, and a support surface that supports the peripheral portion of the vibrator body, and is made of an insulating material. The group of connection terminals has a first conductor layer electrically and elastically connected to the surface electrode terminal portion, and a second conductor layer electrically and elastically connected to the back electrode terminal portion, and is disposed between the support surface and the surface of the vibrator body. The cover member has an opening communicating with the hollow portion and holds the support body. The base member has a first contact connected to the first conductor layer and a second contact connected to the second conductor layer, and is removably attached to the cover member with the support therebetween.

[0008] The first conductor layer may have a first metallic land portion formed on the support surface with which the first contactor comes into contact, and a conductive first elastic portion provided between the first land portion and the surface electrode terminal portion. The second conductor layer may have a second metallic land portion formed on the support surface with which the second contactor comes into contact, and a conductive second elastic portion provided between the second land portion and the rear electrode terminal portion.

[0009] The first elastic portion and the second elastic portion may be made of a conductive resin material.

[0010] The surface electrode may have a first surface electrode portion and a second surface electrode portion, and the back electrode may have a first back electrode portion facing the first surface electrode portion across the vibrator body, and a second back electrode portion facing the second surface electrode portion across the vibrator body. The terminal portion for the surface electrode and the first conductor layer may be provided for each of the first surface electrode portion and the second surface electrode portion, and the terminal portion for the back electrode and the second conductor layer may be provided for each of the first back electrode portion and the second back electrode portion, or may be provided in common with the first back electrode portion and the second back electrode portion.

[0011] The support may further have a shielding plate that shields either the first surface electrode portion or the second surface electrode portion from the opening, and the shielding plate may be made of a material that allows the transmission of heat rays entering the opening. Effect of the Invention

[0012] According to the present invention, the influence of temperature cycles can be suppressed and the change in the resonant frequency of the crystal resonator can be stably detected. [Brief description of the drawings]

[0013] [Figure 1] 1 is a schematic cross-sectional view showing a film forming apparatus including a sensor device 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 the above sensor device. [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] 10 is a schematic cross-sectional side view showing a modified example of the configuration of the connection terminal group in the sensor device. FIG. [Figure 11] 10 is a schematic cross-sectional side view showing a modified example of the configuration of the connection terminal group in the sensor device. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In this embodiment, a thickness sensor for a film forming apparatus will be described as an example of the sensor device.

[0015] 1 is a schematic cross-sectional view showing a film formation apparatus including a sensor 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, a basic configuration of the film formation apparatus 10 will be described.

[0016] [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.

[0017] 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.

[0018] 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.

[0019] 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.

[0020] 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.

[0021] 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.

[0022] 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 deposited film on the substrate W are monitored by the measurement unit 17.

[0023] [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.

[0024] 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.

[0025] 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.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] 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.

[0030] [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.

[0031] 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.

[0032] (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.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] The front electrode 52 and the back electrode 53 are not limited to being composed of a single electrode, and may each be composed of a plurality of electrodes. In the piezoelectric vibrator 50 of this embodiment, as shown in Fig. 7, two front electrodes 52 and two back electrodes 53 are arranged on the front and back surfaces of the vibrator body 51.

[0039] 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 symmetrical shapes. 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.

[0040] 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 in a shape symmetrical to the first front electrode portion 521 and the second front electrode portion 522, respectively. 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.

[0041] (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.

[0042] 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.

[0043] 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.

[0044] In this embodiment, the support 60 has a shielding plate 63 that shields 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 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, such as quartz. The shielding plate 63 is not limited to being provided in the hollow portion 62, and may be provided on the support surface 62, for example, or on the upper surface of the support 60 opposite to the support surface 62.

[0045] 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.

[0046] (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.

[0047] 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.

[0048] 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.

[0049] 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.

[0050] 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.

[0051] 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.

[0052] 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.

[0053] 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.

[0054] (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.

[0055] 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.

[0056] 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.

[0057] 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.

[0058] (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).

[0059] 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.

[0060] 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.

[0061] 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.

[0062] 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.

[0063] [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.

[0064] 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 oscillation circuit 41 of the measurement unit 17 alternately applies a voltage of a predetermined frequency between the first front electrode portion 521 and the first back electrode portion 531 and between the second front electrode portion 522 and the second back electrode portion 532, and excites the piezoelectric vibrator 50 by the potential difference.

[0065] 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.

[0066] 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.

[0067] 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.

[0068] 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.

[0069] Furthermore, since the effect of the temperature of the piezoelectric vibrator 50 is cancelled by taking the difference between the first change amount and the second change amount, it is possible to detect only the change amount of the resonance frequency based on the change in 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.

[0070] [Sensor head function] Here, since the piezoelectric vibrator 50 is exposed to radiant heat from the deposition source 12 throughout the film formation, it is desirable to be able to maintain stable detection accuracy over a long period of time by suppressing the effects of temperature cycles, which are fluctuations in the heat flux incident on the piezoelectric vibrator 50. For this reason, a support structure for the piezoelectric vibrator 50 that minimizes thermal stress applied to the piezoelectric vibrator 50 is required, and it is also necessary to ensure stable electrical conduction between the electrodes formed on the front and back surfaces of the piezoelectric vibrator 50 and the measurement terminals.

[0071] In this embodiment, the front electrode terminal portion 520 and the back electrode terminal portion 530 of the piezoelectric vibrator 50 are electrically and elastically connected to the support surface 62 of the support 60 via the connection terminal group 70, so that the piezoelectric vibrator 50 can vibrate without being subjected to a restraining force from the support 60, and even if the piezoelectric vibrator 50 undergoes thermal expansion due to a fluctuation in the heat flux incident on the piezoelectric vibrator 50, the piezoelectric vibrator 50 is not affected by thermal stress, so that oscillation at a stable resonance frequency can be ensured. This makes it possible to detect changes in the deposition amount of vapor deposition particles on the piezoelectric vibrator 50 with high accuracy, thereby realizing a desired film formation rate and stable film thickness measurement.

[0072] Furthermore, according to this embodiment, the multiple contacts 92 connected to the measurement unit 17 are connected to the first and second land parts 711, 721 constituting the connection terminal group 70. In other words, since each contact 92 is connected to the first and second land parts 711, 712, which are stationary systems, rather than to the piezoelectric vibrator 50, which vibrates dynamically, a stable electrical connection can be maintained. Therefore, a stable electrical conduction between the piezoelectric vibrator 50 and the contacts 92 can be ensured.

[0073] Furthermore, according to this embodiment, the support 60 and the base member 90 that support the piezoelectric vibrator 50 are configured to be detachable from the cover member 80 via the retaining pin 84, which facilitates the replacement of the piezoelectric vibrator 50. Also, since each contactor 92 is biased by the spring member 95, when the base member 90 is attached to the cover member 80, the contactors 92 can be brought into contact with the first and second land portions 711, 712 with a desired contact pressure, regardless of the size or configuration of the piezoelectric vibrator 50.

[0074] Naturally, in order to reduce the binding force, it is desirable that each contactor 92 has a probe pin shape, 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 will not be bound (small slippage can be expected) even if thermal expansion occurs in the support body 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.

[0075] 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.

[0076] [Other examples of elastic part configurations] Next, the first and second elastic portions 712, 722 constituting the connection terminal group 70 will be described in detail.

[0077] The first and second elastic parts 712, 722 are provided between the first and second land parts 711, 721 and the front electrode and back electrode terminal parts 520, 530, and electrically and elastically connect them. As described above, the first and second elastic parts 712, 722 are made of a conductive resin material, a metal coil, a leaf spring, steel wool, or the like.

[0078] In addition to the above, the elastic parts 712, 722 may be configured by a combination of elastic bodies E1, E2 and a rigid body G1 disposed between the elastic bodies E1, E2 as shown in Fig. 10. In this case, the first and second elastic parts 712, 722 function as links, thereby increasing the allowable displacement of the piezoelectric vibration body 50.

[0079] Fig. 11 is a schematic side cross-sectional view showing one embodiment of the configuration of Fig. 10. In this example, the first and second elastic bodies 712, 722 have metallic rigid parts 712a, 722a and conductive resin elastic layer parts 712b, 722b that cover the rigid parts 712a, 722a. The elastic layer part 712b is integrally joined to the first land part 711 and the front electrode terminal part 520, and the elastic layer part 722b is integrally joined to the second land part 721 and the back electrode terminal part 530.

[0080] The resonant frequencies of the first and second elastic parts 712, 722 are adjusted to be different from the resonant frequency of the piezoelectric vibrator 50. This makes it possible to detect the resonant frequency of the piezoelectric vibrator 50 and its change over time with high accuracy. For example, when the resonant frequency of the piezoelectric vibrator 50 is 15 MHz, the resonant frequencies of the first and second elastic parts 712, 722 are designed to be frequencies separated by 15 MHz±200 kHz or more.

[0081] 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, as a matter of course.

[0082] 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.

[0083] In addition, in the above embodiments, the surface electrode 52 and the back electrode 53 of the piezoelectric vibrator 50 are each divided into two electrode portions (first and second surface electrode portions 521, 522, first and second back electrode portions 531, 532), but this is not limited to this, and the present invention can also be applied to piezoelectric vibrators each composed of a single electrode portion.

[0084] 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.

[0085] Furthermore, in the above embodiment, the fitting portion 64 into which the retaining pin 83 fits is formed on the outer circumferential surface of the support 60, but the formation of the fitting portion 64 may be omitted. In this case, the restraining force of the retaining pin 83 on the support 60 is reduced, so that the thermal stress acting on the support 60 can be alleviated. [Explanation of symbols]

[0086] 10…Film deposition equipment 11…Vacuum chamber 12...evaporation source 14...Sensor head (sensor device) 17…Measuring unit 20...Film thickness monitor 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 70...Connection terminals 71...first conductor layer 72...Second conductor layer 80...Cover member 81…Storage section 82…Opening 83…Retaining pin 90...Base material 92...Contact 140...Crystal resonator 520…Terminal section for surface electrode 521...first surface electrode portion 522...second surface electrode portion 530...Terminal section for back electrode 531...first back electrode portion 532...second back electrode portion 711…First Land Section 712...First elastic portion 721…Second Land Section 722...Second elastic portion 921…First contact 922…Second contact

Claims

1. a piezoelectric vibrator having a vibrator body, a surface electrode formed on the surface of the vibrator body to which a detection target substance adheres, a back electrode formed on the back surface of the vibrator body, a surface electrode terminal portion formed on the surface of the vibrator body and connected to the surface electrode, and a back electrode terminal portion formed on the surface of the vibrator body and connected to the back electrode; a ring-shaped support member made of an insulating material, the ring-shaped support member having a hollow portion through which the surface electrodes are exposed and a support surface for supporting a peripheral portion of the vibrator body; a connection terminal group including a first conductor layer electrically and elastically connected to the front surface electrode terminal portion and a second conductor layer electrically and elastically connected to the back surface electrode terminal portion, the connection terminal group being disposed between the support surface and a front surface of the vibrator body; a cover member having a housing portion that houses the support body and an opening portion that communicates with the hollow portion of the support body housed in the housing portion; a base member having a first contact connected to the first conductor layer and a second contact connected to the second conductor layer, the base member being detachably attached to the cover member with the support therebetween; A sensor device comprising:

2. The sensor device according to claim 1 , the first conductor layer has a first land portion made of metal that is formed on the support surface and that is in contact with the first contact, and a first conductive elastic portion that is provided between the first land portion and the front surface electrode terminal portion; The second conductor layer has a second land portion made of metal that is formed on the support surface and that is in contact with the second contact, and a conductive second elastic portion that is provided between the second land portion and the rear electrode terminal portion. Sensor device.

3. The sensor device according to claim 2, The first elastic portion and the second elastic portion are made of a conductive resin material. Sensor device.

4. The sensor device according to claim 1 , the surface electrode has a first surface electrode portion and a second surface electrode portion, the back surface electrode has a first back surface electrode portion facing the first front surface electrode portion across the vibrator body, and a second back surface electrode portion facing the second front surface electrode portion across the vibrator body, the surface electrode terminal portion and the first conductor layer are provided for each of the first surface electrode portion and the second surface electrode portion, The rear surface electrode terminal portion and the second conductor layer are provided for each of the first rear surface electrode portion and the second rear surface electrode portion, or are provided in common with the first rear surface electrode portion and the second rear surface electrode portion. Sensor device.

5. The sensor device according to claim 4, the support further includes a shielding plate that shields either the first surface electrode portion or the second surface electrode portion from the opening, The shielding plate is made of a material that allows the transmission of heat rays incident on the opening. Sensor device.

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