JP2003139505A - Sensor head for quartz oscillating type film thickness monitor and monitoring method for film thickness using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sensor head for a quartz oscillating type film thickness monitor having a structure capable of carrying out easy and positive operation, and capable of accurately monitoring the film thickness of a thin film during a film forming process. SOLUTION: The sensor head 11 for the quartz oscillating type film thickness monitor is provided with a stainless steel made quartz plate holder 13 holding quartz plates 12X (121 -1212 ), a PTEF resin made electrode holder 15 holding vane type electrodes 14X (141 -1412 ) for detecting a resonance frequency of the quartz plates 12X (121 -1212 ), a vacuum pulse motor 18 arranged so that a driving shaft is journaled to a rotation center shaft 17 of a rotatable disc 16 comprising the quartz plate holder 13 and the electrode holder 15, a stainless steel made water cooled jacket 19 covering the quartz plate holder 13, the electrode holder 15 and the vacuum pulse motor 18, and a stainless steel made mask 20 with a window 21 covering the quartz plate holder 13 from a film forming direction. It is composed so that the quartz plates 12X (121 -1212 ) can be changed by rotating the quartz plate holder 13 by the vacuum pulse motor 18.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a crystal for monitoring the film thickness of a thin film formed on a crystal resonator by a film forming process such as vacuum deposition or sputtering by measuring the resonance frequency of the crystal resonator. The present invention relates to a sensor head for oscillation type film thickness monitor.

[0002]

2. Description of the Related Art As a method for detecting the thickness of a thin film, there are an optical method, an ion gauge method, a direct current resistance method, a crystal oscillation method and the like. Among these, the crystal oscillation method measures the film thickness of a substance by utilizing the fact that when a substance adheres to the surface of a quartz oscillator, its resonance vibration (sub-vibration, sliding vibration, bending and stretching vibration, etc.) changes. Is. When measuring the film thickness with this product, if a thin film is formed thickly on the crystal unit, the resonance vibration of the crystal unit may become unstable due to peeling of the film or accumulation of internal stress. To become. Therefore, in the crystal oscillation method, it is necessary to determine that the crystal resonator is at the end of its life at this point and switch the used crystal resonator to a new crystal resonator.

Conventionally, a crystal oscillation type film thickness monitor sensor for performing switching is rotationally provided as having a plurality of crystal oscillators so that the crystal oscillators can be switched easily in the film thickness monitor. The head is known. FIG. 1 is a front sectional view of such a rotary crystal oscillation type film thickness monitor sensor head. The film thickness monitor sensor head includes a crystal oscillator mounting desk 2 for mounting the crystal oscillators 1a and 1b. (Crystal resonator holder) and shield cover body 3 (heat shield cover) for the crystal resonators 1a and 1b. Further, the main body 3 is provided with a window 4, and the main body 3 and a portion connected to the main body 3 are fixed, while the crystal unit mounting desk 2 is rotatable. The lower electrodes 5, 6 and 7 are fixed at one point and can be in sliding contact with the electrodes 8 from the crystal unit 1a. In this structure, a substance is formed on the surface of the crystal unit 1a through a window 4 provided in the main body 3, and a thin film having a constant film thickness is formed. At that time, the crystal unit mounting desk 2 is rotated around the rotary shaft 9.
Is rotated to move another crystal oscillator 1b to a position facing the window 4. A cooling water drain pipe 10 is arranged in the main body 3 to suppress the temperature of the entire device.

However, in the above-mentioned conventional crystal oscillation type film thickness monitor sensor head, heat shield and heat sink for the crystal unit are not taken into consideration, and the crystal unit is exposed to radiant heat during the film forming process. As a result, thermal strain may occur, and the resonance frequency of the crystal unit may fluctuate, degrading the performance of the sensor head for film thickness monitoring.

Therefore, the crystal oscillation type film thickness monitor sensor head disclosed in FIG. 8 of Japanese Patent No. 3213613 is
Carousel for mounting a crystal unit (crystal unit holder)
The body and the body are made of a high thermal conductive material, and the heat shield (heat shield cover) is made of a low thermal conductive material to insulate the carousel and the body from the heat generated by vapor deposition. Furthermore, it is good for the body to the carousel. A water-cooled cooling coil (cooling mechanism) is installed to ensure efficient heat transfer, and the heat generated during the vapor deposition process is removed early, and the crystal unit mounted on the carousel (crystal unit holder) is removed. High heat load is prevented.

[0006]

[Problems to be Solved by the Invention] However, originally,
The crystal unit used in the sensor head for film thickness monitoring is
300 in film forming processes such as vacuum deposition and sputtering
May be exposed to high temperature environment above ℃. When the crystal unit in the standby state before use is kept in a relatively low temperature environment such as water cooling as described above, when the crystal unit in use reaches the end of its life, it is switched to a new one. When the crystal unit is used in the environment where it is used, the surrounding environment suddenly changes from a relatively low temperature state to a high temperature state, and as a result, the new crystal unit receives a thermal shock due to the rapid temperature change. Become. Such thermal shock fluctuates the resonance frequency of the crystal unit, which may lead to a decrease in accuracy of the crystal oscillation type film thickness monitor sensor head and a shortened life of the crystal unit.

Further, the above-mentioned sensor head for crystal oscillation type film thickness monitor has a complicated apparatus and has many problems in handling. For example, in this device, a ratchet or the like is used as a rotating means for switching the crystal oscillator, and this is rotationally operated by compressed air. However, such mechanical operation is generally difficult to control, and a large number of pieces are used. When using the crystal oscillator, the positional accuracy becomes strict, and a malfunction may occur when switching the crystal oscillator.

Further, when the film thickness of this thin film is monitored in the film forming process of the multilayer laminated thin film, since the film forming materials forming the multilayer laminated thin film and the internal stress of the crystal oscillator are different, the crystal Detachment occurs between film-forming materials that are laminated in multiple layers on the oscillator, or between the crystal oscillator and the film-forming material that is deposited on this surface. The film thickness may not be accurately monitored.

In view of the above-mentioned problems, the present invention has a structure capable of performing a simple and reliable operation, and is capable of monitoring the film thickness of a thin film during a film forming process with high accuracy. It is an object of the present invention to provide a sensor head for use in a film, and to provide a method for reliably monitoring the film thickness of a thin film using the sensor head for film thickness monitoring.

[0010]

In order to solve the above-mentioned problems, the crystal oscillation type film thickness monitor sensor head of the present invention comprises:
A crystal oscillator holder that holds a plurality of crystal oscillators, an electrode holder that holds an electrode for detecting a resonance frequency of the crystal oscillator, a heat shield cover that covers the crystal oscillator holder and the electrode holder, and a crystal A structure including a rotating mechanism that integrally rotates the oscillator holder and the electrode holder, and a cooling mechanism that cools the crystal oscillator holding holder, the electrode holder, and the rotating mechanism, and uses the crystal oscillator holder and the heat shield cover. A low heat conductive material was used, an electric insulating material was used for the electrode holder, and the crystal unit was rotated by a rotating mechanism to switch the crystal unit. A plurality of crystal oscillators provided in the crystal oscillation type film thickness monitor sensor head configured with such a structure and material are kept within a predetermined temperature range by the heat shield cover and the cooling mechanism even during standby, It is possible to reduce the effect of thermal shock that is applied to the environment of use. Therefore, the crystal oscillator keeps a predetermined resonance frequency, and the film thickness can be monitored with high accuracy by the crystal oscillation type film thickness monitor sensor head using such a crystal oscillator.

In this case, it is preferable to use stainless steel as the low heat conductive material and PTEF resin as the electrical insulating material. Further, by using a water cooling type jacket for the cooling mechanism, the apparatus can be made compact. Becomes Then, by using the vacuum pulse motor for the rotating mechanism, the entire film thickness monitoring device can be arranged in the film forming chamber, and operations such as switching of the crystal oscillator can be reliably performed.

Further, when the above-mentioned crystal oscillation type film thickness monitor sensor head is used, the film forming material used in the film forming step is previously coated on the surface of each crystal resonator on the film forming side by sputtering film formation. Then, when performing film formation using the film forming material, the vacuum pulse motor is operated to switch the crystal oscillator so that the crystal oscillator coated with the same film forming material is selected. By doing so, the film thickness can be monitored for the thin film without forming a multi-layer laminated state, so that peeling between film forming materials cannot occur, and a crystal oscillator with film forming material and this crystal Since the film material strongly adheres to the film material, it is possible to suppress peeling between the crystal unit and the film forming material. Therefore, it becomes possible to reliably monitor the film thickness of the thin film using the above-mentioned crystal oscillation type film thickness monitor sensor head.

[0013]

FIG. 2 is a front sectional view of a crystal oscillation type film thickness monitor sensor head 11 of the present invention. The film thickness monitor sensor head 11 is evenly mounted on the circumference. And a crystal plate holder 13 made of stainless steel, which holds 12 crystal plates 12 _{1 to} 12 ₁₂ (12 _X ), and a crystal plate 1.
Wing-shaped electrode 1 that conducts to each of 2 _{1 to} 12 ₁₂ (12 _X )
4 ₁ ~14 ₁₂ (14 _X) holds a ring-shaped electrode holder 15 made of PTEF resin which is integrally fixed to the quartz plate holder 13, a rotatable circular consisting quartz plate holder 13 and the electrode holder 15. The vacuum pulse motor 18 arranged so that the drive shaft is pivotally attached to the rotation center shaft 17 of the plate 16, the crystal plate holder 13, the electrode holder 15, and the vacuum pulse motor 18 are made of stainless steel and cover as a cooling mechanism. It comprises a water-cooled jacket 19 and a stainless steel mask 20 which covers the crystal plate holder 13 as a heat shield cover from the film forming direction. The mask 20 has crystal plates 12 _{1 to} 12 _12.
A window 21 through which the crystal plate 12 _X to be exposed to the usage environment can be seen is provided, and a film forming material whose film thickness is to be measured is formed on the surface of the crystal plate 12 _X through the window 21 ( Figure 3
reference). Further, since the mask 20 is made of stainless steel and has a heat shielding effect, it is possible to prevent radiant heat generated in the film forming process started thereafter from being conducted to the sensor head 11 for film thickness monitoring, or to prevent the radiant heat from being generated during the film forming process. It also has a role of protecting the film thickness monitoring sensor head 11 from a substance flying in a vacuum.

FIG. 4 is a cross-sectional view of the main part of the rotatable disc 16 composed of the crystal plate holder 13 and the electrode holder 15, which is integrally shown in FIG. Crystal plate 12 ₁ ~
12 _{1 2} (12 _X) disc-shaped crystal plate holder 13 for holding the
And the ring-shaped electrode holder 15 for holding the wing-shaped electrodes 14 _{1 to} 14 ₁₂ (14 _X ) that are electrically connected to the crystal plates 12 _{1 to} 12 ₁₂ (12 _X ) respectively, form a disc 16 integrally, Disk 1
6 is rotatable about a central axis 17.

The wing-shaped electrodes 14 _{1 to} 14 ₁₂ (14 _X ) are wing portions 22 which can be urged against the quartz plates 12 _{1 to} 12 ₁₂ (12 _X ).
_{1 to} 22 ₁₂ (22 _X ) are provided, and the quartz plates 12 _{1 to} 12 ₁₂ and the wing-shaped electrodes 14 _{1 to} 14 ₁₂ are in contact with each other via the wing portions 22 _{1 to} 22 ₁₂ to be in conduction. And the wing-shaped electrodes 14 ₁ to 1
When 4 ₁₂ is pressed against the crystal plates 12 _{1 to} 12 ₁₂ , the wing portions 22 _{1 to} 22 ₁₂ play a role of a cushioning material against this pressure contact. This is because when monitoring the film thickness,
Since the resonance frequency of the crystal plate 12 _X facing the window 21 is measured, the crystal plate 12 _X is adjusted so that it can perform sliding vibration.
This is because it is necessary to secure the degree of freedom of By using such a cushioning material, it is possible to prevent the crystal plate 12 _{X from} being completely fixed.

Further, on the central axis 17 of the disc 16 in FIG.
The drive shaft of the vacuum pulse motor 18 of FIG. 2 is attached to the shaft, and the vacuum pulse motor 18 is driven to drive the crystal plates 12 ₁ to 12 _1.
12 is adapted to rotate integrally with the disc 16.

At this time, the resonance frequencies of the crystal plates 12 _{1 to} 12 ₁₂ mounted on the film thickness monitor sensor head 11 of FIG. 2 are all adjusted to 5 MHz. Further, vane-type electrode 14 _X which conduct the quartz plate 12 _X to be subjected to the environment of use is connected to the oscillator (not shown) via a non-illustrated leaf spring, the quartz plate 12 _X resonant frequency vane-type electrode 14 _It is configured to be detected by the oscillator via _X. Further, as described above, the crystal plate holder 13 and the electrode holder 15 are configured to be integrally rotatable by driving the vacuum pulse motor 18, so that the fluctuation of the resonance frequency of the crystal plate 12 _X is detected. When it is determined that the crystal plate 12 _X has reached the end of its life, the vacuum pulse motor 18 is actuated by the control of a controller (not shown) to rotationally move the disk 16 and face the window 21 of the mask 20. A new crystal plate 12 _Y is moved so that the crystal plate 12 can be switched.

Further, the whole crystal plate 12 on the crystal plate holder 13
After the use of _{1 to} 12 ₁₂ is finished, the fixing screw 23 of the crystal plate holder 13 is removed, and the crystal plate holder 13 is replaced with all the crystal plates 12 _{1 to} 12 ₁₂ . In this way, the crystal plate 12
_{1 to} 12 ₁₂ can be easily replaced.

When monitoring the film thickness of a thin film to be formed using the film thickness monitoring sensor head 11 of FIG. 2, first, the cooling water of a predetermined temperature is circulated in the water cooling jacket 19 through the water cooling pipe 24. Let Baffles 25 and 26 are appropriately arranged in the water-cooled jacket 19 so that the cooling water circulates throughout the jacket 19 so that the inside of the film thickness monitor sensor head 11 can evenly maintain the heat retention effect by the cooling water. I have to. The water-cooled jacket 19 also has a role of ensuring an environment within the temperature limit in which the vacuum pulse motor 18 can operate.

Next, as described above, the water-cooled jacket 19 is used.
With the cooling water circulating inside, start the film formation process and
Crystal plate 12_XStart monitoring the thickness of the thin film deposited on top
It At this time, as described above, the cooling water is the water cooling pipe 24.
Jacket of sensor head 11 for film thickness monitoring
19 to circulate inside the sensor head 11 for film thickness monitoring.
Keeps it warm. Therefore, the film thickness monitor sensor head 1
12 mounted on 1 _XCrystal plate 12 before use other than₁~ 1
Two₁₂Is also kept at a predetermined temperature. Film formation process in this state
Is started, and the crystal plate 12 is passed through the window 21._XThin film on top
Be filmed. And, along with this, the crystal plate 12_XResonance circumference
The wave number fluctuates, and this frequency becomes the wing-shaped electrode 14._XBy electricity
It is detected as a signal.

Further, the operation of the sensor by the sensor head 11 for film thickness monitoring thereafter will be described below with reference to the sensor connection diagram of FIG. In FIG. 5, a film formation controller 27 for controlling the film thickness monitor sensor head 11 is
Deposition chamber system divided by flange 28 (flange 2 in FIG. 5
8 is located outside the area located on the left side of 8).

The cooling water circulates in the jacket 19 of the film thickness monitoring sensor head 11 via the water cooling pipe 24 to keep the inside of the film thickness monitoring sensor head 11 warm as shown in FIG. The resonance frequency of the quartz plate 12 _X detected as an electric signal from the wing-shaped electrode 14 _X shown in FIG.
At, the signal is transmitted via the vacuum internal cable 29 and the auxiliary cable 30, and is detected as an electric frequency by the oscillator 31. Further, the resonance frequency of the crystal plate 12 _X detected by the oscillator 31 is further transmitted to the film formation controller 27 via the vacuum external cable 32.

In the film formation controller 27, the permissible fluctuation range of the resonance frequency of the crystal plates 12 _{1 to} 12 ₁₂ is input in advance, and when the frequency deviating from the permissible range is detected, the crystal plate 12 _X is detected. It is judged that the life has come to an end, and the control signal of the vacuum pulse motor 18 (see FIG. 2) is transmitted to the controller 34 via the pin cable 33. Then, in FIG. 5, according to an instruction from the controller 34,
A control signal is transmitted via the vacuum external control cable 35 and the vacuum internal control cable 36 to operate the vacuum pulse motor 18, and the crystal plate 12 _{X in} FIG. Move to the position where _Y faces window 21. Thus, crystal plate 1
The switching of 2 is completed.

In addition to the simple switching of the crystal plate 12 performed in the present embodiment, there is an efficient film thickness monitoring method using this. That is, when the film-forming process at the time of film thickness monitoring is to form a multilayer laminated thin film using various kinds of film-forming materials, if the quartz plate 12 _X is continuously used to monitor the film thickness, In the high temperature environment of the film forming process, due to the difference in the internal stress between the crystal plate 12 _X and the film forming material or the difference in the internal stress between the film forming materials, the crystal plate 12 _X and the surface thereof are laminated. Peeling may occur between the film forming materials or between the film forming materials. If such peeling occurs, the amount of film formed on the quartz plate 12 _X becomes incomplete, so that the accuracy in monitoring the film thickness decreases. Therefore, in order to prevent this, the surface of each of the crystal plates 12 _{1 to} 12 _{12 on} the film formation side is previously coated with a metal element such as Au, Al, Ni, Cu, Ag, Ti, and Cr by sputtering film formation. It is good to leave.
Quartz plate sputtered particles having energy 12 ₁ to 12
Quartz plate 1 which is driven into the surface of ₁₂ compared to the case of vapor deposition etc.
Adhesion to 2 ₁ to 12 ₁₂ that it has a very good.
Therefore, when the same kind of metal element is laminated on such a coated surface by vapor deposition, the adhesion is improved, so that a more reliable film formation can be obtained as compared with the case where the film is directly formed on the crystal plate 12 _X. . That is, by doing so, the desired operating environment of the sensor head 11 for film thickness monitoring can be maintained, and thereby the film thickness can be monitored with high accuracy.

Further, Ti and A are deposited on the crystal plates 12 _{1 to} 12 _12.
l is sputter-deposited and oxidized or nitrided to obtain T
i / TiN layer or Ti / TiO ₂ layer or Al / A
An IN layer or an Al / Al ₂ O ₃ layer is formed. That is,
In general, even in the case of an oxide film or a nitride film having poor adhesion, the oxide film or the nitride film with the intermediate layer of the metal film strongly adhered to the crystal plate 12 _X is formed in this manner. _{Since the} film is formed on _X , the problem of adhesion is solved.

Each time the process proceeds to a film forming process using another film forming material forming a multi-layer stack, the same kind of material as the film forming material used at that time is previously coated by sputtering film formation. The thickness of each film forming material is monitored by selecting and switching the plates 12 _{1 to} 12 ₁₂ . In this way, without making a multi-layer laminated state,
Since the film thickness is monitored for the film formation on the crystal plate 12 _X , peeling between the film forming materials forming the multilayer stack cannot occur on the crystal plate 12 _X , and When the crystal plates 12 _{1 to} 12 ₁₂ coated with the same kind of material by sputtering film formation in advance are used, the adhesiveness is improved as described above, and the film forming material is removed from the surface of the crystal plate 12 _X. Can be suppressed. Therefore, it is possible to reliably monitor the film thickness using the film thickness monitor sensor head 11.

[0027]

As is apparent from the above description, the crystal oscillation type film thickness monitor sensor head of the present invention has a simple structure, and when this film thickness monitor sensor head is used, it is mounted on the sensor head. Since it is possible to reduce the thermal shock received when the crystal oscillator is subjected to the usage environment, it is possible to accurately monitor the film thickness using such a crystal oscillator. When this film thickness monitor sensor head is used, the film forming material used in the film forming process is previously formed by sputtering film formation, and the surface of each film forming side of the crystal unit mounted on this film thickness monitor sensor head. When a film is formed using the film-forming material, the crystal resonator coated with the same film-forming material should be selected.
If the crystal oscillator is switched by operating the vacuum pulse motor, the film forming material is deposited in close contact with the crystal oscillator, which causes problems such as peeling of the film forming material. Without fail, the film thickness can be reliably monitored.

[Brief description of drawings]

FIG. 1 is a front sectional view of a conventional crystal oscillation type film thickness monitor sensor head.

FIG. 2 is a front sectional view of a crystal oscillation type film thickness monitor sensor head of the present invention.

FIG. 3 is a front view of the film forming direction of FIG.

FIG. 4 is an enlarged sectional view of an essential part of the present invention.

FIG. 5 is a sensor connection diagram of the present invention.

[Explanation of symbols]

11 Crystal Oscillation Type Film Thickness Monitor Sensor Head 12 _X Crystal Plate (Crystal Resonator) 13 Stainless Steel Crystal Plate Holder 14 _X Feather Electrode 15 PTEF Resin Electrode Holder 18 Vacuum Pulse Motor 19 Stainless Steel Water Cooling Jacket

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Toru Okuno             2500 Hagien, Chigasaki-shi, Kanagawa Al             In the back (72) Inventor Atsushi Ito             2500 Hagien, Chigasaki-shi, Kanagawa Al             In the back F term (reference) 2F063 AA16 BA30 BC10 EC03 EC27                       LA04                 4K029 CA01 CA05 EA01

Claims (3)

[Claims] 1. A crystal resonator holder for holding a plurality of crystal resonators, an electrode holder for holding electrodes for detecting a resonance frequency of the crystal resonator, the crystal resonator holder and the electrode holder. A heat shield cover, a rotating mechanism that integrally rotates the crystal oscillator holder and the electrode holder, and a cooling mechanism that cools the crystal oscillator holding holder, the electrode holder, and the rotating mechanism. The crystal oscillator holder and the heat shield cover are made of a low heat conductive material, the electrode holder is made of an electrically insulating material, and the crystal oscillator holder is rotated by the rotating mechanism to switch the crystal oscillator. A crystal oscillation type film thickness monitor sensor head characterized by the following. 2. The low heat conductive material is made of stainless steel, the electrical insulating material is made of PTEF resin, a water cooling jacket is used as the cooling mechanism, and a vacuum pulse motor is used as the rotating mechanism. The crystal oscillation type film thickness monitor sensor head according to claim 1. 3. A method of monitoring a film thickness using the crystal oscillation type film thickness monitoring sensor head, wherein a film-forming material used in a film-forming step is formed in advance by sputtering film-forming for each of the crystal oscillators. On the side surface, then
A method for monitoring a film thickness, characterized in that, when performing film formation using the film forming material, the crystal resonator covered with the film forming material is selected and switched.