JP2008276998A - Film thickness sensor, thin film forming apparatus, organic EL display device manufacturing apparatus, and organic EL display device manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that errors are formed in film thickness measurement values due to temperature changes of quartz oscillator when the film thickness is measured by using the quartz oscillator in a vacuum vessel of a thin film forming device. <P>SOLUTION: As for the constitution of a film thickness sensor 5, a quartz oscillator 11 for the thickness measurement, a housing 13 to hold the quartz oscillator 11, and a holder 20 of water cooling type which holds this housing 13 and cools the quartz oscillator 11 via the housing 13 are equipped. Moreover, oscillation absorbing member 23 having thermal conductivity is inserted between the housing 13 and the holder 20. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a film thickness sensor, a thin film forming apparatus, an organic EL display device manufacturing apparatus, and an organic EL display device manufacturing method.

  2. Description of the Related Art In recent years, attention has been paid to a flat display device using an organic electroluminescent element (organic EL element: EL is an abbreviation for electroluminescence). A display device using organic electroluminescent elements (hereinafter referred to as “organic EL display device”) is a self-luminous display device that does not require a backlight, and thus has advantages such as a wide viewing angle and low power consumption. is doing.

  Generally, an organic electroluminescent element used in an organic EL display device has a structure in which an organic layer made of an organic material is sandwiched between electrodes (anode and cathode) from above and below, and a positive voltage is applied to the anode and a negative voltage is applied to the cathode. By injecting holes into the organic layer from the anode, while injecting electrons from the cathode, holes and electrons are recombined in the organic layer to emit light. .

  The organic layer of the organic electroluminescence device has a plurality of laminated structures including a hole injection layer, a hole transport layer, a light emitting layer, a charge injection layer, and the like. An organic electroluminescent element using a polymer material uses a wet process, but many of the organic electroluminescent elements that have been commercialized in recent years use low molecular weight materials. When forming an organic layer of an organic electroluminescence device using a low molecular weight material, each layer is formed in sequence on the device substrate (usually a glass substrate) of the organic electroluminescence device by vacuum deposition using vacuum thin film formation technology. Thus, a desired laminated structure is obtained. In addition, as an approach to colorization, three types of organic materials corresponding to R (red), G (green), and B (blue) color components are vapor-deposited at different pixel positions to form an organic layer. Yes.

  When an organic layer is formed on an element substrate using a vacuum deposition apparatus, the film thickness needs to be accurately controlled because the characteristics of the organic electroluminescent element are greatly affected by the film thickness of the organic layer. For this reason, the vacuum vapor deposition apparatus is provided with a sensor for measuring the film thickness (hereinafter referred to as “film thickness sensor”). A film thickness sensor using a crystal resonator is known. In this type of film thickness sensor, a film thickness sensor using a crystal resonator is arranged inside a vacuum chamber, and the oscillation frequency of the crystal resonator is determined by the amount of film material adhering to the sensor surface of the film thickness sensor. The mechanism is to measure the film thickness by utilizing the change.

  FIG. 7 is a schematic view showing a configuration example of a conventional thin film forming apparatus (vacuum deposition apparatus) provided with a film thickness sensor using a crystal resonator. As shown in the drawing, in the vacuum chamber 51 of the thin film forming apparatus, a deposition source 52 for evaporating the film material by heating of the heater, and a shutter 54 for blocking the deposition of the film material on the substrate 53 to be processed, A film thickness sensor 55 is provided. The film thickness sensor 55 is configured using a crystal resonator.

  The film thickness information from the film thickness sensor 55 is taken into the film thickness monitor unit 56. The film thickness information obtained by the film thickness sensor 55 is a frequency signal indicating the resonance frequency of the crystal resonator. Therefore, the film thickness monitor unit 56 converts the film thickness information (frequency signal) acquired from the film thickness sensor 55 into a film thickness measurement signal based on the amount of change in the resonance frequency of the crystal resonator, and the film thickness control device 57. To enter. The film thickness control device 57 is configured so that a transformer (heater power source for vapor deposition) 59 is generated based on a film thickness measurement signal input from the film thickness monitor unit 56 so as to meet the film thickness control conditions given in advance from the management terminal 58. Is driven to control the film thickness formed on the substrate 53 to be processed.

  In a film thickness sensor using a crystal resonator, a deviation occurs in a film thickness measurement value due to a temperature change of the crystal resonator. Here, assuming that the oscillation frequency of the crystal resonator = 5 MHz (megahertz) and the temperature of the crystal resonator = 20 ° C., the temperature change of the crystal resonator is ΔT, the film density is ρ, and the temperature change of the crystal resonator is If the deviation amount of the film thickness measurement value is Δd (unit: nanometer: nm), Δd is expressed by the following equation (1).

Δd = 0.255 / ρ × ΔT (1)
The coefficient 0.255 is calculated from the measured value of the temperature change and film thickness change of the crystal resonator with respect to the oscillation frequency change Δf.

  In the above equation (1), for example, when ρ (film density) = 1 and ΔT = 0.1 ° C., Δd = 0.255 / 1 × 0.1 = 0.0255 (nm). For this reason, when the temperature of the crystal unit changes by 0.1 ° C., the measured film thickness shifts by 0.0255 nm (0.255 mm).

  In general, each functional layer of an organic electroluminescent element composed of an organic layer is formed with a film thickness of about 100 nm to several tens of nm, and a host / guest type light emitting layer included therein is formed with a thickness of 50 to 30 nm, for example. The light emitting layer is formed by mixing two materials of host / guest, and depends on the mixed concentration of the guest material and the characteristics of the organic electroluminescence device. For example, the concentration of the light emitting layer is maximum at several percent or less like a coumarin derivative. There are also. When depositing such a guest material, it is necessary to accurately control the thickness of the guest material by deposition at an extremely low rate, so that the film thickness measurement error due to the temperature change of the crystal resonator becomes a value that cannot be ignored. .

  Therefore, conventionally, a technique is known in which the temperature of the crystal unit is controlled to be maintained at a predetermined temperature, thereby suppressing the influence due to the temperature change of the crystal unit (see, for example, Patent Documents 1 to 3). ). However, when this technology is adopted, it is necessary to thoroughly control the temperature of the crystal unit, so that the process management at the actual production site becomes complicated.

  Therefore, as another conventional technique, a technique for correcting a deviation in film thickness measurement due to a temperature change of a crystal resonator is also known (see, for example, Patent Documents 4 and 5).

  FIG. 8 is a cross-sectional view showing a configuration example of a conventional film thickness sensor. In FIG. 8, a plate-like crystal resonator 61 is sandwiched between a pair of metal electrodes 62. The crystal resonator 61 is accommodated in the housing 63. The metal electrode 62 is made of, for example, gold (Au), silver (Ag), aluminum (Al), or an alloy thereof. A crystal oscillator pressing member 64 is provided inside the housing 63. The crystal oscillator pressing member 64 regulates the mounting position of the crystal oscillator 61 by pressing the crystal oscillator 61 against the opening edge of the housing 63 using the elastic force of the spring member 65.

  A terminal member 66 is inserted between the crystal unit 61 and the crystal unit pressing member 64. The terminal member 66 serves as a relay terminal for electrically connecting the electrode terminal 67 and the pair of metal electrodes 62. The electrode terminal 67 is fixed to the housing 63 via an insulator 68. In addition, an insulator 69 that supports the crystal unit 61 and the crystal unit pressing member 64 in the surface direction of the crystal unit 61 is provided inside the housing 63.

  Further, a cooling pipe 70 and a thermocouple 71 are connected to the housing 63. The housing 63 has a flow path (not shown) for flowing cooling water as a cooling medium into the housing structure. One end of the flow path formed in the housing 63 is opened as a cooling water intake port, and the other end of the flow path on the opposite side is opened as a cooling water discharge port. The cooling pipe 70 is connected to a cooling water intake port and a discharge port, respectively. The temperature of the cooling water flowing through the pipe 70 is adjusted to a constant water temperature by a temperature adjusting means (not shown). The thermocouple 71 is provided to correct the temperature characteristics of the crystal unit 61. The signal from the thermocouple 71 is fed back to the signal from the crystal unit 61.

JP-A-63-72872 JP-A-3-261812 JP 2006-78302 A Japanese Patent Laid-Open No. 3-20465 JP-A-3-243766

  However, in the method of cooling the housing 63 holding the crystal unit 61 with the cooling water as described above (the method employed in Patent Document 4), the temperature change of the cooling water changes from the housing 63 to the crystal unit 61. Since it is transmitted quickly, there is a possibility that a change in the water temperature induces an oscillation abnormality of the crystal unit 61. In addition, high-frequency noise generated by the water flow affects the oscillation of the crystal unit 61, and an oscillation abnormality factor is mixed in addition to the temperature. For this reason, resonance or the like due to the water flow in the housing 63 occurs, and there is a risk of inducing oscillation abnormality of the crystal unit 61.

  On the other hand, in the technique described in Patent Document 5, the configuration is complicated because the monitoring vibrator and the temperature compensating vibrator are arranged side by side in the vacuum chamber. In addition, the technique described in Patent Document 5 is based on the premise of vapor deposition of electrode material. However, when limited to vapor deposition of an organic film of an organic EL element, the temperature of the substrate or mask is set to a relatively low temperature. Will keep. For this reason, since the temperature of the crystal unit is controlled around room temperature, an influence due to individual differences between the two units occurs, and high-precision vapor deposition control near room temperature is impossible.

  The reason for managing the crystal unit near room temperature is as follows. That is, one of the manufacturing processes of the organic EL display device is a manufacturing process using a high-precision metal mask. In this manufacturing process, the pixels having a size of about 100 μm are separately coated with a large substrate mask, so that heat to the mask is strictly prohibited. For this reason, the surroundings of the vapor deposition source heated to 300-400 degreeC are cooled, there is almost no heat radiation to a board | substrate and a mask, and it vapor-deposits near room temperature. Therefore, the temperature of the crystal oscillator type film thickness sensor installed in the vicinity of the substrate is inevitably near room temperature.

  A film thickness sensor according to the present invention includes a crystal resonator for film thickness measurement, a housing that holds the crystal resonator, and a water-cooled holder that holds the housing and cools the crystal resonator through the housing. Are provided. Further, the thin film forming apparatus according to the present invention measures a film thickness of a thin film deposited on the substrate to be processed by evaporation of the film material deposited on the substrate to be processed and evaporation of the film material from the deposition source. And a film thickness sensor having the above-described configuration is used as the film thickness sensor.

  In the film thickness sensor and the thin film forming apparatus using the film thickness sensor according to the present invention, the quartz crystal resonator for film thickness measurement is held by the housing, and further this housing is held by the holder, so the holder is cooled by cooling water. In this case, the crystal unit is cooled by the holder through the housing. For this reason, compared with the case where the housing is directly cooled by the cooling water, the temperature change of the cooling water is less likely to appear as the temperature change of the crystal unit.

  According to the present invention, it is possible to suppress the temperature change of the crystal resonator to be smaller than in the case where the housing is directly cooled by the cooling water. For this reason, a deviation (error) in film thickness measurement due to a temperature change of the crystal resonator can be reduced. Therefore, the film thickness can be accurately controlled using the film thickness sensor. As a result, when the present invention is realized as a manufacturing apparatus or manufacturing method of an organic EL display device, an organic layer formed on an element substrate, particularly a guest material of a light emitting layer, is deposited with a very low rate and high accuracy. Is possible.

  Hereinafter, specific embodiments of the present invention will be described in detail with reference to the drawings.

<Configuration of thin film forming apparatus>
FIG. 1 is a schematic view showing a configuration example of a thin film forming apparatus (vacuum deposition apparatus) according to an embodiment of the present invention. As shown in the drawing, in the vacuum chamber 1 of the thin film forming apparatus, a film thickness sensor 5 is provided together with a deposition source 2 for evaporating the film material and a shutter 4 for blocking the deposition of the film material on the substrate 3 to be processed. Is provided.

  The vapor deposition source 2 evaporates the film material by heating the film material filled in a crucible (not shown) by a predetermined heating method (for example, a resistance heating method). The substrate 3 to be processed is arranged in a state facing the vapor deposition source 2 in the vacuum chamber 1. Here, the point type vapor deposition source 2 is adopted, but a long line type evaporation source may be adopted.

  As the substrate to be processed 3, for example, if the thin film forming apparatus forms an organic layer of an organic electroluminescent element, an element substrate (glass substrate or the like) that is a target for forming an organic layer is used. The shutter 4 is arranged so as to shield the substrate to be processed 3 when viewed from the vapor deposition source 2 when blocking the deposition of the film material on the substrate 3 to be processed.

  The film thickness sensor 5 is used to measure the film thickness during film formation on the substrate 3 to be processed, and is configured using a crystal resonator. The film thickness sensor 5 is disposed in the vicinity of the substrate to be processed 3 in the vacuum chamber 1. Further, the sensor surface of the film thickness sensor 5 is disposed at a geometrically equidistant position with respect to the thin film forming surface of the substrate 3 to be processed as viewed from the vapor deposition source 2. Two systems of wiring 6 and cooling piping 7 are connected to the film thickness sensor 5. The wiring 6 and the pipe 7 are led out to the outside of the vacuum chamber 1 through the vacuum introduction port 8.

  FIG. 2 is a cross-sectional view showing a configuration example of the film thickness sensor 5 according to the embodiment of the present invention. In FIG. 2, a plate-like crystal resonator 11 is sandwiched between a pair of metal electrodes 12. The crystal resonator 11 is accommodated in the housing 13. The metal electrode 12 is formed by coating a metal film so as to cover one surface and the other surface of the crystal unit 11. The metal electrode 12 is formed of, for example, gold (Au), silver (Ag), aluminum (Al), or an alloy thereof. The housing 13 is configured using a metal material such as stainless steel (SUS material) or aluminum, and is provided in a state of surrounding the crystal resonator 11.

  The crystal resonator 61 is held by the housing 13. A quartz crystal pressing member 14 is provided inside the housing 13. The crystal oscillator pressing member 14 regulates the mounting position of the crystal oscillator 11 by pressing the crystal oscillator 11 against the opening edge of the housing 13 using the elastic force of the spring member 15. The pressing force of the crystal oscillator pressing member 14 is transmitted to the crystal oscillator 11 via the terminal member 16. The opening 13 </ b> A of the housing 13 is for exposing one surface of the metal electrode 12 of the crystal unit 11, which is a sensor surface of the film thickness sensor 5. A film material evaporated from the vapor deposition source 2 adheres to the sensor surface of the film thickness sensor 5. For this reason, in the vacuum chamber 1, the sensor surface of the film thickness sensor 5 is disposed obliquely downward toward the vapor deposition source 2.

  A terminal member 16 is inserted between the crystal unit 11 and the crystal unit pressing member 14. The terminal member 16 serves as a relay terminal for electrically connecting the electrode terminal 17 and the pair of metal electrodes 12. The electrode terminal 17 is fixed to the housing 13 via an insulator 18. In addition, an insulator 19 that supports the crystal unit 11 and the crystal unit pressing member 14 in the surface direction of the crystal unit 11 is provided inside the housing 13.

  The sensor head of the film thickness sensor 5 is configured by the crystal resonator 61, the metal electrode 12, the housing 13, the crystal resonator pressing member 14, the spring member 15, the terminal member 16, and the insulators 18 and 19 described above.

  A water-cooled holder 20 is provided outside the housing 13 so as to surround the housing 13. A concave portion is formed in the holder 20, and the housing 13 is accommodated in the concave portion. The holder 20 holds the sensor head including the crystal unit 11 and the housing 13. Thereby, the crystal unit 11 is held by the holder 20 via the housing 13.

  The holder 20 preferably has a larger heat capacity than the sensor head, and is configured using a metal material such as stainless steel (SUS material) or aluminum, for example, like the housing 13. Inside the holder 20, a flow path 21 is formed for flowing cooling water serving as a cooling medium. The flow path 21 is formed in a predetermined shape (for example, a zigzag shape) so that the cooling water can be distributed throughout the holder 20. One end of the flow path 21 formed in the housing 13 is opened as a cooling water intake port, and the other end of the flow path 21 on the opposite side is opened as a cooling water discharge port. The cooling pipes 7 (7A, 7B) described above are connected to the cooling water intake port and the discharge port, respectively. The pipe 7 </ b> A is for supplying cooling water to the flow path 21 in the holder 20, and the pipe 7 </ b> B is for discharging cooling water from the flow path 21 in the holder 20. The temperature of the cooling water flowing through the pipe 7 is adjusted to a constant water temperature by a temperature adjusting means (not shown).

  Inside the holder 20, a thermocouple 22 serving as a temperature detecting means is provided. Of the two systems of wiring 6, one system wiring is connected to the thermocouple 22, and the other system wiring is connected to the electrode terminal 17. A thermistor may be used as the temperature detecting means.

  A vibration absorbing member 23 having thermal conductivity is provided at the bottom of the concave portion of the holder 20. The vibration absorbing member 23 is preferably composed of a soft carbon sheet using a carbon material. The vibration absorbing member 23 does not necessarily have to be formed in a sheet shape. However, when the housing 13 and the holder 20 are thermally coupled, the vibration absorbing member 23 is formed in a sheet shape in order to ensure a wide heat transfer area between the two. It is desirable. In addition, it is preferable that the vibration absorbing member 23 is made of a carbon sheet because no outgassing occurs from the vibration absorbing member 23 in a vacuum. The vibration absorbing member 23 is provided with a hole for avoiding positional interference with the electrode terminal 17.

  The vibration absorbing member 23 is inserted between the housing 13 and the holder 20. One surface of the vibration absorbing member 23 is in contact with the housing 13, and the other surface of the vibration absorbing member 23 is in contact with the holder 20. For this reason, the housing 13 is held by the holder 20 via the vibration absorbing member 23 without directly contacting the holder 20. Here, the vibration absorbing member 23 is provided on the back surface of the housing 13 (surface on the electrode terminal 17 side). However, the vibration absorbing member 23 may be additionally set on the side surface of the housing 13 or the like as necessary. .

<Thin film formation method>
When forming a thin film on the substrate 3 to be processed using the thin film forming apparatus having the above-described configuration, the substrate 3 to be formed is transferred into the vacuum chamber 1 by a handling robot, a transfer conveyor, or the like (not shown). Then, the film material is evaporated from the vapor deposition source 2 and scattered upward in the vacuum chamber 1. When the shutter 4 is opened in this state, the film material evaporated from the vapor deposition source 2 adheres to the lower surface of the substrate 3 to be processed. Thereby, a thin film is formed on the lower surface of the substrate 3 to be processed.

<Method for Manufacturing Organic EL Display Device>
Next, a method for manufacturing an organic EL display device when the thin film forming apparatus having the above configuration is used as a manufacturing apparatus for an organic EL display device will be described.

  FIG. 3 is a cross-sectional view showing a configuration example of an organic EL display device to be manufactured in the present invention. First, for example, an anode 26 is formed as a lower electrode on an element substrate 25 for a display device made of a glass substrate or the like. The anode 26 is patterned for each pixel, for example, and is connected to each pixel circuit having a thin film transistor not shown here. Next, an insulating pattern 27 is formed so as to cover the peripheral edge of the anode 26, and pixel separation is performed.

  Next, using the thin film forming apparatus, for example, a hole injection layer 28 and a hole transport layer 29 are sequentially deposited as an organic layer (deposition film) common to all pixels. Next, the red light emitting layer 30r, the green light emitting layer 30g, and the blue light emitting layer 30b are pattern-formed on each pixel on the hole transport layer 29 using the thin film forming apparatus.

  Next, using the thin film forming apparatus, for example, the electron transport layer 31 is deposited as an organic layer (deposited film) common to all pixels. Next, a cathode 32 using a transparent conductive material is sputter-deposited on the electron transport layer 31 as an upper electrode common to all pixels.

  As a result, organic electroluminescent elements of the respective colors formed by sandwiching a multilayer organic layer (deposited film) including the hole injection layer 28 to the electron transport layer 31 between the anode 26 and the cathode 32, that is, the red light emitting element 33r. Thus, the green light emitting element 33g and the blue light emitting element 33b are obtained. Although illustration is omitted here, a sealing film that covers each of the organic electroluminescent elements 33r, 33g, and 33b is further formed, and a sealing substrate made of a light-transmitting material is bonded thereto with an adhesive.

  Thus, an active matrix display device (organic EL display device) 34 in which the light emission of the organic electroluminescent elements 33r, 33g, and 33b of each color is controlled by each pixel circuit connected to each anode 26 is completed. In the display device 34, light generated by the organic electroluminescent elements 33r, 33g, and 33b is extracted from the sealing substrate side through the cathode 32 made of a light transmissive material.

  In the method for manufacturing an organic EL display device described above, an organic layer (hole injection layer 28, hole transport layer 29, light emitting layers 30r, 30g, 30b, electron transport layer 31) is formed on the element substrate 25. In addition, the thin film forming apparatus having the above configuration is used. Specifically, by heating the vapor deposition source 2 to a predetermined temperature (for example, within a range of 300 to 400 ° C.) in the vacuum chamber 1, the organic material to be a film material is evaporated from the vapor deposition source 2, and this organic By depositing the material on the element substrate 25, an organic layer is formed on the element substrate 25.

  At that time, the film thickness sensor 5 using the crystal resonator 11 is arranged in the vacuum chamber 1, the housing 13 holding the crystal resonator 11 is held by the holder 20, and the holder 20 is cooled with cooling water. The film thickness sensor 5 measures the film thickness of the organic film. As a result, the crystal unit 11 is cooled by heat conduction between the housing 13 and the holder 20 serving as the main body of the sensor head. That is, the crystal unit 11 held in the housing 13 is cooled by the holder 20 through the housing 13. For this reason, the temperature of the crystal unit 11 can be managed to the same level as the temperature of the cooling water.

  However, the temperature of the cooling water varies within a preset allowable range. The reason for this is that even if the temperature of the cooling water is adjusted to a constant water temperature by a temperature adjusting means (not shown), strictly speaking, the change in the water temperature cannot be suppressed to zero. This is for managing (controlling). In such a case, if the housing holding the crystal unit is directly cooled with cooling water as in the prior art, the temperature change allowed by the cooling water tends to appear as the temperature change of the crystal unit. For this reason, the measured value of the film thickness sensor fluctuates in synchronization with the temperature change of the cooling water.

  On the other hand, in the film thickness sensor 5 employed in the embodiment of the present invention, the holder 20 that holds the housing 13 is cooled by the cooling water. It takes time until the influence spreads over the entire holder 20 and is transmitted to the housing 13 and the crystal unit 11. For this reason, compared with the case where the housing is directly cooled with cooling water, the sensitivity of the temperature change of the crystal unit 11 to the temperature change of the cooling water is low (dull). Further, if a large heat capacity of the holder 20 is secured, it takes time for the temperature of the holder 20 to reach the temperature of the cooling water even if the temperature of the cooling water changes. For this reason, the temperature change of the holder 20 can be suppressed small. Therefore, even if the temperature of the cooling water changes within an allowable range, the change in the water temperature is less likely to appear as a temperature change in the crystal unit 11. As a result, the temperature change of the crystal unit 11 can be reduced compared to the case where the housing is directly cooled by the cooling water.

  Further, a vibration absorbing member 23 is inserted between the housing 13 and the holder 20, and vibration transmission from the holder 20 to the housing 13 is cut off by the vibration absorbing member 23 in a state where the housing 13 and the holder 20 are thermally coupled. It is a possible configuration. For this reason, it is possible to effectively prevent the resonance abnormality of the crystal unit 11 due to the flow of cooling water or the like.

<Example>
As an example of the present invention, an organic film was deposited under the following film formation conditions, and the relationship between the temperature change of the cooling water and the measured value of the film thickness sensor was examined.
(Deposition conditions)
Cooling water temperature control: 20 ℃ ± 0.1 ℃
Set film thickness rate: 0.02 mm / sec Film material (organic material): C545T (10 (2-Benzothiazolyl)-2,3,6,7-tetrahydro-1,1,7,7,- tetramethyl l-1H, 5H, 11H- [1] benzopyrano [6,7,8-ij] quinolizin-11-one)

  FIG. 4 shows the temperature change of the cooling water used for cooling the crystal unit, where the vertical axis represents the water temperature and the horizontal axis represents the time. As can be seen from the figure, the cooling water temperature of the crystal resonator is controlled at 20 ° C. ± 0.1 ° C. in accordance with the temperature control condition.

  FIG. 5A shows the fluctuation of the film thickness rate when the film thickness is controlled using a conventional film thickness sensor. The vertical axis represents the film thickness rate and the horizontal axis represents the time. FIG. 5B shows the fluctuation of the film thickness rate when the film thickness is controlled using the film thickness sensor of the present invention, where the vertical axis represents the film thickness rate and the horizontal axis represents the time.

  As can be seen by comparing FIGS. 5A and 5B, when the conventional film thickness sensor is used, the measured value of the film thickness sensor increases largely around the set rate in synchronization with the temperature change of the cooling water. It fluctuates (moves up and down), and the fluctuation range is roughly over 0.03 mm. On the other hand, when the film thickness sensor of the present invention is used, the fluctuation of the measurement value of the film thickness sensor is suppressed to be small compared to the conventional one, and the fluctuation width is generally less than 0.01 mm. This result also shows that the film thickness can be controlled with high accuracy by performing the film thickness rate control using the film thickness sensor of the present invention.

  In particular, when the thin film forming apparatus of the present invention is used as an apparatus for manufacturing an organic EL display device, the maximum concentration of the guest material is 1% or less among the organic materials constituting the host / guest light emitting layer. There are materials that exhibit luminescence intensity. For this reason, for example, when it is assumed that the thickness of the light emitting layer is 30 nm and the additive concentration of the guest material is 1%, it is necessary to deposit the guest material at 0.3 nm when forming the light emitting layer. In order to carry out such vapor deposition with high accuracy, it is necessary to form a film with high accuracy at a very low rate. Therefore, it is possible to form a light emitting layer (organic layer) using a thin film forming apparatus equipped with the film thickness sensor of the present invention. It becomes very effective.

  Furthermore, in order to realize more accurate film thickness control, for example, an apparatus configuration as shown in FIG. 6 can be adopted. In FIG. 6, the film thickness information from the film thickness sensor 5 is taken into the film thickness monitor unit 36. The film thickness information obtained by the film thickness sensor 5 is a frequency signal indicating the resonance frequency of the crystal unit 11. For this reason, the film thickness monitor unit 36 converts the film thickness information (frequency signal) acquired from the film thickness sensor 5 into a film thickness measurement signal based on the amount of change in the resonance frequency of the quartz crystal resonator 11. 37.

  The film thickness control device 37 receives temperature information measured using the thermocouple 22 together with a film thickness measurement signal from the film thickness monitor unit 36. In the film thickness sensor 5, the thermocouple 22 is provided in the holder 22, and the crystal resonator 11 is cooled using the holder 22. For this reason, the temperature measured by the thermocouple 22 is substantially proportional to the temperature of the crystal unit 11.

  Therefore, the film thickness control device 37 obtains how much the temperature measured by the thermocouple 22 has changed from a preset target temperature as “temperature change ΔT” and manages it for each deposition material such as film density. The coefficient K is multiplied by the temperature change ΔT, and the multiplied value is obtained as a pseudo film thickness due to the temperature change of the crystal unit 11. Then, the pseudo film thickness is subtracted from the film thickness measurement value measured using the film thickness sensor 5, and the subtraction value is recognized as “true film thickness”. Thereby, the error of the film thickness measurement value accompanying the temperature change of the crystal unit 11 is corrected.

  After obtaining the “true film thickness” in this way, the film thickness control device 37 drives the transformer (heater power source of the vapor deposition source) 39 so as to meet the film thickness control conditions given in advance from the management terminal 38. The film thickness formed on the substrate 3 is controlled by PID control or the like. Thereby, the error of the film thickness measurement value accompanying the temperature change of the crystal unit 11 is corrected, and the film thickness is highly accurately controlled by controlling the heating condition (heater output etc.) of the vapor deposition source 2 based on the correction value. Control can be performed.

  In the above embodiment, the temperature of the holder 20 is measured by the thermocouple 22 on the assumption that (the temperature of the holder 20) = (the temperature of the crystal unit 11). Using a non-contact type thermometer such as a thermometer, the temperature of the crystal surface of the crystal unit 11 is directly measured, or an opening is formed on the back surface (surface on the electrode terminal 17 side) of the housing 13. Or the temperature in the housing 13 may be measured. When such a configuration is adopted, the temperature of the crystal unit 11 can be measured with higher accuracy and better followability, and therefore it is possible to improve the correction accuracy of the film thickness measurement due to the temperature change of the crystal unit 11. Become.

  Moreover, in the said embodiment, although the heating conditions of the vapor deposition source 2 are controlled based on the film thickness measurement value by the film thickness sensor 5, the temperature sensor (not shown) which measures the temperature of the vapor deposition source 2, for example is used. The heating condition of the vapor deposition source 2 is controlled based on the measurement result of the temperature sensor in a certain film formation period, and the heating condition of the vapor deposition source 2 is controlled based on the measurement result of the film thickness sensor 5 in another film formation period. It may be a thing. Moreover, you may control the heating conditions of the vapor deposition source 2 using both the film thickness sensor 5 and a temperature sensor together.

It is the schematic which shows the structural example of the thin film forming apparatus which concerns on embodiment of this invention. It is sectional drawing which shows the structural example of the film thickness sensor which concerns on embodiment of this invention. It is sectional drawing which shows the structural example of the organic electroluminescent display apparatus made into manufacture object by this invention. It is a figure which shows the temperature change of the cooling water used for cooling of a crystal oscillator. It is a figure which shows the fluctuation | variation of the film thickness rate at the time of controlling film thickness using a film thickness sensor. It is the schematic which shows the other apparatus structure which concerns on embodiment of this invention. It is the schematic which shows the structural example of the conventional thin film formation apparatus. It is sectional drawing which shows the structural example of the conventional film thickness sensor.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Vacuum chamber, 2 ... Deposition source, 3 ... Substrate to be processed, 5 ... Film thickness sensor, 11 ... Crystal oscillator, 13 ... Housing, 20 ... Holder, 25 ... Element substrate, 28 ... Hole injection layer, 29 ... Hole transport layer, 30 ... light emitting layer, 31 ... electron transport layer, 34 ... display device

Claims (6)

A crystal unit for film thickness measurement;
A housing for holding the crystal unit;
A film thickness sensor comprising: a water-cooled holder that holds the housing and cools the crystal unit through the housing. The film thickness sensor according to claim 1, wherein a vibration absorbing member having thermal conductivity is inserted between the housing and the holder. The film thickness sensor according to claim 2, wherein the vibration absorbing member is made of a carbon sheet. A deposition source for evaporating the film material deposited on the substrate to be treated;
A film thickness sensor for measuring a film thickness of a thin film deposited on the substrate to be processed by evaporation of the film material from the deposition source;
The film thickness sensor includes: a crystal resonator for measuring a film thickness; a housing that holds the crystal resonator; a water-cooled holder that holds the housing and cools the crystal resonator through the housing; A thin film forming apparatus comprising: A deposition source for evaporating an organic material to be deposited on the element substrate of the organic electroluminescent element;
A film thickness sensor for measuring a film thickness of an organic film deposited on the element substrate by evaporation of the organic material from the deposition source;
The film thickness sensor includes: a crystal resonator for measuring a film thickness; a housing that holds the crystal resonator; a water-cooled holder that holds the housing and cools the crystal resonator through the housing; An apparatus for manufacturing an organic EL display device, comprising: In a method for manufacturing an organic EL display device, the method includes the step of depositing an organic material evaporated from a deposition source in a vacuum chamber on an element substrate to form an organic layer.
A film thickness sensor using a crystal resonator is disposed in the vacuum chamber, a housing for holding the crystal resonator is held by a holder, and the organic film is detected by the film thickness sensor while cooling the holder with cooling water. A method for producing an organic EL display device, comprising: measuring a film thickness of the organic EL display device.

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