JP2006283086A - Vacuum deposition method and vacuum deposition apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optimal vacuum deposition method for precisely and stably forming a film with a predetermined film thickness by grasping a vaporizing state of a film-forming material while the film is formed by vacuum deposition and adjusting an vaporizing rate of the film-forming material on the basis of the grasped result, and to provide a vacuum deposition apparatus for conducting the vacuum deposition method. <P>SOLUTION: The vacuum deposition method is directed at forming the film on a substrate by reducing a pressure inside a vacuum chamber, passing a current to an evaporation vessel for resistance-heating and accommodating the film-forming material to heat it, and comprises the steps of: keeping the control of heating for the evaporation vessel for a predetermined period of time (steps A to B) when resistance-heating the film-forming material so that the vaporizing rate of the film-forming material from the evaporation vessel becomes a predetermined value; and then, changing the heating condition for the evaporation vessel into a constant heating condition (steps C to D). The apparatus has a structure for realizing the method. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention belongs to the technical field of vacuum deposition, and particularly relates to a vacuum deposition method and a vacuum deposition apparatus that can control a deposition rate with high accuracy.

  When irradiated with radiation (X-rays, α-rays, β-rays, γ-rays, electron beams, ultraviolet rays, etc.), a part of this radiation energy is accumulated, and then irradiated with excitation light such as visible light, A phosphor exhibiting stimulated emission according to the stored energy is known. This phosphor is called a storage phosphor (stimulable phosphor) and is used for various applications such as medical applications.

As an example, a radiographic image using a sheet (hereinafter referred to as a phosphor sheet (also referred to as a radiation image conversion sheet)) having a layer containing the stimulable phosphor (hereinafter referred to as a phosphor layer). An information recording / reproducing system is known and has been put into practical use, for example, as FCR (Fuji Computed Radiography, trade name of Fuji Photo Film Co., Ltd.).
In this system, radiation image information of a subject such as a human body is recorded on a phosphor sheet (the phosphor layer), and after recording, the phosphor sheet is irradiated with excitation light to generate stimulated emission light. An image signal is obtained by photoelectrically reading the exhaust light, and an image reproduced based on this image signal is output as a radiation image of the subject to a display device such as an LCD or CRT, or a recording material such as a photographic material. To do.

Such a phosphor sheet is usually prepared by dispersing a stimulable phosphor powder in a solvent containing a binder and the like, and applying the paint to a sheet-like support made of glass or resin. It is produced by drying.
On the other hand, as shown in Patent Document 1 and Patent Document 2, a phosphor sheet in which a phosphor layer is formed on a support by a physical vapor deposition method (vapor deposition method) such as vacuum vapor deposition is also known. ing. Since the phosphor layer produced by vapor deposition is formed in a vacuum, there are few impurities, and since there are almost no components other than the storage phosphor such as a binder, there is little variation in performance, and the luminous efficiency is low. It has excellent properties of being very good.

  Further, as a vacuum vapor deposition method capable of forming a phosphor layer having a good columnar crystal structure capable of obtaining high photostimulable light emission characteristics and image sharpness, a comparison of about 1 to 10 Pa while introducing an inert gas. There is known a method of performing vapor deposition with a low degree of vacuum (see Patent Document 3, etc.).

Here, in the film formation by vacuum deposition, in order to stably form an appropriate film having a predetermined film thickness, the evaporation amount (evaporation rate) of the film forming material from the crucible, that is, the evaporation rate control is controlled. It is important to do properly.
Particularly, in the phosphor sheet as described above, the thickness of the phosphor layer is usually about 500 μm, and when it is thick, it may exceed 1000 μm. In addition, in medical applications such as the above-mentioned FCR, if the film thickness is not appropriate, the distance between the sensor that reads the photostimulated luminescence and the phosphor layer surface becomes inappropriate, and image quality degradation such as blurring of the image is caused. Cause. Such image quality degradation may cause misdiagnosis. Therefore, when manufacturing a phosphor sheet by forming a phosphor layer by vacuum deposition, it is necessary to control the deposition rate with high accuracy.

Conventionally, as a method for controlling the amount of evaporation in vacuum deposition, a quartz crystal monitor is used to directly measure the amount of evaporation of the film forming material, feed back the measurement results, and control the heating by the heating source to control the amount of evaporation. A method of controlling is known.
In addition, there is also known a method of controlling the evaporation amount by measuring the temperature, feeding back the measurement result, and controlling the heating by the heating evaporation source (see Patent Document 4).

Japanese Patent No. 2789194 JP-A-5-249299 US Patent US2001 / 0010831A1 Specification JP 2003-13207 A

  In Patent Document 4, feedback control based on the temperature measurement result is performed. However, in the feedback control based on temperature, when the amount of material in the container decreases, the correlation between the measured value and the evaporation rate becomes weak. I found out that there was a problem.

  An object of the present invention is to solve the above-described problems of the prior art, and in the film formation by vacuum evaporation, grasp the evaporation state of the film formation material and adjust the evaporation rate of the film formation material based on this. A film having a predetermined thickness can be stably formed with high accuracy. For example, a vacuum deposition method optimal for manufacturing a stimulable phosphor sheet for forming a phosphor layer by vacuum deposition and the vacuum deposition method are provided. An object of the present invention is to provide a vacuum deposition apparatus to be implemented.

  In order to achieve the above object, the vacuum deposition method according to the present invention forms a film on a substrate by depressurizing the inside of the vacuum chamber and energizing and heating a resistance heating evaporation container containing a film forming material. When performing the vacuum evaporation, the heating condition of the evaporation container is controlled for a predetermined time so that the value indicating the evaporation state of the film forming material from the evaporation container becomes a predetermined value, and then the evaporation container is heated. It is characterized by switching to be performed under a constant heating condition.

In the vacuum vapor deposition method according to the present invention, after the vapor deposition is started, the heating condition is controlled for a predetermined time, and then the heating is performed so that the evaporation container is heated while maintaining the heating condition when the predetermined time has elapsed. Is preferred.
The predetermined time referred to here may be, for example, a time until a value indicating the evaporation state is maintained within a predetermined range (variation rate 1%) for a predetermined time (such as 3 minutes). Alternatively, it may be a predetermined time (2 hours or the like) in anticipation of the time until the above-described maintenance is performed.

Further, in the vacuum vapor deposition method according to the present invention, after the heating condition is controlled for a predetermined time before the vapor deposition starts, the evaporation container is heated while maintaining the heating condition when the predetermined time has elapsed. After that, it is preferable to start vapor deposition.
Here, the vapor deposition does not need to be started immediately after the switching described above, and may be performed after an arbitrary time has elapsed since the switching.

In the vacuum vapor deposition method according to the present invention, the value indicating the evaporation state is a temperature of a film forming material in the evaporation container, a temperature of the evaporation container, or above the evaporation container. The temperature of the evaporating stream is preferred.
Further, the value indicating the evaporation state is an evaporation rate measured by a sensor using a crystal resonator, or a time change amount of a deposited film thickness measured by a displacement measuring device using a laser. It is preferable.

Moreover, in the vacuum evaporation method which concerns on this invention, it is preferable that the said heating conditions are based on an electric current, are based on a voltage, or are based on electric power.
In the vacuum deposition method according to the present invention, when a plurality of the evaporation containers are provided, the switching time may be the same for all of these evaporation containers, or the switching time may be set for each of the evaporation containers. It may be determined individually.

  On the other hand, a vacuum evaporation apparatus according to the present invention includes a vacuum chamber, an exhaust means for exhausting the inside of the vacuum chamber, a substrate holding means for holding a substrate on which a film forming material is to be deposited, an evaporation container for resistance heating, A vacuum heating apparatus comprising: a resistance heating power source for supplying resistance heating power to the evaporation container; and a control means for driving the resistance heating power source to control the heating of the evaporation container. A control switching function for switching the heating of the evaporation container to a predetermined value after the control of the heating condition of the evaporation container for a predetermined time so that the value indicating the evaporation state of the film material becomes a predetermined value; It is characterized by that.

  Here, the control switching function preferably gives priority to a switching instruction from an operator. Moreover, it is preferable that the said board | substrate holding means is what conveys the said board | substrate linearly in a predetermined direction by a linear conveyance path | route.

  According to the present invention having the above-described configuration, when performing vacuum deposition by resistance heating, the evaporation container is heated so that the evaporation rate of the film forming material from the evaporation container becomes a predetermined value for a while from the start of deposition. The control is continued for a predetermined time, and then the heating of the evaporation container is switched to a constant heating condition based on the preferred control condition found in the above-described control process. Therefore, it is possible to stably form an appropriate film having a predetermined film thickness.

  Therefore, for example, by using the present invention for manufacturing a stimulable phosphor sheet for forming a phosphor layer by vacuum deposition, a high-quality phosphor layer with an accurate film thickness can be formed. It is possible to stably manufacture a high-quality stimulable phosphor sheet that is free from image quality degradation due to errors.

Hereinafter, a vacuum deposition method and a vacuum deposition apparatus according to the present invention will be described in detail based on preferred embodiments shown in the accompanying drawings.
Here, as an example, the temperature is measured inside an evaporation vessel (crucible) serving as a resistance heating source, and the crucible heating, that is, the evaporation amount (= deposition rate) of the film forming material is controlled according to the result. Shall. Thereby, the temperature of the film-forming material can be measured stably and appropriately, and appropriate control can be performed.

In FIG. 1, the conceptual diagram of an example of the fluorescent substance sheet manufacturing apparatus using the vacuum evaporation method which concerns on one Embodiment of this invention is shown. 1A is a front view, and FIG. 1B is a side view.
A phosphor sheet manufacturing apparatus (hereinafter referred to as manufacturing apparatus) 10 shown in FIG. 1 includes a film forming material (evaporation source) to be a phosphor (matrix), and a film forming material to be an activator (activator). Is a device for producing a (storable) phosphor sheet by forming a layer made of a stimulable phosphor (hereinafter referred to as a phosphor layer) on the surface of the substrate S by binary vacuum vapor deposition that evaporates separately. .

Such a manufacturing apparatus 10 basically includes a vacuum chamber 12, a substrate holding / conveying mechanism 14, a heating evaporation unit 16, and a gas introduction nozzle 18.
In addition, it goes without saying that the manufacturing apparatus 10 may include various constituent elements of a known vacuum deposition apparatus such as a plasma generator (ion gun) as necessary. That is.

In the illustrated example, as a preferred example, cesium bromide (CsBr) as a phosphor component and europium bromide (EuBr _x (x is usually 2 to 3) as an activator component, Is preferably used as a film-forming material, and binary vacuum deposition is performed by resistance heating to form a phosphor layer made of CsBr: Eu, which is a storage phosphor, on the substrate S, and a phosphor sheet is formed. Make it. Therefore, an evaporation container (hereinafter referred to as a crucible) 50 serving as a resistance heating source for the phosphor and a crucible 52 serving as a resistance heating source for the activator are disposed in the heating evaporation unit 16.

  Here, in order to simplify the drawing and clarify the configuration, although not shown, a resistance heating power source for resistance heating is connected to each crucible 52. For the same reason, only one location is shown in FIG. 1A and illustration is omitted in FIG. 1B, but each crucible 50 is provided with a thermocouple 58, which will be described later, as a temperature measuring means. Furthermore, the resistance heating power source 20 and the heating control means 22 are connected.

  In addition, the manufacturing apparatus 10 according to the present embodiment includes a gas introduction nozzle 18 that introduces an inert gas during film formation. Preferably, the vacuum chamber 12 is once evacuated to a high degree of vacuum and then evacuated. An inert gas such as argon is introduced from the gas introduction nozzle 18 while performing a vacuum degree of 0.1 to 10 Pa (particularly 0.5 to 3 Pa) in the vacuum chamber 12 (hereinafter referred to as a medium vacuum), Under this vacuum, the phosphor layer is formed.

That is, the film-forming material (cesium bromide and europium bromide) is heated and evaporated by resistance heating in the heating evaporation unit 16, and the substrate S is conveyed linearly (hereinafter referred to as linear conveyance) by the substrate holding and conveying mechanism 14. Then, the phosphor layer is formed on the substrate S by vacuum deposition.
By forming the phosphor layer under a vacuum in which gas is introduced, the phosphor layer has a good columnar crystal structure, and a phosphor sheet having excellent image sharpness and stimulated emission characteristics is manufactured. can do.

In the present invention, as the stimulable phosphor (stimulable phosphor) forming the phosphor layer, various materials other than CsBr: Eu can be used. As an example, an alkali halide storage phosphor represented by the general formula “M ^I X · aM ^II X ′ ₂ · bM ^III X ″ ₃ : cA” disclosed in JP-A-57-148285 is preferred. Illustrated.

In the above formula, M ^I is at least one selected from the group consisting of Li, Na, K, Rb and Cs, and M ^II is Be, Mg, Ca, Sr, Ba, Zn, Cd, Cu and Ni. And M ^III is Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm. , Yb, Lu, Al, Ga and In, at least one trivalent metal selected from the group consisting of F, Cl, Br and I. A is composed of Eu, Tb, Ce, Tm, Dy, Pr, Ho, Nd, Yb, Er, Gd, Lu, Sm, Y, Tl, Na, Ag, Cu, Bi, and Mg. It is at least one selected from the group. Further, 0 ≦ a <0.5, 0 ≦ b <0.5, and 0 ≦ c <0.2.

  In addition, U.S. Pat. No. 3,859,527, JP-A-55-12142, 55-12144, 55-12145, 57-148285, 56-116777. No. 5, 58-69281, 59-75200, and the like are also preferred.

In particular, the alkali halide storage phosphor is preferably exemplified in terms of photostimulable light emission characteristics, sharpness of a reproduced image, and the effect of the present invention can be suitably expressed. Especially, M ^I is at least Cs. An alkali halide storage phosphor in which X contains at least Br and A is Eu or Bi is preferable, and among these, “CsBr: Eu” is particularly preferable.

  The substrate S is not particularly limited, and various sheet-like substrates used in phosphor sheets, such as glass, ceramics, carbon, aluminum, PET (polyethylene terephthalate), PEN (polyethylene naphthalate), and polyimide, All are usable, and there is no particular limitation on the shape.

The vacuum chamber 12 is a known vacuum chamber (bell jar, vacuum chamber) that is formed of iron, stainless steel, aluminum, or the like and is used in a vacuum deposition apparatus.
The gas introduction nozzle 18 is also a well-known gas introduction means used in a vacuum vapor deposition apparatus, a sputtering apparatus, etc., having a connection means with a cylinder or the like, a gas flow rate adjusting means, or the like (or connected thereto). In addition, an inert gas such as argon gas or nitrogen gas is introduced into the vacuum chamber 12 in order to form a phosphor layer by vacuum deposition in the medium vacuum.

A vacuum pump (not shown) is connected to the vacuum chamber 12.
The vacuum pump is not particularly limited, and various types of vacuum pumps that can be used as long as the required ultimate vacuum can be achieved can be used. As an example, an oil diffusion pump, a cryopump, a turbomolecular pump or the like may be used, and a cryocoil or the like may be used in combination as an auxiliary. In addition, in the manufacturing apparatus 10 which forms the above-mentioned phosphor layer, the ultimate vacuum in the vacuum chamber 12 is preferably 8.0 × 10 ⁻⁴ Pa or less.

The substrate holding and transporting mechanism 14 holds the substrate S and transports the substrate S along a linear transport path (hereinafter referred to as linear transport), and includes a substrate holding unit 30 and a transport unit 32. The
The conveying means 32 has a linear motor guide having a guide rail 34 and an engaging member 36 guided by the guide rail, a ball screw composed of a screw shaft 40 and a nut 42, a rotational drive source 44 of the screw shaft 40, etc. This is a known linear moving mechanism to be used.

  On the other hand, the substrate holding means 30 has an engagement member 48 that engages with the nut 42 of the ball screw and the engagement member 36 of the linear motor guide, and holds the substrate S at the lower end portion. And is linearly moved in a predetermined direction (the left-right direction in FIG. 1A and the direction perpendicular to the paper surface in FIG. 1B) by the conveying means 32.

  In the manufacturing apparatus 10 of the illustrated example, the substrate S is conveyed linearly in the predetermined direction by conveying the substrate holding means 30 by the conveying means 32 while the substrate S is held by the substrate holding means 30. In the illustrated example, the substrate S is transported in a straight line, and a plurality of evaporation sources are arranged in the transport orthogonal direction, thereby forming a phosphor layer with high film thickness distribution uniformity. .

  In general, as the film thickness is the same, the greater the number of passes through the upper portion of the heating evaporation unit 16, the higher the film thickness distribution uniformity. Therefore, the phosphor layer is reciprocated several times. Is preferably formed. In addition, the number of reciprocations may be appropriately determined according to the target film thickness of the phosphor layer, the target film thickness distribution uniformity, and the like. The conveyance speed may be appropriately determined according to the conveyance speed limit of the apparatus, the number of reciprocations, the target phosphor layer thickness, and the like.

A heating evaporation unit 16 is disposed below the vacuum chamber 12.
The heating evaporation unit 16 is a part that evaporates cesium bromide and europium bromide, which are film forming materials, by resistance heating. Although not shown for the same reason as above, a shutter that shields the vapor of the film forming material from the heating evaporation unit 16 (the crucible 50 and the crucible 52) is disposed on the heating evaporation unit 16.

  As described above, as a preferred embodiment, the manufacturing apparatus 10 performs binary vacuum deposition in which cesium bromide as a phosphor component and europium bromide as an activator component are independently heated and evaporated. Is. Accordingly, the heating evaporation unit 16 includes the crucible 50 for cesium bromide (for phosphor) and the crucible 52 for europium bromide (for activator).

  As shown in the schematic top view of FIG. 2, in the illustrated manufacturing apparatus 10, the number of the crucibles 50 and the crucibles 52 is six in a direction orthogonal to the transport direction of the substrate S (hereinafter simply referred to as the transport direction). Are arranged. Note that the crucibles are insulated from each other due to separation, insertion of an insulating material, or the like.

  Further, both the crucible 50 and the crucible 52 have two rows of crucibles, and the rows of crucibles 50 are arranged so as to sandwich the two crucible 52 rows in the transport direction. Further, the crucibles 50 and crucibles 52 that are adjacent to each other in the transport direction are arranged so as to coincide with the arrangement direction of the rows to form a pair, and the crucibles 50 and the crucibles 52 of different rows are staggered in the arrangement direction. Arranged so as to fill the gaps in the same direction. This makes it possible to discharge steam uniformly in the arrangement direction.

  In the manufacturing apparatus 10 of the illustrated example, the entire surface of the substrate S is formed by linearly transporting the substrate S and arranging the resistance heating evaporation crucibles 50 and 52 in a direction perpendicular to the transport direction, as described above. Uniform exposure with the vapor of the film material enables formation of a phosphor layer with extremely high film thickness distribution uniformity.

  That is, the phosphor layer is formed by vacuum deposition while the substrate S is conveyed linearly, so that the moving speed on the surface of the substrate S (non-deposition surface) is made uniform over the entire surface, and a plurality of crucibles (resistance heating evaporation sources) ) Are arranged in a straight line in the direction perpendicular to the transport direction, and the vapor deposition of the film forming material can be uniformly exposed on the entire surface of the substrate S with an extremely simple evaporation source arrangement, and the film thickness distribution is uniform. A highly fluorescent layer can be formed. In particular, in the medium-vacuum vacuum deposition as described above, there is a collision between the gas particles such as argon and the evaporated film forming material, so that the distance between the substrate and the crucible is larger than that in the ordinary high-vacuum deposition. Therefore, since the film-forming material reaches the substrate S before diffusing into the system, the effect is great.

  In addition, by having such a configuration, the activator component can be dispersed highly uniformly in the stimulable phosphor layer in both the surface direction and the thickness direction of the phosphor layer. A phosphor sheet excellent in uniformity such as emission characteristics and sensitivity can be obtained.

  The crucibles 50 and 52 are made of a refractory metal such as tantalum (Ta), molybdenum (Mo), tungsten (W), and the like, and are energized from electrodes (not shown), like the crucible used for vacuum deposition by ordinary resistance heating. This is a crucible serving as a resistance heating source that generates heat by itself and heats / melts the filled film forming material to evaporate.

In the stimulable phosphor, the activator and the phosphor are, for example, about 0.0005 / 1 to 0.01 / 1 in molar concentration ratio, and most of the phosphor layer is the phosphor.
A crucible 52 for europium bromide (activator) with a small deposition amount is a lid having a slit-like steam outlet extending from the upper surface of a normal boat-type crucible in a direction coinciding with the arrangement direction of the crucible. It is obstructed by the body. In addition, a square cylindrical chimney (chimney) 52a having an upper and lower opening surface of the same shape is fixed to the vapor discharge port, and the vapor of the film forming material is discharged from the chimney 52a.

  As described above, although not shown, a resistance heating power source is connected to each crucible 52. Moreover, since an activator has little vapor deposition amount (evaporation amount), as an example, control of heating is performed by constant current control. Note that the heating control method of the crucible 52 is not limited to this, and various methods used in vacuum vapor deposition by resistance heating, such as a thyristor method, a DC method, and a thermocouple feedback method, can be used.

  On the other hand, the crucible 50 for cesium bromide (for phosphor) having a large deposition amount is a large drum-type (cylindrical) crucible. The crucible 50 has a slit-like steam outlet extending in the axial direction of the drum on the side surface of the drum. Further, a rectangular cylindrical chimney 50a having the same upper and lower opening surfaces is fixed to the vapor outlet, and similarly, the vapor of the film forming material is discharged from the chimney 50a. The crucible 50 is arranged so that the axis of the drum coincides with the arrangement direction of the crucible 50, that is, the slit-shaped chimney 50 a coincides with the arrangement direction of the crucible 50.

  By having such a chimney (chimney-like steam discharge part), when bumping occurs due to local heating or abnormal heating in the crucible, it is possible to prevent the film forming material from being unexpectedly ejected from the crucible. Contamination of the substrate S can be prevented. In particular, in the above-described medium vacuum deposition, it is necessary to bring the substrate S and the evaporation source close to each other as described above.

  Here, the crucible 50 for cesium bromide measures the temperature in the crucible, and controls the evaporation amount (that is, the deposition rate) of the film forming material from each crucible according to the result of the measurement. The vacuum vapor deposition method is performed.

  FIG. 3 shows a schematic view of the crucible 50. 3A is a top view, FIG. 3B is a partially cutaway front view (viewed from the same direction as FIG. 1B), and FIG. 3C is a side view (FIG. 1A). The figure seen from the same direction.

  As described above, the crucible 50 is a drum-type crucible, and a slit-like steam discharge port 50b that coincides in the axial direction is formed on the side surface of the drum, and the steam discharge port 50 has a rectangular tube whose upper and lower surfaces are open. A shaped chimney 50a is fixed. In the chimney 50a, a substantially Z-shaped rib 50c is disposed in order to support from the inside and improve the strength.

  Further, a shielding member 62 for preventing the bumped film forming material from being ejected is fixed in the crucible 50. The shielding member 62 is formed by folding a long rectangular plate material in the short direction to form a substantially T shape, and the attachment portion 62a is formed by vertically folding both longitudinal ends of the upper portion of the T shape upward. When viewed from above, the shielding member 62 is disposed in the crucible 50 (drum) so as to close the steam outlet 50 on the T-shaped upper surface, and the attachment portion 62a is fixed to the drum end surface from the inside.

Electrodes 60 are fixed to both end faces of the crucible 50 (drum).
The electrode 60 is connected to a resistance heating power source 20 (hereinafter simply referred to as a power source 20). The power source 20 is not particularly limited, and various types of power sources that are used for heat generation of a crucible serving as a resistance heating source in vacuum deposition by resistance heating can be used.

  In the illustrated example, a thermocouple 58 serving as temperature measuring means is inserted into the chimney 50a of the crucible 50 through the side surface (end surface in the slit extending direction). In order to prevent a temperature measurement error caused by a weak voltage from the power supply 20, the thermocouple 58 (its thermal contact) is preferably arranged so as not to contact the crucible 50. In the illustrated example, the thermocouple 58 is inserted from the end face of the chimney 50a in the slit extending direction, but the present invention is not limited to this, and the thermocouple 58 is inserted from the end face of the chimney 50a in the short slit direction. It is also preferable to insert a pair 58.

  In the crucible 50, the film forming material is filled so that the melted film forming material (melted evaporation source) does not come into contact with the shielding member 62 in a normal use state. Accordingly, the thermocouple 58 disposed in the chimney 50a does not contact the melt evaporation source. In the embodiment in which temperature measurement is performed without contact with the melt evaporation source, in order to perform highly accurate temperature measurement, the thermal contact of the thermocouple 58 is directly in contact with the film forming material vapor. Is preferred.

The heating control means 22 is connected to the thermocouple 58.
Here, the heating control means 22 is configured so that the temperature at the temperature measurement position becomes a predetermined temperature according to the temperature measurement result by the thermocouple 58 (that is, the evaporation amount of the film forming material becomes a predetermined rate). The power supplied from the power source 20 to the crucible 50 is controlled. Details of this control operation will be described below with reference to an operation flowchart shown in FIG.

When the vapor deposition operation is started, as shown in FIG. 4, first, the evaporation state is determined by measuring the temperature in the evaporation container (step A).
This is performed using, for example, a graph showing a relationship between the temperature in the evaporation container and the evaporation rate, or a comparison table created based on the graph, which is obtained in advance.

  The heating control means 22 according to the present embodiment initially has a crucible according to the temperature measurement result by the thermocouple 58 so that the temperature at the temperature measurement position becomes a predetermined temperature according to the temperature measurement result by the thermocouple 58. 50 heat generation (= heating of the film forming material) is controlled to control the evaporation amount of the film forming material, and feedback control is performed (step B).

  Then, the heating control means 22 continuously observes the progress of vapor deposition, and confirms that the evaporation amount (= deposition rate) of the film forming material is maintained within a predetermined range for a predetermined time (step) C: Y: That is, at the time of initial setting, the heating control method of the crucible 50 is switched from the feedback control method to heating under a constant condition (step D).

  That is, in this embodiment, in vacuum vapor deposition using resistance heating, the temperature is measured inside the crucible serving as a resistance heating source, and the crucible is heated according to the result, that is, the evaporation amount of the film forming material (= vapor deposition). The rate is initially stabilized by a method such as using a feedback control method, and after stabilization, switching to control that maintains the state realizes efficient control. Thereby, the evaporation amount of the film forming material, that is, the evaporation rate can be accurately controlled, and the phosphor layer having a predetermined film thickness can be stably formed.

  As described above, since the activator has a very small amount of vapor deposition (evaporation amount), in the above embodiment, the control of the heating and evaporation in the crucible 52 for the activator is constant current control. The invention is not limited to this, and also in the crucible 52 for the activator, the temperature of the crucible 52 is measured, and the vacuum is controlled according to the measurement result to control the deposition rate by controlling the heating. Needless to say, a vapor deposition method may be applied.

  Moreover, in the said embodiment, although temperature measurement is performed by all the crucibles 50 for fluorescent substances and feedback control of heating is carried out as a preferable aspect, this invention is not limited to this and is limited to this. You may make it control a crucible heating by measuring temperature for every predetermined number, such as 1 piece, 1 piece. In this case, the heating of the crucible may be individually controlled or the heating may be controlled for each of a plurality of crucibles corresponding to the temperature measurement. In addition, when a large number of crucibles are arranged as shown in the illustrated example when the temperature is measured for each predetermined number, it is a matter of course that the temperature measurement is preferably performed for each crucible at a predetermined interval.

  Hereinafter, the operation of forming the phosphor layer on the substrate S (manufacturing the phosphor sheet) by the manufacturing apparatus 10 will be described.

  First, the vacuum chamber 12 is opened, the substrate S is held on the substrate holding means 30 of the substrate holding and transport mechanism 14, cesium bromide is contained in all the crucibles 50, and europium bromide is contained in all the crucibles 52. Then, the shutter is closed and the vacuum chamber 12 is further closed.

Next, the vacuum evacuation means is driven to evacuate the vacuum chamber 12. When the inside of the vacuum chamber reaches 8 × 10 ⁻⁴ Pa, for example, the evacuation is continued and the gas introduction nozzle 18 enters the vacuum chamber 12. Argon gas is introduced, the pressure in the vacuum chamber 12 is adjusted to, for example, 1 Pa, and the resistance heating power source is driven to energize all the crucibles 50 and crucibles 52 to heat the film-forming material. After the elapse of time, the rotation drive source 44 is driven to start transporting the substrate S, the shutter is opened, and formation of the phosphor layer on the surface of the substrate S is started.

  During film formation, the temperature in the crucible 50 is measured by the thermocouple 58 in all the crucibles 50, and the heating control means 22 is shown in FIG. 4 so that the temperature becomes a predetermined temperature according to the result. Based on the operation flow chart, the power supplied from the power source 20 to the crucible 50 is controlled, the evaporation amount of the film forming material from each crucible 50 is controlled, and the deposition rate is controlled.

  When the reciprocation of the predetermined number of times of linear conveyance set according to the thickness of the phosphor layer to be formed is completed, the linear conveyance of the substrate S is stopped, the shutter is closed, the resistance heating power is turned off, and the gas The introduction of the argon gas by the introduction nozzle 18 is stopped, dry nitrogen gas or dry air is introduced, the inside of the vacuum chamber 12 is brought to atmospheric pressure, then the vacuum chamber is opened, and the substrate S on which the phosphor layer is formed, that is, The produced phosphor sheet is taken out.

  In addition, since this fluorescent substance sheet formed the fluorescent substance layer by controlling a vapor deposition rate according to the temperature measurement result in the inside of the crucible 50, it is a highly accurate film | membrane formed into a film with the appropriate vapor deposition rate It is a high quality one having a thick phosphor layer.

  The vacuum vapor deposition method and the vacuum vapor deposition apparatus according to one embodiment of the present invention have been described in detail above, but the present invention is not limited to the above embodiment, and various improvements and modifications can be made without departing from the spirit of the present invention. It goes without saying that changes may be made.

  For example, in the above embodiment, a two-layer vacuum deposition apparatus that heats two kinds of film forming materials with different crucibles, but the present invention is not limited to this, and all film forming materials are mixed and evaporated. It may be a unitary vacuum deposition apparatus housed in a source, or a three or more unit vacuum deposition apparatus. In the illustrated example, each film-forming material has a plurality of crucibles. However, the present invention is not limited to this, and the number of film-forming materials may be one or a certain crucible. The film forming material may be only one crucible, and the other film forming material may have a plurality of crucibles.

In addition, the above example is an example in which the present invention is used for film formation of a phosphor layer in the production of a phosphor sheet, but the present invention is not limited to this, and other than the phosphor layer, vacuum deposition is also performed. It can be used for various film formations.
Furthermore, although the apparatus of the illustrated example is an apparatus that performs film formation while linearly transporting the substrate, the present invention is not limited to this, and film formation is performed while the substrate is rotated (rotation, revolution, rotation). A so-called substrate rotation type vacuum deposition apparatus may be used.

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

〔Example〕
As a film forming material, a powder of cesium bromide (CsBr) having a purity of 4N or more was prepared.
As a result of analyzing trace elements in the material by ICP-MS (inductively coupled plasma spectroscopy-mass spectrometry), alkali metals (Li, Na, K, Rb) other than Cs in CsBr are each 10 ppm or less. Other elements such as alkaline earth metals (Mg, Ca, Sr, Ba) were 2 ppm or less. Since this material has high hygroscopicity, it was stored in a desiccator kept in a dry atmosphere with a dew point of −20 ° C. or less, and was taken out immediately before use.

As the substrate S, a 0.7 mm thick glass substrate was prepared.
This substrate S was mounted on the substrate holding means 30 of the manufacturing apparatus 10. The distance between the substrate S and the crucible 50 was 15 cm.
Further, the crucible 50 (made of Ta) was filled with the film forming material (CsBr). An R-type (platinum-rhodium) thermocouple 58 was brought into contact with and fixed to the bottom (outer surface) of the crucible 50 so that the temperature of the crucible 50 could be measured.

After completing the mounting of the substrate S and the loading of CsBr, the vacuum chamber 12 was closed, the main exhaust valve was opened, and the inside of the apparatus was evacuated to a vacuum degree of 2 × 10 ⁻³ Pa. Note that a combination of a rotary pump, a mechanical booster, and a diffusion pump was used as the vacuum exhaust device. Furthermore, a moisture exhaust cryopump was used to remove moisture.
Thereafter, the exhaust was switched from the main exhaust valve to the bypass, and Ar gas was introduced into the apparatus to obtain a vacuum degree of 1.0 Pa.

  Prior to the start of deposition, the substrate transport means 32 was driven to start transporting the substrate S (reciprocal transport), the power source 20 was driven to energize the crucible 50, and CsBr was heated and melted. And the temperature of the crucible 50 was measured with the thermocouple 58 fixed to the bottom (outer surface) of the crucible 50, and the temperature of the crucible 50 became a temperature commensurate with a predetermined evaporation rate based on measurement data prepared in advance. At that time, deposition began. Thereafter, this temperature was maintained by feedback control.

And here, after controlling to hold this temperature for 105 minutes from the start of deposition, the control was switched to the constant current value mode, and deposition was continued for another 11 minutes. At this time, the constant current value was the current value immediately before switching.
Here, the subsequent constant current value mode is not particularly limited, and other control methods such as a constant voltage mode and a constant power mode may be used.

After vapor deposition, nitrogen gas was introduced to return the inside of the vacuum chamber 12 to atmospheric pressure, and the substrate S was taken out from the manufacturing apparatus 10. On the coated substrate, a deposited layer (area 20 cm × 20 cm) having a structure in which columnar crystals were densely planted in a substantially vertical direction was formed.
Thereafter, the crucible 50 was replaced, and film formation similar to the above was performed four times, and a substrate S on which a total of five CsBr phosphor matrix layers were formed was produced.

[Comparative Example 1]
A substrate S on which a CsBr phosphor base material layer was formed was prepared using the same material and the same apparatus as in the example, but changing only the heating control method by the heating control means 22. The control method used here was a constant current control method from the beginning to the end of the deposition. The number of repetitions was set to 5 as in the example.

[Comparative Example 2]
Similarly to Comparative Example 1, the same material and the same apparatus as in Example were used, and only the heating control method by the heating control means 22 was changed, and the substrate S on which the CsBr phosphor base layer was formed was produced. The control method used here was a constant temperature control method from the beginning to the end (that is, a control method for keeping the temperature in the crucible 50 constant). The number of repetitions was set to 5 as in the example and comparative example 1.

  FIG. 5 shows the film thickness variation (ratio) and the average film thickness rate (average vapor deposition rate) for the substrate S on which the CsBr phosphor base material layer formed by the methods of Examples, Comparative Examples 1 and 2 is formed. The results of measurement (calculation) are summarized.

In addition, the film thickness fluctuation | variation in FIG. 5 (it respond | corresponds to the right scale shown by (circle) mark) is an average value of the ratio of the film thickness fluctuation | variation in the predetermined number of points on a board | substrate. The average film thickness rate (average vapor deposition rate: indicated by □, corresponding to the left scale) is a value obtained by dividing the average film thickness value by the vapor deposition time, and is a pseudo average vapor deposition rate. It is a value that can be said.
Moreover, 1-5 in each of an Example, the comparative example 1, and the comparative example 2 respond | corresponds to the frequency | count of repetition, and has shown reproducibility.

As shown in FIG. 5, in the case of the condition of Comparative Example 1, the film thickness distribution is not stable, it cannot be said that the control state is favorable, and the repeatability of the average film thickness rate is poor.
Also, in the case of the condition of Comparative Example 2, since feedback control is performed to the end, when the amount of material in the container is reduced, the correlation between the measured value and the evaporation rate becomes weak. Therefore, it cannot be said that the fluctuation of the film thickness and the repeatability of the average film thickness rate are satisfactory.

  On the other hand, in the case of the conditions of the example, the film thickness distribution and the repeatability of the average film thickness rate are clearly improved as compared with the conditions of the comparative example. When the film thickness distribution and the average film thickness rate are improved to this level, the practical reliability is greatly improved.

From the above results, the effects of the present invention are clear.
The above-described embodiments and examples are merely examples of the present invention, and the present invention is not limited thereto, and appropriate modifications and improvements can be made without departing from the scope of the present invention. Needless to say, it may be performed.

  For example, as described above, “for a while after the start of vapor deposition, the heating control of the evaporation container is continued for a predetermined time so that the value indicating the evaporation state of the film-forming material from the evaporation container becomes a predetermined value. The heating method used for the control in the first half and the latter half in the configuration of “the heating of the evaporation container is switched to a constant heating condition based on the preferred control condition found in the control process described above”, in addition to the exemplified method, Similar methods can be selected and used.

  In addition, the above-mentioned control for “a value indicating the evaporation state to be a predetermined value” is also measured by the temperature of the evaporation container, the temperature of the evaporation material, the temperature of the evaporation flow (vapor), and a sensor using a crystal resonator. It is possible to perform control based on various indexes such as the evaporation rate to be measured or the amount of time change in the thickness of the deposited film measured by a displacement measuring device using a laser.

(A) is a schematic front view of an example of the fluorescent substance sheet manufacturing apparatus using the vacuum evaporation method which concerns on one Embodiment of this invention, (B) is the schematic side view. It is a schematic plan view of the heating evaporation part of the fluorescent substance sheet manufacturing apparatus shown in FIG. (A) is a top view of the crucible of the phosphor sheet manufacturing apparatus shown in FIG. 1, (B) is the same schematic front view, and (C) is a schematic side view of the same. It is an operation | movement flowchart of the fluorescent substance sheet manufacturing apparatus which concerns on embodiment. It is a graph explaining the effect of an Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 (Phosphor sheet) Manufacturing apparatus 12 Vacuum chamber 14 Substrate holding conveyance means 16 Heating evaporation part 18 Gas introduction nozzle 20 (Resistance heating) Power supply 22 Heating control means 30 Substrate holding means 32 Substrate conveyance means 34 Guide rails 36, 48 Engagement Member 40 Screw shaft 42 Nut portion 44 Rotation drive source 50, 52 Crucible 58 Thermocouple 62 Shield member AD Operation steps

Claims (16)

When performing vacuum deposition to form a film on a substrate by depressurizing the inside of the vacuum chamber and energizing and heating an evaporation container for resistance heating containing a film forming material,
After controlling the heating conditions of the evaporation container for a predetermined time so that the value indicating the evaporation state of the film forming material from the evaporation container becomes a predetermined value, the evaporation container is heated under a constant heating condition. A vacuum evaporation method characterized by switching.   The vacuum deposition method according to claim 1, wherein after the deposition is started, the heating condition is controlled for a predetermined time, and then the evaporation container is switched to be heated while maintaining the heating condition when the predetermined time has elapsed.   2. The heating condition is controlled for a predetermined time before the start of vapor deposition, and then switched to heating the evaporation container while maintaining the heating condition when the predetermined time has elapsed, and then vapor deposition is started. The vacuum evaporation method as described in 2.   The vacuum deposition method according to claim 1, wherein the value indicating the evaporation state is a temperature of a film forming material in the evaporation container.   The vacuum deposition method according to claim 1, wherein the value indicating the evaporation state is a temperature of the evaporation container.   The vacuum deposition method according to claim 1, wherein the value indicating the evaporation state is a temperature of an evaporation flow above the evaporation container.   The vacuum deposition method according to claim 1, wherein the value indicating the evaporation state is an evaporation rate measured by a sensor using a crystal resonator.   The vacuum deposition method according to claim 1, wherein the value indicating the evaporation state is a time change amount of a film thickness of the deposited film measured by a displacement measuring device using a laser.   The vacuum deposition method according to claim 1, wherein the heating condition is based on an electric current.   The vacuum deposition method according to claim 1, wherein the heating condition is based on a voltage.   The vacuum deposition method according to claim 1, wherein the heating condition is based on electric power.   The vacuum evaporation method according to claim 1, wherein a plurality of the evaporation containers are provided, and the switching time is the same for all of these evaporation containers.   The vacuum evaporation method according to any one of claims 1 to 11, wherein a plurality of the evaporation containers are provided, and the switching time is individually determined in each of the evaporation containers. A vacuum chamber;
Exhaust means for exhausting the inside of the vacuum chamber;
A substrate holding means for holding a substrate to be deposited by the film forming material;
An evaporation vessel for resistance heating;
A resistance heating power source for supplying resistance heating power to the evaporation container;
A vacuum vapor deposition apparatus having a control means for controlling the heating of the evaporation container by driving the resistance heating power source,
After controlling the heating conditions of the evaporation container for a predetermined time so that the value indicating the evaporation state of the film forming material from the evaporation container becomes a predetermined value, the evaporation container is heated under a constant heating condition. A vacuum deposition apparatus having a control switching function for switching.   The vacuum deposition apparatus according to claim 14, wherein the control switching function gives priority to a switching instruction from an operator.   The vacuum deposition apparatus according to claim 14, wherein the substrate holding unit is linearly conveyed in a predetermined direction by a linear conveyance path.

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