JP2007270297A - Vacuum vapor deposition apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vacuum vapor deposition apparatus realizing a high use efficiency of a deposition material. <P>SOLUTION: The vacuum vapor deposition apparatus has a conveying means for linearly conveying a substrate back and forth and one or more rows of evaporation sources in which one or more evaporation sources are arranged in a direction perpendicular to the conveying direction. When the conveying means conveys the substrate back and forth, it turns back before the posterior end of the substrate in the traveling direction goes beyond an evaporation zone in which an evaporation stream from the rows of evaporation sources contacts the substrate to solve the problem. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention can produce a radiation image conversion panel that can greatly improve the utilization efficiency of a film forming material and can ensure the uniformity of the film thickness, in particular, a radiation image having a phosphor layer made of a stimulable phosphor. The present invention relates to a vacuum deposition apparatus suitable for manufacturing a conversion panel.

  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, Phosphors that exhibit stimulated emission according to the stored energy are known. This phosphor is called a stimulable phosphor (accumulating phosphor) and is used for various applications such as medical applications.

As an example, a radiation image conversion panel (hereinafter referred to as a conversion panel (stimulable phosphor panel (sheet)) having the photostimulable phosphor film (stimulable phosphor layer). Radiation image information recording / reproducing system using the above-mentioned)) is known, and is put into practical use as, for example, FCR (Fuji Computed Radiography) manufactured by Fuji Photo Film Co., Ltd.
In this system, radiation image information of a subject is recorded on a conversion panel (phosphor layer) by irradiating X-rays or the like through a subject such as a human body. After recording, the conversion panel is scanned two-dimensionally with excitation light to generate stimulated emission, and this stimulated emission light is photoelectrically read to obtain an image signal, and an image reproduced based on this image signal is A radiographic image of the subject is output to a display device such as a CRT or a recording material such as a photographic photosensitive material.

The conversion panel is usually prepared by dispersing a stimulable phosphor powder in a solvent containing a binder, and applying the paint to a glass or resin panel-like support (substrate). Created by drying.
On the other hand, as shown in Patent Document 1 and Patent Document 2, a conversion panel in which a phosphor layer is formed on a substrate by a vapor deposition method (vacuum film forming method) such as vacuum evaporation or sputtering is also known. ing. Phosphor layers by vapor deposition are formed in a vacuum, so there are few impurities, and since there are almost no components such as binders other than stimulable phosphors, there is little variation in performance and luminous efficiency. Has excellent properties of being very good.

By the way, as a method for reading a phosphor sheet from which a radiographic image has been taken, a linear light source is moved in a direction orthogonal to the extending direction, and the phosphor sheet is irradiated with excitation light, while extending in the same direction as the light source. There is a method of reading the photostimulated luminescence with a line sensor that exists and moves synchronously.
In reading a phosphor sheet using such a line sensor, in order to read a suitable image, the gap between the surface of the phosphor layer of the phosphor sheet and the line sensor (light receiving surface) is properly set. For this purpose, it is important that the thickness of the phosphor layer is uniform.

That is, inconveniences such as blurring of the read image occur if the stimulated emission light is not focused on the line sensor. In particular, in medical applications such as the FCR, such deterioration in image quality becomes a serious problem that leads to differences in diagnosis results and misdiagnosis. For this reason, in order to properly read the radiation image photographed on the phosphor sheet, it is necessary to properly focus the stimulated emission light generated from the phosphor sheet on the line sensor (its light receiving surface).
As a matter of course, in order to properly focus the stimulated emission light on the line sensor, it is necessary to keep the gap between the phosphor sheet and the line sensor properly. The gap between the line sensor and the phosphor sheet is usually about 100 μm. On the other hand, in a phosphor sheet having a phosphor layer formed by vapor deposition, the thickness of the phosphor layer is usually about 500 μm, and when it is thick, it may exceed 1000 μm. Therefore, when considering the size of the gap between the two, the film thickness distribution of the phosphor sheet becomes a large error factor of the gap between the line sensor and the phosphor sheet.

Usually, in vacuum deposition, a deposition film with a good film thickness distribution is formed by performing deposition while rotating (rotating, revolving, or revolving) the substrate in the information of the evaporation source (for example, a crucible for resistance heating). is doing. However, in the formation of the phosphor layer by rotating the substrate, it is difficult to stably satisfy the film thickness uniformity required for the conversion panel.
In order to solve such a problem, the present applicant arranges a manufacturing apparatus for forming a phosphor layer while arranging a vapor deposition source in one direction and reciprocating the substrate in a direction orthogonal to the arrangement direction. It has been proposed (see Patent Document 3).

Japanese Patent Publication No. 7-18958 JP 2002-181997 A JP 2005-351762 A

  According to this apparatus, by arranging a plurality of evaporation sources in a row, the amount of evaporation of the film forming material in this arrangement direction is made uniform, and the substrate is reciprocated in a direction perpendicular to this arrangement direction, The exposure amount of the deposition vapor can be made uniform over the entire surface of the substrate. Therefore, it is possible to form a phosphor layer with excellent film thickness uniformity.

However, in such vacuum deposition in which the substrate is reciprocated in a straight line, in order to ensure film thickness uniformity, the region where the evaporation flow from the evaporation source such as a crucible reaches the substrate (deposition is performed). It is preferable that the substrate is transported at a constant speed over the entire region). For this purpose, it is necessary to fold the transport after the entire surface of the substrate exceeds the vapor deposition region and transport the substrate back and forth.
When such a transfer route is set, the area where the substrate is subjected to vapor deposition is narrower than the transfer area of the substrate, and as a result, the utilization efficiency of the film forming material is deteriorated.

  An object of the present invention is to solve the above-described problems of the prior art, in which the evaporation sources are arranged in one direction and the substrate is reciprocated linearly in a direction perpendicular to the evaporation source arrangement direction, A vacuum vapor deposition apparatus for forming a photostimulable phosphor layer or the like by vapor deposition, which can improve the utilization efficiency of the film forming material, and preferably can ensure good film thickness uniformity. To provide an apparatus.

  In order to achieve the above object, a vacuum deposition apparatus according to the present invention includes a vacuum chamber, a transport unit that linearly transports a substrate back and forth, and a reciprocal transport direction that is disposed below a substrate transport position by the transport unit. And a heating evaporation section having one or more evaporation source arrays arranged in the reciprocating conveyance direction, each of the evaporation source arrays. When the maximum point of the film thickness distribution in the reciprocating conveyance direction obtained by performing deposition while fixing the substrate to the upper part every time is Tmax, and the point where the film thickness is substantially 0 is Tmin, The conveying means provides a vacuum deposition apparatus characterized in that the substrate is reciprocated before the rear end of the substrate in the conveyance direction reaches the Tmin, which is the most downstream in the conveyance direction, and the substrate is reciprocated.

In such a vacuum vapor deposition apparatus of the present invention, it is preferable that the transport means changes the transport speed of the substrate during linear transport except when the substrate is folded back. With the center position in the reciprocating transport direction as a reference position, the transporting means is configured such that the transport speed of the substrate when the reference position of the substrate passes through the intermediate portion of the reciprocating transport is lower than a predetermined transport speed before and after returning the transport. It is preferable to change the conveyance speed of the substrate so that
Further, the vapor deposition source row is arranged in the reciprocating transport direction and has two or more, and the transport means has a rear end in the transport direction of the substrate between the Tmax at the most downstream in the transport direction and the Tmax immediately upstream thereof. It is preferable that the substrate is reciprocated by folding the substrate when it is positioned at the position, and further, a phosphor layer made of a stimulable phosphor is preferably formed on the surface of the substrate.

According to the present invention having the above configuration, the substrate can be exposed to the evaporation flow (evaporation vapor of the film forming material) from the evaporation source over the entire area of the reciprocating conveyance area of the substrate. Vapor deposition can be performed with a high efficiency of using a film forming material. In addition, there is no waste of film forming material, which is advantageous in terms of environmental measures. Therefore, the present invention is suitable for manufacturing a radiation image conversion panel that requires the use of an expensive film forming material, particularly a radiation image conversion panel that uses a stimulable phosphor.
Further, by arranging the evaporation sources in one direction and reciprocating the substrate in the direction orthogonal to the evaporation source arrangement direction, it is possible to ensure a certain degree of film thickness uniformity, but preferably by changing the conveyance speed, Preferably, film thickness uniformity is further improved by changing the transport speed so that the transport speed when the center of the substrate passes through the center position of the reciprocating transport is lower than the transport speed before and after the return of the transport. A deposited film can be formed.

  Hereinafter, the vacuum vapor deposition apparatus of the present invention will be described in detail based on the preferred embodiments shown in the accompanying drawings.

In FIG. 1, the conceptual diagram of an example which utilized the vacuum evaporation system of this invention for the manufacturing apparatus of a radiation image conversion panel (stimulable phosphor panel) is shown. 1A is a front view, and FIG. 1B is a side view.
A manufacturing apparatus 10 shown in FIG. 1 manufactures a radiation image conversion panel (hereinafter referred to as a conversion panel) by forming a phosphor layer made of a stimulable phosphor by vacuum deposition on the surface of a substrate S. Basically, the vacuum chamber 12, the substrate transport mechanism 14, the heating evaporation unit 16, and the gas introduction unit 18 are configured.

  Such a manufacturing apparatus 10 reciprocates the substrate S linearly, and separately evaporates the phosphor film-forming material and the activator film-forming material, and the surface of the substrate S by binary vacuum deposition. Then, a phosphor layer is formed to produce a radiation image conversion panel.

In the conversion panel manufactured by the manufacturing apparatus 10, the substrate S is not particularly limited, and various types used in known radiation image conversion panels can be used.
Examples include plastic plates and plastic sheets (films) formed from cellulose acetate, polyester, polyethylene terephthalate, polyamide, polyimide, triacetate, polycarbonate, etc .; quartz glass, alkali-free glass, soda glass, heat-resistant glass (Pyrex ^™, etc.), etc. Glass plates and glass sheets formed from: metal plates and metal sheets formed from metals such as aluminum, iron, copper, and chromium; a coating layer such as a metal oxide layer is formed on the surface of such metal plates Examples of such a plate or sheet are as follows.
Further, the substrate S has a protective layer for protecting the base material of the substrate S such as an aluminum plate on the surface (phosphor layer forming surface), a reflective layer for stimulated emission light, and this reflective layer, as necessary. The protective layer may be provided. In this case, the phosphor layer is formed on these layers.

Moreover, in the conversion panel manufactured by the manufacturing apparatus 10, there is no particular limitation on the stimulable phosphor (accumulative phosphor) forming the phosphor layer, and various known stimulable phosphors can be used. is there.
As an example, an alkali halide photostimulable phosphor represented by a general formula “M ^I X · aM ^II X ′ ₂ · bM ^III X ″ ₃ : cA” disclosed in JP-A-61-72087 is disclosed. It is preferably used.
(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 at least one trivalent metal selected from the group consisting of Ni, M ^III is, Sc, Y, La, Ce , Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, At least one trivalent metal selected from the group consisting of Tm, Yb, Lu, Al, Ga and In, and X, X ′ and X ″ are selected from the group consisting of F, Cl, Br and I A is from Eu, Tb, Ce, Tm, Dy, Pr, Ho, Nd, Yb, Er, Gd, Lu, Sm, Y, Tl, Na, Ag, Cu, Bi, and Mg. At least one selected from the group consisting of . Also, a 0 ≦ a <0.5, a 0 ≦ b <0.5, it is 0 <c ≦ 0.2.)
Among them, an alkali halide photostimulable phosphor in which M ^I contains at least Cs, X contains at least Br, and A is Eu or Bi in that it has excellent photostimulated emission characteristics. Among them, a photostimulable phosphor represented by the general formula “CsBr: Eu” is particularly preferable.

  In addition, U.S. Pat. No. 3,859,527, JP-A-55-12142, 55-12144, 55-12145, 56-116777, 58-69281. 58-206678, 59-38278, 59-75200, and the like, various photostimulable phosphors disclosed in each publication can be suitably used.

In the manufacturing apparatus 10, 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 means 18 also has a connection means with a cylinder or the like, a gas flow rate adjustment means, or the like (or is connected thereto), and the inside of a known vacuum chamber 12 used in a vacuum deposition apparatus or a sputtering apparatus ( It is a means for introducing gas into the film forming system. In the illustrated example, an inert gas such as argon gas or nitrogen gas is introduced into the vacuum chamber 12 by using the gas introduction means 18 in order to form a phosphor layer by vacuum deposition under medium vacuum, which will be described later. To do.

A vacuum pump (not shown) is connected to the vacuum chamber 12.
The vacuum pump is a known one such as an oil diffusion pump, a cryopump, a turbo molecular pump, or the like. Further, as an auxiliary, a cryocoil or the like may be used in combination. In addition, in the manufacturing apparatus 10 for forming the phosphor layer made of the photostimulable phosphor described above, the ultimate vacuum in the vacuum chamber 12 is preferably 8.0 × 10 ⁻⁴ Pa or less.

  The substrate transport mechanism 14 holds the substrate 12 and reciprocates along a linear transport path, and includes a substrate holding unit 24 and a transport unit 26.

The conveying means 26 is a linear motor guide having a guide rail 30 and an engagement member 32 engaged with the guide rail 30 to be guided (guided), a ball screw including a screw shaft 34 and a nut 36, and a rotational drive of the screw shaft 34. This is a known linear moving mechanism using a screw transmission having a source 38 and the like.
The rotational drive source 38 is capable of forward and reverse rotation. In addition, the rotation drive source 38 is connected to a conveyance control means 40 that controls the reciprocal conveyance of the substrate S.

On the other hand, the substrate holding means 24 includes a base 42 and a holding member 44.
The base 42 is a rectangular plate-like member that fixes the nut 36 and the engaging member 32 of the conveying means 26 to the upper surface. The holding member 44 is fixed to the base 42 so as to hang from the four corners, and holds the substrate S at the lower end. The method for holding the substrate S by the holding member 44 is not particularly limited, and a holding member such as a method using suction / adsorption, a frame body for holding the periphery of the substrate S from below (that is, placing the four sides of the substrate S). Any known method for holding a plate-like member, such as a method using a screw, a method using a screw screwed to the substrate S from the back side, or the like can be used.
The substrate holding means 24 is linearly moved by the conveying means 26 in a predetermined direction (the arrow x direction in FIG. 1A and the direction perpendicular to the paper surface in FIG. 1B).

In the manufacturing apparatus 10 of the illustrated example, the substrate holding means 24 is transferred by the transfer means 26 by driving the rotation drive source 38 and rotating the screw shaft 34 while holding the substrate S by the substrate holding means 24. 26, the substrate S is reciprocated linearly.
As will be described later, in the illustrated example, the transport of the substrate S is made linear, and a plurality of evaporation sources are arranged in a direction orthogonal to the transport direction, whereby a phosphor layer with high uniformity of film thickness distribution is obtained. The formation of is realized.

The reciprocal conveyance of the substrate S (drive of the rotational drive source 38) is controlled by the conveyance control means 40.
Note that the number of reciprocating conveyances may be appropriately determined according to the target film thickness of the phosphor layer, the target film thickness distribution uniformity, and the like.
Also, the transport speed of the substrate S is not particularly limited, and may be determined as appropriate according to the transport speed limit of the apparatus, the number of reciprocal transports, the film thickness of the target phosphor layer, and the like.
In the present invention, the substrate holding means 24 is not limited to the above-described configuration, and all known plate-like linear reciprocating means can be used.

A heating evaporation unit 16 is disposed below the vacuum chamber 12.
For example, the heating evaporation unit 16 uses a resistance heating crucible 50 as an evaporation source (evaporation source), and heats and evaporates the film forming material by resistance heating.
Although not shown, a shutter that shields the vapor of the film forming material from the heating evaporation unit 16 (the crucible 50) is disposed on the heating evaporation unit 16. Note that the present invention is not limited to heating the film forming material by resistance heating, and any of various heating methods used in vacuum vapor deposition such as induction heating and electron beam heating can be used.

As described above, the manufacturing apparatus 10 of the illustrated example, as a preferred embodiment, heats / fires the phosphor film-forming material of the stimulable phosphor and the film-forming material of the activator independently. The phosphor layer is formed by evaporating binary (multi-element) vacuum deposition. For example, in the case of CsBr: Eu exemplified as the preferable stimulable phosphor, cesium bromide (CsBr) which is a film forming material of the phosphor and europium bromide (EuBr) which is a film forming material of the activator component. _x (x is usually 2 to 3, but 2 is preferred)) is evaporated by heating independently.
The crucible 50 is formed by combining a phosphor crucible 50a for heating and evaporating a phosphor film forming material and an activator film forming crucible 50b for heating and evaporating an activator film forming material.

  The vacuum vapor deposition apparatus of the present invention is not limited to the one that performs binary (multi-element) vacuum deposition, and of course, the vacuum vapor deposition apparatus may perform unitary vacuum deposition.

In the manufacturing apparatus 10 of the illustrated example, the phosphor crucible 50a and the activator film-forming crucible 50b are arranged in the reciprocating conveyance direction of the substrate S as a preferred embodiment in which a phosphor layer having a more uniform composition is obtained. .
Further, the phosphor crucible 50a and the activator film forming crucible 50b are electrically insulated (or further thermally insulated), and heating can be controlled independently of each other.

As shown in FIGS. 1B and 2 (schematic top view), in the manufacturing apparatus 10, six crucibles 50 are arranged in a direction orthogonal to the reciprocating conveyance direction (arrow x direction) of the substrate S. The Further, the manufacturing apparatus 10 has two rows of the six crucibles 50 arranged in the reciprocating conveyance direction. Hereinafter, for convenience, one of the six crucibles 50 will be referred to as a first evaporation source row 54 and the other as a second evaporation source row 56.
The number of crucibles 50 in the evaporation source row is not limited to six, but may be one, may be 2 to 5, or may be 7 or more. In consideration of the film thickness uniformity in the direction orthogonal to the reciprocating conveyance direction of the substrate S, it is preferable to arrange a plurality of crucibles in this direction.

  In the present invention, the number of crucible 50 rows (evaporation source rows) is not limited to two, and may include only one evaporation source row, as will be described later, or 3 It may have one or more evaporation source rows.

  In the manufacturing apparatus 10 which is a vacuum deposition apparatus of the present invention, as described above, the substrate 12 is linearly reciprocated and the crucible 50 serving as a resistance heating evaporation source is perpendicular to the reciprocating direction of the substrate S. Further, by arranging a plurality of layers, the entire surface of the substrate 12 is uniformly exposed with the vapor of the film forming material, thereby enabling formation of a phosphor layer with extremely high film thickness distribution uniformity.

That is, the substrate 12 is linearly reciprocated and a plurality of crucibles (resistance heating evaporation sources) are linearly arranged in a direction perpendicular to the conveyance direction, thereby evaporating the substrate 12 in a direction perpendicular to the conveyance direction. Since the exposure amount of the flow (evaporation vapor of the film forming material) can be made uniform, the vapor of the film forming material can be uniformly exposed on the entire surface of the substrate 12 with a very simple configuration, and the film thickness distribution can be uniform. A high phosphor layer can be formed. In particular, in vacuum evaporation at medium vacuum, which will be described later, there is a collision between gas particles such as argon and evaporated film forming material, so that the distance between the substrate and the evaporation source is larger than that in normal high vacuum evaporation. Since it is necessary to make it narrower, the film forming material reaches the substrate 12 before diffusing into the system, so that 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 crucible 50 (phosphor crucible 50a and activator film forming crucible 50b) is made of tantalum (Ta), molybdenum (Mo), tungsten (W), etc., as in the case of the crucible used for vacuum evaporation by normal resistance heating. This is a crucible serving as a resistance heating evaporation source which is made of a high melting point metal and generates heat when energized from an electrode (not shown) 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. Therefore, the heating amount (energization amount) of the phosphor crucible 50a and the activator film forming crucible 50b is set so that the amount of the phosphor and the activator in the phosphor layer 14 is the target concentration ratio. Be controlled. Further, the film forming crucible 50b for the activator may be smaller than the phosphor crucible 50a.
The heating control of the crucible 50 may be performed by a known method used in vacuum deposition by resistance heating, such as a thyristor method, a DC method, or a feedback method. Further, these controls may be performed according to the temperature measurement result of the crucible, the evaporation amount measurement using a crystal resonator, and the like, similarly to the vacuum vapor deposition by normal resistance heating. Further, the activator film-forming material having a small evaporation amount may be controlled with constant current.

  Here, in the manufacturing apparatus 10 which is a vacuum deposition apparatus of the present invention, the substrate transport means 14 of the substrate S performs deposition by fixing the substrate S to the upper portion for each row of crucibles 50 (evaporation source row). In the film thickness distribution (film thickness distribution in the reciprocating conveyance direction) obtained at this time, the maximum point is Tmax, and the point where the film thickness is substantially zero is Tmin. Before the end reaches Tmin, which is the most downstream (the most downstream in the transport direction), the transport is folded back and the substrate S is transported back and forth.

In the present invention, the point where the film thickness is substantially 0 is the point where the film thickness is 1/10000 with respect to Tmax. For example, if Tmax is 700 μm, the position where the film thickness is 0.07 μm is defined as Tmin, where the film thickness is substantially zero.
When performing binary (multi-element) vacuum deposition as shown in the figure, the return of the conveyance is usually in accordance with the film thickness distribution of the film formed by the evaporation sources of both (all) film forming materials. To do. However, as shown in the illustrated example, when the deposition amount of one film forming material (that is, the film forming material for the activator) is extremely small, the film forming material that is deposited in a large amount (that is, the film forming material for the phosphor). The return position of the reciprocating conveyance may be set only in accordance with the film thickness distribution.

For example, when the evaporation source row is one row and the substrate S is fixed above the evaporation source row and vacuum deposition is performed, the film thickness distribution schematically shown in FIG. When the phosphor layer is formed on the horizontal axis (the position in the reciprocating conveyance direction of the substrate S), the substrate conveyance means 14 (conveyance control means 40) determines that the rear end of the substrate S reaches Tmin on the downstream side. Then, the conveyance is folded back and the substrate S is reciprocated.
In other words, at the position where the rear end of the substrate S is on the Tmax side with respect to Tmin, the conveyance is turned back and the substrate S is reciprocated.

In addition, as shown in the example, there are two evaporation source rows of the first evaporation source row 54 and the second evaporation source row 56, and when the vacuum evaporation is performed in the same manner, each of the evaporation source rows has a structure shown in FIG. In the case where the phosphor layer having the film thickness distribution schematically shown in B) is formed, the substrate transfer means 14 is arranged so that the rear end of the substrate S reaches the most downstream Tmin1 and before reaching the same Tmin2. Then, the conveyance is folded back and the substrate S is reciprocated.
In other words, the substrate S is reciprocated by returning the conveyance at the position where the rear end of the substrate S is on the Tmax1 side from Tmin1 and the position where the rear end of the substrate S is on the Tmax2 side from Tmin2.

Further, when there are three evaporation source rows and the same vacuum deposition is performed, a phosphor layer having a film thickness distribution schematically shown in FIG. 3C is formed by each evaporation source row. First, before the rear end of the substrate S reaches the most downstream Tmin1 and before reaching the same Tmin3, the substrate S is returned and the substrate S is reciprocated.
In other words, the substrate S is reciprocated by returning the conveyance at a position where the rear end of the substrate S is on the Tmax1 side from Tmin1 and a position where the rear end of the substrate S is on the Tmax3 side from Tmin3.

In addition, as shown in FIGS. 3B and 3C, when a plurality of evaporation source arrays are provided, the substrate is folded so that the rear end of the substrate S reaches the most downstream Tmax. It is preferable to perform S reciprocating conveyance.
That is, in the case of FIG. 3B having two rows of evaporation source rows, the substrate S is reciprocated by returning the conveyance before the rear end of the substrate S reaches the downstream Tmax1 and before reaching the same Tmax2. It is preferable to carry.
Further, in the case of FIG. 3C having three evaporation source rows, the conveyance of the substrate S is folded before the rear end of the substrate S reaches the most downstream Tmax1 and before reaching the same Tmax3. It is preferable to perform reciprocal conveyance. In other words, the substrate S is reciprocated by returning the conveyance at a position where the rear end of the substrate S is on the Tmax2 side from Tmax1 and a position where the rear end of the substrate S is on the Tmax2 side from Tmax3. In particular, it is preferable to reciprocate the substrate S so that a part of the substrate S is always above Tmax2.

As in the present invention, in vacuum deposition in which evaporation sources are arranged in one direction and the substrate S is reciprocally conveyed in a direction orthogonal to the evaporation source row, the region where the deposition is performed in terms of uniformity of layer thickness ( In the region where the substrate S is in contact with the evaporation flow), that is, in FIG. 3, the region above Tmin at both ends in the reciprocating conveyance direction is preferably reciprocated so that the entire surface of the substrate S passes at a constant speed.
Here, when the substrate S is transported back and forth, it is necessary to decelerate and accelerate to return the transport. Accordingly, in order to transport the entire surface of the substrate S at a constant speed in the entire region where the vapor deposition is performed (vapor deposition region), the rear end of the substrate S is to a position exceeding the vapor deposition region, that is, to a position exceeding the most downstream Tmin. It is necessary to transport the substrate S.
Therefore, when such a reciprocating transfer is performed, the region where the substrate S is subjected to vapor deposition is narrower than the transfer region of the substrate S, and as a result, the utilization efficiency of the film forming material is deteriorated. As described above.

On the other hand, in the present invention, as described above, before the rear end of the substrate S reaches the most downstream Tmin, the conveyance is folded back and the substrate S is reciprocated. In the case of the vapor deposition region, that is, FIG.
Therefore, according to the present invention, it is possible to improve the utilization efficiency of the film forming material, and it is possible to perform vacuum deposition that is very advantageous in terms of production cost, environmental pollution, and the like. In particular, phosphors, particularly photostimulable phosphors (especially CsBr: Eu in particular) are expensive in terms of raw materials, and thus have a great effect of reducing production costs. Further, since the reciprocating conveyance distance is shortened and the use efficiency of the film forming material is high, the vapor deposition time can be shortened and the productivity can be improved.

Here, according to the present invention, the evaporation source array is an evaporation source array, and the substrate S is linearly reciprocated in a direction orthogonal to the extending direction of the evaporation source array, thereby providing a certain degree of film thickness uniformity. It can be secured.
However, since the back-and-forth transfer is folded in a state where the rear end of the substrate S exists in the vapor deposition region, the vicinity of the end of the substrate S is vapor-deposited as compared with other regions by the deceleration and acceleration of the conveyance for the folding. Increases time spent in the area. As a result, the exposure amount of the evaporative flow fluctuates in the reciprocating conveyance direction of the substrate S, and the film thickness distribution is generated in a state where the layer thickness of the central portion of the substrate S becomes thin.

  In order to eliminate such inconveniences, in the present invention, as a preferred mode, the substrate transport unit 14 (transport control unit 40) is configured to perform linear transport other than folding (that is, during acceleration for transport folding and The substrate S transport speed is changed during linear transport except during deceleration.

The speed pattern for transporting the substrate S is not particularly limited, and a speed pattern that makes the time for the central portion of the substrate S to stay on Tmax may be set as appropriate.
That is, in the present invention, the film thickness distribution resulting from the above factors is the size of the substrate S, the transport speed of the substrate S, the flow of the evaporation flow from the evaporation source row (that is, the substrate is fixed on each of the above-described vapor deposition rows). It varies depending on various factors, such as the distribution of film thickness at the time of vapor deposition) and the interval between evaporation source rows when there are a plurality of evaporation source rows. Therefore, in accordance with these, a speed pattern may be appropriately determined so that the portion where the layer pressure becomes thin increases the time spent on Tmax.

As a preferred example, with the center of the substrate (the center in the reciprocating transport direction) as the reference position, the transport speed when this reference position passes through the intermediate part of the reciprocating transport (the intermediate position of the reciprocating transport) A speed pattern is exemplified that is lower than a predetermined speed (speed before deceleration and speed after acceleration) before and after folding the substrate. That is, in this speed pattern, after the conveyance is turned back to a predetermined speed, the conveyance speed is decelerated before the reference position reaches the intermediate portion, and the conveyance speed is increased after the reference position passes the intermediate portion.
In general, when the evaporation source row is an odd number row, the upper portion of the evaporation source row located at the center in the reciprocating conveyance direction of the substrate S (usually, the position of Tmax of this evaporation source row) is When the evaporation source row is an even row, the middle of the two evaporation source rows located at the center in the reciprocating conveyance direction of the substrate S (normally, the middle position of Tmax of the two evaporation source rows) Usually, the intermediate part of the reciprocating conveyance is used.

  FIG. 4 shows an example of a speed pattern that lowers the transport speed (lower the central speed) at the intermediate position. FIG. 5 shows the CsBr layer using the manufacturing apparatus 10 shown in FIG. 1 and the fluctuation pattern of the transport speed shown in FIG. The film thickness distribution at the time of forming is shown. FIG. 5 also shows the film thickness distribution when the phosphor layer is formed on the substrate S in exactly the same manner except that reciprocal conveyance is performed at a constant speed (constant speed) of 200 mm / sec shown in FIG. To do.

In FIG. 4, the position of the conveyance distance 0 on the horizontal axis is the intermediate part of the reciprocating conveyance, that is, the middle position between the first evaporation source row 54 and the second evaporation source row 56.
In this reciprocating conveyance, the substrate S is folded back at a position where the reference position of the substrate S is 250 mm from the intermediate portion, and is set to 200 mm / sec at the position of 210 mm. Is set to 100 mm / sec. When the position is -130 mm, the speed is increased and the transfer speed is set to 200 mm / sec at the position of -150 mm. When the position is -210 mm, the speed is decreased and the transfer is performed at the position of -250 mm. Wrap.
On the other hand, in the reciprocal conveyance at a constant speed, the conveyance is turned back at a position where the reference position of the substrate S is 250 mm from the intermediate position, the conveyance speed is 200 mm / sec at the position of 200 mm, and the substrate S is conveyed at a constant speed of 200 mm / sec. When the position becomes −200 mm, the speed is reduced and the conveyance is turned back at the position −250 mm.
That is, both are symmetrical transport patterns centered on the intermediate position.

As the substrate S, an aluminum plate having a thickness of 10 mm and 430 × 430 mm was used. The distance between the crucible 50 (evaporation source) and the substrate S was 10 cm, and the distance 56 between the first vapor deposition source row 54 and the second vapor deposition source row (the distance between the center positions in the reciprocating conveyance direction of the crucible 50a) was 210 mm. .
Furthermore, vapor deposition, after reducing the pressure of the vacuum chamber 12 to 2 × 10 ^-3 Pa, and 1Pa argon gas was introduced performs control to the heating temperature of the cesium bromide as a constant 670 ° C., When the film thickness of the CsBr layer phosphor layer reached about 700 μm, the film formation was completed. The heating temperature was controlled by feedback control using a temperature measurement result by an R-type (platinum-rhodium) thermocouple inserted in the crucible 50c.
The film thickness distribution was obtained by measuring the surface shape of the formed CsBr layer with a laser displacement meter. The film thickness distribution of the phosphor layer shown in FIG. 5 is a film thickness distribution normalized by setting the position of the maximum thickness to 1, and the position of 0 is the reference position of the substrate S.

  As shown in FIG. 5, by performing reciprocal conveyance with a speed pattern that lowers the conveyance speed at the intermediate portion, the film thickness distribution is smaller than the reciprocal conveyance with a constant conveyance speed, that is, the film thickness is uniform. A phosphor layer (vacuum deposited film) having excellent properties can be formed.

In the present invention, as the speed pattern for changing the conveyance speed, a speed pattern corresponding to the film thickness distribution obtained when the film is formed with the substrate stopped as shown in FIG. 3 is also suitable. Is available.
Specifically, in a state where the substrate S is fixed, a film thickness distribution is obtained when film formation is performed by all the evaporation source arrays instead of individual evaporation source arrays as shown in FIG. A method of reciprocating the substrate with a speed pattern in which the profile is turned upside down is exemplified.

As described above, the present invention is not limited to the binary vacuum deposition as in the illustrated example. However, when forming the phosphor layer made of the stimulable phosphor as in the illustrated example, The phosphor layer is preferably formed by binary (multi-component) vacuum deposition in which a body film-forming material and an activator film-forming material are heated / evaporated independently.
In this case, it is natural that the evaporation amount of the activator is controlled so that the concentration of the activator in the phosphor layer becomes a target value.

There are no particular limitations on the conditions for vacuum deposition, and the conditions may be appropriately determined according to the film forming material used.
Here, in the production apparatus 10 of the present invention, the above-mentioned various photostimulable phosphors, particularly alkali halide photostimulable phosphors, and in particular, photostimulable phosphors represented by the general formula “CsX: Eu”. In particular, when a phosphor layer made of CsBr: Eu is formed by vacuum deposition, the system is once evacuated to a high degree of vacuum, and then argon gas, nitrogen gas, or the like is introduced into the system. It is preferable that the degree of vacuum is about 0.01 to 3 Pa (hereinafter referred to as medium vacuum for convenience), and vacuum deposition is performed by heating the film forming material by resistance heating or the like under vacuum.
A phosphor layer made of a photostimulable phosphor formed by vacuum deposition has a columnar crystal structure in many cases. The phosphor layer obtained by forming under such a medium vacuum, particularly the CsBr: Eu The alkali halide phosphor layer such as has a particularly good columnar crystal structure, and is preferable in terms of photostimulable light emission characteristics and image sharpness.

  Hereinafter, an 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 12 is held by the substrate holding means 24 of the substrate transport mechanism 14, and the phosphor film forming material is used for all the phosphor crucibles 50a for all activators. The crucible 50b is filled with a predetermined amount of the film forming material of the activator. Thereafter, the upper shutter of the crucible 50 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 gas introduction means 18 keeps the evacuation inside the vacuum chamber 12. Argon gas is introduced to adjust the pressure in the vacuum chamber 12 to, for example, 1 Pa, and further, the resistance heating power source is driven to energize all the crucibles 50 to heat / melt the film forming material for a predetermined time. After the elapse of time, the rotary drive source 38 is driven to start reciprocating conveyance of the substrate 12, the shutter is opened, and formation of the phosphor layer on the surface of the substrate 12 is started.
Here, the reciprocal conveyance is performed by folding the conveyance before the rear end of the substrate S reaches Tmin1 and before the rear end of the substrate S reaches Tmin2, and the conveyance control means 40 is configured as described above. The drive of the rotational drive source 38 is controlled so as to perform the reciprocal conveyance. Preferably, during film formation, the transport speed of the substrate S at the time of linear transport during reciprocal transport is changed according to a preset speed pattern.

  When a predetermined number of linear reciprocating conveyances set according to the film thickness of the phosphor layer to be formed, etc., the conveyance of the substrate S is stopped, the shutter is closed, the resistance heating power is turned off, and the gas is introduced. The introduction of argon gas by the means 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 12 is opened, and the substrate S on which the phosphor layer is formed, that is, The produced phosphor sheet is taken out.

  The vacuum deposition apparatus of the present invention has been described in detail above, but the present invention is not limited to the above examples, and various improvements and modifications may be made without departing from the scope of the present invention. Of course.

For example, the above-described example is an example in which the present invention is used for manufacturing a radiation image conversion panel having a phosphor layer made of a stimulable phosphor. However, the present invention is not limited to this. The present invention can also be suitably used for a radiation image conversion panel having a phosphor layer composed of a columnar crystal of phosphor, such as a radiation scintillator panel having a phosphor layer composed of a columnar crystal of phosphor such as cesium fluoride. Moreover, the vacuum evaporation apparatus of this invention can be utilized for various vacuum evaporation besides manufacture of a radiation image conversion panel.
In particular, as described above, a phosphor made of a photostimulable phosphor as shown in the example in that high-precision film thickness uniformity is required and the film forming material is often expensive. It is suitable for the production of a radiation image conversion panel having a layer.

(A) is a schematic front view of an example which utilized the vacuum evaporation system of this invention for the manufacturing apparatus of a radiographic image conversion panel, (B) is the schematic side view. It is a schematic plan view of the heating evaporation part of the manufacturing apparatus shown in FIG. (A), (B), and (C) are the conceptual diagrams for demonstrating conveyance of the board | substrate by the manufacturing apparatus shown in FIG. It is a figure which shows an example of the speed pattern of the reciprocating conveyance of the board | substrate in the manufacturing apparatus shown in FIG. It is a figure which shows notionally the film thickness distribution of the CsBr layer formed with the speed pattern shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Manufacturing apparatus 12 Vacuum chamber 14 Substrate conveyance means 16 Heating evaporation part 18 Gas introduction means 24 Substrate holding means 26 Conveyance means 30 Guide rail 32 Engagement member 34 Screw shaft 36 Nut part 38 Rotation drive source 40 Conveyance control means 42 Base 44 Holding member 50 Crucible 54 First evaporation source row 56 Second evaporation source row

Claims (5)

Evaporation comprising one or more evaporation sources arranged in a direction perpendicular to the reciprocating conveyance direction, disposed under a substrate conveyance position by the conveying means, and a vacuum chamber, a conveying means for linearly reciprocating the substrate A vacuum evaporation apparatus having a heating evaporation section having a source row arranged in the reciprocating conveyance direction and having one or more,
Tmax is the maximum point of the film thickness distribution in the reciprocating conveyance direction, and Tmin is the point at which the film thickness becomes substantially zero, which is obtained when the evaporation is performed with the substrate fixed to the upper part of each evaporation source row. In this case, the transfer means folds the transfer before the rear end in the transfer direction of the substrate reaches the Tmin, which is the most downstream in the transfer direction, and performs the reciprocal transfer of the substrate.   The vacuum deposition apparatus according to claim 1, wherein the transfer unit changes a transfer speed of the substrate during linear transfer except when the substrate is turned back. With the center position in the reciprocating conveyance direction of the substrate as a reference position,
The transport means sets the transport speed of the substrate so that the transport speed of the substrate when the reference position of the substrate passes through the intermediate part of the reciprocating transport is lower than a predetermined transport speed before and after the transport is folded back. The vacuum evaporation system according to claim 2 to be changed. Having two or more vapor deposition source arrays arranged in the reciprocating conveyance direction;
2. The transport means wraps back and transports the substrate when the rear end of the substrate in the transport direction is positioned between the Tmax at the most downstream in the transport direction and the Tmax immediately upstream thereof. 4. The vacuum evaporation apparatus according to any one of 3.   The vacuum evaporation apparatus in any one of Claims 1-4 which form the fluorescent substance layer which consists of stimulable fluorescent substance on the surface of the said board | substrate.

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