JP2009064740A - Deposition method and device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent displacement of a deposition pattern or blurring of an edge due to thermal deformation of a substrate during film forming. <P>SOLUTION: In the deposition device forming a film by relatively moving a substrate 5 as shown in an arrow mark to a deposition source having a plurality of evaporation sources 2, the evaporation source 2a for film-forming at a center region of the substrate 5 is arranged at a downstream side of the evaporation source 2b for filming at end-part regions. Film-forming at the end-part regions of the substrate 5 is made preceded and that at the center part is made last, so that thermal deformation of the substrate end part during the film-forming is alleviated. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a vapor deposition method and a vapor deposition apparatus for forming a vapor deposition film having a desired pattern on a substrate in a vacuum.

  2. Description of the Related Art Conventionally, a thin film forming method for forming a film on a film formation surface of a substrate through a shadow mask (evaporation mask) having a predetermined mask pattern is known.

  Using this method, for example, a display using an organic electroluminescence element (organic EL element) is manufactured. The organic EL display has various advantages such as being self-luminous, not requiring a backlight, excellent in high-speed response, being driven at a low voltage, and being capable of a large screen. Recently, it is spreading to the market as a next-generation display such as a sub-display of a mobile phone, a display of a digital camera and a digital video camera, and an in-vehicle display.

  An organic EL element used for such an organic EL display has a structure in which an organic material is sandwiched between electrodes (anode and cathode) from above and below. Then, holes are injected from the anode into the organic layer made of an organic material, and electrons are injected from the cathode. The holes and electrons are recombined in the organic layer to emit light.

  In general, the organic layer in the organic EL device has 3 to 5 layers such as a hole injection layer, a hole transport layer, a light emitting layer, an electron transport layer, and an electron injection layer. As a method of forming the organic layer, there is a method of forming each layer sequentially by vacuum deposition using a vacuum thin film forming technique to form a laminated structure.

  As means for forming R (red), G (green), and B (blue) pixels of an organic EL display, painting by mask vapor deposition is used. In mask vapor deposition, a vapor deposition mask is brought into close contact with the side on which the substrate film is formed, and an evaporation source is installed at a position away from the side on which the substrate film is formed. In this method, an organic material evaporated from an evaporation source is deposited on a predetermined position of a substrate through a deposition mask and patterned.

  In recent years, substrates have become larger to improve productivity. In order to ensure film thickness uniformity within a large substrate, it has been proposed to arrange evaporation sources at two or more locations. For example, a plurality of evaporation sources are arranged on a straight line parallel to a certain side of the substrate on the bottom surface in the vacuum chamber (see Patent Document 1).

JP-A-2005-19090

  However, when performing vacuum evaporation, the evaporation source becomes high temperature in the process of heating the evaporation source in order to evaporate the organic material from the evaporation source, and this radiation heat causes the evaporation mask and the substrate to rise in temperature, Deform. As described above, when the vapor deposition mask and the substrate are thermally deformed, the positions of the vapor deposition mask and the substrate are shifted, and the pattern of the organic film formed on the substrate is shifted from a desired position.

  In general, the larger the amount of thermal deformation of the vapor deposition mask or the substrate, the larger the positional deviation amount of this pattern. When the amount of pattern misalignment is large, there is a high possibility that display defects such as pixel defects and line defects occur in the organic EL display.

  Since the amount of thermal deformation of the vapor deposition mask and the substrate is determined according to the thermal expansion coefficient specific to the material forming the vapor deposition mask and the substrate, a material having high heat resistance is used as a countermeasure against the thermal deformation of the vapor deposition mask and the substrate. It is possible.

For example, as a material having high heat resistance, an evaporation mask is Invar material, and a substrate is Corning glass. The coefficient of thermal expansion is about 1.6 × 10 ⁻⁶ [° C. ⁻¹ ] for the invar material, and about 3.8 × 10 ⁻⁶ [° C. ⁻¹ ] for the coning glass. Corning glass, which is the material of the substrate, has a larger coefficient of thermal expansion, and therefore a larger amount of thermal deformation.

When the size of one side of the substrate is 1 m and coning glass is used as the material, the thermal expansion coefficient of the coning glass is about 3.8 × 10 ⁻⁶ [° C. ⁻¹ ], and the temperature rise of the substrate is 5 ° C. The amount of deformation of the substrate is about 19 μm. When the amount of positional deviation of the organic film pattern at this time is estimated, when the center of the substrate is used as a reference point, the amount of positional deviation is about 9.5 μm at the edge of the substrate.

  On the other hand, the length of one side of a pixel in a high-definition organic EL display is 10 μm to 200 μm, and these pixels are regularly arranged at intervals of 10 μm to 50 μm. Therefore, in order to obtain an organic EL panel having a high definition and a high aperture ratio, it is desirable that the amount of positional deviation of the organic film pattern is about 10 μm or less.

  Factors of the positional deviation amount of the organic film pattern include the production accuracy of the vapor deposition mask, the substrate shape variation, the alignment accuracy between the vapor deposition mask and the substrate, the positional deviation due to thermal deformation of the vapor deposition mask and the substrate, and the like. For this reason, it is desirable that the amount of positional deviation due to thermal deformation is about 5 μm or less.

  An object of the present invention is to provide a vapor deposition method and a vapor deposition apparatus that can suppress thermal deformation of a substrate during film formation and can accurately form a vapor deposition film at a deposition position on the substrate. is there.

  The vapor deposition method of the present invention includes a film forming step of forming a film on the film formation substrate through a vapor deposition mask using a plurality of evaporation sources while moving the film formation substrate relative to the evaporation source. In addition, the remaining region excluding the central region is formed in advance from the central region of the deposition target substrate extending in the relative movement direction.

  The vapor deposition apparatus of the present invention includes a vacuum chamber, a first evaporation source for forming a film in a central region of the film formation substrate in the vacuum chamber, and the film formation substrate in the vacuum chamber. A second evaporation source for forming a film in the remaining region excluding the central region; and a transport unit for moving the deposition target substrate relative to the first and second evaporation sources. The first evaporation source is arranged downstream of the second evaporation source in the relative movement direction.

  In a film formation process for forming a vapor deposition film on a deposition target substrate (substrate), a film is formed first at an end portion of the substrate, and then a central region including a central portion of the substrate is formed.

  When the film is formed near the edge of the substrate, the amount of deformation is not integrated because the temperature rise at the center of the substrate is small, and the amount of thermal deformation at the edge of the substrate can be greatly reduced. Thereby, it is possible to prevent positional deviation of the vapor deposition pattern and blurring of the edge due to thermal deformation, and it is possible to accurately form a vapor deposition film at a desired position on the substrate.

  Further, by providing a shielding means (heat shield plate) around the evaporation source, radiant heat from the evaporation source can be suppressed, and an increase in the temperature of the substrate in the film formation process can be reduced. Further, by cooling the heat shield plate, radiant heat from the evaporation source can be further suppressed.

  An embodiment of the present invention will be described with reference to the drawings.

  First, a schematic configuration of the organic EL element will be described. An organic EL element is formed on a substrate (deposition substrate) for constituting an organic EL display, and a plurality of organic layers (evaporated films) made of different organic materials are sequentially stacked. . On the substrate, a plurality of organic EL elements corresponding to R, G, and B color components are arranged in a matrix according to a predetermined pattern.

  The arrangement of each organic EL element for displaying a color image can be realized by forming each organic EL element by patterning film formation corresponding to each color component of R, G, and B. The patterning film formation is performed using a vapor deposition mask made of a magnetic material (magnetic material) such as iron, nickel, or invar. The vapor deposition mask is provided with a plurality of openings corresponding to a predetermined vapor deposition pattern.

  The vapor deposition mask is closely attached so as to cover one surface side of the substrate that is the deposition target substrate. At this time, a magnetic member is disposed on the other surface side of the substrate. Due to the magnetic force of the magnetic member, the adhesion between the vapor deposition mask and the substrate is strengthened, and the positional deviation between the substrate and the mask after alignment can be suppressed. In this manner, a predetermined pattern can be formed on the substrate by using the vapor deposition mask. If a plurality of types of vapor deposition masks are prepared, multilayer film formation with different patterns can be performed, and a plurality of organic EL elements can be arranged in a matrix.

  Next, a manufacturing system for forming an organic EL element on the substrate as described above to constitute an organic EL display will be described. In order to construct an organic EL display capable of displaying a color image, this manufacturing system performs patterning film formation corresponding to each color component of R, G, B, and a plurality of organic EL elements on a substrate in a matrix form It is for arranging.

  The manufacturing system to which this embodiment is applied has a substrate supply unit to which a substrate is supplied from the outside, and a preprocessing unit that performs preprocessing such as cleaning and activation on the substrate. In addition, an R color alignment unit that performs alignment corresponding to the R color, an R color film formation unit that performs patterning film formation corresponding to the R color, a G color alignment unit that performs alignment corresponding to the G color, and a G color And a G-color film forming unit that performs corresponding patterning film formation. Furthermore, a B color alignment unit that performs alignment corresponding to B color, a B color film formation unit that performs patterning film formation corresponding to B color, and a post-processing unit that performs post-processing such as separation of the substrate and the vapor deposition mask Have. In addition, a substrate discharge unit is provided for discharging the substrate after the organic EL elements corresponding to the respective colors are formed by patterning film formation.

  Among these units, the R color film forming unit, the G color film forming unit, and the B color film forming unit correspond to the vapor deposition apparatus of the present embodiment.

  The temperature rise of the substrate in the film formation process is caused by the fact that a plurality of evaporation sources that are high in temperature for heating the vapor deposition material are arranged at positions facing a plurality of regions of the substrate. Occur. In particular, the temperature rise at the location facing the evaporation source is increased.

  In a general film forming process, the substrate is supported on one side by a vapor deposition mask and a frame of the vapor deposition mask and on the other side by a metal plate. In this state, the contact between the substrate and the vapor deposition mask, the frame of the vapor deposition mask, and the metal plate is almost uniform. Therefore, the substrate is supported with a substantially uniform frictional force.

  When the temperature of the substrate rises in this supporting state, the substrate is thermally deformed with the center of the substrate as a base point. That is, the amount of deformation is integrated from the center of the substrate to the end, and the thermal deformation at the end of the substrate becomes the largest. The thermal deformation at the end of the substrate is further increased because the amount of deformation to be integrated increases as the substrate increases. However, if the central portion of the substrate does not rise in temperature and there is no thermal deformation, the amount of deformation is not integrated, and the amount of thermal deformation at the end of the substrate can be greatly reduced.

  In the vapor deposition apparatus according to the present embodiment, an evaporation source group composed of a plurality of evaporation sources for forming the same material in a vacuum chamber is arranged, and the vapor deposition mask is aligned with the substrate by a separately provided alignment apparatus. And conveying means for integrating and moving on the evaporation source group. This transport means may have another configuration such as moving the evaporation source group side as long as the evaporation source group in the vacuum chamber is moved relative to the substrate and the vapor deposition mask.

  As shown in FIGS. 1A and 1B, the vapor deposition apparatus according to the present embodiment includes a vacuum chamber 1 and a plurality of evaporation sources 2 (2a, 2b) arranged on the bottom surface of the vacuum chamber 1. . Further, the heat shield plate 4 which is a shielding means for shielding the radiant heat generated when the vapor deposition material 3 of each evaporation source 2 is heated, the substrate 5 which is a film formation substrate, and each evaporation source 2 are relatively moved. And a conveying means (not shown). The vacuum chamber 1 includes a carry-in port and a discharge port for the substrate 5 and the vapor deposition mask 6.

  Each evaporation source 2 contains a vapor deposition material 3 which is the same organic material corresponding to the organic layer formed on the substrate. As shown in FIG. 1, here, a case where three evaporation sources 2 are installed will be described. With this configuration, the first evaporation source 2a for forming the vapor deposition film in the central region including the central portion of the substrate 5 and extending in the direction of relative movement is arranged on the downstream side (relative movement) of the substrate 5 in the transport direction indicated by the arrow. (Ie, on the downstream side in the direction), that is, at the position farthest from the substrate 5 at the start of film formation.

  As described above, when the first evaporation source 2a to be formed in the central region of the substrate 5 is disposed at a position farthest from the substrate 5, the remaining region of the substrate 5 precedes the film formation in the central region of the substrate 5. The vapor deposition is performed by the second evaporation source 2b corresponding to the end region. As described above, when the remaining region is deposited by the second evaporation source 2b prior to the deposition of the central region, the temperature rise in the central portion of the substrate 5 is very small when the vicinity of the end of the substrate 5 is deposited. Therefore, the deformation amount is not integrated, and the heat deformation amount at the end of the substrate 5 can be greatly reduced. As a result, it is possible to prevent deposition pattern misalignment and edge blurring due to thermal deformation, and to provide a high-definition organic EL element by accurately forming an organic film at a desired position on a substrate. Can do.

  Here, a case where the number of installed evaporation sources is three is given as an example, but the present invention is not limited to this. The arrangement of the evaporation sources in the case where the number of evaporation sources is three or more is the same, and the evaporation source for depositing the film formation region (central region) in the vicinity of the central portion of the substrate is arranged at a position farthest from the substrate. Then, the evaporation source corresponding to the vapor deposition region is sequentially arranged in the order in which the film formation region on the substrate is directed from the center to the end.

  Each evaporation source evaporates the organic material, for example, by heating a heater, and an independent temperature controller is connected to each evaporation source, and the film thickness is monitored by a film thickness sensor. Is kept stable. That is, the evaporation rate of each evaporation source is individually controlled by the temperature controller and the film thickness sensor.

  In addition, by reducing the emissivity of the surface of the surface of the evaporation source facing the substrate by a process such as polishing, radiation heat from the evaporation source is less likely to be transmitted to the substrate, and the temperature rise of the substrate is reduced. be able to.

  A heat shield is provided around the evaporation source so as not to block the opening of the evaporation source. By providing the heat shield plate, it is possible to suppress radiant heat from the evaporation source and reduce the temperature rise of the substrate. Furthermore, by providing means for cooling the heat shield plate, the effect of suppressing radiant heat from the evaporation source can be increased.

  As a transfer means for moving the substrate and the vapor deposition mask relative to each other during the film forming process, a transfer method using a ball screw or a belt conveyor, which is a countermeasure against degassing, is used.

  Next, the manufacturing method of an organic EL element is demonstrated.

  In forming an organic EL element on a substrate, first, precise alignment between the substrate and the vapor deposition mask is performed in an R color alignment unit, a G color alignment unit, or a B color alignment unit. This precise alignment is performed by detecting and recognizing alignment marks on the substrate and the vapor deposition mask by image processing or the like.

  After the alignment, the substrate and the vapor deposition mask are brought into close contact with each other by the magnetic force of the magnetic member installed on the back surface of the substrate. Then, it is conveyed from the carry-in entrance into the vacuum chamber of the present invention by a handling robot, a conveyer or the like.

  The substrate and the vapor deposition mask that have been transferred into the vacuum chamber are transferred so that the deposition position of the substrate sequentially passes through the position facing each evaporation source. At this time, the evaporation rate of each evaporation source is individually controlled by a temperature controller or the like while following a preset setting.

  As described above, the evaporation source is disposed at the position farthest away from the substrate in the substrate transport direction, and the film forming process near the center of the substrate is performed last. To be For this reason, when the vicinity of the edge of the substrate is deposited, the amount of deformation is not integrated because the temperature rise at the center of the substrate is minute, and the amount of thermal deformation at the edge of the substrate can be greatly reduced. As a result, it is possible to prevent deposition pattern misalignment and edge blurring due to thermal deformation, and to provide a high-definition organic EL element by accurately forming an organic film at a desired position on a substrate. Can do.

  In this way, the substrate and the vapor deposition mask pass over each evaporation source, and the substrate and the vapor deposition mask after film formation are carried out of the vacuum chamber from the carry-out port by a handling robot, a conveyance conveyor, or the like. And it is sent to the vapor deposition apparatus corresponding to the following color component, and the same alignment and film-forming process are performed again. By repeating this, an organic EL element corresponding to each color component of R, G, and B is formed on the substrate.

  The present invention is not limited to the manufacturing process of the organic EL element, and can be applied to various film forming processes.

The structure of the vapor deposition apparatus by one Embodiment is shown, (a) is the top view, (b) is a side view.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Vacuum chamber 2, 2a, 2b Evaporation source 3 Vapor deposition material 4 Heat shield plate 5 Substrate 6 Vapor deposition mask

Claims (6)

Using a plurality of evaporation sources, and having a film formation step of forming a film on the film formation substrate through an evaporation mask while moving the film formation substrate relative to the evaporation source;
The vapor deposition method is characterized in that the deposition of the remaining region excluding the central region is performed in advance of the central region of the deposition target substrate extending in the relative movement direction.   The vapor deposition method according to claim 1, wherein a plurality of vapor deposition films are stacked by repeating the film forming step. A vacuum chamber;
A first evaporation source for forming a film in a central region of the deposition target substrate in the vacuum chamber;
A second evaporation source for forming a film in the remaining region excluding the central region of the deposition target substrate in the vacuum chamber;
Transport means for moving the deposition target substrate relative to the first and second evaporation sources,
The vapor deposition apparatus, wherein the first evaporation source is disposed downstream of the second evaporation source in the relative movement direction.   The vapor deposition apparatus according to claim 3, wherein the periphery of each evaporation source is covered with a shielding means.   The vapor deposition apparatus according to claim 4, further comprising means for cooling the shielding means.   The vapor deposition apparatus according to claim 3, wherein the vapor deposition mask is formed of a magnetic material, and a magnetic member is installed on the deposition target substrate.

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