JP2010080439A - Donor substrate for transfer, and method for manufacturing device using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a patterning method that enables the large-sized and accurate fine patterning without degrading the characteristics of thin films including an organic EL material and the like, and to provide a method for manufacturing a device using such a patterning method. <P>SOLUTION: A photothermal conversion layer is formed on a substrate, and a partition pattern is formed on the photothermal conversion layer. The donor substrate where a transfer material exists within the partition pattern is arranged in opposition to a device substrate, and the light is irradiated to the photothermal conversion layer so that at least a part of the transfer material and at least a part of the partition pattern may be heated at the same time, thereby transferring the transfer material to the device substrate. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a donor substrate for transfer used for patterning a device including an organic EL element, and a device manufacturing method using the same.

  In the organic EL element, electrons injected from a cathode and holes injected from an anode are recombined in an organic light emitting layer sandwiched between both electrodes. Kodak's C.I. W. Since Tang et al. Have shown that organic EL devices emit light with high brightness (see Non-Patent Document 1), many research institutions have studied.

  This light-emitting element is thin and has high luminance light emission under a low driving voltage, and various organic materials are used for the light-emitting layer, so that the three primary colors of red (R), green (G), and blue (B) are used. Therefore, practical use as a color display is progressing. For example, FIG. 9 illustrates a configuration of the organic EL element. An organic EL element (device substrate) 10 includes a support 11, a TFT (including extraction electrode) 12 formed thereon, a planarization film 13, an insulating layer 14, a first electrode 15, a hole transport layer 16, and a light emitting layer. 17R, 17G, 17B, an electron transport layer 18, and a second electrode 19. In this active matrix color display, a technique for patterning at least the light emitting layers 17R, 17G, and 17B with high accuracy is required. Moreover, in order to realize a high-performance organic EL device, a multilayer structure is required, and a hole injection layer, a hole transport layer, a light-emitting layer, an electron transport layer, an electron having a typical film thickness of 0.1 μm or less It is necessary to sequentially stack an injection layer and the like.

  Conventionally, wet processes such as a photolithography method, an inkjet method, and a printing method have been used for fine patterning of a thin film. However, in the wet process, it is difficult to completely prevent changes in the shape or undesirable mixing of the extremely thin underlayer when applying photoresist or ink on the previously formed underlayer. The materials that can be used are limited. In addition, it is difficult to achieve film thickness uniformity within a pixel of a thin film formed by drying from a solution and between pixels within a substrate, and current concentration and element deterioration due to film thickness unevenness occur. In addition, there is a problem that the performance as a display is lowered.

  As a patterning method by a dry process that does not use a wet process, a mask vapor deposition method has been studied. The light emitting layer of a small organic EL display which is actually put into practical use is exclusively patterned by this method. However, since the deposition mask needs to make a precise hole in the metal plate, it is difficult to achieve both large size and accuracy, and as the size increases, the adhesion between the substrate and the deposition mask tends to be impaired. Therefore, application to a large organic EL display has been difficult.

  As a method of patterning a large substrate by a dry process, a method of patterning an organic EL material in advance on a film and transferring the patterned organic EL material to a device substrate has been proposed (Patent Document 1). . This is a method in which a film formed with an organic EL material (referred to as a “donor substrate”) is closely attached to a device substrate, and the donor substrate is heated to transfer the organic EL material to the device substrate.

  Furthermore, a partition pattern is formed on the donor substrate with partition walls, and the organic EL material disposed in the partition pattern is placed opposite to the device substrate with a gap, and the entire donor substrate is heated with a hot plate, An evaporation transfer method in which an organic EL material is evaporated and deposited on a device substrate has also been proposed (see Patent Document 2).

  However, in the above method, since the entire donor substrate is heated and thermally expanded, the relative position of the organic EL material patterned on the donor substrate with respect to the device substrate is displaced. Moreover, since the displacement amount increases as the size increases, the problem that high-precision patterning is difficult is developed. Furthermore, there is a problem that the device performance deteriorates because the device substrate opposed at a short distance is heated by radiation or has a partition pattern, which is affected by degassing from the partition pattern. It was.

  As a method for preventing displacement due to thermal expansion of the donor substrate, there is a proposal of a donor substrate in which a photothermal conversion layer is formed on the donor substrate and an organic EL material is formed on the entire surface by thermal evaporation. This donor substrate is formed on the entire surface using heat generated by partially irradiating the photothermal conversion layer with a high-intensity laser, or R, G, and B are separately applied without using a partition pattern. It is used in a selective transfer method in which a part of a material is pattern transferred onto a device substrate (see Patent Documents 3 to 4).

  However, in this transfer method, the generated heat is diffused also in the lateral direction of the donor substrate, so that the organic EL material in a region wider than the laser irradiation range is transferred, and the boundary is not clear. In order to prevent this, it is conceivable to irradiate a high-intensity laser in an extremely short time. However, in this case, since the organic EL material is heated in an extremely short time, it is difficult to accurately control the maximum temperature. Therefore, there is a problem that the probability that the organic EL material reaches the decomposition temperature or higher is increased, and as a result, the device performance is deteriorated.

  As another method for preventing displacement due to thermal expansion of the donor substrate, a direct heating transfer method is disclosed in which the organic EL material on the donor substrate is directly heated with a laser without forming a photothermal conversion layer on the donor substrate (patent). Reference 5). In Patent Document 5, the possibility of color mixing at the time of patterning is further reduced by separately coating R, G, and B with partition patterns.

  However, since the typical film thickness of the organic EL material is very thin at 25 nm, there is a problem that the laser reaches the device substrate without being sufficiently absorbed and heats the underlying layer on the device substrate. A high-intensity laser is required to perform sufficient transfer. However, since the partition pattern deteriorates when the partition pattern is irradiated with the laser, only the organic EL material is irradiated with the laser to prevent the deterioration. However, there is a problem that high-precision positioning is required and it is difficult to increase the size.

JP 2002-260854 A JP 2000-195665 A Japanese Patent No. 3789991 JP 2005-149823 A JP 2004-87143 A

“Applied Physics Letters” (USA), 1987, 51, 12, 913-915.

  As described above, in the prior art, it has been difficult to stably achieve fine patterning without damaging the organic EL material while achieving both large size and high accuracy. In particular, using the laser transfer method with the partition pattern disposed on the donor substrate has problems such as deterioration of the partition pattern, degassing, and induction of temperature unevenness of the transfer material.

  An object of the present invention is to solve this problem and to provide a donor substrate for transfer that can be increased in size and finely patterned without degrading the characteristics of devices such as organic EL elements.

  That is, the present invention includes a substrate, a photothermal conversion layer formed on the substrate, a partition pattern at least partially formed on the upper surface of the photothermal conversion layer, and a transfer layer formed in the partition pattern. This is a donor substrate for transfer.

  According to the present invention, there is an effect that large-scale and high-precision fine patterning is possible without damaging a thin film including an organic EL material and without performing high-precision alignment.

Sectional drawing which shows an example of the donor substrate by this invention. It is a figure which shows the donor substrate of this invention in which the transfer auxiliary layer was formed. It is a top view which shows a donor substrate in case the division pattern is wider than the width | variety of a transfer layer with the donor substrate of this invention. It is a figure which shows a mode when the transcription | transfer layer becomes relatively the same as a division pattern in the donor substrate of this invention. The perspective view of the donor substrate of this invention It is a figure which shows an example of the material which can be utilized for the transfer using the donor substrate of this invention. It is a figure which shows a mode that it transfers using the donor substrate of this invention. It is the figure which showed a mode that a laser was scanned when transferring using the donor substrate of this invention. It is a figure which shows an example of an organic EL element.

  FIG. 1 shows the configuration of the donor substrate of the present invention. Referring to FIG. 1, donor substrate 30 includes support 31, photothermal conversion layer 33, partition pattern 34, and transfer material 37 (coating film for each RGB light emitting material of organic EL) present in the partition pattern.

  The support 31 is not particularly limited as long as it has a low light absorption rate and can stably form a photothermal conversion layer, a partition pattern, and a transfer material thereon. It is also possible to use a resin film. Specific resin materials include polyester, polyethylene, polyethylene terephthalate, polyethylene naphthalate, polycarbonate, polyacryl, polysulfone, polyethersulfone, polyphenylene sulfide, polyimide, polyamide, polybenzoxazole, polyepoxy, polypropylene, polyolefin, and aramid. Resin, silicone resin, etc. can be used.

  As a preferable support in terms of chemical / thermal stability, dimensional stability, mechanical strength, and transparency, a glass plate can be exemplified. It can be appropriately selected from soda lime glass, alkali-free glass, lead-containing glass, borosilicate glass, aluminosilicate glass, low expansion glass, quartz glass and the like. When the transfer process of the present invention is carried out in vacuum, a glass plate is a particularly preferred support because it is required that gas release from the support is small.

  Even if the photothermal conversion layer 33 is heated to a high temperature, it is necessary to keep the temperature rise (thermal expansion) of the support itself within an allowable range. Therefore, the heat capacity of the support is preferably sufficiently larger than that of the photothermal conversion layer. Therefore, the thickness of the support is preferably 10 times or more the thickness of the photothermal conversion layer. Although the allowable range of thermal expansion depends on the size of the transfer region and the required accuracy of patterning, for example, the allowable range of thermal expansion is not shown, but for example, the photothermal conversion layer rises from room temperature by 300 ° C. When it is desired to suppress the temperature to 3 ° C. or less, which is 100, the thickness of the support is preferably 100 times or more the thickness of the photothermal conversion layer, and the temperature rise of the support is 1/300 of 300 ° C. 1 When it is desired to suppress the temperature to below ° C., the thickness of the support is preferably 300 times or more the thickness of the photothermal conversion layer. By doing in this way, even if it enlarges, the amount of dimensional displacement by thermal expansion is small, and highly accurate patterning is attained.

  The photothermal conversion layer 33 is a layer formed on the support 31 and is not particularly limited as long as it is a material / configuration that efficiently absorbs light to generate heat and is stable against the generated heat. However, it is desirable that the heat capacity be large in order to prevent a rapid temperature rise and prevent a local temperature drop due to thermal diffusion to the partition pattern.

This is because if the heat capacity is small, the transfer material cannot be transferred slowly because it is easy to heat and cool. The heat capacity is a product of volume and volume specific heat, and a material having a large volume specific heat is desirable. Specifically, the volume specific heat of the photothermal conversion layer 33 is preferably 2 J / cm ³ K or more. Further, a larger heat conductivity of the photothermal conversion layer 33 is more desirable because uniform heating is possible and local temperature decrease is reduced. Specifically, the thermal conductivity of the photothermal conversion layer 33 is preferably 50 W / mK or more. Here, in the case where the photothermal conversion layer 33 is made of a plurality of layers or alloys of different materials, the thermal conductivity and the volume specific heat are values of the entire photothermal conversion layer. As the overall value, in the case of a plurality of laminated thin films made of different materials, a calculated value obtained by weighting and averaging the values of the thermal conductivity and volume specific heat of the material alone with the respective film thicknesses is used. When calculation is difficult like an alloy, it can be measured by a known method such as a laser flash method, a scanning laser AC heating method, a differential method, or a 3ω method.

  As such a material, a thin film in which carbon black, graphite, titanium black, an organic pigment, metal particles, or the like is dispersed in a resin can be used. Moreover, in this invention, since a photothermal conversion layer may be heated at about 300 degreeC, it is preferable that a photothermal conversion layer consists of an inorganic thin film which is excellent in heat resistance, and has high heat conductivity and volume specific heat. Therefore, it is particularly preferable to use a metal thin film in terms of light absorption and film formability. Specifically, as a metal material, tungsten, tantalum, molybdenum, titanium, chromium, gold, silver, copper, platinum, iron, zinc, aluminum, cobalt, nickel, magnesium, vanadium, zirconium, silicon, carbon, etc. Or a thin film of an alloy or a laminated thin film thereof can be used.

  Among the above, it is desirable that the photothermal conversion layer 33 be made of a metal that is stable against chemical reaction. This is because, if at least the outermost surface is a stable metal, the emissivity of the outermost surface can be kept low, so that damage on the device substrate side due to heat can be reduced. In addition, if a reactive metal is used, residues in the process of the partition pattern are likely to remain and are transferred as impurities to the light emitting layer, which may cause a significant decrease in luminance. Examples of metals that form a stable thin passive layer by natural oxidation include metals of group 5, namely vanadium, niobium, and tantalum. Examples of noble metals whose surfaces are not oxidized include gold, silver, platinum, palladium, rhodium, iridium, ruthenium, and osmium. It is desirable to use these group 5 metals and noble metals for the photothermal conversion layer 33. In addition, a material that easily absorbs laser is formed on the support side by using a plurality of layers of light-to-heat conversion layers by sputtering, and a stable metal is formed on the outermost surface by sputtering to protect the inside. It is also possible to improve the photothermal conversion efficiency of the laser. The material of the layers other than the surface is not particularly limited, but chromium, molybdenum, and the like can be exemplified as preferable materials in consideration of film formation ease and cost (patterning properties as required).

  Of the Group 5 metals, tantalum and niobium have a thermal conductivity of 50 W / mK or more, which is more desirable because local temperature reduction is reduced. Furthermore, tantalum has a very stable passive layer on the surface and is not affected by acids and alkalis other than hydrofluoric acid. For this reason, when the photothermal conversion layer is heated to a high temperature by irradiating a laser, the oxidation of the surface is difficult to proceed, which is good for stabilizing the surface. When the surface reactivity is reduced, the substrate surface is also excellent in acid resistance and alkali resistance, so the number of times of repeated use by the cleaning process of the donor substrate through the organic cleaning process, the alkali cleaning process, and the acid cleaning process is improved. However, it is particularly desirable to use tantalum because of its excellent recyclability.

In addition, when a solution composed of a transfer material and a solvent is applied to the light-to-heat conversion layer as described later, the solution may repel. As a countermeasure against this phenomenon, there is a case where it can be avoided by a method of providing irregularities on the surface of the photothermal conversion layer. In particular, as a method for forming irregularities on the surface of tantalum having an extremely stable surface, there are a wet etching method using a chemical solution such as hydrofluoric acid and ammonium fluoride, a dry etching method using CF ₄ plasma, and the like.

  If necessary, an antireflection layer can be formed on the support 31 side of the photothermal conversion layer 33. Further, an antireflection layer may be formed on the surface of the support 31 on the light incident side. These anti-reflection layers are preferably optical interference thin films that use the difference in refractive index, and simple or mixed thin films such as silicon, silicon oxide, silicon nitride, zinc oxide, magnesium oxide, and titanium oxide, and laminated thin films thereof are used. it can.

  If necessary, a transfer auxiliary layer can be formed on the photothermal conversion layer 33 on the transfer material 37 side. An example of the function of the transfer auxiliary layer is a function of preventing the transfer material from being deteriorated by the catalytic effect of the heated photothermal conversion layer, and is an inert inorganic material such as tungsten, tantalum, molybdenum, silicon, oxide, or nitride. A thin film can be used. Another example of the function of the transfer auxiliary layer is a surface modification function when a transfer material is formed by a coating method, such as the rough surface thin film of the illustrated inert inorganic thin film or the porous film of the metal oxide. Can be used.

  Another example of the function of the transfer auxiliary layer is the uniform heating of the transfer material. For example, as shown in FIG. 2A, in order to uniformly heat the relatively thick transfer material 37, the heat transfer conductivity is increased. The transfer auxiliary layer 39 having a spike-like (or porous) structure can be formed by using an excellent material such as a metal, and the transfer material 37 can be arranged so as to be supported in the gap. The transfer auxiliary layer having this function may be integrated with the photothermal conversion layer 33 as shown in FIG.

  Since the light-to-heat conversion layer needs to provide sufficient heat for evaporation of the transfer material, it is preferable that the heat capacity of the light-to-heat conversion layer is greater than that of the transfer material. Therefore, the thickness of the photothermal conversion layer is preferably thicker than the transfer material, and more preferably 5 times or more the thickness of the transfer material. The numerical value is preferably 0.02 to 2 μm, more preferably 0.1 to 1 μm. In order to avoid a sudden temperature rise or a temperature drop near the partition pattern, it is particularly preferably 0.2 μm or more.

  Further, since the photothermal conversion layer preferably absorbs 90% or more of light, and more preferably 95% or more, it is preferable to design the thickness of the photothermal conversion layer so as to satisfy these conditions. When the transfer auxiliary layer is provided, it is preferable to design the transfer auxiliary layer so that the heat generated in the light-to-heat conversion layer is thin enough to satisfy the required function so as not to prevent the heat from being efficiently transferred to the transfer material.

  If the photothermal conversion layer 33 is formed in a portion where the transfer material exists, the planar shape is not particularly limited. For example, even if it is formed on the entire surface of the donor substrate as illustrated above, It may be patterned so as to be discontinuous. When the partition pattern has poor adhesion to the photothermal conversion layer, the adhesion can be improved by utilizing the adhesion to the support in this manner. In addition, the code | symbol 35 of FIG. 2 illustrates such a division pattern.

  When the light-to-heat conversion layer is patterned, it is not necessary to have the same type of shape as the partition pattern, and the partition pattern may have a lattice shape and the light-to-heat conversion layer may have a stripe shape. Since the photothermal conversion layer 33 has a high light absorption rate, it is preferable to form the position mark of the donor substrate using the photothermal conversion layer. The position of the donor substrate can be detected optically, and alignment of the donor substrate and the device substrate during transfer can be performed more easily.

  As a method for forming the photothermal conversion layer and the transfer auxiliary layer, a known technique such as spin coating, slit coating, vacuum deposition, EB deposition, sputtering, ion plating, or the like can be used. When patterning, a known photolithography method, laser ablation, or the like can be used.

  Referring to FIG. 1 again, the partition pattern 34 is not particularly limited as long as it is a material / configuration that defines the boundary of the transfer material and is stable against the heat generated in the photothermal conversion layer 33. For inorganic substances, oxides / nitrides such as silicon oxide and silicon nitride, glass, ceramics and the like can be used, and for organic substances, resins such as polyvinyl, polyimide, polybenzoxazole, polystyrene, acrylic, novolac, and silicone can be used. The well-known technique which manufactures the partition in a plasma television by the glass paste method can also be used. The thermal conductivity of the partition pattern is not particularly limited, but from the viewpoint of preventing heat from diffusing to the device substrate facing through the partition pattern, it is preferable that the thermal conductivity is as small as an organic substance. Further, in consideration of patterning characteristics and heat resistance, it is preferable to use polyimide and polybenzoxazole.

  Without the partition pattern, the RGB organic EL material layers are in contact with each other, and the boundary is not uniform, and a mixed portion is formed at least. In order to prevent this, if a gap is formed so as not to contact each other, it is difficult to make the film thickness of the boundary region the same as the center. In any case, since this boundary region cannot be transferred because it causes a reduction in device performance, it is necessary to selectively transfer a region narrower than the organic EL material pattern on the donor substrate. Accordingly, the width of the organic EL material that can actually be used is narrowed, and when an organic EL display is manufactured, the pixel has a small aperture ratio (the area of the non-light-emitting region is large).

  If transfer must be performed excluding the boundary region, batch transfer cannot be performed with a plurality of transfer materials as one unit. Therefore, R, G, and B must be sequentially irradiated with lasers to transfer them independently. In other words, high-accuracy alignment with high-intensity laser irradiation is required. This leads to an increase in the number of man-hours for the transfer work.

  On the other hand, forming a partition pattern which is a foreign substance other than the transfer material on the donor substrate is originally because the partition pattern itself may be peeled off and transferred, or impurities may be mixed into the transfer material from the partition pattern. It is not preferable. In addition, in a method in which a transfer material is heated to a relatively high temperature, such as a vapor deposition transfer method in which a photothermal conversion layer is installed on a donor substrate to absorb light and the transfer material is transferred by generated heat, There was no precedent for the high possibility of deteriorating performance.

  However, the present invention enables high-definition patterning without requiring high-definition alignment by using a donor substrate provided with a photothermal conversion layer. That is, when such a donor substrate is used, a temperature drop at the boundary between the partition pattern and the transfer material is suppressed when light is irradiated so as to heat the partition pattern simultaneously with the transfer material. The material can also be transferred with sufficient heating. Therefore, since the film thickness distribution of the transfer thin film is made more uniform than before, adverse effects on device performance can be prevented. It was also found that the intensity of light used in the present invention can be reduced. For this reason, even when light is applied so that the transfer material and the partition pattern are heated at the same time, adverse effects on device performance due to separation of the partition pattern and degassing of the partition pattern can be minimized. .

  The method for forming the partition pattern 34 is not particularly limited, and known techniques such as vacuum deposition, EB deposition, sputtering, ion plating, CVD, and laser ablation are used when an inorganic substance is used, and spin coating is used when an organic substance is used. Well-known techniques such as slit coating and dip coating can be used. The patterning method of the partition pattern is not particularly limited, and a known photolithography method can be used. The partition pattern may be patterned by an etching (or lift-off) method using a photoresist, or patterning is performed by directly exposing and developing the partition pattern using a material obtained by adding photosensitivity to the exemplified resin material. May be. Furthermore, a stamp method or an imprint method in which a mold is pressed against the partition pattern layer formed on the entire surface, an ink jet method or a nozzle jet method in which a resin material is directly formed by patterning, and various printing methods can be used.

  The shape of the partition pattern 34 is not limited to the lattice (matrix) structure already illustrated, but for example, as illustrated in FIG. 1, three types of transfer materials 37R, 37G, When 37B is formed, the planar shape of the partition pattern 34 may be a stripe extending in the y direction. In addition, as shown in FIG. 3, a partition pattern 34 wider than the transfer material 37 can be formed. This is because one color is transferred for each of the three colors R, G, and B.

  In this case, three donor substrates 30 on which three kinds of transfer materials 37R, 37G, and 37B are formed are prepared, and the transfer process according to the present invention is performed three times by facing each device substrate. By repeating, the transfer materials 37R, 37G, and 37B can be patterned on one device substrate. This is an example of an effective shape in high-definition patterning that requires a small pitch or gap between the transfer materials 37R, 37G, and 37B.

  The thickness of the partition pattern is not particularly limited. FIG. 4 shows each arrangement when the device substrate 20 is opposed to the donor substrate 30 and the transfer material 37 is blown from the donor substrate. As shown in FIG. 4, even if the partition pattern 34 is the same thickness as the transfer material 37 or thin, if the gap between the donor substrate 30 and the device substrate 20 is maintained, the transfer material evaporated at the time of transfer is slightly spread and supported. Since it is only deposited on the body 21, transfer can be performed without causing mixing between the transfer films 27R, 27G, and 27B.

  The transfer material is preferably not in direct contact with the device substrate, and the gap between the donor substrate and the device substrate is preferably kept in the range of 1 to 100 μm, more preferably 2 to 20 μm. It is preferable that the thickness is greater than the thickness and is 1 to 100 μm, more preferably 2 to 20 μm. By making the partition pattern having such a thickness face the device substrate, the gap between the donor substrate and the device substrate can be easily maintained at a constant value, and the evaporated transfer material enters the other partition. The possibility can be reduced.

  As illustrated in FIG. 9, when a pattern such as the insulating layer 14 is present on the device substrate 10, the width of the insulating layer 14 (particularly the upper width) is larger than the width of the partition pattern 34 (particularly the upper width). ) Is preferably wider. Further, at the time of alignment, it is preferable to arrange so that the width of the upper portion of the insulating layer 14 is within the width of the upper portion of the partition pattern 34. In this case, even if the partition pattern 34 is thin, the donor substrate 30 and the device substrate 10 can be held in a desired gap by increasing the thickness of the insulating layer 14. The typical width of the partition pattern is 5 to 50 μm and the pitch is 25 to 300 μm. However, the partition pattern may be designed to an optimum value depending on the application, and is not particularly limited.

  The sectional shape of the partition pattern is preferably a forward tapered shape in order to facilitate the evaporation transfer material to be uniformly deposited on the device substrate. Here, the “forward taper shape” refers to a shape in which the cross-sectional width 67 on the photothermal conversion layer side is longer than the width 66 on the upper surface side. FIG. 5 shows a part of the donor substrate in a perspective view. A photothermal conversion layer 33 is formed on the substrate 31, and the photothermal conversion layer 33 is formed. The partition pattern 34 has a trapezoidal cross section, and the cross section width 67 is longer than the upper surface side width 66. Reference numeral 60 denotes the height of the partition pattern.

  When using the coating method described later when placing the transfer material in the partition pattern, the upper surface of the partition pattern is used to prevent the solution from being mixed into other partitions or riding on the upper surface of the partition pattern. 61 can be subjected to a liquid repellent treatment (surface energy control). As the liquid repellent treatment, a liquid repellent material such as a fluorine-based material can be mixed with a resin material for forming a partition pattern, or a high concentration region of the liquid repellent material can be selectively formed on the surface or the upper surface. The portion subjected to the liquid repellent treatment is called a liquid repellent layer 64. In FIG. 5, the liquid repellent layer is indicated by oblique lines and is shown on a part of the upper surface of the pattern.

  The partition pattern can be a multilayer structure of materials having different surface energies, and a known technique such as controlling the surface energy state by performing light irradiation or plasma treatment with a fluorine-containing material-containing gas after the partition pattern is formed. Can be used.

  The transfer layer 37 is a layer made of an organic EL element material exhibiting each color. The transfer material may be a precursor for thin film formation, and the transfer film may be formed by being converted into a thin film formation material by heat or light before or during transfer. The transfer material may be a material for forming a thin film constituting a device such as an organic TFT, a photoelectric conversion element, or various sensors. That is, the donor substrate of the present invention is not only an organic EL element, but also an organic material or an inorganic material containing a metal, when heated, evaporates, sublimates, or ablate sublimates, or changes in adhesiveness or volume. It is only necessary to transfer from the donor substrate to the transfer destination substrate using the change.

  It is difficult to indicate the thickness of the transfer layer 37 in general according to the functions and the number of transfers. For example, a typical transfer material for a single transfer of a donor material (electron injection material) such as lithium fluoride has a thickness of 1 nm or less. In addition, the film thickness of the transfer material of the electrode material may be 100 nm or more. In the case of the organic EL light emitting layer which is a suitable patterning thin film of the present invention, the thickness of the transfer material for one transfer is preferably 10 to 100 nm, more preferably 20 to 50 nm.

  The transfer layer does not need to be formed of a single material over the entire donor substrate, and a transfer layer having a different color may be arranged for each partition pattern. This is because the color arrangement required by the transfer destination device should be followed.

  The method for forming the transfer layer is not particularly limited, and a dry process such as vacuum deposition or sputtering can also be used. However, as a method that can easily cope with an increase in size, it is preferable to form a transfer layer by applying a solution of at least a transfer material and a solvent in the partition pattern and drying the solvent. Examples of the coating method include inkjet, nozzle coating, electropolymerization and electrodeposition, offset and flexographic printing, lithographic printing, relief printing, gravure, screen printing, and other various printing methods. In particular, in the present invention, it is important to accurately form a fixed amount of transfer material in each partition pattern. From this point of view, it is desirable to apply by inkjet.

  When using a solution consisting of a transfer material and a solvent in a coating method, generally adding a surfactant, a dispersant, etc., adjusts the viscosity, surface tension, dispersibility, etc. of the solution to make an ink. There are many cases. However, in the present invention, if these additives exist as a residue in the transfer material, there is a concern that they will be taken into the transfer film even during transfer and adversely affect device performance. That is, it is preferable that impurities such as a dispersant contained in the transfer film are small. Therefore, it is preferable to prepare the solution so that the purity of the transfer material after drying is 95% or more, and further 98% or more.

  As the solvent, known materials such as water, alcohol, hydrocarbon, aromatic compound, heterocyclic compound, ester, ether, ketone and the like can be used. In the ink jet method suitably used in the present invention, a solvent having a relatively high boiling point of 100 ° C. or higher, more preferably 150 ° C. or higher is used, and the solubility of the organic EL material is excellent. Methylpyrrolidone (NMP), dimethylimidazolidinone (DMI), γ-butyllactone (γBL), ethyl benzoate, tetrahydronaphthalene (THN), cyclohexanone, and the like can be used as suitable solvents.

  When the transfer material satisfies all the solubility, transfer resistance, and device performance after transfer, it is preferable to dissolve the original transfer material in a solvent. When the transfer material is poor in solubility, the solubility can be improved by introducing a soluble group with respect to a solvent such as an alkyl group into the transfer material. When a soluble group is introduced into a prototype of a transfer material that excels in device performance, the performance may deteriorate. In that case, for example, the soluble material can be eliminated by heat at the time of transfer to deposit the original material on the device substrate.

  When transferring a transfer material into which a soluble group has been introduced, the transfer material has a soluble group in the solvent at the time of application to prevent the generation of gas and the incorporation of desorbed material into the transfer film. It is preferable to transfer the transfer material after converting or eliminating the soluble group by. For example, taking a material having a benzene ring as an example, as shown in FIG. 6 (1), a material having an acetyl group as a soluble group can be irradiated with light to be converted into a methyl group. In addition, as shown in FIGS. 6 (2) and (3), an intramolecular cross-linking structure such as an ethylene group or a diketo group is introduced as a soluble group, and the original material is formed by a process of desorbing ethylene or carbon monoxide therefrom. It can also be restored.

  The conversion or elimination of the soluble group may be in a solution state before drying or in a solid state after drying. However, in consideration of process stability, it is preferably performed in a solid state after drying. Since the original molecule of the transfer material is often nonpolar, the molecular weight of the desorbed material is small so that the desorbed material does not remain in the transfer material when the soluble group is removed in the solid state. It is preferably polar (repulsive to the nonpolar prototype molecule). In order to remove oxygen and water adsorbed in the transfer material together with the desorbed material, it is preferable that the desorbed material easily reacts with these molecules. From these viewpoints, it is particularly preferable to convert or eliminate the solubilizing group in the process of eliminating carbon monoxide.

  Examples of the material having a benzene ring include condensed polycyclic compounds in addition to benzene itself. Examples of the condensed polycyclic compound include condensed polycyclic hydrocarbon compounds such as naphthalene, anthracene, naphthacene, pyrene, and perylene, as well as condensed polycyclic hetero compounds. Of course, these may be substituted or unsubstituted. The above conversion or elimination can be performed on one or more benzene rings of these compounds.

  Next, how to use the donor substrate of the present invention will be described. 7 and 8 are a cross-sectional view and a plan view showing an example of the thin film patterning method of the present invention. In the drawings used in this specification, the minimum unit of RGB sub-pixels constituting a large number of pixels in a color display is extracted and described. In order to help understanding, the magnification in the vertical direction (substrate vertical direction) is increased as compared with the horizontal direction (substrate in-plane direction).

  In FIG. 7, the donor substrate 30 includes a support 31, a photothermal conversion layer 33, a partition pattern 34, and a transfer material 37 (coating film of RGB light emitting materials of organic EL) present in the partition pattern. The organic EL element (device substrate) 10 includes a support 11, a TFT (including extraction electrode) 12 formed thereon, a planarization film 13, an insulating layer 14, a first electrode 15, and a hole transport layer 16. In addition, since these are illustrations, the structure of each board | substrate is not limited to these as mentioned later.

  In a state where the partition pattern 34 of the donor substrate 30 and the insulating layer 14 of the device substrate 10 are aligned, the two substrates are arranged to face each other. A laser is incident from the support 31 side of the donor substrate 30 and absorbed by the light-to-heat conversion layer 33, and the transfer materials 37R, 37G, and 37B are simultaneously heated and evaporated by the heat generated there, and they are transported by holes of the device substrate 10. By depositing on the layer 16, the light emitting layers 17R, 17G, and 17B are collectively transferred and formed. Laser irradiation is performed so that the entire region of the partition pattern 34 sandwiched between the transfer materials 37R, 37G, and 37B and a partial region of the partition pattern 34 positioned outside the transfer materials 37R and 37B are heated simultaneously with the transfer material 37. It is possible.

  Furthermore, as one of the preferred embodiments of the present invention, when the thickness of the partition pattern is made thicker than the transfer material, the temperature of the portion of the partition pattern that is thicker than the transfer layer does not increase so much. This is because the partition pattern is heated from the bottom, so that the top has a distance and is not easily warmed. Therefore, the device substrate is not heated to a high temperature through the partition pattern, there is almost no influence of degassing from the partition pattern, and the device performance is not deteriorated.

  In addition, according to the present invention, different transfer materials that are separated by the partition pattern can be simultaneously irradiated with light so as to straddle the partition pattern, so that different transfer materials can be collectively transferred. For example, when RGB light-emitting layers in an organic EL display are patterned according to the present invention, the RGB light-emitting layers can be transferred together as a set, so that it is necessary to sequentially irradiate the RGB light-emitting layers with light. Compared with the conventional method, the patterning time can be shortened.

  Since light is sufficiently absorbed by the light-to-heat conversion layer, RGB light-emitting layers having different light absorption spectra can be heated to the same temperature using the same light source, and the device substrate is heated by the transmitted light. There is no worry. Since the partition pattern exists, adjacent different transfer materials can be mixed and transfer of a portion where the boundary position fluctuates can be eliminated, so that device performance is not impaired even if batch transfer is performed.

  In addition, since the partition pattern can be patterned with high accuracy by a photolithography method or the like, a gap between transfer patterns of different transfer materials can be minimized. This leads to an effect that an organic EL display having a higher aperture ratio and excellent durability can be produced.

  FIG. 8 is a schematic view of the state of laser irradiation in FIG. 7 as viewed from the support 31 side of the donor substrate 30. Since the photothermal conversion layer 33 is formed on the entire surface, the partition pattern 34 and the transfer materials 37R, 37G, and 37B are not actually visible from the support 31 (glass plate) side, but the positional relationship with the laser will be described. Therefore, it is shown by a dotted line. The laser beam has a rectangular shape, is irradiated so as to straddle the transfer materials 37R, 37G, and 37B, and is scanned in a direction perpendicular to the arrangement of the transfer materials 37R, 37G, and 37B. The laser beam only needs to be scanned relatively, and the laser may be moved, the set of the donor substrate 30 and the device substrate 20 may be moved, or both.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated, this invention is not limited by these Examples.

Examples 1 to 3
A donor substrate was prepared as follows. An alkali-free glass substrate was used as a support, and after cleaning / UV ozone treatment, a tatantalum film having a thickness of 0.2 μm, 0.4 μm, or 0.6 μm was formed as a photothermal conversion layer by sputtering. Next, after the photothermal conversion layer has been subjected to UV ozone treatment, a positive polyimide photosensitive coating agent (DL-1000, manufactured by Toray Industries, Inc.) is spin-coated thereon, prebaked and UV exposed, and then a developer. The exposed part was dissolved and removed by (ELM-D manufactured by Toray Industries, Inc.).

The polyimide precursor film thus patterned was baked on a hot plate at 350 ° C. for 10 minutes to form a polyimide-based partition pattern. The partition pattern had a height of 2 μm and a cross section of a forward tapered shape. Openings exposing the photothermal conversion layer having a width of 80 μm and a length of 280 μm were arranged in the partition pattern at a pitch of 100 and 300 μm, respectively. On this substrate, a transfer material having an average thickness of 25 nm made of Alq ₃ was formed in the partition pattern (opening) by spin-coating a chloroform solution containing ₃ wt% of Alq ₃ .

  The case where the thickness of the photothermal conversion layer is 0.2 μm is Example 1, the case of 0.4 μm is Example 2, and the case of 0.6 μm is Example 3.

Examples 4 and 5
Examples 4 and 5 were obtained by forming 0.2 μm of molybdenum or chromium as the photothermal conversion layer. It was produced in the same manner as in Examples 1 to 3 except that the material of the photothermal conversion layer was changed.

Example 6
The photothermal conversion layer was produced in the same manner as in Examples 1 to 3, except that titanium was formed with a thickness of 0.2 μm.

Example 7
The photothermal conversion layer was made of titanium having a thickness of 0.1 μm. Other parts were produced in the same manner as in Examples 1 to 3.

Example 8
A photothermal conversion layer was produced in the same manner as in Examples 1 to 3, except that vanadium was formed at 0.2 μm.

Example 9
The photothermal conversion layer was produced in the same manner as in Examples 1 to 3 except that niobium was formed with a thickness of 0.2 μm.

Example 10
It was produced in the same manner as in Examples 1 to 3 except that chromium 0.1 μm was formed as a photothermal conversion layer on an alkali-free glass substrate and tantalum was formed 0.1 μm on the layer. The calculated values of thermal conductivity and volume specific heat of this photothermal conversion layer were 60.9 W / mK and 3.00 J / cm ³ K, respectively.

Example 11
It was produced in the same manner as in Examples 1 to 3, except that 0.18 μm of chromium was formed as a light-to-heat conversion layer on an alkali-free glass substrate, and tantalum was formed at 0.02 μm on that layer. The calculated values of thermal conductivity and volume specific heat of this photothermal conversion layer were 65.9 W / mK and 3.42 J / cm ³ K, respectively.

Example 12
It was produced in the same manner as in Examples 1 to 3 except that platinum was formed at 0.2 μm as the photothermal conversion layer.

Example 13
The photothermal conversion layer was produced in the same manner as in Examples 1 to 3 except that gold was formed at 0.2 μm.

Example 14
It was produced in the same manner as in Examples 1 to 3, except that 0.1 μm of chromium was formed as a light-to-heat conversion layer on an alkali-free glass substrate and gold was formed at 0.1 μm on the layer. The calculated values of thermal conductivity and volume specific heat of this photothermal conversion layer were 183 W / mK and 3.03 J / cm ³ K, respectively.

Comparative Example 1
The light-to-heat conversion layer was formed with 0.2 μm of chromium only in the portion where the transfer layer was to be formed. The light-to-heat conversion layer does not overlap under the partition pattern. Other parts were produced in the same manner as in Examples 1 to 3.

  The device substrate was produced as follows. A non-alkali glass substrate (manufactured by Geomat Co., Ltd., sputtering film-formed product) on which an ITO transparent conductive film was deposited to 140 nm was cut into 38 × 46 mm, and ITO was etched into a desired shape by a photolithography method. Next, the polyimide precursor film patterned similarly to the donor substrate was baked at 300 ° C. for 10 minutes to form a polyimide-based insulating layer.

The height of this insulating layer was 1.8 μm and the cross section was a forward tapered shape. Openings exposing ITO with a width of 70 μm and a length of 270 μm were arranged at a pitch of 100 and 300 μm inside the pattern of the insulating layer. This substrate was subjected to UV ozone treatment, installed in a vacuum deposition apparatus, and evacuated until the degree of vacuum in the apparatus became 3 × 10 ⁻⁴ Pa or less. By a resistance heating method, 20 nm of copper phthalocyanine (CuPc) and 40 nm of NPD were stacked as a hole transport layer by vapor deposition over the entire light emitting region.

The transfer layer was transferred to the device substrate using the donor substrate of Examples and Comparative Examples. Specifically, the positions of the partition pattern of the donor substrate and the insulating layer of the device substrate were aligned and held in a vacuum of 3 × 10 ⁻⁴ Pa or less, and then taken out into the atmosphere. The transfer space partitioned by the insulating layer and the partition pattern was kept in a vacuum. In this state, a laser (light source: semiconductor laser diode) having a wavelength of about 800 nm is irradiated from the glass substrate side of the donor substrate so that a part of the transfer material and a part of the partition pattern are heated at the same time. ₃ was transferred onto the hole transport layer which is the underlying layer of the device substrate. The laser intensity is adjusted to 10-80 W / mm ² according to the film thickness of the light-to-heat conversion layer, the scan speed is 0.1, and the laser is overlapped so that it is transferred to the entire light emitting area. Carried out.

The device substrate after Alq ₃ transfer, and reinstalled in a vacuum evaporation apparatus was evacuated to a vacuum degree in the apparatus is equal to or less than 3 × 10 -4 ^Pa. E-1 shown below as an electron transport layer was deposited on the entire surface of the light emitting region by resistance heating. Next, lithium fluoride was deposited at 0.5 nm as a donor material (electron injection layer), and aluminum was deposited at 100 nm as a second electrode, thereby producing an organic EL device having a 5 mm square light emitting region.

  Thereafter, the inside of the partition pattern of the donor substrate was visually observed with a microscope. As a result, when there is no transfer residue of the transfer layer in the partition pattern, it is judged as “good”, and when a little transfer material remains near the boundary between the partition pattern and the photothermal conversion layer, it is judged as “good”. A case where the transfer material clearly remained in the portion was judged as “bad”.

  The results are shown in Table 2. Table 1 shows the thermal conductivity, volume specific heat, density, and specific heat of chromium, molybdenum, tantalum, titanium, niobium, vanadium, platinum, and gold used in the examples. Among the eight metals, titanium has the lowest thermal conductivity of 17.1 W / mK. In Example 6 in which a light-to-heat conversion layer having a thickness of 0.2 μm was formed using this titanium, a slight residual transfer material was observed at the boundary between the light-to-heat conversion layer and the partition pattern. In all other Examples 1 to 5, there was no untransferred residue, and it was judged as “good”.

  Further, in Example 7 in which titanium was further thinned (0.1 μm), a slight transfer residue of the transfer material was recognized at the boundary of the partition pattern, and it was judged as “good” to “bad”. In addition, on the EL element side to which the transfer material was transferred, there was a thin region of the light emitting layer at this time, and the blue light emission from the hole transport layer was slightly mixed, and it was judged as “slightly abnormal”. This is presumably because if the light-to-heat conversion layer is thin, the partition pattern is deprived of heat and easily cooled locally, resulting in a large temperature unevenness.

  On the other hand, in Comparative Example 1 configured such that the lower side of the partition pattern was in direct contact with the support plate, transfer residue of the transfer material was recognized at the boundary between the light-to-heat conversion layer and the partition pattern, and was judged to be “bad”. In the light-to-heat conversion layer, the irradiated laser is converted into heat, but due to the small heat capacity of the light-to-heat conversion layer, when thermal diffusion occurs in the partition pattern, the temperature drop of the light-to-heat conversion layer is large and the transfer is sufficiently It is thought that it was not done.

  In Comparative Example 1, a thin abnormal region of the light emitting layer was observed even in the produced organic EL, and blue light emission from the hole transport layer was mixed. Although the phenomenon was similar to that in Example 7, since the mixed emission color was clear from Example 7, the EL element side was determined to be “abnormal”.

The organic EL element in which no abnormality was observed on the EL element side was further caused to emit light under a current condition of 10 mA / cm ² , the front luminance was measured with a spectral radiance meter, and the luminous efficiency (cd / A) was calculated. Based on an organic EL device in which all layers including a light emitting layer (Alq ₃ of 25 nm) were similarly prepared by vapor deposition, “normal” when the rate of decrease in luminous efficiency is less than 10%, and 10% or more and 40% Table 2 shows the results of “a little decrease” if the decrease was less than “lower” and “large decrease” if the decrease was 40% or more. When the material on the surface of the light-to-heat conversion layer in contact with the transfer material is a Group 5 metal or a noble metal, a tendency for performance degradation to be suppressed was observed.

10 Organic EL elements (device substrates)
11 Support 12 TFT (including extraction electrode)
DESCRIPTION OF SYMBOLS 13 Flattening film 14 Insulating layer 15 1st electrode 16 Hole transport layer 17 Light emitting layer 18 Electron transport layer 19 Second electrode 20 Device substrate 21 Support body 27 Transfer film 30 Donor substrate 31 Support body 33 Photothermal conversion layer 34 Partition pattern 37 Transfer material 39 Transfer auxiliary layer 60 Partition pattern height 61 Partition pattern upper surface 64 Liquid repellent layer 66 Partition pattern upper surface width 67 Section width

Claims (9)

A donor substrate for transfer comprising a substrate, a photothermal conversion layer formed on the substrate, a partition pattern formed at least partially on the top surface of the photothermal conversion layer, and a transfer layer formed in the partition pattern. The transfer donor substrate according to claim 1, wherein the transfer layer is made of a transfer material different in at least one partition pattern and in another partition pattern. The transfer donor substrate according to claim 1, wherein the photothermal conversion layer includes a metal film having a thickness of 0.2 μm or more. The transfer donor substrate according to any one of claims 1 to 3, wherein the photothermal conversion layer has a thermal conductivity of 50 W / mK or more. Transfer donor substrate according to any one of claims 1 to 4, characterized in that the volume specific heat of the light-to-heat conversion layer is 2J / cm 3 ^K or more. The photothermal conversion layer is a single metal layer, and the metal is a metal selected from the group consisting of vanadium, niobium, tantalum, gold, silver, platinum, palladium, rhodium, iridium, ruthenium and osmium. 5. A donor substrate for transfer according to any one of claims 5. The photothermal conversion layer is composed of a plurality of layers, and the layer in contact with the transfer layer among the plurality of layers is selected from the group consisting of vanadium, niobium, tantalum, gold, silver, platinum, palladium, rhodium, iridium, ruthenium and osmium. The donor substrate for transfer according to any one of claims 1 to 5, which is a metal. The transfer donor substrate according to any one of claims 1 to 7, wherein the transfer layer is made of an organic EL element constituent material. A method for manufacturing a device, comprising: a step of causing the transfer donor substrate according to any one of claims 1 to 8 to face a device substrate; and a step of irradiating the photothermal conversion layer with light.

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