JP2010267410A - Method for manufacturing donor substrate and display element used in laser transfer method - Google Patents

Abstract

The accuracy of alignment of a transfer substrate, a donor substrate and a laser is improved by a simple mechanism.
A donor substrate on which a transfer layer is formed and a substrate to be transferred are opposed to each other, and transfer is performed a plurality of times from one donor substrate to a plurality of substrates to be transferred. The donor substrate 01 is provided with a plurality of irregularities 03 at a constant pitch that matches the pixel pitch. Transfer is performed by applying energy while following the laser 06 to a desired position (unevenness 03) of the donor substrate 01.
[Selection] Figure 1

Description

  The present invention relates to a donor substrate for transferring a transfer layer formed on a donor substrate to the substrate by laser irradiation, and a method for manufacturing a display element by a transfer method using a laser.

  An organic EL element using organic electroluminescence (hereinafter referred to as EL) is attracting attention as a light emitting element capable of emitting light with high luminance by low voltage driving.

  In order to achieve full color in the manufacturing method of the organic EL element, it is necessary to selectively form each luminescent organic material of R (red), G (green), and B (blue) on the electrode as a fine pattern. is there. In manufacturing such a light emitting device, a method of transferring a transfer layer to a substrate using a laser has been proposed.

  However, this method has a problem that the transfer layer remains on the donor substrate after the transfer, and the material use efficiency is poor. Therefore, as a pattern forming method for the organic EL element, in order to effectively use the transfer layer of the donor substrate, a method of providing an alignment mark and transferring a plurality of times has been proposed. In this method, a plurality of marks for aligning the donor substrate with the transfer substrate are provided corresponding to different alignment relationships (see Patent Document 1).

JP 2006-309994 A

  However, the conventional method described above has the following problems.

  That is, in the conventional transfer method, for example, three alignment marks are formed, and these alignment marks are detected to align the donor substrate and the transfer substrate. In this transfer method, when performing alignment of the transfer substrate, donor substrate, and laser, the width of the transfer region is 15 μm, the laser width is 25 μm, the pitch is 30 μm, and the position control accuracy of each component is ± 5 μm. Assume that the transfer is performed three times from one donor substrate.

  FIG. 7 is a schematic cross-sectional view showing a method for manufacturing an organic EL element according to a conventional example. For simplification, the donor substrate 01 shows only the support body 02 and the transfer layer 05. In addition, the transfer layer 05 includes a first transfer area 31, a second transfer area 32, and a third transfer area 33.

  As shown in FIG. 7A, assume that the donor substrate 01 and the laser are shifted by +5 μm and −5 μm, respectively, with respect to the first transfer substrate 37 in the first transfer. In this case, in the first transfer, not only the first transfer area 31 but also a part of the second transfer area 32 is transferred. That is, a part 34 of the first transfer region and a part 35 of the second transfer region are transferred to the first transfer substrate 37.

  As shown in FIG. 7B, it is assumed that the donor substrate 01 and the laser 06 are shifted by +5 μm from the second transfer substrate 38 in the second transfer. In this case, since a part of the second transfer region 32 to be transferred is transferred by the first transfer, it does not exist as a trace 36 of a part of the second transfer region. In the transfer, there is a problem that only a part of the transfer film is transferred to the lower electrode 12. In FIG. 7, reference numeral 06 denotes a laser, reference numeral 12 denotes a lower electrode, and reference numeral 13 denotes an insulating film.

  If an apparatus having a highly accurate stage and alignment mechanism is used, alignment can be performed at ± 5 μm or less. However, an expensive manufacturing apparatus is used, which causes an increase in cost.

  Accordingly, the present invention provides a donor substrate and a display element that can transfer a transfer layer of a donor substrate a plurality of times without using an expensive high-precision alignment control mechanism, and can use the transfer layer without waste. It aims at providing the manufacturing method of.

  In order to solve the above-described problems, the donor substrate and the display element manufacturing method of the present invention have the following features. That is, according to the method for manufacturing a donor substrate and a display element of the present invention, a donor substrate on which a transfer layer is formed and a substrate to be transferred are opposed to each other, and transfer is performed multiple times from one donor substrate to a plurality of substrates to be transferred. It is used when. The donor substrate of the present invention is characterized in that a plurality of irregularities are provided at a constant pitch in accordance with the pixel pitch. The display element manufacturing method of the present invention is characterized in that energy is applied to a desired position of the donor substrate, specifically, the laser is caused to follow the unevenness formed on the donor substrate and transferred. is there.

  According to the donor substrate and display element manufacturing method of the present invention, the transfer layer of the donor substrate can be transferred a plurality of times without using an expensive high-precision alignment control mechanism, so that the transfer layer can be used without waste. It becomes possible. As a result, the material use efficiency can be improved, and donor creation costs and regeneration costs can be reduced.

It is a schematic diagram which shows the tracking to the donor substrate which concerns on embodiment of this invention. It is typical sectional drawing which shows the manufacturing method of the donor substrate which concerns on embodiment of this invention. It is typical sectional drawing which shows the example of the donor substrate which concerns on embodiment of this invention. It is a schematic plan view which shows the manufacturing method of the organic EL element which concerns on embodiment of this invention. It is a typical top view of a light receiving element concerning an embodiment of the present invention. It is a schematic plan view which shows the tracking to the donor substrate which concerns on embodiment of this invention. It is typical sectional drawing which shows the manufacturing method of the organic EL element which concerns on a prior art example.

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

  In the method for manufacturing a donor substrate and a display element according to an embodiment of the present invention, a donor substrate on which a transfer layer is formed and a substrate to be transferred are opposed to each other, and transfer is performed multiple times from one donor substrate to a plurality of substrates to be transferred. It is used when performing. The donor substrate is provided with a plurality of irregularities at a constant pitch that matches the pixel pitch. Then, transfer is performed by applying energy while causing the laser to follow a desired position of the donor substrate, specifically, the unevenness formed on the donor substrate. In this case, it is preferable to use a plurality of lasers to cause the lasers to follow desired positions of the donor substrate (unevenness formed on the donor substrate). The laser is preferably composed of a transfer laser and a follow-up laser. In the method for manufacturing a donor substrate and a display element having such a configuration, a donor substrate for transferring a transfer layer can be used efficiently.

  In the following description, the pixel pattern is composed of three types of regions of R (red), G (green), and B (blue). However, the present invention is not limited to this, and R (red), G (green), B (blue), W (white), and the like may be used.

  FIG. 1 is a schematic diagram illustrating tracking of a donor substrate according to an embodiment of the present invention. The support body 02 of the donor substrate 01 has an unevenness 03 corresponding to the transfer region. By irradiating the laser 06 through the objective lens 09, the reflected light (0th-order diffracted light 07) and the first-order diffracted light 08 are 2D-Photo Detector10. (Hereinafter referred to as 2D-PD). Then, a tracking error signal (hereinafter referred to as a TE signal) is generated and fed back to the actuator mechanism of the objective lens 09, whereby irradiation is performed while the laser 06 follows the unevenness 03 to perform transfer.

  The present embodiment is characterized in that the support 02 of the donor substrate 01 has irregularities 03 and the laser 06 follows the irregularities 03. The unevenness 03 may be a line-shaped groove corresponding to the transfer region, a line segment, or a pit. In the case of the pit-shaped concavo-convex 03, it can be detected by the 2D-PD 10 in the same manner by looking at the balance of the drop in the amount of light due to the left and right pits between pixels.

  Further, tracking may be performed using a transfer laser, or tracking and transfer irradiation may be performed by providing a tracking laser separately from the transfer laser. In this case, a wavelength or power different from that of the transfer laser can be selected as the tracking laser.

<Donor substrate formation process>
Next, a method for manufacturing a display element according to this embodiment will be described.

  FIG. 2 is a schematic cross-sectional view showing a method for manufacturing a donor substrate according to an embodiment of the present invention, and FIG. 3 is a schematic cross-sectional view showing an example of a donor substrate according to an embodiment of the present invention.

  First, as shown in FIG. 2A, a donor substrate support 02 is prepared. As a material of the support body 02, a material having transparency to a laser such as glass or a film is desirable.

  Subsequently, as shown in FIG. 2B, unevenness 03 is formed. A plurality of irregularities 03 are provided at a constant pitch that matches the pitch of the pixels. The depth of the irregularities 03 can be optimally selected according to the wavelength of the laser that generates the tracking error signal. As for the processing method of the unevenness 03, for example, a part of the support body 02 may be removed by using photolithography, nanoimprinting, laser processing, or the like, or a convex portion may be formed on the support body 02.

  Subsequently, as illustrated in FIG. 2C, the light absorption layer 04 is formed on the support body 02 provided with the unevenness 03. The light absorption layer 04 is a material that absorbs laser and is appropriately selected according to the transfer method. At this time, the reflected light is selected so as to return to the laser that generates the tracking error signal. Further, the light absorption layer 04 may be divided into a plurality of layers by adding a layer for controlling the adhesion strength and peelability of the transfer layer 05, heat conduction and reflectance, etc., if necessary.

  The configuration of the donor substrate is appropriately selected according to various transfer methods. Further, the unevenness 03 may be the front surface, the back surface, or the inside of the support body 02, and may be formed on the light absorption layer 04 or other functional layers.

  Subsequently, as illustrated in FIG. 2D, a transfer layer 05 including at least a light emitting layer is formed on the light absorbing layer 04.

  Further, as shown in FIGS. 3A and 3B, the area to be transferred may be convex or concave.

<Lower electrode and auxiliary electrode formation process>
Next, the formation of the lower electrode will be described. In the case of an active matrix display element, a thin film transistor is already formed in each pixel on the substrate. FIG. 4 is a schematic plan view showing a method for manufacturing an organic EL element according to an embodiment of the present invention.

  First, as shown in FIG. 4A, the lower electrode 12 is patterned on the substrate 11. The lower electrode 12 is used as an anode electrode or a cathode electrode. In the case of the top emission type, the lower electrode 12 is formed of a material having a high reflectance with respect to visible light, and in the case of the bottom emission type, visible light is used. It is formed transparent to.

  When using the top emission type and the lower electrode 12 as an anode electrode, the following materials can be used. That is, as an electrode of an organic EL element such as a conductive material having high reflectivity with respect to visible light, such as Ag, Al, Au, or an alloy thereof, ITO (Indium Tin Oxide), IZO (Indium Zinc Oxide), or ZnO. It is a known material. Further, in the case of using the bottom emission 12 as a cathode electrode in the top emission type, a conductive material having a small work function such as Al, In, Mg, or Ag alloy and a material having high reflectivity with respect to visible light should be used. it can.

  When the bottom emission type is used as the anode electrode in the bottom emission type, a conductive material having a high transmittance with respect to visible light, such as ITO or IZO, can be used. Further, when the bottom emission type is used as the cathode electrode in the bottom emission type, a conductive material having a small work function and high transmittance with respect to visible light can be used.

  Here, an auxiliary electrode or the like may be formed. As the auxiliary electrode, a low-resistance conductive material such as Al, Cr, or an alloy thereof can be used as a single layer or a stacked layer.

<Insulating film formation process>
Next, an insulating film 13 is formed so as to cover the edge of the lower electrode 12. For example, after forming the insulating film 13, the lower electrode 12 is exposed by photolithography to form a pixel region. You may form using the apply | coating method. For the insulating film 13, for example, an organic insulating material such as polyimide or photoresist, or an inorganic insulating material such as silicon oxide can be used.

<Organic layer A formation process>
Thereafter, as shown in FIG. 4B, an organic layer A14 is sequentially formed on the lower electrode 12 of each pixel as necessary. The organic layer A14 is formed so as to completely cover the exposed surface of the lower electrode 12. Although not shown, the organic layer A14 may have a layer having functions such as a hole transport layer, an electron transport layer, and an electron injection layer as necessary. A known material can be used for each layer of the organic layer A14.

  Of course, the present invention is also applied to an element in which the common layer is formed on the entire surface without a mask and the light emitting layer is separately coated with R (red), G (green), B (blue), W (white), and the like. be able to. Furthermore, the present invention can be applied to a display element in which a white element having a plurality of emission peaks is formed, and also to a tandem organic EL element in which a plurality of organic layer units having a light emitting layer are stacked.

  In the example shown in FIG. 4, for the sake of simplicity, a case where a solid organic film is formed is shown.

<Transfer process>
Next, as shown in FIG. 4C, the transfer is performed by irradiating the laser 06 from the back surface of the donor substrate 01. At this time, irradiation is performed while the laser 06 follows the unevenness (not shown) formed on the donor substrate 01. Depending on the various transfer methods, the laser type for transfer can be any laser such as semiconductor laser, YAG laser, YVO4 laser, various gas lasers such as excimer, mask, condensing state, homogenization, scanning method, Power etc. are selected. For the tracking, a known technique such as a push-pull method described later can be used. Further, the transfer laser irradiation may be continuous or partial along the unevenness. In FIG. 4C, reference numeral 04 denotes a light absorption layer.

<Organic layer B forming step>
Thereafter, as shown in FIG. 4D, an organic layer B15 is sequentially formed on the transfer layer 05 of each pixel as necessary.

  Although not shown, the organic layer B15 may have a layer having functions such as a hole transport layer, an electron transport layer, and an electron injection layer as necessary. A known material can be used for each layer of the organic layer B15.

<Upper electrode formation process>
Further, the upper electrode 16 is formed on the organic layer B15. As the upper electrode 16, a known material is used as an electrode material of an organic EL element such as ITO or IZO. Since the upper electrode 16 is used as an anode electrode or a cathode electrode, the top electrode 16 is formed to be transparent or translucent to visible light in the case of the top emission type, and to visible light in the case of the bottom emission type. And made of highly reflective material.

  Here, since the display element is a top emission type and the lower electrode 12 is used as an anode electrode, the upper electrode 16 is used as a cathode electrode. In this case, the upper electrode 16 preferably has a small work function and is transparent to visible light so that electrons can be efficiently injected into the organic layer B15. As the material, a suitable material such as an Mg—Ag alloy is used.

  Further, when the display element is a bottom emission type and the upper electrode 16 is used as a cathode electrode, the display element is made of a conductive material having a small work function and a high reflectance with respect to visible light.

  Furthermore, when the display element is a bottom emission type and the upper electrode 16 is used as an anode electrode, a conductive material having a high reflectance with respect to visible light is used.

  The film thickness is preferably 5 nm or more because if it is too thin, the electron or hole injectability deteriorates. Moreover, since absorption of emitted light will increase when too thick, it is desirable that it is 200 nm or less. Furthermore, it is even more desirable to be thinner than 100 nm.

<Protective film formation process>
Finally, although not shown, a protective film is formed on the upper electrode 16. At this time, the protective film is formed by a method in which the energy of the film-forming particles is small so as not to affect the base. By forming the protective film without exposing it to the atmosphere, it prevents deterioration due to moisture and oxygen in the atmosphere. This protective film may be formed of a moisture-proof material with a sufficient thickness for the purpose of preventing contact of moisture and oxygen with the organic layer A14, the organic layer B15, and the transfer layer 05.

  In the top emission type, this protective film is also made of a material having a high transmittance with respect to visible light. For example, amorphous silicon, silicon carbide, silicon nitride, or the like can be preferably used. In this case, it is desirable to form the film so that the film forming temperature is close to room temperature and the film stress is small.

<Follow-up>
Next, the following in the transfer process will be described.

  As shown in FIG. 1, in a state where the tracking laser 06 is focused on the unevenness 03, the light reflected and diffracted by the unevenness 03 is received on two 2D-PDs 10 arranged symmetrically with respect to the center. An error signal can be detected by taking out as an output difference in the unit.

  When the spot of the laser 06 and the center of the concavo-convex 03 coincide with each other, a symmetrical diffraction diffraction distribution is obtained, and in other cases, the light intensity is shifted on the left and right.

  When the pitch of the projections and depressions 03 becomes the size of the light spot, the projections and depressions 03 look like diffraction gratings, so that the light phases overlap in the direction satisfying Psinθ = Nλ (N: integer), and the light intensity increases. .

  That is, in the region where the 0th-order and 1st-order diffracted light overlap, the intensity distribution of the laser spot changes due to the interference effect due to the track shift, and the TE signal can be detected by placing the 2D-PD 10 here. The laser intensity pattern on the photodiode is determined by the NA of the objective lens 09, the track pitch, and the laser wavelength.

  When λ / 8n (n is the refractive index of the substrate), the TE signal is the largest.

  By feeding back this TE signal to the actuator mechanism of the objective lens 09, it is possible to follow the unevenness 03. In this way, the alignment between the donor substrate 01 and the laser 06 can be aligned with an accuracy of 1 μm or less. Therefore, if the donor substrate 01 is aligned with an accuracy of ± 5 μm with respect to the transfer substrate, one donor substrate 01 is obtained. Can be transferred three times.

  In the example described above, the method of performing tracking using a laser for transfer is shown, but the present invention is not limited to this, and a tracking laser may be provided in addition to the transfer laser, and a plurality of lasers are used. May be. For example, two lasers may be arranged and a differential push-pull method: DPP (Differential Push Pull) method may be used.

  FIG. 5 is a schematic plan view of the light receiving element according to the embodiment of the present invention, and FIG. 6 is a schematic plan view showing the follow-up to the donor substrate according to the embodiment of the present invention.

  In the case of the DPP method, as shown in FIG. 5, the light receiving element has a quadrant shape at the center and a bipartite shape on both sides. In FIG. 5, reference numeral 21 denotes main beads, reference numeral 22 denotes a sub beam A, and reference numeral 23 denotes a sub beam B.

  The donor substrate shown in FIG. 6 has, for example, a cross-sectional shape as shown in FIG. Then, the main beam 21 is arranged in the center of the region to be transferred, and the sub beam A22 and the sub beam B23 are irradiated at a position shifted by, for example, 1/2 pitch in the direction perpendicular to the irradiation scanning direction indicated by the arrow in FIG. Here, the transfer laser is the main beam.

  When the push-pull signal of the main beam 21 obtained from the central four-dividing element is MPP and the push-pull signals of the sub beams A22 and B23 obtained from the left and right two-dividing elements are SPP, the TE signal is TE = MPP-SPP. Is generated by However, MPP = (A + D) − (B + C), SPP = {(E−F) + (G−H)} / 2. The focus signal is generated by the astigmatism method (A + C) − (B + D).

  According to the DPP method, since the push-pull signal of the main beam and the push-pull signal of the sub beam have the same offset amount due to the lateral movement and inclination of the objective lens, there is an advantage that the offset due to these can be canceled.

  Next, a specific embodiment will be described with reference to FIG. As will be described from the formation of the lower electrode 2, it is assumed that a thin film transistor is already formed in each pixel on the substrate 11 in an active matrix display element. For simplicity, the element is described in a single color.

  First, the lower electrode 12 is patterned on the substrate 11.

  The lower electrode 12 was formed by sputtering a laminated film of 100 nm thick Al and 50 nm thick ITO. The lower electrode 12 was formed on the entire surface of the multilayer body on the substrate 11 and then formed into an organic EL element pattern corresponding to the pixel circuit by photolithography.

  Subsequently, an insulating film 13 was formed with polyimide so as to cover the lower electrode 12, and the insulating film 13 was removed by photolithography to expose the lower electrode 12 to form a pixel region.

  Subsequently, an organic layer A14 was formed on the lower electrode 12 by a vapor deposition method. A hole transport layer made of a known organic material was formed on the organic layer A14 using a resistance heating vapor deposition method.

  The support body 02 of the donor substrate 01 was made of glass, and as shown in FIG. 2, the unevenness 03 was provided by photolithography so as to correspond to the pixel pitch. The pitch of the irregularities 03 was 30 μm, and the groove width was 3 μm.

  Further, as a light absorber, tungsten was formed with a thickness of 300 nm using a sputtering method. Further, a light emitting layer as a transfer layer was formed using a resistance heating vapor deposition method. The film thickness was 4.0 nm.

  Subsequently, the substrate 11 and the donor substrate were aligned to face each other, and a semiconductor laser having a wavelength of 810 nm was irradiated while following the unevenness, whereby the transfer layer made of the light emitting layer was transferred from the donor substrate 01 to the substrate 11.

  Further, an electron transport layer and an electron injection layer were stacked and formed as an organic layer B15 on the transferred transfer layer by using a resistance heating vapor deposition method.

  Subsequently, as the upper electrode 16, a 40 nm-thick Mg—Ag alloy was formed by resistance heating vapor deposition.

Finally, an inorganic protective film made of silicon nitride was formed by a plasma CVD method using SiH ₄ gas, N ₂ gas, and H ₂ gas. The protective film was formed to have a thickness of 1 μm so as to cover the entire substrate surface on which the organic EL element was formed.

  Through the above steps, an organic EL element was obtained.

  Further, in the same manner, using the same donor, the laser, the donor, and the substrate were aligned, and the second and third transfer were performed from one donor substrate, and an organic EL device was obtained in the same manner.

  In the organic EL element manufactured by such a manufacturing method, the transfer layer of the donor substrate can be transferred a plurality of times without using an expensive high-precision alignment control mechanism. For this reason, since the transfer layer can be used without waste, the material use efficiency can be improved, and the donor production cost and the regeneration cost can be reduced. Such an effect can be achieved more reliably by using a donor substrate provided with a plurality of irregularities at a constant pitch in accordance with the pixel pitch. Moreover, such an effect can be achieved more reliably by following the donor substrate using a plurality of lasers. Further, by dividing the laser into a transfer laser and a follow-up laser, such an effect can be achieved more reliably.

01: Donor substrate, 02: Support, 03: Concavity and convexity, 04: Light absorption layer, 05: Transfer layer, 06: Laser, 07: 0th order diffracted light, 08: 1st order diffracted light, 09: Objective lens, 10: 2D- PD: 11: substrate, 12: lower electrode, 13: insulating film, 14: organic layer A, 15: organic layer B, 16: upper electrode, 21: main beam, 22: sub beam A, 23: sub beam B, 31: First transfer region, 32: Second transfer region, 33: Third transfer region, 34: Part of first transfer region, 35: Part of second transfer region, 36: Second transfer Trace of a part of the region, 37: first substrate to be transferred in the first transfer, 38: second substrate to be transferred in the second transfer

Claims (4)

A donor substrate used in manufacturing a display element by transferring a donor substrate on which a transfer layer is formed and a substrate to be transferred to each other and transferring a plurality of times from one donor substrate to a plurality of substrates to be transferred. And
A donor substrate used in a transfer system using a laser, wherein a plurality of irregularities are provided at a constant pitch in accordance with a pixel pitch. In a manufacturing method for manufacturing a display element by facing a donor substrate on which a transfer layer is formed and a substrate to be transferred, and transferring a plurality of times from one donor substrate to a plurality of transfer substrates,
A method of manufacturing a display element, wherein energy is applied to a concavo-convex formed on the donor substrate while transferring the energy to follow the laser.   The method for manufacturing a display element according to claim 2, wherein a plurality of lasers are used to cause the lasers to follow the irregularities formed on the donor substrate.   The method of manufacturing a display element according to claim 3, wherein the laser includes a transfer laser and a follow-up laser.

Images