JP2009134067A - Method for manufacturing electrooptical device, and electrooptical device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing an electrooptical device, which can constitute an optical resonator structure in each pixel with a minimized number of steps and good yield, and to provide an electrooptical device. <P>SOLUTION: In the electrooptical device 100, each of a first pixel 11R for emitting red light, a second pixel 11G for emitting green light, and a third pixel 11B for emitting blue light is provided with an optical resonator structure. In constitution of such an optical resonator structure, a resist mask is formed on a translucent film for forming a translucent insulating film 73 so that the film thickness satisfies the relation: the first pixel 11R>the second pixel 11G>the third pixel 11B, the resist mask is thereafter removed from the surface side, and a part exposed from the resist mask in the translucent film is also removed from the surface side to leave the translucent film as an optical distance adjustment layer differed in film thickness in each pixel 11. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for manufacturing an electro-optical device such as an organic electroluminescence (hereinafter referred to as organic EL (Electro Luminescent)) device, and an electro-optical device.

  An organic EL device, which is a typical electro-optical device, uses an organic EL element in which a light emitting layer is interposed between a first electrode layer and a second electrode layer, and light emitted from the organic EL element. Has a broad spectrum peak width and low intensity. Therefore, when the organic EL device is used as a color display device, there is a problem that it is difficult to ensure sufficient color reproducibility.

Therefore, a first pixel for emitting red light (first wavelength light), a second pixel for emitting green light (second wavelength light), and blue light (third wavelength light) are emitted. In each of the third pixels, a light reflecting layer is formed on the opposite side of the first electrode layer from the second electrode layer, and an optical distance between the light reflecting layer and the second electrode layer is set as follows: Relationship The optical resonator structure is configured by changing the type and number of layers interposed between the light reflection layer and the second electrode layer for each pixel so as to satisfy the first pixel> second pixel> third pixel. Has been proposed. With this configuration, the light emitted from the light emitting layer reciprocates between the light reflecting layer and the second electrode layer facing each other with the light emitting layer interposed therebetween, and the light reflecting layer and the second electrode layer Since the light having the resonance wavelength corresponding to the optical distance is selectively amplified, light having a narrow spectrum peak width and high intensity can be emitted from each pixel (for example, see Patent Documents 1 and 2). ).
International Publication No. 01/039554 Pamphlet JP 2007-26972 A

  However, when the optical resonator structure is configured by changing the type and number of layers interposed between the light reflecting layer and the second electrode layer for each pixel as in the configuration disclosed in the above-mentioned patent document, in the manufacturing process, As a result, the number of patterning increases, and the productivity is lowered. For example, as shown in FIG. 11, a first pixel 11R for emitting red light (first wavelength light), a second pixel 11G for emitting green light (second wavelength light), and blue light. In each of the third pixels 11B for emitting (light of the third wavelength), a light reflection layer 4a, a translucent insulating film 73, a first electrode made of ITO (Indium Tin Oxide) or IZO (Indium Zinc Oxide). In the case where the layer 9a (pixel electrode), the hole injection layer 81, the light emitting layer 82, and the second electrode layer 85 are sequentially stacked, an optical resonator structure is provided between the light reflecting layer 4a and the second electrode layer 85. In the first pixel 11R, the first electrode layer 9a is formed by three layers of ITO film, in the second pixel 11G, the first electrode layer 9a is formed by two layers of ITO film, and in the third pixel 11B, The first electrode layer 9a was formed by one layer of ITO film. If, the step of forming the ITO film, and it is necessary to perform the patterning process using a photolithography technique three times, the productivity is low. Moreover, when an ITO film is laminated, the interlayer may act on the reflective interface. Further, when the ITO film is laminated, it is necessary to provide an alignment margin so that a processing error can be absorbed. As a result, the shape accuracy of the first electrode layer 9a is lowered. Furthermore, if the patterning process is performed three times, there is a risk that a patterning defect may occur starting from a pinhole generated in the light-transmitting insulating film 73 or a foreign matter adhering to the light-transmitting insulating film 73.

  In view of the above problems, an object of the present invention is to provide an electro-optical device manufacturing method and an electro-optical device capable of forming an appropriate optical resonator structure for each pixel with a small number of steps and high yield. There is.

In order to solve the above problem, in the present invention, at least a first pixel for emitting light of a first wavelength, a second pixel for emitting light of a second wavelength shorter than the first wavelength, And a third pixel for emitting light having a third wavelength shorter than the first wavelength and the second wavelength, and each of the first pixel, the second pixel, and the third pixel has a film thickness. In the method of manufacturing an electro-optical device including an optical resonator structure including an optical distance adjustment layer satisfying the following relationship: the first pixel> the second pixel> the third pixel,
In forming the optical distance adjustment layer,
A translucent film forming step of forming a translucent film for configuring the optical distance adjustment layer for the first pixel, the second pixel, and the third pixel;
A mask forming step of forming a mask on the upper layer of the translucent film so that the film thickness satisfies the following relationship: the first pixel> the second pixel> the third pixel;
The mask is removed from the surface side, and a portion of the light transmissive film exposed from the mask is removed from the surface side so that the light transmissive film is different between the first pixel, the second pixel, and the third pixel. A removal step to leave as the optical distance adjustment layer of the film thickness;
It is characterized by performing.

  In the present invention, “electro-optical device” means a device that converts electricity into light, such as an organic EL device, a plasma display device, a liquid crystal device, or a sensor, or a device that converts light into electricity.

  In the present invention, a translucent film forming step for forming a translucent film for constituting the optical distance adjusting layer, a mask forming step for forming a mask having a different thickness for each pixel, and the mask and the translucent film on the surface The optical distance adjustment layer having a different thickness can be formed in each pixel simply by performing the removal step of removing from the side, and the optical resonator structure can be formed in each pixel with a small number of steps. Therefore, the productivity of the electro-optical device can be improved. In addition, since the optical distance adjustment layer can be formed of a single light-transmitting film, unnecessary reflection is caused in the optical distance adjustment layer, unlike the case where the optical distance adjustment layer is formed of a plurality of layers. It does not occur. Further, when the optical distance adjustment layer is formed, it is not necessary to repeat the film forming process and the patterning process, so that it is possible to avoid the occurrence of problems that occur when performing a plurality of patterning processes, and to improve the yield. be able to.

  In the present invention, in the mask formation step, after forming a resist layer on the upper layer of the light-transmitting film, gradation exposure is performed to expose the resist layer with different exposure amounts for each region, and then development is performed. It is preferable to form a resist mask as the mask. With this configuration, it is possible to form masks having different thicknesses for each pixel in a single exposure process.

In the present invention, in the translucent film forming step, the translucent film is also formed in a non-formation region of the optical distance adjusting layer, and in the mask forming step, the film thickness is as follows on the translucent film. Relationship It is preferable that the third pixel> the mask so as to satisfy the non-formation region, and the light-transmitting film on the non-formation region is completely removed in the removal step. According to this configuration, when the optical distance adjustment layer having a different thickness for each pixel is formed, a region without the optical distance adjustment layer (non-formation area of the optical distance adjustment layer) can be formed at the same time.

  In the present invention, in the removing step, the mask is removed from the surface side, and the thinnest portion of the mask is removed to expose a part of the surface of the translucent film; It is possible to adopt a configuration in which the etching process for removing the portion of the optical film exposed from the mask from the surface side is alternately performed at least twice.

  In the present invention, the removing step may employ a configuration in which dry etching is performed under conditions that allow both the mask and the light-transmitting film to be etched.

  In the present invention, each of the first pixel, the second pixel, and the third pixel includes at least a light reflection layer, a first electrode layer, a light emitting layer of an organic EL element, and a second electrode layer on the substrate. The first pixel, the second pixel, and the third pixel are sequentially stacked, and each has the optical resonator structure between the light reflecting layer and the second electrode layer. be able to.

  In the present invention, the optical distance adjustment layer may be formed of a translucent insulating film formed as the translucent film after forming the light reflecting layer and before forming the first electrode layer. Can do.

  In the present invention, the optical distance adjusting layer may be the first electrode layer made of a light transmitting conductive film as the light transmitting film.

  The electro-optical device obtained by the manufacturing method according to the present invention is used as a direct-view display unit or the like in electronic devices such as a mobile phone or a mobile computer in addition to various light sources.

  Embodiments of the present invention will be described below. In the drawings to be referred to in the following description, the scales of the layers and the members are different from each other in order to make the layers and the members large enough to be recognized on the drawings. Note that in a thin film transistor, a source and a drain are switched depending on an applied voltage. However, in the following description, for convenience of explanation, a side to which a pixel electrode is connected will be described as a drain. Moreover, in the following description, the same code | symbol is attached | subjected and demonstrated to the part which bears a common function so that a response | compatibility with the structure demonstrated with reference to FIG. 11 may be understood easily.

[Embodiment 1]
FIG. 1 is a block diagram showing an electrical configuration of an electro-optical device according to Embodiment 1 of the present invention. 2A and 2B are a plan view of the electro-optical device to which the present invention is applied, viewed from the side of the counter substrate, together with each component formed thereon, and a JJ ′ cross-sectional view thereof. is there.

  An electro-optical device 100 shown in FIG. 1 is an organic EL device. On the element substrate 10, a plurality of scanning lines 3a, a plurality of data lines 6a extending in a direction intersecting the scanning lines 3a, and a scanning line are provided. The pixel region 10b is configured by a region in which the plurality of pixels 11 are arranged in a matrix. On the element substrate 10, a plurality of power supply lines 6g extend in parallel with the data lines 6a, and a plurality of capacitance lines 3e extend in parallel with the scanning lines 3a. A data line driving circuit 101 is connected to the data line 6a, and a scanning line driving circuit 104 is connected to the scanning line 3a. Each of the plurality of pixels 11 receives a switching thin film transistor 30b to which a scanning signal is supplied to the gate electrode via the scanning line 3a, and a pixel signal supplied from the data line 6a via the switching thin film transistor 30b. A holding capacitor 70 to hold, a driving thin film transistor 30c to which a pixel signal held by the holding capacitor 70 is supplied to the gate electrode, and the power line 6g when electrically connected to the power line 6g through the thin film transistor 30c An organic EL element 80 in which an organic functional layer is sandwiched between the first electrode layer 9a (pixel electrode / anode layer) into which the drive current flows from and the first electrode layer 9a and the second electrode layer 85 (cathode). And are configured. In the configuration shown in FIG. 1, the power supply line 6g and the capacitor line 3e extend from the data line driving circuit 101 and the scanning line driving circuit 104, respectively. However, since a constant potential is applied, A configuration in which the capacitor line 3e extends directly from the terminal 102 may be employed. In the configuration shown in FIG. 1, the capacitor line 3e is formed in parallel with the scanning line 3a, but the storage capacitor 70 is formed between the power supply line 6g and the drain of the thin film transistor 30b without forming the capacitor line 3e. You can also.

  In the electro-optical device 100, when the scanning line 3 a is driven and the switching thin film transistor 30 b is turned on, the potential of the data line 6 a at that time is held in the holding capacitor 70, and according to the charge held in the holding capacitor 70. The on / off state of the driving thin film transistor 30c is determined. Then, current flows from the power supply line 6g to the first electrode layer 9a through the channel of the driving thin film transistor 30c, and further current flows to the second electrode layer 85 through the organic functional layer. As a result, the organic EL element 80 emits light according to the amount of current flowing therethrough.

  2A and 2B, in the electro-optical device 100 of the present embodiment, the element substrate 10 and the sealing substrate 90 are bonded together by the sealing material 107, and the element substrate 10 and the sealing substrate 90 are interposed between each other. There is a filling layer 91 such as a translucent epoxy resin. In the element substrate 10, a data line driving circuit 101 and a terminal 102 made of an ITO film are provided along one side of the element substrate 10 in a region outside the sealing material 107, and the terminal 102 is arranged on the side where the terminal 102 is arranged. A scanning line driving circuit 104 is formed along two adjacent sides. On the remaining one side of the element substrate 10, a plurality of wirings 103 are provided for connecting between the scanning line driving circuits 104 provided on both sides of the image display region 10a. As will be described in detail later, an organic EL element 80 in which a first electrode layer, an organic functional layer, and a second electrode layer are laminated in this order is formed in a matrix on the element substrate 10. A structure in which the element substrate 10 is covered with a sealing resin without using the sealing substrate 90 may be employed.

(Detailed pixel configuration)
3A and 3B are a plan view of two adjacent pixels and a cross-sectional view of one pixel of the electro-optical device 100 according to Embodiment 3 of the present invention. 3B is a cross-sectional view taken along line BB ′ of FIG. 3A. In FIG. 3A, the first electrode layer 9a is indicated by a long dotted line, and is formed simultaneously with the data line 6a. The thin film is indicated by a one-dot chain line, the scanning line 3a is indicated by a solid line, and the semiconductor layer is indicated by a short dotted line.

  As shown in FIGS. 3A and 3B, a plurality of transparent first electrode layers 9a (regions surrounded by long dotted lines) are formed in a matrix on the element substrate 10 for each pixel 11. Data lines 6a (regions indicated by alternate long and short dashed lines), power supply lines 6g (regions indicated by alternate long and short dashed lines), scanning lines 3a (regions indicated by solid lines), and capacitance lines 3e (solid lines) along the vertical and horizontal boundary regions of the first electrode layer 9a. Are formed).

  As shown in FIG. 3B, in the element substrate 10, the base insulating layer 12 made of a silicon oxide film or the like is formed on the surface of the support substrate 10d as the base, and the first electrode layer is formed on the surface side. A thin film transistor 30c is formed in a region corresponding to 9a. In the thin film transistor 30c, a channel region 1g, a source region 1h, and a drain region 1i are formed with respect to the island-shaped semiconductor layer 1a. A gate insulating layer 2 is formed on the surface side of the semiconductor layer 1a, and a gate electrode 3f is formed on the surface of the gate insulating layer 2. The gate electrode 3f is electrically connected to the drain of the thin film transistor 30b. Note that the basic configuration of the thin film transistor 30b is the same as that of the thin film transistor 30c, and thus description thereof is omitted.

  On the upper layer side of the thin film transistor 30c, an interlayer insulating film 71 made of a silicon oxide film or a silicon nitride film, an interlayer insulating film 72 (flattening film) made of a thick photosensitive resin having a thickness of 1.5 to 2.0 μm, silicon A translucent insulating film 73 made of a nitride film or the like is formed. A data line 6a (not shown in FIG. 3B), a power supply line 6g and a drain electrode 6h are formed on the surface of the interlayer insulating film 71 (between the interlayer insulating films 71 and 72). The source region 1h is electrically connected through a contact hole 71g formed in the interlayer insulating film 71. The drain electrode 6h is electrically connected to the drain region 1i through a contact hole 71h formed in the interlayer insulating film 71. In this embodiment, the data line 6a, the power supply line 6g, and the drain electrode 6h are made of a single metal film such as a molybdenum film, an aluminum film, a titanium film, a tungsten film, a tantalum film, or a chromium film, or a laminated film thereof.

  A first electrode layer 9a made of an ITO film is formed on the surface of the translucent insulating film 73, and the first electrode layer 9a is interposed through contact holes 72g and 73g formed in the interlayer insulating films 72 and 73. The drain electrode 6h is electrically connected.

  A thick partition layer 5b made of a photosensitive resin or the like having an opening for defining a light emitting region is formed on the first electrode layer 9a. In the region surrounded by the partition wall layer 5b, a hole injection layer 81 made of 3,4-polyethylenediosithiophene / polystyrene sulfonic acid (PEDOT / PSS) or the like is formed on the first electrode layer 9a, and a light emitting layer An organic functional layer 82 is formed, and a second electrode layer 85 is formed on the light emitting layer 82. Thus, the organic EL element 80 is comprised by the 1st electrode layer 9a, the positive hole injection layer 81, the light emitting layer 82, and the 2nd electrode layer 85. FIG. The light-emitting layer 82 is made of, for example, a polyfluorene derivative, a polyphenylene derivative, polyvinylcarbazole, a polythiophene derivative, or a polymer material thereof. It is composed of a material doped with anthracene, tetraphenylbutadiene, Nile red, coumarin 6, quinacridone and the like. Further, as the light-emitting layer 82, a π-conjugated polymer material in which double-bonded π electrons are non-polarized on the polymer chain is also a conductive polymer, so that it is excellent in light-emitting performance. It is done. In particular, a compound having a fluorene skeleton in the molecule, that is, a polyfluorene compound is more preferably used. In addition to such materials, it is also possible to use a composition comprising a conjugated polymer organic compound precursor and at least one fluorescent dye for changing light emission characteristics. In this embodiment, the organic functional layer is formed by a coating method such as an inkjet method. As a coating method, a flexographic printing method, a spin coating method, a slit coating method, a die coating method, or the like may be employed. Moreover, when an organic functional layer consists of a low molecular material, an organic functional layer may be formed by a vapor deposition method etc. Further, an electron injection layer may be formed between the light emitting layer 82 and the second electrode layer 85.

  The electro-optical device 100 of the present embodiment is a top emission type organic EL device, and takes out light from the side on which the organic EL element 80 is formed as viewed from the support substrate 10d, as indicated by an arrow L1, so that the second electrode The layer 85 is formed as a translucent electrode such as a thin aluminum film or an ITO film with a work function adjusted by attaching a thin film such as magnesium or lithium. As the support substrate 10d, in addition to a transparent substrate such as glass, An opaque substrate can also be used. Examples of the opaque substrate include ceramics such as alumina, a metal plate such as stainless steel that has been subjected to an insulation treatment such as surface oxidation, and a resin substrate. When the electro-optical device 100 is a bottom emission type organic EL device, light is extracted from the support substrate 10d side, and therefore a transparent substrate such as glass is used as the support substrate 10d.

(Configuration of optical resonator structure)
FIG. 4 is an explanatory diagram schematically illustrating a state in which an optical resonator structure is formed in the first pixel, the second pixel, and the third pixel of the electro-optical device according to Embodiment 1 of the present invention.

  The electro-optical device 100 according to the present embodiment is a top emission type organic EL device, and among the light emitted from the organic EL element 80, the light directed toward the support substrate 10d is guided to the second electrode layer 85 side. There is a need. For this reason, in the electro-optical device 100, the region overlapping the first electrode layer 9a between the interlayer insulating film 72 and the light-transmitting insulating film 73 is made of a metal film such as aluminum, aluminum alloy, silver, or silver alloy. A light reflecting layer 4a is formed.

  Further, in the electro-optical device 100 of the present embodiment, as shown in FIG. 1, each of the plurality of pixels 11 includes a first pixel 11R for emitting red light (first wavelength light), green light (second wavelength). Of the second pixel 11G for emitting blue light (light of the third wavelength), and in this embodiment, the pixels 11 corresponding to the same color are A stripe arrangement linearly arranged in the extending direction of the data lines 6a is employed.

  For this reason, the first pixel 11R, the second pixel 11G, and the third pixel 11B are arranged in this order along the scanning line 3a, and this state is schematically shown in FIG. In FIG. 4, among the first pixel 11R, the second pixel 11G, and the third pixel 11B, the third pixel 11B has a contact hole 72g for connecting the first electrode layer 9a and the drain electrode 6h. 73g are also shown.

In the electro-optical device 100 configured as described above, the light emitted from the organic EL element 80 has a wide spectrum peak width and low intensity, and thus is sufficient when the electro-optical device 100 is used as a color display device. It is difficult to ensure accurate color reproducibility. Therefore, in the present embodiment, one of the layers positioned between the light reflecting layer 4a and the second electrode layer 85 is used as an optical distance adjustment layer, and the film thickness of the optical distance adjustment layer is as follows. First pixel 11R> second pixel 11G> third pixel 11B
And the optical distance between the light reflecting layer 4a and the second electrode layer 85 (refraction index of each layer × total thickness) is optimized, and the first pixel 11R, the second pixel 11G, An optical resonator structure optimum for each of the third pixels 11B is formed. That is, the resonance wavelength λ in the resonator structure is expressed by the following equation (2L) / λ + Φ / (2π) = m
As shown by the above, it is determined according to the optical distance L between the light reflecting layer 4a and the second electrode layer 85. “Φ (rad)” in the above equation is a phase shift that occurs at both ends of the resonator structure. More specifically, the phase shift Φ ₁ (rad) that occurs when the light is reflected by the light reflecting layer 4a This is the sum (Φ = Φ ₁ + Φ ₂ ) of the phase shifts Φ ₂ and (rad) that occur when reflecting by the two-electrode layer 85. “M” is an integer that makes the optical distance L positive. Accordingly, an optical for realizing optical resonance at the resonance wavelength λ by substituting the resonance wavelength λ of desired light to be emitted from the first pixel 11R, the second pixel 11G, and the third pixel 11B into the above equation. The target distance L is determined. Therefore, in this embodiment, the thickness of the translucent insulating film 73 in the first pixel 11R, the second pixel 11G, and the third pixel 11B is set to, for example, 100 nm, 70 nm, and 30 nm, respectively, and the first pixel 11R The optical distance L between the second pixel 11G and the third pixel 11B is optimized.

  For this reason, the light emitted from the light emitting layer 82 of the organic EL element 80 reflects light while reciprocating between the light reflecting layer 4a and the second electrode layer 85 facing each other across the light emitting layer 82. Since light having a resonance wavelength corresponding to the optical distance between the layer 4a and the second electrode layer 85 is selectively amplified, light having a narrow spectrum peak width and high intensity can be emitted from each pixel 11. .

In constructing such an optical resonator structure, in this embodiment, among the layers positioned between the light reflecting layer 4a and the second electrode layer 85, the translucent insulating film 73 is used as an optical distance adjusting layer. Thickness is related as follows: first pixel 11R> second pixel 11G> third pixel 11B
It is set to satisfy. Here, as will be described below with reference to FIGS. 6 and 7, the translucent insulating film 73 has a thickness of one layer of silicon nitride film that is the first pixel 11R, the second pixel 11G, and the third pixel 11B. The structure is changed in the above, and it does not have a multilayer structure.

(Production method)
FIGS. 5 and 6 are process cross-sectional views illustrating the method of manufacturing the electro-optical device 100 according to the first embodiment of the present invention. FIG. 5 illustrates a silicon nitride film for forming the translucent insulating film. FIG. 6 is a process cross-sectional view after the film formation until etching is performed on the formation region of the contact hole 73g, and FIG. It is process sectional drawing.

  In this embodiment, as shown in FIG. 5A, after the light reflecting layer 4a is formed, a light-transmitting insulating film 73 is formed on substantially the entire surface of the element substrate 10 by a CVD method or the like in the light-transmitting film forming step. A translucent film 73x made of a silicon nitride film is formed with a substantially constant film thickness.

Next, in the mask forming step shown in FIG. 5B, after forming the photosensitive resist layer 15x on the light transmitting film 73x by a spin coating method or the like, the photosensitive resist is formed using a multi-tone exposure mask. Gradation exposure is performed on the layer 15x with different exposure amounts for each region. Here, the exposure amount for the photosensitive resist layer 15x corresponds to the thickness of each region of the resist mask 15 to be described later with reference to FIG. 5C, and if the photosensitive resist layer 15x is a positive type, Exposure amount
If the first pixel 11R <second pixel 11G <third pixel 11B <contact hole 73g formation region and the photosensitive resist layer 15x is a negative type, the exposure amount is
First pixel 11R> second pixel 11G> third pixel 11B> contact hole 73g formation region. Therefore, when the photosensitive resist layer 15x is developed after the exposure, the resist mask 15 is formed on the transparent film 73x. The thickness of the resist mask 15 has the following relationship: first pixel 11R> second pixel 11G> The formation region of the third pixel 11B> contact hole 73g is satisfied. Here, the formation region of the contact hole 73g corresponds to a non-formation region of the translucent insulating film 73, and the thickness of the resist mask 15 in the formation region of the contact hole 73g is the first pixel 11R and the second pixel 11G. The resist mask 15 is not formed in the formation region of the contact hole 73g in the present embodiment as long as it is thinner than the third pixel 11B.

  Multi-tone exposure masks used for such gradation exposure include gray-tone masks and half-tone masks. In gray-tone masks, slits below the resolution of the exposure machine are formed, and the slits are part of the light. To achieve intermediate exposure. In contrast, a halftone mask uses a semi-transmissive film and performs intermediate exposure. In any case, the exposure level of “exposed portion”, “one or more intermediate exposed portions”, and “unexposed portion” can be realized by one exposure.

  Next, the removal process shown in FIGS. 5D to 6E is performed to remove the resist mask 15 from the surface side, and the portion of the light-transmitting film 73x exposed from the resist mask 15 is removed from the surface side. Thus, the translucent film 73x is left as an optical distance adjustment layer having a different thickness in the first pixel 11R, the second pixel 11G, and the third pixel 11B.

More specifically, first, in the etching process shown in FIG. 5D, since the resist mask 15 is not formed in the formation region of the contact hole 73g, the transparent mask 73x is exposed from the resist mask 15 in this state. Etch the exposed part. In this embodiment, when the transparent film 73x is etched, the resist mask 15 is not etched, and only the transparent film 73x is etched. Therefore, in this embodiment, dry etching using a chlorine-based etching gas or a fluorine-based etching gas such as SF ₆ is performed. As a result, the translucent film 73x is selectively etched only in the formation region of the contact hole 73g, and the thickness of the translucent film 73x is reduced in the formation region of the contact hole 73g.

  Next, in the ashing process shown in FIG. 6A, the resist mask is ashed from the surface side using oxygen plasma or the like, and only the thinnest part (the part formed in the third pixel 11B) in the resist mask 15 is obtained. Remove. As a result, in the third pixel 11B, the surface of the translucent film 73x is exposed. However, since the portions formed in the first pixel 11R and the second pixel 11G in the resist mask 15 are thick and the resist mask 15 remains, in the first pixel 11R and the second pixel 11G, the surface of the translucent film 73x is The film is covered with the resist mask 15.

Next, in the etching process shown in FIG. 6B, the transparent film 73x is exposed from the resist mask 15 by dry etching using a chlorine-based etching gas or a fluorine-based etching gas such as SF ₆ . Etch the part. As a result, the transparent film 73x is selectively etched only in the formation region of the first pixel 11R and the contact hole 73g, and the thickness of the transparent film 73x is reduced in the formation region of the first pixel 11R and the contact hole 73g. .

  Next, in the ashing step shown in FIG. 6C, the resist mask is ashed from the surface side using oxygen plasma or the like, and only the thinnest portion (the portion formed in the second pixel 11G) in the resist mask 15 is removed. Remove. As a result, in the second pixel 11G, the surface of the translucent film 73x is exposed. However, since the portion formed in the first pixel 11R in the resist mask 15 is thick and the resist mask 15 remains, the surface of the translucent film 73x is covered with the resist mask 15 in the first pixel 11R. .

Next, in the etching step shown in FIG. 6D, the light-transmitting film 73x is exposed from the resist mask 15 by dry etching using a chlorine-based etching gas or a fluorine-based etching gas such as SF _6. Etch the part. As a result, the translucent film 73x is selectively etched in the formation region of the first pixel 11R, the second pixel 11G, and the contact hole 73g, and the film thickness of the translucent film 73x in the first pixel 11R and the second pixel 11G. Becomes thinner. Further, a contact hole 73g made of a through hole is formed in the contact hole 73g formation region.

Next, in the ashing step shown in FIG. 6E, the remaining resist mask 15 is removed by ashing using oxygen plasma or the like. As a result, the translucent film 73x remains on the element substrate 10 as the translucent insulating film 73 (optical distance adjusting layer), and the film thickness has the following relationship: first pixel 11R> second pixel 11G> third Pixel 11B
Will be satisfied. That is, the thickness of the transparent film 73x formed first is t0, the etching depth in the etching process shown in FIG. 6B is D2, and the etching depth in the etching process shown in FIG. When D3, the thickness of the translucent insulating film 73 in each pixel 11 is the following value: Thickness of the translucent insulating film 73 in the first pixel 11R = t0
Thickness of the translucent insulating film 73 in the second pixel 11G = t0−D3
Thickness of the translucent insulating film 73 in the third pixel 11B = t0−D2−D3
It becomes. Further, when the etching depth in the etching step shown in FIG. 5D is D1, the following relationship is obtained: t0 = D1 + D2 + D3 = depth of the contact hole 73g where the transparent film 73x is formed.

Thereafter, an ITO film is formed on the surface of the light-transmitting insulating film 73, and then the ITO film is patterned using a photolithography technique to form the first electrode layer 9a in each of the plurality of pixels 11. Thereafter, as shown in FIG. 4, a hole injection layer 81, a light emitting layer 82, and a second electrode layer 85 are sequentially formed. As a result, the optical distance between the light reflecting layer 4a and the second electrode layer 85 has the following relationship: first pixel 11R> second pixel 11G> third pixel 11B
An optical resonator structure that is optimal for the first pixel 11R, the second pixel 11G, and the third pixel 11B is configured.

When such a manufacturing method is adopted, the transparent film 73x is completely removed in the formation region of the contact hole 73g, and the drain electrode 6h is exposed at the bottom of the contact hole 73g. At this time, since the surface of the drain electrode 6h is exposed to the etching gas, from the viewpoint of ensuring electrical connection between the drain electrode 6h and the first electrode layer 9a, in the etching process, the light transmission is performed. It is preferable to set materials and etching conditions of the light-transmitting film 73x and the drain electrode 6h so as to have a high etching selectivity between the film 73x and the drain electrode 6h. Therefore, in this embodiment, the drain electrode 6h is composed of a single layer film of titanium or a laminated film having a titanium layer on the surface, and the etching gas is, for example, 100 sccm of SF ₆ gas and 100 sccm of O ₂ gas. RIE (Reactive Ion Etching / Reactive Ion Etching) mode is realized using mixed gas. Further, the thicknesses of the translucent insulating film 73 in the first pixel 11R, the second pixel 11G, and the third pixel 11B are 100 nm, 70 nm, and 30 nm, respectively, and the thickness of the titanium portion in the drain electrode 6h is 100 nm. It is set above. For this reason, when the light-transmitting film 73x is completely etched, the drain electrode 6h remains reliably at the bottom of the contact hole 73g, so that the first electrode layer 9a and the drain electrode 6h can be reliably connected.

(Main effects of this form)
As described above, in the present embodiment, in configuring an optical resonator structure optimal for the first pixel 11R, the second pixel 11G, and the third pixel 11B, the translucent film 73x for configuring the optical distance adjustment layer is provided. The light-transmitting film forming step to be formed, the mask forming step for forming the resist mask 15 having a different film thickness for each pixel 11, and the removing step for removing the resist mask 15 and the light-transmitting film 73x from the surface side are performed. Good. Therefore, the productivity of the electro-optical device 100 can be improved.

  In addition, since the optical distance adjustment layer can be formed by a single light-transmitting film 73x, unlike the case where the optical distance adjustment layer is formed by a plurality of layers, unnecessary reflection in the optical distance adjustment layer. Will not occur. Furthermore, when forming the optical distance adjustment layer, it is not necessary to repeat the film forming process and the patterning process using the photolithography technique, thereby avoiding the occurrence of problems that occur when performing a plurality of patterning processes. Can do.

  Further, in this embodiment, since the resist mask 15 is formed by gradation exposure in the mask formation process, a mask having a different thickness for each pixel can be formed in one exposure process, and the electro-optical device 100 is produced. Can be improved.

  Furthermore, in this embodiment, in the light transmissive film forming step, the light transmissive film 73x is also formed in the non-formation region (formation region of the contact hole 73g) of the light transmissive insulating film 73 (optical distance adjustment layer), and the pixel 11 When forming the translucent insulating film 73 having a different thickness every time, the translucent film 73x on the non-formation region is completely removed. Therefore, since it is not necessary to form the contact hole 73g in a separate process, the productivity of the electro-optical device 100 can also be improved in this respect.

[Embodiment 2]
FIG. 7 is an explanatory diagram schematically illustrating a state in which an optical resonator structure is formed in the first pixel 11R, the second pixel 11G, and the third pixel 11B of the electro-optical device according to the second embodiment of the invention. . FIG. 8 shows the manufacturing process of the electro-optical device 100 according to the second embodiment of the present invention. After forming the ITO film for forming the first electrode layer 9a, the thickness of the ITO film is set to the first pixel. It is process sectional drawing which shows the process until it changes with 11R, 2nd pixel 11G, and 3rd pixel 11B. The basic configuration of the present embodiment is the same as that of the first embodiment, and therefore, common portions will be described with the same reference numerals.

In the first embodiment, the first pixel 11R for emitting red light (first wavelength light), the second pixel 11G for emitting green light (second wavelength light), and blue light (third light). In constructing the optimum optical resonator structure for the third pixel 11B for emitting the light (wavelength light), the light-transmitting insulating film 73 is used as the optical distance adjusting layer. As described above, the first electrode layer 9a made of an ITO film is used as an optical distance adjusting layer, and the film thickness of the first electrode layer 9a is represented by the following relationship: first pixel 11R> second pixel 11G> third pixel 11B
It is set to satisfy. Here, the first electrode layer 9a has a configuration in which the thickness of the ITO film of one layer of the first pixel 11R, the second pixel 11G, and the third pixel 11B is changed, and does not have a multilayer structure. The translucent insulating film 73 has the same film thickness in the first pixel 11R, the second pixel 11G, and the third pixel 11B.

  In manufacturing the electro-optical device 100 having such a structure, in this embodiment, as shown in FIG. 8A, after forming the light-transmitting insulating film 72, the light-transmitting film forming step is performed by sputtering or the like. A translucent film 9 made of an ITO film for forming the first electrode layer 9a is formed on a substantially entire surface of the substrate 10 with a substantially constant film thickness.

Next, a mask formation process is performed. For this purpose, after forming the photosensitive resist layer 15x on the upper layer of the light-transmitting film 9 by a spin coat method or the like, gradation exposure is performed to expose the photosensitive resist layer 15x with different exposure amounts for each region, and development is performed. A resist mask 15 shown in FIG. 8B is formed. The thickness of the resist mask 15 satisfies the following relationship: first pixel 11R> second pixel 11G> third pixel 11B <first electrode layer 9a. Here, the thickness of the resist mask 15 in the region between the first electrode layers 9a only needs to be thinner than the first pixel 11R, the second pixel 11G, and the third pixel 11B. In this embodiment, the first electrode layer The resist mask 15 is not formed in the region between 9a.

  Next, as shown in FIGS. 8C to 8F, the resist mask 15 is removed from the surface side, and a portion of the light transmissive film 9 exposed from the resist mask 15 is removed from the surface side to remove the light transmissive film. A removal step is performed in which 9 is left as the first electrode layer 9a (optical distance adjustment layer) having a different thickness in the first pixel 11R, the second pixel 11G, and the third pixel 11B.

  Since the removal process is the same as that of the first embodiment, a detailed description is omitted. First, in the etching process shown in FIG. 8C, a portion of the light-transmitting film 9 exposed from the resist mask 15 is first illustrated. Etching is performed to reduce the thickness of the translucent film 9 corresponding to the portion between the first electrode layers 9a.

  Next, as shown in FIG. 8D, in the ashing process, the resist mask 15 is ashed from the surface side, and the thinnest part of the resist mask 15 (the part formed in the third pixel 11B) is removed. After exposing the surface of the light transmissive film 9 in the third pixel 11B, the surface of the light transmissive film 9 exposed from the resist mask 15 is etched in the etching process.

  Next, as shown in FIG. 8E, in the ashing process, the resist mask 15 is ashed from the surface side, and the thinnest part of the resist mask 15 (the part formed in the second pixel 11G) is removed. After exposing the surface of the light-transmitting film 9 in the second pixel 11G, the surface of the light-transmitting film 9 exposed from the resist mask 15 is etched in the etching process.

Next, as shown in FIG. 8F, the remaining resist mask 15 is removed by ashing. As a result, the translucent film 9 remains on the element substrate 10 as the first electrode layer 9a (optical distance adjustment layer), and the film thickness has the following relationship: first pixel 11R> second pixel 11G> third pixel 11B
Meet.

Thereafter, as shown in FIG. 7, the hole injection layer 81, the light emitting layer 82, and the second electrode layer 85 are sequentially formed. As a result, the optical distance between the light reflecting layer 4a and the second electrode layer 85 has the following relationship: first pixel 11R> second pixel 11G> third pixel 11B
An optical resonator structure that is optimal for the first pixel 11R, the second pixel 11G, and the third pixel 11B is configured.

  As described above, in the present embodiment as well, in the same way as in the first embodiment, in constructing the optimum optical resonator structure for the first pixel 11R, the second pixel 11G, and the third pixel 11B, the optical distance adjustment layer is configured. A translucent film forming step for forming the optical film 9, a mask forming step for forming a resist mask 15 having a different thickness for each pixel 11, and a removing step for removing the resist mask 15 and the translucent film 9 from the surface side. You just need to do. Therefore, the same effects as those of the first embodiment can be achieved, such as the productivity of the electro-optical device 100 being improved.

[Embodiment 3]
FIG. 9 shows the manufacturing process of the electro-optical device 100 according to the third embodiment of the present invention. After forming the ITO film for forming the first electrode layer 9a, the thickness of the ITO film is set to the first pixel. It is process sectional drawing which shows the process until it changes with 11R, 2nd pixel 11G, and 3rd pixel 11B. The basic configuration of the present embodiment is the same as that of the second embodiment, and therefore common portions will be described with the same reference numerals.

  In the first and second embodiments, the ashing process for the resist mask and the etching process for the light-transmitting film are alternately performed as the removing process, but in this embodiment, the resist mask and the light-transmitting film are described as follows. Both are dry-etched under conditions that allow etching.

  Specifically, as in the first embodiment, first, as shown in FIG. 9A, after forming the translucent insulating film 72, in the translucent film forming step, the element substrate 10 is formed by sputtering or the like. A light-transmitting film 9 made of an ITO film for constituting the first electrode layer 9a is formed on the substantially entire surface of the film with a substantially constant film thickness.

Next, a mask formation process is performed. For this purpose, after forming the photosensitive resist layer 15x on the upper layer of the light-transmitting film 9 by a spin coat method or the like, gradation exposure is performed to expose the photosensitive resist layer 15x with different exposure amounts for each region, and development is performed. A resist mask 15 shown in FIG. 9B is formed. The thickness of the resist mask 15 satisfies the following relationship: first pixel 11R> second pixel 11G> third pixel 11B> first electrode layer 9a. Here, the thickness of the resist mask 15 in the region between the first electrode layers 9a only needs to be thinner than the first pixel 11R, the second pixel 11G, and the third pixel 11B. In this embodiment, the first electrode layer The resist mask 15 is not formed in the region between 9a.

  Next, as shown in FIGS. 9C to 9E, both the resist mask and the translucent film are dry-etched under conditions that allow etching, and the resist mask 15 is removed from the surface side. 9, the portion exposed from the resist mask 15 is removed from the surface side, and the first electrode layer 9 a (optical distance adjustment) of the translucent film 9 having different thicknesses in the first pixel 11 R, the second pixel 11 G, and the third pixel 11 B The removal process which remains as a layer is performed.

  More specifically, the resist mask 15 and the translucent film 9 are simultaneously etched from the surface side by dry etching using an etching gas containing a halogen-based gas as a main component. As a result, as shown in FIG. 9C, the surface of the light-transmitting film 9 exposed from the resist mask 15 in the region between the first electrode layers 9a is etched, and the resist mask 15 is also exposed to the surface. Thus, the resist mask 15 is removed in the third pixel 11B, and the surface of the light-transmitting film 9 is exposed in the third pixel 11B.

  Subsequently, as shown in FIG. 9D, the translucent film 9 is etched from the surface in the region between the third pixel 11B and the first electrode layer 9a, and the surface of the resist mask 15 is also etched. Therefore, the resist mask 15 is removed in the second pixel 11G, and the surface of the translucent film 9 is exposed in the second pixel 11G. Subsequently, as shown in FIG. 9E, the translucent film 9 is etched from the surface in the region between the second pixel 11G, the third pixel 11B, and the first electrode layer 9a, and the resist mask 15 is also formed. Since the surface is etched, the resist mask 15 is removed from the first pixel 11R.

As a result, the translucent film 9 remains on the element substrate 10 as the first electrode layer 9a (optical distance adjustment layer), and the film thickness has the following relationship: first pixel 11R> second pixel 11G> third pixel 11B
Meet.

Thereafter, as shown in FIG. 7, the hole injection layer 81, the light emitting layer 82, and the second electrode layer 85 are sequentially formed. As a result, the optical distance between the light reflecting layer 4a and the second electrode layer 85 has the following relationship: first pixel 11R> second pixel 11G> third pixel 11B
An optical resonator structure that is optimal for the first pixel 11R, the second pixel 11G, and the third pixel 11B is configured.

  As described above, in the present embodiment as well, in the same way as in the first embodiment, in constructing the optimum optical resonator structure for the first pixel 11R, the second pixel 11G, and the third pixel 11B, the optical distance adjustment layer is configured. A translucent film forming step for forming the optical film 9, a mask forming step for forming a resist mask 15 having a different thickness for each pixel 11, and a removing step for removing the resist mask 15 and the translucent film 9 from the surface side. You just need to do. Therefore, the same effects as those of the first embodiment can be achieved, such as the productivity of the electro-optical device 100 being improved.

  Further, in this embodiment, in the removing process shown in FIGS. 9A to 9E, since the dry etching is performed under the condition that both the resist mask 15 and the light-transmitting film 9 can be etched, the resist mask 15 is removed. The removal of the light-transmitting film 9 between the first electrode layers 9a and the adjustment of the thickness of the first electrode layer 9a in each pixel 11 can be performed continuously, and the productivity can be improved.

  The configuration according to this embodiment can also be applied to the first embodiment described with reference to FIG. 4 and the like. In this case, dry etching is performed under the condition that both the resist mask 15 and the translucent film 73x can be etched. Then, the resist mask 15 is removed, the contact hole 73g is formed, and the thickness a of the translucent insulating film 73 in each pixel 11 is adjusted continuously.

[Another embodiment]
In the above embodiment, the top emission type organic EL device has been described as the electro-optical device 100 to which the present invention is applied. However, the present invention may be applied to a bottom emission type organic EL device. In the above embodiment, as an electro-optical device to which the present invention is applied, a first pixel for emitting red light (first wavelength light) and a green light (second wavelength light) are emitted. The second pixel and the third pixel for emitting blue light (third wavelength light) have been described as examples. However, the emission color and the number of emission colors are not limited to these, and the electro-optic having at least three emission colors. Any device can be used. The present invention is not limited to an organic EL device, and may be applied to the case where an optical resonator structure is formed in an electro-optical device including a liquid crystal device, various sensors, a semiconductor circuit, and a composite thereof.

[Example of mounting on electronic equipment]
Next, an electronic apparatus to which the electro-optical device 100 according to the above-described embodiment is applied will be described. FIG. 10A shows a configuration of a mobile personal computer including the electro-optical device 100. The personal computer 2000 includes an electro-optical device 100 as a display unit and a main body 2010. The main body 2010 is provided with a power switch 2001 and a keyboard 2002. FIG. 10B shows the configuration of a mobile phone provided with the electro-optical device 100. A cellular phone 3000 includes a plurality of operation buttons 3001, scroll buttons 3002, and the electro-optical device 100 as a display unit. By operating the scroll button 3002, the screen displayed on the electro-optical device 100 is scrolled. FIG. 10C shows the configuration of a personal digital assistant (PDA) to which the electro-optical device 100 is applied. The information portable terminal 4000 includes a plurality of operation buttons 4001, a power switch 4002, and the electro-optical device 100 as a display unit. When the power switch 4002 is operated, various types of information such as an address book and a schedule book are displayed on the electro-optical device 100.

  Note that electronic devices to which the electro-optical device 100 is applied include, in addition to those shown in FIG. 10, a digital still camera, a liquid crystal television, a viewfinder type, a monitor direct-view type video tape recorder, a car navigation device, a pager, an electronic notebook, Examples include calculators, word processors, workstations, videophones, POS terminals, devices with touch panels, and the like. The electro-optical device 100 described above can be applied as a display unit of these various electronic devices.

1 is an equivalent circuit diagram showing an electrical configuration of an element substrate used in an electro-optical device (organic EL device) according to Embodiment 1 of the present invention. (A), (b) is the top view which looked at the electro-optical apparatus based on Embodiment 1 of this invention from the opposing board | substrate side with each component formed on it, respectively, and its JJ 'cross section FIG. FIGS. 4A and 4B are a plan view of two adjacent pixels and a cross-sectional view of one pixel of the electro-optical device according to the first embodiment of the present invention. FIG. 6 is an explanatory diagram schematically illustrating a state in which an optical resonator structure is formed in the first pixel, the second pixel, and the third pixel of the electro-optical device according to the first embodiment of the invention. Of the manufacturing process of the electro-optical device according to the first embodiment of the present invention, the process cross section from the formation of the silicon nitride film for forming the translucent insulating film to the etching of the contact hole formation region FIG. FIG. 6 is a process cross-sectional view of the electro-optical device manufacturing process according to Embodiment 1 of the present invention, after the first ashing process is performed on the resist mask and before the first electrode is formed. FIG. 6 is an explanatory diagram schematically illustrating a state in which an optical resonator structure is formed in the first pixel, the second pixel, and the third pixel of the electro-optical device according to Embodiment 2 of the invention. In the manufacturing process of the electro-optical device according to the second embodiment of the present invention, after forming the ITO film for forming the first electrode, the thickness of the ITO film is set to the first pixel, the second pixel, and the first pixel. It is process sectional drawing which shows the process until it changes by 3 pixels. In the manufacturing process of the electro-optical device according to the third embodiment of the present invention, after forming the ITO film for forming the first electrode, the thickness of the ITO film is set to the first pixel, the second pixel, and the first pixel. It is process sectional drawing which shows the process until it changes by 3 pixels. It is explanatory drawing of the electronic device using the electro-optical apparatus which concerns on this invention. It is explanatory drawing which shows typically a mode that the optical resonator structure was formed in the 1st pixel, 2nd pixel, and 3rd pixel of the conventional electro-optical apparatus.

Explanation of symbols

3a..Scanning line, 6a..Data line, 9, 73x..Translucent film, 9a..First electrode, 10..Element substrate, 11..Pixel, 11R..First pixel, 11G..No. 2 pixels, 11B .. 3rd pixel, 15 .. Eist mask, 30b, 30c .. Thin film transistor (pixel transistor), 73 .. Translucent insulating film, 80 .. Organic EL element, 100 .. Electro-optical device

Claims (9)

At least a first pixel for emitting light of a first wavelength, a second pixel for emitting light of a second wavelength shorter than the first wavelength, and a first pixel shorter than the first wavelength and the second wavelength. A third pixel for emitting light of three wavelengths,
Each of the first pixel, the second pixel, and the third pixel has an optical film thickness adjustment layer that satisfies the following relationship: an optical distance adjustment layer that satisfies the first pixel> the second pixel> the third pixel. In a method for manufacturing an electro-optical device having a structure,
In forming the optical distance adjustment layer,
A translucent film forming step of forming a translucent film for configuring the optical distance adjustment layer for the first pixel, the second pixel, and the third pixel;
A mask forming step of forming a mask on the upper layer of the translucent film so that the film thickness satisfies the following relationship: the first pixel> the second pixel> the third pixel;
The mask is removed from the surface side, and a portion of the light transmissive film exposed from the mask is removed from the surface side so that the light transmissive film is different between the first pixel, the second pixel, and the third pixel. A method of manufacturing an electro-optical device, comprising performing a removal step of leaving the film as the optical distance adjustment layer having a film thickness.   In the mask forming step, after a photosensitive resist layer is formed on the transparent film, gradation exposure is performed to expose the photosensitive resist layer with a different exposure amount for each region, and then development is performed. A method of manufacturing an electro-optical device according to claim 1, wherein a resist mask is formed as the mask. In the translucent film forming step, the translucent film is formed also in a non-formation region of the optical distance adjustment layer,
In the mask formation step, the mask is formed on the upper layer of the translucent film so that the film thickness satisfies the following relationship: the third pixel> the non-formation region,
3. The method of manufacturing an electro-optical device according to claim 1, wherein in the removing step, the translucent film on the non-formation region is completely removed.   In the removing step, the mask is removed from the surface side to remove a thinnest portion of the mask to expose a part of the surface of the light transmissive film, and the light transmissive film includes the ashing step. 4. The method of manufacturing an electro-optical device according to claim 1, wherein etching steps for removing portions exposed from the mask from the surface side are alternately performed at least twice. 5.   4. The method of manufacturing an electro-optical device according to claim 1, wherein in the removing step, dry etching is performed under a condition in which both the mask and the light-transmitting film can be etched. 5. In each of the first pixel, the second pixel, and the third pixel, at least a light reflection layer, a first electrode layer, a light emitting layer of an organic electroluminescence element, and a second electrode layer are sequentially stacked on the substrate. ,
2. The first pixel, the second pixel, and the third pixel each have the optical resonator structure between the light reflecting layer and the second electrode layer. The method for manufacturing an electro-optical device according to any one of claims 1 to 5.   The optical distance adjusting layer is formed of a light-transmitting insulating film formed as the light-transmitting film after forming the light reflecting layer and before forming the first electrode layer. A method for manufacturing the electro-optical device according to claim 1.   The method of manufacturing an electro-optical device according to claim 6, wherein the optical distance adjustment layer is the first electrode layer made of a light-transmitting conductive film as the light-transmitting film.   An electro-optical device obtained by the manufacturing method according to claim 1.

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