JP2016162583A - Electro-optic device and electronic apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electro-optic device and an electronic apparatus in which emission unevenness can be reduced by suppressing variation of the thickness in a pixel.SOLUTION: An electro-optic device includes: a substrate; a drive element part provided on the substrate; a ground layer covering the drive element part; a partition provided on the ground layer; a plurality of pixel regions sectioned by the ground layer and the partition; a functional layer disposed in the pixel region and formed by applying a functional fluid; and a step reduction auxiliary layer disposed on or in the ground layer, and reducing a step occurring in the pixel region due to the drive element part.SELECTED DRAWING: Figure 3

Description

  The present invention relates to an electro-optical device and an electronic apparatus.

  In recent years, an electro-optical device using a light emitting element called an organic light emitting diode (OLED) such as an organic electroluminescent (EL) element or a light emitting polymer element has been developed. In addition, since the organic EL element is a self-luminous type, it is not only highly visible, but also thin and light, and has excellent impact resistance, and thus has attracted attention as a display device that replaces a liquid crystal display device ( For example, see Patent Documents 1 to 3).

JP 2014-123540 A JP 2008-41894 A JP 2008-41747 A

  By the way, recently, an organic EL element is formed of a coating film by using a droplet discharge method that can be patterned finely and easily without waste of materials. However, when the droplet discharge method is used in this way, the film thickness of the organic functional layer (coating film) may vary within the pixel due to the influence of the step in the lower layer. If the film thickness varies in the pixel, there is a possibility that uneven light emission occurs and the display quality deteriorates.

  The present invention has been made in view of such circumstances, and an object thereof is to provide an electro-optical device and an electronic apparatus that can suppress variations in the film thickness of a pixel and reduce unevenness in light emission. .

  According to the first aspect of the present invention, a substrate, a drive element unit provided on the substrate, a base layer covering the drive element unit, a partition provided on the base layer, the base layer, and the base layer A plurality of pixel regions partitioned by partition walls, a functional layer disposed in the pixel region and formed by a droplet discharge method, and disposed on the base layer or in the base layer. An electro-optical device is provided that includes a step relief assisting layer that relaxes a step occurring in the region.

  According to the electro-optical device according to the first aspect, the step generated in the pixel region is reduced by the step reduction assisting layer, so that the thickness of the functional layer formed by the droplet discharge method can be made uniform. Therefore, variation in the inner film thickness of the pixel can be suppressed and light emission unevenness can be reduced.

In the electro-optical device, it is preferable that the base layer has a laminated structure including at least one interlayer film.
According to this structure, the structure which arrange | positions a level | step difference mitigation auxiliary layer inside a base layer can be easily implement | achieved by arrange | positioning a level | step difference mitigation auxiliary layer between laminated structures.

In the electro-optical device, it is preferable that the drive element unit includes at least one wiring layer, and the step relaxation assisting layer includes a first relaxation layer formed of the same material as the wiring layer.
According to this configuration, the step relief assisting layer can be formed simultaneously in the process of forming the wiring layer of the drive element portion.

In the electro-optical device, it is preferable that the step relief assisting layer includes a second relaxation layer formed of a material different from that of the wiring layer.
According to this configuration, an optimal material can be selected when forming the second relaxation layer. In addition, since the degree of freedom in layout is increased by forming in a separate process, a step generated in the pixel region can be favorably mitigated.

In the electro-optical device, it is preferable that the second relaxation layer is formed of an insulating material.
According to this configuration, the second relaxation layer can be brought into contact with the conductive drive element portion. Therefore, the step generated between the wirings can be satisfactorily eased by forming the second relaxation layer so as to fill the recesses generated between the wiring layers.

In the electro-optical device, in the case where the step relaxation assisting layer includes the first relaxation layer and the second relaxation layer, the second relaxation layer has a film thickness as compared with the first relaxation layer. Is preferably thick.
According to this configuration, for example, when the second relaxation layer made of an insulating material is disposed between the electrodes, the distance between the electrodes can be increased, so that the parasitic capacitance can be reduced.

In the electro-optical device, it is preferable that the second relaxing layer has a dot shape or a stripe shape in plan view.
According to this configuration, for example, when the second relaxation layer made of an insulating material is disposed between the electrodes, the surface area can be reduced, so that the parasitic capacitance can be reduced.

In the electro-optical device, when the step relaxation assisting layer includes the first relaxation layer and the second relaxation layer, the predetermined step is relaxed only by the first relaxation layer, and The first relaxing layer may be thicker than the wiring layer.
Alternatively, when the step relaxation assisting layer includes the first relaxation layer and the second relaxation layer, the predetermined step is relaxed only by the second relaxation layer, and the second relaxation layer May be thicker than the wiring layer.
Alternatively, in the case where the step relaxation assisting layer includes the first relaxation layer and the second relaxation layer, the step is relaxed by the first relaxation layer and the second relaxation layer, and the first One relaxing layer may be thicker than the wiring layer.
Alternatively, when the step relaxation assisting layer includes the first relaxation layer and the second relaxation layer, the predetermined step is relaxed by the first relaxation layer and the second relaxation layer, and The second relaxation layer is thicker than the wiring layer. According to this configuration, it is possible to satisfactorily relax the step generated in the pixel region.

  According to the second aspect of the present invention, an electronic apparatus including the electro-optical device according to the first aspect is provided.

  According to the electronic apparatus according to the second aspect, since the electro-optical device according to the first aspect is provided, the electronic apparatus has high display quality and high reliability.

FIG. 3 is a schematic diagram illustrating a circuit configuration of an electro-optical device. The perspective plan view which shows the planar structure of a pixel area. The figure which shows the cross-section of a pixel area. Explanatory drawing of the tolerance | permissible_range of the level | step difference height and taper angle in a base layer. (A), (b) is a figure which shows the structure of an inkjet head. The figure which shows the cross-section of the pixel area | region which concerns on 2nd Embodiment. (A)-(c) is a figure which shows the shape of the 2nd level | step difference mitigation auxiliary layer which concerns on a modification. The figure which shows the cross-sectional structure of the pixel electrode peripheral part which concerns on a modification. The perspective view which shows an example of a mobile telephone. The perspective view which shows an example of a wristwatch. The perspective view which shows an example of a portable information processing apparatus.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
In addition, in the drawings used in the following description, in order to make the features easy to understand, there are cases where the portions that become the features are enlarged for the sake of convenience, and the dimensional ratios of the respective components are not always the same as the actual ones. Absent. In addition, the materials, dimensions, and the like exemplified in the following description are examples, and the present invention is not necessarily limited thereto, and can be appropriately changed and implemented without departing from the scope of the invention. .

(Electro-optical device)
First, a circuit configuration of the electro-optical device 1 shown in FIG. 1 will be described as an embodiment of the present invention. FIG. 1 is a schematic diagram illustrating a circuit configuration of the electro-optical device 1.

  As shown in FIG. 1, the electro-optical device 1 includes a plurality of scanning lines 101 arranged at a predetermined interval on the surface of the substrate 100, and a direction intersecting the plurality of scanning lines 101 at a substantially right angle with a space therebetween. Wiring including a plurality of signal lines 102 arranged at predetermined intervals and a plurality of power supply lines 103 arranged at predetermined intervals in a direction substantially parallel to the signal lines 102 with a space therebetween. A plurality of pixel regions A are provided in a matrix in the vicinity of the intersections of the plurality of scanning lines 101 and the plurality of signal lines 102.

  Each signal line 102 is connected to a signal side drive circuit 104 including a shift register, a level shifter, a video line, and an analog switch. Each scanning line 101 is connected to a scanning side drive circuit 105 having a shift register and a level shifter.

  In each pixel region A, a switching TFT 106 to which a scanning signal is supplied via the scanning line 101, a holding capacitor 107 for holding a pixel signal supplied from the signal line 102 via the switching TFT 106, and this holding A driving TFT 108 to which a pixel signal held by the capacitor 107 is supplied; a pixel electrode (anode) 109 into which a driving current flows from the power supply line 103 when electrically connected to the power supply line 103 via the driving TFT 108; A counter electrode (cathode) 110 facing the pixel electrode 109 and a functional layer 10 sandwiched between the pixel electrode 109 and the counter electrode 110 are provided.

  In the electro-optical device 1 having the above configuration, when the scanning line 101 is driven and the switching TFT 106 is turned on, the potential of the signal line 102 at that time is held in the holding capacitor 107. The on / off state of the driving TFT 108 is determined according to the state of the storage capacitor 107. Then, a current flows from the power supply line 103 to the pixel electrode 109 via the channel of the driving TFT 108, and further a current flows to the counter electrode (cathode) 110 via the functional layer 10. The functional layer 10 emits light according to the amount of current that flows. A desired image can be displayed by controlling the light emission in the pixel region A.

The electro-optical device 1 includes a bottom emission structure that extracts light from the substrate 100 side and a top emission structure that extracts light from the side opposite to the substrate 100.
In recent years, electro-optical devices are required to have high definition in all applications such as TVs, tablets, and smartphones. In this way, when the image becomes high definition, the pixel aperture ratio is lowered, and there is a risk of deteriorating the quality such as a reduction in display brightness. In the electro-optical device 1 of the present embodiment, a top emission structure is adopted in order to solve this problem. As a result, the pixel area A can be formed on the wiring to increase the aperture ratio.

  Next, a specific structure in the pixel region A of the electro-optical device 1 will be described with reference to FIGS. 2 is a perspective plan view showing a planar structure of the pixel area A. FIG. FIG. 3 is a cross-sectional view schematically showing a typical cross-sectional structure in a cross-sectional shape of the pixel region A as a single view, and represents the difference in height between the cross-sectional structures that occurs in the pixel region A. It is a thing. In FIG. 3, the sealing substrate is not shown.

  The electro-optical device 1 of this embodiment is an example in which a top emission structure is employed, and a glass substrate is used as the substrate 100. When the top emission structure is employed, the substrate 100 is not limited to a glass substrate, but is a substrate made of a semiconductor material (single crystal Si, Ga, Ge, etc.), a ceramic material, a metal material, or the like that does not have optical transparency. Can be used.

  Specifically, as shown in FIGS. 2 and 3, the electro-optical device 1 includes a driving element unit 11 and a base layer 30 that includes the driving element unit 11 and covers the substrate surface 100 a on the surface of the substrate 100 described above. And the functional element portion 12 are sequentially stacked.

  The drive element unit 11 includes the various wirings 101 to 103 shown in FIG. 1 formed on the surface of the substrate 100, the switching TFT 106, the storage capacitor 107, the drive TFT 108, and the like. In the present embodiment, the drive element unit 11 is disposed in the peripheral part of each pixel region A (see FIG. 2). That is, each pixel region A has a high flatness at the center portion.

  The driving TFT 108 has a semiconductor layer 17 formed on the surface of the substrate 100, a gate electrode 13, a source electrode 14, and a drain electrode 15. The gate electrode 13 is electrically connected to the drain electrode (not shown) of the switching TFT 106. A gate electrode 13 is provided on the semiconductor layer 17 via a gate insulating film 16.

  The source electrode 14 and the drain electrode 15 are electrically connected to the source region and the drain region of the semiconductor layer 17 through contact plugs 16 a and 16 b formed in the gate insulating film 16.

  On the gate insulating film 16, first layer metals 11 </ b> A <b> 1 and 11 </ b> A <b> 2 constituting the driving element unit 11 are disposed in addition to the gate electrode 13. The first layer metal 11A1 includes the components of the drive element unit 11 (for example, a part of the wirings 101 to 103 shown in FIG. 1). The first layer metal 11A2 constitutes a capacitor electrode of the storage capacitor 107, for example.

  In the present embodiment, the drive element unit 11 is arranged in the peripheral region of the opening 40 in the pixel region A. Therefore, in the peripheral region of the opening 40, the above-described various wirings 101 to 103, the storage capacitor 107, and the like are three-dimensionally overlapped.

  For example, when the power supply line 103 is a two-layer wiring in order to suppress the specific resistance of the power supply line 103 or when the line width of the wiring is narrowed for high definition, the height dimension of the power supply line 103 is reduced. Will increase further. In this case, the base layer 30 is likely to have a step in the peripheral region of the opening 40 (pixel region A) that covers the drive element unit 11.

  In the present embodiment, the step difference is eased by disposing the step relief assisting layer 35 in a region where a large step is caused by the drive element portion 11 in the base layer 30. Thereby, the film thickness uniformity of the pixel electrode 109 formed on the base layer 30 and the functional layer 10 formed on the pixel electrode 109 is improved.

In the present embodiment, the functional layer 10 is formed using a droplet discharge method as described later. In the droplet discharge method, a functional film is formed by discharging (coating) a liquid functional liquid, drying, and baking. Examples of the droplet discharge method include an inkjet method using an inkjet device.
Therefore, when the functional liquid is applied, the followability to the base shape of the functional film is improved by relaxing the step on the base surface (pixel electrode 109). As a result, the film thickness uniformity of the functional film is improved.

On the other hand, in the pixel region A, it is difficult to eliminate the step generated on the surface of the base layer 30. Therefore, even when the step relief assisting layer 35 is used, it is difficult to completely eliminate the step generated on the surface of the underlayer 30. The inventor has found a condition of the step height and the taper angle that does not affect the film thickness uniformity of the functional layer 10 formed in the upper layer in the underlayer 30. When this condition is satisfied, the followability to the base shape of the functional film applied by the droplet discharge method is increased, and thus it has been found that the functional layer 10 having high film thickness uniformity can be formed.
In this embodiment, the followability of the functional film (formation material of the functional layer 10) applied to the surface is high, and the state of the base on which the functional layer 10 having a uniform film thickness can be formed is referred to as the high flatness state.

Here, the allowable range of the step height and the taper angle in the underlayer 30 will be described.
FIG. 4A is a graph showing the relationship between the height of the step and the taper angle in the underlayer 30, and FIG. 4B is a diagram for explaining the graph of FIG. 4A and 4B, X represents the distance when the step height changes from the maximum value to the minimum value, Y represents the step height, and θ represents the taper angle.

  The present inventors reduce the step height to 50 nm shown in FIGS. 4A and 4B by covering the structure with a thickness of about 500 nm (for example, the wirings 101 to 103) with the base layer 30. I confirmed that I can do it. The step height can be obtained by measuring the surface shape with a stylus type step meter, for example.

Here, whether or not the thickness of the functional layer 10 varies (that is, whether or not the flatness of the underlayer 30 is high) is determined not only by the height of the step, but also in FIGS. 4A and 4B. The indicated distance X is also related. That is, even if the height of the step is 50 nm, if the distance X is short, the side surface of the step will rise sharply (a shape with a large taper angle θ). The taper angle θ can be calculated based on the height obtained by scanning the needle with a stylus type step gauge as described above.
On the other hand, the present inventor has confirmed that if the distance X is larger than 90 nm, the taper angle θ is smaller than 30 °, and the side surface of the step can be made sufficiently smooth.
That is, it was confirmed that if the taper angle θ is smaller than 30 °, followability of the ink (ink that is a constituent material of the functional layer 10) with respect to the ground can be obtained (thickness uniformity of the functional layer 10 can be obtained). . That is, it was found that ink followability (flatness of the underlayer 30) cannot be obtained at a taper angle θ of 30 ° or more.

  Based on the above knowledge, in this embodiment, the step height (height difference) generated in the base layer 30 in the opening 40 of the pixel region A is set to a predetermined value or less (50 nm or less), and the taper angle due to the step is set to a predetermined value. The thickness or the installation location of the step relief assisting layer 35 is set so as to be less than the angle (30 ° or less). Thereby, the film thickness variation of the functional layer 10 formed on the underlayer 30 by using the droplet discharge method is reduced.

The underlayer 30 has a laminated structure including a gate insulating film 16, a first interlayer insulating film 31, and a second interlayer insulating film 32. The gate insulating film 16 is made of an inorganic insulating material such as SiO ₂ or TiO ₂ . The 1st interlayer insulation film 31 and the 2nd interlayer insulation film 32 are comprised from the organic material which has heat resistance and insulation, such as an acrylic resin and a polyimide resin, for example.

  The first interlayer insulating film 31 is provided on the first layer metals 11A1 and 11A2. As described above, the first layer metal 11A2 is disposed above the first layer metal 11A1 in order to form the storage capacitor 107. For this reason, the first layer metals 11A1 and 11A2 are in a state in which the heights of the upper surfaces thereof are different.

  In the present embodiment, the step relief assisting layer 35 includes a first step relief assisting layer 35A and a second step relief assisting layer 35B. The first step relief assisting layer 35A is disposed between the first layer metals 11A1 and 11A2. The first step relief auxiliary layer 35 </ b> A is covered with the first interlayer insulating film 31.

  The first step relief auxiliary layer 35A fills and smoothes the step created between the first layer metals 11A1 and 11A2. As a result, the first interlayer insulating film 31 has a reduced level difference between the first layer metals 11A1 and 11A2.

In the present embodiment, the first step relief auxiliary layer 35A is formed of a metal material (for example, Al, Ag, or the like) that is the same material as the first layer metals 11A1 and 11A2. That is, the first step relief auxiliary layer 35A corresponds to a “first relief layer” in the claims. The first step relief auxiliary layer 35A can be formed in the same process as the patterning process for forming the first layer metals 11A1 and 11A2. Therefore, since it is not necessary to change the photolithography process in order to form the first step relief assisting layer 35A, it can be formed by a simple process.
The first step relief assisting layer 35A may be formed in a configuration different from the patterning process for forming the first layer metals 11A1 and 11A2. In this case, since the degree of freedom of film thickness control is improved, the first step relief assisting layer 35A can be easily made thicker or thinner than the first layer metals 11A1 and 11A2.

  On the first interlayer insulating film 31, the second layer metals 11B1 and 11B2, the source electrode 14, and the drain electrode 15 are arranged. The second layer metals 11B1 and 11B2 include the components of the drive element unit 11 (for example, part of the wirings 101 to 103). The second layer metal 11B1 is disposed on the first layer metal 11A1 via the first interlayer insulating film 31.

  The second layer metal 11B2 is arranged on the first step relaxation assisting layer 35A via the first interlayer insulating film 31. In the present embodiment, since the first step relief assisting layer 35A is formed, the heights of the upper surfaces of the second layer metals 11B2 and 11B1 substantially coincide with each other.

  In the present embodiment, the second step relaxation assisting layer 35B is disposed on the first layer metal 11A2 via the first interlayer insulating film 31. In the second step relief auxiliary layer 35B, the height of the opening end portion of the pixel region A is made higher than the height of the central portion. Note that the difference in height between the opening end and the center of the pixel region A is 50 nm or less. In the present embodiment, the step height refers to the height from the reference plane (the surface of the substrate 100) to the surface of the foundation layer 30.

  The second interlayer insulating film 32 is provided on the second layer metals 11B1 and 11B2. As described above, since the heights of the upper surfaces of the second layer metals 11B1 and 11B2 are substantially the same, the upper surface of the second interlayer insulating film 32 is a substantially flat surface.

In the present embodiment, the second step relief auxiliary layer 35B is formed of a metal material (for example, Al, Ag, or the like) that is the same material as the second layer metals 11B1 and 11B2. That is, the second step relief assisting layer 35B corresponds to a “first relief layer” in the claims. The second step relief auxiliary layer 35B can be formed in the same process as the patterning process for forming the second layer metals 11B1 and 11B2. Therefore, since it is not necessary to change the photolithography process in order to form the first step relief assisting layer 35A, it can be formed by a simple process.
Note that the second level difference relaxation assisting layer 35B may be formed in a configuration different from the patterning process for forming the second layer metals 11B1 and 11B2. In this case, since the degree of freedom in controlling the film thickness is improved, the second step relief assisting layer 35B can be easily made thicker or thinner than the second layer metals 11B1 and 11B2.

  The functional element unit 12 constitutes an organic EL element unit by sequentially laminating the above-described pixel electrode 109, functional layer 10, and counter electrode 110 on the surface of the base layer 30. The pixel electrode 109 is formed in a rectangular shape using a transparent electrode material such as ITO (Indium Tin Oxide) as an anode electrode.

  The pixel electrode 109 is electrically connected to the drain electrode 15 through a contact portion 21 formed in the base layer 30. The counter electrode 110 is made of a transparent conductive material formed of a low work function metal such as alkali metal or alkaline earth metal, MgAg, LiF, ITO (indium tin oxide) or the like as a cathode electrode. The pixel electrode 109 is provided facing the pixel electrode 109.

  In this embodiment, since a top emission structure is adopted, a light reflecting film (not shown) made of a metal material such as Al is provided below the pixel electrode 109 made of a transparent electrode material such as ITO. . Note that in the case where the pixel electrode 109 is made of a metal material (Al) having light reflection characteristics, the light reflection film can be omitted.

  The functional layer 10 is configured by laminating a plurality of thin films including at least the light emitting layer 9. Specifically, the functional layer 10 of the present embodiment is formed by laminating a plurality of thin films including a hole injection layer (HIL) 7, a hole transport layer (HTL) 8, and a light emitting layer (EML) 9. Yes.

  The hole injection layer 7 and the hole transport layer 8 are formed by using, for example, 3,4-polyethylenedioxythiophene-polystyrene sulfonic acid (PEDOT / PSS) dispersion, that is, 3,4-polystyrene sulfonic acid as a dispersion medium. It is formed by drying and firing a liquid material such as a dispersion obtained by dispersing polyethylene dioxythiophene and further dispersing it in water.

  The light emitting layer 9 is made of a known light emitting material capable of emitting fluorescence or phosphorescence. Here, examples of the material for forming the light emitting layer 9 include (poly) fluorene derivative (PF), (poly) paraphenylene vinylene derivative (PPV), polyphenylene derivative (PP), polyparaphenylene derivative (PPP), and polyvinylcarbazole. Polysilanes such as (PVK), polythiophene derivatives, and polymethylphenylsilane (PMPS) are preferably used. In addition, these polymer materials include polymer materials such as perylene dyes, coumarin dyes, rhodamine dyes, rubrene, perylene, 9,10-diphenylanthracene, tetraphenylbutadiene, Nile red, coumarin 6, and quinacridone. It can also be used by doping a low molecular weight material such as. Further, a phosphorescent material such as Ir (ppy) 3 can also be used.

  In addition, about the light emitting layer 9, when performing a color display, by forming the thin film containing the organic material corresponding to each color light of red (R), green (G), and blue (B) for every pixel area A, Each color can be made different. In addition, a sealing layer and a sealing substrate (not shown) are provided on the substrate 100 so as to cover the surface on which the functional element portion 12 is formed.

The functional element unit 12 includes a partition wall 24 that partitions a region where the functional layer 10 is formed.
The functional layer 10 is formed by drying and baking functional liquids containing different types of functional materials for each thin film disposed inside the opening 40 formed by the partition walls 24.

  As shown in FIG. 3, the partition wall 24 includes an inorganic partition wall 24a and an organic partition wall 24b formed on the inorganic partition wall 24a. The partition wall 24 is formed with an opening (pixel opening) 40 that partitions the pixel electrode 109 for each pixel region A and exposes the upper surface of the pixel electrode 109.

  The organic partition wall 24b has a height of 2 μm, for example, while the inorganic partition wall 24a is formed sufficiently thinner than the organic partition wall 24b. Therefore, the height of the partition wall 24 is substantially determined by the height of the organic partition wall 24b.

The inorganic partition wall 24a is formed of an insulating inorganic material such as SiO ₂ and has a lyophilic property because its surface has been subjected to lyophilic treatment to improve wettability. ing. The organic partition wall 24b is formed of, for example, the same organic material as that of the base layer 30, and has a liquid repellency because the surface thereof is subjected to a liquid repellency process (CF ₄ process).

  The organic partition wall 24 b is formed so as to cover the inorganic partition wall 24 a, and the opening shape thereof is the opening shape of the opening 40 of the entire partition wall 24. In this example, the organic partition wall 24b has a tapered inner surface at the opening.

  In the present embodiment, a liquid material (ink) in which an organic material is dissolved or dispersed is discharged into the opening 40 of the partition wall 24 by using a droplet discharge method, and then dried and baked to thereby functional layer 10. Is forming.

  FIG. 5A is a cross-sectional view of a droplet discharge head 51 provided in a droplet discharge apparatus that discharges droplets by a droplet discharge method. The droplet discharge head 51 is provided with a piezo element 53 adjacent to a liquid chamber 52 that contains a liquid material. The liquid material is supplied to the liquid chamber 52 via a liquid material supply system 55 including a material tank for storing the liquid material. The piezo element 53 is connected to the drive circuit 54, and a voltage is applied to the piezo element 53 via the drive circuit 54 to deform the piezo element 53. As a result, the liquid chamber 52 is deformed to increase the internal pressure, and a liquid droplet is discharged from the nozzle 56. That is, by changing the value of the applied voltage, the distortion amount of the piezo element 53 is controlled and the discharge amount of the liquid material is controlled.

  The droplet discharge head 51 is of a multi-nozzle type in which a large number of nozzles 56 are arranged in a single row (or a plurality of rows) at regular intervals as shown in FIG. 5B. From these nozzles 56, droplets of a functional liquid (liquid material) serving as a material for forming the functional layer 10 are ejected independently.

By the way, the film thickness of the functional layer 10 formed by using the droplet discharge method is easily affected by a step generated in the opening 40. That is, when the flatness of the bottom surface of the opening 40 is low and a step of a predetermined range or more (the above-described step of 50 nm or more) occurs, the liquid material disposed in the opening 40 is dried and fired. The variation in the film thickness of the functional layer 10 becomes large.
As described above, when the film thickness of the functional layer 10 varies, the uniformity of the light emission luminance due to the light emission unevenness in the pixel is lowered.

  On the other hand, in the present embodiment, various wirings and the like constituting the drive element unit 11 are concentrated on the periphery of the opening 40 of the pixel region A, so that the base layer 30 in the central portion of the pixel region A and The flatness of the pixel electrode 109 formed on the base layer 30 is improved.

  When the liquid material is discharged into the opening 40 of the partition wall 24 using the droplet discharge method, the liquid material forms a flat liquid film in the central portion of the pixel region A. Therefore, the functional layer 10 can form a highly flat film in the central portion of the pixel region A.

  In addition, since the base layer 30 covers the drive element unit 11 in the peripheral region of the opening 40 (pixel region A), the flatness of the upper surface of the base layer 30 may be reduced. On the other hand, in the present embodiment, by arranging the step relief auxiliary layer 35 in the base layer 30 in the peripheral region of the opening 40, it is possible to reduce the step generated on the surface of the base layer 30. Therefore, the pixel electrode 109 formed on the base layer 30 has high surface flatness.

  Specifically, a predetermined amount of a dispersion of PEDOT / PSS, which is a material for forming the hole injection layer 7 and the hole transport layer 8, is dropped into the opening 40 by a droplet discharge method using the droplet discharge head 51. This is discharged, and is thereby disposed on the exposed surface of the pixel electrode 109.

  Thereafter, by performing drying treatment and then baking treatment at 200 ° C. for about 10 minutes, the hole injection layer 7 and the hole transport layer 8 constituting a part of the thin film of the functional layer 10 have a thickness of, for example, 20 nm. It is formed to about ~ 100 nm.

  According to this embodiment, since the surface flatness of the pixel electrode 109 is high as described above, the PEDOT / PSS dispersion liquid can form a substantially flat liquid film in the opening 40. Therefore, the hole injection layer 7 and the hole transport layer 8 can form a highly flat film over the entire region including the central portion and the peripheral portion of the pixel region A.

  Next, a light emitting layer 9 is formed on the hole injection layer 7 and the hole transport layer 8. Also in the formation process of the light emitting layer 9, similarly to the formation process of the hole injection layer 7 and the hole transport layer 8, a droplet discharge method which is a droplet discharge method is performed.

  Thereafter, for example, heat treatment is performed at 130 ° C. for about 30 minutes in a nitrogen atmosphere, and the light emitting layer 9 serving as a functional film constituting the functional layer 10 is formed in the opening 40 formed in the partition wall 24, that is, on the pixel region A. Is formed to a thickness of about 50 nm to 200 nm. As the solvent used in the material for forming the light emitting layer 9, a solvent that does not re-dissolve the hole injection layer 7 and the hole transport layer 8, for example, xylene or cyclohexylbenzene is preferably used.

  According to the present embodiment, as described above, since the flat hole injection layer 7 and the hole transport layer 8 are formed by the high surface flatness of the pixel electrode 109, the forming material of the light emitting layer 9 is formed. Can form a substantially flat liquid film in the opening 40. Therefore, the light emitting layer 9 can form a film having high flatness over the entire region including the central portion and the peripheral portion of the pixel region A.

  Next, a transparent conductive material is formed to cover the light emitting layer 9 and the organic partition wall 24b, and the counter electrode 110 is formed. Unlike the formation of the hole injection layer 7, the hole transport layer 8, and the light emitting layer 9, the counter electrode 110 is not formed selectively only in the pixel region A by performing a vacuum deposition method or the like. The counter electrode 110 is formed on almost the entire surface of the substrate 100.

  Thereafter, an adhesive layer (not shown) is formed on the counter electrode 110 using an adhesive, and a sealing substrate (not shown) is further bonded by this adhesive layer to perform sealing. Thereby, the electro-optical device 1 is obtained.

  As described above, according to the present embodiment, in the pixel region A, the display performance is improved by suppressing the film thickness unevenness of the functional layer 10 (the hole injection layer 7, the hole transport layer 8, and the light emitting layer 9). Can be improved.

  Further, in the electro-optical device 1 according to the present embodiment, it is possible to ensure the uniformity of the thickness of each thin film while suppressing the influence due to the height difference of the base layer 30 generated in the pixel region A. As a result, as described above, it is possible to further improve the uniformity of the light emission luminance. Therefore, it is suitable for application to a top emission structure in which light is extracted from the side opposite to the substrate 100.

(Second Embodiment)
Subsequently, a second embodiment of the present invention will be described. FIG. 6 is a cross-sectional view showing a cross-sectional structure of the pixel region A1 of the electro-optical device 1A of the present embodiment. The difference between this embodiment and the said embodiment is the material of a level | step difference mitigation auxiliary | assistant layer, and other than that is common. Therefore, below, the same code | symbol is attached | subjected about the member and structure common to the said embodiment, and the detailed description is abbreviate | omitted.

  As shown in FIG. 6, also in this embodiment, the step difference is eased by disposing the step relief assisting layer 135 in a region where a large step is caused by the drive element portion 11 in the base layer 30.

  In the present embodiment, the level difference relief auxiliary layer 135 includes a first level difference relief auxiliary layer 135A and a second level difference relief auxiliary layer 135B.

  The first step relief auxiliary layer 135A is made of an insulating material that is a different material from the first layer metals 11A1 and 11A2. That is, the first step relief assisting layer 135A corresponds to a “second relief layer” in the claims. The first step relief auxiliary layer 135A can be formed in a separate process from the patterning process for forming the first layer metals 11A1 and 11A2. Therefore, since the degree of freedom in layout is increased, the step generated in the pixel region A can be relaxed satisfactorily. Note that since the first step relief assisting layer 135A has an insulating property, it can be disposed in contact with the other wirings 101 to 103 and the like. Therefore, it can be formed at a desired position in the underlayer 30.

  The first step relief assisting layer 135A may be formed of a metal material (for example, Al, Ag, or the like) that is the same material as the first layer metals 11A1 and 11A2. In this case, the first step relief auxiliary layer 135A corresponds to a “first relief layer” in the claims. According to this, it is not necessary to change the photolithography process in order to form the first step relief assisting layer 135A, and it can be formed by a simple process.

  Further, the second step relief assisting layer 135B is made of an insulating material that is a different material from the second layer metals 11B1 and 11B2. That is, the second step relief assisting layer 135B corresponds to a “second relief layer” in the claims. The second step relief assisting layer 135B can be formed in a separate process from the patterning process for forming the second layer metals 11B1 and 11B2. Therefore, since the degree of freedom in layout is increased, the step generated in the pixel region A can be relaxed satisfactorily. Note that since the second level difference relaxation assisting layer 135B has an insulating property, it can be disposed in contact with the other wirings 101 to 103 and the like. Therefore, it can be formed at a desired position in the underlayer 30.

Incidentally, since an insulating material is disposed between the first layer metal 11A2 and the pixel electrode 109, there is a parasitic capacitance. In the present embodiment, an insulating material having a low dielectric constant is selected as the second step relaxation assisting layer 135B disposed between the first layer metal 11A2 and the pixel electrode 109. For example, the second step relaxation assisting layer 135B may be formed using a material having a low dielectric constant, such as polyimide, instead of SiO ₂ and SiN that are normally used as insulating materials.

  In addition, it is desirable that the second step relief assisting layer 135B has a relatively thick film thickness as compared to the first step relief assisting layer 135A. In this way, the distance between the first layer metal 11A2 and the pixel electrode 109 is increased, so that the parasitic capacitance can be reduced.

  Further, as a method for reducing the parasitic capacitance between the first layer metal 11A2 and the pixel electrode 109, for example, the second step relief assisting layer 135B is not formed in a solid film shape, but shown in FIG. Such dot shapes may be formed in a stripe shape as shown in FIGS. 7B and 7C. The difference between FIG. 7B and FIG. 7C is that the stripe direction differs by 90 degrees.

  According to the second step relaxation assisting layer 135B shown in FIGS. 7A, 7B, and 7C, the insulating material is reduced by the area of the recess 136 as shown in FIG. The capacity can be reduced.

  A second interlayer insulating film 32 is formed between the pixel electrode 109 and the second step relaxation assisting layer 135B. The second interlayer insulating film 32 serves not only as a function of the insulating layer but also as a planarizing layer with respect to the underlying layer when, for example, an organic resin or the like is formed by a coating method (spin coating or slitting). I'm in charge. At that time, as shown in FIGS. 7A, 7B, and 7C, discontinuous pattern arrangement is performed at a constant period by arranging the second step relief assisting layer 135B in a dot shape or a stripe shape. By realizing this, it is possible to obtain an effect that the second interlayer insulating film 32 as an upper layer is further planarized.

  For example, the underlying layer 30 covering the drive element unit 11 has a complicated layout and laminated structure of the first layer metals 11A1, A1 and the second layer metals 11A2, B2 depending on the design of the drive element unit 11. Then, irregularities are likely to occur on the film surface (the surface of the base layer 30) immediately before the second interlayer insulating film 32 is formed. In this case, when the second step relaxation assisting layer 135B is formed in a solid film shape, as shown in FIG. 8B, the second interlayer insulating film 32 on the second step mitigation assisting layer 135B also has a step on the surface. Arise.

  On the other hand, as shown in FIGS. 7A, 7B, and 7C, if the second level difference mitigation auxiliary layer 135B has a discontinuous pattern arrangement at a constant period, the second level difference mitigation auxiliary layer. The upper surface of 135B is hardly affected by the unevenness of the underlayer 30. Therefore, if a material with higher wettability is used as the second step relaxation assisting layer 135B, the film thickness uniformity of the second interlayer insulating film 32 is improved as a result, and as a result, the second interlayer insulating film The film thickness uniformity of the pixel electrode 109 formed on the pixel 32 and the functional layer 10 formed on the pixel electrode 109 can be improved.

  Note that a greater effect can be obtained by setting the period (line and space) of the dot shape and stripe shape shown in FIGS. 7A, 7B, and 7C to a higher period (high definition). In order to obtain the effect of improving the flatness of the second interlayer insulating film 32, it is preferable to select the dot shape rather than the stripe shape.

(Electronics)
Next, specific examples of the electronic apparatus including the electro-optical device 1 will be described with reference to FIGS. 9, 10, and 11.
FIG. 9 is a perspective view showing an example of the mobile phone 200. As shown in FIG. 9, the cellular phone 200 is an example in which the cellular phone main body 201 is provided, and the electro-optical device 1 is used for the display unit 202 provided in the cellular phone main body 201.

  FIG. 10 is a perspective view showing an example of a wrist watch 300. As shown in FIG. 10, the wristwatch 300 includes a timepiece main body 301, and the electro-optical device 1 is used for a display unit 302 provided in the timepiece main body 301.

  FIG. 11 is a perspective view showing an example of a portable information processing apparatus 400 such as a personal computer. As shown in FIG. 11, the portable information processing apparatus 400 includes an apparatus main body 401 and is an example in which the electro-optical device 1 is used for a display unit 402 provided in the apparatus main body 401.

  In addition, as an electronic apparatus including the electro-optical device 1, for example, a digital still camera, a vehicle-mounted monitor, a digital video camera, a viewfinder type or a monitor direct-view type video tape recorder, a car navigation device, An electronic device having a display unit such as a pager, an electronic notebook, a calculator, a workstation, a video phone, or a POS terminal can be given.

In addition, this invention is not necessarily limited to the thing of the said embodiment, A various change can be added in the range which does not deviate from the meaning of this invention.
For example, in the above-described embodiment, the case where the upper surface of the underlayer 30 is flattened by arranging (embedding) the step relief assisting layers 35 and 135 inside the underlayer 30 has been described as an example. 35 and 135 may be provided on the upper surface of the underlayer 30 to reduce the level difference between the upper surface of the underlayer 30, that is, the surface on which the pixel electrode 109 is formed.

  For example, in the above-described embodiment, the partition wall 24 has a two-stage structure including the inorganic partition wall 24a and the organic partition wall 24b. However, the structure is not necessarily limited to such a structure, and a thin film forming a functional film is used. In addition, the structure, arrangement, number, and the like of the stepped portions can be changed as appropriate.

  In the above-described embodiment, an electro-optical device having an organic EL element has been described as an example of an electro-optical device. However, the present invention is not limited to this, and optical characteristics are obtained by an electrical action. The present invention can be widely applied to electro-optical devices in which the angle changes.

  In the above embodiment, the case where a TFT is used as a drive element or a switching element as an active matrix type electro-optical device has been described. However, a TFD (thin film diode) can also be used as the drive element or the switching element. Further, the present invention can be similarly applied to a passive matrix electro-optical device instead of an active matrix electro-optical device.

A, A1... Pixel region, 1, 1A... Electro-optical device, 10... Functional layer, 11... Drive element section, 11 A 1 and 11 A 2. Partition wall 30... Base layer 31. First interlayer insulating film 32. Second interlayer insulating film 33. Contact hole 35 35 135 Step relief auxiliary layer 35 A 135 A First step relief auxiliary layer 35B, 135B ... second level difference relief layer, 100 ... substrate, 108 ... driving TFT (switching element), 109 ... pixel electrode.

Claims (14)

A substrate,
A driving element unit provided on the substrate; a base layer covering the driving element unit;
A partition wall provided on the underlayer;
A plurality of pixel regions defined by the base layer and the partition;
A functional layer disposed in the pixel region and formed by a droplet discharge method;
A step relief assisting layer that is disposed on or within the foundation layer and relaxes a step produced in the pixel region by the drive element portion;
An electro-optical device. The electro-optical device according to claim 1, wherein the base layer has a laminated structure including at least one interlayer film. The drive element unit includes at least one wiring layer,
The electro-optical device according to claim 2, wherein the step relaxation assisting layer includes a first relaxation layer formed of the same material as the wiring layer. The electro-optical device according to claim 2, wherein the step relief assisting layer includes a second relaxation layer formed of a material different from that of the wiring layer. The electro-optical device according to claim 4, wherein the second relaxation layer is formed of an insulating material. In the case where the step relaxation assisting layer includes the first relaxation layer and the second relaxation layer,
The electro-optical device according to claim 5, wherein the second relaxation layer is thicker than the first relaxation layer. The electro-optical device according to claim 5, wherein the second relaxing layer has a dot shape or a stripe shape in plan view. In the case where the step relaxation assisting layer includes the first relaxation layer and the second relaxation layer,
The electro-optic according to any one of claims 5 to 7, wherein the predetermined step is relaxed only by the first relaxing layer, and the first relaxing layer is thicker than the wiring layer. apparatus. In the case where the step relaxation assisting layer includes the first relaxation layer and the second relaxation layer,
The electro-optic according to any one of claims 5 to 7, wherein the predetermined step is relaxed only by the second relaxing layer, and the second relaxing layer is thicker than the wiring layer. apparatus. In the case where the step relaxation assisting layer includes the first relaxation layer and the second relaxation layer,
The level difference is relaxed by the first relaxation layer and the second relaxation layer, and the first relaxation layer is thicker than the wiring layer. The electro-optical device described. In the case where the step relaxation assisting layer includes the first relaxation layer and the second relaxation layer,
The predetermined relaxation step is relaxed by the first relaxation layer and the second relaxation layer, and the second relaxation layer is thicker than the wiring layer. The electro-optical device according to Item. 12. The electro-optical device according to claim 1, wherein a step taper angle of the surface of the base layer is 30 degrees or less over the entire pixel region. The electro-optical device according to claim 1, wherein a height difference generated on a surface of the base layer is 50 nm or less over the entire pixel region.   An electronic apparatus comprising the electro-optical device according to claim 1.

Images