Patent Application
20250022865
The present invention relates to a display device and a method for manufacturing a display device.
A so-called LED display in which a minute LED chip is arranged in a pixel arranged in a matrix has been developed as a next-generation display. An LED is a self-luminous element similar to an OLED, but unlike the OLED, it is composed of an inorganic compound containing gallium (Ga), indium (In), and the like. Therefore, as compared with an OLED display, it is easy to ensure an LED display with high reliability. Furthermore, the LED has high luminous efficacy and high brightness. Therefore, the LED display is expected as a next-generation display with high reliability, high brightness, and high contrast.
In the LED display, individual LED chips need to be separated from a sapphire substrate (also referred to as an element substrate) on which the LED is formed into individual chips, and the individual chips need to be arranged in a pixel of a circuit substrate (also referred to as a backplane, a TFT substrate). An LED display in which an LED chip is arranged in a concave part arranged in a planarization film is disclosed in U.S. Pat. No. 10, 937, 815.
A display device according to an embodiment of the present invention includes a substrate provided on a driving circuit, an adhesive layer covering the substrate, a first LED chip provided on the adhesive layer, a pixel circuit provided on the adhesive layer, separated from the first LED chip, a light shielding layer provided on the adhesive layer, and a first opening of the same shape as that of the first LED chip when viewed in a plan view and a second opening of the same shape as that of the pixel circuit when viewed in a plan view, an insulating layer covering the driving circuit and the pixel circuit, and a first wiring provided on the insulating layer, connected to the first LED chip and the pixel circuit, wherein the first wiring overlaps the light shielding layer.
A method for manufacturing display device includes forming an adhesive layer provided on a substrate with a driving circuit, forming a light shielding layer having a plurality of openings and a liquid repellent surface formed on the adhesive layer, applying a solvent on the adhesive layer within the plurality of openings, arranging a first LED chip in contact with the solvent in a first opening of the plurality of openings, arranging a second LED chip in contact with the solvent in a second opening of the plurality of openings, adhering the adhesive layer to the first LED chip and the pixel circuit to the adhesive layer by evaporating the solvent, forming an insulating layer on the driving circuit, the first LED chip, and the pixel circuit, forming a first contact hole reaching the first LED chip and a second contact hole reaching the pixel circuit in the insulating layer, and forming a first wiring on the insulating layer to connect the first LED chip and the pixel circuit through the first contact hole and the second contact hole.
In U.S. Pat. No. 10,937,815, a wiring connected to an LED chip is routed around a display surface side of an LED display. In this case, the routing wiring connected to the LED chip is reflected by light emitted by the LED chip. As a result, the visibility of the LED display is reduced. In addition, when the positional accuracy for mounting the LED chip on a circuit substrate is improved, the manufacturing tact is deteriorated.
In view of the above, an object of an embodiment of the present invention is to provide a display device that suppresses light emitted from the LED chip from being reflected by a metal wiring and improves visibility of an image. Another object of an embodiment of the present invention is to improve manufacturing tact in alignment for mounting the LED chip on the circuit substrate.
Hereinafter, embodiments of the present invention will be described with reference to the drawings. Each of the embodiments is merely an example, and those of ordinary skill in the art can easily conceive of the present invention by appropriately changing it while keeping the gist of the invention and such changes are naturally included in the scope of the present invention. Furthermore, in order to make the description clearer, the drawings may schematically show the width, thickness, shape, and the like of each part in comparison with an actual embodiment. However, the illustrated shapes are merely examples, and do not limit the interpretation of the present invention.
In the embodiments of the present invention, a direction from a substrate toward an LED chip is referred to as “above”, and the opposite direction is referred to as “below”. However, the expression “on” or “under” merely describes the vertical relationship of each element. For example, the expression that the LED chip is arranged on the substrate includes the case where another member is interposed between the substrate and the LED chip. Furthermore, the terms “on” or “under” include not only the case where the elements overlap in a plan a view, but also the case where they do not overlap.
In describing the embodiments of the present invention, elements having similar functions as elements already described will be denoted by the same reference signs or the same reference signs plus a letter of the alphabet or other symbols, and the description thereof may be omitted. Furthermore, when it is necessary to explain a certain element by distinguishing between the respective colors of RGB, a symbol R, G, or B is attached after the reference sign indicating the element to distinguish the element. However, when the element does not need to be described separately for the respective colors of RGB, the description will be made using only the reference sign indicating the element.
In the present embodiment, a display device 100 according to an embodiment of the present invention will be described with reference to
The column control circuit 107 includes a column driver 108 connected to each column of the pixel 110. The column driver 108 is connected to a data line 136 that supplies a data signal in common to all the pixels 110 arranged in the column. In addition, the row control circuit 105 includes a row driver 106 connected to each row of the pixel 110. The row driver 106 is connected to a select line 134 that supplies a select signal in common to all the pixels 110 arranged in the row. The plurality of arrayed pixels 110 is controlled by the controller 104 via the row control circuit 105 and the column control circuit 107.
The pixel circuit 130 is formed on a substrate separate from the substrate 101. For example, the pixel circuit 130 is a bare chip such as an unpackaged integrated circuit substrate such as a semiconductor substrate.
Although not shown in
An insulating layer 144 and an insulating layer 152 are arranged on the substrate 101. For example, a glass substrate, a plastic substrate, a ceramic substrate, or a metal substrate is used as the substrate 101. For example, silicon oxide, silicon nitride, or the like is used as the insulating layer 144 and the insulating layer 152. The insulating layers 144 and 152 will be described in detail later.
In addition, an adhesive layer 112 is arranged on the insulating layer 152. The adhesive layer 112 is arranged on one surface of the substrate 101. In addition, the adhesive layer 112 covers the display region 102 and the peripheral region 103. The adhesive layer 112 fixes the LED chip 120 arranged in the substrate 101. For example, an adhesive layer with sufficient light transmittance in a visible-light region such as a VPA (vinyl sulfonate)-based adhesive layer, a polyimide-based adhesive layer, an acrylic-based adhesive layer, a silicone-based adhesive layer, a polyester-based adhesive layer, or a rubber-based adhesive layer is used as the adhesive layer 112. For example, a thickness of the adhesive layer 112 is 1 μm or more and 5 μm or less. When the thickness is small, the adhesive strength becomes weak, and when the thickness is large, the cost increases, and moreover, an adhesive stain caused by the adhesive layer tends to occur.
The LED chips 120R, 120G, and 120B and the pixel circuit 130 are arranged on the adhesive layer 112. A micro LED or a mini LED is used as the LED chip 120. The micro LED is an LED having a size of 100 μm or less, and the mini LED is an LED having a size of 100 μm to 200 μm. In the display device 100, any size of LED can be used, and may be appropriately used depending on the size of the pixel 110. For example, in the present embodiment, the LED chip 120 is a micro LED, and has a vertical width of 7 μm to 150 μm, a horizontal width of 3 μm to 100 μm, and a height of about 3 μm to 15 μm. The LED chip 120 is arranged such that terminals 122-1 and 122-2 are arranged on the upper side. For example, the terminals 122-1 and 122-2 are formed of a conductive material such as gold (Au), copper (Cu), silver (Ag), tin (Sn), or aluminum (Al). The same applies to the LED chips 120G and 120B and the pixel circuit 130. The LED chip 120 emits light to the substrate 101 side. Therefore, the substrate 101 side becomes the display surface of the display device 100.
A light-shielding layer 114 is arranged on the adhesive layer 112. The light-shielding layer 114 is a black film with insulating properties. The light-shielding layer 114 is also referred to as a black matrix. The light-shielding layer 114 has a plurality of openings 115. The plurality of openings 115 corresponds to positions where the LED chips 120R, 120G, and 120B and the pixel circuit 130 are arranged, respectively. As shown in
An insulating layer 116 is arranged to cover the light-shielding layer 114, the LED chips 120R, 120G, and 120B, and the pixel circuit 130. The insulating layer 116 is not illustrated in
As shown in
One of the plurality of wirings 118 connects the pixel 110 and the row driver 106. For example, as shown in
For example, a metal such as aluminum or copper is used as the wiring 118. The gate electrode 142, the source/drain electrodes 148-1 and 148-2, wirings for routing the gate electrode 142, and the source/drain electrodes 148-1 and 148-2 are also made of a metal such as aluminum or copper. Such metal wiring reflects the light emitted from the LED chip and reduces the visibility of the image. In addition, contrast is reduced due to the mixing of colors of the light emitted by the LED chip.
In the display device 100 according to an embodiment of the present invention, the light-shielding layer 114 is arranged in a region other than the region where the LED chips 120R, 120G, and 120B and the pixel circuit 130 are arranged. That is, in the display region 102, a gap arranged by the LED chips 120, 120G, 120B, and the pixel circuit 130 is filled with the light-shielding layer 114. In addition, terminals of the LED chip 120 are arranged above. Therefore, the plurality of wirings 118 is routed above the light-shielding layer 114. Therefore, in the display region 102, the wiring arranged below the LED chips 120R, 120G, and 120B can be omitted. In the display device 100, since the display surface is the lower side of the substrate 101, the plurality of wirings 118 routed in the display region 102 can be shielded by the light-shielding layer 114. As a result, the light emitted from the LED chips 120R, 120G, and 120B is suppressed from being reflected by the metal wiring 118, so that it is possible to provide the display device 100 in which the visibility of the image is improved. In addition, since a region where the driving circuit is arranged is spaced apart from the region where the LED chip 120 is arranged, the influence of the light emitted from the LED chip 120 can be reduced.
Next, a method for manufacturing the display device 100 according to an embodiment of the present invention will be described with reference to
As shown in
In a later step, a solvent must be applied to adhere the LED chip 120 and the pixel circuit 130 to the substrate 101. However, if a solvent is applied to the light-shielding layer 114, it is difficult to accurately bond the LED chip 120 and the pixel circuit 130 to the inside of the opening 115. Therefore, it is preferable that the light-shielding layer 114 has liquid repellency. In other words, a surface contact angle of the light-shielding layer 114 is preferably larger than a surface contact angle of the adhesive layer 112 inside the opening 115. For example, the surface contact angle of the light-shielding layer 114 is preferably 85° or more. Since the light-shielding layer 114 has liquid repellency, it becomes easy to apply the solvent to a desired region when applying the solvent later.
The liquid repellency of the light-shielding layer 114 can be enhanced by containing a fluorine-containing compound in a black resin (for example, a cardo resin, a low-molecular-weight acryl resin, or the like) having a high insulating property. The liquid repellency of the light-shielding layer 114 can be adjusted by the content of the fluorine-containing compound. The greater the amount of the fluorine-containing compound, the higher the liquid repellency of the light-shielding layer 114. The fluorine-containing compound is a compound containing a fluorine atom.
For example, in the case where the light-shielding layer 114 is applied by injection, a liquid-repellent component may be added to a black resist. The liquid repellent component refers to a surfactant containing fluorine. The fluorine surfactant is uniformly mixed in liquid form but tends to migrate and segregate to the top layer of the film when applied or dried. Utilizing this property and adding the fluorine surfactant to the black resist, only the liquid repellency of the upper layer of the light-shielding layer 114 can be enhanced when the black resist is applied and dried.
In addition, after the light-shielding layer 114 is formed, a fluororesin may be formed on the light-shielding layer 114 by a so-called lift-off method. For example, a pattern is formed in the opening 115 using a resist. Next, a fluororesin is formed on the light-shielding layer 114 and the pattern using the resist, and then the resist is removed. Therefore, a fluororesin may be formed on the light-shielding layer 114.
In addition, after forming the black resin having insulating properties as the light-shielding layer 114, the surface of the light-shielding layer 114 may be subjected to a plasma treatment using a gas containing fluorine or a fluorine compound (for example, CF4). For example, after a mask is formed on the opening 115, the light-shielding layer 114 is exposed to an atmosphere in which a plasma containing fluorine is formed. A fluorine compound is formed on the light-shielding layer 114. As a result, the liquid repellency of the surface of the light-shielding layer 114 may be higher than that of the surface of the adhesive layer 112 in the opening 115.
As described in
The position of the LED chip 120 arranged on the solvent 117 fluctuates for a while in association with the fluctuation of the solvent 117. After a certain period of time, the shape of the solvent 117 becomes stable, so that the position of the LED chip 120 also converges to a predetermined position. In this case, the opening 115 of the light-shielding layer 114 in which the solvent 117 is arranged is a region where the outline of the LED chip 120 is projected, as described above. Therefore, the position where each LED chip 120 converges is a position that substantially coincides with the opening 115. By forming the solvent 117 in the opening 115 in this manner, the position of the LED chip 120 can be determined spontaneously and accurately using the surface tension of the solvent 117.
By positioning the LED chip 120 and the pixel circuit 130 as described above, it is possible to suppress a positional deviation when the LED chip 120 or the pixel circuit 130 is mounted on the substrate 101. As a result, the positional accuracy of the LED chip 120R, the LED chip 120G, the LED chip 120B, and the pixel circuit 130 can be improved.
Finally, the wiring 118 is formed on the insulating layer 116. For example, a metal such as aluminum or copper is used as the wiring 118. A conductive film is formed on the insulating layer 116 and is appropriately patterned to form the wiring 118. As a result, the LED chip 120 and the pixel circuit 130 can be connected. In addition, the pixel circuit 130 and the driving circuit may be connected.
Through the above steps, the display device 100 according to an embodiment of the present invention can be manufactured.
In the present embodiment, although the case where the contact holes for exposing the source/drain electrode 148-2 are formed in the insulating layer 116, the light-shielding layer 114, and the adhesive layer 112 in the peripheral region 103 has been described in the step shown in
In the method for manufacturing the display device 100 according to an embodiment of the present invention, the solvent 117 applied to the surface of the light shielding layer is repelled by imparting liquid repellency to the surface of the light shielding layer. As a result, the solvent 117 can be accurately arranged in the opening of the light shielding layer. After the LED chip 120 and the pixel circuit 130 are arranged on the solvent 117, the position of the LED chip and the pixel circuit is converged to a predetermined position as the form of the solvent 117 is stabilized. As a result, positioning of the LED chip 120 and the pixel circuit 130 can be accurately performed in a short time. As described above, in the method for manufacturing the display device 100, the manufacturing tact in the alignment for mounting the LED chip and the pixel circuit on the substrate can be improved.
In addition, although an example in which a circuit configured by the transistor 150 is used as the row driver 106 or the column driver 108 is described in the present embodiment, an embodiment of the present invention is not limited to this. For example, a bare chip 140 such as an unpackaged integrated circuit substrate such as a semiconductor substrate may be used as the row driver 106 and the column driver 108.
In the case where the bare chip 140 is used for each of the row driver 106 and the column driver 108, there is no need to form a transistor in the substrate 101. Furthermore, in the case where the bare chip is used for each of the row driver 106 and the column driver 108, the insulating layer 144 and the insulating layer 152 may be omitted as appropriate, and the adhesive layer 112 may be formed on the substrate 101. When forming the plurality of openings 115R, 115G, 115B, and 115C in the light-shielding layer 114, the opening 115D for arranging the bare chip 140 may be formed. Since the subsequent steps can be performed in the same manner as the manufacturing steps of the display region 102 described with reference to
Although it has been described that the height of the LED chip 120R, the height of the LED chip 120G, and the height of the LED chip 120B are generally the same, an embodiment of the present invention is not limited to this. The height of the LED chip 120R, the height of the 120G of LED chip, and the height of the ELD chip 120B may be different for each color. The heights of the LED chips 120R, 120G, and 120B may vary from 8 μm to 12 μm due to structural differences and the like. Since the heights of the LED chips 120R, 120G, 120B are different from each other, the connecting surface between the terminals 122-1 and 122-2 and the wiring 118 is not uniform. In addition, the depths of the contact holes formed in the insulating layer 116 are different between the terminal of the LED chip 120 having a smaller height and the terminal of the LED chip 120 having a larger height. Therefore, it is difficult to form a contact hole corresponding to the height of the LED chip 120 in the insulating layer 116, or the wiring may be broken when the wiring 118 is formed.
Therefore, in the case where the heights of the LED chips 120R, 120G, and 120B are different for each color, it is preferable to adjust the thickness of the adhesive layer 112 to make the connecting surface between the terminals 122-1 and 122-2 and the wiring 118 uniform.
In the present embodiment, as shown in
As described above, in the present embodiment, the height increases in the order of the LED chips 120B, 120R, and 120G. Therefore, the thickness of the adhesive layer 112 is adjusted so that the thickness of the adhesive layer 112 increases in the order of the thickness t2, the thickness t1, and the thickness t3. In addition, depending on the height of the LED chip 120G, the thickness t2 and the thickness t4 may be the same size, or the thickness t2 may be greater than the thickness t4. Although
A method for manufacturing the display device 100A shown in
The step of forming the transistor 150 and the insulating layer 152 on the substrate 101 is similar to the step shown in
In the present embodiment, in order to adjust the thickness of the adhesive layer 112 inside the openings 115R, 115G, 115B, and 115C, for example, a photoresist with adhesive properties is used as the adhesive layer 112. For example, the above-described VPA (vinyl sulfonate)-based adhesive layer may be used as the photoresist with adhesive properties.
First, similar to the step shown in
For example, in a method of forming the adhesive layer 112 having a different thickness, an adhesive layer is formed in each of the regions 113a, 113b, and 113c with a predetermined thickness, and then an adhesive layer is formed in each of the regions 113b and 113c with a predetermined thickness, and finally, an adhesive layer is formed in the region 113c with a predetermined thickness. As a result, the adhesive layer 112 in which the adhesive layers 112a, 112b, and 112c are arranged can be formed.
Since the steps of arranging the LED chip 120 and the pixel circuit 130 on the adhesive layer 112 are similar to the descriptions in
Through the above steps, the display device 100A according to an embodiment of the present invention shown in
According to the display device 100A of the present embodiment, even when the height of the LED chip 120R, the height of LED chip 120G, and the height of LED chip 120B are different for each color, the connecting surface between the terminals 122-1 and 122-2 and the wiring 118 can be made uniform. As a result, the depth of the contact hole formed in the insulating layer 116 can be made substantially the same regardless of the height of the LED chip 120. Therefore, it is easy to form the contact hole in the insulating layer 116, and it is possible to suppress the wiring from breaking when forming the wiring 118.
Each of the embodiments described above as an embodiment of the present invention can be appropriately combined and implemented as long as no contradiction is caused. Furthermore, the addition, deletion, or design change of components, or the addition, deletion, or condition change of processes as appropriate by those skilled in the art based on the display device of each embodiment are also included in the scope of the present invention as long as they are provided with the gist of the present invention.
Furthermore, it is understood that, even if the effect is different from those provided by each of the above-described embodiments, the effect obvious from the description in the specification or easily predicted by persons ordinarily skilled in the art is apparently derived from the present invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2022-054243 | Mar 2022 | JP | national |
This application is a Continuation of International Patent Application No. PCT/JP2023/009301, filed on Mar. 10, 2023, which claims the benefit of priority to Japanese Patent Application No. 2022-054243, filed on Mar. 29, 2022, the entire contents of each are incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/JP2023/009301 | Mar 2023 | WO |
| Child | 18896908 | US |
