JP2007059559A - Mounting method, manufacturing method for electronic device, and display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a novel mounting method for mounting an electronic element in a given place. <P>SOLUTION: The mounting method includes a step of placing a droplet 20 including a dispersion medium 21 and a single element chip 22 in the dispersion medium 21 on one main surface of a board 10, and a step of placing the element chip 22 on the board 10 by eliminating the dispersion medium 21 from the droplet 20. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a mounting method, an electronic device manufacturing method, and a display device.

  An active liquid crystal display device and an organic electroluminescence display element are formed on a glass substrate, and pixels arranged in a matrix on the substrate are controlled by transistor elements arranged in the vicinity thereof. In the current technology, since a transistor of a crystalline semiconductor cannot be formed on a glass substrate, a thin film transistor made of amorphous silicon or a polysilicon thin film is used for pixel control. A thin film transistor has an advantage that it can be manufactured on a large-area substrate at low cost, but has a problem that it has a lower mobility than a crystalline silicon and cannot operate at high speed. In order to solve this problem, there has conventionally been proposed a method in which a number of transistors are manufactured in advance on a silicon wafer and then cut out from the wafer and placed on a substrate.

  For example, a method has been proposed in which a transistor is placed in a hole by making a hole in the substrate in advance and exposing the substrate to a liquid in which a single crystal transistor is dispersed (Patent Document 1 and Non-Patent Document 1). Patent Document 1). By making the shape of the hole and the shape of the transistor the same, a transistor oriented in a predetermined direction is disposed at a predetermined position on the substrate. It is described that 10,000 transistors having a size of 10 to several hundred μm can be arranged on a 3 inch square substrate by this method.

A method for manufacturing a liquid crystal display element in which a large number of single crystal transistor elements are arranged on a glass substrate is also disclosed (see Patent Document 2). In this method, a rubber-based polymer thin film having a hole for accommodating a single crystal silicon transistor element is formed on a glass substrate, and the glass substrate is exposed to a liquid in which the single crystal silicon transistor element is dispersed, thereby forming a single crystal. A transistor element is disposed on a glass substrate. In order to make a hole in a glass substrate, it was necessary to use an expensive device such as a laser processing device. However, if this method is used, it is not necessary to make a hole directly in the substrate, so that elements can be arranged with a simple device. There is an advantage.
US Pat. No. 6,417,025 Japanese Patent Laid-Open No. 2003-5212 Information Display (Information Display), p12-16, 1999

  In a conventional method in which a substrate is exposed to a liquid in which a plurality of transistor elements are dispersed and the element is inserted into a hole in the substrate, an element approaching the vicinity of the hole does not enter the hole with a probability of 100%. For this reason, the number of elements in the dispersion must be larger than the number to be arranged on the substrate. Therefore, in order to produce one display device, it is necessary to produce more transistors than necessary in advance, and there is a problem that the manufacturing cost increases. In addition, since whether or not an element enters a hole is governed by the probability, even if the substrate is exposed to the dispersion solution for a long time, the probability that there is a hole without an element does not become zero. For this reason, it is necessary to inspect whether or not the elements are arranged in all the holes, and there is a problem that the number of manufacturing steps increases.

  In the conventional method, it is difficult to arrange two or more types of elements at positions where they should be arranged.

  Under such circumstances, one of the objects of the present invention is to provide a novel mounting method for mounting an electronic device at a predetermined position. Another object of the present invention is to provide a method of manufacturing an electronic device using the mounting method and an electronic device manufactured by the method.

  In order to achieve the above object, a mounting method of the present invention is a mounting method for mounting an element chip containing an electronic device on a substrate, and (i) a dispersion medium and only one of the dispersion medium and the dispersion medium. Placing the droplet (A) containing the element chip on one main surface of the substrate; and (ii) removing the dispersion medium from the droplet (A), thereby Placing on the substrate.

  The method of the present invention for manufacturing an electronic device is a method of manufacturing an electronic device including a substrate and an element chip that includes the electronic device and is mounted on the substrate. Including a step of mounting the element chip.

  Moreover, the display device of the present invention is a display device manufactured using the method for manufacturing an electronic device.

  Another display device of the present invention is a display device including a substrate, a plurality of transistor chips mounted on the substrate, and first and second wirings for controlling the transistor chip. The transistor chip includes an electrode terminal formed on only one main surface thereof, the first wiring is disposed between the substrate and the transistor chip, and the second wiring is connected to the transistor chip. The transistor chip is disposed on the opposite side of the substrate, and each of the plurality of transistor chips is electrically connected to one of the first wiring and the second wiring through the electrode terminal. Has been.

  According to the present invention, it is possible to reliably mount an element chip at a predetermined position. Therefore, unlike the conventional method, the method of the present invention does not require an excessive number of element chips. Further, according to the method of the present invention, it is possible to simplify or omit the step of inspecting whether or not an element chip is mounted. Moreover, according to the method of the present invention, unlike the conventional method, it is possible to eliminate the step of forming a hole in which the element chip is disposed in the substrate. Further, according to the present invention, it is possible to mount a plurality of types of element chips having the same shape or different shapes at respective predetermined locations. By using the method of the present invention, an object of 1 mm or less can be arranged at a predetermined position on the substrate. For example, the method of the present invention can be applied to a method of mounting an IC tag at a predetermined position.

  Embodiments of the present invention will be described below. In the drawings used in the following description, hatching may be omitted for easy viewing. Moreover, in the following description, the same code | symbol may be attached | subjected to the same part and the overlapping description may be abbreviate | omitted.

<Mounting method>
The mounting method of the present invention is a mounting method for mounting an element chip containing an electronic element on a substrate. This method includes a step (i) in which a droplet (A) including a dispersion medium and only one element chip placed in the dispersion medium is disposed on one main surface of the substrate. This method further includes the step (ii) of disposing the element chip on the substrate by removing the dispersion medium from the droplet (A). The method for removing the dispersion medium is not limited. For example, the dispersion medium may be removed by natural drying, or may be removed by heating and / or reduced pressure.

  In this method, it is possible to reliably mount the element chip at a desired position by disposing the droplet (A) containing only one element chip in the portion where the element chip is to be mounted. A plurality of element chips can be mounted using this mounting method. For example, a plurality of element chips (for example, field effect transistors) used for driving the display device can be mounted. In addition, it is possible to repair an electronic device using this mounting method. For example, if there is a defective element chip among a plurality of element chips mounted on an electronic device, the defective element chip is removed, and instead a normal element chip is mounted by the mounting method of the present invention. May be. In addition, after mounting a plurality of element chips by another method, the element chips may be selectively mounted at a location where the element chip could not be mounted using the mounting method of the present invention.

  The substrate on which the element chip is mounted is not limited, and examples thereof include a glass substrate, a metal substrate, a ceramic substrate, and a resin substrate.

  It is preferable that the solvent is removed from the droplet (A) arranged at a predetermined position on one main surface of the substrate without spreading from the predetermined position. Two typical methods for preventing the droplet (A) from spreading on the substrate are listed below.

  In the first method, a first region and a second region surrounded by the first region and having higher wettability of the dispersion medium than the first region exist on one main surface of the substrate. . In this case, in step (i), the droplet (A) is disposed in the second region. According to this configuration, the droplet (A) arranged in the second region is unlikely to spread in the first region. The first region preferably has low wettability of the dispersion medium. In order to keep the droplet (A) in the second region, the surface energy of the first region is preferably 5 dyne / cm or more and less than 40 dyne / cm (preferably in the range of 5 to 25 dyne / cm). The surface energy of the region 2 is preferably 40 dyne / cm or more (preferably in the range of 60 to 1000 dyne / cm).

  An organic film in which the wettability of the dispersion medium of the droplet (A) is lower than that in the second region may be formed in at least a part of the first region. According to this configuration, it is easy to form the first and second regions.

  In the second method, a first region and a second region that is surrounded by the first region and protrudes from the first region exist on one main surface of the substrate. In this case, the droplet (A) is disposed in the second region in the step (i). The upper surface of the protrusion protruding from the substrate is the second region, and the droplet (A) arranged in the second region is difficult to spread from the second region.

  The element chip has a rectangular parallelepiped shape including two surfaces (P1), two surfaces (P2) having an area equal to or larger than the surface (P1), and two surfaces (P3) having an area larger than the surface (P2). The shape may also be In this case, it is preferable that the shape of the surface (P3) and the shape of the second region in which the droplet (A) is disposed are as similar as possible, and more preferably substantially the same. Here, the shape when the vertical and horizontal lengths of the surface (P3) are each 0.8 times (area ratio 0.64 times) is the shape P3x, and the vertical and horizontal lengths are each 1.2 times. The shape when the area ratio is 1.44 times is P3y. “The shape of the surface (P3) and the shape 12s of the second region in which the droplet (A) is disposed are substantially equal” is, for example, a shape in which the shape P3x is included in the shape 12s. It means that the shape 12s is a shape included in the shape 12y.

  In step (ii), one of the two surfaces (P3) is disposed so as to face the one main surface of the substrate. The area of the surface (P3) is preferably at least twice as large as the area of the surface (P2), for example, in the range of 3 to 50 times.

  The surface (P3) may have a rectangular shape. When the shape of the surface (P3) and the shape of the second region are substantially equal and they are rectangular, the element chips can be mounted with their directions aligned. As a result, the connection between the wiring and the electrode terminal of the element chip is facilitated. The long side of the rectangle is preferably about 1.5 to 50 times the short side, for example in the range of 2 to 10 times.

  Note that by devising the arrangement of the electrode terminals of the element chip, it is possible to reliably connect the electrode terminals and the wiring even if the planar shape of the element chip is not rectangular. For example, when a plurality of electrodes are arranged at different distances from the center of the element chip (for example, when electrodes are arranged concentrically), the planar shape of the element chip may be a square or a circle.

  An electrode is formed in the second region, and an electrode terminal may be formed on one of the two surfaces (P3). According to this configuration, when the surface on which the electrode terminal is formed in step (ii) faces the substrate side, the electrode terminal and the electrode can be automatically brought into contact with each other.

  The mounting method of the present invention may further include, after the step (ii), a step of forming an electrode that passes over a surface of the two surfaces (P3) far from the substrate. According to this configuration, the electrode can be connected to the electrode terminal when the surface on which the electrode terminal is formed in the step (ii) faces away from the substrate.

  Three examples will be described below as examples of the method for forming the droplet (A).

  In the first example, the mounting method of the present invention includes, before step (i), (a) placing at least one element chip on one surface where the wettability of the dispersion medium is low, and (b ) Taking one element chip arranged on the surface into the droplet (B) of the dispersion medium (dispersion medium of the droplet (A)) to form the droplet (A). This method is performed, for example, by forming a droplet (B) of a dispersion medium at the tip of a capillary and taking one element chip into the droplet (B). The surface having low wettability of the dispersion medium is, for example, a surface having a surface energy of 5 to 25 dyne / cm.

  In the second example, the dispersion medium of the droplet (A) has conductivity. Then, the step (i) includes a step of forming a droplet (A) from a liquid including a dispersion medium and a plurality of element chips dispersed in the dispersion medium using an electrowetting phenomenon.

  In the mounting method of the present invention, it is preferable that the dispersion medium of the droplet (A) has a property of taking the element chip into the inside. For example, the static contact angle of the dispersion medium with respect to the surface of the element chip may be less than 90 °. Here, the static contact angle means a contact angle of a droplet when the droplet is gently arranged on a horizontal surface. Further, the surface energy of the electronic element may be 40 dyne / cm or more, and the surface tension of the dispersion medium may be 20 dyne / cm or more (for example, 20 to 80 dyne / cm). The preferred dispersion medium varies depending on the material of the substrate and the element chip. As the dispersion medium, for example, water, an organic solvent, or a mixed liquid of water and an organic solvent can be used. An electrolyte may be dissolved in these dispersion media. Specific examples of the dispersion medium will be described later.

  In the mounting method of the present invention, the element chip substrate may be made of single crystal silicon. In this case, the mounting method of the present invention may include a step of forming an element chip by cutting a single crystal silicon substrate after forming a plurality of electronic devices on the single crystal silicon substrate before the step (i). Good. When the element chip is a chip including only one electronic element, the silicon substrate is cut for each electronic element. In this method, after the electronic element is formed, the substrate may be thinned by polishing the back side of the single crystal silicon substrate. The single crystal silicon substrate can be cut by a general method, for example, using a dicer.

  In the mounting method of the present invention, the electronic element may be a transistor (for example, a field effect transistor). Field effect transistors are important as driving elements for display devices. However, the electronic element contained in the element chip is not limited to the transistor, and may be a resistor, a capacitor, or an inductor. There may be one or more electronic elements included in the element chip. The element chip may include a circuit composed of a plurality of electronic elements. The electronic element included in the element chip may be a single crystal silicon transistor or a circuit element in which single crystal silicon transistors are integrated. The longest side of the element chip is, for example, 1000 μm or less.

  When the electronic element of the element chip is a field effect transistor, an electrode pattern is previously formed on the substrate on which the element chip is mounted so as to correspond to the source electrode, the drain electrode, and the gate electrode of the transistor chip. It is sufficient to arrange a droplet containing only one droplet. Such a transistor can be used as a pixel control transistor in an active matrix display device.

<Method for manufacturing electronic device>
The method of the present invention for manufacturing an electronic device is a method for manufacturing an electronic device including a substrate and an element chip including the electronic device and mounted on the substrate. This manufacturing method includes a step of mounting an element chip by the mounting method of the present invention.

  There is no limitation in particular in the electronic device manufactured with this manufacturing method, A display apparatus may be sufficient. Examples of the display device include a liquid crystal display, an organic electroluminescence display, a plasma display, a display using an electrophoretic phenomenon, a display using a magnetic powder, and the like. Examples of other electronic devices manufactured by the manufacturing method of the present invention include a mounting circuit and an IC tag with an antenna. A display device manufactured by this manufacturing method is one of the display devices of the present invention.

<Display device>
The display device of the present invention includes a substrate, a plurality of transistor chips mounted on the substrate, and first and second wirings for controlling the transistor chips. The transistor chip includes electrode terminals formed only on one main surface thereof. The first wiring is disposed between the substrate and the transistor chip. The second wiring is disposed on the opposite side of the substrate from the transistor chip. Each of the plurality of transistor chips is electrically connected to one of the first wiring and the second wiring through an electrode terminal. This display device can be manufactured by the manufacturing method of the present invention.

  Examples of the display device of the present invention include a liquid crystal display, an organic electroluminescence display, a plasma display, a display using an electrophoretic phenomenon, a display using a magnetic powder, and the like.

<Example of mounting method>
An example of the mounting method of the present invention is schematically shown in FIG. First, as shown in FIG. 1A, a substrate 10 having a first region 11 and a second region 12 on one main surface 10s is prepared. The region 12 is surrounded by the region 11. The region 11 is a region where the wettability of the dispersion medium 21 is lower than that of the region 12. The region 12 has a rectangular shape, and electrodes 13 are formed on the two long sides of the rectangle.

  Next, as shown in FIG. 1B, a predetermined volume of the droplet 20 including the dispersion medium 21 and only one element chip 22 is disposed in the second region 12 of the substrate 10. The element chip 22 has a rectangular parallelepiped shape, and the shape of the two principal surfaces (P3) having the largest area is almost the same as the shape of the region 12. Of the two main surfaces (P3) of the element chip, electrode terminals (not shown) are formed on the two long sides of one main surface.

  The region 11 is a region where the dispersion medium 21 has low wettability, and the region 12 is a region where the dispersion medium 21 has high wettability. Therefore, the shape of the contact surface between the droplet 20 arranged in the region 12 and the substrate 10 is the same as the shape of the region 12.

  Next, the dispersion medium 21 is removed from the droplet 20. When the dispersion medium 21 is removed, the element chip 22 is accurately arranged in the second region 12 as shown in FIG. At this time, one main surface (P3) of the element chip 22 is disposed so as to face the substrate 10. When an electrode terminal is formed on the main surface (P3) facing the substrate 10, the electrode terminal is connected to the electrode 13 on the substrate 10. On the other hand, when the electrode terminal is formed on the main surface (P3) far from the substrate, the electrode 13 on the substrate 10 and the electrode terminal of the element chip 22 are not connected. In this case, an electrode passing over the main surface (P3) far from the substrate is formed, and the electrode and the electrode terminal are connected.

  In this way, the element chip 22 is mounted on the substrate 10. A method for producing the droplet 20 including only one element chip 22 and a method for accurately arranging the droplet 20 on the region 12 of the substrate 10 will be described later.

  The principle that the element chip 22 is accurately arranged at a predetermined position of the substrate 10 by evaporation of the dispersion medium 21 will be described with reference to FIGS. 2A to 2D are diagrams schematically showing a cross section passing through the line II-II in FIG. 1B and perpendicular to the substrate.

  When the droplet 20 is arranged on the substrate 10, the droplet 20 stays in the region 12 of the substrate 10 and does not spread to the region 11 as shown in FIG. When the dispersion medium 21 of the droplet 20 evaporates, the droplet 20 becomes small while remaining in the region 12. As a result, the element chip 22 may protrude from the dispersion medium 21 as shown in FIG. A surface tension F21 acts on the element chip 22 protruding from the dispersion medium 21 as shown in FIG. The total force F22 of the surface tension F21 is a force for pulling the element chip 22 back into the dispersion medium 21. In this way, the dispersion medium 21 decreases while the element chip 22 is pulled back into the dispersion medium 21. As a result, the element chip 22 is disposed in the region 12 as shown in FIGS.

  3A to 3C are plan views of the process of FIG. 2 as viewed from above the substrate 10. In FIG. 3, the region 12 is where the dispersion medium 21 exists. Even if the element chip 22 protrudes from the dispersion medium 21, a surface tension F21 that pulls the protruding element chip 22 back into the dispersion medium 21 acts on the element chip 22, so that the element chip 22 remains in the dispersion medium 21. As the dispersion medium 21 decreases, the element chip 22 is accurately arranged in the region 12.

  In order to arrange the element chip 22 as shown in FIG. 2 and FIG. 3, when the element chip 22 protrudes from the dispersion medium 21, surface tension must act in a direction to pull it back into the dispersion medium 21. . 4A and 4B are diagrams showing surface tension acting on the element chip 22 when part of the element chip 22 protrudes from the dispersion medium 21. FIG. The direction of the surface tension acting on the element chip 22 is affected by the contact angle θ of the dispersion medium 21 with respect to the surface of the element chip 22.

  FIG. 4A shows a case where the contact angle of the dispersion medium 21 with respect to the surface of the element chip 22 is less than 90 °. In this case, the surface tension F 21 that is to be pulled back into the dispersion medium 21 acts on the element chip 22 that protrudes from the dispersion medium 21. On the other hand, FIG. 4B shows a case where the contact angle of the dispersion medium 21 with respect to the surface of the element chip 22 is larger than 90 °. In this case, a surface tension F 21 that is pushed out of the dispersion medium 21 acts on the element chip 22 that protrudes from the dispersion medium 21. Therefore, the static contact angle of the dispersion medium 21 with respect to the surface of the element chip 22 is preferably less than 90 °, and more preferably 80 ° or less.

  The smaller the static contact angle of the dispersion medium 21 with respect to the surface of the element chip 22 is, and the greater the surface tension of the dispersion medium 21 is, the greater the force to pull the element chip 22 back into the dispersion medium 21 is. The inventors have found that the element chip 22 is efficiently arranged in the region 12 when the surface tension of the dispersion medium is 20 dyne / cm or more and the surface energy of the element chip 22 is 40 dyne / cm or more. It was.

  Thus, in order to accurately arrange the element chip 22 at a predetermined position on the substrate, it is important to appropriately select the type of the dispersion medium 21 and the surface energy of the element chip 22.

  Examples of the dispersion medium 21 include water, an organic solvent, or a mixed liquid of water and an organic solvent. An electrolyte may be dissolved in these dispersion media. Examples of the organic solvent include ethanol, propanol, butanol, pentanol, hexanol, pentanol, octanol, nonanol, decanol, ethylene glycol, glycerol and other alcohols, ethylene glycol monomethyl ether, ethylene glycol ethyl ether, ethylene glycol monobutyl ether, and other ethers, Ketones such as methyl ethyl ketone, hexane, octane, nonane, decane, undecane, dodecane, tridecane, alkanes such as tetradecane, pentadecane, and hexadecane, tetrahydrofuran, chloroform, and the like can be used. Examples of the mixed solution of water and an organic solvent include a mixed solution of water and alcohol, a mixed solution of water and tetrahydrofuran, and the like.

  When the surface energy of the element chip 22 is less than 40 dyne / cm, it is preferable to treat the surface of the element chip 22 to increase its surface energy. When silicon is present on the surface of the element chip 22, the surface energy can be increased by irradiating ultraviolet rays in an ozone atmosphere. This method is also effective for electrode materials such as platinum, gold, copper, and nickel.

  In addition, the surface energy of the element chip 22 can be increased by forming a lyophilic thin film (for example, a hydrophilic film) on the surface of the element chip 22. For example, a thin film such as silicon oxide, nitrogen oxide, or titanium oxide may be formed on the surface of the element chip 22 by a vacuum sputtering method or a thermal CVD method. It is also effective to irradiate ultraviolet rays in an ozone atmosphere after forming these thin films. Also, the surface energy can be increased by modifying the surface of the element chip 22 with a silane coupling agent having an amino group, a carboxyl group or a hydroxyl group at the terminal. When surface-treating only a metal, the surface may be modified with a thiol having an amino group, a carboxyl group or a hydroxyl group at the terminal.

  As a result of experiments conducted by the present inventors, it has been found that if the length of the longest side constituting the element chip 22 is 1 mm or less, the element chip 22 is efficiently arranged in the region 12 by surface tension. In consideration of the formation and handling of the element chip 22, the length of the longest side is preferably 100 nm or more.

  In the mounting method of the present invention, since the droplet (A) containing only one element chip is arranged at a predetermined position, the element chip can be reliably mounted at a predetermined position. Therefore, unlike the conventional method, it is not necessary to prepare an excessive number of element chips. In the mounting method of the present invention, it is possible to mount different shapes and different types of element chips.

<Method for manufacturing element chip>
There is no limitation on the method for manufacturing the element chip, and a known method may be applied. Hereinafter, an example of a method for manufacturing an element chip will be described with reference to FIGS. 5A and 5C are top views, and FIGS. 5B and 5D are cross-sectional views.

  First, as shown in FIGS. 5A and 5B, a plurality of electronic elements 53 are formed on a substrate 51 having a layer 52 on the surface. Layer 52 is a selectively removable layer. Next, as shown in FIGS. 5C and 5D, a plurality of element chips 22 including one electronic element are formed by removing the layer 52. The formed element chip 22 is dispersed in a dispersion medium as necessary. Thereby, a dispersion liquid including a plurality of element chips 22 is obtained.

  An example in which the electronic element is a MOS field effect transistor (FET) is shown in the cross-sectional view of FIG. FIG. 6 shows only a part of the wafer. First, a single crystal silicon substrate 60 in which an oxide film 61 is formed in a region having a certain depth near the surface is prepared. Then, a plurality of FETs 63 are formed on the surface of the n-type silicon 62 existing on the surface of the substrate 60 (FIG. 6A). Specifically, a p-type region 64 doped with boron, a thermal oxide film 65, a source electrode 66, a drain electrode 67, and a gate electrode 68 are formed.

  Next, a groove 60h that separates the FETs 63 is formed. The groove 60h is formed so as to reach the oxide film 61 (FIG. 6B). The groove 60h can be formed by, for example, a photolithography / etching process.

  Finally, as shown in FIG. 6C, the oxide film 61 is selectively etched by, for example, hydrofluoric acid to separate each FET 63. In this way, the element chip 69 is obtained.

  There is no limitation on the method of forming an element chip such as a single crystal silicon transistor, and other methods may be used. For example, after a transistor is formed on a single crystal silicon wafer, the wafer back surface may be cut to thin the wafer, and then the wafer may be cut with a dicer. The back side of the wafer can be shaved by polishing and / or etching.

<First Example of First and Second Regions>
Hereinafter, an example of the first region 11 in which the dispersion medium 21 has low wettability and the second region 12 in which the dispersion medium 21 has high wettability will be described. The functions of these areas are shown in FIG. As shown in FIG. 7A, the second region 12 is surrounded by the first region 11. When the droplet 20 is disposed in the second region 12, the droplet 20 does not protrude from the second region 12, so that the droplet 20 is a part of the second region 12 as shown in FIG. Only placed. Therefore, the contact surface between the droplet 20 and the substrate usually coincides with the planar shape of the second region 12.

  The first region 11 can be formed, for example, by forming an organic film having low wettability of the dispersion medium 21 on the substrate. Examples of such an organic film include a polymer film having a fluoroalkyl chain, a film formed of a silane coupling agent or a thiol molecule having a fluoroalkyl chain, and a fluoroalkyl chain formed by a sol-gel method. An organic / inorganic hybrid film or the like can be used. These films have a surface energy of 10 to 25 dyne / cm and a property of repelling the dispersion medium 21.

  Examples of the polymer film having a fluoroalkyl chain include polytetrafluoroethylene, polydifluoroethylene, and derivatives thereof. When forming a liquid repellent film (for example, a water repellent film) with a silane coupling agent, the substrate is placed in chloroform, alkane, alcohol, or silicone oil in which a silane coupling agent having a fluoroalkyl chain is dissolved at a concentration of several vol%. What is necessary is just to immerse for a fixed time. In this case, it is possible to form a monomolecular film by washing the substrate with a solvent after immersion. As a substrate on which such a liquid repellent film can be formed, a substrate having active hydrogen on the surface is preferable. Examples thereof include silicon oxide, silicon nitride, stainless steel, copper, nickel, and a resin whose surface is activated. FIG. 8A schematically shows the structure of an example of a liquid-repellent monomolecular film formed with a silane coupling agent. The monomolecular film 81 in FIG. 8A is bonded to the substrate 82 through a siloxane bond (Si—O).

  When forming a liquid-repellent thin film using thiol molecules, the substrate is immersed in an ethanol or propanol solution in which a thiol molecule having a fluoroalkyl chain is dissolved at a concentration of several vol% for a certain period of time, and then the substrate is washed with alcohol. Good. Thereby, a liquid repellent monomolecular film is formed. Examples of the substrate on which these monomolecular films can be formed include a substrate made of a metal such as gold, silver, and copper. FIG. 8B schematically shows the structure of an example of a liquid repellent monomolecular film formed using thiol molecules. The monomolecular film 83 in FIG. 8B is bonded to the substrate 84 via the SH group.

  When a lyophobic thin film is formed by a sol-gel method, for example, tetraethoxysilane that is a precursor of silicon oxide, an alkoxide having a fluoroalkyl chain, an acid catalyst, an alcohol solution in which water is dissolved, What is necessary is just to apply | coat to a board | substrate by the dipping method and to heat-process at 100 degreeC or more. This liquid repellent thin film can be formed on almost any substrate.

  The lyophilic second region surrounded by the lyophobic first region is a portion that becomes a first region by preparing a lyophilic substrate or a substrate that has been lyophilic in advance. Can be produced by forming a liquid-repellent film. For example, first, a portion to be made lyophilic is covered with a protective film such as a resist. Next, after the entire substrate is covered with the liquid repellent film, the protective film is removed and the liquid repellent film in the second region is lifted off. This method can be applied to a liquid repellent film formed by using a silane coupling agent or a sol-gel method. Alternatively, a surface on which only the liquid repellent film specifically adheres may be formed in a portion to be the first region, and the liquid repellent film may be formed only in this region. For example, by forming a metal pattern that reacts with thiol only in a portion where liquid repellency is desired and immersing the substrate in an organic solvent in which thiol is dissolved, only the metal region can be made liquid repellant.

  In addition, a liquid-repellent film may be directly formed in a predetermined region by an inkjet method, a screen printing method, a relief printing method, an intaglio printing method, a micro contact printing method, or the like.

  Further, the lyophilic second region surrounded by the lyophobic first region may be formed using an inorganic material. For example, a silicon substrate has higher liquid repellency than silicon oxide. Therefore, a silicon oxide pattern may be formed on the surface of the silicon substrate, and the silicon oxide portion may be used as the second region. In this configuration, it is possible to place the droplets 20 only on the silicon oxide pattern portion. The surface energy of silicon oxide is 100 dyne / cm or more, and the surface energy of silicon is about 38 dyne / cm.

  Thus, the dispersion medium 21 can be accurately arranged in the second region 12 by forming the lyophilic second region 12 surrounded by the liquid repellent first region 11. As a result, the element chip 22 can be accurately arranged in the second region 12. According to this method, it is possible to accurately arrange the element chips without making holes in the substrate.

<Second Example of First and Second Regions>
Hereinafter, a substrate in which a first region and a second region surrounded by the first region and projecting from the first region will be described. An example of such a substrate is shown in FIG.

  On one main surface of the substrate 90 in FIG. 9A, there is a convex portion 92a protruding from the periphery. A region around the convex portion 92 a is a first region 91, and an upper surface of the convex portion 92 a is a second region 92.

  When the droplet 20 is disposed in the second region 92, the droplet 20 is disposed only in the second region 92 as shown in FIG. 9B. Therefore, when the droplet 20 including the element chip 22 is disposed in the second region 92 and the dispersion medium 21 is removed, the element chip 22 is accurately disposed in the second region 92.

  In this case, even if the surface energy of the first region 91, the surface energy of the side surface of the convex portion 92a, and the surface energy of the second region 92 are the same, the droplet 20 is unlikely to spread from the second region 92. Therefore, in this case, the element chip 22 can be disposed at a predetermined position without forming a lyophilic film or a liquid repellent film.

  The height of the convex portion 92a is preferably in the range of 0.5 to 10 μm, for example, in the range of 1 to 2 μm.

  The convex portion 92a can be formed by a known method. For example, first, a thin film that becomes the convex portion 92a is formed. For the thin film, for example, a silicon oxide film, a silicon nitride film, a metal film, or a resin film can be used. Next, the portion that becomes the protrusion 92a is covered with a resist film, the thin film in the portion where the resist film is not formed is etched, and finally the resist film is removed. In this way, the convex portion 92a can be formed.

  In addition, for example, a glass substrate may be prepared, and a silicon oxide film may be formed only on a portion to be the second region. The portion where the silicon oxide film is formed becomes the second region, and the other portion becomes the first region. The thickness of the silicon oxide film is not limited and may be 0.5 μm, for example. The silicon oxide film having a predetermined shape can be formed, for example, by forming a silicon oxide film on the entire substrate by a vacuum electron beam evaporation method and then removing an unnecessary silicon oxide film by using a photolithography method.

<Method for forming droplet (A)>
Hereinafter, the method for forming the droplet (A) will be described by taking three methods as examples.

  The first method is a method of incorporating one element chip into a dispersion medium droplet. This method is shown in FIG. First, as shown in FIG. 10A, the dispersion medium 21 is filled in a capillary (hollow tube) 101 having an inner diameter of the tip portion that is approximately the same as the dimension of the element chip. A commercially available glass tube can be used for a capillary having an inner diameter of 100 μm or more. A capillary having an inner diameter of several μm to several tens of μm can be formed by heating and stretching a part of the capillary having an inner diameter of about 100 μm with a burner.

  Next, as shown in FIG. 10B, a droplet 102 of the dispersion medium 21 is formed at the tip of the capillary 101 by applying pressure to the dispersion medium 21.

  On the other hand, a plurality of element chips 22 are arranged on the substrate 103 as shown in FIG. The element chips 22 may be randomly arranged on the substrate 103. The surface 103s of the substrate 103 is a surface (liquid repellent surface) where the dispersion medium 21 has low wettability. The element chip 22 can be disposed on the substrate 103 by, for example, dropping a liquid in which a plurality of element chips 22 are dispersed onto the substrate 103 and then removing the dispersion medium. As the substrate 103, a substrate covered with the above-described liquid repellent film, a silicon substrate, or the like can be used.

  Next, the droplet 102 formed at the tip of the capillary 101 is brought into contact with one element chip 22 on the substrate 103. At this time, since the surface of the substrate 103 is liquid repellent, the droplets 102 are not attracted to the surface of the substrate 103 and do not deviate from the tip of the capillary 101. When the droplet 102 comes into contact with the element chip 22, as shown in FIG. 10D, the element chip 22 is taken into the droplet 102, and the droplet 20 including the dispersion medium 21 and the element chip 22 is formed. .

  Next, as shown in FIG. 10E, the droplet 20 is brought to a position (second region 12) where the element chip 22 is to be mounted on the substrate 10. The second region 12 preferably has higher wettability of the dispersion medium 21 than the inner wall of the capillary 101. In such a case, at the moment when the droplet 20 comes into contact with the second region 12, the droplet 20 moves from the tip of the capillary 101 to the substrate side (FIG. 10 (f)). Thereafter, when the dispersion medium 21 volatilizes, the element chip is disposed at a predetermined position as shown in FIG.

  Other methods for disposing the element chip 22 on the substrate are shown in FIGS. A configuration of an example of a droplet discharge device used in this method is schematically shown in FIG. FIG. 11A is a perspective view of the ejection device 110 viewed from one side. FIG. 11B is an exploded perspective view of the discharge device 110. FIG.11 (c) is the perspective view which looked at the discharge apparatus 110 from the opposite side to Fig.11 (a).

  The discharge device 110 includes a base body 113 in which a groove 111 and a through hole 112 are formed. The groove 111 includes a discharge groove 111a serving as a discharge port, a tapered groove 111b, and a rear groove 111c. A liquid repellent film 114 is formed in a part of the ejection groove 111a. The inner surface of the groove 111 excluding the portion of the liquid repellent film 114 and the surface of the recess 118 described later are lyophilic. Further, the surface of the substrate 113 other than the grooves 111 and the recesses 118 is liquid repellent.

  The base 113 can be formed by processing a silicon substrate, a resin substrate, or the like. In the case of a silicon substrate, the substrate 113 can be formed by photolithography and etching (wet etching or dry etching). In the case of a resin substrate, the substrate 113 can be formed by laser processing or the like.

  Here, it is assumed that the shape of the element chip 22 is a rectangular parallelepiped shape whose sides in three directions are different from each other, and the size of the element chip 22 is defined by length, width, and thickness (length> width> thickness). Sa). The depth 111h of the groove 111 is about the thickness of the element chip 22, the width 111aD of the discharge groove 111a is about the width of the element chip 22, and the length 111aL of the discharge groove 111a is about the length of the element chip 22. By setting in this way, it is possible to prevent two or more element chips 22 from entering the ejection groove 111a at the same time. The width 111cD of the rear groove 111c may be, for example, 10 times or more the length of the element chip 22.

  A through hole 112 is formed in the rear groove 111c. The length and width of the through-hole 112 are approximately the same as the length and thickness of the element chip 22 and are sized to allow one element chip 22 to pass through.

  As shown in FIGS. 11A and 11B, a first electrode 115 is formed in the ejection groove 111a. In addition, the second electrode 116, the insulating film 117, and the liquid repellent film 114 are sequentially stacked in the ejection groove 111a. The first electrode 115 is formed on the side surface of the ejection groove 111 a and is electrically disconnected from the second electrode 116.

  FIG. 11C is a schematic view of the base 113 viewed from the back side. A recess 118 that communicates with the through hole 112 is formed on the back surface of the base 113. The recess 118 has a tapered shape. When the plate-shaped element chip 22 is arranged, the size of the recess 118 may be about 10 to 100 times the area (length × width) of the element chip 22, for example.

  In order to dispose the element chip 22 on the substrate using the discharge device 110, the discharge device 110 is disposed such that the side on which the groove 111 is formed faces the substrate, and a dispersion liquid in which a plurality of element chips 22 are dispersed. From the recess 118. Here, the discharge groove 111a is disposed below the rear groove 111c. In the method using the discharge device 110, a conductive dispersion medium is used as the dispersion medium of the dispersion liquid.

FIG. 12A schematically shows a perspective view of the discharge device 110 in which the dispersion liquid is placed as viewed from the substrate side. In FIG. 12, the groove 111 faces upward, but actually, the groove 111 side faces downward as shown in FIG.
The dispersion liquid 120 including the plurality of element chips 22 and the conductive dispersion medium 121 enters the groove 111 through the through hole 112. When the surface area of the groove 111 is small, the surface tension that attracts the dispersion liquid 120 to the groove 111 is larger than the gravity acting on the dispersion liquid 120, so that the dispersion liquid 120 does not fall down from the groove 111. The element chip 22 in the dispersion 120 fits in the ejection groove 111a from the rear groove 111c through the tapered groove 111b.

  Next, a method for ejecting a droplet containing only one element chip 22 from the ejection device 110 will be described. First, a voltage is applied between the first electrode 115 and the second electrode 116. In this state, due to the electrowetting phenomenon, electric charges are accumulated at the interface between the conductive dispersion medium 121 and the liquid repellent film 114 to increase the interfacial tension, and the liquid repellent film 114 in the ejection groove 111a is dispersed in the dispersion medium 121. It becomes easy to get wet. That is, by applying a voltage, the liquid repellent film 114 becomes lyophilic, and the dispersion medium 121 and one element chip 22 are accommodated in the ejection groove 111a. FIG. 12A shows this state.

  Next, when the applied voltage is set to 0 V, the liquid repellent film 114 repels the dispersion medium 121, so that the dispersion medium 121 on the liquid repellent film 114 becomes thermodynamically unstable, and the tapered groove 111b. Is separated from the dispersion medium 121 existing in the nozzle and discharged to the outside of the discharge device 110 (FIGS. 12B and 12C). In this way, a droplet 20 containing only one element chip 22 is formed. After that, when a voltage is applied again between the first electrode 115 and the second electrode 116, the lyophobic film 114 changes to lyophilicity due to the electwetting phenomenon, and the element chip 22 and the dispersion medium 121 are discharged again. The groove 111a is filled (FIG. 12 (d)).

  FIG. 13 schematically shows how the element chip 22 is arranged on the substrate 10 using the discharge device 110. As described above, the second region (not shown in FIG. 13) where the element chip 22 is disposed exists on the surface of the substrate 10. The discharge device 110 is moved using an X, Y, Z position control device (not shown).

  In a state where a voltage is applied between the first electrode 115 and the second electrode 116, the ejection device 110 is brought close to a predetermined position on the substrate 10. Then, the dispersion medium 121 existing in the ejection groove 111 a is brought into contact with a predetermined position of the substrate 10, and the voltage applied between the first electrode 115 and the second electrode 116 is set to 0V. Then, the dispersion medium 121 present in the ejection groove 111a moves to the lyophilic region (second region 12) of the substrate 10, and accordingly, one element chip 22 also moves. In this manner, the droplet 20 is disposed in the second region 12 of the substrate 10. Thereafter, when the dispersion medium 121 in the droplet 20 is volatilized, the element chip 22 is arranged at a predetermined position.

  When the electrowetting phenomenon is used, a conductive dispersion medium 121 is used in order to efficiently generate the electrowetting phenomenon. Examples of the conductive dispersion medium 121 include an aqueous solution in which an inorganic salt is dissolved, an organic solution in which an organic salt is dissolved, or a mixture thereof. In particular, a liquid in which no salt remains when the dispersion medium evaporates is preferable. For example, ammonia water or hydrogen peroxide water can be used.

  The amount of liquid exiting from the ejection groove 111a is controlled using the electrowetting phenomenon in the ejection device 110, but can also be controlled mechanically. For example, an apparatus provided with a shutter that stops the flow of liquid at the boundary between the ejection groove and the tapered groove may be used. When the shutter is formed of a piezoelectric material, the shutter can be opened and closed by voltage control. When the shutter is closed in a state where liquid is present in the ejection groove and the liquid in the ejection groove is brought into contact with the lyophilic substrate, only the liquid present in the ejection groove portion moves to the substrate due to capillary action. Thereafter, when the shutter is opened with the ejection groove separated from the substrate, the ejection groove is again filled with liquid. By repeating this operation, a predetermined liquid can be disposed at an arbitrary position on the substrate.

  Examples of the present invention that can be implemented will be described below. However, the present invention is not limited to the following examples.

Example 1
In this embodiment, an example of a liquid crystal display will be described. FIG. 14 schematically shows a part of the configuration of the liquid crystal display 140.

  The liquid crystal display 140 includes a glass substrate 141, an X driver 142, a Y driver 143, an X scan electrode 144, a Y scan electrode 145, a transistor chip 146, and a pixel portion 147. The transistor chip 146 is a transistor formed in single crystal silicon.

  The pixel portion 147 is controlled by a transistor chip 146 disposed in the vicinity thereof. A voltage for driving the pixel portion 147 is applied to the source electrode or the drain electrode of the transistor, and the voltage is applied from the X driver 142 via the X scanning electrode 144. An image signal voltage is applied to the gate electrode from the Y driver 143 via the Y scanning electrode 145. A voltage is applied from a transistor to which the voltage of the image signal is applied to a pixel electrode (not shown) under the pixel. On the other hand, although not shown in the figure, a transparent electrode is disposed on the pixel electrode via a liquid crystal layer or an alignment film. Accordingly, when a voltage is applied to the pixel electrode, a voltage is applied to the liquid crystal layer and the light transmittance changes.

(Manufacturing method of liquid crystal display)
Below, an example of the manufacturing method of the liquid crystal display 140 is demonstrated. FIG. 15 is a schematic cross-sectional view of the liquid crystal display 140, and shows only the vicinity of two pixels. Note that a process other than the arrangement of the transistor chip on the substrate can be performed by a general method.

  First, an X scan electrode 144, a Y scan electrode 145, and a pixel electrode 151 are formed on a glass substrate 141 having a 50 cm square and a thickness of 1 mm by using a photolithography method. Copper is used as the electrode material, and the thickness of the electrode is 50 nm. The line width of the X scan electrode 144 and the Y scan electrode 145 is 2 μm. The size of the pixel electrode 151 is 100 μm × 100 μm.

  The X scan electrode 144 and the Y scan electrode 145 are arranged in a grid as shown in FIG. An insulating film (not shown) is formed at a location where the X scan electrode 144 and the Y scan electrode 145 intersect. Both electrodes are insulated from each other by this insulating film. Silicon nitride or silicon oxide can be used for the insulating film. Next, the transistor chip 146 is disposed. The transistor chip 146 has a structure shown in FIG. In this specification, the source electrode and the drain electrode are described separately, but either of them may be a source electrode, and if one is a source electrode, the other works as a drain electrode.

  The arrangement of the electrodes of the transistor chip 146 is schematically shown in FIG. The transistor chip 146 has a plate shape, a size of 20 μm × 5 μm, and a thickness of 1 μm. The transistor has a channel length of 2 μm and a channel width of 10 μm. A source electrode 146s, a drain electrode 146d, and a gate electrode 146g are formed on one surface of the transistor.

  As shown in FIG. 15, the electrodes are formed so that the gate electrode of the transistor corresponds to the X scan electrode, and the source electrode and the drain electrode correspond to the Y scan electrode and the pixel electrode.

  When the transistor chip 146 is mounted by the mounting method of the present invention, there are a case where the surface on which the electrode terminal is formed faces the glass substrate 141 side and a case where the surface faces in the opposite direction. For example, in FIG. 15, the left transistor chip 146 has a surface on which the electrode terminals are formed facing the glass substrate 141, and the right transistor chip 146 faces the opposite direction. Therefore, when the transistor chip 146 is disposed on the substrate, no wiring is connected to the right transistor chip 146. Such wiring to the transistor chip 146 is performed after the transistor chip 146 is arranged.

  After the transistor chip 146 is disposed, the smooth layer 152 is formed so as to cover the entire surface of the substrate. Next, a through hole is formed in the smooth layer 152 in order to perform wiring to the electrode of the transistor chip 146. Since the thickness of the transistor chip 146 is 1 μm, the smoothing layer 152 is necessary for wiring the transistor chip 146. The smooth layer 152 plays a role of fixing the transistor to the substrate. As the material of the smooth layer 152, a thermosetting polymer material, an ultraviolet curable polymer material, a sol-gel film formed using a metal alkoxide, or the like can be used. In particular, a polymer material that can be processed by photolithography is preferable, and photocurable polyimide or the like is preferable. Before the smooth layer 152 is formed, since the adhesion between the transistor chip 146 and the substrate is weak, the smooth layer 152 is preferably formed by spray coating, for example.

  Next, the X scan electrode 144, the Y scan electrode 145, and the pixel electrode 151 are formed on the smooth layer 152. The pattern of these electrodes on the smooth layer 152 is the same as the pattern of the copper electrode formed on the glass substrate 141, and both are electrically connected at the glass edge.

  The electrode on the smooth layer 152 is connected to the source electrode, the drain electrode, and the gate electrode of the transistor chip whose electrode terminals face upward through through holes. As described above, in the manufacturing method of this embodiment, the transistor chip 146 is connected to the wiring regardless of which direction the electrode terminal of the transistor chip 146 is disposed with respect to the glass substrate 141.

  Next, an alignment film 153 is formed. On the other hand, a polarizing plate 155, a transparent electrode 156, a color filter 157, and an alignment film 158 are formed on the glass substrate 154. Next, the glass substrate 141 and the glass substrate 154 are bonded to each other with a spacer interposed therebetween. After that, liquid crystal 159 is injected into a gap between the glass substrate 141 and the glass substrate 154 and sealed with a sealant 160. In this way, a liquid crystal display is obtained.

(First mounting method of transistor chip)
Below, an example of the method of arrange | positioning a transistor chip on the glass substrate 141 is typically shown to Fig.16 (a)-(e).

  First, as shown in FIG. 16A, an X scan electrode 144, a Y scan electrode 145, and a pixel electrode 151 are formed on a glass substrate 141 by using a photolithography method. These electrodes are formed in a shape that can be connected to the source electrode, drain electrode, and gate electrode on the surface of the transistor chip 146 disposed on the glass substrate 141.

  Next, a lyophilic region 162 where the transistor chip 146 is disposed and a lyophobic region 161 surrounding the region 162 are formed. The regions 161 and 162 can be formed by the following method.

First, the entire glass substrate 141 on which the electrode is formed is irradiated with ultraviolet rays in an ozone atmosphere to make the surface of the glass substrate 141 and the surface of the electrode lyophilic. By this treatment, the surface energy of the glass surface can be increased to 100 dyne / cm or more. Next, a portion other than the region to be made liquid repellent is covered with a positive resist film. Next, the glass substrate is immersed in a perfluorooctane solution in which 1 vol% of CF ₃ (CF ₂ ) ₇ C ₂ H ₄ SiCl ₃ is dissolved in a dry atmosphere for 20 minutes. The glass substrate is immersed in pure perfluorooctane for 5 minutes, and then the solvent is removed. Next, the positive resist film is removed. By this step, the region not covered with the resist film becomes the liquid repellent region 161. The surface energy of the liquid repellent region 161 is, for example, 19 dyne / cm.

  An example of the shape of the liquid repellent region 161 and the lyophilic region 162 is shown in FIG. A region 161 is formed so as to surround the region 162. In FIG. 17, illustration of electrodes on the substrate is omitted, but among the electrodes on the substrate, the electrodes corresponding to the source electrode and the drain electrode of the transistor chip exist across both the region 161 and the region 162. . That is, there are lyophilic portions and lyophobic portions on the electrode surfaces. The surface of the clean copper electrode is lyophilic, but it can be made liquid repellent by reacting the surface with a silane coupling agent to form a liquid repellent monomolecular film. Therefore, it is possible to form a copper electrode having both a liquid repellent region and a lyophilic region by reacting the silane coupling agent only on a predetermined region of the copper electrode surface.

  Next, a plurality of transistor chips manufactured by the method shown in FIG. 6 are dispersed in pure water to prepare a dispersion. Next, the dispersion liquid is placed on a tetrafluoroethylene substrate, and the moisture is evaporated, thereby randomly arranging the transistor chips on the tetrafluoroethylene substrate. Next, this tetrafluoroethylene substrate is irradiated with ultraviolet rays in an ozone atmosphere to make the surface of the transistor chip on the substrate lyophilic. The surface energy of the lyophilic transistor chip is, for example, 70 dyne / cm or more.

  Next, as shown in FIG. 18A, a glass capillary 181 having an inner diameter of the nozzle tip of 30 μm, an inner diameter of the nozzle end of 500 μm, and a length between both ends of 5 mm is prepared. Nitrogen gas at a constant pressure can be sent from the gas pressure controller 182 to the nozzle end of the capillary 181 through the gas introduction tube 183.

FIG. 18B is a schematic cross-sectional view of the tip of the capillary 181. The capillary 181 includes a glass tube 181a, a copper thin film 181b and a liquid repellent monomolecular film 181c formed on the outer surface of the glass tube 181a. The monomolecular film 181c can be formed of CF ₃ (CF ₂ ) ₇ C ₂ H ₄ SH.

  Next, after filling the capillary 181 with pure water, the gas pressure controller 182 applies pressure to the capillary 181 to form a droplet 184 having a diameter of 30 μm at the tip of the capillary 181. The surface tension of pure water is 72 dyne / cm. Since the periphery of the tip of the capillary 181 is covered with a liquid repellent monomolecular film 181c, the droplet 184 remains as a droplet at the tip of the capillary 181 as shown in FIG.

  Next, when the capillary 181 is brought close to the vicinity of the tetrafluoroethylene substrate on which the transistor chip is arranged using an XYZ position controller (not shown) and the droplet 184 is brought into contact with the transistor chip, the transistor chip is brought into the liquid. Be drawn. When this droplet is brought into contact with the lyophilic region 162 of the glass substrate 141 shown in FIG. 16B, the droplet including the transistor chip is arranged there. The droplets are disposed in all the regions 162 where the transistor chips are to be disposed. If the liquid droplets are left for a while after the liquid droplets are placed, the water droplets are volatilized, and the transistor chip is accurately placed in the region 162.

  Thereafter, as described above, the smooth layer 152 and the electrode are formed (FIGS. 16D and 16E). In this way, the transistor chip is mounted.

(Second mounting method of transistor chip)
A method for mounting a transistor chip using the discharge device 110 shown in FIGS. 11 to 13 will be described below.

  An example of the size of the discharge device 110 is shown in FIG. The discharge device 110 can be formed, for example, by processing a silicon substrate. A plurality of ejection devices may be formed on one silicon wafer. In this case, grooves and recesses are formed on both sides of the silicon wafer.

  Hereinafter, an example of a manufacturing method of a discharge device using a 500 μm thick silicon wafer having a (100) surface and a 2 μm thick thermal oxide film formed on both surfaces will be described.

  First, a mask for forming a groove having a predetermined shape is formed on the surface of the silicon wafer. A copper thin film (thickness: 100 nm) having a predetermined pattern is used for the mask. Note that the mask is such that the end of the ejection groove 111a comes to the end face of the silicon wafer.

  Next, the thermal oxide film and silicon in the portion where the copper thin film is not formed are etched by dry etching. The etching depth is 6 μm. Thereafter, the copper thin film is removed with a 1 wt% aqueous ferric chloride solution. Thus, the groove 111 is formed on one side of the silicon wafer.

  Next, the recess 118 is formed on the surface of the silicon wafer where the groove is not formed. Specifically, first, a copper thin film mask is formed. Next, only the portion of the thermal oxide film where the copper thin film is not formed is removed by dry etching. Thereafter, the copper thin film is removed with a 1 wt% aqueous ferric chloride solution. Thus, a pattern of a thermal oxide film having a hole is formed on the back side of the silicon wafer. Next, in order to prevent deterioration of the groove 111 in the next step, the entire groove 111 is covered with an epoxy resin. Thereafter, by immersing the silicon wafer in an 80 ° C. KOH solution, the region without the thermal oxide film is anisotropically etched, and a tapered recess 118 is formed. Etching is performed until the recess 118 is connected to the groove 111. By optimizing the shape of the outermost surface hole on the recess 118 side, the shape of the through hole 112 can be 2 μm × 25 μm. Thereafter, the epoxy resin covering the groove 111 is removed. Thus, the groove 111, the recess 118, and the through hole 112 are formed.

  Next, the first and second electrodes 115 and 116 are formed using a photolithography method. Next, a silicon oxide film (insulating film 117) is formed only over the second electrode 116. Next, a copper thin film is formed only on the surface 113e where the end of the ejection groove 111a exists by an electron beam evaporation method.

Next, in a dry atmosphere, the silicon wafer is immersed in a perfluorooctane solution in which 1 vol% of CF ₃ (CF ₂ ) ₇ C ₂ H ₄ SiCl ₃ is dissolved, and washed with perfluorooctane. CF ₃ (CF ₂ ) ₇ C ₂ H ₄ SiCl ₃ reacts with the substrate surface on which active hydrogen such as a hydroxyl group or an amino group is present to form a liquid repellent monomolecular film as shown in FIG. Form. Here, the inner wall portion of the groove 111 is silicon and there is no active hydrogen. On the other hand, active hydrogen exists on the surface of the thermal oxide film, the surface of the silicon oxide film, the surface of the first electrode 115, and the surface of the copper thin film existing on the surface 113e. Accordingly, these treatments render these surfaces lyophobic. As a result, even if the groove 111 is filled with the liquid, the liquid does not protrude from the groove 111 and spill out. Further, as described above, the discharge device of FIG. 19 can discharge droplets using the electrowetting phenomenon. Here, a liquid repellent film is also formed over the first electrode 115, but the film is thin and thus electrically conductive with the liquid.

  The transistor chip can be disposed at a predetermined position on the substrate as described with reference to FIG. The angle formed between the surface 113s of the ejection device in FIG. 19 and the substrate when the transistor chip is disposed is, for example, 30 °. As the dispersion medium in which the transistor chip is dispersed, for example, a 0.5 vol% ammonium hydroxide aqueous solution is used.

(Example 2)
Below, an example of an organic electroluminescent display (organic EL display) is demonstrated. The configuration of the organic EL display 200 is schematically shown in FIG.

  The display 200 includes a substrate 201 made of polycarbonate, an X driver 202, a Y driver 203, an X scanning electrode 204, a Y scanning electrode 205, an element chip 206, and a pixel unit 207. The element chip 206 includes a transistor circuit formed in crystalline silicon. The pixel portion 207 includes an organic EL material. The pixel unit 207 is controlled by a transistor circuit of the element chip 206.

  A circuit diagram of a transistor circuit for controlling the pixel portion 207 is shown in FIG. This circuit includes a switching transistor 211, a driver transistor 212, and a capacitor. The pixel portion 207 is controlled by two transistors, a switching transistor 211 and a driver transistor 212. A voltage is applied to the source electrode of the switching transistor 211 from the Y driver 203 via the Y scanning electrode 205. The drain electrode of the transistor 211 and the gate electrode of the transistor 212 are electrically connected. The drain electrode of the driver transistor 212 is electrically connected to a pixel electrode (not shown in FIG. 21) disposed under the pixel portion 207. In addition, a voltage for causing the pixel to emit light is applied to the source electrode of the driver transistor 212. On the other hand, an image signal (voltage) is applied from the X driver 202 to the gate electrode of the switching transistor 211 via the X scanning electrode 204.

  When the voltage of the image signal is applied to the switch transistor 211, the voltage is applied from the transistor 211 to the gate electrode of the driver transistor 212. As a result, a voltage is applied to the pixel electrode. Although not shown in FIG. 21, a transparent electrode is disposed on the pixel portion 207. Accordingly, when a voltage is applied to the pixel electrode, the pixel portion 207 emits light.

  A perspective view of the element chip 206 is schematically shown in FIG. The element chip 206 is formed of plate-like single crystal silicon. The element chip 206 has a length of 20 μm, a width of 5 μm, and a thickness of 1 μm. On the surface of the element chip 206, one electrode terminal 206x, two electrode terminals 206y, and two electrode terminals 206d are formed. These electrode terminals are arranged twice symmetrically with respect to the surface on which the electrode terminals are formed. When the element chip is disposed on the EL display substrate, the electrode terminal 206x is connected to the X scan electrode, the electrode terminal 206y is connected to the Y scan electrode, the electrode terminal 206d is connected to the driver electrode, and the display is driven. .

(Method for manufacturing organic EL display)
Below, an example of the manufacturing method of an organic electroluminescent display is demonstrated. A cross-sectional view of the organic EL display 200 of the present invention is shown in FIG. FIG. 22 shows only the vicinity of two pixels. In addition, about the process except arrangement | positioning of the element chip | tip on a board | substrate, it can carry out by a general method.

  First, a silicon oxide film 221 is formed on a polycarbonate substrate 201 having a 50 cm square and a thickness of 1 mm. Next, a driver electrode (not shown) for applying a voltage to the X scan electrode 204, the Y scan electrode 205, the pixel electrode 222, and the driver transistor is formed on the silicon oxide film 221. These electrodes are formed using a photolithography method. The electrode material is copper and the thickness is 50 nm. The line widths of the X / Y scan electrodes and the driver electrodes are 2 μm. The size of the pixel electrode 222 is 100 μm × 100 μm. An insulating film is formed at the intersection of the X scan electrode, the Y scan electrode, and the driver electrode to insulate the electrodes. Silicon nitride or silicon oxide can be used for the insulating film.

  Next, in the same manner as in Example 1, the region where the element chip 206 is arranged is made lyophilic, and the region surrounding it is made lyophobic. The surface energy of the lyophobic region can be about 20 dyne / cm, and the surface energy of the lyophilic region can be 60 dyne / cm or more. Then, the element chip 206 whose surface has been made lyophilic is disposed at a predetermined position by the same method as the first mounting method of the transistor chip described in the first embodiment.

  The surface energy of the element chip 206 can be set to 50 dyne / cm or more by lyophilic treatment. Similar to the first embodiment, the element chip 206 has a case where the surface on which the electrode terminal is formed faces the substrate 201 side and a case where it faces the opposite. In the left element chip 206 of FIG. 22, the electrode terminal faces the substrate 201 side, and the right element chip 206 faces the opposite. Therefore, the element chip 206 on the left side of FIG. 22 is connected to the electrode on the substrate. On the other hand, the element chip 206 on the right side of FIG. 22 is connected to an electrode in a later step. Note that the electrode terminals of the element chip 206 are arranged so as to be twice symmetrical with respect to the surface on which the element chip 206 is formed. Can be connected to.

  After disposing the element chip 206, a smooth layer 223 is formed on the entire surface of the substrate. Next, a through hole reaching the electrode terminal of the element chip is formed in the smooth layer 223. The smooth layer 223 can be formed using the materials described in Embodiment 1. Since the thickness of the element chip 206 is 1 μm, such a smooth layer 223 is necessary. The smooth layer 223 plays a role of fixing the element chip 206 to the substrate.

  Next, an X scan electrode 204, a Y scan electrode 205, a driver electrode (not shown), and a pixel electrode 222 are formed on the smooth layer 223. These electrode patterns are the same as the electrode patterns formed directly on the substrate. The electrode on the smooth layer 223 and the electrode on the substrate are electrically connected at the substrate end (not shown). The electrode on the smooth layer 223 is electrically connected to the electrode terminal of the element chip 206 in which the electrode terminal faces the side opposite to the substrate 201 side through the through hole. As described above, in this embodiment, the element chip 206 can be connected to the electrode regardless of the orientation of the main surface of the element chip 206 with respect to the substrate 201.

  After the insulating layer 224 is formed, an organic EL film 225 to be a light emitting layer is formed using a shadow mask. Next, a transparent electrode 226 and a silicon oxide film 227 are formed. In this way, an organic EL display can be manufactured.

  The element chip 206 may be mounted by another mounting method of the present invention. For example, you may mount by the method similar to the 2nd mounting method of the transistor chip demonstrated in Example 1. FIG. Further, instead of the element chip 206, a switch transistor chip and a driver transistor chip may be separately manufactured and separately disposed at predetermined positions on the substrate. In this case, it is necessary to change the arrangement of the electrodes, but the transistor chip can be mounted by the same method as described above.

  Although the embodiments of the present invention have been described with examples, the present invention is not limited to the above-described embodiments, and can be applied to other embodiments based on the technical idea of the present invention.

  The present invention can be applied to an element chip mounting method. Further, the present invention can be applied to a circuit board and an electronic device including the circuit board. For example, the present invention can be applied to a method for manufacturing a circuit board and an electronic device including the circuit board, and a method for repairing the circuit board and the electronic device including the circuit board.

It is a figure which shows typically an example of the method of this invention for mounting an element chip. It is a figure explaining the method of FIG. It is another figure explaining the method of FIG. It is another figure explaining the method of FIG. It is a figure which shows typically an example of the method of forming an element chip. It is sectional drawing which shows typically an example of the manufacturing method of the transistor chip using a single crystal silicon. It is a figure which shows typically an example of the area | region where a droplet is arrange | positioned, and (b) the state of the droplet arrange | positioned in the area | region. It is a figure which shows typically the structure of a liquid-repellent organic thin film. (A) It is a figure which shows typically another example of the area | region where a droplet is arrange | positioned, and (b) the state of the droplet arrange | positioned in the area | region. It is a figure which shows typically an example of the arrangement | positioning method of the element chip using a capillary. It is a figure which shows typically the structure of an example of the discharge device for arrange | positioning an element chip. It is a figure which shows typically the method of forming the droplet containing an element chip using the discharge apparatus of FIG. It is a figure which shows typically a mode that an element chip is arrange | positioned using the discharge apparatus of FIG. It is a top view which shows typically the structure of an example of the liquid crystal display of this invention. It is sectional drawing which shows the liquid crystal display of FIG. 14 typically. It is sectional drawing which shows typically an example of the method of mounting a transistor chip on a board | substrate. It is a top view which shows typically an example of the lyophilic area | region (2nd area | region) surrounded by the liquid-repellent area | region (1st area | region). It is a figure which shows typically an example of the capillary used for arrangement | positioning of an element chip. It is a figure which shows an example of the size of the discharge apparatus used for arrangement | positioning of an element chip. It is a top view which shows typically the structure of an example of the electroluminescent display of this invention. (A) It is a figure which shows typically the arrangement | positioning of the circuit near the pixel of the display of FIG. 20, and (b) the electrode terminal of an element chip. It is sectional drawing which shows the display of FIG. 21 typically.

Explanation of symbols

10, 90, 103 Substrate 10s Main surface 11, 91 First region 12, 92 Second region 20 Liquid droplet (Liquid droplet (A))
21, 121 Dispersion medium 22, 69, 146, 206 Element chip 81, 83 Monomolecular film 92a Convex part 101 Capillary 102 Droplet (Droplet (B))
103a Surface (surface with low wettability of dispersion medium)
110 Discharge device 111 Groove 111a Discharge groove 111b Tapered groove 111c Rear groove 112 Through hole 113 Base 114 Liquid repellent film 118 Recess 146 Transistor chip 181 Capillary 200 Organic EL display

Claims (18)

A mounting method for mounting an element chip containing an electronic element on a substrate,
(I) placing a droplet (A) including a dispersion medium and only one of the element chips placed in the dispersion medium on one main surface of the substrate;
(Ii) mounting the element chip on the substrate by removing the dispersion medium from the droplet (A). On the one principal surface, there are a first region and a second region surrounded by the first region and having a higher wettability of the dispersion medium than the first region,
The mounting method according to claim 1, wherein the droplet (A) is disposed in the second region in the step (i).   The mounting method according to claim 2, wherein an organic film in which the wettability of the dispersion medium is lower than that of the second region is formed in at least a part of the first region. On the one main surface, there is a first region and a second region that is surrounded by the first region and protrudes from the first region,
The mounting method according to claim 1, wherein the droplet (A) is disposed in the second region in the step (i). The element chip has a rectangular parallelepiped shape including two surfaces (P1), two surfaces (P2) having an area equal to or larger than the surface (P1), and two surfaces (P3) having an area larger than the surface (P2). Has the shape of
The shape of the surface (P3) and the shape of the second region where the droplet (A) is disposed are substantially equal,
The mounting method according to any one of claims 2 to 4, wherein one of the two surfaces (P3) is disposed so as to face the one main surface by the step (ii).   The mounting method according to claim 5, wherein the shape of the surface (P3) is a rectangle. An electrode is formed in the second region,
The mounting method according to claim 5 or 6, wherein an electrode terminal is formed on one of the two surfaces (P3). After the step (ii),
The mounting method according to claim 7, further comprising a step of forming an electrode that passes over a surface of the two surfaces (P3) far from the substrate. Before the step (i),
(A) disposing at least one element chip on one surface of the dispersion medium having low wettability;
(B) taking one said element chip | tip arrange | positioned on the said surface in the droplet (B) of the said dispersion medium, and forming the said droplet (A). The mounting method according to Item 1. The dispersion medium has electrical conductivity;
The step (i) includes a step of forming the droplet (A) from a liquid including the dispersion medium and the plurality of element chips dispersed in the dispersion medium using an electrowetting phenomenon. The mounting method according to claim 1.   The mounting method according to claim 1, wherein the dispersion medium has a property of taking the element chip into the inside thereof.   The mounting method according to claim 1, wherein a substrate of the element chip is made of single crystal silicon. Before the step (i),
The mounting method according to claim 12, further comprising: forming the element chip by cutting the single crystal silicon substrate after forming a plurality of the electronic elements on the single crystal silicon substrate.   The mounting method according to claim 1, wherein the electronic element is a transistor. A method of manufacturing an electronic device including a substrate and an element chip that includes the electronic element and is mounted on the substrate,
The manufacturing method of an electronic device including the process of mounting the said element chip by the mounting method of any one of Claims 1-14.   The manufacturing method according to claim 15, wherein the electronic device is a display device.   A display device manufactured by the manufacturing method according to claim 16. A display device comprising a substrate, a plurality of transistor chips mounted on the substrate, and first and second wirings for controlling the transistor chips,
The transistor chip includes electrode terminals formed only on one main surface thereof,
The first wiring is disposed between the substrate and the transistor chip;
The second wiring is disposed on the opposite side of the substrate from the transistor chip;
Each of the plurality of transistor chips is a display device electrically connected to one of the first wiring and the second wiring through the electrode terminal.