JP2005144217A - Thin film forming method, manufacturing method of device, manufacturing method of electro-optical device and electronic device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thin film forming method using an ink jet technique and suitable for micronization or the enhancement of film physical properties. <P>SOLUTION: In a drying process of a liquid droplet LH, the convection in the liquid droplet is controlled using the temperature distribution in the liquid droplet. Concretely, pinning and depinning are controlled by controlling the temperature of a substrate S or the atmospheric temperature of the liquid droplet LH or partially heating the liquid droplet LH by a laser. By this method, the thin film having a desired shape is formed on the substrate. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a thin film forming method, a device manufacturing method, an electro-optical device manufacturing method, and an electronic apparatus.

An electro-optical device used as a display, a display light source, or the like, or an electronic device such as a semiconductor device includes a process of arranging a material on a substrate and forming a film on the substrate in the manufacturing process. Material placement technology and film formation technology are closely related to quality and function, and are important for improving the performance of each of the above devices.
As a technique for arranging a material on a substrate, there is a method of discharging a liquid material as droplets through a nozzle provided in an ejection head (for example, Patent Document 1). This droplet discharge method is advantageous in that it consumes less liquid material and can easily control the amount and position of the liquid material placed on the substrate, compared to a technique such as spin coating.
Japanese Patent Laid-Open No. 11-274671

In the technique of forming a film on a substrate using the droplet discharge method, placement accuracy is required when a liquid material is placed on the substrate, but the film is miniaturized and the film properties are improved after the liquid film is dried. Is required.
The present invention has been made in view of such circumstances, and an object thereof is to provide a thin film forming method suitable for miniaturization and improvement of film physical properties.
Another object of the present invention is to provide a device manufacturing method, an electro-optical device, and an electronic apparatus capable of improving quality.

  In order to solve the above problems, a thin film forming method of the present invention is a method of forming a thin film on a substrate by placing a liquid material in droplets on a substrate and drying the droplets. In the drying process of the droplet, the convection in the droplet is controlled using the temperature distribution in the droplet.

  FIG. 11 is a diagram showing a general drying process of droplets. Such droplets generally dry faster at the edges. For this reason, in the initial stage of drying, the liquid rapidly evaporates at the edge of the droplet, and the solid concentration tends to increase. At this time, when the solid content concentration at the edge of the droplet reaches the saturation concentration, the solid content locally precipitates at the edge. Then, the edge of the droplet is pinned by the deposited solid content, and the contraction of the droplet (the contraction of the outer diameter) accompanying the subsequent drying is suppressed. Hereinafter, this phenomenon, that is, the phenomenon in which the shrinkage of the droplet due to drying is suppressed by the solid content deposited at the edge is referred to as “pinning”, and the phenomenon in which the droplet shrinks without pinning during drying is referred to as “depinning”. Call it. On the other hand, when a predetermined temperature difference is given in the fluid, energy transfer cannot be achieved only by thermal diffusion of the fluid, and the fluid becomes unstable such as convection.

The present invention controls this pinning and depinning by controlling the convection in the droplet. Therefore, according to this method, a dry film having an arbitrary shape and size can be formed. For example, when the liquid is continuously convected during the drying period, the droplets continue to contract without causing pinning, so that the size of the obtained dry film becomes extremely small. Further, when pinning occurs, the pinned solid content can be scraped off (ie, depinned) by intensifying the convection at the initial stage. On the other hand, when convection is intense, the deposition of solids can be stabilized by reducing the temperature distribution in the droplets and making the convection gentle. That is, the film quality can be controlled by optimally setting the size of the convection. In addition to maintaining convection, it is possible to freely control the shape and size of the dry film by intentionally stopping convection (ie, adjusting the timing to stop convection control within the droplet). Is possible.
In particular, in this method, since convection can be forcibly caused by temperature control, a depinning thin film can be formed even when, for example, specific heat is high and pinning occurs only by natural drying. In addition, a high boiling point solvent or a high boiling point dispersion medium is usually used for a liquid material used in an ink jet apparatus, but such a liquid material has a long drying time, and during this time, convection in a droplet stops (that is, Pinning may occur). Therefore, even in such a case, if this method is used, a minute thin film can be formed without causing pinning.

  By the way, the state of the temperature distribution in the droplet differs depending on the type of the liquid. For example, since drying proceeds generally faster at the bottom of the droplet, the temperature tends to be lower than the top of the droplet due to heat of vaporization. However, as will be described in [Best Mode for Carrying Out the Invention] in the next section, when the boiling point of the liquid is low (for example, less than 150 ° C.), the heat of the substrate is not transferred to the top of the droplet. As evaporation continues, the top of the droplet is coldest. Conversely, when the boiling point of the liquid is high (for example, the boiling point is 150 ° C. or higher), the drying proceeds slowly, so that the heat of the substrate is easily transferred to the top of the droplet, and the temperature of the droplet is approximately within the droplet. It becomes uniform or gets colder at the edge.

  For this reason, when using a high boiling point solvent or high boiling point dispersion medium (for example, a solvent or dispersion medium having a boiling point of 150 ° C. or higher) such that the top of the droplet has a relatively high temperature, It is preferable that convection is generated in the droplet by giving a temperature gradient such that the top of the droplet is hotter than the bottom. Of course, even if a temperature gradient is applied to such a droplet so that the temperature at the top is lower than that at the bottom to reverse the temperature distribution, convection can be generated in the droplet, but more efficiently. In order to cause convection, it is desirable to employ the method described above. Similarly, when a low boiling point solvent or a low boiling point dispersion medium (for example, a solvent or dispersion medium having a boiling point of less than 150 ° C.) in which the temperature at the top of the droplet is relatively low is used, Thus, it is preferable that a convection is generated in the droplet by providing a temperature gradient such that the top portion is cooler than the bottom portion.

  In this case, it is desirable to control the temperature difference between the top and bottom of the droplet to 0.5 ° C. or more. Whether or not convection occurs in the droplet depends on the temperature gradient in the droplet and the viscosity of the liquid material. For example, when the temperature gradient in the droplet is large, convection is more likely to occur, and when the viscosity of the liquid material is large, this acts as a resistance, so that convection is less likely to occur. However, the viscosity of a liquid usually used in an ink jet apparatus or the like is about 0.5 to 50 cps. If the liquid has such a viscosity, the above temperature gradient, that is, 0.5 ° C. or more at the top and bottom of the droplet If the temperature gradient is given, sufficient convection can be generated.

The following method can be employed as a method for controlling the temperature of the droplet.
(1) A method for controlling the temperature of the substrate on which the droplets are arranged (2) A method for partially heating the droplets by laser (3) A method for controlling the atmospheric temperature of the droplets For example, a low boiling point solvent or a solvent Alternatively, when a low-boiling point dispersion medium is used, in the method (1), the temperature of the bottom of the droplets may be increased by heating the substrate. In the method (2), a laser beam is irradiated substantially parallel to the substrate to heat the bottom side of the droplet. In the method (3), the atmospheric temperature may be lower than the substrate temperature to cool the top of the droplet. On the other hand, when a high-boiling point solvent or a high-boiling point dispersion medium is used as the solvent or dispersion medium, convection can be promoted by applying a temperature gradient opposite to that when a low-boiling point solvent or low-boiling point dispersion medium is used. . That is, in the method (1), the substrate may be cooled to lower the temperature of the bottom of the droplet, and in the method (2), the top of the droplet is heated by applying laser light to the top of the droplet. To do. In the method (3), the top of the droplets may be warmed by setting the ambient temperature higher than the substrate temperature. In the method (3), only the temperature near the droplet may be controlled by downflow.

The device manufacturing method of the present invention is characterized in that a device is manufactured using the thin film formed by the above-described method. According to another aspect of the invention, there is provided a method for manufacturing an electro-optical device, wherein the electro-optical device is manufactured using the thin film formed by the above-described method.
Examples of these devices include semiconductor elements, imaging elements, liquid crystal elements, and organic EL elements. Examples of the electro-optical device include a liquid crystal display device, an organic EL display device, an electrophoretic display device, and a plasma display device.
According to this method, since a high-definition film pattern can be formed by the above-described thin film forming method, the quality of devices and electro-optical devices can be improved.

According to another aspect of the invention, an electronic apparatus includes the above-described electro-optical device.
Thereby, an electronic apparatus provided with a high-quality display unit can be provided.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all of the following drawings, the film thicknesses and dimensional ratios of the respective components are appropriately changed in order to make the drawings easy to see.

[Thin film formation method]
In the thin film forming method of the present invention, a liquid material containing a functional material is ejected (arranged) as droplets on a substrate by a droplet ejection device and dried to form a film. At this time, in the present invention, the convection state of the droplet is controlled using the temperature distribution in the droplet during the drying process.

  Usually, a temperature difference is partially generated in the droplet due to the effect of heat of vaporization, and this kind of temperature difference causes two types of convection, Rayleigh convection and Marangoni convection, in the droplet. Rayleigh convection is convection due to buoyancy caused by local density differences in the droplets, and Marangoni convection is convection caused by local surface tension differences at the gas-liquid interface. In general, Rayleigh convection is dominant when the droplet size is large, and Marangoni convection is dominant when the droplet size is small. In the droplet discharge device handled in the present embodiment, for example, an ink jet device, the size of the discharged droplet is sufficiently small, so Marangoni convection is dominant. Therefore, in this embodiment, this Marangoni convection is used to control pinning and depinning at the periphery of the droplet.

  FIG. 1 is a schematic view showing an example of a drying process in the thin film forming method of the present invention. In FIG. 1, when a droplet discharged onto a substrate is dried, a microfilm is formed by continuously generating convection in the droplet. That is, in this example, in order to prevent solid content precipitation (pinning) at the edge of the droplet in the initial stage of drying, a temperature distribution higher than a predetermined temperature is generated in the droplet, and convection is generated at the edge of the droplet. Prompts. When such temperature control is performed, a convection including a flow of liquid from the center to the edge and a flow from the edge to the center is continuously formed in the droplet, and a local convection is formed in the droplet. Increase in the solid content concentration is suppressed, and the solid content concentration in the droplets is made uniform. Then, when the solid content concentration of the entire droplet reaches the saturation concentration almost simultaneously, precipitation occurs almost simultaneously in the entire droplet. At this time, solidification occurs while maintaining the shape of the droplet in the contraction process of the droplet, and the dry film has a film thickness approximately the same at the center and the edge, or at the center compared to the edge. Becomes larger.

Here, as a method for controlling the temperature distribution in the droplet, the following method can be used.
(1) Method for controlling temperature of substrate on which droplets are arranged (2) Method for partially laser heating droplets (3) Method for controlling ambient temperature of droplets

At this time, in order to efficiently generate convection, it is desirable to change the temperature control method according to the characteristics of the solvent or dispersion medium of the liquid material (mainly the boiling point of the solvent or dispersion medium). Below, the relationship between the boiling point of a solvent or a dispersion medium and the temperature distribution in a droplet is demonstrated.
Table 1 below shows the relationship between the type of the solvent or dispersion medium, the convection state, and the temperature distribution on the droplet surface. Here, a liquid material prepared by dispersing polystyrene fine particles (particle diameter φ = 1.5 μm) in several kinds of dispersion media was prepared. The concentration of the fine particles is 0.1 wt%. Then, 2 μl of each liquid material was taken with a micropipette, dropped onto the substrate and observed with a microscope from directly above. The substrates used were Si substrates, glass substrates, and glass substrates that were surface-treated with SAMs (SAMs: FAS17, C18, CN, Bz, FAS3, C8, NH2).

FAS17 = 1H, 1H, 2H, 2H-perfluorodecyltriethoxysilane, C18 = octadecyltrimethoxysilane, CN = 3-cyanopropyltriethoxysilane, Bz = benzyltriethoxysilane, F3 = 3, 3, 3 Trifluoropropylmethoxysilane, C8 = octyltriethoxysilane, NH2 = 3-aminopropyltriethoxysilane.
In Table 1, state A indicates that convection at the droplet surface occurs from the outer periphery (edge) of the bottom of the droplet toward the top of the droplet, and convection at the center of the droplet is What is generated from the top toward the center of the bottom of the droplet is shown (see FIG. 10A). In state B, convection on the droplet surface occurs from the top of the droplet toward the outer periphery of the bottom of the droplet, and convection at the center of the droplet occurs from the center of the bottom of the droplet to the top of the droplet. What is generated is shown (see FIG. 10B). In addition, the state C shows a state in which almost no convection is observed in the droplet (see FIG. 10C).

  Further, here, the temperature distribution on the surface of the droplet was observed using thermography. As a result, in the droplet showing the state A, the temperature at the top of the droplet is lower than the temperature at the edge of the droplet, and in the droplet showing the state B, the temperature distribution is opposite to that in the state A. That is, it was found that the temperature at the top of the droplet was higher than the temperature at the edge of the droplet. In addition, in the droplet showing the state C, there was almost no temperature difference in the droplet, and the temperature distribution was almost uniform.

From the above results, the following is considered.
(1) Marangoni convection mainly occurs in the droplet.
In other words, in this example, a flow (thermocapillary flow) from the higher temperature to the lower temperature is generated on the droplet surface, which is one of the features of Marangoni convection. Therefore, the convection in the droplet is Rayleigh convection. It can be seen that Marangoni convection is dominant. Further, since the convection is a thermocapillary flow, the temperature distribution at the gas-liquid interface is important.
(2) Convection in the droplet is mainly caused by temperature distribution inside the droplet.
This is concluded from the fact that convection does not occur when the temperature in the droplet is substantially uniform (ie, indicates state C). On the contrary, it can be seen from this that the temperature of the droplets can be controlled to control the convection.
(3) The direction of convection in the droplet is closely related to the boiling point of the solvent or dispersion medium.
That is, when the relationship between the convection state and the boiling point of the solvent or dispersion medium is observed, the convection pattern is reversed at 150 ° C. When a solvent or dispersion medium having a boiling point of 150 ° C. or higher is called a high boiling solvent or high boiling dispersion medium, and a solvent or dispersion medium having a boiling point of less than 150 ° C. is called a low boiling solvent or low boiling dispersion medium, it is generally a high boiling solvent or high boiling dispersion. In the case of using a medium, the convection pattern is in state B, and in the case of using a low boiling point solvent or a low boiling point dispersion medium, it is in state A. In Table 1, there are some that do not comply with this, but such a solvent or dispersion medium originally has a property that a temperature distribution is difficult to occur, such as a large specific heat.

  As described above, the temperature distribution in the droplet varies depending on the solvent or dispersion medium. Therefore, when the convection is controlled by partially applying heat to the droplet, the heating position is determined depending on the type of the solvent or dispersion medium. In particular, it should be varied based on the boiling point of the solvent or dispersion medium. For example, in order to widen the temperature gradient in the droplet, in the case of using a high boiling point solvent or a high boiling point dispersion medium, the droplet is given a temperature gradient such that the top is higher than the bottom, In the case of using a low-boiling point solvent or a low-boiling point dispersion medium, it is only necessary to give a temperature gradient such that the top part has a lower temperature than the bottom part. As a result, convection in the droplet is promoted and pinning is less likely to occur. On the contrary, when the control opposite to this is performed, the convection is weakened and pinning becomes easy. By properly using these controls, a film having a desired size can be obtained.

Specific modes of temperature control are shown in FIGS. FIG. 2 shows a method using a high boiling point solvent or a high boiling point dispersion medium, and FIG. 3 shows a method using a low boiling point solvent or a low boiling point dispersion medium.
FIG. 2A shows a method of controlling the temperature distribution in the droplet LH by the temperature of the substrate S. Here, since the high boiling point solvent or the high boiling point dispersion medium is used as the solvent or the dispersion medium, for example, when the substrate temperature is raised (heated), the temperature gradient in the droplet LH becomes small and the convection becomes weak (that is, pinning occurs). Easier). Further, when the substrate temperature is lowered (cooled), the temperature gradient in the droplet LH increases, and convection is promoted (ie, depinning).
FIG. 2B shows a method for controlling the temperature distribution in the droplet LH by laser heating. In this method, for example, irradiating the laser beam to the substrate S substantially in parallel and heating only the top of the droplet LH can promote convection in the droplet LH.
FIG. 2C shows a method for controlling the temperature distribution in the droplet LH by controlling the ambient temperature. In this method, for example, by making the ambient temperature higher than the substrate temperature, the top of the droplet LH is warmed and convection is promoted. Further, the convection can be weakened by setting the atmospheric temperature lower than the substrate temperature. In this method, only the temperature near the droplet may be controlled by downflow.

On the other hand, when the low boiling point solvent or the low boiling point dispersion medium is used, when the substrate S is cooled, the temperature gradient in the droplet LC is decreased, and thus the convection is weakened. When the substrate S is heated, the temperature gradient is increased. Convection is promoted (FIG. 3 (a)). Similarly, when the temperature of the droplet LC is higher than the substrate temperature and the top of the droplet LC is warmed, the temperature gradient in the droplet LC becomes smaller and the convection becomes weaker. When the top of the droplet LC is cooled at a lower temperature, the convection becomes stronger (FIG. 3B).
Note that when the boiling point is sufficiently small, evaporation always occurs at the top of the droplet, so that a large temperature gradient is generated in the droplet due to the heat of vaporization. For this reason, when a solvent or dispersion medium having a sufficiently low boiling point is used, it may be possible to form a depinning thin film without performing temperature control such as substrate heating.

As described above, in the thin film forming method of this example, pinning and depinning are controlled using convection in the droplets, so that a dry film having an arbitrary shape and size can be formed. For example, when the liquid is continuously convected during the drying period, the droplets continue to contract without causing pinning, so that the size of the obtained dry film becomes extremely small. Further, when pinning occurs, the pinned solid content can be scraped off (ie, depinned) by intensifying the convection at the initial stage. On the other hand, when convection is intense, the deposition of solids can be stabilized by reducing the temperature distribution in the droplets and making the convection gentle. That is, the film quality can be controlled by optimally setting the size of the convection. In addition to maintaining convection, it is possible to freely control the shape and size of the dry film by intentionally stopping convection (ie, adjusting the timing to stop convection control within the droplet). Is possible.
In particular, in this method, since convection can be forcibly caused by temperature control, a depinning thin film can be formed even when, for example, the specific heat is high and pinning occurs only by natural drying. In addition, a high boiling point solvent or a high boiling point dispersion medium is usually used for a liquid material used in an ink jet apparatus, but such a liquid material has a long drying time, and during this time, convection in a droplet stops (that is, Pinning may occur). Therefore, even in such a case, if this method is used, a minute thin film can be formed without causing pinning.

[Proximity arrangement method of multiple dry films]
Next, a method for forming a plurality of thin films side by side on a substrate will be described. FIG. 4 is a view for explaining a method for forming the depinning thin films close to each other, wherein the upper stage is a plan view and the lower stage is a cross-sectional view.
When a plurality of droplets are arranged side by side on a substrate and then dried together, it is necessary to separate the droplets more than the diameter of the droplets in order to avoid bonding of the droplets before drying. . Bonding (merging) of droplets before drying leads to enlargement of the film. Therefore, in this method, a plurality of dry films are formed close to each other by drying the droplets previously placed on the substrate and then placing the next droplet.

  That is, in this method, as shown in FIG. 4, first, a first droplet is placed on a substrate, and a dry film (first dry film) of the first droplet is formed. Then, the second droplet is placed on the substrate so as to partially overlap the first dry film, and dried to form a dry film (second dry film) of the second droplet. At this time, the convection state in the second droplet is optimally controlled so that the edge of the second droplet is not pinned by the first dry film. Specifically, when a high-boiling solvent or high-boiling point dispersion medium is used as the solvent or dispersion medium for the second droplet, the substrate temperature or the atmospheric temperature is controlled, or the droplet is partially laser-heated. As a result, a temperature gradient is applied to the second droplet such that the top of the second droplet is hotter than the bottom. On the other hand, when a low boiling point solvent or a low boiling point dispersion medium is used, a temperature gradient is applied so that the top part is at a lower temperature than the bottom part. As a result, convection in the second droplet is promoted, and the first dry film is prevented from acting as a pinning site. Therefore, by adopting this method, the second dry film can be formed close to and side by side with the first dry film.

[Formation method of linear pattern]
Next, a method for forming a linear pattern on the substrate will be described. FIG. 5 is a diagram illustrating an example of a method of forming a linear pattern using the above-described method of arranging a plurality of dry films in close proximity. Here, for example, a pattern is formed using a film forming apparatus 10 as shown in FIG.

[Film forming equipment]
First, the film forming apparatus 10 will be described.
In FIG. 6, the film forming apparatus 10 is provided on a base 112, a substrate stage 22 that supports the substrate 20, and is interposed between the base 112 and the substrate stage 22, and can move the substrate stage 22. A first moving device (moving device) 114 supported by the substrate stage, a liquid ejecting head 21 capable of ejecting the processing liquid to the substrate 20 supported by the substrate stage 22, and a first supporting device movably supporting the liquid ejecting head 21. A two-movement device 116 and a control device 23 for controlling the droplet discharge operation of the liquid discharge head 21. Further, the film forming apparatus 10 includes an electronic balance (not shown) as a weight measuring device provided on the base 112, a capping unit 25, and a cleaning unit 24. The operation of the film forming apparatus 10 including the first moving device 114 and the second moving device 116 is controlled by the control device 23.

  The first moving device 114 is installed on the base 112 and is positioned along the Y direction. The second moving device 116 is mounted upright with respect to the base 112 using the support columns 16A and 16A, and is mounted at the rear portion 12A of the base 112. The X direction (second direction) of the second moving device 116 is a direction orthogonal to the Y direction (first direction) of the first moving device 114. Here, the Y direction is a direction along the front 12B and rear 12A directions of the base 112. On the other hand, the X direction is a direction along the left-right direction of the base 112 and is horizontal. The Z direction is a direction perpendicular to the X direction and the Y direction.

  The first moving device 114 is constituted by, for example, a linear motor, and includes guide rails 140 and 140 and a slider 142 provided to be movable along the guide rail 140. The slider 142 of the first moving device 114 of this linear motor type can be positioned by moving in the Y direction along the guide rail 140.

  Further, the slider 142 includes a motor 144 for rotating around the Z axis (θZ). The motor 144 is, for example, a direct drive motor, and the rotor of the motor 144 is fixed to the substrate stage 22. Thus, by energizing the motor 144, the rotor and the substrate stage 22 can rotate along the θZ direction to index (rotate index) the substrate stage 22. That is, the first moving device 114 can move the substrate stage 22 in the Y direction (first direction) and the θZ direction.

  The substrate stage 22 holds the substrate 20 and positions it at a predetermined position. The substrate stage 22 has a suction holding device (not shown), and the suction holding device operates to suck and hold the substrate 20 on the substrate stage 22 through the hole 46A of the substrate stage 22.

  The second moving device 116 is constituted by a linear motor, and is supported by a column 16B fixed to the columns 16A and 16A, a guide rail 62A supported by the column 16B, and movable in the X direction along the guide rail 62A. The slider 160 is provided. The slider 160 can be positioned by moving in the X direction along the guide rail 62 </ b> A, and the liquid discharge head 21 is attached to the slider 160.

  The liquid discharge head 21 has motors 62, 64, 67, 68 as swing positioning devices. If the motor 62 is operated, the liquid ejection head 21 can be positioned by moving up and down along the Z axis. The Z axis is a direction (vertical direction) orthogonal to the X axis and the Y axis. When the motor 64 is operated, the liquid discharge head 21 can be positioned by swinging along the β direction around the Y axis. When the motor 67 is operated, the liquid discharge head 21 can be positioned by swinging in the γ direction around the X axis. When the motor 68 is operated, the liquid discharge head 21 can be positioned by swinging in the α direction around the Z axis. That is, the second moving device 116 supports the liquid discharge head 21 so as to be movable in the X direction (first direction) and the Z direction, and can move the liquid discharge head 21 in the θX direction, the θY direction, and the θZ direction. To support.

  6 can be positioned by moving linearly in the Z-axis direction in the slider 160, and can be positioned by swinging along α, β, and γ. The droplet discharge surface 11P can be accurately controlled in position or posture with respect to the substrate 20 on the substrate stage 22 side. A plurality of nozzles for discharging droplets are provided on the droplet discharge surface 11P of the liquid discharge head 21.

  The liquid discharge head 21 discharges a liquid material (resist) from a nozzle by a so-called liquid discharge method (droplet discharge method). As the liquid ejection method, various known techniques such as a piezo method that ejects ink using a piezoelectric element as a piezoelectric element, and a method that ejects liquid material using bubbles generated by heating the liquid material are applied. it can. Among these, the piezo method has an advantage that it does not affect the composition of the material because no heat is applied to the liquid material. In this example, the piezo method is used.

  FIG. 7 is a view for explaining the discharge principle of the liquid material by the piezo method. In FIG. 7, a piezo element 32 is installed adjacent to a liquid chamber 31 for storing a liquid material. The liquid material is supplied to the liquid chamber 31 via a liquid material supply system 34 including a material tank that stores the liquid material. The piezo element 32 is connected to a drive circuit 33, and a voltage is applied to the piezo element 32 via the drive circuit 33. By deforming the piezo element 32, the liquid chamber 31 is deformed and the liquid material is discharged from the nozzle 30. At this time, the amount of distortion of the piezo element 32 is controlled by changing the value of the applied voltage, and the speed of distortion of the piezo element 32 is controlled by changing the frequency of the applied voltage. That is, in the liquid ejection head 21, the ejection of the liquid material from the nozzle 30 is controlled by controlling the voltage applied to the piezo element 32.

  Returning to FIG. 6, the electronic balance (not shown) measures, for example, 5000 drops from the nozzle of the liquid discharge head 21 in order to measure and manage the weight of one drop discharged from the nozzle of the liquid discharge head 21. Receive a minute drop. The electronic balance can accurately measure the weight of one droplet by dividing the weight of the 5000 droplet by the number of 5000. Based on the measured amount of droplets, the amount of droplets ejected from the liquid ejection head 21 can be optimally controlled.

  The cleaning unit 24 can perform cleaning of the nozzles of the liquid discharge head 21 periodically or at any time during the device manufacturing process or during standby. The capping unit 25 covers the droplet discharge surface 11P during standby when the device is not manufactured in order to prevent the droplet discharge surface 11P of the liquid discharge head 21 from drying.

  By moving the liquid discharge head 21 in the X direction by the second moving device 116, the liquid discharge head 21 can be selectively positioned above the electronic balance, the cleaning unit 24, or the capping unit 25. That is, even during the device manufacturing operation, the weight of the droplet can be measured by moving the liquid discharge head 21 to the electronic balance side, for example. If the liquid discharge head 21 is moved onto the cleaning unit 24, the liquid discharge head 21 can be cleaned. If the liquid discharge head 21 is moved onto the capping unit 25, a cap is attached to the droplet discharge surface 11P of the liquid discharge head 21 to prevent drying.

  That is, the electronic balance, the cleaning unit 24, and the capping unit 25 are disposed on the rear end side on the base 112 and directly below the movement path of the liquid discharge head 21 and separated from the substrate stage 22. Since the supply work and the discharge work of the substrate 20 with respect to the substrate stage 22 are performed on the front end side of the base 112, the electronic balance, the cleaning unit 24, or the capping unit 25 does not hinder the work.

  As shown in FIG. 6, a preliminary discharge area (preliminary discharge) in which the liquid discharge head 21 discards or trially discharges (preliminary discharge) droplets on a portion of the substrate stage 22 other than supporting the substrate 20. (Region) 152 is provided separately from the cleaning unit 24. As shown in FIG. 6, the preliminary discharge area 152 is provided along the X direction on the rear end side of the substrate stage 22. This preliminary discharge area 152 is fixed to the substrate stage 22 and has a concave-shaped receiving member that opens upward, and an absorbent material that is exchangeably installed in the concave portion of the receiving member and absorbs the discharged droplets. It is composed of

  Returning to FIG. 5, the linear pattern forming method of this embodiment will be described. Here, the liquid material is discharged from the discharge head 21 as droplets, and the droplets are arranged on the substrate 21 at regular intervals (pitch). Then, a linear film pattern is formed on the substrate 21 by repeating this droplet placement operation.

  Specifically, first, as shown in FIG. 5A, the droplets L1 ejected from the ejection head 21 are sequentially arranged on the substrate 21 with a predetermined interval.

  After the droplet L1 is placed on the substrate 21, a drying process is performed in order to remove liquid components (solvent, dispersion medium, etc.). The drying process may be performed by moving the stage on which the substrate 21 is mounted, in addition to a general heating process using heating means such as a hot plate, an electric furnace, a hot air generator, and lamp annealing. In this example, as described above, the droplets are contracted to form a dry film (depinning).

  Next, as shown in FIG. 5B, the above-described droplet placement operation is repeated. That is, as in the previous time shown in FIG. 5A, the liquid material is discharged from the discharge head 21 as droplets L2, and the droplets L2 are arranged on the substrate 21 at regular intervals. At this time, the amount of the droplet L2 (the amount of the liquid material per droplet) and the arrangement pitch P2 thereof are the same as the previous droplet L1. Further, the arrangement position of the droplet L2 is shifted by a predetermined distance S1 from the previous droplet L1. That is, the center position of the previous droplet L1 disposed on the substrate 21 and the center position of the current droplet L2 are in a positional relationship separated by the distance S1. In this example, the shift amount S1 is narrower than the pitches P1 and P2 (S1 <P1 = P2), and the next droplet L2 partially overlaps the droplet L1 previously disposed on the substrate 21. It has been established.

  At this time, the current droplet L2 and the previous droplet L1 are in contact with each other. However, since the liquid component of the previous droplet L1 has already been completely or removed to some extent, they merge and spread on the substrate 21. There is hardly anything. After the droplet L2 is placed on the substrate 21, a drying process is performed in the same manner as before to remove the liquid component.

  Thereafter, as shown in FIG. 5C, the above-described droplet placement operation is repeated a plurality of times. At each time, the distance interval (pitch Pn) between the droplets Ln to be arranged is the same as the distance of the first time (pitch Pn = P1), and is always constant. Further, when the droplet placement operation is repeated a plurality of times, the position where the placement of the droplet Ln is started is shifted by a predetermined distance from the position where the previous droplet was placed each time. By repeating this droplet placement operation, the gaps between the droplets placed on the substrate 21 are filled, and a linear continuous pattern is formed. In addition, the film pattern formed on the substrate is always formed by droplet arrangement with the same pitch, and the whole undergoes almost the same formation process, so that the structure is uniform.

As described above, in the linear pattern forming method of this example, the droplets are contracted to form the dry film, so that the dry film of each droplet can be miniaturized. Therefore, a high-definition film pattern can be formed.
In addition, the formation method of a linear pattern is not limited to what was shown in FIG. For example, the arrangement pitch of the droplets and the shift amount at the time of repetition can be arbitrarily set.

[Electro-optical device]
Next, the device of the present invention will be described. Here, an electro-optical device, particularly a liquid crystal display device will be described as an example of this device.
FIG. 8 is a perspective view illustrating the configuration of a liquid crystal display device equipped with a color filter manufactured using the film forming method of the present invention.
The liquid crystal display device 400 according to this embodiment is equipped with auxiliary elements such as a liquid crystal driving IC (not shown), wirings (not shown), a light source 470, and a support (not shown).
The configuration of the liquid crystal display device 400 will be briefly described. The liquid crystal display device 400 includes a color filter 460 and a glass substrate 414 arranged so as to face each other, a liquid crystal layer (not shown) sandwiched therebetween, and an upper surface side (observer side) of the color filter 460. Are mainly composed of a polarizing plate 416 attached to the lower surface of the glass substrate 414 and a polarizing plate (not shown) attached to the lower surface side of the glass substrate 414. The color filter 460 includes a substrate 461 made of transparent glass and is a substrate provided on the viewer side, and the glass substrate 414 is a transparent substrate provided on the opposite side.

A partition wall 462 made of a black photosensitive resin film, a colored portion 463, and an overcoat layer 464 are sequentially formed below the substrate 461, and a driving electrode 418 is formed below the overcoat layer 464. ing. Note that in the actual liquid crystal device, an alignment film is provided on the liquid crystal layer side and the electrode 432 described later on the glass substrate 414 side so as to cover the electrode 418, but illustration and description thereof are omitted.
The liquid crystal driving electrode 418 formed on the liquid crystal layer side of the color filter 460 is formed by forming a transparent conductive material such as ITO (Indium Tin Oxide) on the entire surface of the overcoat layer 464.

An insulating layer 425 is formed on the glass substrate 414, and a TFT (Thin Film Transistor) as a switching element and a pixel electrode 432 are formed on the insulating layer 425.
A scanning line 451 and a signal line 452 are formed in a matrix over the insulating layer 425 formed over the glass substrate 414, and a pixel electrode 432 is formed for each region surrounded by the scanning line 451 and the signal line 452. Is provided. A TFT is incorporated in a corner portion of each pixel electrode 432 and a portion between the scanning line 451 and the signal line 452, and the TFT is turned on or off by applying a signal to the scanning line 451 and the signal line 452. Thus, energization to the pixel electrode 432 is controlled.

  Since the electro-optical device of this example includes the color filter formed by the thin film forming method of the present invention, high-definition display is possible.

[Electronics]
Next, the electronic apparatus of the present invention will be described.
FIG. 9 is a perspective view illustrating the configuration of a mobile phone as an example of an electronic apparatus using the liquid crystal display device. In the figure, a cellular phone 92 is provided with the above-described liquid crystal display device 400 as well as a plurality of operation buttons 921, an earpiece 922 and a mouthpiece 923.
Since the electronic apparatus of this example includes the above-described electro-optical device in the display unit, high-definition display is possible.

  The application of the droplet discharge device is not limited to the patterning of the color filter used in the electro-optical device, and can be used to form various film patterns as follows. For example, it can be used for forming thin films such as an organic EL layer and a hole injection layer included in an organic EL (electroluminescence) display panel. When forming an organic EL layer, for example, a droplet containing an organic EL material such as a polythiophene-based conductive polymer is discharged toward a region partitioned by a partition formed on the substrate, and the droplet is discharged. Place in the area. The organic EL layer is formed by drying the liquid material arranged in this way.

  Other uses of the droplet discharge device include the formation of devices such as antennas included in auxiliary wiring for transparent electrodes included in plasma displays and IC (integrated circuit) cards. Specifically, after a solution obtained by mixing conductive fine particles such as silver fine particles in an organic solution such as tetradecane is patterned using a droplet discharge device, a metal thin film layer is formed when the organic solution is dried.

  In addition to the above, the droplet discharge device can be used for various types of materials such as thermosetting resins and ultraviolet curable resins used for three-dimensional modeling, microlens array materials, and biological substances such as DNA (deoxyribonucleic acid) and proteins. It can also be used for arrangement of various materials.

  In addition to mobile phones, electronic devices include computers, projectors, digital cameras, movie cameras, PDAs (Personal Digital Assistants), in-vehicle devices, copying machines, audio devices, and the like.

  The preferred embodiments of the present invention have been described above with reference to the accompanying drawings, but it goes without saying that the present invention is not limited to such examples. Various shapes, combinations, and the like of the constituent members shown in the above-described examples are examples, and various modifications can be made based on design requirements and the like without departing from the gist of the present invention.

The figure which shows typically the drying process of the typical droplet in the thin film formation method of this invention. The schematic diagram for demonstrating the convection control method of a droplet. The schematic diagram for demonstrating the convection control method of a droplet. The figure for demonstrating the method for forming a some thin film near and arranging. The figure which shows an example of the procedure of the method of forming a linear film | membrane pattern on a board | substrate. The figure which shows the structural example of the film | membrane formation apparatus used suitably for the film | membrane formation method of this invention. The figure for demonstrating the discharge principle of the liquid material by a piezo system. 1 is a perspective view illustrating a configuration of a liquid crystal display device that is an example of an electro-optical device of the invention. FIG. 11 is a perspective view illustrating a configuration of a mobile phone that is an example of the electronic apparatus of the invention. The schematic diagram which shows the state of the convection in a droplet. The figure which shows the general drying process of the droplet in a conventional method.

Explanation of symbols

20, S ... Substrate, 92 ... Electronic equipment, 400 ... Electro-optical device (device), LC, LH ... Droplet

Claims (11)

A method of forming a thin film on a substrate by placing a liquid material in droplets on a substrate and drying the droplets,
A method of forming a thin film, wherein in the drying process of the droplet, the convection in the droplet is controlled by utilizing the temperature distribution in the droplet.   Using a liquid material solvent or dispersion medium having a boiling point of 150 ° C. or higher, and applying a temperature gradient such that the top of the droplet is higher than the bottom, convection is generated in the droplet. The thin film forming method according to claim 1, wherein the thin film forming method is performed.   Using a liquid material having a boiling point of less than 150 ° as a solvent or dispersion medium for the liquid material, a convection is generated in the droplet by giving a temperature gradient such that the top of the droplet is cooler than the bottom. The thin film forming method according to claim 1, wherein the thin film forming method is performed.   The thin film forming method according to claim 1, wherein the temperature control of the droplet is performed by controlling the substrate temperature.   4. The thin film forming method according to claim 1, wherein the temperature control of the droplet is performed by partially irradiating the droplet with a laser.   The method for forming a thin film according to any one of claims 1 to 3, wherein the temperature control of the droplets is performed by controlling the atmospheric temperature.   The method for forming a thin film according to any one of claims 1 to 6, wherein the temperature difference between the top and bottom of the droplet is controlled to 0.5 ° C or more.   The thin film forming method according to claim 1, wherein the shape of the dry film is controlled by adjusting a timing at which convection control in the droplet is stopped.   A device manufacturing method, wherein a device is manufactured using a thin film formed by the method according to claim 1.   An electro-optical device manufacturing method, wherein the electro-optical device is manufactured using the thin film formed by the method according to claim 1. An electronic apparatus comprising the electro-optical device manufactured by the method according to claim 10.

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