JP2003260408A - Thin film forming method, electronic device forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To form a thin film of a compound with a low molecular weight at a prescribed position on a substrate. <P>SOLUTION: A substrate face is divided into a plurality of regions and after a droplet is formed in one region, the next droplet formation is carried out in another region. Accordingly, droplets are formed on neighboring positions in the respective regions with time intervals and after a droplet 1-1 is dried, formation of a neighboring droplet 1-2 is carried out. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention discharges a solution in which a thin film forming material is dissolved in a solvent to arrange a plurality of droplets of the solution on a substrate and evaporate the solvent from each droplet. Thus, the present invention relates to a thin film forming method for forming a thin film on the substrate.

[0002]

2. Description of the Related Art Conventionally, a thin film formed by an ink jet method is a thin film made of a polymer compound. A thin film made of such a polymer compound is easily formed by arranging a solution in which a polymer compound is dissolved in a solvent on a substrate by an inkjet method and then evaporating the solvent from the arranged solution.

The following is prior art document information related to the invention of this application.

[0004]

[Patent Document 1] Japanese Patent Laid-Open No. 11-40358

[Patent Document 2] Japanese Patent Laid-Open No. 11-54272

[0005]

However, a compound having a small molecular weight (hereinafter,
It is referred to as a "low molecular weight compound". ) Is used to form a thin film by the same method as in the case of the above-mentioned polymer compound,
A thin film of a low molecular weight compound is not formed, and particles of a low molecular weight compound are deposited on the substrate. This is because the cohesive force between the low-molecular weight compounds is much larger than the force at which the low-molecular weight compounds are bonded to the substrate, even if the substrate is lyophilic.

As described above, the low molecular weight compound can be said to be a material having high crystallinity because of its high cohesive force. The high crystallinity is a great advantage in the function such as conductivity. Therefore, a method capable of forming a thin film of a low molecular weight compound is desired. In addition, when droplets are arranged on the substrate by ejecting the solution by the inkjet method, the partial pressure of the gas composed of the same component as the solvent of the solution forming the droplets becomes uneven around the droplets. If so, the droplets are distorted, and the droplets are likely to move to the higher partial pressure. Such movement of droplets is particularly likely to occur when a solution of a low molecular compound having a weak bonding force with the substrate is discharged. Then, if the movement of the droplet occurs, it becomes difficult to form a thin film at a predetermined position on the substrate.

For example, when a plurality of liquid droplets are formed along a certain line with a slight interval, the partial pressure around the liquid droplet formed at the end of the line is the same as that of the adjacent liquid droplets. Is low on the side where there are no droplets and high on the side where droplets are present next to it, so that it is non-uniform. This is because the solvent vapor evaporated from the adjacent droplet increases the partial pressure of the gas on the side where the droplet is present next to the periphery of the droplet formed at the end of the line.

On the other hand, in many electronic devices, a functional thin film is patterned and used, but even if a crystalline organic thin film is formed by a vacuum deposition method or the like, a unique condition is required or it is used. There are restrictions on materials. Furthermore, since the organic thin film has low resist resistance, it is difficult to perform patterning by a general patterning method including a photolithography process and an etching process.

On the other hand, if the crystalline thin film can be formed by the ink jet method, it becomes easy to form the patterned crystalline organic thin film, which is difficult with the conventional technique. An object of the present invention is to provide a thin film forming method for forming a thin film on a substrate by arranging a plurality of droplets of a solution in which a thin film forming material is dissolved in a solvent and evaporating the solvent from each droplet. In order to form a thin film of a low-molecular compound at a predetermined position on the substrate by making the partial pressure of the gas around the droplet formed on the substrate uniform and preventing the movement of the droplet as described above. That is, a patterned crystalline thin film (particularly an organic thin film) can be easily formed by an inkjet method.

[0010]

In order to solve the above-mentioned problems, according to the present invention, a plurality of droplets of the solution are arranged on a substrate by discharging a solution in which a thin film forming material is dissolved in a solvent. In the method of forming a thin film on the substrate by evaporating the solvent from each droplet, the solvent has a vapor pressure of 1.3 × 10 ⁻³ Pa at the time of discharge.
There is provided a thin film forming method characterized by using a low vapor pressure solvent having a (1 × 10 ⁻⁵ mmHg) or less.

According to this method, since it is difficult for the solvent to evaporate from each droplet, even if the adjacent droplet is formed at a relatively close position, each solvent is evaporated from the adjacent droplet. Not easily affected by steam. Therefore, it is possible to prevent the liquid droplets from moving even with the liquid droplets formed at the end of the line as described above. The present invention also discharges a solution in which a thin film forming material is dissolved in a solvent to arrange a plurality of droplets of the solution on the substrate, and evaporates the solvent from each droplet to deposit on the substrate. In the method for forming a thin film, after forming a first droplet, a second droplet is formed.
There is provided a thin film forming method characterized in that the first droplet is formed at a position separated from the formation position of the first droplet by a predetermined distance (a sufficient distance that the influence of the solvent vapor evaporated from the first droplet can be ignored). .

According to this method, the formation of the second droplet is
To prevent the liquid droplets from moving, even if they are the liquid droplets formed at the end of the line as described above, by performing the operation at a position that is not affected by the solvent vapor evaporated from the first liquid droplets. You can In addition, when the interval between adjacent droplets is shorter than a predetermined distance (a distance sufficient to ignore the influence of the solvent vapor evaporated from the first droplet), the first droplet is placed at a certain position in this method. After forming the second liquid droplet, the next second liquid droplet is formed not at the adjacent liquid droplet forming position but at the position separated by the predetermined distance from the first liquid droplet forming position, and the adjacent liquid droplet is formed. The drop formation location can be accommodated by forming the drop after the first drop has dried.

According to the present invention, a solution in which the thin film forming material is dissolved in a solvent is ejected, a plurality of droplets of the solution are arranged on a substrate, and the solvent is evaporated from each droplet. In a method for forming a thin film on a substrate, a method for forming a thin film, characterized in that the second droplet is formed at a position adjacent to the first droplet after the first droplet has been dried. .

According to this method, since the droplets (second droplets) formed later are formed after the droplets (first droplets) formed next to each other are dried, each droplet is formed. Are less affected by the solvent vapor evaporated from the adjacent droplet. Therefore,
As described above, it is possible to prevent the liquid droplets from moving even with the liquid droplets formed at the end of the line. Examples of the thin film forming material that can be used in the method of the present invention include oligophenylene or its derivative, or oligothiophene or its derivative. Oligophenylene is represented by the following formula (1), oligothiophene is represented by the following formula (2), and in each case, n is 2 or more.
In any case, it is preferable that n is 2 or more and 6 or less.

[0015]

[Chemical 1]

[0016]

[Chemical 2]

Examples of oligophenylene include p-terphenyl represented by the following formula (3). Examples of oligothiophene include terthiophene represented by the following formula (4). Examples of the oligophenylene derivative include 4-amino-p-terphenyl represented by the following formula (5). An example of the oligothiophene derivative is represented by the following formula (6):
2 ': 5', 2 "-terthiophene-5,5" -dicarboxaldehyde.

[0018]

[Chemical 3]

[0019]

[Chemical 4]

[0020]

[Chemical 5]

[0021]

[Chemical 6]

Examples of the thin film forming material usable in the method of the present invention include Alq3 (quinolinol-aluminum complex) represented by the following formula (7).

[0023]

[Chemical 7]

The present invention also provides a method of forming an electronic device, which comprises the step of forming a thin film by the method of the present invention.

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below. <First Embodiment> Terthiophene (2,2 ': 5', 2 "-terthiophene, a thin film forming material) having a structure represented by the chemical formula (3) is added to dodecylbenzene (solvent) at a concentration of 0. 1
A solution was obtained by dissolving the solution so that the weight% was obtained. Vapor pressure of dodecylbenzene at 20 ℃ (temperature at the time of discharge) is 1.3 ×
It is 10 ⁻³ Pa (1 × 10 ⁻⁵ mmHg).

Also, the wavelength of 172n is formed on the surface of the silicon substrate.
This surface was rendered lyophilic (property of being easily wetted by the solution) by irradiating it with ultraviolet light of m. The solution is applied to the surface of this silicon substrate by Seiko Epson Corporation.
Using the inkjet device "MJ-930C" manufactured by
The amount of discharge was 20 picoliters per drop. This discharge was performed in a room at 20 ° C.

As the head of this ink jet device, one having one nozzle was used. This discharge is
The distance between the nozzle of the head and the substrate is 1 mm, and the head is 70 μm with a discharge amount of 20 picoliter per droplet.
Discharging the solution was repeated 10 times while moving along one side of the substrate. As a result, 10 droplets were formed on the silicon substrate along a straight line at a pitch of 70 μm. Next, parallel to this straight line and 70 μm
Ten droplets were formed at a pitch of 70 μm along the separated straight line. By repeating this 10 times, droplets of 10 columns × 10 rows were formed on the silicon substrate at a pitch of 70 μm.

Next, the solvent was dried from the droplets by leaving it standing in this state. At that time, it was confirmed that all the formed droplets did not move and remained at each droplet forming position. After evaporation of the solvent, a thin film of terthiophene was formed at each droplet formation position. However, this terthiophene thin film is not a crystalline thin film,
It was an amorphous thin film.

Next, as a solution for the comparative example, 1,2,3,4-tetramethyl having a vapor pressure of 26 Pa (0.2 mmHg) at 20 ° C. (temperature at the time of discharge) was used in place of dodecylbenzene. Using benzene as a solvent, a terthiophene solution having a concentration of 0.1% by weight was obtained. Pitch 70 was formed on the silicon substrate in the same manner as above except that this solution was used.
Droplets of 10 columns × 10 rows having a size of μm were formed, and the solvent was dried from the droplets by allowing the droplets to stand in this state.

At this time, among the formed 10-column × 10-row droplets, all the rows of the first column, all the rows of the tenth column, and the first and tenth rows of the second to ninth columns. It was confirmed that the droplets of No. 2 were moving. That is, the liquid droplets in the portion located on the outer periphery were moving. <Second Embodiment> A of the structure represented by the chemical formula (7)
lq3 (quinolinol-aluminum complex; thin film forming material) was dissolved in 2,3-dihydrobenzofuran (solvent) to a concentration of 0.1% by weight to obtain a solution.
The vapor pressure of 2,3-dihydrobenzofuran at 25 ° C. (temperature at the time of discharge) is 1.3 × 10 ² Pa (1 × 10 ⁻¹ mm
Hg).

Further, a wavelength of 172n is formed on the surface of the silicon substrate.
This surface was rendered lyophilic (property of being easily wetted by the solution) by irradiating it with ultraviolet light of m. The solution is applied to the surface of this silicon substrate by Seiko Epson Corporation.
Using the inkjet device "MJ-930C" manufactured by
The amount of discharge was 20 picoliters per drop. This discharge was performed in a room at 25 ° C.

As the head of this ink jet device, one having one nozzle was used. Similar to the first embodiment, 70 μm, 210 μm, 280 μm, 3
Droplets of 10 columns × 10 rows were formed at each pitch of 50 μm, 420 μm, and 560 μm. The distance between the nozzle of the head and the substrate was 1 mm. As a result, sample No. 1 has a pitch of 70 μm and sample No. 2 has a pitch of 210 μm.
m, sample No. 3 has a pitch of 280 μm, sample No. 4 has a pitch of 350 μm, sample No. 5 has a pitch of 420 μm, and sample No. 6 has a pitch of 560 μm.
μm, 10 columns × 10 rows of droplets were formed on each silicon substrate.

Next, the substrate of each sample was naturally left in this state to dry the solvent from the droplets. At that time, a sample in which droplets are formed with a pitch of 350 μm or more
In Nos. 4 to 6, all the formed droplets did not move,
It was confirmed that the droplet remained at each droplet formation position. Then, after evaporation of the solvent, a thin film of Alq3 was formed at each droplet formation position. However, this Alq3 thin film was not a crystalline thin film but an amorphous thin film.

On the other hand, in sample Nos. 1 to 3 in which the droplets were formed with a pitch of 280 μm or less, the formed droplet was 1
Of the droplets of 0 column × 10 rows, all the rows of the 1st column, all the rows of the 10th column, and the droplets of the 1st and 10th rows of the 2nd to 9th columns have moved. Was confirmed. That is, the liquid droplets in the portion located on the outer periphery were moving. From the above, in this embodiment, by forming adjacent droplets with an interval of 350 μm or more, each droplet is affected by the solvent (2,3-dihydrobenzofuran) vapor evaporated from the adjacent droplet. It is considered that the partial pressure of the gas composed of 2,3-dihydrobenzofuran became uniform around each droplet as a result of not receiving the pressure. <Third Embodiment> Same as the second embodiment, 2 and 3 of Alq3
-Using a droplet composed of a dihydrobenzofuran solution, the droplet was formed by the following method. This method will be described with reference to FIG.

Using a head having one nozzle, 1-1, 2-1, 3-1, ... 30-1 in FIG. 1 (1 in FIG.
2-2 are displayed),
By discharging the above solution, 3 at a pitch of 350 μm can be obtained.
Droplets were formed in columns x 10 rows. Next, 7 to the right of 1-1
1-2 droplets are formed at a position apart by 0 μm, and sequentially 2-
The solution was discharged while moving in the order of 2, 3-2, ..., 30-2 to form droplets of 3 columns × 10 rows at a 350 μm pitch.

This process is repeated until droplets 1-6 to 30-6 are formed, and then droplets 1-7 are formed at a position 70 μm away from the bottom of 1-1, and the droplets are sequentially formed 2- 7, 3-7, ...
The droplets of 3 columns × 10 rows were formed at a pitch of 350 μm by ejecting the solution while moving in the order of 30-7. By repeating the above, 36 droplets were formed in each region of 3 columns × 10 rows divided by the boundary line indicated by the one-dot chain line in FIG. 1 at a pitch of 70 μm in both length and width. As a result, the entire substrate surface is 70μ in both length and width.
36 × 30 droplets were formed at m pitch.

Also, in this embodiment, each droplet is sequentially formed every 1 to 60 seconds by the head moving program. As a result, when forming a droplet (second droplet) at a position 70 μm away from an already formed droplet (first droplet), the first droplet is in a dry state. Was becoming. As described above, in the method of this embodiment, the droplets formed simultaneously or almost simultaneously are formed with a pitch of 350 μm that is not affected by the solvent vapor evaporated from the adjacent droplets, and the already formed droplets are formed. After it has become dry, droplets are formed at the position next to it. Therefore, for each droplet, the partial pressure of the gas composed of 2,3-dihydrobenzofuran becomes uniform around the droplet, and all the formed droplets do not move and remain at each droplet formation position. I was able to confirm that

The order of forming a plurality of droplets is such that the second droplet is formed at a position adjacent to the already formed first droplet after the drying of the first droplet. As a method of setting, for example, as in this embodiment, the substrate surface is divided into a plurality of regions, a droplet is formed in a certain region, and the next droplet is formed in another region. By
There is a method of forming droplets by allowing time to be adjacent to each other in each region.

As another example, first, the substrate is formed at the four corners, then at the center, and then at the positions between the four corners.
In consideration of the productivity, the second droplet is formed at a position adjacent to the already formed first droplet after the drying of the first droplet in such an order. There is a method of setting the formation order so that the total movement distance of the inkjet head is as small as possible.

Regarding a method in which all the liquid droplets are formed after the adjacent liquid droplets are dried and the productivity is high, the method based on the arrangement and size of the liquid droplets, the vapor pressure of the solvent to be used, etc. is used. The optimum method can be set by performing a simulation. <Fourth Embodiment> In order to form a crystalline thin film by an ink jet method, a solution forming droplets placed therein is made into a supersaturated state, and a gas containing the same component as the solvent in the vicinity of the droplets is dispersed. By controlling the pressure to a first partial pressure (for example, the same or almost the same partial pressure as the saturated vapor pressure) at which the solvent is difficult to evaporate from the solution forming the droplet, crystal nuclei are generated in the droplet, After the generation of the crystal nuclei, the partial pressure of the gas in the vicinity of the droplet is changed to a second partial pressure (for example, saturated vapor pressure) at which the crystal growth of the crystal nuclei takes precedence over the generation of further crystal nuclei. 1/10 to 1/100). Hereinafter, a method for forming a crystalline thin film by the inkjet method will be described.

According to this method of forming a crystalline thin film, first, the solution forming the droplet immediately after being placed on the substrate becomes supersaturated, so that crystal nuclei necessary for crystallization are generated in the solution. To be done. Next, the partial pressure of the gas (gas composed of the same component as the solvent) in the vicinity of the droplet is set to the first partial pressure (high partial pressure at which the solvent is difficult to evaporate from the solution forming the droplet).
From the second partial pressure (the crystal growth of already generated crystal nuclei is
Crystal growth is initiated by lowering to a lower partial pressure (which occurs preferentially over the formation of further crystal nuclei).

Therefore, in this method, for example,
By arranging the droplets in a predetermined pattern by an inkjet method, a patterned crystalline thin film can be easily formed on the substrate. Here, when the volume of the droplets placed on the substrate is extremely small, for example, 20 picoliters, as in the case where the droplet placement step is performed by, for example, an inkjet method, the gas in the vicinity of the droplets If the partial pressure of (gas consisting of the same component as the solvent of the solution forming the droplet) is low, the solvent easily evaporates from the droplet, so the concentration of the solution forming the droplet rises rapidly and the degree of supersaturation of the solution also sharply increases. As the solute becomes high, many crystal nuclei are formed and the solute is easily pulverized. On the other hand, in the method of forming a crystalline thin film, the partial pressure of the gas in the vicinity of the droplets immediately after the droplets are arranged is higher than the first partial pressure (the solvent is difficult to evaporate from the solution forming the droplets). By controlling the partial pressure), the solution that forms the droplet stabilizes in a supersaturated state with a relatively low degree of supersaturation (that is, the degree of increase in the degree of supersaturation of the solution that forms the droplet becomes moderate). Nuclei are generated).

In order to form a single crystal thin film,
After one nucleus is generated, only this nucleus is crystal-grown,
Other nucleation needs to be prevented, but if the partial pressure of the gas remains high in the vicinity of the droplet immediately after droplet placement, further nucleation will occur. On the other hand, in the method for forming a crystalline thin film, the partial pressure after the generation of the crystal nuclei is set to a low partial pressure (the first partial growth in which the crystal growth of the already-generated crystal nuclei occurs preferentially over the generation of the further crystal nuclei (second 2 partial pressure)
By lowering the value until it becomes, the crystal growth is promoted while preventing further nucleation.

Therefore, in the method of forming a crystalline thin film, a decrease in the partial pressure from the first partial pressure to the second partial pressure is caused by a small number (ideally one) of crystal nuclei in the solution. By rapidly performing immediately after the generation, for example, from the first partial pressure that is the same or almost the same partial pressure as the saturated vapor pressure, 1.3
By lowering to a second partial pressure of Pa (10 ^-2 torr) in 1 to 10 seconds, the degree of supersaturation of a solution forming a droplet is rapidly increased to obtain a single crystal crystalline thin film. be able to.

In the method of forming a crystalline thin film, as a partial pressure control method for the first partial pressure, a method of adjusting the discharge interval of the droplets, a method of adjusting the discharge amount of the solution, the liquid Before the droplet arrangement step, a method of adjusting the partial pressure of the gas at the position where the droplet is arranged can be mentioned. In the method of forming a crystalline thin film, as the partial pressure reducing method, a method of decompressing an atmosphere in the vicinity of the droplet, a method of increasing a temperature in the vicinity of the droplet, an atmosphere of the vicinity of the droplet in an inert gas atmosphere The method of substituting In the method, there is a case where the partial pressure of the gas does not decrease (such as a case where a series of steps is performed in a closed space), but even in that case, the saturated vapor pressure increases due to the temperature increase, and the solvent of the droplets becomes Since it is in a state of being easily vaporized, the same action as that in the case where the partial pressure of the gas is lowered (the supersaturation degree of the solution forming the droplet is rapidly increased) can be obtained.

Further, in the method for forming a crystalline thin film, as the solution, (1) a solution containing an amount of a thin film forming material that is saturated when ejected, or (2) a saturated concentration when ejected. It is preferable to use a solution containing the thin film forming material in an amount of 1/10 or more and less than the saturation concentration, or (3) a solution containing an amount of the thin film forming material in a supersaturated state at the time of ejection. . As a result, the solution forming the droplets arranged on the substrate is likely to be in a supersaturated state immediately after being ejected, so that the formation of crystal nuclei is surely performed.

When the droplets of the solution are arranged on the substrate by the method for forming the crystalline thin film, the method of the present invention is adopted to prevent the droplets from moving, thereby making it possible to prevent the movement of the droplets on the substrate. A crystalline thin film can be formed at a predetermined position. The fourth embodiment is an embodiment to which the method of the present invention is applied when performing the method for forming the crystalline thin film.

A thin film forming apparatus shown in FIG. 2 was used to form a thin film on the silicon substrate. This device
It is composed of a closed container 1, an XY stage 2 installed in the closed container 1, a head 3 of an inkjet device, a pump 6 for depressurizing the inside of the closed container 1 and a pipe 7. The head 3 is fixed to the upper part of the closed container 1, and the solution is supplied into the head 3 from the outside. Head 3 and XY stage 2
Are arranged at positions facing each other. Pump 6
The pipe 7 for use is connected to the bottom of the closed container 1.

First, the inside of the closed container (closed space) 1 is set to 2
Terthiophene (thin film forming material) while maintaining at 5 ℃
Was dissolved in dodecylbenzene (solvent) to a concentration of 0.1% by weight, and the solution was dissolved by the same method as in the third embodiment.
It was ejected onto the silicon substrate by an inkjet method. However, in the third embodiment, the arrangement position of the liquid droplets is set by moving the head 3, but in this embodiment, XY is arranged.
It was performed by moving the stage 2.

The saturated concentration of terthiophene with respect to dodecylbenzene at 25 ° C. (temperature at the time of discharging the solution) is 1.0% by weight. Therefore, this terthiophene solution has a saturation concentration of 1/10 when ejected. Simultaneously with the completion of the droplet formation, the decompression pump 6 was operated to decompress the closed space to 1.3 Pa (10 ^-2 torr), and this state was maintained for 6 hours. On the silicon substrate 1 taken out from the sealed space after 6 hours, a substantially rectangular terthiophene thin film (thickness: 50 μm) of 20 μm × 30 μm was formed in a substantially single crystal state at each position where each droplet was formed. Was there. The terthiophene single crystal thin film is a functional thin film that can be suitably used as an organic semiconductor film.

In this embodiment, since the concentration of the solution at the time of ejection is 1/10 of the saturation concentration, the solution forming droplets is likely to be in a supersaturated state immediately after being placed on the substrate. Also, 1
Since the discharge amount per droplet is 20 picoliters and the droplets are formed with a pitch of 70 μm, the partial pressure of the gas composed of dodecylbenzene (the same component as the solvent) around the droplets becomes droplets. The high partial pressure makes it difficult for 2,3-dihydrobenzofuran (solvent) to evaporate from the solution. From these facts, it is considered that a small number of nuclei were formed because the solution in the form of droplets was stable in a supersaturated state with a relatively low degree of supersaturation.

Further, by starting the pressure reduction in the closed space at the same time when the formation of the droplets is completed, the partial pressure of the solvent vapor in the vicinity of the droplets is drastically reduced when a small number of crystal nuclei are formed, The degree of supersaturation of the solution in the form of droplets increases rapidly, and crystal growth occurs preferentially over the formation of further crystal nuclei. By maintaining this reduced pressure state for 6 hours, crystal growth is promoted. It is thought that it was done.

Further, since the low vapor pressure solvent is used as the solvent, all the formed droplets do not move and remain at each droplet forming position, and the droplet forming position (predetermined position) on the substrate. It is considered that a crystalline thin film was formed on the. Although the thin film forming apparatus shown in FIG. 2 is used in the present embodiment, a partition plate for separating the head 3 of the thin film forming apparatus of FIG. You may use what was provided. By providing this partition plate, it is possible to depressurize only the stage installation side without depressurizing the head installation side inside the closed container 1. <Fifth Embodiment> Like the fourth embodiment, the fifth embodiment is also an embodiment in which the method of the present invention is applied when performing the method for forming the crystalline thin film.

A solution of 4-amino-p-terphenyl having the structure represented by the chemical formula (5) (material for forming a thin film) is dissolved in dimethylformamide (solvent) to a concentration of 1.0% by weight. Got 4-Amino-p to dimethylformamide at 25 ° C. (temperature at the time of solution discharge)
The saturation concentration of terphenyl is 1.0% by weight. Therefore, in this solution, 4-amino-p-terphenyl becomes saturated upon ejection.

Droplets were formed in the same manner as in the fourth embodiment except that this solution was used. Simultaneously with the completion of the droplet formation, the decompression pump 6 was operated to decompress the closed space to 1.3 Pa (10 ^-2 torr), and this state was maintained for 6 hours. The silicon substrate 1 taken out from the closed space after 6 hours had a thickness of 20 μm at each position where each droplet was formed.
An approximately rectangular 4-amino-p-terphenyl thin film (thickness 50 μm) of 30 μm was formed in a substantially single crystal state. The 4-amino-p-terphenyl crystalline thin film is a functional thin film that can be suitably used as a semiconductor film for various electronic devices.

In this embodiment, since the solution becomes saturated at the time of ejection, the solution forming droplets immediately after being placed on the substrate is likely to become supersaturated, and due to the same operation as the fourth embodiment, It is thought that a small number of nuclei were formed. Further, it is considered that the crystal growth was also promoted by the same action as in the fourth embodiment. <Sixth Embodiment> Similar to the fourth embodiment, the sixth embodiment is an embodiment in which the method of the present invention is applied when the method of forming the crystalline thin film is performed.

2,2 ′ of the structure represented by the chemical formula (6):
Dissolve 5 ', 2 "-terthiophene-5,5" -dicarboxaldehyde (terthiophene derivative, thin film forming material) in dimethylformamide (solvent) to a concentration of 1.0% by weight. A solution was obtained. The saturated concentration of the above derivative with respect to dimethylformamide at 25 ° C. (temperature at the time of discharging the solution) is 1.0% by weight. Therefore, in this solution, the above-mentioned derivative becomes saturated when ejected.

Droplets were formed in the same manner as in the fourth embodiment except that this solution was used. Simultaneously with the completion of the droplet formation, the decompression pump 6 was operated to decompress the closed space to 1.3 Pa (10 ^-2 torr), and this state was maintained for 6 hours. The silicon substrate 1 taken out from the closed space after 6 hours had a thickness of 20 μm at each position where each droplet was formed.
× 30μm approximately rectangular 2,2 ': 5', 2 "-terthiophene-
5,5 "-dicarboxaldehyde thin film (thickness 50 μm)
However, it was formed in a substantially single crystal state. The 2,2 ′: 5 ′, 2 ″ -terthiophene-5,5 ″ -dicarboxaldehyde crystalline thin film is a functional thin film that can be suitably used as a semiconductor film for various electronic devices.

In this embodiment, since the solution becomes saturated at the time of ejection, the solution forming droplets immediately after being placed on the substrate is likely to become supersaturated, and due to the same operation as in the fourth embodiment, It is thought that a small number of nuclei were formed. Further, it is considered that the crystal growth was also promoted by the same action as in the fourth embodiment. The fourth
-In the sixth embodiment, the first partial pressure is rapidly reduced to the second partial pressure by starting the pressure reduction in the closed space at the same time when the droplet formation is completed, and the solution forming the droplet is supersaturated. The crystallinity thin film of single crystal is obtained by rapidly increasing the degree,
The timing of starting the depressurization is not limited to the same time as the end of the droplet formation, and may be performed at an appropriate timing depending on other conditions and the like.

The crystalline thin film formed by the forming method of the present invention is suitably used as a semiconductor film for various electronic devices (transistors, diodes, capacitors, light emitting layers in organic EL devices, hole injection / transport layers, etc.). it can.
A liquid crystal display device, an organic EL display device, or the like can be given as a display device including an electronic device on which a thin film is formed by the method of the present invention. These display devices are, for example,
It can be applied to various electronic devices shown in FIG.

FIG. 3A is a perspective view showing an example of a mobile phone. In FIG. 3A, reference numeral 600 denotes a mobile phone main body, and reference numeral 601 denotes a display unit using the display device. FIG. 3B is a perspective view showing an example of a portable information processing device such as a word processor and a personal computer.
In FIG. 3B, reference numeral 700 is an information processing apparatus, reference numeral 701 is an input unit such as a keyboard, reference numeral 703 is the information processing apparatus main body, and reference numeral 702 is a display unit using the display device.

FIG. 3C is a perspective view showing an example of a wristwatch type electronic device. In FIG. 3C, reference numeral 800
Indicates a watch body, and reference numeral 801 indicates a display unit using the display device. Each of the electronic devices shown in FIGS. 3A to 3C has a display unit including a display device including an electronic device using the crystalline thin film formed by the method of the embodiment as a semiconductor film. There is a feature of the thin film forming method of the present invention. Therefore, according to the thin film forming method of the present invention, the manufacturing method of these electronic devices can be facilitated.

[0063]

As described above, according to the method of the present invention, a thin film of a low molecular weight compound can be formed at a predetermined position on a substrate. Further, by applying the method of the present invention to a method of forming a patterned crystalline thin film by an inkjet method, the crystalline thin film is likely to be stably formed at a predetermined position on the substrate according to the pattern. As a result, the patterned crystalline thin film can be easily formed.

[Brief description of drawings]

FIG. 1 is a plan view illustrating a droplet forming order performed in a third embodiment.

FIG. 2 is a schematic configuration diagram showing a thin film forming apparatus used in fourth to sixth embodiments.

FIG. 3 is a perspective view showing an example of an electronic apparatus having a display device including an electronic device on which a thin film is formed by the method of the present invention.

[Explanation of symbols]

1 ... Airtight container, 2 ... XY stage, 3 ... Head (inkjet device), 6 ... Pump, 7 ... Piping, 1-1 to 1
-36 ... Droplet, 2-1 and 2-2 ... Droplet, 3-1 and 3-2
... Droplets, 4-1 and 4-2 ... Droplets, 5-1 and 5-2 ... Droplets, 6-1, 6-2 ... Droplets, 7-1, 7-2 ... Droplets, 8
-1,8-2 ... Droplet, 9-1, 9-2 ... Droplet, 10-
1, 10-2 ... Droplet, 11-1, 11-2 ... Droplet, 12
-1,12-2 ... Droplet, 600 ... Mobile phone main body, 601
Display unit 700 Information processing device 701 Input unit 7
03 ... Information processing apparatus main body, 702 ... Display unit, 800 ... Clock body, 801, ... Display unit.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H05B 33/14 H01L 29/28 F term (reference) 3K007 AB18 BA06 DB03 FA01 4D075 AC06 AC09 AC88 AE02 BB24Y BB24Z CA22 DA06 DB13 DB14 DC19 DC22 DC24 EA07 EB44 EB47 EC07 EC30 EC51 5F053 AA00 AA48 BB60 DD20 FF01 GG01 HH01 LL10 RR04 RR11 5G435 AA17 BB05 CC09 HH20 KK05 KK10

Claims (6)

[Claims] 1. A solution in which a thin film forming material is dissolved in a solvent.
By ejecting a plurality of droplets of the solution onto the substrate.
Individually arranged and by evaporating the solvent from each droplet
In the method of forming a thin film on a substrate, As the solvent, the vapor pressure at the time of the discharge is 1.3 ×
10^-3Pa (1 x 10 ^-FivemmHg) or lower low vapor pressure
A method for forming a thin film, which comprises using a solvent. 2. A plurality of droplets of the solution are arranged on a substrate by ejecting a solution in which a thin film forming material is dissolved in a solvent, and the solvent is evaporated from each droplet to deposit on the substrate. In the method for forming a thin film, after forming the first droplet, the second droplet is formed at a position separated from the formation position of the first droplet by a predetermined distance. Method. 3. A plurality of droplets of the solution are arranged on a substrate by ejecting a solution in which a thin film forming material is dissolved in a solvent, and the solvent is evaporated from each droplet to deposit on the substrate. A method of forming a thin film, comprising forming the second droplet at a position adjacent to the first droplet after drying the first droplet. 4. The thin film forming method according to claim 1, wherein the thin film forming material is oligophenylene or a derivative thereof. 5. The method for forming a thin film according to claim 1, wherein the thin film forming material is oligothiophene or a derivative thereof. 6. A method for forming an electronic device, comprising the step of forming a thin film by the method according to claim 1.