JP2001327912A - Method for forming thin film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the efficiency of a coating liquid to be used by improving a process in which the coating liquid is stuck on the surface of a substrate in spin coating. SOLUTION: An apparatus for forming a thin film has a spin unit 10 which holds the substrate 1 and rotates it at a desired rotational speed and an ink-jet heat 20 located above the unit 10. The heat 20 has small-diameter nozzles 21, which are arranged at constant intervals in the radium direction of the substrate. In the coating liquid sticking process, while the substrate is rotated slowly, liquid drops 22 are discharged from the nozzles 21 in required timing to be stuck on the surface of the substrate in an optimum pattern. The substrate is rotated at a high speed in a thin film forming process, the adherent liquid drops 23 is spread on the surface of the substrate by centrifugal force, and the excess coating liquid is scattered to be removed. An ink-jet heat 20 is preferably piezo-type which can discharge a liquid with viscosity as high as 10 Pa.s.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spin coating (rotation coating) thin film forming method, and more particularly, to a method in which a liquid is dropped from a micro-diameter nozzle onto a substrate surface and the droplet is rotated at a high speed. The present invention relates to a method of forming a thin film by spreading the above.

[0002]

2. Description of the Related Art Conventionally, sputtering, CVD, printing, roll coating, spin coating, and the like have been widely used as a method of forming a thin film on a substrate surface or the like. Widely used for anti-reflection coating, protective coating, developer coating, etc.

[0003] Regarding the conventional general spin coating method,
This will be described with reference to FIG. FIG. 5A is an explanatory view of a structure of a spin coating apparatus (spin coater) and a coating liquid adhering step, and FIG. 5B is an explanatory view of a spin step (thin film forming step). In FIG. 5A, the spin unit 101 is
A rotating shaft 102 and a substrate holding member 103 integral therewith are provided. A coating nozzle 110 for supplying liquid droplets is provided immediately above the center of the substrate holding member 103. The substrate holding member 103 is rotatable in the horizontal direction by the rotation of the rotation shaft 102.

In the spin coater thus configured, as shown in FIG. 5A, a required amount of a coating liquid 111 is dropped from a coating nozzle 110 onto a central portion of a substrate 120 held by a substrate holding member 103. . Reference numeral 112 denotes an attached droplet on the substrate 120. Next, as shown in FIG. 5B, the substrate 120 is rotated at a required rotation speed by rotation of the rotation shaft 102 (thin film formation rotation), and the attached droplets 112 are spread on the substrate 120 by the centrifugal force and applied. The thin film 113 is formed by reducing the thickness of the liquid 111. The thickness of the thin film 113 is 100 μm or less, generally 10 μm.
The following is assumed. In FIG. 5B, reference numeral 114 denotes excess liquid which is shaken off by the centrifugal force and scattered.

What is important in the spin coating shown in FIG. 5 is that when a thin film having a desired film thickness is formed over a desired range on the substrate surface, the amount of liquid used, that is, the amount of the coating liquid dropped from the coating nozzle 110 onto the substrate 120 is reduced. The aim is to minimize the amount used. However, in reality, only a small part of the coating liquid 111 dropped on the substrate 120 is effectively used for forming a thin film.
% Or more.

In the spin coating shown in FIG. 5, as described above, the effective utilization rate of the dripping coating liquid is extremely low because, as shown in FIG. This is because it is limited and spreads in that direction due to centrifugal force, and the amount of wasted liquid increases when it is spread over the entire surface of the substrate 120.

Therefore, various spin coating apparatus manufacturers have proposed various spin coating methods capable of reducing the amount of liquid used (improving the use efficiency of a coating liquid). One of them is to modify the surface condition of the substrate. In this method, a chemical solution for modifying the surface state is applied to the substrate prior to the application of the liquid to improve the wettability of the substrate surface. This improves the adhesion rate of the coating liquid to the substrate surface, thereby reducing the amount of liquid scattered due to the rotation of the substrate.

The other is a two-stage rotation method. As shown in FIG. 7, by controlling the above-described thin-film formation rotation in two stages, the physical specific direction can be more diversified. Thus, the use efficiency of the coating liquid is improved. However, these methods have limitations in improving the use efficiency, and are not ideal methods.

Japanese Patent Application Laid-Open No. Hei 8-196983 proposes a method for reducing the amount of liquid used by applying a liquid to the substrate surface using an ink jet head. However, this method uses a nozzle (nozzle hole:
After applying the coating liquid 212 from the liquid discharge port 211 onto the entire surface of the substrate 120, the coating liquid is shaken off at high speed to form a thin film, which is improved compared to the conventional method. Since the liquid is applied to the entire surface of the substrate 120, the effect of reducing the amount of liquid used is limited. In FIG. 8, reference numeral 201 denotes a spin unit, and reference numeral 213 denotes an attached droplet.

[0010]

SUMMARY OF THE INVENTION The present invention is intended to drastically solve the above-mentioned problems in the conventional spin coating method, and an object of the present invention is to improve a process of applying a coating solution to a substrate surface. Another object of the present invention is to provide a method for forming a thin film, which can significantly improve the use efficiency of a coating solution.

[0011]

According to the thin film forming method of the present invention, a substrate and an ink jet head having a plurality of minute diameter nozzles for discharging a liquid toward the surface of the substrate are relatively moved. A step of depositing the droplets on the substrate surface in an optimal pattern, and rotating the substrate on which the droplets are deposited at a required rotation speed, so that the droplets deposited in the optimal pattern on the substrate surface And forming a thin film having a uniform film thickness, and shaking off and scattering excess liquid.

In the present invention, "adhering droplets on the substrate surface in an optimum pattern" means that after the droplets are adhered on the substrate surface, the adhering liquid is deposited on the substrate surface by centrifugal force caused by high-speed rotation of the substrate. When a thin film (coating liquid film) having a desired uniform thickness is formed in a required area on the substrate surface, the liquid adhered to the substrate surface can be effectively used for forming the thin film (scattered from the substrate). This means that the liquid is attached to the substrate surface in a pattern that can minimize the ratio of the excess liquid to be applied.

In the method of forming a thin film according to the present invention, the method for adhering droplets on the substrate surface in an optimal pattern includes, for example, (1) providing one ink jet head and performing a liquid discharging operation of a plurality of micro-diameter nozzles. And (2) providing a plurality of ink jet heads and independently controlling the liquid ejection operation of these ink jet heads to control the surface of the substrate. A method of forming a required optimal pattern in a short time by attaching droplets to the liquid in an optimal pattern.

As the ink-jet head, it is desirable to use a piezo-type ink-jet head which discharges liquid using ceramics (piezo elements) which are deformed when a voltage is applied, which is generally known as a drop-on-demand method. This makes it possible to discharge a relatively high-viscosity liquid more reliably, stably, and more accurately than other inkjet heads, and has a viscosity of 10 Pa · s.
It can be used effectively for discharging liquids up to (100 cp).

In the present invention, in order to set conditions for "adhering droplets on the substrate surface in an optimum pattern", the properties of the liquid to be used and the physical properties of the substrate surface (including the surface condition of the substrate) It is extremely effective to use a simulation such as liquid analysis taking into account the above.

In the case where a thin film is formed on the entire surface of the substrate, the step of depositing the droplet on the surface of the substrate includes, in a central portion of the substrate, a circular droplet deposition pattern concentric with the center of the substrate;
On its outer peripheral side, a plurality of circular droplet attachment patterns concentric with the circular pattern are formed with the same thickness, and the area of the circular pattern and the area of the circular pattern are different from those of the circular pattern. It is preferable to minimize the area and to gradually increase the area of the annular pattern from the inner peripheral portion to the outer peripheral portion. By doing so, the droplets can be attached to the substrate surface in an optimal pattern. When a thin film is formed on the entire surface of the substrate provided with the center hole, a plurality of annular droplet attachment patterns are formed concentrically around the center of the substrate and at the same thickness as each other. It is preferable to gradually increase the area of the annular pattern from the inner peripheral portion to the outer peripheral portion of the substrate.

As described above, according to the thin film forming method of the present invention, after the coating liquid is applied to the surface of the substrate from the nozzle of the ink jet head, the excess coating liquid is shaken off and dispersed by high-speed rotation of the substrate to form a uniform film thickness. In spin coating for forming a thin film of the above, the use efficiency of the coating liquid can be greatly improved.

The following can be used as an apparatus for carrying out the thin film forming method of the present invention. That is, this thin film forming apparatus has a substrate rotating means for holding and rotating the substrate in the horizontal direction, and a plurality of micro-diameter nozzles for discharging the liquid, and the liquid is dropped on the surface of the substrate held by the substrate rotating means. An ink jet head, a substrate rotation control means for controlling the operation of the substrate rotation means, and a thin film forming apparatus comprising a head control means for controlling the operation of the inkjet head, wherein the substrate rotation control means, A low-speed rotation that rotates the substrate at a rotation speed at which the droplets adhered to the substrate surface do not spread by centrifugal force, and the droplets adhered to the substrate surface spread by centrifugal force and excess liquid is shaken off from the substrate and scattered It can be switched to high speed rotation.

As a matter of course, this thin film forming apparatus
It is necessary to configure so as to be able to “adhere droplets on the substrate surface in an optimal pattern”. For example, it is preferable that one ink jet head is provided, and the liquid discharge operation of the plurality of micro-diameter nozzles is independently controlled. In this case, moving means for moving the ink jet head by a small distance in the horizontal direction and control means for controlling the operation of the moving means are provided, and the control means moves the ink jet head in the horizontal direction in a predetermined manner. It is preferable that the droplets are formed, and the droplets can be more easily and easily adhered to the substrate surface in an optimum pattern.

As another example of the thin film forming apparatus, a plurality of ink jet heads are provided, and by independently controlling the liquid discharge operation of these ink jet heads, liquid droplets can be deposited on the substrate surface in an optimum pattern. What was done. Further, as the ink jet head, a piezo type ink jet head is preferable for the above-mentioned reason.

[0021]

Embodiments of the present invention will be described with reference to the drawings. First Embodiment FIG. 1 is a schematic front view showing the structure of a main part of a thin film forming apparatus (spin coater) and a process of applying a coating liquid to a substrate surface using the apparatus. In this thin film forming apparatus, an ink jet head 20 having a plurality of micro-diameter nozzles 21 is provided above a holding member 12 for holding a substrate so as to be movable in a horizontal direction by head moving means (not shown). Further, a head movement control means (not shown) for controlling the operation of the head movement means and a nozzle control means (not shown) for controlling the liquid discharge operation of the nozzle 21 are provided. The ink jet head 20 uses the electric signal from the nozzle control means to control the nozzle 2
1 to discharge droplets (coating liquid) 22 toward the surface of the substrate 1. Also, a plurality of nozzles 21, 21,.
Are arranged in a predetermined pattern, that is, at regular intervals (generally 40 μm to 300 μm) in the radial direction of the substrate 1.

A spin unit 10 serving as a substrate rotating means for holding and rotating the substrate 1 in the horizontal direction includes a rotating shaft 1.
1 and the holding member 12 integrated therewith. The rotation shaft 11 has a substrate rotation control means (not shown) for controlling the rotation speed. The substrate rotation control means includes a low-speed rotation for rotating the substrate 1 at a rotation speed at which the droplets adhered to the substrate surface do not spread due to centrifugal force, a method for spreading the droplets adhered to the substrate surface by centrifugal force, and Can be switched to a high-speed rotation enough to shake off the substrate.

In the coating liquid application step using the above-mentioned thin film forming apparatus, the nozzle control means ejects the liquid droplets 22 from the nozzles 21 at a required timing, thereby adhering the liquid droplets to the surface of the substrate 1 in an optimum pattern. In FIG. 1, reference numeral 23 denotes an attached droplet. More specifically, while the substrate 1 is rotated at a required rotation speed, the coating liquid 22 is intermittently adhered to the surface of the substrate in the form of liquid droplets from the nozzle 21 at a specific frequency. In this case, the substrate rotation speed and the ejection frequency of the application liquid from the nozzle 21 may be any as long as the application liquid droplets can adhere to the substrate surface in an optimal pattern. Also, when the arrangement pitch of the plurality of nozzles 21 in the inkjet head 20 is wider than the arrangement pitch of the required optimum pattern, while sequentially moving the inkjet head 20 in the radial direction of the substrate 1 by the head moving means, The substrate 1 is rotated at a plurality of predetermined rotational speeds, so that the applied liquid droplets adhere to the surface of the substrate 1 in an optimal pattern.

After confirming that the applied droplets adhere to the substrate surface in an optimum pattern, the substrate 1 is rotated at a predetermined rotation speed, and the surplus application liquid is shaken off to form a required thin film. As described above, by forming a pattern of very small droplets on the substrate by the inkjet head 20, a thin film having a uniform thickness can be formed, and the amount (proportion) of the surplus coating solution to be shaken and scattered is greatly increased. Can be reduced.

Second Embodiment FIG. 2 is a schematic front view showing a main structure of a thin film forming apparatus and a step of applying a coating liquid to a substrate surface by using the apparatus. The ink jet system is roughly classified into a continuous system in which continuously ejected ink is selectively landed on a surface to be coated, and a drop-on-demand system in which ink is selectively ejected. In the past, the continuous system was rather popular, but in recent years, the on-demand system having technically advanced characteristics has been overwhelmingly used.

This drop-on-demand type ink jet head discharges ink using a bubble method in which ink is rapidly heated and ink is discharged by generated bubbles, and a ceramic (piezo element) which deforms when a voltage is applied. Piezo method. Among them, the bubble type has a narrow range of use because the liquid used is limited due to its characteristics.

On the other hand, the piezo-type ink jet head has a limited use in the viscosity of the liquid, but there are many types of liquids to be applied, and means for solving the problem of discharging a liquid having a high viscosity have been developed. 10 Pa · s (10
It is possible to discharge liquid up to 0 cp).

In FIG. 2, reference numeral 30 denotes a spin unit,
Reference numeral 31 denotes a rotation shaft, and reference numeral 32 denotes a holding member for holding a substrate. The structure of the spin unit 30 is the same as that of the spin unit 10 in FIG. On the other hand, a liquid chamber 41 for storing a coating liquid 51 is formed inside the inkjet head 40, and this liquid chamber 41 is connected to a coating liquid supply unit (not shown) via a coating liquid supply port 42. Inkjet head 4
A large number of nozzles 43 are formed in a lower part of 0. A piezoelectric element 44 for discharging the coating liquid in the liquid chamber 41 from the nozzle 43 and a driver IC 45 for operating the piezoelectric element 44 are provided above the ink jet head 40 (the back of the liquid chamber 41). Has been deployed.

A drive circuit 61 having a pulse generation circuit and a CPU is connected to the driver IC 45 and a rotation position detection circuit 62 for detecting the rotation position of the substrate 1 on the holding member 32. Position detection circuit 62
Is connected to the rotating shaft 31. Further, head moving means (not shown) for moving the inkjet head 40 in the horizontal direction, that is, along the surface of the substrate 1, and head movement controlling means (not shown) for controlling the operation of the head moving means.
Are provided.

The operation of the spin coater thus configured will be described below. The basic method of forming a thin film is the same as that of the spin coater shown in FIG. First, the substrate 1 is rotated at a required rotation speed. The driver IC 45 is driven by the drive circuit 61 based on the position detection information from the rotational position detection circuit 62.
The driving voltage is applied from the driver IC 45 to the piezoelectric element 44, and the coating liquid 51 is discharged from the nozzle 43 and adheres to the surface of the substrate 1. In FIG.
Numeral 2 is an attached droplet on the substrate surface.

In the above-mentioned coating liquid application step, a desired optimum liquid droplet application pattern is obtained by independently controlling the liquid droplet ejection operation of the nozzle 43 of the ink jet head 40.
It can be formed more easily. In this case, the application can be performed while the inkjet head 40 is moved in a predetermined manner by the head moving means, or the application liquid can be discharged while the position of the inkjet head 40 is fixed. It is also very effective to obtain an optimal coating pattern by using a scientific simulation such as fluid analysis in accordance with the characteristics of the liquid used and the physical properties of the substrate surface. The distance between the inkjet head 40 and the surface of the substrate is generally set to 1 mm to 1.5 mm.
mm and a high landing accuracy of about ± 10 μm can be obtained.

Then, after confirming that an optimum droplet attachment pattern has been formed on the substrate surface, the substrate 1 is rotated at a predetermined rotation speed, and the excess coating solution is shaken off and dispersed.
Form the required thin film. As described above, by forming an application pattern of very small droplets on the substrate by the inkjet head 40, a thin film having a uniform thickness can be formed, and the ratio of the excess application liquid to be shaken and scattered can be significantly reduced. Can be reduced.

Third Embodiment FIG. 3 is a schematic front view showing a structure of a main part of a thin film forming apparatus and a process of applying a coating liquid to a substrate surface using the apparatus. FIG.
Reference numeral 70 denotes a spin unit having a rotation shaft 71 and a holding member 72 for holding the substrate 1, and reference numerals 80a, 80
0b and 80c are ink jet heads. The number of ink jet heads can be two or four or more.

The operation of the spin coater thus configured will be described below. The basic method of forming a thin film is the same as that of the spin coater shown in FIG. While rotating the substrate 1 at a required rotation speed, the plurality of inkjet heads 80
The coating liquid 90 is intermittently adhered to the surface of the substrate 1 at a specific frequency in the form of droplets from the nozzles 83a to 80c. In this case, the substrate rotation speed and the liquid ejection frequency from the nozzle 83 may be any condition that allows an optimal pattern of the applied droplets to be formed on the substrate surface. By operating a plurality of inkjet heads as described above, In addition, the optimum pattern application can be realized in a short time. In FIG. 3, reference numeral 90a denotes an attached droplet.

After confirming that the optimum droplet deposition pattern has been formed on the substrate, the substrate 1 is rotated at a predetermined rotation speed, and the surplus coating solution is shaken off to form a required thin film. In this way, a thin film having a uniform thickness is formed in a desired region on the substrate surface by discharging the fine droplets from the plurality of inkjet heads toward the substrate and forming the optimal adhesion pattern of the coating liquid on the substrate surface. Can do it,
The ratio of the surplus coating liquid to be shaken and scattered can be greatly reduced.

FIG. 4 shows a state in which droplets are deposited on the substrate surface in an optimal pattern when a thin film is formed on the entire surface of the substrate in the first to third embodiments.
(A) is a schematic plan view, (b) is a sectional view thereof. In this droplet attachment pattern, a circular droplet attachment pattern 91 is formed at the center of the substrate, and annular droplet attachment patterns 92 and 93 concentric with the circular pattern 91 are formed on the outer peripheral side. Further, the thicknesses of these droplet attachment patterns are equal to each other, and the area S9 of these patterns
1, S92, and S93 have a magnitude relationship of S91 <S92 <S
93. That is, the volume of the adhesion liquid forming the circular pattern 91 is V91, and the volumes of the adhesion liquid forming the annular droplet adhesion patterns 92 and 93 are V9.
2, V93, the magnitude relationship between V91, V92, and V93 is V91 <V92 <V93.

[0037]

According to the first aspect of the present invention, there is provided a method of forming a thin film on a substrate, wherein the droplet is deposited on the substrate surface in an optimum pattern, and the droplet deposited on the substrate is spread on the substrate surface to form a uniform film. And a step of shaking off and scattering excess liquid as well as forming a thin film. For this reason, according to this thin film forming method, when a thin film having a uniform thickness is formed in a desired region on the substrate surface, the proportion of the application liquid adhered to the substrate surface that scatters from the substrate surface is significantly reduced, The use efficiency of the coating liquid can be greatly improved as compared with the conventional technology.

According to the thin film forming method of the present invention, one ink jet head for attaching a droplet to the substrate surface is provided, and the liquid discharging operation of a plurality of small diameter nozzles provided on the ink jet head is independently performed. Since the control is performed, droplets can be easily attached to the substrate surface in an optimal pattern.

In the thin film forming method according to the third aspect, since a plurality of ink jet heads are provided and the liquid discharge operation of these ink jet heads is independently controlled, the droplets can be easily formed on the substrate surface in an optimum pattern. Can be attached.

In the thin film forming method according to the fourth aspect, since a piezo type ink jet head is used as the ink jet head, a liquid having a viscosity in the range of several Pa · s to 10 Pa · s can be stabilized. Can be ejected. In the thin film forming method according to the fifth aspect, since a liquid having a viscosity of up to 10 Pa · s is ejected from the ink jet head, a high-viscosity liquid such as a resist material, a developing solution, and a protective film is applied. It is possible to

In the thin film forming method according to the sixth aspect, since the optimum pattern is set by using a simulation of liquid analysis in consideration of the characteristics of the liquid and the physical properties of the substrate surface, the pattern setting can be performed with high precision and efficiency. Can be done

According to the thin film forming method of the present invention, when a thin film is formed on the entire surface of a substrate, a circular droplet attaching pattern and an annular droplet attaching pattern are formed in a predetermined manner. Therefore, an optimum droplet deposition pattern on the substrate surface can be formed with a simple operation with good reproducibility.

[Brief description of the drawings]

FIG. 1 is a schematic front view showing a main structure of a thin film forming apparatus and a step of applying a coating liquid to a substrate surface according to a first embodiment of the present invention.

FIG. 2 is a schematic front view showing a main part structure of a thin film forming apparatus and a step of applying a coating liquid to a substrate surface according to a second embodiment of the present invention.

FIG. 3 is a schematic front view showing a main part structure of a thin film forming apparatus and a step of applying a coating liquid to a substrate surface according to a third embodiment of the present invention.

FIGS. 4A and 4B show a state in which liquid droplets are adhered to the entire surface of a substrate in an optimum pattern according to the present invention, wherein FIG. 4A is a schematic plan view and FIG.

FIG. 5 relates to a conventional general spin coating technique,
FIG. 2A is a schematic front view showing a main part structure of a spin coating apparatus and a step of applying a coating liquid to a substrate surface, and FIG. 2B is a schematic front view showing a spin coating step (thin film forming step).

FIG. 6 is a diagram illustrating a problem of the spin coating method of FIG. 5;

FIG. 7 is an explanatory view showing a spin coating method according to another conventional example and its problems.

FIG. 8 is a schematic front view showing a main structure of a spin coating apparatus according to still another conventional example and a step of applying a coating liquid to a substrate surface.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Substrate, 10 ... Spin unit, 11 ... Rotation axis, 12
... holding member, 20 ... inkjet head, 21 ... nozzle, 22 ... droplet (coating liquid), 23 ... attached droplet, 30 ... spin unit, 31 ... rotating shaft, 32 ... holding member, 40 ...
Ink-jet head, 41 ... liquid chamber, 42 ... coating liquid supply port, 43 ... nozzle, 44 ... piezoelectric element, 45 ... driver IC, 51 ... coating liquid, 52 ... adhered droplet, 61 ... driving circuit, 62 ... rotational position detection Circuit, 70 ... spin unit,
71: rotating shaft, 72: holding member, 80a to 80c: inkjet head, 83: nozzle, 90: coating liquid, 90
a: attached droplets, 91: circular droplet attached pattern, 92,
93: annular droplet adhesion pattern, 101: spin unit, 102: rotation axis, 103: substrate holding member, 110
... Coating nozzle, 111 ... Coating liquid, 112 ... Adhered droplet, 1
13 ... thin film, 114 ... surplus liquid, 120 ... substrate, 201 ...
Spin unit, 210: inkjet head, 21
1. Nozzle (nozzle hole: liquid discharge port), 212: coating liquid, 213: attached droplet.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G03F 7/30 502 G03F 7/30 502 5F046 H01L 21/027 H01L 21/30 564D

Claims (7)

[Claims] 1. An ink jet head having a plurality of micro-diameter nozzles for discharging a liquid toward a surface of a substrate is relatively moved, so that droplets are attached to the surface of the substrate in an optimal pattern. And rotating the substrate on which the droplets are deposited at a required rotation speed, thereby spreading the droplets deposited in the optimum pattern on the substrate surface to form a thin film having a uniform thickness. And a step of shaking off and scattering excess liquid. 2. An ink jet head is provided,
2. The thin film forming method according to claim 1, wherein liquid droplets are adhered to the substrate surface in an optimal pattern by independently controlling liquid discharge operations of a plurality of minute diameter nozzles. 3. The method according to claim 1, wherein a plurality of the ink jet heads are provided, and the liquid ejecting operations of the ink jet heads are independently controlled so that the liquid droplets adhere to the substrate surface in an optimum pattern. The method for forming a thin film according to the above. 4. The inkjet head according to claim 1, wherein said inkjet head is a piezo type inkjet head.
3. The method for forming a thin film according to item 1. 5. The method according to claim 1, wherein the liquid has a viscosity of 10 Pa · s or less. 6. The method according to claim 1, wherein the optimal pattern is set by using a simulation of a liquid analysis in consideration of characteristics of the liquid and physical properties of the substrate surface.
3. The method for forming a thin film according to item 1. 7. A method of forming a thin film on the entire surface of a substrate, wherein the step of attaching the droplet to the substrate surface in an optimum pattern includes the step of forming a circular droplet concentric with the center of the substrate at the center of the substrate. An adhesion pattern and a plurality of annular droplet attachment patterns concentric with the circular pattern on the outer peripheral side thereof are formed with the same thickness, and the areas of the circular pattern and the annular pattern are reduced from the center of the substrate. 2. The method according to claim 1, wherein the thickness is gradually increased toward an outer peripheral portion.