JP2013071084A - Pattern forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pattern forming method, capable of forming a pattern with high aspect ratio by attaining miniaturization of drawing line width and increase in thickness.SOLUTION: A landed third droplet is spread in wet condition without hardening in such a manner that hardened first droplets 2 are bridged to fill up the space between the first droplets 2. According to this, a pattern forming method capable of forming a line with miniaturized drawling line width and high aspect ratio is obtained. Since each of the first droplet, second droplet, third droplet and fourth droplet is landed and disposed at the same pitch, aggregation of droplets or the like occurs in the same manner, and a pattern with uniform line width can be obtained.

Description

  The present invention relates to a pattern forming method for forming a predetermined pattern by discharging droplets onto a substrate using an inkjet method, and more particularly to a pattern forming method that enables a pattern with a high aspect ratio.

In recent years, a pattern forming method is known in which droplets are ejected using an ink jet method to form a pattern on a substrate. Conventional pattern formation methods using lithography require costly processes such as a vacuum film formation process, a photolithography process, an etching process, and a resist stripping process.
However, since the above-described steps can be omitted by using an inkjet method for forming the pattern, the pattern can be formed at low cost.
In particular, when drawing a wiring pattern on a substrate, it is necessary to increase the cross-sectional area of the wiring pattern in order to reduce the wiring resistance. On the other hand, with the miniaturization of the circuit, it is preferable that the wiring width is small. Therefore, a technique for forming a high-aspect-ratio thick thin-line pattern is required in the circuit board wiring creation technique.

When a pattern is formed on a substrate using an ink jet method, a droplet made of fluid ink is ejected and landed at a predetermined position on the substrate to form a wiring. Here, there is a possibility that ink droplets gather due to the surface tension, and aggregates composed of ridged ink reservoirs (bulges) are formed on the substrate. If most of the landed ink droplets are concentrated on the bulge, an extreme difference occurs in the pattern width and pattern thickness in the formed pattern, which is not preferable. For this reason, a technique is disclosed in which a desired pattern can be formed on a substrate while preventing the landed ink droplets from spreading too much or separating the ink droplets from each other as much as possible (for example, Patent Document 1). reference).

The resin film forming method described in Patent Document 1 includes a first resin liquid disposing step of disposing a plurality of first resin liquid droplets on a substrate so as not to contact each other, and a first resin liquid disposing step on the substrate. A first resin liquid curing step for curing at least the surface of the resin liquid, and after at least the surface of the first resin liquid droplets are cured, the second resin liquid is provided at the approximate center between the first resin liquid droplets on the substrate. A second resin droplet arranging step of arranging the droplets, and a second droplet curing step of curing the droplets of the second resin liquid arranged on the substrate.

According to this resin film forming method, the first resin liquid droplets do not coalesce with each other by disposing the first resin liquid droplets on the substrate, and the surface is at least cured. By disposing the second resin liquid droplet between the first resin liquid droplets, the second resin liquid droplet wets and spreads so as to bridge between the adjacent first resin liquid droplets. As a result of filling the gaps between the droplets of the resin liquid, it is possible to make the width and film thickness of the resin film pattern uniform without generating bulges and the like.

JP 2008-253859 A

  However, in the resin film forming method which is a pattern forming method described in Patent Document 1, when the drawing line width is reduced and the film thickness is increased by the ink jet method, the drawing line width is reduced only by overcoating. It is difficult to draw lines with high aspect ratio.

The present invention has been made in consideration of such circumstances, and an object of the present invention is to provide a pattern forming method that enables a high aspect ratio pattern by realizing a finer and thicker drawing line width. It is in.

In order to achieve the above-described object, a pattern forming method according to the present invention is a pattern forming method for forming a pattern on a substrate by ejecting ink as droplets by an inkjet method, and at least droplets landed on the substrate A first droplet disposing step of ejecting droplets at a pitch larger than the diameter of the first droplet, disposing a plurality of first droplets spaced apart on the substrate, and the first liquid disposed on the substrate A first droplet curing step for curing the droplets, and a second droplet for discharging a plurality of second droplets and landing the second droplets in the middle of the separated first droplets An arrangement step, a second droplet curing step for curing the second droplet arranged between the first droplets, a plurality of third droplets being ejected, and the second liquid A step of landing on the droplets and spreading them without curing, and discharging a plurality of fourth droplets; A fourth ink drop placement step of landing co-located with the droplets, characterized in that it comprises a first droplet curing step to cure the fourth droplet.

  The landed third droplet does not cure, but spreads so as to bridge between the cured first droplets and fills the space between the first droplets. As a result, there is obtained a pattern forming method in which the variation in height is small, the drawing line width is reduced, and a line having a high aspect ratio can be formed.

  In the pattern forming method according to the present invention, the first droplet, the second droplet, the third droplet, and the fourth droplet are all landed and arranged at the same pitch. It is characterized by.

  Since the first droplet, the second droplet, the third droplet, and the fourth droplet are all landed at the same pitch, the aggregation of the droplets occurs in the same manner, and the line width is A uniform pattern is obtained.

  In the pattern forming method according to the present invention, the ink is made of an optical material.

  When the ink is composed of an optical material and a pattern is formed, matching with the optical design becomes good, and as a result, optical characteristics can be improved.

According to the above pattern formation method, a fine wiring with low resistance can be achieved by increasing the pattern thickness to a high aspect ratio (pattern thickness / pattern width).
In addition, as a result of forming a prism pattern with ink made of optical material and increasing its thickness to a high aspect ratio (pattern thickness / pattern width), the matching with the optical design is good. There is an effect that the characteristics are improved.

FIG. 5 is a schematic diagram illustrating a state where the first droplet and the second droplet are landed on the substrate in the embodiment. FIG. 1A is a schematic diagram in which first droplets are landed and arranged, and FIG. 1B is a schematic diagram in which second droplets are landed and arranged between first droplets. The figure which showed the hardening state of the pattern when the hardening time of a 2nd droplet was varied with 0.9 second, 1.2 second, 3.5 second, 5.5 second, and 10 second. The figure which shows the example of pattern formation.

The pattern forming method of the present invention includes a liquid repellent treatment step, a first droplet placement step, a first droplet curing step, a second droplet placement step, a second droplet curing step, A third droplet placement step, a fourth droplet placement step, and a fourth droplet curing step are included. Hereinafter, the pattern forming method of the present invention will be described in detail with reference to embodiments.
FIG. 1 is a schematic diagram illustrating a state in which the first droplet and the second droplet are landed on the substrate in the embodiment. (A) is a schematic diagram in which the first droplet 2 is landed and arranged, and (B) is a schematic diagram in which the second droplet 3 is landed between the first droplets 2.

First, the time until ultraviolet curing of the droplets ejected from the inkjet head was examined.
Here, a liquid repellent treatment step, a first droplet placement step, a first droplet curing step, a second droplet placement step, and a second droplet curing step are performed to The time until UV curing was examined.

(Liquid repellent treatment process)
In the liquid repellent treatment step, a liquid repellent treatment was performed on the acrylic substrate 1 as a surface treatment.
First, foreign matter removal cleaning is performed on the surface of the acrylic substrate 1 to remove foreign matter from the surface of the acrylic substrate 1. Next, a known liquid-repellent material (for example, an acrylic resin material containing fluorine containing an ultraviolet curable resin) is applied to the surface of the acrylic plate 1 that has been subjected to foreign substance removal cleaning by spin coating, and then dried. Thereafter, the liquid repellent material was cured with ultraviolet rays.
In the liquid repellent treatment of the surface of the acrylic substrate 1, when the ejected ink droplets land on the acrylic substrate 1, the contact angle with respect to the ink is preferably in the range of about 25 ° to about 70 °.

(First droplet placement step)
Next, ink (ink containing an ultraviolet curable resin that is cured by ultraviolet irradiation) is formed into droplets on the acrylic substrate 1 that has been subjected to the liquid repellent treatment by an inkjet head that is used in an inkjet method, and a plurality of second inks are directed toward the acrylic substrate 1. One droplet 2 is discharged and landed on the acrylic substrate 1.
The pitch of the first droplets 2 ejected from the inkjet head is 141 μm, and is set to be larger than the diameter of the droplets. The pitch of adjacent line patterns was set to 70 μm. For this reason, the first droplets 2 are disposed on the acrylic substrate 1 so as to be separated from each other.
The ink of the first droplet 2 was used with a viscosity (10.4 mPa · s (at 25 ° C.)), a surface tension (24 mN / m), and a discharge temperature of 30 ° C.

(First droplet curing step)
The first droplet 2 was discharged from the inkjet head, and 0.9 seconds later, the first droplet 2 was cured by irradiating with an ultraviolet ray with an ultraviolet lamp disposed in the vicinity of the inkjet head.

(Second droplet placement step)
The second droplet 3 is ejected from the inkjet head as a plurality of droplets, and is landed between the first droplets 2 disposed on the acrylic substrate 1. At this time, the second droplet 3 is brought into contact with the first droplet 2. The pitch of the second droplets 3 ejected from the inkjet head is set to 141 μm, which is larger than the diameter of the droplets, like the first droplet 2.

(Second droplet curing process)
The second droplet 3 is ejected from the ink jet head and then cured by irradiating with ultraviolet light from an ultraviolet lamp disposed in the vicinity of the ink jet head. The degree of curing of the ink was observed by varying the time from 2 seconds, 3.5 seconds, 5.5 seconds, and 10 seconds.

FIG. 2 shows the cured state of the pattern. (A) 0.9 seconds later, (B) 1.2 seconds later, (C) 3.5 seconds later, (D) 5.5 seconds later, (E) 10 seconds later. Show.
As a result, a bulge was partially generated because the time until curing by ultraviolet irradiation was pulled by the first droplet 2 except for 0.9 seconds. From this result, 0.9 seconds was selected as the time to cure by ultraviolet irradiation.
Here, when the ultraviolet lamp irradiation reaches the inkjet head, the resin at the ejection port of the inkjet head is cured and the ejection operation is hindered. Therefore, it is important that the ultraviolet lamp is directed to the substrate side.

FIG. 3 shows an example of pattern formation in Comparative Example A and Example B.
(Comparative Example A)
After the first droplet to the fourth droplet landed on the substrate, they were cured with ultraviolet rays.
The liquid repellent treatment step, the first droplet placement step, the first droplet curing step, the second droplet placement step, and the second droplet curing step were performed by the method described above.

(Third droplet placement step)
A plurality of third droplets were ejected from the inkjet head under the same conditions as the second droplet 3, and ejected so as to land on the same location as the second droplet 3 disposed on the acrylic substrate 1. This is because the second droplet 3 landed and arranged between the first droplets 2 is pulled by the first droplet 2, and the second droplet landed and arranged between the first droplets 2. Because the amount of 3 is reduced, it is for replenishment.

The third droplet 3 is ejected from the inkjet head and then cured by irradiating ultraviolet rays with an ultraviolet lamp disposed in the vicinity of the inkjet head after 0.9 seconds, like the first droplet 2.

(Fourth droplet placement step)
A fourth droplet was ejected from the inkjet head under the same conditions as the second droplet 3, and landed at the same location as the second droplet 3 disposed on the acrylic substrate 1.

(Fourth droplet curing process)
Similarly to the second liquid droplet 3, the fourth liquid droplet was discharged from the ink jet head, and 0.9 seconds later, it was cured by irradiating it with an ultraviolet ray lamp disposed in the vicinity of the ink jet head.
As shown in FIG. 3, the width of the line pattern at this time was about 66 μm, the contact angle was about 44 °, the height was about 13 μm, and the variation in height was about 0.8 μm although not shown. In the obtained line pattern, no bridge is generated between adjacent line patterns. The aspect ratio at this time was 13 μm / 66 μm = about 0.2.

(Fifth droplet placement step)
Furthermore, in order to increase the film thickness, a plurality of fifth droplets were ejected from the inkjet head, and landed at the same location as the fourth droplets disposed on the acrylic substrate 1.

(Fifth droplet curing step)
Similarly to the fourth droplet, the fifth droplet was discharged from the inkjet head, and 0.9 seconds later, the fifth droplet was cured by irradiating it with an ultraviolet lamp disposed in the vicinity of the inkjet head.
As shown in FIG. 3, the width of the line pattern at this time was about 51 μm, the contact angle was about 54 °, the height was about 15 μm although not shown, and the height variation was about 2.1 μm. In the obtained line pattern, no bridge is generated between adjacent line patterns. The aspect ratio at this time is 15 μm / 51 μm = about 0.29. The line pattern obtained by landing the fifth droplet has a good width and contact angle, but the variation in height becomes large and a good line pattern cannot be obtained.

(Example B)
In Comparative Example A, the third droplet curing step was not performed and UV curing was not performed.
In this case, the landed third droplet does not cure, but spreads so as to bridge between the cured first droplets 2 and fills the space between the first droplets 2.
In Example B, after curing the fourth droplet, as shown in FIG. 3, the width of the line pattern is about 50 μm, the contact angle is about 53 °, the height is about 15 μm, although the height variation is not shown. It was about 0.4 μm. The aspect ratio at this time is 15 μm / 50 μm = 0.3. In the obtained line pattern, no bridge was generated between adjacent line patterns, and a good line pattern was obtained.

In Example B, after the fifth droplet was cured, as shown in FIG. 3, the width of the line pattern was 60 μm or more, and bonding was generated between adjacent line patterns. For this reason, it has been found that landing the fifth droplet is not suitable.
As a result, the variation in height is small, and it is possible to reduce the drawing line width and form a line with a high aspect ratio.

In Comparative Example A and Example B, the first to fifth droplets were ejected from one inkjet head using the same ink material.
When the ejection conditions, ink conditions, curing time, etc. of the inkjet head are optimized, a plurality of droplets are ejected between the second droplet and the last droplet to increase the film thickness. However, in order to reduce the drawing line width and obtain a high aspect ratio, at least a step for spreading the liquid droplets without curing them is necessary.
Further, when the ink material is composed of an optical material (for example, acrylic resin, polycarbonate resin, etc.) and a pattern is formed, the optical characteristics can be improved as a result of good matching with the optical design. .
In addition, the present invention can be variously modified and implemented without departing from the scope of the invention.

  1: acrylic substrate, 2: first droplet, 3: second droplet.

Claims (3)

A pattern forming method for forming a pattern on a substrate by ejecting ink as droplets by an inkjet method, wherein the droplets are ejected at a pitch larger than the diameter of the droplets landed on the substrate, A first droplet disposing step of disposing a plurality of first droplets apart from each other;
A first droplet curing step for curing the first droplet disposed on the substrate;
A second droplet disposing step of ejecting a plurality of second droplets and landing the second droplet in the middle of the spaced apart first droplets;
A second droplet curing step for curing the second droplet disposed between the first droplets;
Discharging a plurality of third droplets, placing and landing on the second droplets, and spreading out without curing;
A fourth droplet placement step of discharging a plurality of fourth droplets and landing at the same position as the third droplet;
And a fourth droplet curing step for curing the fourth droplet. In the pattern formation method of Claim 1,
The pattern forming method, wherein the first droplet, the second droplet, the third droplet, and the fourth droplet are all landed and arranged at the same pitch. In the pattern formation method of Claim 1 or Claim 2,
A pattern forming method, wherein the ink is made of an optical material.