KR101688457B1

KR101688457B1 - Laser direct writing apparatus using micro lens

Info

Publication number: KR101688457B1
Application number: KR1020150141296A
Authority: KR
Inventors: 김기홍; 이재종; 최기봉; 임형준; 권순근
Original assignee: 한국기계연구원
Priority date: 2015-10-08
Filing date: 2015-10-08
Publication date: 2016-12-22

Abstract

The laser direct writing apparatus of the present invention comprises a substrate to which a photosensitive liquid is applied; A laser generating unit for irradiating a laser; A microlens array disposed on a path of a laser beam emitted from the laser generation unit and having a plurality of microlenses formed therein; A condenser lens disposed between the microlens array and the substrate, for condensing a plurality of laser beams passing through the microlens array to cause mutual interference; And a filtering window disposed between the condenser lens and the substrate for filtering one specific beam in a condensed region where interference of the laser beam passing through the condenser lens occurs; And is formed to include a plurality of protrusions. Accordingly, the present invention has the advantage that the size of the light spot that can be utilized in the laser direct drawing process is drastically reduced, and a finer pattern can be accurately manufactured than the conventional method.

Description

Technical Field [0001] The present invention relates to a laser direct writing apparatus using a micro lens,

The present invention relates to a laser direct writing apparatus using a microlens, more specifically, a microlens array having a plurality of microlenses formed therein is disposed in front of a condensing lens, and a multiple interference phenomenon To a laser direct writing apparatus capable of forming a light spot with a very narrow width by effectively controlling the angle of the laser beam.

The laser direct writing technique is applied to various fields such as micro-machining, surface treatment, and deposition. The laser light and the microscope optical system are used to process the laser light. The laser light from the laser source passes through the objective lens When the condensing beam is irradiated onto the substrate to which the photoresist is applied, a curing reaction occurs in the photosensitive liquid at the portion where the condensing beam is formed. Then, the position of the condensing beam is determined using a mechanical or optical device Direction, and the curing process is carried out in the form of a desired pattern.

After completing the fabrication of the photoresist pattern by the above-described method, a photoresist-free portion is removed using a developing solution, or the photocured portion is removed to leave a desired pattern on the substrate.

As a technology related to this, Korean Patent Laid-Open No. 2009-0096298 (published on Dec. 18, 2008, entitled "Laser Direct Drawing Apparatus") is available.

In recent years, there has been a growing demand for manufacturing fine patterns in various electronic products, optical parts, and nano parts, and accordingly, research is underway to reduce the size of the condensed beam in laser direct drawing technology to produce a finer pattern.

In order to fabricate a fine pattern, the laser direct light drawing technique converges the laser light with the objective lens. Therefore, an object lens having a high magnification is used if possible. Generally, when an oil immersion type 100 objective lens is used, A condensing beam size of 200 to 300 nm can be realized.

In this laser direct drawing technique, the most effective way to reduce the size of the pattern is to reduce the diameter of the condensing beam as much as possible, but conventionally, it was the only way to utilize a high magnification objective lens or utilize a short wavelength laser.

However, since the wavelength of the laser is determined according to the sensitizing solution to be used and the type of the objective lens to be used is constant, there is a limit in reducing the size of the pattern by the above-described method.

Another technique for producing a pattern by reacting a sensitizing solution is an interference lithography technique. Laser interference lithography is a technique for performing exposure using an interference pattern that occurs in a superposition region of light with a high degree of coherence having several traveling wave vectors.

This method separates the parallel laser beam into two and then superimposes it on the surface to which the photosensitive liquid is applied. At this time, an interference pattern due to two laser light interference is generated in the overlapped region. Patterns are produced.

Figure 1 is a general schematic diagram of interference lithography. In the interference lithography, various optical methods can be used in the method of separating incident laser light into two, but it can be considered that they are similar in terms of producing a periodic pattern as shown in FIG. 1 by superimposing the separated lights again.

In interference lithography, the size of one pattern may be as small as 100 nm or less, but it is not possible to specify one light spot because it is intended to form a periodic pattern. In addition, if the size of the pattern is small, the pitch, which is the distance to the neighboring pattern, is small, so that it is not easy to separate only one interference pattern optically or mechanically.

Therefore, it is necessary to study how to define one specific beam of very small size that can be used in laser direct drawing process.

Domestic registered patent No. 0860953 (registered on September 30, 2008, name: Roll stamp production method for imprint)

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned problems, and it is an object of the present invention to provide a laser apparatus and a method of manufacturing the same, which can greatly reduce the size of a light spot that can be utilized in a laser direct- And to provide a direct drawing apparatus.

The laser direct writing apparatus according to the present invention comprises a substrate coated with a photosensitive liquid; A laser generating unit for irradiating a laser; A microlens array disposed on a path of a laser beam emitted from the laser generation unit and having a plurality of microlenses formed therein; A condenser lens disposed between the microlens array and the substrate, for condensing a plurality of laser beams passing through the microlens array to cause mutual interference; And a filtering window disposed between the condenser lens and the substrate for filtering one specific beam in a condensed region where interference of the laser beam passing through the condenser lens occurs; And is formed to include a plurality of protrusions.

In this case, the laser direct-write apparatus separates the laser beams having passed through the microlens array by the number of the microlenses, generates an interference pattern by multiple interference generated by the condenser lens, The laser direct drawing can be performed only by one light spot having a plurality of light spots passing through the filtering window and being specially constructed.

In addition, the filtering window can filter a plurality of light spots forming an interference pattern by a mechanical or optical method to specify one light spot.

In addition, the microlens array may have a plurality of microlenses spaced apart from each other at regular intervals or may be arranged so as to have a constant shape.

In one embodiment, the microlens array may include a plurality of microlenses arranged in a cross shape or a plurality of concentric circles.

Accordingly, the laser direct writing apparatus of the present invention can effectively control the angle of the laser beam by using the multiple interference phenomenon generated by overlapping the plurality of laser beams passing through the microlens array while passing through the condenser lens, There is an advantage that a narrow light spot can be formed.

More specifically, in conventional laser direct-write techniques, there has been an attempt to reduce the size of a light spot for producing a fine pattern. In order to minimize the diameter of a light spot, an objective lens having a high magnification is used, A laser of short wavelength was utilized. However, in this case, the magnification of the objective lens that can be used is limited, and since the wavelength of the laser is determined according to the sensitizing solution, it is difficult to make a light spot of 100 nm or less.

Therefore, in the present invention, the multi-interference phenomenon used in the conventional interference lithography is utilized to make the laser light focus of 100 nm or less, and the angle of the plurality of laser beams generated while passing through the microlens array is controlled, To be cured.

Thus, the laser direct-write apparatus of the present invention can produce a finer pattern precisely than the conventional laser direct-write method.

1 is a general conceptual view of interference lithography.
Figure 2 is an ideal form of interference pattern to be made using multiple interferences for implementation of a laser direct imaging apparatus in accordance with the present invention.
Fig. 3 is an optical configuration diagram of Equation 4; Fig.
FIG. 4 is a graph illustrating the form of an interference signal in a two-beam interference lithography configuration according to a change in the number of laser beams. FIG.
5 is a conceptual diagram showing a laser direct drawing apparatus according to the present invention.
6 is a diagram schematically showing a state where light spots due to multiple interference are formed on a filtering window in a laser direct drawing apparatus according to the present invention.
7 is a conceptual diagram illustrating a laser direct-write apparatus according to an embodiment of the present invention.

Hereinafter, the laser direct drawing apparatus according to the present invention as described above will be described.

The present invention relates to a laser direct imaging apparatus using a microlens array 20 and includes a substrate 40, a laser generation unit 10, a microlens array 20, a condenser lens 30, and a filtering window 50, .

The substrate 40 may be a glass substrate 40 and is coated with a photo-curable photoresist to which a laser is applied.

The laser generator 10 irradiates a laser having a predetermined wavelength to cure the photosensitive liquid applied on the substrate 40.

The microlens array 20 is disposed on the path of the laser beam emitted from the laser generator 10, and a plurality of microlenses 21 are formed at regular intervals.

The condenser lens 30 is a so-called objective lens and is disposed between the microlens array 20 and the substrate 40. A plurality of lasers passing through the microlens array 20 are condensed to cause mutual interference do.

The filtering window 50 is disposed between the condensing lens and the substrate, and filters the specific beam in the condensing region where interference of the laser beam passing through the condensing lens occurs.

In this case, the filtering window 50 may be formed by a mechanical filtering method in which only a light spot located in the middle region is passed through the filtering window 50 as shown in FIG. 6, May be formed so as to be specific.

5 is a conceptual diagram showing a laser direct drawing apparatus according to the present invention. The operation of the laser direct writing apparatus of the present invention will be described with reference to FIG. 1. The laser generated from the laser generating unit 10 passes through the microlens array 20. In this process, 21).

Then, the laser beams are condensed while passing through the condenser lens 30 and collected at one point on the substrate 40 to cause mutual interference. As shown in FIG. 3, the laser beams combined by the condenser lens are subjected to multiple interference Thereby generating a constant interference pattern.

In this case, unlike the interference pattern of two lasers used in the conventional interference lithography, it is preferable that the width of the light spot is very narrow and the distance between the light points is designed to be long.

Thus, as shown in FIG. 6, of these multiple light spots, one light spot to be used for laser direct drawing can be specifically erased using the filtering window 50.

That is, the laser direct writing apparatus of the present invention passes through the condensing lens 30 and the filtering window 50 among a plurality of light spots passing through the microlens array 20, Cured.

The laser direct imaging apparatus of the present invention is designed by applying the multiple interference phenomenon used in interference lithography, and the background of the design will be described below.

FIG. 2 is a diagram of an ideal interference pattern to be generated using multiple interference, in which it is assumed that a square waveform having a width w and a size 1 is repeated infinitely with a relative distance L.

These waveforms can be easily separated by a combination of cos and sin harmonic functions through Fourier transform, as shown in Equation 1 below.

(Equation 1)

For example, assuming that the width w of the waveform is 100 nm and L = 3 um, the waveform of FIG. 2 is defined as follows.

0 -1.5 < x < -0.05

f (x) = 1 - 0.05 < x < 0.05 (2)

0 0.05 < x < 1.5 Pitch (p) = 2L = 3um

At this time, the coefficient of (Equation 1) is calculated by using (Equation 2) as follows.

(Equation 3)

therefore,

(Equation 4)

In Equation (4), the first term is the DC component, the second term is the interference pattern of the two beams incident at 3.4779 degrees, the third term is 6.9672 degrees, and the fourth term is 10.4794 degrees. Respectively.

FIG. 3 shows a configuration in which a plurality of the two-beam interference lithography of FIG. 1 are implemented simultaneously except for a laser beam of a DC component incident on the center.

4 is a view of the waveform of the interference pattern appearing while increasing the number of two-beam interference lithography in the configuration of FIG. 3, wherein FIG. 4A is the form of the interference signal in five 2-beam interference lithography configurations, b) is the form of the interference signal in the 10 two-beam interference lithography configuration, and Fig. 4 (c) is the waveform showing the interference signal form in the 15 two-beam interference lithography configuration.

As can be seen in FIG. 4, it can be seen that the interference pattern approaches the waveform of FIG. 2 as the number of 2-beam interference lithography increases.

4 (c), the interference waveform is periodic, as is conventional interference lithography, but its distance is sufficiently far away and the remaining waveforms, except for the middle interfering waveform, DC laser beam, Can be sufficiently removed by an optical or mechanical method.

In addition, small waveforms between waveforms can not be cured because the relative intensity is very small, and thus the sensitizing solution can not be cured.

As a method for realizing a plurality of two-beam interference lithography by the above-described principle, in the laser direct writing apparatus of the present invention, the laser irradiated from the laser generating unit 10 is irradiated onto the microlenses 21 Through the array 20, through the focusing lens 30, and then through the filtering window 50.

4, as the number of the two-beam interference lithography increases, small waveforms between the waveforms, that is, noise may be reduced. Therefore, the microlens array 20 includes a plurality of micro lenses 21, Is formed.

The size of the condensing beam differs depending on the magnification of the condenser lens 30 and the height of the condenser lens 30 and the microlens array 20 in addition to the size of the microlens 21, It is desirable to design.

The microlens array 20 may include a plurality of microlenses 21 arranged in a line.

In addition, as shown in FIG. 7, the microlens array 20 may include a plurality of microlenses 21 arranged in a cross shape.

Since the number of the microlenses 21 that can be formed in a certain space may be changed according to the arrangement of the microlenses 21 and the distance between the microlenses 21 and the adjacent microlenses 21 may be different, It can be appropriately selected in consideration of the relationship with other conditions.

Accordingly, in the laser direct writing apparatus of the present invention, the angle of the laser beam is effectively controlled by using the multiple interference phenomenon generated by overlapping the plurality of laser beams passing through the microlens array 20 while passing through the condenser lens 30 There is an advantage that a light spot having a very narrow width can be formed.

In other words, in the present invention, the multi-interference phenomenon used in the conventional interference lithography is utilized to make the laser light focus of 100 nm or less, and the angle of the plurality of laser beams generated while passing through the microlens array 20 is controlled, So that the photosensitive liquid can be hardened only by the light spot.

It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. It goes without saying that various modifications can be made.

10: laser generator
20: microlens array
21: Micro lens
30: condenser lens
40: substrate
50: Filtering window

Claims

A substrate coated with a photosensitive liquid;
A laser generating unit for irradiating a laser;
A microlens array disposed on a path of a laser beam emitted from the laser generation unit and having a plurality of microlenses formed therein;
A condenser lens disposed between the microlens array and the substrate, for condensing a plurality of laser beams passing through the microlens array to cause mutual interference; And
A filtering window disposed between the condenser lens and the substrate for filtering one specific beam in a condensed region where interference of the laser beam passing through the condenser lens occurs; Respectively,
After the laser light having passed through the microlens array is separated by the number of microlenses,
An interference pattern is generated by multiple interference generated by the condensing lens,
Wherein a plurality of light spots forming an interference pattern passes through the filtering window and laser direct drawing is performed only by a single specific light spot.

delete

The method according to claim 1,
The filtering window
Wherein a plurality of light spots forming an interference pattern are filtered by a mechanical or optical method to specify one light spot.

The method according to claim 1,
The microlens array
Wherein the plurality of microlenses are spaced apart from each other at regular intervals or are arranged so as to have a constant shape.

The method according to claim 1,
The microlens array
Wherein a plurality of microlenses are arranged in a cross shape or in a plurality of concentric circles.