KR20050057999A - Manufacturing method of micro-lens - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a micro lens, and more particularly, to a method for manufacturing a micro lens using a shadow mask in order to enable the micro lens to be manufactured in-situ with an organic EL element.

By using the present invention, the microlenses can be formed in-situ with the organic EL element, so that not only the out coupling of the organic EL element can be maximized, but also the manufacturing cost can be reduced. And the effect is to simplify the process.

Description

Manufacturing method of micro-lens

The present invention relates to a microlens manufacturing method, and more particularly, to a microlens manufacturing method for maximizing out coupling of an organic EL device.

In general, organic EL devices have a large loss in efficiency due to low out coupling of light generated inside the device.

There are two ways to improve the out coupling of the organic EL device. One method is to reduce the internal reflection at the interface between the substrate and the outside, and the other is to adjust the ratio of ITO to the organic film.

In the former, there is a method of forming the surface of the interface between the substrate and the outside unevenly, attaching silica microspheres or microlens. There are ways to change the regulation rate, and device patterning for photonic crystal operation.

1 is a cross-sectional view of an organic EL element with a microlens, including an organic EL element comprising a glass substrate 11, an ITO electrode 12, an organic layer 13, and a cathode electrode 14, and the glass substrate 11. It consists of the micro lens 15 formed on the surface.

The microlens 15 reflects the light totally reflected inside the organic EL device at various angles to be emitted to the outside through the surface. The microlens 15 has a periodic pattern shape in order to have more excellent light emission efficiency. It is preferable. That is, it is preferable to configure in the form of an array.

Typically, a micro lens array has a structure in which microlenses are arrayed with diameters of approximately 2 or 3 microns to 200 or 300 microns and an approximately hemispherical cross section, respectively.

At present, a number of techniques exist for manufacturing micro lenses.

In a conventional microlens manufacturing method (described in M.Oikawa, et al., Jpn. J. Appl. Phys. 20 (1) L51-54, 1981) using an ion exchange method, by using an ion exchange method The refractive index rises at plural places of the multicomponent glass substrate. Thus, a plurality of lenses are formed at the high refractive index place. In this method, however, the diameter of the lens cannot be large compared to the distance between the lenses. Therefore, it is difficult to design a lens having a large numerical aperture (NA). In addition, in order to produce such a microlens array, a large-scale manufacturing apparatus such as an ion diffusion device is required, so that it is difficult to manufacture a wide area microlens array. Moreover, compared with the shaping | molding method which uses a metal mold | die, it is necessary to give an ion exchange process to each glass. Therefore, unless the management of manufacturing conditions in the manufacturing apparatus is carefully carried out, a change in the quality of the lens, such as the focal length, is likely to increase between the lots. In addition, the cost of using this method is relatively high compared to the method using a mold.

In addition, in the ion exchange method, since the ion which is alkali for ion exchange on a glass substrate is indispensable for a glass substrate, a board | substrate material is limited to alkali glass. However, alkali glass is not suitable for semiconductor based devices that must be free of alkali ions. Moreover, the coefficient of thermal expansion of the glass substrate differs considerably from that of the light irradiation or receiving element substrate, so that as the integration density of the elements increases, the mismatch between the coefficients of thermal expansion increases between the microlens array and the elements. Misalignment is likely to occur.

Compression strains are also inherent on the glass surface treated by the ion exchange method. Therefore, the glass tends to be twisted, so that as the size of the micro lens array increases, bonding or bonding between the glass and the light irradiation or receiving element becomes difficult.

In another conventional microlens array manufacturing method using a resist reflow (or dissolution) method (see D. Daly, et al., Proc. Microlens Arrays Teddington., P23-34, 1991), photolithography techniques are employed. The resin formed on the substrate is patterned in a cylindrical shape, and the resin is heated and reflowed to produce a micro lens array. The resist reflow method can be used to produce various types of lenses at low cost. In addition, in contrast to the ion exchange method, this method does not have problems such as coefficient of thermal expansion, warp, and the like.

However, in the resist reflow method, the profile of the microlenses depends greatly on the thickness of the resin, the wet conditions between the substrate and the resin, and the thermal temperature. Therefore, while the refresh rate per single substrate surface is high, variations between lots are likely to occur. In addition, when adjacent lenses are brought into contact with each other due to reflow, the desired lens profile cannot be obtained due to the surface tension. Therefore, it is difficult to achieve high light collecting rate in a manner of contacting adjacent lenses and reducing the unused area between the lenses. In addition, where a lens diameter of 20 or 30 microns to 200 or 300 microns is desired, the thickness of the deposited resin should be large enough to obtain a spherical surface by reflow. However, it is difficult to deposit a resin material having desired optical properties uniformly and thickly. Thus, it is difficult to produce micro lenses with large curvatures and relatively large diameters.

In another conventional method, an original plate of microlenses is manufactured, and the lens material is deposited on the original plate, and then the deposited lens material is separated. The one plate or mold is manufactured by an electron beam lithography method (see Japanese Patent Laid-Open No. 1 (1989) -261601), or a wet etching method (see Japanese Laid-Open Patent Publication No. 5 (1993) -303009). In these methods, the microlenses can be molded and reproduced, and no change between the lots occurs, so that the microlenses can be manufactured at low cost. Also, in contrast to the ion exchange method, the problem of alignment error and warp due to the difference in thermal expansion coefficient can be solved.

However, in the ion beam lithography method, since the ion beam lithography apparatus is expensive, a large investment is required. In addition, since the electron beam impact region is limited, it is difficult to manufacture a mold having a large region of 100 cm 3 or more.

In addition, in the wet etching method, isotropic etching using a chemical reaction is used in principle, so that even if the composition and crystal structure of the metal plate change only slightly, the metal plate cannot be etched to the desired profile. Also, if the plate is not cleaned immediately after obtaining the desired shape, the etching will continue. In the case of forming the micro microlens, a shape may deviate from the desired due to the etching lasting for a period from the time at which the desired profile is obtained to the time at which the microlens is obtained.

There is also a method of manufacturing a mold using an electroplating technique (see Japanese Patent Application Laid-Open No. 6 (1994) -27302). In this method, an insulating film having a conductive layer and an opening formed on one surface is used, so that a protrusion serving as a mother mold is formed on the surface of the insulating film after the conductive layer serving as the cathode is electroplated. . The process of manufacturing the mold by this method is simple and the cost is reduced. Similar methods are also disclosed in Japanese Patent Application Laid-Open No. 8 (1996) -258051 and Japanese Patent Application Laid-Open No. 64 (1989) -10169.

Problems that occur when the plating layer is formed in the opening by the electroplating technique will be described with reference to FIGS. 2A and 2B. 2A and 2B show the diameter deformation and distribution of the plating layer 105 formed in the two-dimensional array on the substrate 101. In the above-described manufacturing method using the electroplating method in an electroplating bath, an opening pattern (e.g., formed in the insulating mask layer 103 so that the distribution or deformation of the electroplating-current density exposes the electrode layer 102) For example, on the substrate 101 due to the electrode pattern). In particular, the electric field is unevenly concentrated (stronger at the periphery than at the center), and electroplating growth is promoted near the periphery of the pattern of the arrayed openings. As a result, there is a distribution or change in the size of the hemispherical microstructure 105 in the substrate 101. Thus, when such a substrate is used as a mold for a micro lens array, the details of each micro lens are changed on the array.

In order to maximize the out coupling of the organic EL device, the manufacturing process of the microlens should be performed in-situ with the organic EL device.

However, the above-described microlens manufacturing methods are methods of breaking the vacuum state of the equipment and additionally performing a post-treatment process after making the organic EL device in a vacuum deposition apparatus. There are many difficulties in producing wine-the-situ.

The present invention has been made to solve the above problems, and an object thereof is to provide a method for manufacturing a micro lens that can be formed in-situ with an organic EL device.

Another object of the present invention is to provide a microlens fabrication method capable of maximizing out coupling of an organic EL element by forming the microlens in-situ with the organic EL element.

In accordance with another aspect of the present invention, there is provided a method of manufacturing a microlens shadow mask, a method of manufacturing a shadow mask for a microlens, aligning the shadow mask on a substrate on which an organic EL device is formed, and then vacuum depositing the substrate. It characterized in that the forming comprising the step of forming a micro lens.

Preferably, the step of forming the micro lens is characterized in that to proceed with the organic EL device manufacturing process in-situ (In-situ).

Preferably, the vacuum deposition process is carried out using any one of evaporation, sputtering, chemical vapor deposition, sputter chemical vapor deposition.

Other objects, features and advantages of the present invention will become apparent from the following detailed description of embodiments taken in conjunction with the accompanying drawings.

Hereinafter, with reference to the accompanying drawings illustrating the configuration and operation of the embodiment of the present invention, the configuration and operation of the present invention shown in the drawings and described by it will be described as at least one embodiment, By the technical spirit of the present invention described above and its core configuration and operation is not limited.

3 is a view showing a shadow mask used in the present invention, Figure 4 is a view showing a micro lens manufacturing method according to an embodiment of the present invention.

The present invention proposes a method of manufacturing a microlens by using a shadowing effect of a shadow mask. First, as shown in FIG. 3, an appropriate shape according to the size of a microlens to be formed is shown. A shadow mask 202 having a size and a size is manufactured.

Since the microlenses will be manufactured using the shadowing effect of the shadow mask, the thickness of the shadow mask and the hole inclination of the shadow mask are very important parameters. Therefore, it is necessary to appropriately adjust these in the shadow mask manufacturing process.

Then, an organic EL device is fabricated by forming an ITO electrode, an organic layer, and a cathode on the substrate 201 in a vacuum chamber, and then, as shown in FIG. 4 while maintaining the vacuum state of the chamber. The shadow mask 202 is aligned on the lower portion of the substrate 201.

In this case, since the microlenses will be manufactured using the shadowing effect of the shadow mask, it is necessary to appropriately adjust the distance between the substrate 201 and the shadow mask 202 to form the microlenses.

Subsequently, a vacuum deposition process is performed in-situ to form the microlens 203 on the portion of the substrate 201 that is not shadowed by the shadow mask 202.

As the deposition process, all vacuum deposition methods such as evaporation, sputtering, chemical vapor deposition (CVD), and sputter CVD can be used. However, since the deposition process is a process using a shadow effect, it is more preferable to use a deposition method excellent in straightness, such as evaporation and sputter CVD, which applies a bias to the substrate to increase the straightness.

The micro lens manufacturing is completed by the above method.

The microlens manufacturing method of the present invention as described above has the following effects.

First, since the microlenses are formed in the vacuum chamber in which the organic EL device is manufactured, there is no need to use separate equipment for forming the microlenses, thereby reducing the device manufacturing cost.

Second, since the microlens is formed in-situ with the organic EL element, the microlens can be manufactured immediately after forming the organic EL element, thereby simplifying the process and shortening the manufacturing time. have.

Third, since the microlens is formed in-situ with the organic EL element, it is possible to maximize the out coupling of the organic EL element.

Those skilled in the art will appreciate that various changes and modifications can be made without departing from the spirit of the present invention.

Therefore, the technical scope of the present invention should not be limited to the contents described in the examples, but should be defined by the claims.

1 is a cross-sectional structure diagram of an organic EL device with a microlens

Figure 2a is a cross-sectional view of a conventional micro lens array formed by the electroplating method

Figure 2b is a plan view of a conventional micro lens array formed by the electroplating method

3 is a plan view of a shadow mask used in the present invention

4 is a cross-sectional view illustrating a method of manufacturing a microlens according to the present invention.

** Description of the symbols for the main parts of the drawings **

201: substrate 202: shadow mask

203: Micro Lens

Claims (3)

Manufacturing a shadow mask for a micro lens, And aligning the shadow mask to a substrate on which an organic EL element is formed, and then forming a micro lens on the substrate by a vacuum deposition process. The method of claim 1, And forming the micro lens in the organic EL device manufacturing process and in-situ. The method of claim 1, The vacuum deposition process is performed by any one of evaporation method, sputtering method, chemical vapor deposition method, sputter chemical vapor deposition method.