WO2006109907A1

WO2006109907A1 - Method and mold for manufacturing a continuous microlens

Info

Publication number: WO2006109907A1
Application number: PCT/KR2005/002887
Authority: WO
Inventors: Chul Jin Hwang; Young Moo Heo; Jong Sun Kim; Young Bae Ko
Original assignee: Korea Institute Of Industrial Technology
Priority date: 2005-04-15
Filing date: 2005-08-31
Publication date: 2006-10-19
Also published as: KR100658163B1; KR20060109370A

Abstract

The present invention provides a method for manufacturing a continuous microlens on a light guiding plate using a semiconductor reflow process. The method comprises a first step of aligning a mask, which includes a first region through which light can be transmitted and a plurality of second regions through which light cannot be transmitted, on a substrate coated with a photoresist and performing a light-exposing process; a second step of developing the light-exposed substrate to obtain a plurality of photoresists in the form of posts; a third step of performing a reflow process to allow the post-shaped photoresists to be curved until the post-shaped photoresists are combined with photoresists adjacent thereto in one direction to form a continuous microlens feature; a fourth step of fabricating a depressed stamper such that the photoresists defining the continuous microlens feature are engraved in a depressed fashion in the depressed stamper; and a fifth step of forming a light guiding plate by using the depressed stamper as a mold such that the continuous microlens is formed in the light guiding plate in a raised pattern.

Description

METHOD FOR MANUFACTURING A MICROLENS WITH REFLOW PROCESS AND LIGHT GUIDE PLATE

USING THE METHOD

Technical Field

[1] The present invention relates to a micro-pattern machining technology and a micro- molding technology, and more particularly, to a method for manufacturing a continuous microlens for controlling light diffusion and a viewing angle in a microlens array, a light guiding plate or the like, and a light guiding plate manufactured according to such a method; and a method for manufacturing a microlens array, a light guiding plate or the like such that a plurality of lenses formed thereon can have a plurality of faces or a plurality of curvatures, and a light guiding plate manufacturing according to such a method.

[2]

Background Art

[3] Generally, contrary to CRTs, PDPs and FEDs, a liquid crystal display (LCD) is a non-luminescent device and thus cannot be used in a dark place without light.

[4] To solve such a disadvantage and allow a liquid crystal display to be used in a dark place, a backlight unit is used as an illumination device that provides light uniformly over an entire panel of the liquid crystal display.

[5] The backlight unit comprises background light sources, a reflection plate for reflecting light, a light guiding plate, a diffusion plate, and the like.

[6] The light guiding plate functions to uniformly radiate light, which is emitted from the background light sources used as light sources at both lateral sides thereof, onto the entire face of the liquid crystal display.

[7] Here, the light guiding plate includes a plurality of prisms arranged in one direction on the entire face thereof such that V-shaped grooves are formed between adjacent prisms, or diffusive ink dots with a certain size arranged thereon.

[8] In the conventional technology, however, the V-shaped groove pattern should be mechanically processed to provide the prisms to the entire face of the light guiding plate. Thus, there are problems in that it is difficult to manufacture a fine V-shaped groove pattern, production time is extended, and production costs increase.

[9] In addition, even in the case of the diffusive ink dot type, an optical efficiency is significantly degraded due to absorption and scattering of a diffusive ink itself.

[10] Furthermore, the liquid crystal display optically requires light with a larger emergence angle such as about 90 degrees with respect to the surface of the display. In a conventional light guiding plate, however, the emergence angle of emitted light is very small on the order of about 30 degrees with the face of the light guiding plate. Thus, there is a problem in that an expensive prism film or diffusion film should be used to increase the emergence angle.

[11] In order to eliminate a film to be used, various patterns have been used. However, there is a problem in that since this pattern is formed through a mechanical process or an etching process, a uniform configuration cannot be easily achieved.

[12] Moreover, an incident angle and the quantity of light optically differ depending on regions on a light guiding plate. Thus, as compared with a case where rricrolenses or prisms are manufactured to have the same optical properties, it is more effective to manufacture rricrolenses or prisms to have different optical properties at different regions on the light guiding plate. However, currently available micro-patterning techniques cannot easily and rapidly manufacture such a pattern with different optical properties.

Disclosure of Invention Technical Problem

[13] The present invention is conceived to solve the aforementioned problems. An object of the present invention is to provide a method for manufacturing a continuous nicrolens on a light guiding plate and a light guiding plate manufactured according to the method, wherein a plurality of rricrolenses with a predetermined size is interconnected in one direction (x-ass or y-ass) to form a single large nicrolens, i.e., the continuous nicrolens.

[14] Another object of the present invention is to provide a method for manufacturing a continuous nicrolens on a light guiding plate and a light guiding plate manufactured according to the method, wherein the size of the continuous nicrolens or the arrangement thereof on the light guiding plate can be easily controlled according to user's intention.

[15] A further object of the present invention is to provide a method for manufacturing a multi-curvature lens on a light guiding plate and a light guiding plate manufactured according to the method, wherein all or at least a portion of a plurality of rricrolenses on the light guiding plate can be easily and simply formed into multi-curvature lenses, and the curvatures or positions of the rrulti-curvature lenses on the light guiding plate can be easily controlled.

[16] The rrulti-curvature lens means a single microlens with different curvatures. The different curvatures mean that curvatures in at least two directions, for example, among x-ass, y-ass and z-ass are different frαn each other.

[17] The present invention is directed to a light guiding plate with a plurality of multi- curvature lenses formed thereon, and a method for manufacturing such a light guiding plate.

[18]

Technical Solution

[19] According to one aspect of the present invention, there is provided a method for manufacturing a continuous microlens on a light guiding plate using a semiconductor reflow process, comprising a first step of aligning a mask, which includes a first region through which light can be transmitted and a plurality of second regions through which light cannot be transmitted, on a substrate coated with a photoresist and performing a light-exposing process; a second step of developing the light-exposed substrate to obtain a plurality of photoresists in the form of posts; a third step of performing a reflow process to allow the post-shaped photoresists to be curved until the post-shaped photoresists are combined with photoresists adjacent thereto in one direction to form a continuous microlens feature; a fourth step of fabricating a depressed stamper such that the photoresists defining the continuous microlens feature are engraved in a depressed fashion in the depressed stamper; and a fifth step of forming a light guiding plate by using the depressed stamper as a mold such that the continuous microlens is formed in the light guiding plate in a raised pattern.

[20] According to another aspect of the present invention, there is provided a method for manufacturing a plurality of multi-curvature lenses using a semiconductor reflow process, comprising a first step of aligning a first mask, which includes a plurality of shield regions through which light cannot be transmitted and of which a part has a different diameter, on a substrate coated with a photoresist and performing a light- exposing process; a second step of developing the light-exposed substrate to obtain a plurality of photoresists in the form of posts; a third step of performing a reflow process to allow the post-shaped photoresists to be curved until at least a part of the post-shaped photoresists forms a multi-curvature lens feature in combination with neighboring photoresists; a fourth step of fabricating a first stamper in which the photoresists of which the at least part has the multi-curvature lens feature formed through the third step are engraved in a depressed fashion; and a fifth step of injection-molding a product using the first stamper as a mold such that a multi-curvature lens is formed in a depressed pattern in the product. Advantageous Effects

[21] According to the present invention, a continuous ndcrolens can be manufactured in such a manner that neighboring photoresists are overlapped with each other through a reflow process, thereby obtaining a continuous nicrolens array pattern through a simplified manufacturing process and reducing production costs and time.

[22] In addition, the diameters or spacing of the photoresists that have been subjected to the reflow process can be controlled so that internal angles of grooves between the photoresists can be arbitrarily obtained according to manufacturer's intention. Thus, there is an advantage in that a continuous nicrolens and a plurality of continuous nicrolens arrays with optical performance which allows light refraction and diffuse reflection to be easily controlled can be applied to a light guiding plate and the like.

[23]

Brief Description of the Drawings

[24] Fig. 1 is a perspective view of a mask for use in the present invention.

[25] Figs. 2 to 4 show light-exposing procedures for fabricating cylindrical photoresists according to an embodiment of the present invention.

[26] Figs. 5 and 6 are sectional views showing the diameters and spacing of the cylindrical photoresists fabricated according to the embodiment of the present invention.

[27] Figs. 7, 8 and 9 show the shapes of the photoresists changed depending on the diameters and spacing thereof after a reflow process according to the embodiment of the present invention.

[28] Figs. 10 and 11 show a process of fabricating a depressed stamper according to the embodiment of the present invention.

[29] Fig. 12 is a schematic view showing a process of fabricating a raised stamper according to the embodiment of the present invention.

[30] Fig. 13 is a perspective view for use in the present invention.

[31] Figs. 14 to 16 show light-exposing procedures for fabricating cylindrical photoresists according to an embodiment of the present invention.

[32] Fig. 17 is a sectional view showing the diameters and spacing of the cylindrical photoresists fabricated according to the embodiment of the present invention. [33] Figs. 18 and 19 show the shapes of the photoresists changed depending on the diameters and spacing thereof after a reflow process according to the embodiment of the present invention. [34] Figs. 20 and 21 show a process of fabricating a stamper according to the embodiment of the present invention. [35]

Best Mode for Carrying Out the Invention [36] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. [37] In the following description, detailed explanation of known related functions and constitutions may be omitted to avoid unnecessarily obscuring the subject manner of the present invention. [38] In the present invention, a mask 121 to be used for a light-exposing process is first fabricated, as shown in Fig. 1. Here, as for the mask 121, a film mask or a chromium mask may be used depending on the precision of a pattern. In case of the use of a chromium mask, the mask can be fabricated with a precision of about 1 mm. [39] Fig. 1 is a perspective view of a mask for use in the present invention. As shown in this figure, the mask 121 comprises a first region 122 through which light can be transmitted, and a plurality of second regions 123 through which light cannot be transmitted. [40] Here, each of the second regions 123 is preferably formed in a circular shape but may be formed in other shapes such as a rectangle, pentagon, hexagon, or the like. [41] In addition, the mask 121 of the present invention may be formed such that the plurality of second regions 123 have the same shape, diameter and spacing, or different diameters and spacing. [42] Furthermore, each of the second regions 123 of the mask 121 is arranged in one direction on a straight line such that neighboring second regions 123 are close to each other. However, the arrangement of the second regions is spaced apart by a proper distance from another arrangement of neighboring second regions. [43] Figs. 2 to 4 shows a light-exposing process of fabricating cylindrical photoresists according to an embodiment of the present invention. [44] As illustrated in Fig. 2, a photoresist (PR) 132 is first coated on a glass or silicone wafer substrate 131 using a spin coater (not shown). Here, the type of the photoresist

132 may vary according to the thickness thereof. [45] When the coating process has been completed, the coated substrate 131 is subjected to soft baking in an oven. At this time, the baking condition is preferably about 2 to 30 minutes at 70 to 120 C. [46] After the soft baking has been completed, as shown in Fig. 3, the mask 121 is aligned on the PR-coated substrate 131 using an alignment key. A light-exposing process is performed for a predetermined period of time. [47] In Fig. 3, R designates the diameter of the second region 123 on the mask 121, and the diameters of the second regions 123 may be the same as or different from one another. In addition, La and Lb designate spacing between the second regions 123 and are different from each other. [48] More specifically, La designates the spacing between the second regions in a horizontal direction, and Lb designates the spacing between the second regions in a vertical direction. La is smaller than Lb. [49] After the light-exposing process has been completed, a developing process is carried out. The developing process is performed through dipping in a developing solution at room temperature. [50] As the results of the light-exposing process, as shown in Fig. 4, the photoresist 132 of the first region 122 through which the light has been transmitted by means of slant light exposure is melted down and disappears. The PR 132 of the second region 123, which has not been exposed to the light, remains as it is. [51] Consequently, only the PR 134 of each of the second regions 123 remains on the substrate 131. At this time, the photoresist 134 has a cylindrical shape through the light exposure since the second region 123 has a circular shape. [52] At this time, the cylindrical photoresists 134 formed through the light-exposing process correspond to the pattern and shape of the second regions 123 in the mask 121. [53] Fig. 5 is a sectional view of the cylindrical photoresists 134 on the light-exposed substrate taken along the direction of smaller spacing, and Fig. 6 is a sectional view of the cylindrical photoresists 134 on the light-exposed substrate taken along the direction of larger spacing. [54] Although the cylindrical photoresists 134 have the same height and diameter as shown in Fig. 5, it can be seen that the horizontal and vertical spacing La and Lb are different from each other. [55] After the completion of the developing process, a reflow process is performed using a hot plate apparatus to allow the cylindrical photoresists 134 to be curved. [56] Here, in the reflow process, the photoresists (PRs) 134 are heated so that the photoresists (PRs) can be melted down. At this time, the reflow condition may vary with a shape to be manufactured, for example, preferably a few minutes at 100 to 200⁰C. [57] Fig. 7 is a plan view showing the state of the PRs after the reflow process according to the present invention, and Figs. 8 and 9 are sectional views showing the state of the

PRs after the reflow process according to the present invention. [58] As shown in these figures, due to the reflow process, the neighboring cylindrical photoresists 134 are overlapped with each other, thereby forming a photoresist 136 in the form of a continuous nicrolens. [59] At this time, an inclination angle defined between the overlapped photoresists, i.e., a groove, is determined on the basis of the diameter of the second region 123 or the spacing between the neighboring second regions 123 in the mask 121. [60] Here, if the neighboring photoresists 134 do not have appropriate diameters and are not sufficiently close to each other, they fail to be overlapped with each other and to form a groove. [61] In the present invention, an appropriate groove can be formed through the following several methods. First, there is a method in which the spacing between the neighboring photoresists 134 is fixed and the diameters of the photoresists 134 are gradually increased to control an overlapping area between the neighboring photoresists after the reflow process. [62] Second, the diameters of the neighboring photoresists 134 are fixed and the spacing between them is gradually decreased to control the overlapping area between the neighboring photoresists 134 after the reflow process. [63] Here, if the overlapping area is small, an internal angle (i.e., inclination angle) of the formed groove, becomes small. As the overlapping area increases, the internal angle (i.e., inclination angle) of the groove becomes larger. [64] Through the above method, the present invention can nutnericalize the internal angle of the formed groove according to the diameters of the photoresists 134 and the spacing between the photoresists 134. [65] That is, in the present invention, the second region 123 of the mask 121 and the temperature and time during the reflow process can be adjusted according to designer's intention. Thus, a groove with a desired shape can be easily achieved, and the curvature of the continuous microlens can be easily controlled in a desired direction. [66] Figs. 10 and 11 shows a process of fabricating a depressed stamper according to the embodiment of the present invention. [67] As shown in these figures, a metallic thin film 141 is coated on the substrate 131 with the pattern of the photoresist 136 in the form of a continuous microlens , comprising the plurality of nicrolenses.

[68] At this time, the coating of the metallic thin film 141 is typically chromium coating, and gold may be additionally coated thereon.

[69] After the coating of the metallic thin film 141 has been completed, the substrate 131 is placed on a plating apparatus and plated with nickel through an electroplating process, as shown in Fig. 11. At this time, a supplied electric current is a few amperes depending on each step. The plating thickness is 400 to 450nτn (on the basis of a 4-inch wafer), and a nickel-plated portion constitutes a stamper 142.

[70] When the stamper 142 has been made through the nickel electroplating, the stamper

142 is separated from the substrate 131. Here, the array pattern of the continuous nicrolens is transferred on the separated stamper 142 in a depressed fashion.

[71] That is, the stamper 142 (hereinafter, referred to as a "depressed stamper") has an array pattern of a continuous nicrolens feature formed in a depressed fashion, and the groove formed between spherical lens features is formed in a raised fashion.

[72] When the depressed stamper 142 with the continuous nicrolens feature in the depressed fashion is fabricated, the depressed stamper 142 can be used as a mold to form a light guiding plate or a nicrolens array with an array pattern of a continuous nicrolens in a raised fashion.

[73] In addition, the depressed stamper 142 may be used to form another raised stamper for use in fabricating a light guiding plate with an array pattern of a continuous nicrolens in a raised fashion.

[74] Fig. 12 is a schematic view showing a process of fabricating a raised stamper according to the embodiment of the present invention. As shown in this figure, nickel is newly electroplated on the array pattern of the continuous nicrolens in the depressed stamper 142.

[75] Through the plating process, a new nickel-plated portion 144 is formed. The nickel- plated portion 144 can be separated frαn the depressed stamper 142.

[76] The new nickel-plated portion 144 separated from the depressed stamper 142 constitutes a new raised stamper 144 on which the pattern in the depressed stamper 142 is transferred.

[77] That is, although the continuous nicrolens is formed in a raised fashion, a groove is formed in a depressed fashion between nicrolenses with uns>mnetrical curvatures.

[78] Thus, the raised stamper 144 can be used as a mold to form a light guiding plate

(not shown) with an array pattern of a continuous nicrolens in a depressed fashion.

[79] According to the present invention described above, in order to fabricate a three- dimensional continuous nicrolens, a plurality of cylindrical photoresists are formed such that they have the same diameter and the spacing between the photoresists in one direction is smaller than that in the other direction. Through heat treatment using reflow characteristics of the photoresists, each of the cylindrical photoresist is formed into a lens with a specific curvature depending on the height and diameter of the cylindrical photoresist. That is, the neighboring lenses are combined with each other in one direction, thereby enabling manufacture of a single continuous nicrolens with a plurality of curvatures.

[80] According to another embodiment of the present invention, a mask 221 to be used for a light-exposing process is first fabricated, as shown in Fig. 13. Here, as for the mask, a film mask or a chromium mask may be used depending on the precision of a pattern. In case of the use of a chrαnium mask, the mask can be fabricated with a precision of about 1 mm.

[81] Fig. 13 is a perspective view of a mask for use in the present invention. The mask

221 used for a light-exposing process comprises a first region 222 through which light can be transmitted, and a plurality of second regions 223 through which light cannot be transmitted. The second region 223 has a circular shape, but may be formed in other shapes such as a rectangle, pentagon, hexagon, or the like.

[82] Furthermore, the mask of the present invention may be formed such that the plurality of second regions 223 have the same shape, diameter and spacing. As shown in Fig. 13, however, it is preferred that the plurality of second regions 223 have the same shape but different diameters and spacing. The reason why the plurality of second regions 223 have the different diameters and spacing will be explained below.

[83] On the other hand, as illustrated in Fig. 14, a photoresist (PR) 232 is coated on a glass or silicone wafer substrate 231 using a spin coater. Here, the type of the PR 232 may vary according to the thickness thereof. In case of the use of a thick photoresist, for example, AZ-series 9260, the coated photoresist has a thickness of lOrrm. After the coating process has been completed, the coated substrate 231 is subjected to soft baking in an oven. At this time, the baking condition is preferably about 30 minutes at 95°C.

[84] After the soft baking has been completed, as shown in Fig. 15, the mask 221 is aligned on the PR-coated substrate 231 using an alignment key. A light-exposing process is performed for a predetermined period of time. At this time, the mask 221 to be used in the light-exposing process is a mask with the plurality of second regions 223 of different diameters and spacing. In Fig. 15, Rl, R2, R3 and R4 designate different diameters of the second regions 223, and Ll, L21, L3 and L4 designate different spacing between the second regions 223.

[85] After the light-exposing process has been completed, a developing process is carried out. The type of developing solution is AZ-series 400K. The developing condition is dipping for 6 minutes in the developing solution at 23°C. As the results of light-exposing process, as shown in Fig. 16, PR portions that have been exposed to the light through the mask 221 is melt down, and the remaining portions that have not been exposed to the light remain as they are. Consequently, only the portions of the PR 234 that have not been exposed to the light remain on the substrate 231. At this time, the portions of the PR 234 have cylindrical shapes since the second regions 223 have circular shapes.

[86] In addition, the cylindrical PRs 234 formed through the light-exposing process have different diameters and spacing according to the pattern of the second regions 223 in the mask 221. Here, the cylindrical PRs 234 have the same height.

[87] It can be seen from Fig. 17 that the cylindrical PRs 234 have different diameters and spacing. Fig. 17 is a sectional view of the light-exposed substrate taken in a longitudinal or transversal direction. Referring to Fig. 17, it can be seen that the PRs 234 have the same height but different diameters Wl, W2, and W3 and different spacing La and Lb.

[88] When the developing process has been completed, a reflow process is performed using a hot plate apparatus to allow the cylindrical PRs 234 of Figs. 16 and 17 to be curved. Here, in the reflow process, the PRs 234 are heated to be melted down. At this time, the reflow condition may vary with a shape to be manufactured, for example, preferably a few minutes at 100 to 200⁰C.

[89] Through the reflow process in the present invention, the cylindrical PRs 234 are formed into shapes shown in Figs. 18 and 19. Fig. 18 is a plan view showing the state of the PRs after the reflow process, and Fig. 19 is a sectional view showing the state of the PRs after the reflow process. That is, as shown in Figs. 18 and 19, the neighboring cylindrical PRs 234 are at least contacted or overlapped with each other through the reflow process to allow a nicro-curvature lens to be a rrulti-face lens or a multi- curvature lens, due to different inclinations Kl and K2 between the neighboring PRs. Consequently, when an inclination angle between neighboring PRs in the transversal direction and an inclination angle between neighboring PRs in the longitudinal direction are controlled, a portion of a nicrolens at a desired position can be manufactured into a milti-curvature lens. [90] The formation of the inclination angle, i.e., a groove, between the neighboring PRs is determined on the basis of the diameter of the second region 223 or the spacing between the neighboring second regions 223 in the mask 221 upon fabrication of the mask. If the neighboring PRs 234 do not have sufficiently large diameters as compared with the spacing between them or do not have sufficiently small spacing as compared with the diameters thereof, they fail to form a groove therebetween.

[91]

[92] *Accordingly, if the spacing between the neighboring PRs is fixed and the diameters of the PRs are gradually increased, an overlapping area between the neighboring PRs is increased after the reflow process. Alternatively, if the diameters of the neighboring PRs are fixed and the spacing between them is gradually decreased, the overlapping area between the neighboring PRs is increased after the reflow process. Here, if the overlapping area is decreased, the internal angle (i.e., inclination angle) of the formed groove becomes smaller. As the overlapping area is increased, the internal angle (inclination angle) of the groove becomes larger. Referring to Fig. 19, the inclination angle Kl in the case of a larger overlapping area is larger than the inclination angle K2.

[93] The inventor found these characteristics through experiments. The internal angle of the formed groove can be numericalized depending on the diameters of the PRs and the spacing between the PRs. A groove with a desired shape could be easily formed by controlling the second regions in the mask according to the inventor's intention. The formation of a groove with a desired shape means that curvature can be controlled in a desired direction on a curvature lens.

[94] When a multi-curvature lens is formed through the reflow process according to the shapes and spacing of neighboring PRs, as shown in Fig. 20, a metallic thin film 241 is coated on the substrate 231 on which the multi-curvature lens with a pattern of a plurality of microlenses has been formed. At this time, the coating of the metallic thin film 241 is typically chromium coating, and gold may be additionally coated thereon.

[95] When the coating of the metallic thin film has been completed, the substrate 231 is placed in a plating apparatus and plated with nickel through an electroplating process, as shown in Fig. 21. At this time, a supplied electric current is a few amperes depending on each step. The plating thickness is 400 to 450rrm (on the basis of a 4-inch wafer), and the nickel-plated portion constitutes a stamper 242.

[96] When the stamper 242 has been formed through the nickel electroplating, the stamper 242 is separated from the substrate 231. Here, the array pattern of the multi- curvature lens is transferred onto the stamper 242 in a depressed fashion. That is, the stamper 242 has the array pattern of the rrulti-curvature lens formed in a depressed fashion and grooves formed between spherical lenses in a raised fashion.

[97] When the stamper 242 with the pattern of the multi-curvature lens in the depressed fashion has been fabricated as described above, the stamper 242 is used as a mold to injectionHtnold a light guiding plate or a rrήcrolens array with a raised pattern of the multi-curvature lens.

[98] If a light guiding plate with an array pattern of a multi-curvature lens in a depressed fashion is desired to be manufactured, another nickel electroplating is newly performed on the stamper 242, and a new nickel-plated portion is separated from the stamper 242. The new nickel-plated portion separated from the stamper 242 constitutes a new stamper with features transferred frαn the stamper 242. That is, the new stamper has an array pattern of a multi-curvature lens in a raised fashion, and grooves formed in a depressed fashion between different curvature portions of the milti-curvature lens. Thus, the new stamper can be used as a mold to injectionmold a light guiding plate with an array pattern of a multi-curvature lens in a depressed pattern.

[99] Although the technical spirit of the present invention has been described with reference to the accompanying drawings, the description does not limit the present invention but merely explains the preferred embodiments of the present invention. Further, it will be understood by those skilled in the art that various changes and modifications can be made thereto without departing from the technical spirit and scope of the present invention.

Claims

[1] A method for manufacturing a continuous microlens on a light guiding plate using a semiconductor reflow process, the method comprising: a first step of aligning a mask on a substrate coated with a photoresist and performing a light-exposing process, the mask including a first region through which light can be transmitted and a plurality of second regions through which light cannot be transmitted; a second step of developing the light-exposed substrate to obtain a plurality of photoresists in the form of posts; a third step of performing a reflow process to allow the post-shaped photoresists to be curved until the post-shaped photoresists are combined with photoresists adjacent thereto in one direction to form a continuous microlens feature; a fourth step of fabricating a depressed stamper such that the photoresists defining the continuous microlens feature are engraved in a depressed fashion in the depressed stamper; and

* a fifth step of forming a light guiding plate by using the depressed stamper as a mold such that the continuous microlens is formed in the light guiding plate in a raised pattern.

[2] The method as claimed in claim 1, wherein the mask comprises a film mask or a chromium mask.

[3] The method as claimed in claim 1, wherein the second regions of the mask are arranged on an extension line in one direction such that neighboring second regions are close to each other and the arrangement of the second regions is spaced apart by a predetermined distance from another neighboring arrangement of second regions.

[4] The method as claimed in claim 1 , wherein each of the second regions of the mask is formed in a circular shape.

[5] The method as claimed in claim 1 , wherein the fourth step comprises the steps of: coating a metallic thin film on the substrate with a pattern of the continuous microlens feature; and electroplating the metallic thin film with nickel, and separating only a nickel- plated portion from the substrate to form the stamper.

[6] The method as claimed in claim 5, wherein the coating of the metallic thin film comprises chromium coating.

[7] The method as claimed in claim 6, wherein the coating of the metallic thin film further comprises additional coating of gold after the chromium coating.

[8] The method as claimed in claim 1, further comprising the steps of: fabricating a raised stamper using the depressed stamper as a master such that the continuous nicrolens feature of the depressed stamper is engraved in the raised stamper in a raised fashion; and forming a light guiding plate using the raised stamper as a mold such that the continuous nicrolens is formed in the light guiding plate in a depressed fashion.

[9] The method as claimed in claim 8, wherein the raised stamper is fabricated by performing nickel-plating on the array pattern of the continuous nicrolens of the depressed stamper, and separating a nickel-plated portion from the depressed stamper.

[10] A light guiding plate with a continuous nicrolens composed of a plurality of ni- crolenses, wherein the plurality of nicrolenses each of which has a hemispherical curvature are arranged on an extension line in one direction on the light guiding plate such that neighboring nicrolenses are overlapped with each other to form the continuous nicrolens, the continuous nicrolens is formed in plural on the light guiding plate, and the continuous nicrolenses are arranged such that neighboring continuous nicrolenses are spaced apart by an appropriate distance from each other.

[11] * The light guiding plate as claimed in claim 10, wherein a part of the plurality of continuous nicrolenses formed on the light guiding plate has a different size or is arranged in a different direction.

[12] A method for manufacturing a plurality of multi-curvature lenses using a semiconductor reflow process, the method comprising: a first step of aligning a first mask on a substrate coated with a photoresist and performing a light-exposing process, the first mask including a plurality of shield regions through which light cannot be transmitted, a part of the shield regions having a different diameter; a second step of developing the light-exposed substrate to obtain a plurality of photoresists in the form of posts; a third step of performing a reflow process to allow the post-shaped photoresists to be curved until at least a part of the post-shaped photoresists forms a multi- curvature lens feature in combination with neighboring photoresists; a fourth step of fabricating a first stamper in which the photoresists of which the at least part has the multi-curvature lens feature formed through the third step are engraved in a depressed fashion; and a fifth step of injectionHmolding a product using the first stamper as a mold such that a multi-curvature lens is formed in a depressed pattern in the product.

[13] The method as claimed in claim 12, wherein the first mask comprises a film mask or a chromium mask.

[14] The method as claimed in claim 12, wherein the plurality of shield regions of the first mask includes at least one shield region with a different area.

[15] The method as claimed in claim 12, wherein the plurality of shield regions of the first mask includes at least one shield region with different spacing with neighboring shield regions.

[16] The method as claimed in claim 14 or 15, wherein each of the shield regions of the first mask has a circular shape.

[17] The method as claimed in claim 16, wherein the fourth step comprises the steps of: coating a metallic thin film; electroplating the metallic thin film with nickel, and separating only a nickel- plated portion; and using the nickel-plated portion as the stamper.

[18] The method as claimed in claim 17, wherein the coating of the metallic thin film comprises chromium coating.

[19] The method as claimed in claim 18, wherein the coating of the metallic thin film further comprises additional coating of gold after the chromium coating.

[20] The method as claimed in claim 19, further comprising the steps of: fabricating a second stamper using the first stamper such that the rmlti-curvature lens feature is engraved in the second stamper in a raised fashion; and injection-molding a product using the second stamper as a mold such that the multi-curvature lens is formed in a depressed pattern in the product.

[21] A light guiding plate manufactured according to the method of claim 12, the light guiding plate comprising a plurality of curvature lenses in the form of ni- crolenses, wherein at least a part of the plurality of curvature lenses has different curvatures with respect to at least two different directions.